From fe3618525309939e06e457c44ad6d1230281d370 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrik=20Sch=C3=B6nfeldt?= <patrik@proxima.snft.de>
Date: Thu, 22 Aug 2024 09:27:03 +0200
Subject: [PATCH 01/10] Add planned change to changelog

---
 docs/whatsnew/v0-6-0.rst | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/docs/whatsnew/v0-6-0.rst b/docs/whatsnew/v0-6-0.rst
index 339fae4d9..122bbe7a7 100644
--- a/docs/whatsnew/v0-6-0.rst
+++ b/docs/whatsnew/v0-6-0.rst
@@ -10,6 +10,8 @@ API changes
   effectively the same) had double weight before. Also, if the
   initial storage level is defined, the costs just offset the
   objective value without changing anything else.
+* The parameters `GenericStorage.nominal_storage_capacity` and
+  `Flow.nominal_value` are now both called `nominal_calacity`.
 
 New features
 ############

From 6ed34e4b39e25e4c401e66d2496a15a66bea7995 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrik=20Sch=C3=B6nfeldt?= <patrik@proxima.snft.de>
Date: Thu, 22 Aug 2024 13:08:47 +0200
Subject: [PATCH 02/10] Rename Flow argument from nominal_value to
 nominal_capacity

I still have to keep explaining people what the nominal_value is
meant for and they just understand if I name it nominal_capacity,
instead. Reflecting a bit, the capacity of a Flow (e.g. a power line)
is easier to interpret as the "nominal value". Thus the refactoring.
---
 src/oemof/solph/flows/_flow.py      | 50 +++++++++++++++++++++--------
 tests/test_flows/test_flow_class.py |  4 +--
 tests/test_solph_network_classes.py |  6 ++--
 3 files changed, 42 insertions(+), 18 deletions(-)

diff --git a/src/oemof/solph/flows/_flow.py b/src/oemof/solph/flows/_flow.py
index 6ed8e97ab..ded156642 100644
--- a/src/oemof/solph/flows/_flow.py
+++ b/src/oemof/solph/flows/_flow.py
@@ -41,10 +41,10 @@ class Flow(Edge):
 
     Parameters
     ----------
-    nominal_value : numeric, :math:`P_{nom}` or
+    nominal_capacity : numeric, :math:`P_{nom}` or
             :class:`Investment <oemof.solph.options.Investment>`
-        The nominal value of the flow, either fixed or as an investement
-        optimisation. If this value is set the corresponding optimization
+        The nominal calacity of the flow, either fixed or as an investement
+        optimisation. If this value is set, the corresponding optimization
         variable of the flow object will be bounded by this value
         multiplied by min(lower bound)/max(upper bound).
     variable_costs : numeric (iterable or scalar), default: 0, :math:`c`
@@ -68,11 +68,11 @@ class Flow(Edge):
     full_load_time_max : numeric, :math:`t_{full\_load,max}`
         Maximum energy transported by the flow expressed as the time (in
         hours) that the flow would have to run at nominal capacity
-        (`nominal_value`).
+        (`nominal_capacity`).
     full_load_time_min : numeric, :math:`t_{full\_load,min}`
         Minimum energy transported by the flow expressed as the time (in
         hours) that the flow would have to run at nominal capacity
-        (`nominal_value`).
+        (`nominal_capacity`).
     integer : boolean
         Set True to bound the flow values to integers.
     nonconvex : :class:`NonConvex <oemof.solph.options.NonConvex>`
@@ -107,7 +107,7 @@ class Flow(Edge):
     --------
     Creating a fixed flow object:
 
-    >>> f = Flow(nominal_value=2, fix=[10, 4, 4], variable_costs=5)
+    >>> f = Flow(nominal_capacity=2, fix=[10, 4, 4], variable_costs=5)
     >>> f.variable_costs[2]
     5
     >>> f.fix[2]
@@ -115,14 +115,17 @@ class Flow(Edge):
 
     Creating a flow object with time-depended lower and upper bounds:
 
-    >>> f1 = Flow(min=[0.2, 0.3], max=0.99, nominal_value=100)
+    >>> f1 = Flow(min=[0.2, 0.3], max=0.99, nominal_capacity=100)
     >>> f1.max[1]
     0.99
     """  # noqa: E501
 
     def __init__(
         self,
+        nominal_capacity=None,
+        # --- BEGIN: To be removed for versions >= v0.7 ---
         nominal_value=None,
+        # --- END ---
         variable_costs=0,
         min=None,
         max=None,
@@ -176,6 +179,27 @@ def __init__(
             full_load_time_min = summed_min
         # --- END ---
 
+        # --- BEGIN: The following code can be removed for versions >= v0.7 ---
+        if nominal_value is not None:
+            msg = (
+                "For backward compatibility,"
+                " the option nominal_value overwrites the option"
+                " nominal_capacity."
+                + " Both options cannot be set at the same time."
+            )
+            if nominal_capacity is not None:
+                raise AttributeError(msg)
+            else:
+                warn(msg, FutureWarning)
+            nominal_capacity = nominal_value
+
+        msg = (
+            "\nThe parameter '{0}' is deprecated and will be removed "
+            + "in version v0.6.\nUse the parameter '{1}', "
+            + "to avoid this warning and future problems. "
+        )
+        # --- END ---
+
         super().__init__()
 
         if custom_attributes is not None:
@@ -189,12 +213,12 @@ def __init__(
             "{} must be a finite value. Passing an infinite "
             "value is not allowed."
         )
-        if isinstance(nominal_value, numbers.Real):
-            if not math.isfinite(nominal_value):
-                raise ValueError(infinite_error_msg.format("nominal_value"))
-            self.nominal_value = nominal_value
-        elif isinstance(nominal_value, Investment):
-            self.investment = nominal_value
+        if isinstance(nominal_capacity, numbers.Real):
+            if not math.isfinite(nominal_capacity):
+                raise ValueError(infinite_error_msg.format("nominal_capacity"))
+            self.nominal_value = nominal_capacity
+        elif isinstance(nominal_capacity, Investment):
+            self.investment = nominal_capacity
 
         if fixed_costs is not None:
             msg = (
diff --git a/tests/test_flows/test_flow_class.py b/tests/test_flows/test_flow_class.py
index f59c907b6..4ddcda1fb 100644
--- a/tests/test_flows/test_flow_class.py
+++ b/tests/test_flows/test_flow_class.py
@@ -21,7 +21,7 @@ def test_summed_max_future_warning():
     """Can be removed with v0.6."""
     msg = "The parameter 'summed_max' is deprecated and will be removed"
     with warnings.catch_warnings(record=True) as w:
-        Flow(nominal_value=1, summed_max=2)
+        Flow(nominal_capacity=1, summed_max=2)
         assert len(w) == 1
         assert msg in str(w[-1].message)
 
@@ -30,7 +30,7 @@ def test_summed_min_future_warning():
     """Can be removed with v0.6."""
     msg = "The parameter 'summed_min' is deprecated and will be removed"
     with warnings.catch_warnings(record=True) as w:
-        Flow(nominal_value=1, summed_min=2)
+        Flow(nominal_capacity=1, summed_min=2)
         assert len(w) == 1
         assert msg in str(w[-1].message)
 
diff --git a/tests/test_solph_network_classes.py b/tests/test_solph_network_classes.py
index 71726a286..5edad18c9 100644
--- a/tests/test_solph_network_classes.py
+++ b/tests/test_solph_network_classes.py
@@ -128,12 +128,12 @@ def test_flow_with_fix_and_min_max():
 
 
 def test_infinite_values():
-    msg1 = "nominal_value must be a finite value"
+    msg1 = "nominal_capacity must be a finite value"
     msg2 = "max must be a finite value"
     with pytest.raises(ValueError, match=msg1):
-        solph.flows.Flow(nominal_value=float("+inf"))
+        solph.flows.Flow(nominal_capacity=float("+inf"))
     with pytest.raises(ValueError, match=msg2):
-        solph.flows.Flow(nominal_value=1, max=float("+inf"))
+        solph.flows.Flow(nominal_capacity=1, max=float("+inf"))
 
 
 def test_attributes_needing_nominal_value_get_it():

From e91c7fc97e46a66858b8c3116d26d60d5171b0fd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrik=20Sch=C3=B6nfeldt?= <patrik@proxima.snft.de>
Date: Thu, 22 Aug 2024 13:21:27 +0200
Subject: [PATCH 03/10] Test Flow(nominal_value) wrapper

---
 tests/test_flows/test_simple_flow.py | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tests/test_flows/test_simple_flow.py b/tests/test_flows/test_simple_flow.py
index 3c351e0ce..8dca29043 100644
--- a/tests/test_flows/test_simple_flow.py
+++ b/tests/test_flows/test_simple_flow.py
@@ -55,3 +55,17 @@ def test_full_load_time_min():
     flow_result = list(_run_flow_model(flow)["flow"][:-1])
 
     assert flow_result == pytest.approx(4 * [2] + [1] + 5 * [0])
+
+
+# --- BEGIN: The following code can be removed for versions >= v0.7 ---
+def test_nominal_value_warning():
+    with pytest.warns(FutureWarning, match="nominal_value"):
+        _ = solph.flows.Flow(nominal_value=2)
+
+
+def test_nominal_value_error():
+    with pytest.raises(AttributeError, match="nominal_value"):
+        _ = solph.flows.Flow(nominal_value=2, nominal_capacity=1)
+
+
+# --- END ---

From 375cf7c7d8180373a1da21ca4aee868741aa8d35 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrik=20Sch=C3=B6nfeldt?= <patrik@proxima.snft.de>
Date: Thu, 22 Aug 2024 13:57:32 +0200
Subject: [PATCH 04/10] Rename Flow argument nominal_value to nominal_capacity

---
 docs/usage.rst                                | 70 +++++++++----------
 docs/whatsnew/v0-2-2.rst                      |  2 +-
 docs/whatsnew/v0-5-1.rst                      |  2 +-
 docs/whatsnew/v0-5-3.rst                      |  2 +-
 docs/whatsnew/v0-6-0.rst                      |  2 +-
 examples/activity_costs/activity_costs.py     |  6 +-
 examples/basic_example/basic_example.py       | 18 ++---
 .../dual_variable_example.py                  | 12 ++--
 examples/electrical/transshipment.py          | 14 ++--
 .../emission_constraint.py                    |  8 ++-
 examples/excel_reader/dispatch.py             | 12 ++--
 .../flexible_modelling/add_constraints.py     |  6 +-
 .../flexible_modelling/saturating_storage.py  |  6 +-
 examples/flow_count_limit/flow_count_limit.py |  8 +--
 .../example_generic_invest.py                 |  8 +--
 examples/gradient_example/gradient_example.py |  4 +-
 .../diesel_genset_nonconvex_investment.py     | 12 ++--
 .../house_with_nonconvex_investment.py        |  8 +--
 .../house_without_nonconvex_investment.py     | 10 +--
 .../minimal_invest.py                         |  4 +-
 examples/min_max_runtimes/min_max_runtimes.py |  6 +-
 ...fset_diesel_genset_nonconvex_investment.py | 12 ++--
 examples/simple_dispatch/simple_dispatch.py   | 23 +++---
 .../startup_shutdown.py                       |  6 +-
 .../storage_balanced_unbalanced/storage.py    |  6 +-
 examples/storage_costs/storage_costs.py       |  8 +--
 .../v1_invest_optimize_all_technologies.py    |  9 +--
 ...v2_invest_optimize_only_gas_and_storage.py |  8 +--
 ...optimize_only_storage_with_fossil_share.py | 10 +--
 ...mize_all_technologies_with_fossil_share.py | 11 +--
 .../storage_level_constraint.py               | 10 +--
 .../non_equidistant_time_step_example.py      |  6 +-
 .../simple_time_step_example.py               |  6 +-
 examples/tuple_as_labels/tuple_as_label.py    | 20 ++++--
 examples/variable_chp/variable_chp.py         | 16 +++--
 src/oemof/solph/_console_scripts.py           |  4 +-
 .../components/_extraction_turbine_chp.py     |  2 +-
 .../solph/components/_generic_storage.py      |  4 +-
 src/oemof/solph/components/_link.py           |  4 +-
 .../solph/components/_offset_converter.py     |  2 +-
 .../_piecewise_linear_converter.py            |  2 +-
 .../solph/constraints/equate_variables.py     |  4 +-
 src/oemof/solph/constraints/integral_limit.py |  4 +-
 .../solph/constraints/investment_limit.py     |  6 +-
 .../flows/experimental/_electrical_line.py    |  2 +-
 tests/test_components.py                      | 10 +--
 .../test_components/test_offset_converter.py  | 24 ++++---
 tests/test_components/test_sink.py            |  2 +-
 tests/test_components/test_source.py          |  2 +-
 tests/test_components/test_storage.py         | 32 +++++----
 .../test_constraints_module.py                |  8 +--
 tests/test_constraints/test_equate_flows.py   |  8 +--
 .../test_constraints/test_flow_count_limit.py |  8 +--
 tests/test_constraints/test_storage_level.py  | 18 +++--
 tests/test_flows/test_flow_class.py           |  4 +-
 tests/test_flows/test_non_convex_flow.py      | 18 ++---
 tests/test_flows/test_simple_flow.py          |  6 +-
 tests/test_grouping.py                        |  6 +-
 tests/test_models.py                          | 12 ++--
 tests/test_non_equidistant_time_index.py      |  4 +-
 tests/test_options.py                         |  2 +-
 tests/test_outputlib/__init__.py              | 22 +++---
 tests/test_processing.py                      |  4 +-
 .../test_connect_invest.py                    |  8 +--
 .../test_add_constraints.py                   |  6 +-
 .../test_generic_chp/test_generic_chp.py      |  4 +-
 .../test_simple_invest_fixed.py               |  6 +-
 .../test_solph/test_lopf/test_lopf.py         | 12 ++--
 .../test_multi_period_dispatch_model.py       | 42 ++++++-----
 .../test_multi_period_investment_model.py     | 38 +++++-----
 .../test_piecewiselineartransformer.py        |  6 +-
 .../test_simple_model/test_simple_dispatch.py | 23 +++---
 .../test_simple_dispatch_one.py               | 12 ++--
 ...t_simple_dispatch_one_explicit_timemode.py | 12 ++--
 .../test_simple_model/test_simple_invest.py   | 22 +++---
 .../test_invest_storage_regression.py         |  8 +--
 .../test_storage_investment.py                | 15 ++--
 .../test_storage_with_tuple_label.py          | 17 +++--
 .../test_variable_chp/test_variable_chp.py    | 16 +++--
 tests/test_solph_network_classes.py           |  2 +-
 tests/test_warnings.py                        |  6 +-
 81 files changed, 470 insertions(+), 380 deletions(-)

diff --git a/docs/usage.rst b/docs/usage.rst
index 58247d9d9..a51fb2d66 100644
--- a/docs/usage.rst
+++ b/docs/usage.rst
@@ -266,13 +266,13 @@ Sink (basic)
 A sink is normally used to define the demand within an energy model but it can also be used to detect excesses.
 
 The example shows the electricity demand of the electricity_bus defined above.
-The *'my_demand_series'* should be sequence of normalised valueswhile the *'nominal_value'* is the maximum demand the normalised sequence is multiplied with.
+The *'my_demand_series'* should be sequence of normalised valueswhile the *'nominal_capacity'* is the maximum demand the normalised sequence is multiplied with.
 Giving *'my_demand_series'* as parameter *'fix'* means that the demand cannot be changed by the solver.
 
 .. code-block:: python
 
     solph.components.Sink(label='electricity_demand', inputs={electricity_bus: solph.flows.Flow(
-        fix=my_demand_series, nominal_value=nominal_demand)})
+        fix=my_demand_series, nominal_capacity=nominal_demand)})
 
 In contrast to the demand sink the excess sink has normally less restrictions but is open to take the whole excess.
 
@@ -290,21 +290,21 @@ Source (basic)
 
 A source can represent a pv-system, a wind power plant, an import of natural gas or a slack variable to avoid creating an in-feasible model.
 
-While a wind power plant will have as feed-in depending on the weather conditions the natural_gas import might be restricted by maximum value (*nominal_value*) and an annual limit (*full_load_time_max*).
+While a wind power plant will have as feed-in depending on the weather conditions the natural_gas import might be restricted by maximum value (*nominal_capacity*) and an annual limit (*full_load_time_max*).
 As we do have to pay for imported gas we should set variable costs.
 Comparable to the demand series an *fix* is used to define a fixed the normalised output of a wind power plant.
 Alternatively, you might use *max* to allow for easy curtailment.
-The *nominal_value* sets the installed capacity.
+The *nominal_capacity* sets the installed capacity.
 
 .. code-block:: python
 
     solph.components.Source(
         label='import_natural_gas',
         outputs={my_energysystem.groups['natural_gas']: solph.flows.Flow(
-            nominal_value=1000, full_load_time_max=1000000, variable_costs=50)})
+            nominal_capacity=1000, full_load_time_max=1000000, variable_costs=50)})
 
     solph.components.Source(label='wind', outputs={electricity_bus: solph.flows.Flow(
-        fix=wind_power_feedin_series, nominal_value=1000000)})
+        fix=wind_power_feedin_series, nominal_capacity=1000000)})
 
 .. note:: The Source class is only a plug and provides no additional constraints or variables.
 
@@ -327,7 +327,7 @@ A condensing power plant can be defined by a converter with one input (fuel) and
     solph.components.Converter(
         label="pp_gas",
         inputs={bgas: solph.flows.Flow()},
-        outputs={b_el: solph.flows.Flow(nominal_value=10e10)},
+        outputs={b_el: solph.flows.Flow(nominal_capacity=10e10)},
         conversion_factors={electricity_bus: 0.58})
 
 A CHP power plant would be defined in the same manner but with two outputs:
@@ -341,8 +341,8 @@ A CHP power plant would be defined in the same manner but with two outputs:
     solph.components.Converter(
         label='pp_chp',
         inputs={b_gas: Flow()},
-        outputs={b_el: Flow(nominal_value=30),
-                 b_th: Flow(nominal_value=40)},
+        outputs={b_el: Flow(nominal_capacity=30),
+                 b_th: Flow(nominal_capacity=40)},
         conversion_factors={b_el: 0.3, b_th: 0.4})
 
 A CHP power plant with 70% coal and 30% natural gas can be defined with two inputs and two outputs:
@@ -357,8 +357,8 @@ A CHP power plant with 70% coal and 30% natural gas can be defined with two inpu
     solph.components.Converter(
         label='pp_chp',
         inputs={b_gas: Flow(), b_coal: Flow()},
-        outputs={b_el: Flow(nominal_value=30),
-                 b_th: Flow(nominal_value=40)},
+        outputs={b_el: Flow(nominal_capacity=30),
+                 b_th: Flow(nominal_capacity=40)},
         conversion_factors={b_el: 0.3, b_th: 0.4,
                             b_coal: 0.7, b_gas: 0.3})
 
@@ -428,7 +428,7 @@ applies when the second flow is zero (*`conversion_factor_full_condensation`*).
 
     solph.components._extractionTurbineCHP(
         label='variable_chp_gas',
-        inputs={b_gas: solph.flows.Flow(nominal_value=10e10)},
+        inputs={b_gas: solph.flows.Flow(nominal_capacity=10e10)},
         outputs={b_el: solph.flows.Flow(), b_th: solph.flows.Flow()},
         conversion_factors={b_el: 0.3, b_th: 0.5},
         conversion_factor_full_condensation={b_el: 0.5})
@@ -559,15 +559,15 @@ GenericStorage (component)
 A component to model a storage with its basic characteristics. The
 GenericStorage is designed for one input and one output.
 The ``nominal_storage_capacity`` of the storage signifies the storage capacity. You can either set it to the net capacity or to the gross capacity and limit it using the min/max attribute.
-To limit the input and output flows, you can define the ``nominal_value`` in the Flow objects.
+To limit the input and output flows, you can define the ``nominal_capacity`` in the Flow objects.
 Furthermore, an efficiency for loading, unloading and a loss rate can be defined.
 
 .. code-block:: python
 
     solph.components.GenericStorage(
         label='storage',
-        inputs={b_el: solph.flows.Flow(nominal_value=9, variable_costs=10)},
-        outputs={b_el: solph.flows.Flow(nominal_value=25, variable_costs=10)},
+        inputs={b_el: solph.flows.Flow(nominal_capacity=9, variable_costs=10)},
+        outputs={b_el: solph.flows.Flow(nominal_capacity=25, variable_costs=10)},
         loss_rate=0.001, nominal_storage_capacity=50,
         inflow_conversion_factor=0.98, outflow_conversion_factor=0.8)
 
@@ -588,8 +588,8 @@ The following code block shows an example of the storage parametrization for the
 
     solph.components.GenericStorage(
         label='storage',
-        inputs={b_el: solph.flows.Flow(nominal_value=9, variable_costs=10)},
-        outputs={b_el: solph.flows.Flow(nominal_value=25, variable_costs=10)},
+        inputs={b_el: solph.flows.Flow(nominal_capacity=9, variable_costs=10)},
+        outputs={b_el: solph.flows.Flow(nominal_capacity=25, variable_costs=10)},
         loss_rate=0.001, nominal_storage_capacity=50,
         initial_storage_level=0.5, balanced=True,
         inflow_conversion_factor=0.98, outflow_conversion_factor=0.8)
@@ -625,7 +625,7 @@ Based on the `GenericStorage` object the `GenericInvestmentStorageBlock` adds tw
     *	Invest into the flow parameters e.g. a turbine or a pump
     *	Invest into capacity of the storage  e.g. a basin or a battery cell
 
-Investment in this context refers to the value of the variable for the 'nominal_value' (installed capacity) in the investment mode.
+Investment in this context refers to the value of the variable for the 'nominal_capacity' (installed capacity) in the investment mode.
 
 As an addition to other flow-investments, the storage class implements the possibility to couple or decouple the flows
 with the capacity of the storage.
@@ -643,8 +643,8 @@ The following example pictures a Pumped Hydroelectric Energy Storage (PHES). Bot
 
     solph.components.GenericStorage(
         label='PHES',
-        inputs={b_el: solph.flows.Flow(nominal_value=solph.Investment(ep_costs=500))},
-        outputs={b_el: solph.flows.Flow(nominal_value=solph.Investment(ep_costs=500)},
+        inputs={b_el: solph.flows.Flow(nominal_capacity=solph.Investment(ep_costs=500))},
+        outputs={b_el: solph.flows.Flow(nominal_capacity=solph.Investment(ep_costs=500)},
         loss_rate=0.001,
         inflow_conversion_factor=0.98, outflow_conversion_factor=0.8),
         investment = solph.Investment(ep_costs=40))
@@ -755,7 +755,7 @@ Then we can create our component with the buses attached to it.
     ...     label='boiler',
     ...     inputs={
     ...         bfuel: solph.flows.Flow(
-    ...             nominal_value=P_out_max,
+    ...             nominal_capacity=P_out_max,
     ...             max=l_max,
     ...             min=l_min,
     ...             nonconvex=solph.NonConvex()
@@ -775,7 +775,7 @@ Then we can create our component with the buses attached to it.
     will serve as the reference for the `conversion_factors` and the
     `normed_offsets`. The `NonConvex` flow also holds
 
-    - the `nominal_value` (or `Investment` in case of investment optimization),
+    - the `nominal_capacity` (can be `Investment` in case of investment optimization),
     - the `min` and
     - the `max` attributes.
 
@@ -897,7 +897,7 @@ This small example of PV, grid and SinkDSM shows how to use the component
     grid = solph.components.Source(label='Grid',
                         outputs={
                             b_elec: solph.flows.Flow(
-                                nominal_value=10000,
+                                nominal_capacity=10000,
                                 variable_costs=50)}
                         )
     es.add(grid)
@@ -907,7 +907,7 @@ This small example of PV, grid and SinkDSM shows how to use the component
                           outputs={
                               b_elec: solph.flows.Flow(
                                   fix=data['pv'],
-                                  nominal_value=3.5)}
+                                  nominal_capacity=3.5)}
                           )
     es.add(s_wind)
 
@@ -956,7 +956,7 @@ The annual savings by building up new capacity must therefore compensate the ann
 See the API of the :py:class:`~oemof.solph.options.Investment` class to see all possible parameters.
 
 Basically, an instance of the Investment class can be added to a Flow, a
-Storage or a DSM Sink. All parameters that usually refer to the *nominal_value/capacity* will
+Storage or a DSM Sink. All parameters that usually refer to the *nominal_capacity* will
 now refer to the investment variables and existing capacity. It is also
 possible to set a maximum limit for the capacity that can be build.
 If existing capacity is considered for a component with investment mode enabled,
@@ -981,7 +981,7 @@ turbines.
 
     solph.components.Source(label='new_wind_pp', outputs={electricity: solph.flows.Flow(
         fix=wind_power_time_series,
-	nominal_value=solph.Investment(ep_costs=epc, maximum=50000))})
+	nominal_capacity=solph.Investment(ep_costs=epc, maximum=50000))})
 
 Let's slightly alter the case and consider for already existing wind power
 capacity of 20,000 kW. We're still expecting the total wind power capacity, thus we
@@ -991,7 +991,7 @@ allow for 30,000 kW of new installations and formulate as follows.
 
     solph.components.Source(label='new_wind_pp', outputs={electricity: solph.flows.Flow(
         fix=wind_power_time_series,
-	    nominal_value=solph.Investment(ep_costs=epc,
+	    nominal_capacity=solph.Investment(ep_costs=epc,
 	                                maximum=30000,
 	                                existing=20000))})
 
@@ -1026,7 +1026,7 @@ example of a converter:
         label='converter_nonconvex',
         inputs={bus_0: solph.flows.Flow()},
         outputs={bus_1: solph.flows.Flow(
-            nominal_value=solph.Investment(
+            nominal_capacity=solph.Investment(
                 ep_costs=4,
                 maximum=100,
                 minimum=20,
@@ -1183,7 +1183,7 @@ Then you add all the *components* and *buses* to your energy system, just as you
         label="electricity_demand",
         inputs={
             electricity_bus: solph.flows.Flow(
-                nominal_value=1000, fix=[0.8] * len(my_index)
+                nominal_capacity=1000, fix=[0.8] * len(my_index)
             )
         },
     )
@@ -1212,7 +1212,7 @@ Here is an example
         inputs={hydrogen_bus: solph.flows.Flow()},
         outputs={
             electricity_bus: solph.flows.Flow(
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     maximum=1000,
                     ep_costs=1e6,
                     lifetime=30,
@@ -1246,7 +1246,7 @@ This would mean that for investments in the particular period, these values woul
         inputs={hydrogen_bus: solph.flows.Flow()},
         outputs={
             electricity_bus: solph.flows.Flow(
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     maximum=1000,
                     ep_costs=[1e6, 1.1e6],
                     lifetime=30,
@@ -1273,7 +1273,7 @@ For components that is not invested into, you also can specify some additional a
         inputs={coal_bus: solph.flows.Flow()},
         outputs={
             electricity_bus: solph.flows.Flow(
-                nominal_value=600,
+                nominal_capacity=600,
                 max=1,
                 min=0.4,
                 lifetime=50,
@@ -1377,9 +1377,9 @@ class, and only the optimal dispatch strategy of an existing asset with a given
         inputs={b_gas: solph.flows.Flow()},
         outputs={b_el: solph.flows.Flow(
             nonconvex=solph.NonConvex(),
-            nominal_value=30,
+            nominal_capacity=30,
             min=0.5),
-        b_th: solph.flows.Flow(nominal_value=40)},
+        b_th: solph.flows.Flow(nominal_capacity=40)},
         conversion_factors={b_el: 0.3, b_th: 0.4})
 
 The class :py:class:`~oemof.solph.options.NonConvex` for the electrical output of the created Converter (i.e., CHP)
@@ -1421,7 +1421,7 @@ This nonlinearity is linearised in the
                 min=0.2,
                 max=1,
                 nonconvex=solph.NonConvex(),
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     ep_costs=90,
                     maximum=150, # required for the linearization
                 ),
diff --git a/docs/whatsnew/v0-2-2.rst b/docs/whatsnew/v0-2-2.rst
index 2af434373..d2c191e6d 100644
--- a/docs/whatsnew/v0-2-2.rst
+++ b/docs/whatsnew/v0-2-2.rst
@@ -29,7 +29,7 @@ New features
   `invest_relation_output_capacity` replace the existing attributes
   `nominal_input_capacity_ratio` and `nominal_input_capacity_ratio` for the
   investment mode. In case of the dispatch mode one should use the
-  `nominal_value` of the Flow classes. The attributes
+  `nominal_capacity` of the Flow classes. The attributes
   `nominal_input_capacity_ratio` and `nominal_input_capacity_ratio` will be
   removed in v0.3.0. Please adapt your application to avoid problems in the
   future (`Issue #480 <https://github.com/oemof/oemof-solph/pull/480>`_).
diff --git a/docs/whatsnew/v0-5-1.rst b/docs/whatsnew/v0-5-1.rst
index 06c327774..9a2b30ad9 100644
--- a/docs/whatsnew/v0-5-1.rst
+++ b/docs/whatsnew/v0-5-1.rst
@@ -13,7 +13,7 @@ API changes
   (Note that we always had the argument "conversion_factor".)
 * Unify API for constant sized objects and sizing of investment. For both, `Flow` and
   `GenericStorage`, the argument `investment` is now deprecated. Instead,
-  `nominal_value` and `nominal_storage_capacity` accept an `Investment` object.
+  `nominal_capacity` and `nominal_storage_capacity` accept an `Investment` object.
 * Change investment for experimental :class:`oemof.solph.components.experimental._sink_dsm.SinkDSM`: Remove
   obsolete parameters `flex_share_down` and `flex_share_up`.
 * Mainline link component :class:`oemof.solph.components._link.Link` from experimental.
diff --git a/docs/whatsnew/v0-5-3.rst b/docs/whatsnew/v0-5-3.rst
index c4dcb591f..6aa70ff6a 100644
--- a/docs/whatsnew/v0-5-3.rst
+++ b/docs/whatsnew/v0-5-3.rst
@@ -9,7 +9,7 @@ API changes
   to the `NonConvex` flow, and `normed_offsets` with the normed offsets
   relative to the `NonConvex` flow.
 * The `NonConvex` attribute must be specified for one of `Flow` at the inlets
-  or outlets of the `OffsetConverter`. `min`, `max` and `nominal_value` have to
+  or outlets of the `OffsetConverter`. `min`, `max` and `nominal_capacity` have to
   be specified for the same `Flow`.
 
 New features
diff --git a/docs/whatsnew/v0-6-0.rst b/docs/whatsnew/v0-6-0.rst
index 122bbe7a7..5b95cd94b 100644
--- a/docs/whatsnew/v0-6-0.rst
+++ b/docs/whatsnew/v0-6-0.rst
@@ -11,7 +11,7 @@ API changes
   initial storage level is defined, the costs just offset the
   objective value without changing anything else.
 * The parameters `GenericStorage.nominal_storage_capacity` and
-  `Flow.nominal_value` are now both called `nominal_calacity`.
+  `Flow.nominal_capacity` are now both called `nominal_calacity`.
 
 New features
 ############
diff --git a/examples/activity_costs/activity_costs.py b/examples/activity_costs/activity_costs.py
index 9f129c015..2ecb4b2e4 100644
--- a/examples/activity_costs/activity_costs.py
+++ b/examples/activity_costs/activity_costs.py
@@ -69,14 +69,14 @@ def main():
 
     sink_heat = solph.components.Sink(
         label="demand",
-        inputs={b_heat: solph.Flow(fix=demand_heat, nominal_value=1)},
+        inputs={b_heat: solph.Flow(fix=demand_heat, nominal_capacity=1)},
     )
 
     fireplace = solph.components.Source(
         label="fireplace",
         outputs={
             b_heat: solph.Flow(
-                nominal_value=3,
+                nominal_capacity=3,
                 variable_costs=0,
                 nonconvex=solph.NonConvex(activity_costs=activity_costs),
             )
@@ -85,7 +85,7 @@ def main():
 
     boiler = solph.components.Source(
         label="boiler",
-        outputs={b_heat: solph.Flow(nominal_value=10, variable_costs=1)},
+        outputs={b_heat: solph.Flow(nominal_capacity=10, variable_costs=1)},
     )
 
     es.add(sink_heat, fireplace, boiler)
diff --git a/examples/basic_example/basic_example.py b/examples/basic_example/basic_example.py
index b188b4ca8..cfd8e32f5 100644
--- a/examples/basic_example/basic_example.py
+++ b/examples/basic_example/basic_example.py
@@ -173,7 +173,7 @@ def main(dump_and_restore=False):
             label="wind",
             outputs={
                 bus_electricity: flows.Flow(
-                    fix=data["wind"], nominal_value=1000000
+                    fix=data["wind"], nominal_capacity=1000000
                 )
             },
         )
@@ -185,20 +185,20 @@ def main(dump_and_restore=False):
             label="pv",
             outputs={
                 bus_electricity: flows.Flow(
-                    fix=data["pv"], nominal_value=582000
+                    fix=data["pv"], nominal_capacity=582000
                 )
             },
         )
     )
 
     # create simple sink object representing the electrical demand
-    # nominal_value is set to 1 because demand_el is not a normalised series
+    # nominal_capacity is set to 1 because demand_el is not a normalised series
     energysystem.add(
         components.Sink(
             label="demand",
             inputs={
                 bus_electricity: flows.Flow(
-                    fix=data["demand_el"], nominal_value=1
+                    fix=data["demand_el"], nominal_capacity=1
                 )
             },
         )
@@ -211,7 +211,7 @@ def main(dump_and_restore=False):
             inputs={bus_gas: flows.Flow()},
             outputs={
                 bus_electricity: flows.Flow(
-                    nominal_value=10e10, variable_costs=50
+                    nominal_capacity=10e10, variable_costs=50
                 )
             },
             conversion_factors={bus_electricity: 0.58},
@@ -220,15 +220,17 @@ def main(dump_and_restore=False):
 
     # create storage object representing a battery
     nominal_capacity = 10077997
-    nominal_value = nominal_capacity / 6
+    nominal_capacity = nominal_capacity / 6
 
     battery_storage = components.GenericStorage(
         nominal_storage_capacity=nominal_capacity,
         label=STORAGE_LABEL,
-        inputs={bus_electricity: flows.Flow(nominal_value=nominal_value)},
+        inputs={
+            bus_electricity: flows.Flow(nominal_capacity=nominal_capacity)
+        },
         outputs={
             bus_electricity: flows.Flow(
-                nominal_value=nominal_value, variable_costs=0.001
+                nominal_capacity=nominal_capacity, variable_costs=0.001
             )
         },
         loss_rate=0.00,
diff --git a/examples/dual_variable_example/dual_variable_example.py b/examples/dual_variable_example/dual_variable_example.py
index 4ccc1105a..0e26c2472 100644
--- a/examples/dual_variable_example/dual_variable_example.py
+++ b/examples/dual_variable_example/dual_variable_example.py
@@ -198,7 +198,7 @@ def main():
     energysystem.add(
         cmp.Source(
             label="pv",
-            outputs={bus_elec: flows.Flow(fix=pv, nominal_value=700)},
+            outputs={bus_elec: flows.Flow(fix=pv, nominal_capacity=700)},
         )
     )
 
@@ -206,7 +206,7 @@ def main():
     energysystem.add(
         cmp.Sink(
             label="demand",
-            inputs={bus_elec: flows.Flow(fix=demand, nominal_value=1)},
+            inputs={bus_elec: flows.Flow(fix=demand, nominal_capacity=1)},
         )
     )
 
@@ -215,7 +215,7 @@ def main():
         cmp.Converter(
             label="pp_gas",
             inputs={bus_gas: flows.Flow()},
-            outputs={bus_elec: flows.Flow(nominal_value=400)},
+            outputs={bus_elec: flows.Flow(nominal_capacity=400)},
             conversion_factors={bus_elec: 0.5},
         )
     )
@@ -225,9 +225,11 @@ def main():
     storage = cmp.GenericStorage(
         nominal_storage_capacity=cap,
         label="storage",
-        inputs={bus_elec: flows.Flow(nominal_value=cap / 6)},
+        inputs={bus_elec: flows.Flow(nominal_capacity=cap / 6)},
         outputs={
-            bus_elec: flows.Flow(nominal_value=cap / 6, variable_costs=0.001)
+            bus_elec: flows.Flow(
+                nominal_capacity=cap / 6, variable_costs=0.001
+            )
         },
         loss_rate=0.00,
         initial_storage_level=0,
diff --git a/examples/electrical/transshipment.py b/examples/electrical/transshipment.py
index d5e0e53ef..3a1e181e4 100644
--- a/examples/electrical/transshipment.py
+++ b/examples/electrical/transshipment.py
@@ -144,8 +144,8 @@ def main():
             label="line_0",
             inputs={b_0: Flow(), b_1: Flow()},
             outputs={
-                b_1: Flow(nominal_value=Investment()),
-                b_0: Flow(nominal_value=Investment()),
+                b_1: Flow(nominal_capacity=Investment()),
+                b_0: Flow(nominal_capacity=Investment()),
             },
             conversion_factors={(b_0, b_1): 0.95, (b_1, b_0): 0.9},
         )
@@ -154,26 +154,28 @@ def main():
     es.add(
         cmp.Source(
             label="gen_0",
-            outputs={b_0: Flow(nominal_value=100, variable_costs=50)},
+            outputs={b_0: Flow(nominal_capacity=100, variable_costs=50)},
         )
     )
 
     es.add(
         cmp.Source(
             label="gen_1",
-            outputs={b_1: Flow(nominal_value=100, variable_costs=50)},
+            outputs={b_1: Flow(nominal_capacity=100, variable_costs=50)},
         )
     )
 
     es.add(
         cmp.Sink(
-            label="load_0", inputs={b_0: Flow(nominal_value=150, fix=[0, 1])}
+            label="load_0",
+            inputs={b_0: Flow(nominal_capacity=150, fix=[0, 1])},
         )
     )
 
     es.add(
         cmp.Sink(
-            label="load_1", inputs={b_1: Flow(nominal_value=150, fix=[1, 0])}
+            label="load_1",
+            inputs={b_1: Flow(nominal_capacity=150, fix=[1, 0])},
         )
     )
 
diff --git a/examples/emission_constraint/emission_constraint.py b/examples/emission_constraint/emission_constraint.py
index 73537ead4..bced70d38 100644
--- a/examples/emission_constraint/emission_constraint.py
+++ b/examples/emission_constraint/emission_constraint.py
@@ -57,7 +57,7 @@ def main():
             label="biomass",
             outputs={
                 bel: solph.Flow(
-                    nominal_value=100,
+                    nominal_capacity=100,
                     variable_costs=10,
                     fix=[0.1, 0.2, 0.3],
                     custom_attributes={"emission_factor": 0.01},
@@ -84,7 +84,9 @@ def main():
             label="demand",
             inputs={
                 bel: solph.Flow(
-                    nominal_value=200, variable_costs=10, fix=[0.1, 0.2, 0.3]
+                    nominal_capacity=200,
+                    variable_costs=10,
+                    fix=[0.1, 0.2, 0.3],
                 )
             },
         )
@@ -95,7 +97,7 @@ def main():
         solph.components.Converter(
             label="pp_gas",
             inputs={bgas: solph.Flow()},
-            outputs={bel: solph.Flow(nominal_value=200)},
+            outputs={bel: solph.Flow(nominal_capacity=200)},
             conversion_factors={bel: 0.58},
         )
     )
diff --git a/examples/excel_reader/dispatch.py b/examples/excel_reader/dispatch.py
index 97baad936..efb534f24 100644
--- a/examples/excel_reader/dispatch.py
+++ b/examples/excel_reader/dispatch.py
@@ -178,7 +178,7 @@ def create_nodes(nd=None):
     for i, re in nd["renewables"].iterrows():
         if re["active"]:
             # set static outflow values
-            outflow_args = {"nominal_value": re["capacity"]}
+            outflow_args = {"nominal_capacity": re["capacity"]}
             # get time series for node and parameter
             for col in nd["timeseries"].columns.values:
                 if col.split(".")[0] == re["label"]:
@@ -196,7 +196,7 @@ def create_nodes(nd=None):
     for i, de in nd["demand"].iterrows():
         if de["active"]:
             # set static inflow values
-            inflow_args = {"nominal_value": de["nominal value"]}
+            inflow_args = {"nominal_capacity": de["nominal value"]}
             # get time series for node and parameter
             for col in nd["timeseries"].columns.values:
                 if col.split(".")[0] == de["label"]:
@@ -225,7 +225,9 @@ def create_nodes(nd=None):
                     label=t["label"],
                     inputs={busd[t["from"]]: solph.Flow(**inflow_args)},
                     outputs={
-                        busd[t["to"]]: solph.Flow(nominal_value=t["capacity"])
+                        busd[t["to"]]: solph.Flow(
+                            nominal_capacity=t["capacity"]
+                        )
                     },
                     conversion_factors={busd[t["to"]]: t["efficiency"]},
                 )
@@ -238,13 +240,13 @@ def create_nodes(nd=None):
                     label=s["label"],
                     inputs={
                         busd[s["bus"]]: solph.Flow(
-                            nominal_value=s["capacity inflow"],
+                            nominal_capacity=s["capacity inflow"],
                             variable_costs=s["variable input costs"],
                         )
                     },
                     outputs={
                         busd[s["bus"]]: solph.Flow(
-                            nominal_value=s["capacity outflow"],
+                            nominal_capacity=s["capacity outflow"],
                             variable_costs=s["variable output costs"],
                         )
                     },
diff --git a/examples/flexible_modelling/add_constraints.py b/examples/flexible_modelling/add_constraints.py
index 1f1efceab..375b49735 100644
--- a/examples/flexible_modelling/add_constraints.py
+++ b/examples/flexible_modelling/add_constraints.py
@@ -69,18 +69,18 @@ def run_add_constraints_example(solver="cbc", nologg=False):
 
     sink = cmp.Sink(
         label="Sink",
-        inputs={b_el: Flow(nominal_value=40, fix=[0.5, 0.4, 0.3, 1])},
+        inputs={b_el: Flow(nominal_capacity=40, fix=[0.5, 0.4, 0.3, 1])},
     )
     pp_oil = cmp.Converter(
         label="pp_oil",
         inputs={boil: Flow()},
-        outputs={b_el: Flow(nominal_value=50, variable_costs=25)},
+        outputs={b_el: Flow(nominal_capacity=50, variable_costs=25)},
         conversion_factors={b_el: 0.39},
     )
     pp_lig = cmp.Converter(
         label="pp_lig",
         inputs={blig: Flow()},
-        outputs={b_el: Flow(nominal_value=50, variable_costs=10)},
+        outputs={b_el: Flow(nominal_capacity=50, variable_costs=10)},
         conversion_factors={b_el: 0.41},
     )
 
diff --git a/examples/flexible_modelling/saturating_storage.py b/examples/flexible_modelling/saturating_storage.py
index 46f9d7730..757e685bb 100644
--- a/examples/flexible_modelling/saturating_storage.py
+++ b/examples/flexible_modelling/saturating_storage.py
@@ -50,7 +50,7 @@ def saturating_storage_example():
     es.add(
         solph.components.Source(
             label="source_el",
-            outputs={bel: solph.Flow(nominal_value=1, fix=1)},
+            outputs={bel: solph.Flow(nominal_capacity=1, fix=1)},
         )
     )
 
@@ -59,7 +59,7 @@ def saturating_storage_example():
             label="sink_el",
             inputs={
                 bel: solph.Flow(
-                    nominal_value=1,
+                    nominal_capacity=1,
                     variable_costs=1,
                 )
             },
@@ -74,7 +74,7 @@ def saturating_storage_example():
     battery = solph.components.GenericStorage(
         label="battery",
         nominal_storage_capacity=storage_capacity,
-        inputs={bel: solph.Flow(nominal_value=inflow_capacity)},
+        inputs={bel: solph.Flow(nominal_capacity=inflow_capacity)},
         outputs={bel: solph.Flow(variable_costs=2)},
         initial_storage_level=0,
         balanced=False,
diff --git a/examples/flow_count_limit/flow_count_limit.py b/examples/flow_count_limit/flow_count_limit.py
index 210d85052..b8a25fd47 100644
--- a/examples/flow_count_limit/flow_count_limit.py
+++ b/examples/flow_count_limit/flow_count_limit.py
@@ -71,7 +71,7 @@ def main():
             outputs={
                 bel: solph.Flow(
                     nonconvex=solph.NonConvex(),
-                    nominal_value=210,
+                    nominal_capacity=210,
                     variable_costs=[-1, -5, -1, -1],
                     max=[1, 1, 1, 0],
                     custom_attributes={"my_keyword": True},
@@ -88,7 +88,7 @@ def main():
                 bel: solph.Flow(
                     nonconvex=solph.NonConvex(),
                     variable_costs=[-2, -1, -2, -2],
-                    nominal_value=250,
+                    nominal_capacity=250,
                     max=[1, 1, 1, 0],
                     custom_attributes={"my_keyword": False},
                 )
@@ -105,7 +105,7 @@ def main():
                     variable_costs=1,
                     nonconvex=solph.NonConvex(),
                     max=[1, 1, 1, 0],
-                    nominal_value=145,
+                    nominal_capacity=145,
                 )
             },
         )
@@ -119,7 +119,7 @@ def main():
                 bel: solph.Flow(
                     custom_attributes={"my_keyword": True},
                     fix=[0, 1, 1, 0],
-                    nominal_value=130,
+                    nominal_capacity=130,
                 )
             },
         )
diff --git a/examples/generic_invest_limit/example_generic_invest.py b/examples/generic_invest_limit/example_generic_invest.py
index a428f9c8f..a7b3a397e 100644
--- a/examples/generic_invest_limit/example_generic_invest.py
+++ b/examples/generic_invest_limit/example_generic_invest.py
@@ -105,7 +105,7 @@ def main():
     es.add(
         solph.components.Sink(
             label="demand_a",
-            inputs={bus_a_1: solph.Flow(fix=data, nominal_value=1)},
+            inputs={bus_a_1: solph.Flow(fix=data, nominal_capacity=1)},
         )
     )
 
@@ -130,7 +130,7 @@ def main():
     es.add(
         solph.components.Sink(
             label="demand_b",
-            inputs={bus_b_1: solph.Flow(fix=data, nominal_value=1)},
+            inputs={bus_b_1: solph.Flow(fix=data, nominal_capacity=1)},
         )
     )
 
@@ -141,7 +141,7 @@ def main():
             inputs={bus_a_0: solph.Flow()},
             outputs={
                 bus_a_1: solph.Flow(
-                    nominal_value=solph.Investment(
+                    nominal_capacity=solph.Investment(
                         ep_costs=epc_invest,
                         custom_attributes={"space": 2},
                     ),
@@ -158,7 +158,7 @@ def main():
             inputs={bus_b_0: solph.Flow()},
             outputs={
                 bus_b_1: solph.Flow(
-                    nominal_value=solph.Investment(
+                    nominal_capacity=solph.Investment(
                         ep_costs=epc_invest,
                         custom_attributes={"space": 1},
                     ),
diff --git a/examples/gradient_example/gradient_example.py b/examples/gradient_example/gradient_example.py
index c1f7f58cb..b50269a1a 100644
--- a/examples/gradient_example/gradient_example.py
+++ b/examples/gradient_example/gradient_example.py
@@ -131,7 +131,7 @@ def main():
     energysystem.add(
         cmp.Sink(
             label="demand",
-            inputs={bel: flows.Flow(fix=demand, nominal_value=1)},
+            inputs={bel: flows.Flow(fix=demand, nominal_capacity=1)},
         )
     )
 
@@ -142,7 +142,7 @@ def main():
             inputs={bgas: flows.Flow()},
             outputs={
                 bel: flows.Flow(
-                    nominal_value=10e5,
+                    nominal_capacity=10e5,
                     negative_gradient_limit=gradient,
                     positive_gradient_limit=gradient,
                 )
diff --git a/examples/invest_nonconvex_flow_examples/diesel_genset_nonconvex_investment.py b/examples/invest_nonconvex_flow_examples/diesel_genset_nonconvex_investment.py
index 9ea6dfa30..60f12b7e9 100644
--- a/examples/invest_nonconvex_flow_examples/diesel_genset_nonconvex_investment.py
+++ b/examples/invest_nonconvex_flow_examples/diesel_genset_nonconvex_investment.py
@@ -132,7 +132,7 @@ def main():
         outputs={
             b_el_dc: solph.flows.Flow(
                 fix=solar_potential / peak_solar_potential,
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     ep_costs=epc_pv * n_days / n_days_in_year
                 ),
                 variable_costs=0,
@@ -159,7 +159,7 @@ def main():
                 variable_costs=variable_cost_diesel_genset,
                 min=min_load,
                 max=max_load,
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     ep_costs=epc_diesel_genset * n_days / n_days_in_year,
                     maximum=2 * peak_demand,
                 ),
@@ -175,7 +175,7 @@ def main():
         label="rectifier",
         inputs={
             b_el_ac: solph.flows.Flow(
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     ep_costs=epc_rectifier * n_days / n_days_in_year
                 ),
                 variable_costs=0,
@@ -193,7 +193,7 @@ def main():
         label="inverter",
         inputs={
             b_el_dc: solph.flows.Flow(
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     ep_costs=epc_inverter * n_days / n_days_in_year
                 ),
                 variable_costs=0,
@@ -215,7 +215,7 @@ def main():
         inputs={b_el_dc: solph.flows.Flow(variable_costs=0)},
         outputs={
             b_el_dc: solph.flows.Flow(
-                nominal_value=solph.Investment(ep_costs=0)
+                nominal_capacity=solph.Investment(ep_costs=0)
             )
         },
         initial_storage_level=0.0,
@@ -234,7 +234,7 @@ def main():
         inputs={
             b_el_ac: solph.flows.Flow(
                 fix=hourly_demand / peak_demand,
-                nominal_value=peak_demand,
+                nominal_capacity=peak_demand,
             )
         },
     )
diff --git a/examples/invest_nonconvex_flow_examples/house_with_nonconvex_investment.py b/examples/invest_nonconvex_flow_examples/house_with_nonconvex_investment.py
index ba50494ab..2d9f345ef 100644
--- a/examples/invest_nonconvex_flow_examples/house_with_nonconvex_investment.py
+++ b/examples/invest_nonconvex_flow_examples/house_with_nonconvex_investment.py
@@ -71,7 +71,7 @@ def heat_demand(d):
         inputs={
             b_heat: solph.flows.Flow(
                 fix=[heat_demand(day) for day in range(0, periods)],
-                nominal_value=10,
+                nominal_capacity=10,
             )
         },
     )
@@ -91,7 +91,7 @@ def heat_demand(d):
                     minimum_uptime=5,
                     initial_status=1,
                 ),
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     ep_costs=epc,
                     minimum=1.0,
                     maximum=10.0,
@@ -104,14 +104,14 @@ def heat_demand(d):
         label="boiler",
         outputs={
             b_heat: solph.flows.Flow(
-                nominal_value=10, min=0.3, variable_costs=0.2
+                nominal_capacity=10, min=0.3, variable_costs=0.2
             )
         },
     )
 
     excess_heat = solph.components.Sink(
         label="excess_heat",
-        inputs={b_heat: solph.flows.Flow(nominal_value=10)},
+        inputs={b_heat: solph.flows.Flow(nominal_capacity=10)},
     )
 
     es.add(demand_heat, fireplace, boiler, excess_heat)
diff --git a/examples/invest_nonconvex_flow_examples/house_without_nonconvex_investment.py b/examples/invest_nonconvex_flow_examples/house_without_nonconvex_investment.py
index 15baeacf3..3c00e88f6 100644
--- a/examples/invest_nonconvex_flow_examples/house_without_nonconvex_investment.py
+++ b/examples/invest_nonconvex_flow_examples/house_without_nonconvex_investment.py
@@ -80,7 +80,7 @@ def solar_thermal(d):
         inputs={
             b_heat: solph.flows.Flow(
                 fix=[heat_demand(day) for day in range(0, periods)],
-                nominal_value=10,
+                nominal_capacity=10,
             )
         },
     )
@@ -89,7 +89,7 @@ def solar_thermal(d):
         label="fireplace",
         outputs={
             b_heat: solph.flows.Flow(
-                nominal_value=10,
+                nominal_capacity=10,
                 min=0.4,
                 max=1.0,
                 variable_costs=0.1,
@@ -104,7 +104,7 @@ def solar_thermal(d):
     boiler = solph.components.Source(
         label="boiler",
         outputs={
-            b_heat: solph.flows.Flow(nominal_value=10, variable_costs=0.2)
+            b_heat: solph.flows.Flow(nominal_capacity=10, variable_costs=0.2)
         },
     )
 
@@ -117,7 +117,7 @@ def solar_thermal(d):
         outputs={
             b_heat: solph.flows.Flow(
                 fix=[solar_thermal(day) for day in range(0, periods)],
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     ep_costs=epc, minimum=1.0, maximum=5.0
                 ),
             )
@@ -126,7 +126,7 @@ def solar_thermal(d):
 
     excess_heat = solph.components.Sink(
         label="excess_heat",
-        inputs={b_heat: solph.flows.Flow(nominal_value=10)},
+        inputs={b_heat: solph.flows.Flow(nominal_capacity=10)},
     )
 
     es.add(demand_heat, fireplace, boiler, thermal_collector, excess_heat)
diff --git a/examples/investment_with_minimal_invest/minimal_invest.py b/examples/investment_with_minimal_invest/minimal_invest.py
index 6302fa816..e48d0416f 100644
--- a/examples/investment_with_minimal_invest/minimal_invest.py
+++ b/examples/investment_with_minimal_invest/minimal_invest.py
@@ -66,7 +66,7 @@ def main():
     es.add(
         solph.components.Sink(
             label="demand",
-            inputs={bus_1: solph.Flow(fix=data, nominal_value=1)},
+            inputs={bus_1: solph.Flow(fix=data, nominal_capacity=1)},
         )
     )
 
@@ -86,7 +86,7 @@ def main():
         inputs={bus_0: solph.Flow()},
         outputs={
             bus_1: solph.Flow(
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     ep_costs=c_var,
                     maximum=p_install_max,
                     minimum=p_install_min,
diff --git a/examples/min_max_runtimes/min_max_runtimes.py b/examples/min_max_runtimes/min_max_runtimes.py
index 46a56deed..285ad5eed 100644
--- a/examples/min_max_runtimes/min_max_runtimes.py
+++ b/examples/min_max_runtimes/min_max_runtimes.py
@@ -50,7 +50,7 @@ def main():
 
     demand_el = solph.components.Sink(
         label="demand_el",
-        inputs={bel: solph.Flow(fix=demand_el, nominal_value=10)},
+        inputs={bel: solph.Flow(fix=demand_el, nominal_capacity=10)},
     )
 
     dummy_el = solph.components.Sink(
@@ -61,7 +61,7 @@ def main():
         label="plant_min_down_constraints",
         outputs={
             bel: solph.Flow(
-                nominal_value=10,
+                nominal_capacity=10,
                 min=0.5,
                 max=1.0,
                 variable_costs=10,
@@ -76,7 +76,7 @@ def main():
         label="plant_min_up_constraints",
         outputs={
             bel: solph.Flow(
-                nominal_value=10,
+                nominal_capacity=10,
                 min=0.5,
                 max=1.0,
                 variable_costs=10,
diff --git a/examples/offset_converter_example/offset_diesel_genset_nonconvex_investment.py b/examples/offset_converter_example/offset_diesel_genset_nonconvex_investment.py
index 94ebe0825..3bea2bcae 100644
--- a/examples/offset_converter_example/offset_diesel_genset_nonconvex_investment.py
+++ b/examples/offset_converter_example/offset_diesel_genset_nonconvex_investment.py
@@ -130,7 +130,7 @@ def offset_converter_example():
         outputs={
             b_el_dc: solph.flows.Flow(
                 fix=solar_potential / peak_solar_potential,
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     ep_costs=epc_pv * n_days / n_days_in_year
                 ),
                 variable_costs=0,
@@ -173,7 +173,7 @@ def offset_converter_example():
                 variable_costs=variable_cost_diesel_genset,
                 min=min_load,
                 max=max_load,
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     ep_costs=epc_diesel_genset * n_days / n_days_in_year,
                     maximum=2 * peak_demand,
                 ),
@@ -190,7 +190,7 @@ def offset_converter_example():
         label="rectifier",
         inputs={
             b_el_ac: solph.flows.Flow(
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     ep_costs=epc_rectifier * n_days / n_days_in_year
                 ),
                 variable_costs=0,
@@ -208,7 +208,7 @@ def offset_converter_example():
         label="inverter",
         inputs={
             b_el_dc: solph.flows.Flow(
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     ep_costs=epc_inverter * n_days / n_days_in_year
                 ),
                 variable_costs=0,
@@ -230,7 +230,7 @@ def offset_converter_example():
         inputs={b_el_dc: solph.flows.Flow(variable_costs=0)},
         outputs={
             b_el_dc: solph.flows.Flow(
-                nominal_value=solph.Investment(ep_costs=0)
+                nominal_capacity=solph.Investment(ep_costs=0)
             )
         },
         initial_storage_level=0.0,
@@ -249,7 +249,7 @@ def offset_converter_example():
         inputs={
             b_el_ac: solph.flows.Flow(
                 fix=hourly_demand / peak_demand,
-                nominal_value=peak_demand,
+                nominal_capacity=peak_demand,
             )
         },
     )
diff --git a/examples/simple_dispatch/simple_dispatch.py b/examples/simple_dispatch/simple_dispatch.py
index ea9e9ab66..9ade61c4a 100644
--- a/examples/simple_dispatch/simple_dispatch.py
+++ b/examples/simple_dispatch/simple_dispatch.py
@@ -108,13 +108,14 @@ def main():
     energysystem.add(
         Source(
             label="wind",
-            outputs={bel: Flow(fix=data["wind"], nominal_value=66.3)},
+            outputs={bel: Flow(fix=data["wind"], nominal_capacity=66.3)},
         )
     )
 
     energysystem.add(
         Source(
-            label="pv", outputs={bel: Flow(fix=data["pv"], nominal_value=65.3)}
+            label="pv",
+            outputs={bel: Flow(fix=data["pv"], nominal_capacity=65.3)},
         )
     )
 
@@ -122,14 +123,14 @@ def main():
     energysystem.add(
         Sink(
             label="demand_el",
-            inputs={bel: Flow(nominal_value=85, fix=data["demand_el"])},
+            inputs={bel: Flow(nominal_capacity=85, fix=data["demand_el"])},
         )
     )
 
     energysystem.add(
         Sink(
             label="demand_th",
-            inputs={bth: Flow(nominal_value=40, fix=data["demand_th"])},
+            inputs={bth: Flow(nominal_capacity=40, fix=data["demand_th"])},
         )
     )
 
@@ -138,7 +139,7 @@ def main():
         Converter(
             label="pp_coal",
             inputs={bcoal: Flow()},
-            outputs={bel: Flow(nominal_value=20.2, variable_costs=25)},
+            outputs={bel: Flow(nominal_capacity=20.2, variable_costs=25)},
             conversion_factors={bel: 0.39},
         )
     )
@@ -147,7 +148,7 @@ def main():
         Converter(
             label="pp_lig",
             inputs={blig: Flow()},
-            outputs={bel: Flow(nominal_value=11.8, variable_costs=19)},
+            outputs={bel: Flow(nominal_capacity=11.8, variable_costs=19)},
             conversion_factors={bel: 0.41},
         )
     )
@@ -156,7 +157,7 @@ def main():
         Converter(
             label="pp_gas",
             inputs={bgas: Flow()},
-            outputs={bel: Flow(nominal_value=41, variable_costs=40)},
+            outputs={bel: Flow(nominal_capacity=41, variable_costs=40)},
             conversion_factors={bel: 0.50},
         )
     )
@@ -165,7 +166,7 @@ def main():
         Converter(
             label="pp_oil",
             inputs={boil: Flow()},
-            outputs={bel: Flow(nominal_value=5, variable_costs=50)},
+            outputs={bel: Flow(nominal_capacity=5, variable_costs=50)},
             conversion_factors={bel: 0.28},
         )
     )
@@ -176,8 +177,8 @@ def main():
             label="pp_chp",
             inputs={bgas: Flow()},
             outputs={
-                bel: Flow(nominal_value=30, variable_costs=42),
-                bth: Flow(nominal_value=40),
+                bel: Flow(nominal_capacity=30, variable_costs=42),
+                bth: Flow(nominal_capacity=40),
             },
             conversion_factors={bel: 0.3, bth: 0.4},
         )
@@ -196,7 +197,7 @@ def main():
         Converter(
             label="heat_pump",
             inputs={bel: Flow(), b_heat_source: Flow()},
-            outputs={bth: Flow(nominal_value=10)},
+            outputs={bth: Flow(nominal_capacity=10)},
             conversion_factors={bel: 1 / 3, b_heat_source: (cop - 1) / cop},
         )
     )
diff --git a/examples/start_and_shutdown_costs/startup_shutdown.py b/examples/start_and_shutdown_costs/startup_shutdown.py
index 47b9349b6..648a02f49 100644
--- a/examples/start_and_shutdown_costs/startup_shutdown.py
+++ b/examples/start_and_shutdown_costs/startup_shutdown.py
@@ -71,7 +71,7 @@ def main():
 
     demand_el = solph.components.Sink(
         label="demand_el",
-        inputs={bel: solph.Flow(fix=demand_el, nominal_value=10)},
+        inputs={bel: solph.Flow(fix=demand_el, nominal_capacity=10)},
     )
 
     # pp1 and pp2 are competing to serve overall 12 units load at lowest cost
@@ -81,7 +81,7 @@ def main():
     #    the start and shutdown costs of pp2 change its marginal costs
     pp1 = solph.components.Source(
         label="power_plant1",
-        outputs={bel: solph.Flow(nominal_value=10, variable_costs=10.25)},
+        outputs={bel: solph.Flow(nominal_capacity=10, variable_costs=10.25)},
     )
 
     # shutdown costs only work in combination with a minimum load
@@ -92,7 +92,7 @@ def main():
         label="power_plant2",
         outputs={
             bel: solph.Flow(
-                nominal_value=10,
+                nominal_capacity=10,
                 min=0.5,
                 max=1.0,
                 variable_costs=10,
diff --git a/examples/storage_balanced_unbalanced/storage.py b/examples/storage_balanced_unbalanced/storage.py
index 591274630..d26e8419e 100644
--- a/examples/storage_balanced_unbalanced/storage.py
+++ b/examples/storage_balanced_unbalanced/storage.py
@@ -89,7 +89,9 @@ def storage_example():
             solph.components.Source(
                 label="pv_el_{0}".format(name),
                 outputs={
-                    bel: solph.Flow(fix=timeseries["pv_el"], nominal_value=1)
+                    bel: solph.Flow(
+                        fix=timeseries["pv_el"], nominal_capacity=1
+                    )
                 },
             )
         )
@@ -99,7 +101,7 @@ def storage_example():
                 label="demand_el_{0}".format(name),
                 inputs={
                     bel: solph.Flow(
-                        fix=timeseries["demand_el"], nominal_value=1
+                        fix=timeseries["demand_el"], nominal_capacity=1
                     )
                 },
             )
diff --git a/examples/storage_costs/storage_costs.py b/examples/storage_costs/storage_costs.py
index 312c5ab49..39bfae556 100644
--- a/examples/storage_costs/storage_costs.py
+++ b/examples/storage_costs/storage_costs.py
@@ -89,13 +89,13 @@ def storage_costs_example():
         nominal_storage_capacity=10,
         inputs={
             bel: solph.Flow(
-                nominal_value=1,
+                nominal_capacity=1,
                 variable_costs=electricity_price,
             )
         },
         outputs={
             bel: solph.Flow(
-                nominal_value=1,
+                nominal_capacity=1,
                 variable_costs=-electricity_price,
             )
         },
@@ -111,13 +111,13 @@ def storage_costs_example():
         nominal_storage_capacity=10,
         inputs={
             bel: solph.Flow(
-                nominal_value=1,
+                nominal_capacity=1,
                 variable_costs=electricity_price,
             )
         },
         outputs={
             bel: solph.Flow(
-                nominal_value=1,
+                nominal_capacity=1,
                 variable_costs=-electricity_price,
             )
         },
diff --git a/examples/storage_investment/v1_invest_optimize_all_technologies.py b/examples/storage_investment/v1_invest_optimize_all_technologies.py
index 8f3749fd5..45c5a1d25 100644
--- a/examples/storage_investment/v1_invest_optimize_all_technologies.py
+++ b/examples/storage_investment/v1_invest_optimize_all_technologies.py
@@ -151,7 +151,7 @@ def main():
         outputs={
             bel: solph.Flow(
                 fix=data["wind"],
-                nominal_value=solph.Investment(ep_costs=epc_wind),
+                nominal_capacity=solph.Investment(ep_costs=epc_wind),
             )
         },
     )
@@ -161,7 +161,8 @@ def main():
         label="pv",
         outputs={
             bel: solph.Flow(
-                fix=data["pv"], nominal_value=solph.Investment(ep_costs=epc_pv)
+                fix=data["pv"],
+                nominal_capacity=solph.Investment(ep_costs=epc_pv),
             )
         },
     )
@@ -169,14 +170,14 @@ def main():
     # create simple sink object representing the electrical demand
     demand = solph.components.Sink(
         label="demand",
-        inputs={bel: solph.Flow(fix=data["demand_el"], nominal_value=1)},
+        inputs={bel: solph.Flow(fix=data["demand_el"], nominal_capacity=1)},
     )
 
     # create simple Converter object representing a gas power plant
     pp_gas = solph.components.Converter(
         label="pp_gas",
         inputs={bgas: solph.Flow()},
-        outputs={bel: solph.Flow(nominal_value=10e10, variable_costs=0)},
+        outputs={bel: solph.Flow(nominal_capacity=10e10, variable_costs=0)},
         conversion_factors={bel: 0.58},
     )
 
diff --git a/examples/storage_investment/v2_invest_optimize_only_gas_and_storage.py b/examples/storage_investment/v2_invest_optimize_only_gas_and_storage.py
index 00c251044..528059e03 100644
--- a/examples/storage_investment/v2_invest_optimize_only_gas_and_storage.py
+++ b/examples/storage_investment/v2_invest_optimize_only_gas_and_storage.py
@@ -150,26 +150,26 @@ def main():
     # create fixed source object representing wind power plants
     wind = solph.components.Source(
         label="wind",
-        outputs={bel: solph.Flow(fix=data["wind"], nominal_value=1000000)},
+        outputs={bel: solph.Flow(fix=data["wind"], nominal_capacity=1000000)},
     )
 
     # create fixed source object representing pv power plants
     pv = solph.components.Source(
         label="pv",
-        outputs={bel: solph.Flow(fix=data["pv"], nominal_value=600000)},
+        outputs={bel: solph.Flow(fix=data["pv"], nominal_capacity=600000)},
     )
 
     # create simple sink object representing the electrical demand
     demand = solph.components.Sink(
         label="demand",
-        inputs={bel: solph.Flow(fix=data["demand_el"], nominal_value=1)},
+        inputs={bel: solph.Flow(fix=data["demand_el"], nominal_capacity=1)},
     )
 
     # create simple Converter object representing a gas power plant
     pp_gas = solph.components.Converter(
         label="pp_gas",
         inputs={bgas: solph.Flow()},
-        outputs={bel: solph.Flow(nominal_value=10e10, variable_costs=0)},
+        outputs={bel: solph.Flow(nominal_capacity=10e10, variable_costs=0)},
         conversion_factors={bel: 0.58},
     )
 
diff --git a/examples/storage_investment/v3_invest_optimize_only_storage_with_fossil_share.py b/examples/storage_investment/v3_invest_optimize_only_storage_with_fossil_share.py
index f682620cf..4c254e2be 100644
--- a/examples/storage_investment/v3_invest_optimize_only_storage_with_fossil_share.py
+++ b/examples/storage_investment/v3_invest_optimize_only_storage_with_fossil_share.py
@@ -147,7 +147,7 @@ def main():
         label="rgas",
         outputs={
             bgas: solph.Flow(
-                nominal_value=fossil_share
+                nominal_capacity=fossil_share
                 * consumption_total
                 / 0.58
                 * number_timesteps
@@ -160,26 +160,26 @@ def main():
     # create fixed source object representing wind power plants
     wind = solph.components.Source(
         label="wind",
-        outputs={bel: solph.Flow(fix=data["wind"], nominal_value=1000000)},
+        outputs={bel: solph.Flow(fix=data["wind"], nominal_capacity=1000000)},
     )
 
     # create fixed source object representing pv power plants
     pv = solph.components.Source(
         label="pv",
-        outputs={bel: solph.Flow(fix=data["pv"], nominal_value=600000)},
+        outputs={bel: solph.Flow(fix=data["pv"], nominal_capacity=600000)},
     )
 
     # create simple sink object representing the electrical demand
     demand = solph.components.Sink(
         label="demand",
-        inputs={bel: solph.Flow(fix=data["demand_el"], nominal_value=1)},
+        inputs={bel: solph.Flow(fix=data["demand_el"], nominal_capacity=1)},
     )
 
     # create simple Converter object representing a gas power plant
     pp_gas = solph.components.Converter(
         label="pp_gas",
         inputs={bgas: solph.Flow()},
-        outputs={bel: solph.Flow(nominal_value=10e10, variable_costs=0)},
+        outputs={bel: solph.Flow(nominal_capacity=10e10, variable_costs=0)},
         conversion_factors={bel: 0.58},
     )
 
diff --git a/examples/storage_investment/v4_invest_optimize_all_technologies_with_fossil_share.py b/examples/storage_investment/v4_invest_optimize_all_technologies_with_fossil_share.py
index a9c3511c9..2e9264ff1 100644
--- a/examples/storage_investment/v4_invest_optimize_all_technologies_with_fossil_share.py
+++ b/examples/storage_investment/v4_invest_optimize_all_technologies_with_fossil_share.py
@@ -146,7 +146,7 @@ def main():
         label="rgas",
         outputs={
             bgas: solph.Flow(
-                nominal_value=fossil_share
+                nominal_capacity=fossil_share
                 * consumption_total
                 / 0.58
                 * number_timesteps
@@ -162,7 +162,7 @@ def main():
         outputs={
             bel: solph.Flow(
                 fix=data["wind"],
-                nominal_value=solph.Investment(ep_costs=epc_wind),
+                nominal_capacity=solph.Investment(ep_costs=epc_wind),
             )
         },
     )
@@ -172,7 +172,8 @@ def main():
         label="pv",
         outputs={
             bel: solph.Flow(
-                fix=data["pv"], nominal_value=solph.Investment(ep_costs=epc_pv)
+                fix=data["pv"],
+                nominal_capacity=solph.Investment(ep_costs=epc_pv),
             )
         },
     )
@@ -180,14 +181,14 @@ def main():
     # create simple sink object representing the electrical demand
     demand = solph.components.Sink(
         label="demand",
-        inputs={bel: solph.Flow(fix=data["demand_el"], nominal_value=1)},
+        inputs={bel: solph.Flow(fix=data["demand_el"], nominal_capacity=1)},
     )
 
     # create simple Converter object representing a gas power plant
     pp_gas = solph.components.Converter(
         label="pp_gas",
         inputs={bgas: solph.Flow()},
-        outputs={bel: solph.Flow(nominal_value=10e10, variable_costs=0)},
+        outputs={bel: solph.Flow(nominal_capacity=10e10, variable_costs=0)},
         conversion_factors={bel: 0.58},
     )
 
diff --git a/examples/storage_level_constraint/storage_level_constraint.py b/examples/storage_level_constraint/storage_level_constraint.py
index 9fd51a607..cbc237445 100644
--- a/examples/storage_level_constraint/storage_level_constraint.py
+++ b/examples/storage_level_constraint/storage_level_constraint.py
@@ -73,22 +73,24 @@ def storage_level_constraint_example():
 
     in_0 = Source(
         label="in_0",
-        outputs={multiplexer: Flow(nominal_value=0.5, variable_costs=0.15)},
+        outputs={multiplexer: Flow(nominal_capacity=0.5, variable_costs=0.15)},
     )
     es.add(in_0)
 
-    in_1 = Source(label="in_1", outputs={multiplexer: Flow(nominal_value=0.1)})
+    in_1 = Source(
+        label="in_1", outputs={multiplexer: Flow(nominal_capacity=0.1)}
+    )
     es.add(in_1)
 
     out_0 = Sink(
         label="out_0",
-        inputs={multiplexer: Flow(nominal_value=0.25, variable_costs=-0.1)},
+        inputs={multiplexer: Flow(nominal_capacity=0.25, variable_costs=-0.1)},
     )
     es.add(out_0)
 
     out_1 = Sink(
         label="out_1",
-        inputs={multiplexer: Flow(nominal_value=0.15, variable_costs=-0.1)},
+        inputs={multiplexer: Flow(nominal_capacity=0.15, variable_costs=-0.1)},
     )
     es.add(out_1)
 
diff --git a/examples/time_index_example/non_equidistant_time_step_example.py b/examples/time_index_example/non_equidistant_time_step_example.py
index 8e8d47081..02c91af34 100644
--- a/examples/time_index_example/non_equidistant_time_step_example.py
+++ b/examples/time_index_example/non_equidistant_time_step_example.py
@@ -75,7 +75,7 @@ def main():
         label="source",
         outputs={
             bus: solph.flows.Flow(
-                nominal_value=16,
+                nominal_capacity=16,
                 variable_costs=0.2,
                 max=[0, 0, 0, 0, 0, 0, 0, 1, 1],
             )
@@ -99,7 +99,7 @@ def main():
         inputs={bus: solph.flows.Flow()},
         outputs={
             bus: solph.flows.Flow(
-                nominal_value=4, max=[0, 0, 0, 0, 0, 0, 0, 1, 1]
+                nominal_capacity=4, max=[0, 0, 0, 0, 0, 0, 0, 1, 1]
             )
         },
         nominal_storage_capacity=8,
@@ -110,7 +110,7 @@ def main():
         label="sink",
         inputs={
             bus: solph.flows.Flow(
-                nominal_value=8,
+                nominal_capacity=8,
                 variable_costs=0.1,
                 fix=[0.75, 0.5, 0, 0, 1, 0, 0, 0, 0],
             )
diff --git a/examples/time_index_example/simple_time_step_example.py b/examples/time_index_example/simple_time_step_example.py
index 7a0509872..9d6cb5b07 100644
--- a/examples/time_index_example/simple_time_step_example.py
+++ b/examples/time_index_example/simple_time_step_example.py
@@ -14,7 +14,7 @@
   If the storage is balanced, this is the same storage level as in the last time
   step.
 * The nominal_value in Flows has to be interpreted in means of power: We have
-  nominal_value=0.5, but the maximum change of the storage content of an ideal
+  nominal_capacity=0.5, but the maximum change of the storage content of an ideal
   storage is 0.125.
 
 Code
@@ -60,7 +60,7 @@ def main():
         label="source",
         outputs={
             bus: solph.flows.Flow(
-                nominal_value=2,
+                nominal_capacity=2,
                 variable_costs=0.2,
                 max=[0, 0, 0, 0, 1, 0.25, 0.75, 1],
             )
@@ -77,7 +77,7 @@ def main():
         label="sink",
         inputs={
             bus: solph.flows.Flow(
-                nominal_value=2,
+                nominal_capacity=2,
                 variable_costs=0.1,
                 fix=[1, 1, 0.5, 0.5, 0, 0, 0, 0],
             )
diff --git a/examples/tuple_as_labels/tuple_as_label.py b/examples/tuple_as_labels/tuple_as_label.py
index b31fe559f..50c904851 100644
--- a/examples/tuple_as_labels/tuple_as_label.py
+++ b/examples/tuple_as_labels/tuple_as_label.py
@@ -198,7 +198,7 @@ def main():
     energysystem.add(
         comp.Source(
             label=Label("ee_source", "electricity", "wind"),
-            outputs={bel: flows.Flow(fix=data["wind"], nominal_value=2000)},
+            outputs={bel: flows.Flow(fix=data["wind"], nominal_capacity=2000)},
         )
     )
 
@@ -206,7 +206,7 @@ def main():
     energysystem.add(
         comp.Source(
             label=Label("ee_source", "electricity", "pv"),
-            outputs={bel: flows.Flow(fix=data["pv"], nominal_value=3000)},
+            outputs={bel: flows.Flow(fix=data["pv"], nominal_capacity=3000)},
         )
     )
 
@@ -215,7 +215,9 @@ def main():
         comp.Sink(
             label=Label("sink", "electricity", "demand"),
             inputs={
-                bel: flows.Flow(fix=data["demand_el"] / 1000, nominal_value=1)
+                bel: flows.Flow(
+                    fix=data["demand_el"] / 1000, nominal_capacity=1
+                )
             },
         )
     )
@@ -225,7 +227,9 @@ def main():
         comp.Converter(
             label=Label("power plant", "electricity", "gas"),
             inputs={bgas: flows.Flow()},
-            outputs={bel: flows.Flow(nominal_value=10000, variable_costs=50)},
+            outputs={
+                bel: flows.Flow(nominal_capacity=10000, variable_costs=50)
+            },
             conversion_factors={bel: 0.58},
         )
     )
@@ -235,8 +239,12 @@ def main():
     storage = comp.GenericStorage(
         nominal_storage_capacity=nominal_storage_capacity,
         label=Label("storage", "electricity", "battery"),
-        inputs={bel: flows.Flow(nominal_value=nominal_storage_capacity / 6)},
-        outputs={bel: flows.Flow(nominal_value=nominal_storage_capacity / 6)},
+        inputs={
+            bel: flows.Flow(nominal_capacity=nominal_storage_capacity / 6)
+        },
+        outputs={
+            bel: flows.Flow(nominal_capacity=nominal_storage_capacity / 6)
+        },
         loss_rate=0.00,
         initial_storage_level=None,
         inflow_conversion_factor=1,
diff --git a/examples/variable_chp/variable_chp.py b/examples/variable_chp/variable_chp.py
index 8561c3c32..03b2d905c 100644
--- a/examples/variable_chp/variable_chp.py
+++ b/examples/variable_chp/variable_chp.py
@@ -176,13 +176,15 @@ def main():
     noded["demand_elec"] = solph.components.Sink(
         label="demand_elec",
         inputs={
-            noded["bel"]: solph.Flow(fix=data["demand_el"], nominal_value=1)
+            noded["bel"]: solph.Flow(fix=data["demand_el"], nominal_capacity=1)
         },
     )
     noded["demand_el_2"] = solph.components.Sink(
         label="demand_el_2",
         inputs={
-            noded["bel2"]: solph.Flow(fix=data["demand_el"], nominal_value=1)
+            noded["bel2"]: solph.Flow(
+                fix=data["demand_el"], nominal_capacity=1
+            )
         },
     )
 
@@ -191,7 +193,7 @@ def main():
         label="demand_therm",
         inputs={
             noded["bth"]: solph.Flow(
-                fix=data["demand_th"], nominal_value=741000
+                fix=data["demand_th"], nominal_capacity=741000
             )
         },
     )
@@ -199,7 +201,7 @@ def main():
         label="demand_th_2",
         inputs={
             noded["bth2"]: solph.Flow(
-                fix=data["demand_th"], nominal_value=741000
+                fix=data["demand_th"], nominal_capacity=741000
             )
         },
     )
@@ -207,7 +209,7 @@ def main():
     # This is just a dummy Converter with a nominal input of zero
     noded["fixed_chp_gas"] = solph.components.Converter(
         label="fixed_chp_gas",
-        inputs={noded["bgas"]: solph.Flow(nominal_value=0)},
+        inputs={noded["bgas"]: solph.Flow(nominal_capacity=0)},
         outputs={noded["bel"]: solph.Flow(), noded["bth"]: solph.Flow()},
         conversion_factors={noded["bel"]: 0.3, noded["bth"]: 0.5},
     )
@@ -215,7 +217,7 @@ def main():
     # create a fixed Converter to distribute to the heat_2 and elec_2 buses
     noded["fixed_chp_gas_2"] = solph.components.Converter(
         label="fixed_chp_gas_2",
-        inputs={noded["bgas"]: solph.Flow(nominal_value=10e10)},
+        inputs={noded["bgas"]: solph.Flow(nominal_capacity=10e10)},
         outputs={noded["bel2"]: solph.Flow(), noded["bth2"]: solph.Flow()},
         conversion_factors={noded["bel2"]: 0.3, noded["bth2"]: 0.5},
     )
@@ -223,7 +225,7 @@ def main():
     # create a fixed Converter to distribute to the heat and elec buses
     noded["variable_chp_gas"] = solph.components.ExtractionTurbineCHP(
         label="variable_chp_gas",
-        inputs={noded["bgas"]: solph.Flow(nominal_value=10e10)},
+        inputs={noded["bgas"]: solph.Flow(nominal_capacity=10e10)},
         outputs={noded["bel"]: solph.Flow(), noded["bth"]: solph.Flow()},
         conversion_factors={noded["bel"]: 0.3, noded["bth"]: 0.5},
         conversion_factor_full_condensation={noded["bel"]: 0.5},
diff --git a/src/oemof/solph/_console_scripts.py b/src/oemof/solph/_console_scripts.py
index ecc15c77b..0eccd6840 100644
--- a/src/oemof/solph/_console_scripts.py
+++ b/src/oemof/solph/_console_scripts.py
@@ -34,14 +34,14 @@ def _check_oemof_installation(solvers):
     solph.components.Sink(
         label="demand",
         inputs={
-            bel: solph.flows.Flow(fix=[10, 20, 30, 40, 50], nominal_value=1)
+            bel: solph.flows.Flow(fix=[10, 20, 30, 40, 50], nominal_capacity=1)
         },
     )
     solph.components.Converter(
         label="pp_gas",
         inputs={bgas: solph.flows.Flow()},
         outputs={
-            bel: solph.flows.Flow(nominal_value=10e10, variable_costs=50)
+            bel: solph.flows.Flow(nominal_capacity=10e10, variable_costs=50)
         },
         conversion_factors={bel: 0.58},
     )
diff --git a/src/oemof/solph/components/_extraction_turbine_chp.py b/src/oemof/solph/components/_extraction_turbine_chp.py
index cef1a6152..e6ed731db 100644
--- a/src/oemof/solph/components/_extraction_turbine_chp.py
+++ b/src/oemof/solph/components/_extraction_turbine_chp.py
@@ -64,7 +64,7 @@ class ExtractionTurbineCHP(Converter):
     >>> bgas = solph.buses.Bus(label='commodityBus')
     >>> et_chp = solph.components.ExtractionTurbineCHP(
     ...    label='variable_chp_gas',
-    ...    inputs={bgas: solph.flows.Flow(nominal_value=10e10)},
+    ...    inputs={bgas: solph.flows.Flow(nominal_capacity=10e10)},
     ...    outputs={bel: solph.flows.Flow(), bth: solph.flows.Flow()},
     ...    conversion_factors={bel: 0.3, bth: 0.5},
     ...    conversion_factor_full_condensation={bel: 0.5})
diff --git a/src/oemof/solph/components/_generic_storage.py b/src/oemof/solph/components/_generic_storage.py
index 62a04dc87..f8fd76df7 100644
--- a/src/oemof/solph/components/_generic_storage.py
+++ b/src/oemof/solph/components/_generic_storage.py
@@ -141,8 +141,8 @@ class GenericStorage(Node):
     >>> my_storage = solph.components.GenericStorage(
     ...     label='storage',
     ...     nominal_storage_capacity=1000,
-    ...     inputs={my_bus: solph.flows.Flow(nominal_value=200, variable_costs=10)},
-    ...     outputs={my_bus: solph.flows.Flow(nominal_value=200)},
+    ...     inputs={my_bus: solph.flows.Flow(nominal_capacity=200, variable_costs=10)},
+    ...     outputs={my_bus: solph.flows.Flow(nominal_capacity=200)},
     ...     loss_rate=0.01,
     ...     initial_storage_level=0,
     ...     max_storage_level = 0.9,
diff --git a/src/oemof/solph/components/_link.py b/src/oemof/solph/components/_link.py
index d5ca435c4..b6042c91a 100644
--- a/src/oemof/solph/components/_link.py
+++ b/src/oemof/solph/components/_link.py
@@ -60,8 +60,8 @@ class Link(Node):
 
     >>> link = solph.components.Link(
     ...    label="transshipment_link",
-    ...    inputs={bel0: solph.flows.Flow(nominal_value=4),
-    ...            bel1: solph.flows.Flow(nominal_value=2)},
+    ...    inputs={bel0: solph.flows.Flow(nominal_capacity=4),
+    ...            bel1: solph.flows.Flow(nominal_capacity=2)},
     ...    outputs={bel0: solph.flows.Flow(),
     ...             bel1: solph.flows.Flow()},
     ...    conversion_factors={(bel0, bel1): 0.8, (bel1, bel0): 0.9})
diff --git a/src/oemof/solph/components/_offset_converter.py b/src/oemof/solph/components/_offset_converter.py
index b078c9ced..b33442f6c 100644
--- a/src/oemof/solph/components/_offset_converter.py
+++ b/src/oemof/solph/components/_offset_converter.py
@@ -108,7 +108,7 @@ class OffsetConverter(Node):
     ...    label='ostf',
     ...    inputs={bel: solph.flows.Flow()},
     ...    outputs={bth: solph.flows.Flow(
-    ...         nominal_value=l_nominal, min=l_min, max=l_max,
+    ...         nominal_capacity=l_nominal, min=l_min, max=l_max,
     ...         nonconvex=solph.NonConvex())},
     ...    conversion_factors={bel: slope},
     ...    normed_offsets={bel: offset},
diff --git a/src/oemof/solph/components/experimental/_piecewise_linear_converter.py b/src/oemof/solph/components/experimental/_piecewise_linear_converter.py
index 666dfd701..ef2e5192b 100644
--- a/src/oemof/solph/components/experimental/_piecewise_linear_converter.py
+++ b/src/oemof/solph/components/experimental/_piecewise_linear_converter.py
@@ -54,7 +54,7 @@ class PiecewiseLinearConverter(Node):
     >>> pwltf = solph.components.experimental.PiecewiseLinearConverter(
     ...    label='pwltf',
     ...    inputs={b_gas: solph.flows.Flow(
-    ...    nominal_value=100,
+    ...    nominal_capacity=100,
     ...    variable_costs=1)},
     ...    outputs={b_el: solph.flows.Flow()},
     ...    in_breakpoints=[0,25,50,75,100],
diff --git a/src/oemof/solph/constraints/equate_variables.py b/src/oemof/solph/constraints/equate_variables.py
index 52237830d..0238a2896 100644
--- a/src/oemof/solph/constraints/equate_variables.py
+++ b/src/oemof/solph/constraints/equate_variables.py
@@ -74,12 +74,12 @@ def equate_variables(model, var1, var2, factor1=1, name=None):
     ...    label='powerline_1_2',
     ...    inputs={bel1: solph.flows.Flow()},
     ...    outputs={bel2: solph.flows.Flow(
-    ...        nominal_value=solph.Investment(ep_costs=20))}))
+    ...        nominal_capacity=solph.Investment(ep_costs=20))}))
     >>> energysystem.add(solph.components.Converter(
     ...    label='powerline_2_1',
     ...    inputs={bel2: solph.flows.Flow()},
     ...    outputs={bel1: solph.flows.Flow(
-    ...        nominal_value=solph.Investment(ep_costs=20))}))
+    ...        nominal_capacity=solph.Investment(ep_costs=20))}))
     >>> om = solph.Model(energysystem)
     >>> line12 = energysystem.groups['powerline_1_2']
     >>> line21 = energysystem.groups['powerline_2_1']
diff --git a/src/oemof/solph/constraints/integral_limit.py b/src/oemof/solph/constraints/integral_limit.py
index 0544226db..38d09ec58 100644
--- a/src/oemof/solph/constraints/integral_limit.py
+++ b/src/oemof/solph/constraints/integral_limit.py
@@ -127,10 +127,10 @@ def generic_integral_limit(
     ... )
     >>> bel = solph.buses.Bus(label='electricityBus')
     >>> flow1 = solph.flows.Flow(
-    ...     nominal_value=100,
+    ...     nominal_capacity=100,
     ...     custom_attributes={"my_factor": 0.8},
     ... )
-    >>> flow2 = solph.flows.Flow(nominal_value=50)
+    >>> flow2 = solph.flows.Flow(nominal_capacity=50)
     >>> src1 = solph.components.Source(label='source1', outputs={bel: flow1})
     >>> src2 = solph.components.Source(label='source2', outputs={bel: flow2})
     >>> energysystem.add(bel, src1, src2)
diff --git a/src/oemof/solph/constraints/investment_limit.py b/src/oemof/solph/constraints/investment_limit.py
index 1d3b62454..abb6ec9fe 100644
--- a/src/oemof/solph/constraints/investment_limit.py
+++ b/src/oemof/solph/constraints/investment_limit.py
@@ -178,16 +178,16 @@ def additional_investment_flow_limit(model, keyword, limit=None):
     ... )
     >>> bus = solph.buses.Bus(label='bus_1')
     >>> sink = solph.components.Sink(label="sink", inputs={bus:
-    ...     solph.flows.Flow(nominal_value=10, fix=[10, 20, 30, 40, 50])})
+    ...     solph.flows.Flow(nominal_capacity=10, fix=[10, 20, 30, 40, 50])})
     >>> src1 = solph.components.Source(
     ...     label='source_0', outputs={bus: solph.flows.Flow(
-    ...         nominal_value=solph.Investment(
+    ...         nominal_capacity=solph.Investment(
     ...             ep_costs=50, custom_attributes={"space": 4},
     ...         ))
     ...     })
     >>> src2 = solph.components.Source(
     ...     label='source_1', outputs={bus: solph.flows.Flow(
-    ...         nominal_value=solph.Investment(
+    ...         nominal_capacity=solph.Investment(
     ...              ep_costs=100, custom_attributes={"space": 1},
     ...         ))
     ...     })
diff --git a/src/oemof/solph/flows/experimental/_electrical_line.py b/src/oemof/solph/flows/experimental/_electrical_line.py
index 2b5e2eb85..8edd417f0 100644
--- a/src/oemof/solph/flows/experimental/_electrical_line.py
+++ b/src/oemof/solph/flows/experimental/_electrical_line.py
@@ -60,7 +60,7 @@ class ElectricalLine(Flow):
 
     def __init__(self, **kwargs):
         super().__init__(
-            nominal_value=kwargs.get("nominal_value"),
+            nominal_capacity=kwargs.get("nominal_value"),
             variable_costs=kwargs.get("variable_costs", 0),
             min=kwargs.get("min"),
             max=kwargs.get("max"),
diff --git a/tests/test_components.py b/tests/test_components.py
index f66230bfc..02a7b1d1e 100644
--- a/tests/test_components.py
+++ b/tests/test_components.py
@@ -70,8 +70,8 @@ def test_generic_storage_3():
     components.GenericStorage(
         label="storage4",
         nominal_storage_capacity=45,
-        inputs={bel: Flow(nominal_value=23, variable_costs=10e10)},
-        outputs={bel: Flow(nominal_value=7.5, variable_costs=10e10)},
+        inputs={bel: Flow(nominal_capacity=23, variable_costs=10e10)},
+        outputs={bel: Flow(nominal_capacity=7.5, variable_costs=10e10)},
         loss_rate=0.00,
         initial_storage_level=0,
         inflow_conversion_factor=1,
@@ -112,7 +112,9 @@ def test_generic_storage_with_non_convex_investment():
             outputs={bel: Flow()},
             invest_relation_input_capacity=1 / 6,
             invest_relation_output_capacity=1 / 6,
-            nominal_value=Investment(nonconvex=True, existing=5, maximum=25),
+            nominal_capacity=Investment(
+                nonconvex=True, existing=5, maximum=25
+            ),
         )
 
 
@@ -261,7 +263,7 @@ def test_offsetconverter_investment_not_on_nonconvex():
         b_diesel = Bus(label="bus_diesel")
         b_heat = Bus(label="bus_heat")
         components.OffsetConverter(
-            inputs={b_diesel: Flow(nominal_value=Investment(maximum=1))},
+            inputs={b_diesel: Flow(nominal_capacity=Investment(maximum=1))},
             outputs={b_heat: Flow(nonconvex=NonConvex())},
         )
 
diff --git a/tests/test_components/test_offset_converter.py b/tests/test_components/test_offset_converter.py
index 997a1140c..c094cb5d0 100644
--- a/tests/test_components/test_offset_converter.py
+++ b/tests/test_components/test_offset_converter.py
@@ -172,7 +172,7 @@ def test_custom_properties():
     bus2 = solph.Bus()
     oc = solph.components.OffsetConverter(
         inputs={
-            bus1: solph.Flow(nominal_value=2, nonconvex=solph.NonConvex())
+            bus1: solph.Flow(nominal_capacity=2, nonconvex=solph.NonConvex())
         },
         outputs={bus2: solph.Flow()},
         conversion_factors={bus2: 2},
@@ -189,7 +189,9 @@ def test_invalid_conversion_factor():
     with pytest.raises(ValueError, match="Conversion factors cannot be "):
         solph.components.OffsetConverter(
             inputs={
-                bus1: solph.Flow(nominal_value=2, nonconvex=solph.NonConvex())
+                bus1: solph.Flow(
+                    nominal_capacity=2, nonconvex=solph.NonConvex()
+                )
             },
             outputs={bus2: solph.Flow()},
             conversion_factors={
@@ -206,7 +208,9 @@ def test_invalid_normed_offset():
     with pytest.raises(ValueError, match="Normed offsets cannot be "):
         solph.components.OffsetConverter(
             inputs={
-                bus1: solph.Flow(nominal_value=2, nonconvex=solph.NonConvex())
+                bus1: solph.Flow(
+                    nominal_capacity=2, nonconvex=solph.NonConvex()
+                )
             },
             outputs={bus2: solph.Flow()},
             conversion_factors={
@@ -225,7 +229,9 @@ def test_wrong_number_of_coefficients():
     with pytest.raises(ValueError, match="Two coefficients"):
         solph.components.OffsetTransformer(
             inputs={
-                bus1: solph.Flow(nominal_value=2, nonconvex=solph.NonConvex())
+                bus1: solph.Flow(
+                    nominal_capacity=2, nonconvex=solph.NonConvex()
+                )
             },
             outputs={bus2: solph.Flow()},
             coefficients=(1, 2, 3),
@@ -474,7 +480,7 @@ def test_two_OffsetConverters_with_and_without_investment():
         outputs={
             es.groups["bus output 0"]: solph.Flow(
                 nonconvex=solph.NonConvex(),
-                nominal_value=solph.Investment(
+                nominal_capacity=solph.Investment(
                     maximum=nominal_value, ep_costs=10
                 ),
             )
@@ -528,7 +534,7 @@ def test_OffsetConverter_05x_compatibility():
         outputs={
             es.groups["bus output 0"]: solph.Flow(
                 nonconvex=solph.NonConvex(),
-                nominal_value=nominal_value,
+                nominal_capacity=nominal_value,
                 min=minimal_value / nominal_value,
             )
         },
@@ -575,7 +581,7 @@ def test_error_handling():
             outputs={
                 output_bus: solph.Flow(
                     nonconvex=solph.NonConvex(),
-                    nominal_value=10,
+                    nominal_capacity=10,
                     min=0.3,
                 )
             },
@@ -595,7 +601,7 @@ def test_error_handling():
                 outputs={
                     output_bus: solph.Flow(
                         nonconvex=solph.NonConvex(),
-                        nominal_value=10,
+                        nominal_capacity=10,
                         min=0.3,
                     )
                 },
@@ -612,7 +618,7 @@ def test_error_handling():
                 outputs={
                     output_bus: solph.Flow(
                         nonconvex=solph.NonConvex(),
-                        nominal_value=10,
+                        nominal_capacity=10,
                         min=0.3,
                     )
                 },
diff --git a/tests/test_components/test_sink.py b/tests/test_components/test_sink.py
index fa0559650..a4bce2a26 100644
--- a/tests/test_components/test_sink.py
+++ b/tests/test_components/test_sink.py
@@ -32,7 +32,7 @@ def test_multi_input_sink():
             solph.components.Sink(
                 inputs={
                     es.node[f"bus input {i}"]: solph.Flow(
-                        nominal_value=1,
+                        nominal_capacity=1,
                         variable_costs=costs,
                     )
                     for i in range(num_in)
diff --git a/tests/test_components/test_source.py b/tests/test_components/test_source.py
index 7219639b0..cce218fc6 100644
--- a/tests/test_components/test_source.py
+++ b/tests/test_components/test_source.py
@@ -31,7 +31,7 @@ def test_multi_output_source():
             solph.components.Source(
                 outputs={
                     es.node[f"bus input {i}"]: solph.Flow(
-                        nominal_value=1,
+                        nominal_capacity=1,
                         variable_costs=costs,
                     )
                     for i in range(num_out)
diff --git a/tests/test_components/test_storage.py b/tests/test_components/test_storage.py
index 763883637..16faf3fae 100644
--- a/tests/test_components/test_storage.py
+++ b/tests/test_components/test_storage.py
@@ -66,12 +66,14 @@ def test_invest_power_uncoupled():
         "storage",
         inputs={
             bus: solph.Flow(
-                variable_costs=-1, nominal_value=solph.Investment(ep_costs=0.1)
+                variable_costs=-1,
+                nominal_capacity=solph.Investment(ep_costs=0.1),
             )
         },
         outputs={
             bus: solph.Flow(
-                variable_costs=1, nominal_value=solph.Investment(ep_costs=0.1)
+                variable_costs=1,
+                nominal_capacity=solph.Investment(ep_costs=0.1),
             )
         },
         nominal_storage_capacity=10,
@@ -110,12 +112,14 @@ def test_invest_power_coupled():
         "storage",
         inputs={
             bus: solph.Flow(
-                variable_costs=-1, nominal_value=solph.Investment(ep_costs=0.1)
+                variable_costs=-1,
+                nominal_capacity=solph.Investment(ep_costs=0.1),
             )
         },
         outputs={
             bus: solph.Flow(
-                variable_costs=1, nominal_value=solph.Investment(ep_costs=0.1)
+                variable_costs=1,
+                nominal_capacity=solph.Investment(ep_costs=0.1),
             )
         },
         nominal_storage_capacity=10,
@@ -153,8 +157,8 @@ def test_storage_charging():
 
     storage = solph.components.GenericStorage(
         "storage",
-        inputs={bus: solph.Flow(nominal_value=2, variable_costs=-2)},
-        outputs={bus: solph.Flow(nominal_value=0.1)},
+        inputs={bus: solph.Flow(nominal_capacity=2, variable_costs=-2)},
+        outputs={bus: solph.Flow(nominal_capacity=0.1)},
         nominal_storage_capacity=19,
         initial_storage_level=0,
         balanced=False,
@@ -188,8 +192,8 @@ def test_invest_content_uncoupled():
 
     storage = solph.components.GenericStorage(
         "storage",
-        inputs={bus: solph.Flow(nominal_value=2, variable_costs=-2)},
-        outputs={bus: solph.Flow(nominal_value=0.1)},
+        inputs={bus: solph.Flow(nominal_capacity=2, variable_costs=-2)},
+        outputs={bus: solph.Flow(nominal_capacity=0.1)},
         nominal_storage_capacity=solph.Investment(
             ep_costs=0.1,
         ),
@@ -228,8 +232,8 @@ def test_invest_content_minimum():
 
     storage = solph.components.GenericStorage(
         "storage",
-        inputs={bus: solph.Flow(nominal_value=2, variable_costs=-2)},
-        outputs={bus: solph.Flow(nominal_value=0.1, variable_costs=0.1)},
+        inputs={bus: solph.Flow(nominal_capacity=2, variable_costs=-2)},
+        outputs={bus: solph.Flow(nominal_capacity=0.1, variable_costs=0.1)},
         nominal_storage_capacity=solph.Investment(
             ep_costs=0.1,
             minimum=32,
@@ -269,8 +273,8 @@ def test_invest_content_minimum_nonconvex():
 
     storage = solph.components.GenericStorage(
         "storage",
-        inputs={bus: solph.Flow(nominal_value=2, variable_costs=0.1)},
-        outputs={bus: solph.Flow(nominal_value=0.1, variable_costs=0.1)},
+        inputs={bus: solph.Flow(nominal_capacity=2, variable_costs=0.1)},
+        outputs={bus: solph.Flow(nominal_capacity=0.1, variable_costs=0.1)},
         nominal_storage_capacity=solph.Investment(
             ep_costs=0.1,
             minimum=32,
@@ -312,11 +316,11 @@ def test_invest_content_maximum():
         "storage",
         inputs={
             bus: solph.Flow(
-                nominal_value=2,
+                nominal_capacity=2,
                 variable_costs=[-2 + i * 0.01 for i in range(0, 11)],
             )
         },
-        outputs={bus: solph.Flow(nominal_value=0.1, variable_costs=0.1)},
+        outputs={bus: solph.Flow(nominal_capacity=0.1, variable_costs=0.1)},
         nominal_storage_capacity=solph.Investment(
             ep_costs=0.1,
             maximum=10,
diff --git a/tests/test_constraints/test_constraints_module.py b/tests/test_constraints/test_constraints_module.py
index 6a36b7049..30283a526 100644
--- a/tests/test_constraints/test_constraints_module.py
+++ b/tests/test_constraints/test_constraints_module.py
@@ -26,7 +26,7 @@ def test_integral_limit():
     )
     bel = solph.buses.Bus(label="electricityBus", balanced=False)
     flow1 = solph.flows.Flow(
-        nominal_value=100,
+        nominal_capacity=100,
         custom_attributes={
             "my_factor": integral_weight1,
             "emission_factor": emission_factor_low,
@@ -34,11 +34,11 @@ def test_integral_limit():
         variable_costs=-1,
     )
     flow2 = solph.flows.Flow(
-        nominal_value=50,
+        nominal_capacity=50,
         variable_costs=-0.5,
     )
     flow3 = solph.flows.Flow(
-        nominal_value=100,
+        nominal_capacity=100,
         custom_attributes={
             "my_factor": integral_weight3,
             "emission_factor": emission_factor_low,
@@ -46,7 +46,7 @@ def test_integral_limit():
         variable_costs=-0.5,
     )
     flow4 = solph.flows.Flow(
-        nominal_value=500,
+        nominal_capacity=500,
         custom_attributes={
             "emission_factor": emission_factor_high,
         },
diff --git a/tests/test_constraints/test_equate_flows.py b/tests/test_constraints/test_equate_flows.py
index 33d76e2a0..7dc5c3e7b 100644
--- a/tests/test_constraints/test_equate_flows.py
+++ b/tests/test_constraints/test_equate_flows.py
@@ -28,7 +28,7 @@ def test_equate_flows():
             b1: solph.Flow(
                 variable_costs=-0.5,
                 max=[0.5, 1],
-                nominal_value=4,
+                nominal_capacity=4,
                 custom_attributes={"keyword1": "group 1"},
             )
         },
@@ -38,7 +38,7 @@ def test_equate_flows():
         inputs={
             b1: solph.Flow(
                 variable_costs=0.1,
-                nominal_value=2,
+                nominal_capacity=2,
                 custom_attributes={"keyword2": "group 2"},
             )
         },
@@ -48,7 +48,7 @@ def test_equate_flows():
         inputs={
             b1: solph.Flow(
                 variable_costs=0.2,
-                nominal_value=3,
+                nominal_capacity=3,
                 custom_attributes={"keyword2": "group 2"},
             )
         },
@@ -58,7 +58,7 @@ def test_equate_flows():
         inputs={
             b1: solph.Flow(
                 variable_costs=0.2,
-                nominal_value=3,
+                nominal_capacity=3,
                 custom_attributes={"keyword3": "no group"},
             )
         },
diff --git a/tests/test_constraints/test_flow_count_limit.py b/tests/test_constraints/test_flow_count_limit.py
index 9b53300c6..89e6678e2 100644
--- a/tests/test_constraints/test_flow_count_limit.py
+++ b/tests/test_constraints/test_flow_count_limit.py
@@ -27,7 +27,7 @@ def test_flow_count_limit():
         inputs={
             b1: solph.Flow(
                 variable_costs=[-0.5, 0.5],
-                nominal_value=4,
+                nominal_capacity=4,
                 min=0.5,
                 nonconvex=solph.NonConvex(),
                 custom_attributes={"keyword1": "group 1"},
@@ -39,7 +39,7 @@ def test_flow_count_limit():
         inputs={
             b1: solph.Flow(
                 variable_costs=[-0.2, 0.2],
-                nominal_value=2,
+                nominal_capacity=2,
                 min=0.5,
                 nonconvex=solph.NonConvex(),
                 custom_attributes={"keyword1": "also group 1"},
@@ -51,7 +51,7 @@ def test_flow_count_limit():
         inputs={
             b1: solph.Flow(
                 variable_costs=[-0.1, 0.1],
-                nominal_value=3,
+                nominal_capacity=3,
                 min=0.5,
                 nonconvex=solph.NonConvex(),
                 custom_attributes={"keyword1": "still group 1"},
@@ -63,7 +63,7 @@ def test_flow_count_limit():
         inputs={
             b1: solph.Flow(
                 variable_costs=[-0.1, 0.2],
-                nominal_value=3,
+                nominal_capacity=3,
                 min=0.5,
                 nonconvex=solph.NonConvex(),
                 custom_attributes={"keyword2": "not in group 1"},
diff --git a/tests/test_constraints/test_storage_level.py b/tests/test_constraints/test_storage_level.py
index 325b2e8ff..e55f7a7ed 100644
--- a/tests/test_constraints/test_storage_level.py
+++ b/tests/test_constraints/test_storage_level.py
@@ -32,28 +32,34 @@ def test_storage_level_constraint():
 
     in_100 = solph.components.Source(
         label="in_100",
-        outputs={multiplexer: solph.Flow(nominal_value=5, variable_costs=0.1)},
+        outputs={
+            multiplexer: solph.Flow(nominal_capacity=5, variable_costs=0.1)
+        },
     )
     in_050 = solph.components.Source(
         label="in_050",
-        outputs={multiplexer: solph.Flow(nominal_value=5, variable_costs=0.1)},
+        outputs={
+            multiplexer: solph.Flow(nominal_capacity=5, variable_costs=0.1)
+        },
     )
     in_000 = solph.components.Source(
         label="in_000",
-        outputs={multiplexer: solph.Flow(nominal_value=5, variable_costs=0.1)},
+        outputs={
+            multiplexer: solph.Flow(nominal_capacity=5, variable_costs=0.1)
+        },
     )
 
     out_000 = solph.components.Sink(
         label="out_000",
-        inputs={multiplexer: solph.Flow(nominal_value=5)},
+        inputs={multiplexer: solph.Flow(nominal_capacity=5)},
     )
     out_050 = solph.components.Sink(
         label="out_050",
-        inputs={multiplexer: solph.Flow(nominal_value=5)},
+        inputs={multiplexer: solph.Flow(nominal_capacity=5)},
     )
     out_100 = solph.components.Sink(
         label="out_100",
-        inputs={multiplexer: solph.Flow(nominal_value=5)},
+        inputs={multiplexer: solph.Flow(nominal_capacity=5)},
     )
     es.add(in_000, in_050, in_100, out_000, out_050, out_100)
 
diff --git a/tests/test_flows/test_flow_class.py b/tests/test_flows/test_flow_class.py
index 4ddcda1fb..cf5805d23 100644
--- a/tests/test_flows/test_flow_class.py
+++ b/tests/test_flows/test_flow_class.py
@@ -36,7 +36,7 @@ def test_summed_min_future_warning():
 
 
 def test_source_with_full_load_time_max():
-    Flow(nominal_value=1, full_load_time_max=2)
+    Flow(nominal_capacity=1, full_load_time_max=2)
 
 
 def test_nonconvex_positive_gradient_error():
@@ -74,7 +74,7 @@ def test_non_convex_negative_gradient_error():
 
 
 def test_fix_sequence():
-    flow = Flow(nominal_value=4, fix=[0.3, 0.2, 0.7])
+    flow = Flow(nominal_capacity=4, fix=[0.3, 0.2, 0.7])
 
     assert flow.fix[0] == 0.3
     assert flow.fix[1] == 0.2
diff --git a/tests/test_flows/test_non_convex_flow.py b/tests/test_flows/test_non_convex_flow.py
index d5960a898..1f8198e9d 100644
--- a/tests/test_flows/test_non_convex_flow.py
+++ b/tests/test_flows/test_non_convex_flow.py
@@ -16,7 +16,7 @@
 def test_initial_status_off():
     # negative costs but turned off initially
     flow = solph.flows.Flow(
-        nominal_value=10,
+        nominal_capacity=10,
         nonconvex=solph.NonConvex(initial_status=0, minimum_downtime=5),
         variable_costs=-1,
     )
@@ -27,7 +27,7 @@ def test_initial_status_off():
 
 def test_maximum_shutdowns():
     flow = solph.flows.Flow(
-        nominal_value=10,
+        nominal_capacity=10,
         min=0.5,
         nonconvex=solph.NonConvex(maximum_shutdowns=1),
         variable_costs=[1, -2, 1, 1, 1, -5, 1, 1, 1, -2],
@@ -39,7 +39,7 @@ def test_maximum_shutdowns():
 
 def test_maximum_startups():
     flow = solph.flows.Flow(
-        nominal_value=10,
+        nominal_capacity=10,
         min=0.5,
         nonconvex=solph.NonConvex(maximum_startups=1),
         variable_costs=[1, -4, 1, 1, 1, -5, 1, 1, 5, -3],
@@ -52,7 +52,7 @@ def test_maximum_startups():
 def test_initial_status_on():
     # positive costs but turned on initially
     flow = solph.flows.Flow(
-        nominal_value=10,
+        nominal_capacity=10,
         min=0.5,
         nonconvex=solph.NonConvex(initial_status=1, minimum_uptime=3),
         variable_costs=1,
@@ -65,7 +65,7 @@ def test_initial_status_on():
 def test_activity_costs():
     # activity costs higher then revenue for first time steps
     flow = solph.flows.Flow(
-        nominal_value=10,
+        nominal_capacity=10,
         min=0.1,
         max=[0.1] + [i * 0.1 for i in range(1, 10)],
         nonconvex=solph.NonConvex(activity_costs=9 * [1] + [10]),
@@ -79,7 +79,7 @@ def test_activity_costs():
 def test_inactivity_costs():
     # inactivity costs lower then running costs for middle time steps
     flow = solph.flows.Flow(
-        nominal_value=10,
+        nominal_capacity=10,
         min=[i * 0.1 for i in range(10)],
         nonconvex=solph.NonConvex(inactivity_costs=9 * [1] + [10]),
         variable_costs=0.45,
@@ -94,7 +94,7 @@ def test_startup_costs_start_off():
 
     # startup costs higher then effect of shutting down
     flow = solph.flows.Flow(
-        nominal_value=10,
+        nominal_capacity=10,
         min=0.1,
         nonconvex=solph.NonConvex(startup_costs=5, initial_status=0),
         variable_costs=price_pattern,
@@ -109,7 +109,7 @@ def test_startup_costs_start_on():
 
     # startup costs higher then effect of shutting down
     flow = solph.flows.Flow(
-        nominal_value=10,
+        nominal_capacity=10,
         min=0.1,
         nonconvex=solph.NonConvex(startup_costs=5, initial_status=1),
         variable_costs=price_pattern,
@@ -124,7 +124,7 @@ def test_shutdown_costs_start_on():
 
     # shutdown costs higher then effect of shutting down
     flow = solph.flows.Flow(
-        nominal_value=10,
+        nominal_capacity=10,
         min=0.1,
         nonconvex=solph.NonConvex(shutdown_costs=5, initial_status=1),
         variable_costs=price_pattern,
diff --git a/tests/test_flows/test_simple_flow.py b/tests/test_flows/test_simple_flow.py
index 8dca29043..4bc0c4b36 100644
--- a/tests/test_flows/test_simple_flow.py
+++ b/tests/test_flows/test_simple_flow.py
@@ -19,7 +19,7 @@ def test_gradient_limit():
     price_pattern = [8] + 8 * [-1] + [8]
 
     flow = solph.flows.Flow(
-        nominal_value=2,
+        nominal_capacity=2,
         variable_costs=price_pattern,
         positive_gradient_limit=0.4,
         negative_gradient_limit=0.25,
@@ -35,7 +35,7 @@ def test_full_load_time_max():
     price_pattern = [-i for i in range(11)]
 
     flow = solph.flows.Flow(
-        nominal_value=2,
+        nominal_capacity=2,
         variable_costs=price_pattern,
         full_load_time_max=4.5,
     )
@@ -48,7 +48,7 @@ def test_full_load_time_min():
     price_pattern = [i for i in range(11)]
 
     flow = solph.flows.Flow(
-        nominal_value=2,
+        nominal_capacity=2,
         variable_costs=price_pattern,
         full_load_time_min=4.5,
     )
diff --git a/tests/test_grouping.py b/tests/test_grouping.py
index c9f0c450d..fb074aebc 100644
--- a/tests/test_grouping.py
+++ b/tests/test_grouping.py
@@ -41,7 +41,7 @@ def test_investment_flow_grouping(self):
                 label="Source",
                 outputs={
                     b: solph.flows.Flow(
-                        fix=[12, 16, 14], nominal_value=1000000
+                        fix=[12, 16, 14], nominal_capacity=1000000
                     )
                 },
             )
@@ -55,7 +55,9 @@ def test_investment_flow_grouping(self):
                         full_load_time_max=2.3,
                         variable_costs=25,
                         max=0.8,
-                        nominal_value=Investment(ep_costs=500, maximum=10e5),
+                        nominal_capacity=Investment(
+                            ep_costs=500, maximum=10e5
+                        ),
                     )
                 },
             )
diff --git a/tests/test_models.py b/tests/test_models.py
index e5c51f9bd..feb982132 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -23,12 +23,14 @@ def test_infeasible_model():
     es.add(bel)
     es.add(
         solph.components.Sink(
-            inputs={bel: solph.flows.Flow(nominal_value=5, fix=[1])}
+            inputs={bel: solph.flows.Flow(nominal_capacity=5, fix=[1])}
         )
     )
     es.add(
         solph.components.Source(
-            outputs={bel: solph.flows.Flow(nominal_value=4, variable_costs=5)}
+            outputs={
+                bel: solph.flows.Flow(nominal_capacity=4, variable_costs=5)
+            }
         )
     )
     m = solph.Model(es)
@@ -60,7 +62,7 @@ def test_multi_period_default_discount_rate():
             label="sink",
             inputs={
                 bel: solph.flows.Flow(
-                    nominal_value=5, fix=[1] * len(timeindex)
+                    nominal_capacity=5, fix=[1] * len(timeindex)
                 )
             },
         )
@@ -68,7 +70,9 @@ def test_multi_period_default_discount_rate():
     es.add(
         solph.components.Source(
             label="source",
-            outputs={bel: solph.flows.Flow(nominal_value=4, variable_costs=5)},
+            outputs={
+                bel: solph.flows.Flow(nominal_capacity=4, variable_costs=5)
+            },
         )
     )
     msg = (
diff --git a/tests/test_non_equidistant_time_index.py b/tests/test_non_equidistant_time_index.py
index 1b68df738..24aed8d14 100644
--- a/tests/test_non_equidistant_time_index.py
+++ b/tests/test_non_equidistant_time_index.py
@@ -40,7 +40,7 @@ def setup_class(cls):
             inputs={b_diesel: flows.Flow(variable_costs=2)},
             outputs={
                 b_el1: flows.Flow(
-                    variable_costs=1, nominal_value=Investment(ep_costs=500)
+                    variable_costs=1, nominal_capacity=Investment(ep_costs=500)
                 )
             },
             conversion_factors={b_el1: 0.5},
@@ -64,7 +64,7 @@ def setup_class(cls):
             label="demand_el",
             inputs={
                 b_el1: flows.Flow(
-                    nominal_value=1,
+                    nominal_capacity=1,
                     fix=demand_values,
                 )
             },
diff --git a/tests/test_options.py b/tests/test_options.py
index 2b26b9d2f..b33baed83 100644
--- a/tests/test_options.py
+++ b/tests/test_options.py
@@ -16,4 +16,4 @@ def test_check_age_and_lifetime():
     """Check error being thrown if age > lifetime"""
     msg = "A unit's age must be smaller than its expected lifetime."
     with pytest.raises(AttributeError, match=msg):
-        solph.Flow(nominal_value=solph.Investment(age=41, lifetime=40))
+        solph.Flow(nominal_capacity=solph.Investment(age=41, lifetime=40))
diff --git a/tests/test_outputlib/__init__.py b/tests/test_outputlib/__init__.py
index 5e86927e3..b717b21e2 100644
--- a/tests/test_outputlib/__init__.py
+++ b/tests/test_outputlib/__init__.py
@@ -33,7 +33,7 @@
     outputs={
         bel: Flow(
             fix=data["wind"],
-            nominal_value=66.3,
+            nominal_capacity=66.3,
         )
     },
 )
@@ -43,7 +43,7 @@
     outputs={
         bel: Flow(
             fix=data["pv"],
-            nominal_value=65.3,
+            nominal_capacity=65.3,
         )
     },
 )
@@ -53,7 +53,7 @@
     label="demand_elec",
     inputs={
         bel: Flow(
-            nominal_value=85,
+            nominal_capacity=85,
             fix=data["demand_el"],
         )
     },
@@ -63,7 +63,7 @@
     label="demand_therm",
     inputs={
         bth: Flow(
-            nominal_value=40,
+            nominal_capacity=40,
             fix=data["demand_th"],
         )
     },
@@ -73,28 +73,28 @@
 pp_coal = Converter(
     label="pp_coal",
     inputs={bcoal: Flow()},
-    outputs={bel: Flow(nominal_value=20.2, variable_costs=25)},
+    outputs={bel: Flow(nominal_capacity=20.2, variable_costs=25)},
     conversion_factors={bel: 0.39},
 )
 
 pp_lig = Converter(
     label="pp_lig",
     inputs={blig: Flow()},
-    outputs={bel: Flow(nominal_value=11.8, variable_costs=19)},
+    outputs={bel: Flow(nominal_capacity=11.8, variable_costs=19)},
     conversion_factors={bel: 0.41},
 )
 
 pp_gas = Converter(
     label="pp_gas",
     inputs={bgas: Flow()},
-    outputs={bel: Flow(nominal_value=41, variable_costs=40)},
+    outputs={bel: Flow(nominal_capacity=41, variable_costs=40)},
     conversion_factors={bel: 0.50},
 )
 
 pp_oil = Converter(
     label="pp_oil",
     inputs={boil: Flow()},
-    outputs={bel: Flow(nominal_value=5, variable_costs=50)},
+    outputs={bel: Flow(nominal_capacity=5, variable_costs=50)},
     conversion_factors={bel: 0.28},
 )
 
@@ -103,8 +103,8 @@
     label="pp_chp",
     inputs={bgas: Flow()},
     outputs={
-        bel: Flow(nominal_value=30, variable_costs=42),
-        bth: Flow(nominal_value=40),
+        bel: Flow(nominal_capacity=30, variable_costs=42),
+        bth: Flow(nominal_capacity=40),
     },
     conversion_factors={bel: 0.3, bth: 0.4},
 )
@@ -118,7 +118,7 @@
 heat_pump = Converter(
     label="heat_pump",
     inputs={bel: Flow(), b_heat_source: Flow()},
-    outputs={bth: Flow(nominal_value=10)},
+    outputs={bth: Flow(nominal_capacity=10)},
     conversion_factors={bel: 1 / 3, b_heat_source: (cop - 1) / cop},
 )
 
diff --git a/tests/test_processing.py b/tests/test_processing.py
index c7b93c900..e563fece7 100644
--- a/tests/test_processing.py
+++ b/tests/test_processing.py
@@ -51,7 +51,7 @@ def setup_class(cls):
             inputs={b_diesel: Flow(variable_costs=2)},
             outputs={
                 b_el1: Flow(
-                    variable_costs=1, nominal_value=Investment(ep_costs=0.5)
+                    variable_costs=1, nominal_capacity=Investment(ep_costs=0.5)
                 )
             },
             conversion_factors={b_el1: 2},
@@ -75,7 +75,7 @@ def setup_class(cls):
             label="demand_el",
             inputs={
                 b_el2: Flow(
-                    nominal_value=1,
+                    nominal_capacity=1,
                     fix=cls.demand_values,
                 )
             },
diff --git a/tests/test_scripts/test_solph/test_connect_invest/test_connect_invest.py b/tests/test_scripts/test_solph/test_connect_invest/test_connect_invest.py
index a409177fb..7af2cab04 100644
--- a/tests/test_scripts/test_solph/test_connect_invest/test_connect_invest.py
+++ b/tests/test_scripts/test_solph/test_connect_invest/test_connect_invest.py
@@ -57,7 +57,7 @@ def test_connect_invest():
     es.add(
         components.Source(
             label="wind",
-            outputs={bel1: Flow(fix=data["wind"], nominal_value=1000000)},
+            outputs={bel1: Flow(fix=data["wind"], nominal_capacity=1000000)},
         )
     )
 
@@ -65,7 +65,7 @@ def test_connect_invest():
     es.add(
         components.Sink(
             label="demand",
-            inputs={bel1: Flow(fix=data["demand_el"], nominal_value=1)},
+            inputs={bel1: Flow(fix=data["demand_el"], nominal_capacity=1)},
         )
     )
 
@@ -86,14 +86,14 @@ def test_connect_invest():
     line12 = components.Converter(
         label="line12",
         inputs={bel1: Flow()},
-        outputs={bel2: Flow(nominal_value=Investment(ep_costs=20))},
+        outputs={bel2: Flow(nominal_capacity=Investment(ep_costs=20))},
     )
     es.add(line12)
 
     line21 = components.Converter(
         label="line21",
         inputs={bel2: Flow()},
-        outputs={bel1: Flow(nominal_value=Investment(ep_costs=20))},
+        outputs={bel1: Flow(nominal_capacity=Investment(ep_costs=20))},
     )
     es.add(line21)
 
diff --git a/tests/test_scripts/test_solph/test_flexible_modelling/test_add_constraints.py b/tests/test_scripts/test_solph/test_flexible_modelling/test_add_constraints.py
index 01a63e426..00868963d 100644
--- a/tests/test_scripts/test_solph/test_flexible_modelling/test_add_constraints.py
+++ b/tests/test_scripts/test_solph/test_flexible_modelling/test_add_constraints.py
@@ -45,13 +45,13 @@ def test_add_constraints_example(solver="cbc", nologg=False):
     es.add(
         components.Sink(
             label="Sink",
-            inputs={b_el: Flow(nominal_value=40, fix=[0.5, 0.4, 0.3, 1])},
+            inputs={b_el: Flow(nominal_capacity=40, fix=[0.5, 0.4, 0.3, 1])},
         )
     )
     pp_oil = components.Converter(
         label="pp_oil",
         inputs={boil: Flow()},
-        outputs={b_el: Flow(nominal_value=50, variable_costs=25)},
+        outputs={b_el: Flow(nominal_capacity=50, variable_costs=25)},
         conversion_factors={b_el: 0.39},
     )
 
@@ -60,7 +60,7 @@ def test_add_constraints_example(solver="cbc", nologg=False):
         components.Converter(
             label="pp_lig",
             inputs={blig: Flow()},
-            outputs={b_el: Flow(nominal_value=50, variable_costs=10)},
+            outputs={b_el: Flow(nominal_capacity=50, variable_costs=10)},
             conversion_factors={b_el: 0.41},
         )
     )
diff --git a/tests/test_scripts/test_solph/test_generic_chp/test_generic_chp.py b/tests/test_scripts/test_solph/test_generic_chp/test_generic_chp.py
index 6c9f8c423..e7b557428 100644
--- a/tests/test_scripts/test_solph/test_generic_chp/test_generic_chp.py
+++ b/tests/test_scripts/test_solph/test_generic_chp/test_generic_chp.py
@@ -59,7 +59,9 @@ def test_gen_chp():
         solph.components.Sink(
             label="demand_th",
             inputs={
-                bth: solph.flows.Flow(fix=data["demand_th"], nominal_value=200)
+                bth: solph.flows.Flow(
+                    fix=data["demand_th"], nominal_capacity=200
+                )
             },
         )
     )
diff --git a/tests/test_scripts/test_solph/test_invest_fix_flow/test_simple_invest_fixed.py b/tests/test_scripts/test_solph/test_invest_fix_flow/test_simple_invest_fixed.py
index 1a025b9a6..2a90f4e1d 100644
--- a/tests/test_scripts/test_solph/test_invest_fix_flow/test_simple_invest_fixed.py
+++ b/tests/test_scripts/test_solph/test_invest_fix_flow/test_simple_invest_fixed.py
@@ -50,14 +50,16 @@ def test_dispatch_fix_example(solver="cbc", periods=10):
     pv = Source(
         label="pv",
         outputs={
-            bel: Flow(fix=data["pv"], nominal_value=Investment(ep_costs=ep_pv))
+            bel: Flow(
+                fix=data["pv"], nominal_capacity=Investment(ep_costs=ep_pv)
+            )
         },
     )
 
     # demands (electricity/heat)
     demand_el = Sink(
         label="demand_elec",
-        inputs={bel: Flow(nominal_value=85, fix=data["demand_el"])},
+        inputs={bel: Flow(nominal_capacity=85, fix=data["demand_el"])},
     )
 
     datetimeindex = pd.date_range("1/1/2012", periods=periods, freq="h")
diff --git a/tests/test_scripts/test_solph/test_lopf/test_lopf.py b/tests/test_scripts/test_solph/test_lopf/test_lopf.py
index e831734a4..1a6246697 100644
--- a/tests/test_scripts/test_solph/test_lopf/test_lopf.py
+++ b/tests/test_scripts/test_solph/test_lopf/test_lopf.py
@@ -55,7 +55,7 @@ def test_lopf(solver="cbc"):
         input=b_el0,
         output=b_el1,
         reactance=0.0001,
-        nominal_value=Investment(ep_costs=10),
+        nominal_capacity=Investment(ep_costs=10),
         min=-1,
         max=1,
     )
@@ -64,7 +64,7 @@ def test_lopf(solver="cbc"):
         input=b_el1,
         output=b_el2,
         reactance=0.0001,
-        nominal_value=60,
+        nominal_capacity=60,
         min=-1,
         max=1,
     )
@@ -73,7 +73,7 @@ def test_lopf(solver="cbc"):
         input=b_el2,
         output=b_el0,
         reactance=0.0001,
-        nominal_value=60,
+        nominal_capacity=60,
         min=-1,
         max=1,
     )
@@ -81,21 +81,21 @@ def test_lopf(solver="cbc"):
     es.add(
         Source(
             label="gen_0",
-            outputs={b_el0: Flow(nominal_value=100, variable_costs=50)},
+            outputs={b_el0: Flow(nominal_capacity=100, variable_costs=50)},
         )
     )
 
     es.add(
         Source(
             label="gen_1",
-            outputs={b_el1: Flow(nominal_value=100, variable_costs=25)},
+            outputs={b_el1: Flow(nominal_capacity=100, variable_costs=25)},
         )
     )
 
     es.add(
         Sink(
             label="load",
-            inputs={b_el2: Flow(nominal_value=100, fix=1)},
+            inputs={b_el2: Flow(nominal_capacity=100, fix=1)},
         )
     )
 
diff --git a/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_dispatch_model.py b/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_dispatch_model.py
index c61952720..3e391938a 100644
--- a/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_dispatch_model.py
+++ b/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_dispatch_model.py
@@ -83,13 +83,15 @@ def test_multi_period_dispatch_model(solver="cbc"):
             bus_el: flows.Flow(
                 variable_costs=0,
                 fix=[110] + [90] * (len(timeindex) - 1),
-                nominal_value=1,
+                nominal_capacity=1,
             )
         },
     )
     source_shortage = components.Source(
         label="DE_source_shortage",
-        outputs={bus_el: flows.Flow(variable_costs=1e10, nominal_value=1e10)},
+        outputs={
+            bus_el: flows.Flow(variable_costs=1e10, nominal_capacity=1e10)
+        },
     )
     source_wind_fr = components.Source(
         label="FR_source_wind",
@@ -97,14 +99,14 @@ def test_multi_period_dispatch_model(solver="cbc"):
             bus_el_fr: flows.Flow(
                 variable_costs=0,
                 fix=[45] * len(timeindex),
-                nominal_value=1,
+                nominal_capacity=1,
             )
         },
     )
     source_shortage_fr = components.Source(
         label="FR_source_shortage",
         outputs={
-            bus_el_fr: flows.Flow(variable_costs=1e10, nominal_value=1e10)
+            bus_el_fr: flows.Flow(variable_costs=1e10, nominal_capacity=1e10)
         },
     )
 
@@ -112,36 +114,42 @@ def test_multi_period_dispatch_model(solver="cbc"):
     sink_el = components.Sink(
         label="DE_sink_el",
         inputs={
-            bus_el: flows.Flow(fix=[80] * len(timeindex), nominal_value=1)
+            bus_el: flows.Flow(fix=[80] * len(timeindex), nominal_capacity=1)
         },
     )
     sink_excess = components.Sink(
         label="DE_sink_excess",
-        inputs={bus_el: flows.Flow(variable_costs=1e10, nominal_value=1e10)},
+        inputs={
+            bus_el: flows.Flow(variable_costs=1e10, nominal_capacity=1e10)
+        },
     )
     sink_el_fr = components.Sink(
         label="FR_sink_el",
         inputs={
-            bus_el_fr: flows.Flow(fix=[50] * len(timeindex), nominal_value=1)
+            bus_el_fr: flows.Flow(
+                fix=[50] * len(timeindex), nominal_capacity=1
+            )
         },
     )
     sink_excess_fr = components.Sink(
         label="FR_sink_excess",
-        inputs={bus_el_fr: flows.Flow(variable_costs=1e3, nominal_value=1e10)},
+        inputs={
+            bus_el_fr: flows.Flow(variable_costs=1e3, nominal_capacity=1e10)
+        },
     )
 
     # Create converters
     pp_lignite = components.Converter(
         label="DE_pp_lignite",
         inputs={bus_lignite: flows.Flow()},
-        outputs={bus_el: flows.Flow(nominal_value=100, variable_costs=1)},
+        outputs={bus_el: flows.Flow(nominal_capacity=100, variable_costs=1)},
         conversion_factors={bus_el: 0.38},
     )
 
     pp_hardcoal = components.Converter(
         label="DE_pp_hardcoal",
         inputs={bus_hardcoal: flows.Flow()},
-        outputs={bus_el: flows.Flow(nominal_value=100, variable_costs=2)},
+        outputs={bus_el: flows.Flow(nominal_capacity=100, variable_costs=2)},
         conversion_factors={bus_el: 0.45},
     )
 
@@ -150,7 +158,7 @@ def test_multi_period_dispatch_model(solver="cbc"):
         inputs={bus_natgas: flows.Flow()},
         outputs={
             bus_el: flows.Flow(
-                nominal_value=100,
+                nominal_capacity=100,
                 variable_costs=3,
             )
         },
@@ -162,7 +170,7 @@ def test_multi_period_dispatch_model(solver="cbc"):
         inputs={bus_natgas: flows.Flow()},
         outputs={
             bus_el: flows.Flow(
-                nominal_value=100,
+                nominal_capacity=100,
                 variable_costs=4,
             )
         },
@@ -171,9 +179,11 @@ def test_multi_period_dispatch_model(solver="cbc"):
 
     storage_el = components.GenericStorage(
         label="DE_storage_el",
-        inputs={bus_el: flows.Flow(nominal_value=20, variable_costs=0, max=1)},
+        inputs={
+            bus_el: flows.Flow(nominal_capacity=20, variable_costs=0, max=1)
+        },
         outputs={
-            bus_el: flows.Flow(nominal_value=20, variable_costs=0, max=1)
+            bus_el: flows.Flow(nominal_capacity=20, variable_costs=0, max=1)
         },
         nominal_storage_capacity=20,
         loss_rate=0,
@@ -189,8 +199,8 @@ def test_multi_period_dispatch_model(solver="cbc"):
     link_de_fr = components.Link(
         label="link_DE_FR",
         inputs={
-            bus_el: flows.Flow(nominal_value=10),
-            bus_el_fr: flows.Flow(nominal_value=10),
+            bus_el: flows.Flow(nominal_capacity=10),
+            bus_el_fr: flows.Flow(nominal_capacity=10),
         },
         outputs={
             bus_el_fr: flows.Flow(),
diff --git a/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_investment_model.py b/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_investment_model.py
index 43c45834b..fcaf31c93 100644
--- a/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_investment_model.py
+++ b/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_investment_model.py
@@ -86,14 +86,14 @@ def test_multi_period_investment_model(solver="cbc"):
                 bus_el: flows.Flow(
                     variable_costs=0,
                     fix=[110] + [90] * (len(timeindex) - 1),
-                    nominal_value=1,
+                    nominal_capacity=1,
                 )
             },
         )
         source_shortage = components.Source(
             label="DE_source_shortage",
             outputs={
-                bus_el: flows.Flow(variable_costs=1e10, nominal_value=1e10)
+                bus_el: flows.Flow(variable_costs=1e10, nominal_capacity=1e10)
             },
         )
         source_wind_FR = components.Source(
@@ -102,14 +102,16 @@ def test_multi_period_investment_model(solver="cbc"):
                 bus_el_FR: flows.Flow(
                     variable_costs=0,
                     fix=[45] * len(timeindex),
-                    nominal_value=1,
+                    nominal_capacity=1,
                 )
             },
         )
         source_shortage_FR = components.Source(
             label="FR_source_shortage",
             outputs={
-                bus_el_FR: flows.Flow(variable_costs=1e10, nominal_value=1e10)
+                bus_el_FR: flows.Flow(
+                    variable_costs=1e10, nominal_capacity=1e10
+                )
             },
         )
 
@@ -117,27 +119,31 @@ def test_multi_period_investment_model(solver="cbc"):
         sink_el = components.Sink(
             label="DE_sink_el",
             inputs={
-                bus_el: flows.Flow(fix=[80] * len(timeindex), nominal_value=1)
+                bus_el: flows.Flow(
+                    fix=[80] * len(timeindex), nominal_capacity=1
+                )
             },
         )
         sink_excess = components.Sink(
             label="DE_sink_excess",
             inputs={
-                bus_el: flows.Flow(variable_costs=1e10, nominal_value=1e10)
+                bus_el: flows.Flow(variable_costs=1e10, nominal_capacity=1e10)
             },
         )
         sink_el_FR = components.Sink(
             label="FR_sink_el",
             inputs={
                 bus_el_FR: flows.Flow(
-                    fix=[50] * len(timeindex), nominal_value=1
+                    fix=[50] * len(timeindex), nominal_capacity=1
                 )
             },
         )
         sink_excess_FR = components.Sink(
             label="FR_sink_excess",
             inputs={
-                bus_el_FR: flows.Flow(variable_costs=1e3, nominal_value=1e10)
+                bus_el_FR: flows.Flow(
+                    variable_costs=1e3, nominal_capacity=1e10
+                )
             },
         )
 
@@ -147,7 +153,7 @@ def test_multi_period_investment_model(solver="cbc"):
             inputs={bus_lignite: flows.Flow()},
             outputs={
                 bus_el: flows.Flow(
-                    nominal_value=_options.Investment(
+                    nominal_capacity=_options.Investment(
                         maximum=1000,
                         ep_costs=2e6,
                         existing=0,
@@ -166,7 +172,7 @@ def test_multi_period_investment_model(solver="cbc"):
             inputs={bus_hardcoal: flows.Flow()},  # )},
             outputs={
                 bus_el: flows.Flow(
-                    nominal_value=_options.Investment(
+                    nominal_capacity=_options.Investment(
                         maximum=1000,
                         ep_costs=1.6e6,
                         existing=0,
@@ -185,7 +191,7 @@ def test_multi_period_investment_model(solver="cbc"):
             inputs={bus_natgas: flows.Flow()},  # )},
             outputs={
                 bus_el: flows.Flow(
-                    nominal_value=_options.Investment(
+                    nominal_capacity=_options.Investment(
                         maximum=1000,
                         ep_costs=1e6,
                         existing=0,
@@ -204,7 +210,7 @@ def test_multi_period_investment_model(solver="cbc"):
             inputs={bus_natgas: flows.Flow()},  # )},
             outputs={
                 bus_el: flows.Flow(
-                    nominal_value=_options.Investment(
+                    nominal_capacity=_options.Investment(
                         maximum=1000,
                         ep_costs=[0.6e6, 0.5e6, 0.8e6, 0.4e6],
                         existing=0,
@@ -225,7 +231,7 @@ def test_multi_period_investment_model(solver="cbc"):
                 bus_el: flows.Flow(
                     variable_costs=0,
                     max=1,
-                    nominal_value=_options.Investment(
+                    nominal_capacity=_options.Investment(
                         maximum=20,
                         ep_costs=1000,
                         existing=10,
@@ -239,7 +245,7 @@ def test_multi_period_investment_model(solver="cbc"):
                 bus_el: flows.Flow(
                     variable_costs=0,
                     max=1,
-                    nominal_value=_options.Investment(
+                    nominal_capacity=_options.Investment(
                         maximum=20,
                         ep_costs=1000,
                         existing=10,
@@ -274,10 +280,10 @@ def test_multi_period_investment_model(solver="cbc"):
             label="link_DE_FR",
             inputs={
                 bus_el: flows.Flow(
-                    nominal_value=10,
+                    nominal_capacity=10,
                 ),
                 bus_el_FR: flows.Flow(
-                    nominal_value=10,
+                    nominal_capacity=10,
                 ),
             },
             outputs={bus_el_FR: flows.Flow(), bus_el: flows.Flow()},
diff --git a/tests/test_scripts/test_solph/test_piecewiselineartransformer/test_piecewiselineartransformer.py b/tests/test_scripts/test_solph/test_piecewiselineartransformer/test_piecewiselineartransformer.py
index 64823a6b9..b3bf89a77 100644
--- a/tests/test_scripts/test_solph/test_piecewiselineartransformer/test_piecewiselineartransformer.py
+++ b/tests/test_scripts/test_solph/test_piecewiselineartransformer/test_piecewiselineartransformer.py
@@ -38,7 +38,7 @@ def test_pwltf():
     b_el = Bus(label="electricity")
     demand_el = Sink(
         label="demand",
-        inputs={b_el: Flow(nominal_value=1, fix=demand)},
+        inputs={b_el: Flow(nominal_capacity=1, fix=demand)},
     )
 
     energysystem.add(b_gas, b_el, demand_el)
@@ -52,7 +52,9 @@ def conv_func(x):
     # Create and add PiecewiseLinearConverter
     pwltf = solph.components.experimental.PiecewiseLinearConverter(
         label="pwltf",
-        inputs={b_gas: solph.flows.Flow(nominal_value=100, variable_costs=1)},
+        inputs={
+            b_gas: solph.flows.Flow(nominal_capacity=100, variable_costs=1)
+        },
         outputs={b_el: solph.flows.Flow()},
         in_breakpoints=in_breakpoints,
         conversion_function=conv_func,
diff --git a/tests/test_scripts/test_solph/test_simple_model/test_simple_dispatch.py b/tests/test_scripts/test_solph/test_simple_model/test_simple_dispatch.py
index e8d12b264..7705fc4c3 100644
--- a/tests/test_scripts/test_solph/test_simple_model/test_simple_dispatch.py
+++ b/tests/test_scripts/test_solph/test_simple_model/test_simple_dispatch.py
@@ -54,50 +54,51 @@ def test_dispatch_example(solver="cbc", periods=24 * 5):
 
     # sources
     wind = Source(
-        label="wind", outputs={bel: Flow(fix=data["wind"], nominal_value=66.3)}
+        label="wind",
+        outputs={bel: Flow(fix=data["wind"], nominal_capacity=66.3)},
     )
 
     pv = Source(
-        label="pv", outputs={bel: Flow(fix=data["pv"], nominal_value=65.3)}
+        label="pv", outputs={bel: Flow(fix=data["pv"], nominal_capacity=65.3)}
     )
 
     # demands (electricity/heat)
     demand_el = Sink(
         label="demand_elec",
-        inputs={bel: Flow(nominal_value=85, fix=data["demand_el"])},
+        inputs={bel: Flow(nominal_capacity=85, fix=data["demand_el"])},
     )
 
     demand_th = Sink(
         label="demand_therm",
-        inputs={bth: Flow(nominal_value=40, fix=data["demand_th"])},
+        inputs={bth: Flow(nominal_capacity=40, fix=data["demand_th"])},
     )
 
     # power plants
     pp_coal = Converter(
         label="pp_coal",
         inputs={bcoal: Flow()},
-        outputs={bel: Flow(nominal_value=20.2, variable_costs=25)},
+        outputs={bel: Flow(nominal_capacity=20.2, variable_costs=25)},
         conversion_factors={bel: 0.39},
     )
 
     pp_lig = Converter(
         label="pp_lig",
         inputs={blig: Flow()},
-        outputs={bel: Flow(nominal_value=11.8, variable_costs=19)},
+        outputs={bel: Flow(nominal_capacity=11.8, variable_costs=19)},
         conversion_factors={bel: 0.41},
     )
 
     pp_gas = Converter(
         label="pp_gas",
         inputs={bgas: Flow()},
-        outputs={bel: Flow(nominal_value=41, variable_costs=40)},
+        outputs={bel: Flow(nominal_capacity=41, variable_costs=40)},
         conversion_factors={bel: 0.50},
     )
 
     pp_oil = Converter(
         label="pp_oil",
         inputs={boil: Flow()},
-        outputs={bel: Flow(nominal_value=5, variable_costs=50)},
+        outputs={bel: Flow(nominal_capacity=5, variable_costs=50)},
         conversion_factors={bel: 0.28},
     )
 
@@ -106,8 +107,8 @@ def test_dispatch_example(solver="cbc", periods=24 * 5):
         label="pp_chp",
         inputs={bgas: Flow()},
         outputs={
-            bel: Flow(nominal_value=30, variable_costs=42),
-            bth: Flow(nominal_value=40),
+            bel: Flow(nominal_capacity=30, variable_costs=42),
+            bth: Flow(nominal_capacity=40),
         },
         conversion_factors={bel: 0.3, bth: 0.4},
     )
@@ -121,7 +122,7 @@ def test_dispatch_example(solver="cbc", periods=24 * 5):
     heat_pump = Converter(
         label="heat_pump",
         inputs={bel: Flow(), b_heat_source: Flow()},
-        outputs={bth: Flow(nominal_value=10)},
+        outputs={bth: Flow(nominal_capacity=10)},
         conversion_factors={bel: 1 / 3, b_heat_source: (cop - 1) / cop},
     )
 
diff --git a/tests/test_scripts/test_solph/test_simple_model/test_simple_dispatch_one.py b/tests/test_scripts/test_solph/test_simple_model/test_simple_dispatch_one.py
index 99a2f7478..2ba6aebbe 100644
--- a/tests/test_scripts/test_solph/test_simple_model/test_simple_dispatch_one.py
+++ b/tests/test_scripts/test_solph/test_simple_model/test_simple_dispatch_one.py
@@ -40,16 +40,16 @@ def test_dispatch_one_time_step(solver="cbc"):
 
     # sources
     wind = Source(
-        label="wind", outputs={bel: Flow(fix=0.5, nominal_value=66.3)}
+        label="wind", outputs={bel: Flow(fix=0.5, nominal_capacity=66.3)}
     )
 
     # demands (electricity/heat)
     demand_el = Sink(
-        label="demand_elec", inputs={bel: Flow(nominal_value=85, fix=0.3)}
+        label="demand_elec", inputs={bel: Flow(nominal_capacity=85, fix=0.3)}
     )
 
     demand_th = Sink(
-        label="demand_therm", inputs={bth: Flow(nominal_value=40, fix=0.2)}
+        label="demand_therm", inputs={bth: Flow(nominal_capacity=40, fix=0.2)}
     )
 
     # combined heat and power plant (chp)
@@ -57,8 +57,8 @@ def test_dispatch_one_time_step(solver="cbc"):
         label="pp_chp",
         inputs={bgas: Flow()},
         outputs={
-            bel: Flow(nominal_value=30, variable_costs=42),
-            bth: Flow(nominal_value=40),
+            bel: Flow(nominal_capacity=30, variable_costs=42),
+            bth: Flow(nominal_capacity=40),
         },
         conversion_factors={bel: 0.3, bth: 0.4},
     )
@@ -72,7 +72,7 @@ def test_dispatch_one_time_step(solver="cbc"):
     heat_pump = Converter(
         label="heat_pump",
         inputs={bel: Flow(), b_heat_source: Flow()},
-        outputs={bth: Flow(nominal_value=10)},
+        outputs={bth: Flow(nominal_capacity=10)},
         conversion_factors={bel: 1 / 3, b_heat_source: (cop - 1) / cop},
     )
 
diff --git a/tests/test_scripts/test_solph/test_simple_model/test_simple_dispatch_one_explicit_timemode.py b/tests/test_scripts/test_solph/test_simple_model/test_simple_dispatch_one_explicit_timemode.py
index 99a2f7478..2ba6aebbe 100644
--- a/tests/test_scripts/test_solph/test_simple_model/test_simple_dispatch_one_explicit_timemode.py
+++ b/tests/test_scripts/test_solph/test_simple_model/test_simple_dispatch_one_explicit_timemode.py
@@ -40,16 +40,16 @@ def test_dispatch_one_time_step(solver="cbc"):
 
     # sources
     wind = Source(
-        label="wind", outputs={bel: Flow(fix=0.5, nominal_value=66.3)}
+        label="wind", outputs={bel: Flow(fix=0.5, nominal_capacity=66.3)}
     )
 
     # demands (electricity/heat)
     demand_el = Sink(
-        label="demand_elec", inputs={bel: Flow(nominal_value=85, fix=0.3)}
+        label="demand_elec", inputs={bel: Flow(nominal_capacity=85, fix=0.3)}
     )
 
     demand_th = Sink(
-        label="demand_therm", inputs={bth: Flow(nominal_value=40, fix=0.2)}
+        label="demand_therm", inputs={bth: Flow(nominal_capacity=40, fix=0.2)}
     )
 
     # combined heat and power plant (chp)
@@ -57,8 +57,8 @@ def test_dispatch_one_time_step(solver="cbc"):
         label="pp_chp",
         inputs={bgas: Flow()},
         outputs={
-            bel: Flow(nominal_value=30, variable_costs=42),
-            bth: Flow(nominal_value=40),
+            bel: Flow(nominal_capacity=30, variable_costs=42),
+            bth: Flow(nominal_capacity=40),
         },
         conversion_factors={bel: 0.3, bth: 0.4},
     )
@@ -72,7 +72,7 @@ def test_dispatch_one_time_step(solver="cbc"):
     heat_pump = Converter(
         label="heat_pump",
         inputs={bel: Flow(), b_heat_source: Flow()},
-        outputs={bth: Flow(nominal_value=10)},
+        outputs={bth: Flow(nominal_capacity=10)},
         conversion_factors={bel: 1 / 3, b_heat_source: (cop - 1) / cop},
     )
 
diff --git a/tests/test_scripts/test_solph/test_simple_model/test_simple_invest.py b/tests/test_scripts/test_solph/test_simple_model/test_simple_invest.py
index 3634406f3..0d6e5d3b9 100644
--- a/tests/test_scripts/test_solph/test_simple_model/test_simple_invest.py
+++ b/tests/test_scripts/test_solph/test_simple_model/test_simple_invest.py
@@ -61,7 +61,7 @@ def test_dispatch_example(solver="cbc", periods=24 * 5):
         outputs={
             bel: Flow(
                 fix=data["wind"],
-                nominal_value=Investment(ep_costs=ep_wind, existing=100),
+                nominal_capacity=Investment(ep_costs=ep_wind, existing=100),
             )
         },
     )
@@ -72,7 +72,7 @@ def test_dispatch_example(solver="cbc", periods=24 * 5):
         outputs={
             bel: Flow(
                 fix=data["pv"],
-                nominal_value=Investment(ep_costs=ep_pv, existing=80),
+                nominal_capacity=Investment(ep_costs=ep_pv, existing=80),
             )
         },
     )
@@ -80,40 +80,40 @@ def test_dispatch_example(solver="cbc", periods=24 * 5):
     # demands (electricity/heat)
     demand_el = Sink(
         label="demand_elec",
-        inputs={bel: Flow(nominal_value=85, fix=data["demand_el"])},
+        inputs={bel: Flow(nominal_capacity=85, fix=data["demand_el"])},
     )
 
     demand_th = Sink(
         label="demand_therm",
-        inputs={bth: Flow(nominal_value=40, fix=data["demand_th"])},
+        inputs={bth: Flow(nominal_capacity=40, fix=data["demand_th"])},
     )
 
     # power plants
     pp_coal = Converter(
         label="pp_coal",
         inputs={bcoal: Flow()},
-        outputs={bel: Flow(nominal_value=20.2, variable_costs=25)},
+        outputs={bel: Flow(nominal_capacity=20.2, variable_costs=25)},
         conversion_factors={bel: 0.39},
     )
 
     pp_lig = Converter(
         label="pp_lig",
         inputs={blig: Flow()},
-        outputs={bel: Flow(nominal_value=11.8, variable_costs=19)},
+        outputs={bel: Flow(nominal_capacity=11.8, variable_costs=19)},
         conversion_factors={bel: 0.41},
     )
 
     pp_gas = Converter(
         label="pp_gas",
         inputs={bgas: Flow()},
-        outputs={bel: Flow(nominal_value=41, variable_costs=40)},
+        outputs={bel: Flow(nominal_capacity=41, variable_costs=40)},
         conversion_factors={bel: 0.50},
     )
 
     pp_oil = Converter(
         label="pp_oil",
         inputs={boil: Flow()},
-        outputs={bel: Flow(nominal_value=5, variable_costs=50)},
+        outputs={bel: Flow(nominal_capacity=5, variable_costs=50)},
         conversion_factors={bel: 0.28},
     )
 
@@ -122,8 +122,8 @@ def test_dispatch_example(solver="cbc", periods=24 * 5):
         label="pp_chp",
         inputs={bgas: Flow()},
         outputs={
-            bel: Flow(nominal_value=30, variable_costs=42),
-            bth: Flow(nominal_value=40),
+            bel: Flow(nominal_capacity=30, variable_costs=42),
+            bth: Flow(nominal_capacity=40),
         },
         conversion_factors={bel: 0.3, bth: 0.4},
     )
@@ -137,7 +137,7 @@ def test_dispatch_example(solver="cbc", periods=24 * 5):
     heat_pump = Converter(
         label="el_heat_pump",
         inputs={bel: Flow(), b_heat_source: Flow()},
-        outputs={bth: Flow(nominal_value=10)},
+        outputs={bth: Flow(nominal_capacity=10)},
         conversion_factors={bel: 1 / 3, b_heat_source: (cop - 1) / cop},
     )
 
diff --git a/tests/test_scripts/test_solph/test_storage_investment/test_invest_storage_regression.py b/tests/test_scripts/test_solph/test_storage_investment/test_invest_storage_regression.py
index b33f915e5..244556e1f 100644
--- a/tests/test_scripts/test_solph/test_storage_investment/test_invest_storage_regression.py
+++ b/tests/test_scripts/test_solph/test_storage_investment/test_invest_storage_regression.py
@@ -39,7 +39,7 @@ def test_regression_investment_storage(solver="cbc"):
             label="demand",
             inputs={
                 bel: solph.flows.Flow(
-                    fix=[209643, 207497, 200108, 191892], nominal_value=1
+                    fix=[209643, 207497, 200108, 191892], nominal_capacity=1
                 )
             },
         )
@@ -57,7 +57,7 @@ def test_regression_investment_storage(solver="cbc"):
         solph.components.Converter(
             label="pp_gas",
             inputs={bgas: solph.flows.Flow()},
-            outputs={bel: solph.flows.Flow(nominal_value=300000)},
+            outputs={bel: solph.flows.Flow(nominal_capacity=300000)},
             conversion_factors={bel: 0.58},
         )
     )
@@ -68,14 +68,14 @@ def test_regression_investment_storage(solver="cbc"):
             label="storage",
             inputs={
                 bel: solph.flows.Flow(
-                    nominal_value=solph.Investment(
+                    nominal_capacity=solph.Investment(
                         existing=625046 / 6, maximum=0
                     )
                 )
             },
             outputs={
                 bel: solph.flows.Flow(
-                    nominal_value=solph.Investment(
+                    nominal_capacity=solph.Investment(
                         existing=104174.33, maximum=1
                     )
                 )
diff --git a/tests/test_scripts/test_solph/test_storage_investment/test_storage_investment.py b/tests/test_scripts/test_solph/test_storage_investment/test_storage_investment.py
index 92232979b..478d7273d 100644
--- a/tests/test_scripts/test_solph/test_storage_investment/test_storage_investment.py
+++ b/tests/test_scripts/test_solph/test_storage_investment/test_storage_investment.py
@@ -80,7 +80,9 @@ def test_optimise_storage_size(
         solph.components.Sink(
             label="demand",
             inputs={
-                bel: solph.flows.Flow(fix=data["demand_el"], nominal_value=1)
+                bel: solph.flows.Flow(
+                    fix=data["demand_el"], nominal_capacity=1
+                )
             },
         )
     )
@@ -91,7 +93,8 @@ def test_optimise_storage_size(
             label="rgas",
             outputs={
                 bgas: solph.flows.Flow(
-                    nominal_value=194397000 * 400 / 8760, full_load_time_max=1
+                    nominal_capacity=194397000 * 400 / 8760,
+                    full_load_time_max=1,
                 )
             },
         )
@@ -101,7 +104,9 @@ def test_optimise_storage_size(
         solph.components.Source(
             label="wind",
             outputs={
-                bel: solph.flows.Flow(fix=data["wind"], nominal_value=1000000)
+                bel: solph.flows.Flow(
+                    fix=data["wind"], nominal_capacity=1000000
+                )
             },
         )
     )
@@ -110,7 +115,7 @@ def test_optimise_storage_size(
         solph.components.Source(
             label="pv",
             outputs={
-                bel: solph.flows.Flow(fix=data["pv"], nominal_value=582000)
+                bel: solph.flows.Flow(fix=data["pv"], nominal_capacity=582000)
             },
         )
     )
@@ -120,7 +125,7 @@ def test_optimise_storage_size(
         label="pp_gas",
         inputs={bgas: solph.flows.Flow()},
         outputs={
-            bel: solph.flows.Flow(nominal_value=10e10, variable_costs=50)
+            bel: solph.flows.Flow(nominal_capacity=10e10, variable_costs=50)
         },
         conversion_factors={bel: 0.58},
     )
diff --git a/tests/test_scripts/test_solph/test_storage_investment/test_storage_with_tuple_label.py b/tests/test_scripts/test_solph/test_storage_investment/test_storage_with_tuple_label.py
index 7dea33903..3027f02fe 100644
--- a/tests/test_scripts/test_solph/test_storage_investment/test_storage_with_tuple_label.py
+++ b/tests/test_scripts/test_solph/test_storage_investment/test_storage_with_tuple_label.py
@@ -90,7 +90,9 @@ def test_tuples_as_labels_example(
         solph.components.Sink(
             label=Label("sink", "electricity", "demand"),
             inputs={
-                bel: solph.flows.Flow(fix=data["demand_el"], nominal_value=1)
+                bel: solph.flows.Flow(
+                    fix=data["demand_el"], nominal_capacity=1
+                )
             },
         )
     )
@@ -101,7 +103,8 @@ def test_tuples_as_labels_example(
             label=Label("source", "natural_gas", "commodity"),
             outputs={
                 bgas: solph.flows.Flow(
-                    nominal_value=194397000 * 400 / 8760, full_load_time_max=1
+                    nominal_capacity=194397000 * 400 / 8760,
+                    full_load_time_max=1,
                 )
             },
         )
@@ -111,7 +114,9 @@ def test_tuples_as_labels_example(
         solph.components.Source(
             label=Label("renewable", "electricity", "wind"),
             outputs={
-                bel: solph.flows.Flow(fix=data["wind"], nominal_value=1000000)
+                bel: solph.flows.Flow(
+                    fix=data["wind"], nominal_capacity=1000000
+                )
             },
         )
     )
@@ -122,7 +127,7 @@ def test_tuples_as_labels_example(
             outputs={
                 bel: solph.flows.Flow(
                     fix=data["pv"],
-                    nominal_value=582000,
+                    nominal_capacity=582000,
                 )
             },
         )
@@ -134,7 +139,9 @@ def test_tuples_as_labels_example(
             label=Label("pp", "electricity", "natural_gas"),
             inputs={bgas: solph.flows.Flow()},
             outputs={
-                bel: solph.flows.Flow(nominal_value=10e10, variable_costs=50)
+                bel: solph.flows.Flow(
+                    nominal_capacity=10e10, variable_costs=50
+                )
             },
             conversion_factors={bel: 0.58},
         )
diff --git a/tests/test_scripts/test_solph/test_variable_chp/test_variable_chp.py b/tests/test_scripts/test_solph/test_variable_chp/test_variable_chp.py
index 4b790bd22..0f9f4c514 100644
--- a/tests/test_scripts/test_solph/test_variable_chp/test_variable_chp.py
+++ b/tests/test_scripts/test_solph/test_variable_chp/test_variable_chp.py
@@ -87,7 +87,9 @@ def test_variable_chp(filename="variable_chp.csv", solver="cbc"):
         solph.components.Sink(
             label=("demand", "elec1"),
             inputs={
-                bel: solph.flows.Flow(fix=data["demand_el"], nominal_value=1)
+                bel: solph.flows.Flow(
+                    fix=data["demand_el"], nominal_capacity=1
+                )
             },
         )
     )
@@ -95,7 +97,9 @@ def test_variable_chp(filename="variable_chp.csv", solver="cbc"):
         solph.components.Sink(
             label=("demand", "elec2"),
             inputs={
-                bel2: solph.flows.Flow(fix=data["demand_el"], nominal_value=1)
+                bel2: solph.flows.Flow(
+                    fix=data["demand_el"], nominal_capacity=1
+                )
             },
         )
     )
@@ -106,7 +110,7 @@ def test_variable_chp(filename="variable_chp.csv", solver="cbc"):
             label=("demand", "therm1"),
             inputs={
                 bth: solph.flows.Flow(
-                    fix=data["demand_th"], nominal_value=741000
+                    fix=data["demand_th"], nominal_capacity=741000
                 )
             },
         )
@@ -116,7 +120,7 @@ def test_variable_chp(filename="variable_chp.csv", solver="cbc"):
             label=("demand", "therm2"),
             inputs={
                 bth2: solph.flows.Flow(
-                    fix=data["demand_th"], nominal_value=741000
+                    fix=data["demand_th"], nominal_capacity=741000
                 )
             },
         )
@@ -126,7 +130,7 @@ def test_variable_chp(filename="variable_chp.csv", solver="cbc"):
     energysystem.add(
         solph.components.Converter(
             label=("fixed_chp", "gas"),
-            inputs={bgas: solph.flows.Flow(nominal_value=10e10)},
+            inputs={bgas: solph.flows.Flow(nominal_capacity=10e10)},
             outputs={bel2: solph.flows.Flow(), bth2: solph.flows.Flow()},
             conversion_factors={bel2: 0.3, bth2: 0.5},
         )
@@ -136,7 +140,7 @@ def test_variable_chp(filename="variable_chp.csv", solver="cbc"):
     energysystem.add(
         solph.components.ExtractionTurbineCHP(
             label=("variable_chp", "gas"),
-            inputs={bgas: solph.flows.Flow(nominal_value=10e10)},
+            inputs={bgas: solph.flows.Flow(nominal_capacity=10e10)},
             outputs={bel: solph.flows.Flow(), bth: solph.flows.Flow()},
             conversion_factors={bel: 0.3, bth: 0.5},
             conversion_factor_full_condensation={bel: 0.5},
diff --git a/tests/test_solph_network_classes.py b/tests/test_solph_network_classes.py
index 5edad18c9..5d3a11a50 100644
--- a/tests/test_solph_network_classes.py
+++ b/tests/test_solph_network_classes.py
@@ -160,7 +160,7 @@ def test_attributes_needing_nominal_value_get_it():
 def test_min_max_values_for_bidirectional_flow():
     a = solph.flows.Flow(bidirectional=True)  # use default values
     b = solph.flows.Flow(
-        bidirectional=True, nominal_value=1, min=-0.8, max=0.9
+        bidirectional=True, nominal_capacity=1, min=-0.8, max=0.9
     )
     assert a.bidirectional
     assert a.max[0] == 1
diff --git a/tests/test_warnings.py b/tests/test_warnings.py
index 6b66f961d..ef81c732e 100644
--- a/tests/test_warnings.py
+++ b/tests/test_warnings.py
@@ -94,7 +94,7 @@ def test_nonconvex_investment_without_maximum_raises_warning(warning_fixture):
             variable_costs=25,
             min=0.2,
             max=0.8,
-            nominal_value=solph.Investment(
+            nominal_capacity=solph.Investment(
                 ep_costs=500,  # no maximum is provided here
             ),
             nonconvex=solph.NonConvex(),
@@ -140,8 +140,8 @@ def test_link_raise_key_error_in_Linkblock(warning_fixture):
     link = solph.components.Link(
         label="transshipment_link",
         inputs={
-            bel0: solph.flows.Flow(nominal_value=4),
-            bel1: solph.flows.Flow(nominal_value=2),
+            bel0: solph.flows.Flow(nominal_capacity=4),
+            bel1: solph.flows.Flow(nominal_capacity=2),
         },
         outputs={bel0: solph.flows.Flow(), look_out: solph.flows.Flow()},
         conversion_factors={(bel0, bel1): 0.8, (bel1, bel0): 0.7},

From df65fe40da4e175f8ef05103cd1993946a66b4c2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrik=20Sch=C3=B6nfeldt?= <patrik@proxima.snft.de>
Date: Thu, 22 Aug 2024 14:17:05 +0200
Subject: [PATCH 05/10] Rename attribute Flow.nominal_value to nominal_capacity

---
 .../simple_time_step_example.py               |  2 +-
 src/oemof/solph/_models.py                    |  8 +-
 .../solph/components/_generic_storage.py      |  2 +-
 .../solph/components/_offset_converter.py     |  2 +-
 .../_piecewise_linear_converter.py            |  6 +-
 src/oemof/solph/constraints/storage_level.py  |  6 +-
 src/oemof/solph/flows/_flow.py                | 14 +--
 .../flows/_invest_non_convex_flow_block.py    |  2 +-
 .../solph/flows/_non_convex_flow_block.py     |  4 +-
 src/oemof/solph/flows/_simple_flow_block.py   | 20 ++---
 .../flows/experimental/_electrical_line.py    |  2 +-
 .../test_components/test_offset_converter.py  | 86 ++++++++++---------
 tests/test_flows/test_flow_class.py           |  2 +-
 tests/test_flows/test_simple_flow.py          |  8 +-
 tests/test_processing.py                      |  4 +-
 15 files changed, 87 insertions(+), 81 deletions(-)

diff --git a/examples/time_index_example/simple_time_step_example.py b/examples/time_index_example/simple_time_step_example.py
index 9d6cb5b07..868f8f93d 100644
--- a/examples/time_index_example/simple_time_step_example.py
+++ b/examples/time_index_example/simple_time_step_example.py
@@ -13,7 +13,7 @@
 * The initial_storage_level of a GenericStorage is given at the first time step.
   If the storage is balanced, this is the same storage level as in the last time
   step.
-* The nominal_value in Flows has to be interpreted in means of power: We have
+* The nominal_capacity in Flows has to be interpreted in means of power: We have
   nominal_capacity=0.5, but the maximum change of the storage content of an ideal
   storage is 0.125.
 
diff --git a/src/oemof/solph/_models.py b/src/oemof/solph/_models.py
index 5ecbbd474..74e49b69d 100644
--- a/src/oemof/solph/_models.py
+++ b/src/oemof/solph/_models.py
@@ -314,25 +314,25 @@ def _add_parent_block_variables(self):
         self.flow = po.Var(self.FLOWS, self.TIMESTEPS, within=po.Reals)
 
         for o, i in self.FLOWS:
-            if self.flows[o, i].nominal_value is not None:
+            if self.flows[o, i].nominal_capacity is not None:
                 if self.flows[o, i].fix[self.TIMESTEPS.at(1)] is not None:
                     for t in self.TIMESTEPS:
                         self.flow[o, i, t].value = (
                             self.flows[o, i].fix[t]
-                            * self.flows[o, i].nominal_value
+                            * self.flows[o, i].nominal_capacity
                         )
                         self.flow[o, i, t].fix()
                 else:
                     for t in self.TIMESTEPS:
                         self.flow[o, i, t].setub(
                             self.flows[o, i].max[t]
-                            * self.flows[o, i].nominal_value
+                            * self.flows[o, i].nominal_capacity
                         )
                     if not self.flows[o, i].nonconvex:
                         for t in self.TIMESTEPS:
                             self.flow[o, i, t].setlb(
                                 self.flows[o, i].min[t]
-                                * self.flows[o, i].nominal_value
+                                * self.flows[o, i].nominal_capacity
                             )
                     elif (o, i) in self.UNIDIRECTIONAL_FLOWS:
                         for t in self.TIMESTEPS:
diff --git a/src/oemof/solph/components/_generic_storage.py b/src/oemof/solph/components/_generic_storage.py
index f8fd76df7..eff79ae11 100644
--- a/src/oemof/solph/components/_generic_storage.py
+++ b/src/oemof/solph/components/_generic_storage.py
@@ -104,7 +104,7 @@ class GenericStorage(Node):
     max_storage_level : numeric (iterable or scalar), :math:`c_{max}(t)`
         see: min_storage_level
     investment : :class:`oemof.solph.options.Investment` object
-        Object indicating if a nominal_value of the flow is determined by
+        Object indicating if a nominal_capacity of the flow is determined by
         the optimization problem. Note: This will refer all attributes to an
         investment variable instead of to the nominal_storage_capacity. The
         nominal_storage_capacity should not be set (or set to None) if an
diff --git a/src/oemof/solph/components/_offset_converter.py b/src/oemof/solph/components/_offset_converter.py
index b33442f6c..25c51f95a 100644
--- a/src/oemof/solph/components/_offset_converter.py
+++ b/src/oemof/solph/components/_offset_converter.py
@@ -46,7 +46,7 @@ class OffsetConverter(Node):
     normed_offsets : dict, (:math:`y_\text{0,normed}(t)`)
         Dict containing the respective bus as key and as value the parameter
         :math:`y_\text{0,normed}(t)`. It represents the y-intercept with respect
-        to the `NonConvex` flow divided by the `nominal_value` of the
+        to the `NonConvex` flow divided by the `nominal_capacity` of the
         `NonConvex` flow (this is for internal purposes). The value can either
         be a scalar or a sequence with length of time horizon for simulation.
     Notes
diff --git a/src/oemof/solph/components/experimental/_piecewise_linear_converter.py b/src/oemof/solph/components/experimental/_piecewise_linear_converter.py
index ef2e5192b..2cd155d42 100644
--- a/src/oemof/solph/components/experimental/_piecewise_linear_converter.py
+++ b/src/oemof/solph/components/experimental/_piecewise_linear_converter.py
@@ -94,8 +94,10 @@ def __init__(
                 + "more than 1 input and 1 output!"
             )
 
-        nominal_value = [a.nominal_value for a in self.inputs.values()][0]
-        if max(self.in_breakpoints) < nominal_value:
+        nominal_capacity = [a.nominal_capacity for a in self.inputs.values()][
+            0
+        ]
+        if max(self.in_breakpoints) < nominal_capacity:
             raise ValueError(
                 "Largest in_breakpoint must be larger or equal "
                 + "nominal value"
diff --git a/src/oemof/solph/constraints/storage_level.py b/src/oemof/solph/constraints/storage_level.py
index 87c892bdf..60d538c10 100644
--- a/src/oemof/solph/constraints/storage_level.py
+++ b/src/oemof/solph/constraints/storage_level.py
@@ -24,7 +24,7 @@ def storage_level_constraint(
     As a GenericStorage just allows exactly one input and one output,
     an additional bus, the multiplexer_bus, is used for the connections.
     Note that all Flow objects connected to the multiplexer_bus have to have
-    a nominal_value.
+    a nominal_capacity.
 
     Parameters
     ----------
@@ -91,7 +91,7 @@ def _output_active_rule(m):
         def _constraint_output_rule(m, o, t):
             return (
                 m.flow[multiplexer_bus, o, t]
-                / m.flows[multiplexer_bus, o].nominal_value
+                / m.flows[multiplexer_bus, o].nominal_capacity
                 <= active_output[o, t]
             )
 
@@ -156,7 +156,7 @@ def _input_active_rule(m):
         def _constraint_input_rule(m, i, t):
             return (
                 m.flow[i, multiplexer_bus, t]
-                / m.flows[i, multiplexer_bus].nominal_value
+                / m.flows[i, multiplexer_bus].nominal_capacity
                 <= 1 - inactive_input[i, t]
             )
 
diff --git a/src/oemof/solph/flows/_flow.py b/src/oemof/solph/flows/_flow.py
index ded156642..6e2d859d8 100644
--- a/src/oemof/solph/flows/_flow.py
+++ b/src/oemof/solph/flows/_flow.py
@@ -53,12 +53,12 @@ class Flow(Edge):
         will be added to the objective expression of the optimization problem.
     max : numeric (iterable or scalar), :math:`f_{max}`
         Normed maximum value of the flow. The flow absolute maximum will be
-        calculated by multiplying :attr:`nominal_value` with :attr:`max`
+        calculated by multiplying :attr:`nominal_capacity` with :attr:`max`
     min : numeric (iterable or scalar), :math:`f_{min}`
         Normed minimum value of the flow (see :attr:`max`).
     fix : numeric (iterable or scalar), :math:`f_{fix}`
         Normed fixed value for the flow variable. Will be multiplied with the
-        :attr:`nominal_value` to get the absolute value.
+        :attr:`nominal_capacity` to get the absolute value.
     positive_gradient_limit : numeric (iterable, scalar or None)
         the normed *upper bound* on the positive difference
         (`flow[t-1] < flow[t]`) of two consecutive flow values.
@@ -206,7 +206,7 @@ def __init__(
             for attribute, value in custom_attributes.items():
                 setattr(self, attribute, value)
 
-        self.nominal_value = None
+        self.nominal_capacity = None
         self.investment = None
 
         infinite_error_msg = (
@@ -216,7 +216,7 @@ def __init__(
         if isinstance(nominal_capacity, numbers.Real):
             if not math.isfinite(nominal_capacity):
                 raise ValueError(infinite_error_msg.format("nominal_capacity"))
-            self.nominal_value = nominal_capacity
+            self.nominal_capacity = nominal_capacity
         elif isinstance(nominal_capacity, Investment):
             self.investment = nominal_capacity
 
@@ -260,7 +260,7 @@ def __init__(
             "max",
         ]
         sequences = ["fix", "variable_costs", "min", "max"]
-        if self.investment is None and self.nominal_value is None:
+        if self.investment is None and self.nominal_capacity is None:
             for attr in need_nominal_value:
                 if isinstance(eval(attr), Iterable):
                     the_attr = eval(attr)[0]
@@ -287,7 +287,9 @@ def __init__(
         for attr in sequences:
             setattr(self, attr, sequence(eval(attr)))
 
-        if self.nominal_value is not None and not math.isfinite(self.max[0]):
+        if self.nominal_capacity is not None and not math.isfinite(
+            self.max[0]
+        ):
             raise ValueError(infinite_error_msg.format("max"))
 
         # Checking for impossible gradient combinations
diff --git a/src/oemof/solph/flows/_invest_non_convex_flow_block.py b/src/oemof/solph/flows/_invest_non_convex_flow_block.py
index 747c17f79..84be801c8 100644
--- a/src/oemof/solph/flows/_invest_non_convex_flow_block.py
+++ b/src/oemof/solph/flows/_invest_non_convex_flow_block.py
@@ -121,7 +121,7 @@ def _investvar_bound_rule(block, i, o, p):
 
         # `status_nominal` is a parameter which represents the
         # multiplication of a binary variable (`status`)
-        # and a continuous variable (`invest` or `nominal_value`)
+        # and a continuous variable (`invest` or `nominal_capacity`)
         self.status_nominal = Var(
             self.INVEST_NON_CONVEX_FLOWS, m.TIMESTEPS, within=NonNegativeReals
         )
diff --git a/src/oemof/solph/flows/_non_convex_flow_block.py b/src/oemof/solph/flows/_non_convex_flow_block.py
index 88eb76850..3d2c1d9f2 100644
--- a/src/oemof/solph/flows/_non_convex_flow_block.py
+++ b/src/oemof/solph/flows/_non_convex_flow_block.py
@@ -97,7 +97,7 @@ def _create_variables(self):
 
         # `status_nominal` is a parameter which represents the
         # multiplication of a binary variable (`status`)
-        # and a continuous variable (`invest` or `nominal_value`)
+        # and a continuous variable (`invest` or `nominal_capacity`)
         self.status_nominal = Var(
             self.NONCONVEX_FLOWS, m.TIMESTEPS, within=NonNegativeReals
         )
@@ -648,7 +648,7 @@ def _status_nominal_rule(_, i, o, t):
             """Rule definition for status_nominal"""
             expr = (
                 self.status_nominal[i, o, t]
-                == self.status[i, o, t] * m.flows[i, o].nominal_value
+                == self.status[i, o, t] * m.flows[i, o].nominal_capacity
             )
             return expr
 
diff --git a/src/oemof/solph/flows/_simple_flow_block.py b/src/oemof/solph/flows/_simple_flow_block.py
index dc893592b..ad3b1caa1 100644
--- a/src/oemof/solph/flows/_simple_flow_block.py
+++ b/src/oemof/solph/flows/_simple_flow_block.py
@@ -75,7 +75,7 @@ def _create_sets(self, group):
                 (g[0], g[1])
                 for g in group
                 if g[2].full_load_time_max is not None
-                and g[2].nominal_value is not None
+                and g[2].nominal_capacity is not None
             ]
         )
 
@@ -84,7 +84,7 @@ def _create_sets(self, group):
                 (g[0], g[1])
                 for g in group
                 if g[2].full_load_time_min is not None
-                and g[2].nominal_value is not None
+                and g[2].nominal_capacity is not None
             ]
         )
 
@@ -175,12 +175,12 @@ def _create_variables(self, group):
             if m.flows[i, o].positive_gradient_limit[0] is not None:
                 for t in m.TIMESTEPS:
                     self.positive_gradient[i, o, t].setub(
-                        f.positive_gradient_limit[t] * f.nominal_value
+                        f.positive_gradient_limit[t] * f.nominal_capacity
                     )
             if m.flows[i, o].negative_gradient_limit[0] is not None:
                 for t in m.TIMESTEPS:
                     self.negative_gradient[i, o, t].setub(
-                        f.negative_gradient_limit[t] * f.nominal_value
+                        f.negative_gradient_limit[t] * f.nominal_capacity
                     )
 
     def _create_constraints(self):
@@ -220,7 +220,7 @@ def _flow_full_load_time_max_rule(model):
                 )
                 rhs = (
                     m.flows[inp, out].full_load_time_max
-                    * m.flows[inp, out].nominal_value
+                    * m.flows[inp, out].nominal_capacity
                 )
                 self.full_load_time_max_constr.add((inp, out), lhs <= rhs)
 
@@ -240,7 +240,7 @@ def _flow_full_load_time_min_rule(_):
                 )
                 rhs = (
                     m.flows[inp, out].full_load_time_min
-                    * m.flows[inp, out].nominal_value
+                    * m.flows[inp, out].nominal_capacity
                 )
                 self.full_load_time_min_constr.add((inp, out), lhs >= rhs)
 
@@ -451,12 +451,12 @@ def _objective_expression(self):
                 # Fixed costs for units with no lifetime limit
                 if (
                     m.flows[i, o].fixed_costs[0] is not None
-                    and m.flows[i, o].nominal_value is not None
+                    and m.flows[i, o].nominal_capacity is not None
                     and (i, o) not in self.LIFETIME_FLOWS
                     and (i, o) not in self.LIFETIME_AGE_FLOWS
                 ):
                     fixed_costs += sum(
-                        m.flows[i, o].nominal_value
+                        m.flows[i, o].nominal_capacity
                         * m.flows[i, o].fixed_costs[pp]
                         * ((1 + m.discount_rate) ** (-pp))
                         for pp in range(m.es.end_year_of_optimization)
@@ -470,7 +470,7 @@ def _objective_expression(self):
                         m.flows[i, o].lifetime,
                     )
                     fixed_costs += sum(
-                        m.flows[i, o].nominal_value
+                        m.flows[i, o].nominal_capacity
                         * m.flows[i, o].fixed_costs[pp]
                         * ((1 + m.discount_rate) ** (-pp))
                         for pp in range(range_limit)
@@ -483,7 +483,7 @@ def _objective_expression(self):
                         m.flows[i, o].lifetime - m.flows[i, o].age,
                     )
                     fixed_costs += sum(
-                        m.flows[i, o].nominal_value
+                        m.flows[i, o].nominal_capacity
                         * m.flows[i, o].fixed_costs[pp]
                         * ((1 + m.discount_rate) ** (-pp))
                         for pp in range(range_limit)
diff --git a/src/oemof/solph/flows/experimental/_electrical_line.py b/src/oemof/solph/flows/experimental/_electrical_line.py
index 8edd417f0..a3dd0e4cd 100644
--- a/src/oemof/solph/flows/experimental/_electrical_line.py
+++ b/src/oemof/solph/flows/experimental/_electrical_line.py
@@ -60,7 +60,7 @@ class ElectricalLine(Flow):
 
     def __init__(self, **kwargs):
         super().__init__(
-            nominal_capacity=kwargs.get("nominal_value"),
+            nominal_capacity=kwargs.get("nominal_capacity"),
             variable_costs=kwargs.get("variable_costs", 0),
             min=kwargs.get("min"),
             max=kwargs.get("max"),
diff --git a/tests/test_components/test_offset_converter.py b/tests/test_components/test_offset_converter.py
index c094cb5d0..82bdd9b59 100644
--- a/tests/test_components/test_offset_converter.py
+++ b/tests/test_components/test_offset_converter.py
@@ -53,7 +53,7 @@ def solve_and_extract_results(es):
 def check_results(
     results,
     reference_bus,
-    nominal_value,
+    nominal_capacity,
     minimal_value,
     eta_at_nom,
     eta_at_min,
@@ -62,7 +62,7 @@ def check_results(
         if "input" in reference_bus.label:
             slope, offset = slope_offset_from_nonconvex_input(
                 1,
-                minimal_value / nominal_value,
+                minimal_value / nominal_capacity,
                 eta_at_nom[bus],
                 eta_at_min[bus],
             )
@@ -75,7 +75,7 @@ def check_results(
         else:
             slope, offset = slope_offset_from_nonconvex_output(
                 1,
-                minimal_value / nominal_value,
+                minimal_value / nominal_capacity,
                 eta_at_nom[bus],
                 eta_at_min[bus],
             )
@@ -87,7 +87,7 @@ def check_results(
             ]["sequences"]["status"]
 
         flow_expected = (
-            offset * nominal_value * reference_flow_status
+            offset * nominal_capacity * reference_flow_status
             + slope * reference_flow
         )
         if "input" in bus.label:
@@ -103,7 +103,7 @@ def check_results(
 
 
 def add_OffsetConverter(
-    es, reference_bus, nominal_value, minimal_value, eta_at_nom, eta_at_min
+    es, reference_bus, nominal_capacity, minimal_value, eta_at_nom, eta_at_min
 ):
     # Use of experimental API to access nodes by label.
     # Can be removed with future release of network.
@@ -123,19 +123,21 @@ def add_OffsetConverter(
         if reference_bus in oc_outputs:
             f = oc_outputs[reference_bus]
             get_slope_and_offset = slope_offset_from_nonconvex_output
-            fix = [0] + np.linspace(minimal_value, nominal_value, 9).tolist()
+            fix = [0] + np.linspace(
+                minimal_value, nominal_capacity, 9
+            ).tolist()
         else:
             f = oc_inputs[reference_bus]
             get_slope_and_offset = slope_offset_from_nonconvex_input
             fix = [0] + np.linspace(
                 minimal_value * eta_at_min[es.node["bus output 0"]],
-                nominal_value * eta_at_nom[es.node["bus output 0"]],
+                nominal_capacity * eta_at_nom[es.node["bus output 0"]],
                 9,
             ).tolist()
 
         fix_flow = es.flows()[es.node["bus output 0"], es.node["sink 0"]]
         fix_flow.fix = fix
-        fix_flow.nominal_value = 1
+        fix_flow.nominal_capacity = 1
 
         slopes = {}
         offsets = {}
@@ -145,7 +147,7 @@ def add_OffsetConverter(
                 continue
             slope, offset = get_slope_and_offset(
                 1,
-                minimal_value / nominal_value,
+                minimal_value / nominal_capacity,
                 eta_at_nom[bus],
                 eta_at_min[bus],
             )
@@ -153,8 +155,8 @@ def add_OffsetConverter(
             offsets[bus] = offset
 
         f.nonconvex = solph.NonConvex()
-        f.nominal_value = nominal_value
-        f.min = sequence(minimal_value / nominal_value)
+        f.nominal_capacity = nominal_capacity
+        f.min = sequence(minimal_value / nominal_capacity)
 
         oc = solph.components.OffsetConverter(
             label="offset converter",
@@ -243,7 +245,7 @@ def test_OffsetConverter_single_input_output_ref_output():
     num_out = 1
     es = create_energysystem_stub(num_in, num_out)
 
-    nominal_value = 10
+    nominal_capacity = 10
     minimal_value = 3
 
     eta_at_nom = {es.groups["bus input 0"]: 0.7}
@@ -252,7 +254,7 @@ def test_OffsetConverter_single_input_output_ref_output():
     add_OffsetConverter(
         es,
         es.groups["bus output 0"],
-        nominal_value,
+        nominal_capacity,
         minimal_value,
         eta_at_nom,
         eta_at_min,
@@ -263,7 +265,7 @@ def test_OffsetConverter_single_input_output_ref_output():
     check_results(
         results,
         es.groups["bus output 0"],
-        nominal_value,
+        nominal_capacity,
         minimal_value,
         eta_at_nom,
         eta_at_min,
@@ -275,7 +277,7 @@ def test_OffsetConverter_single_input_output_ref_output_eta_decreasing():
     num_out = 1
     es = create_energysystem_stub(num_in, num_out)
 
-    nominal_value = 10
+    nominal_capacity = 10
     minimal_value = 3
 
     eta_at_nom = {es.groups["bus input 0"]: 0.5}
@@ -284,7 +286,7 @@ def test_OffsetConverter_single_input_output_ref_output_eta_decreasing():
     add_OffsetConverter(
         es,
         es.groups["bus output 0"],
-        nominal_value,
+        nominal_capacity,
         minimal_value,
         eta_at_nom,
         eta_at_min,
@@ -295,7 +297,7 @@ def test_OffsetConverter_single_input_output_ref_output_eta_decreasing():
     check_results(
         results,
         es.groups["bus output 0"],
-        nominal_value,
+        nominal_capacity,
         minimal_value,
         eta_at_nom,
         eta_at_min,
@@ -307,7 +309,7 @@ def test_OffsetConverter_single_input_output_ref_input():
     num_out = 1
     es = create_energysystem_stub(num_in, num_out)
 
-    nominal_value = 10
+    nominal_capacity = 10
     minimal_value = 3
 
     eta_at_nom = {es.groups["bus output 0"]: 0.7}
@@ -316,7 +318,7 @@ def test_OffsetConverter_single_input_output_ref_input():
     add_OffsetConverter(
         es,
         es.groups["bus input 0"],
-        nominal_value,
+        nominal_capacity,
         minimal_value,
         eta_at_nom,
         eta_at_min,
@@ -327,7 +329,7 @@ def test_OffsetConverter_single_input_output_ref_input():
     check_results(
         results,
         es.groups["bus input 0"],
-        nominal_value,
+        nominal_capacity,
         minimal_value,
         eta_at_nom,
         eta_at_min,
@@ -339,7 +341,7 @@ def test_OffsetConverter_single_input_output_ref_input_eta_decreasing():
     num_out = 1
     es = create_energysystem_stub(num_in, num_out)
 
-    nominal_value = 10
+    nominal_capacity = 10
     minimal_value = 3
 
     eta_at_nom = {es.groups["bus output 0"]: 0.5}
@@ -348,7 +350,7 @@ def test_OffsetConverter_single_input_output_ref_input_eta_decreasing():
     add_OffsetConverter(
         es,
         es.groups["bus input 0"],
-        nominal_value,
+        nominal_capacity,
         minimal_value,
         eta_at_nom,
         eta_at_min,
@@ -359,7 +361,7 @@ def test_OffsetConverter_single_input_output_ref_input_eta_decreasing():
     check_results(
         results,
         es.groups["bus input 0"],
-        nominal_value,
+        nominal_capacity,
         minimal_value,
         eta_at_nom,
         eta_at_min,
@@ -371,7 +373,7 @@ def test_OffsetConverter_double_input_output_ref_input():
     num_out = 2
     es = create_energysystem_stub(num_in, num_out)
 
-    nominal_value = 10
+    nominal_capacity = 10
     minimal_value = 3
 
     eta_at_nom = {
@@ -388,7 +390,7 @@ def test_OffsetConverter_double_input_output_ref_input():
     add_OffsetConverter(
         es,
         es.groups["bus input 0"],
-        nominal_value,
+        nominal_capacity,
         minimal_value,
         eta_at_nom,
         eta_at_min,
@@ -399,7 +401,7 @@ def test_OffsetConverter_double_input_output_ref_input():
     check_results(
         results,
         es.groups["bus input 0"],
-        nominal_value,
+        nominal_capacity,
         minimal_value,
         eta_at_nom,
         eta_at_min,
@@ -412,7 +414,7 @@ def test_OffsetConverter_double_input_output_ref_output():
 
     es = create_energysystem_stub(num_in, num_out)
 
-    nominal_value = 10
+    nominal_capacity = 10
     minimal_value = 3
 
     eta_at_nom = {
@@ -429,7 +431,7 @@ def test_OffsetConverter_double_input_output_ref_output():
     add_OffsetConverter(
         es,
         es.groups["bus output 0"],
-        nominal_value,
+        nominal_capacity,
         minimal_value,
         eta_at_nom,
         eta_at_min,
@@ -440,7 +442,7 @@ def test_OffsetConverter_double_input_output_ref_output():
     check_results(
         results,
         es.groups["bus output 0"],
-        nominal_value,
+        nominal_capacity,
         minimal_value,
         eta_at_nom,
         eta_at_min,
@@ -453,7 +455,7 @@ def test_two_OffsetConverters_with_and_without_investment():
 
     es = create_energysystem_stub(num_in, num_out)
 
-    nominal_value = 10
+    nominal_capacity = 10
     minimal_value = 3
 
     eta_at_nom = {
@@ -466,7 +468,7 @@ def test_two_OffsetConverters_with_and_without_investment():
     add_OffsetConverter(
         es,
         es.groups["bus output 0"],
-        nominal_value,
+        nominal_capacity,
         minimal_value,
         eta_at_nom,
         eta_at_min,
@@ -481,7 +483,7 @@ def test_two_OffsetConverters_with_and_without_investment():
             es.groups["bus output 0"]: solph.Flow(
                 nonconvex=solph.NonConvex(),
                 nominal_capacity=solph.Investment(
-                    maximum=nominal_value, ep_costs=10
+                    maximum=nominal_capacity, ep_costs=10
                 ),
             )
         },
@@ -507,25 +509,25 @@ def test_OffsetConverter_05x_compatibility():
     num_out = 1
     es = create_energysystem_stub(num_in, num_out)
 
-    nominal_value = 10
+    nominal_capacity = 10
     minimal_value = 3
 
     # Use of experimental API to access nodes by label.
     # Can be removed with future release of network.
     with warnings.catch_warnings():
         warnings.simplefilter("ignore", category=ExperimentalFeatureWarning)
-        fix = [0] + np.linspace(minimal_value, nominal_value, 9).tolist()
+        fix = [0] + np.linspace(minimal_value, nominal_capacity, 9).tolist()
         fix_flow = es.flows()[es.node["bus output 0"], es.node["sink 0"]]
         fix_flow.fix = fix
-        fix_flow.nominal_value = 1
+        fix_flow.nominal_capacity = 1
 
     eta_at_nom = 0.7
     eta_at_min = 0.5
 
-    slope = (nominal_value - minimal_value) / (
-        nominal_value / eta_at_nom - minimal_value / eta_at_min
+    slope = (nominal_capacity - minimal_value) / (
+        nominal_capacity / eta_at_nom - minimal_value / eta_at_min
     )
-    offset = minimal_value / nominal_value * (1 - slope / eta_at_min)
+    offset = minimal_value / nominal_capacity * (1 - slope / eta_at_min)
 
     warnings.filterwarnings("ignore", "", DeprecationWarning)
     oc = solph.components.OffsetConverter(
@@ -534,8 +536,8 @@ def test_OffsetConverter_05x_compatibility():
         outputs={
             es.groups["bus output 0"]: solph.Flow(
                 nonconvex=solph.NonConvex(),
-                nominal_capacity=nominal_value,
-                min=minimal_value / nominal_value,
+                nominal_capacity=nominal_capacity,
+                min=minimal_value / nominal_capacity,
             )
         },
         coefficients=(offset, slope),
@@ -547,7 +549,7 @@ def test_OffsetConverter_05x_compatibility():
     results = solve_and_extract_results(es)
 
     slope, offset = slope_offset_from_nonconvex_output(
-        1, minimal_value / nominal_value, 0.7, 0.5
+        1, minimal_value / nominal_capacity, 0.7, 0.5
     )
     output_flow = results["offset converter", "bus output 0"]["sequences"][
         "flow"
@@ -557,7 +559,7 @@ def test_OffsetConverter_05x_compatibility():
     ]["status"]
 
     input_flow_expected = (
-        offset * nominal_value * output_flow_status + slope * output_flow
+        offset * nominal_capacity * output_flow_status + slope * output_flow
     )
     input_flow_actual = results["bus input 0", "offset converter"][
         "sequences"
diff --git a/tests/test_flows/test_flow_class.py b/tests/test_flows/test_flow_class.py
index cf5805d23..5c3955c83 100644
--- a/tests/test_flows/test_flow_class.py
+++ b/tests/test_flows/test_flow_class.py
@@ -82,6 +82,6 @@ def test_fix_sequence():
 
 
 def test_fix_sequence_non_nominal():
-    """Attribute fix needs nominal_value"""
+    """Attribute fix needs nominal_capacity"""
     with pytest.raises(AttributeError):
         Flow(fix=[0.3, 0.2, 0.7])
diff --git a/tests/test_flows/test_simple_flow.py b/tests/test_flows/test_simple_flow.py
index 4bc0c4b36..e5c74ed91 100644
--- a/tests/test_flows/test_simple_flow.py
+++ b/tests/test_flows/test_simple_flow.py
@@ -58,13 +58,13 @@ def test_full_load_time_min():
 
 
 # --- BEGIN: The following code can be removed for versions >= v0.7 ---
-def test_nominal_value_warning():
-    with pytest.warns(FutureWarning, match="nominal_value"):
+def test_nominal_capacity_warning():
+    with pytest.warns(FutureWarning, match="nominal_capacity"):
         _ = solph.flows.Flow(nominal_value=2)
 
 
-def test_nominal_value_error():
-    with pytest.raises(AttributeError, match="nominal_value"):
+def test_nominal_capacity_error():
+    with pytest.raises(AttributeError, match="nominal_capacity"):
         _ = solph.flows.Flow(nominal_value=2, nominal_capacity=1)
 
 
diff --git a/tests/test_processing.py b/tests/test_processing.py
index e563fece7..0299ff627 100644
--- a/tests/test_processing.py
+++ b/tests/test_processing.py
@@ -99,7 +99,7 @@ def test_flows_with_none_exclusion(self):
                 {
                     "bidirectional": False,
                     "integer": False,
-                    "nominal_value": 1,
+                    "nominal_capacity": 1,
                     "max": 1,
                     "min": 0,
                     "variable_costs": 0,
@@ -124,7 +124,7 @@ def test_flows_without_none_exclusion(self):
             "lifetime": None,
             "integer": False,
             "investment": None,
-            "nominal_value": 1,
+            "nominal_capacity": 1,
             "nonconvex": None,
             "bidirectional": False,
             "full_load_time_max": None,

From a2bca51479e7557e90f21d800aed26ad4ac1de80 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrik=20Sch=C3=B6nfeldt?= <patrik@proxima.snft.de>
Date: Thu, 22 Aug 2024 14:33:03 +0200
Subject: [PATCH 06/10] Rename "value" to "capacity" in docstrings

---
 examples/electrical/transshipment.py            | 2 +-
 examples/excel_reader/dispatch.py               | 2 +-
 src/oemof/solph/components/_offset_converter.py | 4 ++--
 src/oemof/solph/flows/_investment_flow_block.py | 4 ++--
 tests/test_components.py                        | 4 ++--
 5 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/examples/electrical/transshipment.py b/examples/electrical/transshipment.py
index 3a1e181e4..513aabfed 100644
--- a/examples/electrical/transshipment.py
+++ b/examples/electrical/transshipment.py
@@ -77,7 +77,7 @@ def draw_graph(
     grph : networkxGraph
         A graph to draw.
     edge_labels : boolean
-        Use nominal values of flow as edge label
+        Use nominal capacities of flow as edge label
     node_color : dict or string
         Hex color code oder matplotlib color for each node. If string, all
         colors are the same.
diff --git a/examples/excel_reader/dispatch.py b/examples/excel_reader/dispatch.py
index efb534f24..8927d6e9b 100644
--- a/examples/excel_reader/dispatch.py
+++ b/examples/excel_reader/dispatch.py
@@ -301,7 +301,7 @@ def draw_graph(
     grph : networkxGraph
         A graph to draw.
     edge_labels : boolean
-        Use nominal values of flow as edge label
+        Use nominal capacities of flow as edge label
     node_color : dict or string
         Hex color code oder matplotlib color for each node. If string, all
         colors are the same.
diff --git a/src/oemof/solph/components/_offset_converter.py b/src/oemof/solph/components/_offset_converter.py
index 25c51f95a..74778673d 100644
--- a/src/oemof/solph/components/_offset_converter.py
+++ b/src/oemof/solph/components/_offset_converter.py
@@ -579,7 +579,7 @@ def slope_offset_from_nonconvex_input(
 
     With the input load being at 100 %, in this example, the efficiency should
     be 30 %. With the input load being at 50 %, it should be 40 %. We can
-    calcualte slope and the offset which is normed to the nominal value of
+    calcualte slope and the offset which is normed to the nominal capacity of
     the referenced flow (in this case the input flow) always.
 
     >>> slope, offset = solph.components.slope_offset_from_nonconvex_input(
@@ -656,7 +656,7 @@ def slope_offset_from_nonconvex_output(
 
     With the output load being at 100 %, in this example, the efficiency should
     be 80 %. With the input load being at 50 %, it should be 70 %. We can
-    calcualte slope and the offset, which is normed to the nominal value of
+    calcualte slope and the offset, which is normed to the nominal capacity of
     the referenced flow (in this case the output flow) always.
 
     >>> slope, offset = solph.components.slope_offset_from_nonconvex_output(
diff --git a/src/oemof/solph/flows/_investment_flow_block.py b/src/oemof/solph/flows/_investment_flow_block.py
index e77ec40b5..bad8c6b8d 100644
--- a/src/oemof/solph/flows/_investment_flow_block.py
+++ b/src/oemof/solph/flows/_investment_flow_block.py
@@ -185,12 +185,12 @@ def _create_variables(self, _):
 
             Value of the investment variable in period p,
             equal to what is being invested and equivalent resp. similar to
-            the nominal value of the flows after optimization.
+            the nominal capacity of the flows after optimization.
 
         * :math:`P_{total}(p)`
 
             Total installed capacity / energy in period p,
-            equivalent to the nominal value of the flows after optimization.
+            equivalent to the nominal capacity of the flows after optimization.
 
         * :math:`P_{old}(p)`
 
diff --git a/tests/test_components.py b/tests/test_components.py
index 02a7b1d1e..8618af937 100644
--- a/tests/test_components.py
+++ b/tests/test_components.py
@@ -43,7 +43,7 @@ def test_generic_storage_1():
 
 
 def test_generic_storage_2():
-    """Nominal value defined with investment model."""
+    """Nominal capacity defined with investment model."""
     bel = Bus()
     with pytest.raises(
         AttributeError,
@@ -65,7 +65,7 @@ def test_generic_storage_2():
 
 
 def test_generic_storage_3():
-    """Nominal value defined with investment model."""
+    """Nominal capacity defined with investment model."""
     bel = Bus()
     components.GenericStorage(
         label="storage4",

From 6973a31e3c0990197e212cecf94af74a83de988b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrik=20Sch=C3=B6nfeldt?= <patrik@proxima.snft.de>
Date: Thu, 22 Aug 2024 14:43:29 +0200
Subject: [PATCH 07/10] Rename nominal_storage_capacity to nominal_capacity

---
 .../solph/components/_generic_storage.py      | 27 +++++++++---
 tests/test_components/test_storage.py         | 41 +++++++++++++++----
 2 files changed, 54 insertions(+), 14 deletions(-)

diff --git a/src/oemof/solph/components/_generic_storage.py b/src/oemof/solph/components/_generic_storage.py
index eff79ae11..e0e178403 100644
--- a/src/oemof/solph/components/_generic_storage.py
+++ b/src/oemof/solph/components/_generic_storage.py
@@ -167,7 +167,8 @@ def __init__(
         label=None,
         inputs=None,
         outputs=None,
-        nominal_storage_capacity=None,
+        nominal_capacity=None,
+        nominal_storage_capacity=None,  # Can be removed for versions >= v0.7
         initial_storage_level=None,
         investment=None,
         invest_relation_input_output=None,
@@ -207,20 +208,34 @@ def __init__(
                 + " nominal_storage_capacity."
                 + " Both options cannot be set at the same time."
             )
-            if nominal_storage_capacity is not None:
+            if nominal_capacity is not None:
                 raise AttributeError(msg)
             else:
                 warn(msg, FutureWarning)
             nominal_storage_capacity = investment
         # --- END ---
+        # --- BEGIN: The following code can be removed for versions >= v0.6 ---
+        if nominal_storage_capacity is not None:
+            msg = (
+                "For backward compatibility,"
+                " the option nominal_storage_capacity overwrites the option"
+                + " nominal_capacity."
+                + " Both options cannot be set at the same time."
+            )
+            if nominal_capacity is not None:
+                raise AttributeError(msg)
+            else:
+                warn(msg, FutureWarning)
+            nominal_capacity = nominal_storage_capacity
+        # --- END ---
 
         self.nominal_storage_capacity = None
         self.investment = None
         self._invest_group = False
-        if isinstance(nominal_storage_capacity, numbers.Real):
-            self.nominal_storage_capacity = nominal_storage_capacity
-        elif isinstance(nominal_storage_capacity, Investment):
-            self.investment = nominal_storage_capacity
+        if isinstance(nominal_capacity, numbers.Real):
+            self.nominal_storage_capacity = nominal_capacity
+        elif isinstance(nominal_capacity, Investment):
+            self.investment = nominal_capacity
             self._invest_group = True
 
         self.initial_storage_level = initial_storage_level
diff --git a/tests/test_components/test_storage.py b/tests/test_components/test_storage.py
index 16faf3fae..ec6494456 100644
--- a/tests/test_components/test_storage.py
+++ b/tests/test_components/test_storage.py
@@ -28,7 +28,7 @@ def test_relative_losses():
             "storage",
             inputs={bus: solph.Flow(variable_costs=1)},
             outputs={bus: solph.Flow(variable_costs=1)},
-            nominal_storage_capacity=10,
+            nominal_capacity=10,
             initial_storage_level=1,
             loss_rate=0.004125876075,  # half life of one week
         )
@@ -76,7 +76,7 @@ def test_invest_power_uncoupled():
                 nominal_capacity=solph.Investment(ep_costs=0.1),
             )
         },
-        nominal_storage_capacity=10,
+        nominal_capacity=10,
         initial_storage_level=0,
         balanced=False,
     )
@@ -122,7 +122,7 @@ def test_invest_power_coupled():
                 nominal_capacity=solph.Investment(ep_costs=0.1),
             )
         },
-        nominal_storage_capacity=10,
+        nominal_capacity=10,
         invest_relation_input_output=0.5,
         initial_storage_level=0,
         balanced=False,
@@ -159,7 +159,7 @@ def test_storage_charging():
         "storage",
         inputs={bus: solph.Flow(nominal_capacity=2, variable_costs=-2)},
         outputs={bus: solph.Flow(nominal_capacity=0.1)},
-        nominal_storage_capacity=19,
+        nominal_capacity=19,
         initial_storage_level=0,
         balanced=False,
     )
@@ -194,7 +194,7 @@ def test_invest_content_uncoupled():
         "storage",
         inputs={bus: solph.Flow(nominal_capacity=2, variable_costs=-2)},
         outputs={bus: solph.Flow(nominal_capacity=0.1)},
-        nominal_storage_capacity=solph.Investment(
+        nominal_capacity=solph.Investment(
             ep_costs=0.1,
         ),
         initial_storage_level=0,
@@ -234,7 +234,7 @@ def test_invest_content_minimum():
         "storage",
         inputs={bus: solph.Flow(nominal_capacity=2, variable_costs=-2)},
         outputs={bus: solph.Flow(nominal_capacity=0.1, variable_costs=0.1)},
-        nominal_storage_capacity=solph.Investment(
+        nominal_capacity=solph.Investment(
             ep_costs=0.1,
             minimum=32,
         ),
@@ -275,7 +275,7 @@ def test_invest_content_minimum_nonconvex():
         "storage",
         inputs={bus: solph.Flow(nominal_capacity=2, variable_costs=0.1)},
         outputs={bus: solph.Flow(nominal_capacity=0.1, variable_costs=0.1)},
-        nominal_storage_capacity=solph.Investment(
+        nominal_capacity=solph.Investment(
             ep_costs=0.1,
             minimum=32,
             nonconvex=solph.NonConvex(),
@@ -321,7 +321,7 @@ def test_invest_content_maximum():
             )
         },
         outputs={bus: solph.Flow(nominal_capacity=0.1, variable_costs=0.1)},
-        nominal_storage_capacity=solph.Investment(
+        nominal_capacity=solph.Investment(
             ep_costs=0.1,
             maximum=10,
         ),
@@ -344,3 +344,28 @@ def test_invest_content_maximum():
     assert storage_content == pytest.approx(
         [min(i * 1.9, 10) for i in range(0, 11)]
     )
+
+
+# --- BEGIN: The following code can be removed for versions >= v0.6 ---
+def test_capacity_keyword_wrapper_warning():
+    with pytest.warns(FutureWarning, match="nominal_storage_capacity"):
+        bus = solph.Bus()
+        _ = solph.components.GenericStorage(
+            nominal_storage_capacity=5,
+            inputs={bus: solph.Flow()},
+            outputs={bus: solph.Flow()},
+        )
+
+
+def test_capacity_keyword_wrapper_error():
+    with pytest.raises(AttributeError, match="nominal_storage_capacity"):
+        bus = solph.Bus()
+        _ = solph.components.GenericStorage(
+            nominal_storage_capacity=5,
+            nominal_capacity=5,
+            inputs={bus: solph.Flow()},
+            outputs={bus: solph.Flow()},
+        )
+
+
+# --- END ---

From 96ab6f847f12068560fa22b6ca9a8448e8176d58 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrik=20Sch=C3=B6nfeldt?= <patrik@proxima.snft.de>
Date: Thu, 22 Aug 2024 14:49:19 +0200
Subject: [PATCH 08/10] Rename GenericStorage keyword to nominal_capacity

This way, it is analogue to teh keyword of the Flow.
---
 docs/usage.rst                                   |  4 ++--
 examples/basic_example/basic_example.py          |  2 +-
 .../dual_variable_example.py                     |  2 +-
 examples/excel_reader/dispatch.py                |  2 +-
 .../flexible_modelling/saturating_storage.py     |  2 +-
 examples/gradient_example/gradient_example.py    |  2 +-
 .../diesel_genset_nonconvex_investment.py        |  2 +-
 .../offset_diesel_genset_nonconvex_investment.py |  2 +-
 examples/storage_balanced_unbalanced/storage.py  |  2 +-
 examples/storage_costs/storage_costs.py          |  4 ++--
 .../v1_invest_optimize_all_technologies.py       |  2 +-
 .../v2_invest_optimize_only_gas_and_storage.py   |  2 +-
 ...st_optimize_only_storage_with_fossil_share.py |  2 +-
 ...ptimize_all_technologies_with_fossil_share.py |  2 +-
 .../storage_level_constraint.py                  |  2 +-
 .../non_equidistant_time_step_example.py         |  4 ++--
 .../simple_time_step_example.py                  |  2 +-
 examples/tuple_as_labels/tuple_as_label.py       |  2 +-
 src/oemof/solph/components/_generic_storage.py   |  4 ++--
 src/oemof/solph/constraints/shared_limit.py      |  4 ++--
 tests/test_components.py                         | 16 +++++++---------
 tests/test_constraints/test_storage_level.py     |  2 +-
 tests/test_non_equidistant_time_index.py         |  2 +-
 tests/test_processing.py                         |  2 +-
 .../test_connect_invest/test_connect_invest.py   |  2 +-
 .../test_multi_period_dispatch_model.py          |  2 +-
 .../test_multi_period_investment_model.py        |  2 +-
 .../test_invest_storage_regression.py            |  2 +-
 .../test_storage_investment.py                   |  2 +-
 .../test_storage_with_tuple_label.py             |  2 +-
 30 files changed, 41 insertions(+), 43 deletions(-)

diff --git a/docs/usage.rst b/docs/usage.rst
index a51fb2d66..9dbbbec2c 100644
--- a/docs/usage.rst
+++ b/docs/usage.rst
@@ -568,7 +568,7 @@ Furthermore, an efficiency for loading, unloading and a loss rate can be defined
         label='storage',
         inputs={b_el: solph.flows.Flow(nominal_capacity=9, variable_costs=10)},
         outputs={b_el: solph.flows.Flow(nominal_capacity=25, variable_costs=10)},
-        loss_rate=0.001, nominal_storage_capacity=50,
+        loss_rate=0.001, nominal_capacity=50,
         inflow_conversion_factor=0.98, outflow_conversion_factor=0.8)
 
 For initialising the state of charge before the first time step (time step zero) the parameter ``initial_storage_level`` (default value: ``None``) can be set by a numeric value as fraction of the storage capacity.
@@ -590,7 +590,7 @@ The following code block shows an example of the storage parametrization for the
         label='storage',
         inputs={b_el: solph.flows.Flow(nominal_capacity=9, variable_costs=10)},
         outputs={b_el: solph.flows.Flow(nominal_capacity=25, variable_costs=10)},
-        loss_rate=0.001, nominal_storage_capacity=50,
+        loss_rate=0.001, nominal_capacity=50,
         initial_storage_level=0.5, balanced=True,
         inflow_conversion_factor=0.98, outflow_conversion_factor=0.8)
 
diff --git a/examples/basic_example/basic_example.py b/examples/basic_example/basic_example.py
index cfd8e32f5..2afd5a4e2 100644
--- a/examples/basic_example/basic_example.py
+++ b/examples/basic_example/basic_example.py
@@ -223,7 +223,7 @@ def main(dump_and_restore=False):
     nominal_capacity = nominal_capacity / 6
 
     battery_storage = components.GenericStorage(
-        nominal_storage_capacity=nominal_capacity,
+        nominal_capacity=nominal_capacity,
         label=STORAGE_LABEL,
         inputs={
             bus_electricity: flows.Flow(nominal_capacity=nominal_capacity)
diff --git a/examples/dual_variable_example/dual_variable_example.py b/examples/dual_variable_example/dual_variable_example.py
index 0e26c2472..a06f792d6 100644
--- a/examples/dual_variable_example/dual_variable_example.py
+++ b/examples/dual_variable_example/dual_variable_example.py
@@ -223,7 +223,7 @@ def main():
     # create storage object representing a battery
     cap = 400
     storage = cmp.GenericStorage(
-        nominal_storage_capacity=cap,
+        nominal_capacity=cap,
         label="storage",
         inputs={bus_elec: flows.Flow(nominal_capacity=cap / 6)},
         outputs={
diff --git a/examples/excel_reader/dispatch.py b/examples/excel_reader/dispatch.py
index 8927d6e9b..baa099a99 100644
--- a/examples/excel_reader/dispatch.py
+++ b/examples/excel_reader/dispatch.py
@@ -250,7 +250,7 @@ def create_nodes(nd=None):
                             variable_costs=s["variable output costs"],
                         )
                     },
-                    nominal_storage_capacity=s["nominal capacity"],
+                    nominal_capacity=s["nominal capacity"],
                     loss_rate=s["capacity loss"],
                     initial_storage_level=s["initial capacity"],
                     max_storage_level=s["capacity max"],
diff --git a/examples/flexible_modelling/saturating_storage.py b/examples/flexible_modelling/saturating_storage.py
index 757e685bb..342a6733f 100644
--- a/examples/flexible_modelling/saturating_storage.py
+++ b/examples/flexible_modelling/saturating_storage.py
@@ -73,7 +73,7 @@ def saturating_storage_example():
     storage_capacity = 10
     battery = solph.components.GenericStorage(
         label="battery",
-        nominal_storage_capacity=storage_capacity,
+        nominal_capacity=storage_capacity,
         inputs={bel: solph.Flow(nominal_capacity=inflow_capacity)},
         outputs={bel: solph.Flow(variable_costs=2)},
         initial_storage_level=0,
diff --git a/examples/gradient_example/gradient_example.py b/examples/gradient_example/gradient_example.py
index b50269a1a..166b85e62 100644
--- a/examples/gradient_example/gradient_example.py
+++ b/examples/gradient_example/gradient_example.py
@@ -153,7 +153,7 @@ def main():
 
     # create storage object representing a battery
     storage = cmp.GenericStorage(
-        nominal_storage_capacity=999999999,
+        nominal_capacity=999999999,
         label="storage",
         inputs={bel: flows.Flow()},
         outputs={bel: flows.Flow()},
diff --git a/examples/invest_nonconvex_flow_examples/diesel_genset_nonconvex_investment.py b/examples/invest_nonconvex_flow_examples/diesel_genset_nonconvex_investment.py
index 60f12b7e9..f400c3619 100644
--- a/examples/invest_nonconvex_flow_examples/diesel_genset_nonconvex_investment.py
+++ b/examples/invest_nonconvex_flow_examples/diesel_genset_nonconvex_investment.py
@@ -209,7 +209,7 @@ def main():
     epc_battery = 101.00  # currency/kWh/year
     battery = solph.components.GenericStorage(
         label="battery",
-        nominal_storage_capacity=solph.Investment(
+        nominal_capacity=solph.Investment(
             ep_costs=epc_battery * n_days / n_days_in_year
         ),
         inputs={b_el_dc: solph.flows.Flow(variable_costs=0)},
diff --git a/examples/offset_converter_example/offset_diesel_genset_nonconvex_investment.py b/examples/offset_converter_example/offset_diesel_genset_nonconvex_investment.py
index 3bea2bcae..841a6b8a1 100644
--- a/examples/offset_converter_example/offset_diesel_genset_nonconvex_investment.py
+++ b/examples/offset_converter_example/offset_diesel_genset_nonconvex_investment.py
@@ -224,7 +224,7 @@ def offset_converter_example():
     epc_battery = 101.00  # currency/kWh/year
     battery = solph.components.GenericStorage(
         label="battery",
-        nominal_storage_capacity=solph.Investment(
+        nominal_capacity=solph.Investment(
             ep_costs=epc_battery * n_days / n_days_in_year
         ),
         inputs={b_el_dc: solph.flows.Flow(variable_costs=0)},
diff --git a/examples/storage_balanced_unbalanced/storage.py b/examples/storage_balanced_unbalanced/storage.py
index d26e8419e..23aa73a5d 100644
--- a/examples/storage_balanced_unbalanced/storage.py
+++ b/examples/storage_balanced_unbalanced/storage.py
@@ -118,7 +118,7 @@ def storage_example():
         es.add(
             solph.components.GenericStorage(
                 label="storage_elec_{0}".format(name),
-                nominal_storage_capacity=PARAMETER["nominal_storage_capacity"],
+                nominal_capacity=PARAMETER["nominal_storage_capacity"],
                 inputs={bel: solph.Flow()},
                 outputs={bel: solph.Flow()},
                 initial_storage_level=data_set["initial_storage_level"],
diff --git a/examples/storage_costs/storage_costs.py b/examples/storage_costs/storage_costs.py
index 39bfae556..90ce6a03a 100644
--- a/examples/storage_costs/storage_costs.py
+++ b/examples/storage_costs/storage_costs.py
@@ -86,7 +86,7 @@ def storage_costs_example():
     # last four time steps but emptying it is not a good option.
     battery1 = solph.components.GenericStorage(
         label="battery 1",
-        nominal_storage_capacity=10,
+        nominal_capacity=10,
         inputs={
             bel: solph.Flow(
                 nominal_capacity=1,
@@ -108,7 +108,7 @@ def storage_costs_example():
     # Electric Storage 2
     battery2 = solph.components.GenericStorage(
         label="battery 2",
-        nominal_storage_capacity=10,
+        nominal_capacity=10,
         inputs={
             bel: solph.Flow(
                 nominal_capacity=1,
diff --git a/examples/storage_investment/v1_invest_optimize_all_technologies.py b/examples/storage_investment/v1_invest_optimize_all_technologies.py
index 45c5a1d25..6a3d74fa9 100644
--- a/examples/storage_investment/v1_invest_optimize_all_technologies.py
+++ b/examples/storage_investment/v1_invest_optimize_all_technologies.py
@@ -192,7 +192,7 @@ def main():
         invest_relation_output_capacity=1 / 6,
         inflow_conversion_factor=1,
         outflow_conversion_factor=0.8,
-        nominal_storage_capacity=solph.Investment(ep_costs=epc_storage),
+        nominal_capacity=solph.Investment(ep_costs=epc_storage),
     )
 
     energysystem.add(excess, gas_resource, wind, pv, demand, pp_gas, storage)
diff --git a/examples/storage_investment/v2_invest_optimize_only_gas_and_storage.py b/examples/storage_investment/v2_invest_optimize_only_gas_and_storage.py
index 528059e03..863410bb3 100644
--- a/examples/storage_investment/v2_invest_optimize_only_gas_and_storage.py
+++ b/examples/storage_investment/v2_invest_optimize_only_gas_and_storage.py
@@ -184,7 +184,7 @@ def main():
         invest_relation_output_capacity=1 / 6,
         inflow_conversion_factor=1,
         outflow_conversion_factor=0.8,
-        nominal_storage_capacity=solph.Investment(ep_costs=epc_storage),
+        nominal_capacity=solph.Investment(ep_costs=epc_storage),
     )
 
     energysystem.add(excess, gas_resource, wind, pv, demand, pp_gas, storage)
diff --git a/examples/storage_investment/v3_invest_optimize_only_storage_with_fossil_share.py b/examples/storage_investment/v3_invest_optimize_only_storage_with_fossil_share.py
index 4c254e2be..15a420c26 100644
--- a/examples/storage_investment/v3_invest_optimize_only_storage_with_fossil_share.py
+++ b/examples/storage_investment/v3_invest_optimize_only_storage_with_fossil_share.py
@@ -194,7 +194,7 @@ def main():
         invest_relation_output_capacity=1 / 6,
         inflow_conversion_factor=1,
         outflow_conversion_factor=0.8,
-        nominal_storage_capacity=solph.Investment(ep_costs=epc_storage),
+        nominal_capacity=solph.Investment(ep_costs=epc_storage),
     )
 
     energysystem.add(excess, gas_resource, wind, pv, demand, pp_gas, storage)
diff --git a/examples/storage_investment/v4_invest_optimize_all_technologies_with_fossil_share.py b/examples/storage_investment/v4_invest_optimize_all_technologies_with_fossil_share.py
index 2e9264ff1..d8cfc49c4 100644
--- a/examples/storage_investment/v4_invest_optimize_all_technologies_with_fossil_share.py
+++ b/examples/storage_investment/v4_invest_optimize_all_technologies_with_fossil_share.py
@@ -203,7 +203,7 @@ def main():
         invest_relation_output_capacity=1 / 6,
         inflow_conversion_factor=1,
         outflow_conversion_factor=0.8,
-        nominal_storage_capacity=solph.Investment(ep_costs=epc_storage),
+        nominal_capacity=solph.Investment(ep_costs=epc_storage),
     )
 
     energysystem.add(excess, gas_resource, wind, pv, demand, pp_gas, storage)
diff --git a/examples/storage_level_constraint/storage_level_constraint.py b/examples/storage_level_constraint/storage_level_constraint.py
index cbc237445..247ef9dc0 100644
--- a/examples/storage_level_constraint/storage_level_constraint.py
+++ b/examples/storage_level_constraint/storage_level_constraint.py
@@ -61,7 +61,7 @@ def storage_level_constraint_example():
 
     storage = GenericStorage(
         label="storage",
-        nominal_storage_capacity=3,
+        nominal_capacity=3,
         initial_storage_level=1,
         balanced=True,
         loss_rate=0.05,
diff --git a/examples/time_index_example/non_equidistant_time_step_example.py b/examples/time_index_example/non_equidistant_time_step_example.py
index 02c91af34..33f40fb3d 100644
--- a/examples/time_index_example/non_equidistant_time_step_example.py
+++ b/examples/time_index_example/non_equidistant_time_step_example.py
@@ -87,7 +87,7 @@ def main():
         label="storage_fixed",
         inputs={bus: solph.flows.Flow()},
         outputs={bus: solph.flows.Flow()},
-        nominal_storage_capacity=8,
+        nominal_capacity=8,
         initial_storage_level=1,
         fixed_losses_absolute=1,  # 1 energy unit loss per hour
     )
@@ -102,7 +102,7 @@ def main():
                 nominal_capacity=4, max=[0, 0, 0, 0, 0, 0, 0, 1, 1]
             )
         },
-        nominal_storage_capacity=8,
+        nominal_capacity=8,
         initial_storage_level=1,
         loss_rate=0.5,  # 50 % losses per hour
     )
diff --git a/examples/time_index_example/simple_time_step_example.py b/examples/time_index_example/simple_time_step_example.py
index 868f8f93d..4ff1957eb 100644
--- a/examples/time_index_example/simple_time_step_example.py
+++ b/examples/time_index_example/simple_time_step_example.py
@@ -70,7 +70,7 @@ def main():
         label="storage",
         inputs={bus: solph.flows.Flow()},
         outputs={bus: solph.flows.Flow()},
-        nominal_storage_capacity=4,
+        nominal_capacity=4,
         initial_storage_level=0.5,
     )
     sink = solph.components.Sink(
diff --git a/examples/tuple_as_labels/tuple_as_label.py b/examples/tuple_as_labels/tuple_as_label.py
index 50c904851..f8fea8b4e 100644
--- a/examples/tuple_as_labels/tuple_as_label.py
+++ b/examples/tuple_as_labels/tuple_as_label.py
@@ -237,7 +237,7 @@ def main():
     # create storage object representing a battery
     nominal_storage_capacity = 5000
     storage = comp.GenericStorage(
-        nominal_storage_capacity=nominal_storage_capacity,
+        nominal_capacity=nominal_storage_capacity,
         label=Label("storage", "electricity", "battery"),
         inputs={
             bel: flows.Flow(nominal_capacity=nominal_storage_capacity / 6)
diff --git a/src/oemof/solph/components/_generic_storage.py b/src/oemof/solph/components/_generic_storage.py
index e0e178403..a976114b0 100644
--- a/src/oemof/solph/components/_generic_storage.py
+++ b/src/oemof/solph/components/_generic_storage.py
@@ -140,7 +140,7 @@ class GenericStorage(Node):
 
     >>> my_storage = solph.components.GenericStorage(
     ...     label='storage',
-    ...     nominal_storage_capacity=1000,
+    ...     nominal_capacity=1000,
     ...     inputs={my_bus: solph.flows.Flow(nominal_capacity=200, variable_costs=10)},
     ...     outputs={my_bus: solph.flows.Flow(nominal_capacity=200)},
     ...     loss_rate=0.01,
@@ -151,7 +151,7 @@ class GenericStorage(Node):
 
     >>> my_investment_storage = solph.components.GenericStorage(
     ...     label='storage',
-    ...     nominal_storage_capacity=solph.Investment(ep_costs=50),
+    ...     nominal_capacity=solph.Investment(ep_costs=50),
     ...     inputs={my_bus: solph.flows.Flow()},
     ...     outputs={my_bus: solph.flows.Flow()},
     ...     loss_rate=0.02,
diff --git a/src/oemof/solph/constraints/shared_limit.py b/src/oemof/solph/constraints/shared_limit.py
index 3ab92b965..70a51bbbb 100644
--- a/src/oemof/solph/constraints/shared_limit.py
+++ b/src/oemof/solph/constraints/shared_limit.py
@@ -69,13 +69,13 @@ def shared_limit(
     >>> b2 = solph.buses.Bus(label="Party2Bus")
     >>> storage1 = solph.components.GenericStorage(
     ...     label="Party1Storage",
-    ...     nominal_storage_capacity=5,
+    ...     nominal_capacity=5,
     ...     inputs={b1: solph.flows.Flow()},
     ...     outputs={b1: solph.flows.Flow()}
     ... )
     >>> storage2 = solph.components.GenericStorage(
     ...     label="Party2Storage",
-    ...     nominal_storage_capacity=5,
+    ...     nominal_capacity=5,
     ...     inputs={b1: solph.flows.Flow()},
     ...     outputs={b1: solph.flows.Flow()}
     ... )
diff --git a/tests/test_components.py b/tests/test_components.py
index 8618af937..0dbc2d993 100644
--- a/tests/test_components.py
+++ b/tests/test_components.py
@@ -36,7 +36,7 @@ def test_generic_storage_1():
             invest_relation_input_output=1,
             invest_relation_output_capacity=1,
             invest_relation_input_capacity=1,
-            nominal_storage_capacity=Investment(),
+            nominal_capacity=Investment(),
             inflow_conversion_factor=1,
             outflow_conversion_factor=0.8,
         )
@@ -51,7 +51,7 @@ def test_generic_storage_2():
     ):
         components.GenericStorage(
             label="storage3",
-            nominal_storage_capacity=45,
+            nominal_capacity=45,
             inputs={bel: Flow(variable_costs=10e10)},
             outputs={bel: Flow(variable_costs=10e10)},
             loss_rate=0.00,
@@ -69,7 +69,7 @@ def test_generic_storage_3():
     bel = Bus()
     components.GenericStorage(
         label="storage4",
-        nominal_storage_capacity=45,
+        nominal_capacity=45,
         inputs={bel: Flow(nominal_capacity=23, variable_costs=10e10)},
         outputs={bel: Flow(nominal_capacity=7.5, variable_costs=10e10)},
         loss_rate=0.00,
@@ -87,7 +87,7 @@ def test_generic_storage_4():
     ):
         components.GenericStorage(
             label="storage4",
-            nominal_storage_capacity=10,
+            nominal_capacity=10,
             inputs={bel: Flow(variable_costs=10e10)},
             outputs={bel: Flow(variable_costs=10e10)},
             loss_rate=0.00,
@@ -130,7 +130,7 @@ def test_generic_storage_with_non_convex_invest_maximum():
             outputs={bel: Flow()},
             invest_relation_input_capacity=1 / 6,
             invest_relation_output_capacity=1 / 6,
-            nominal_storage_capacity=Investment(nonconvex=True),
+            nominal_capacity=Investment(nonconvex=True),
         )
 
 
@@ -146,7 +146,7 @@ def test_generic_storage_with_convex_invest_offset():
             outputs={bel: Flow()},
             invest_relation_input_capacity=1 / 6,
             invest_relation_output_capacity=1 / 6,
-            nominal_storage_capacity=Investment(offset=10),
+            nominal_capacity=Investment(offset=10),
         )
 
 
@@ -177,9 +177,7 @@ def test_generic_storage_with_invest_and_fixed_losses_absolute():
             label="storage4",
             inputs={bel: Flow()},
             outputs={bel: Flow()},
-            nominal_storage_capacity=Investment(
-                ep_costs=23, minimum=0, existing=0
-            ),
+            nominal_capacity=Investment(ep_costs=23, minimum=0, existing=0),
             fixed_losses_absolute=[0, 0, 4],
         )
 
diff --git a/tests/test_constraints/test_storage_level.py b/tests/test_constraints/test_storage_level.py
index e55f7a7ed..6c066e162 100644
--- a/tests/test_constraints/test_storage_level.py
+++ b/tests/test_constraints/test_storage_level.py
@@ -19,7 +19,7 @@ def test_storage_level_constraint():
 
     storage = solph.components.GenericStorage(
         label="storage",
-        nominal_storage_capacity=3,
+        nominal_capacity=3,
         initial_storage_level=1,
         balanced=True,
         storage_costs=0.1,
diff --git a/tests/test_non_equidistant_time_index.py b/tests/test_non_equidistant_time_index.py
index 24aed8d14..ee6534ed0 100644
--- a/tests/test_non_equidistant_time_index.py
+++ b/tests/test_non_equidistant_time_index.py
@@ -48,7 +48,7 @@ def setup_class(cls):
 
         batt = cmp.GenericStorage(
             label="storage",
-            nominal_storage_capacity=1000,
+            nominal_capacity=1000,
             inputs={b_el1: flows.Flow(variable_costs=3)},
             outputs={b_el1: flows.Flow(variable_costs=2.5)},
             loss_rate=0.00,
diff --git a/tests/test_processing.py b/tests/test_processing.py
index 0299ff627..15b09c096 100644
--- a/tests/test_processing.py
+++ b/tests/test_processing.py
@@ -67,7 +67,7 @@ def setup_class(cls):
             invest_relation_output_capacity=1 / 6,
             inflow_conversion_factor=1,
             outflow_conversion_factor=0.8,
-            nominal_storage_capacity=Investment(ep_costs=0.4),
+            nominal_capacity=Investment(ep_costs=0.4),
         )
 
         cls.demand_values = [0.0] + [100] * 23
diff --git a/tests/test_scripts/test_solph/test_connect_invest/test_connect_invest.py b/tests/test_scripts/test_solph/test_connect_invest/test_connect_invest.py
index 7af2cab04..c518cf402 100644
--- a/tests/test_scripts/test_solph/test_connect_invest/test_connect_invest.py
+++ b/tests/test_scripts/test_solph/test_connect_invest/test_connect_invest.py
@@ -79,7 +79,7 @@ def test_connect_invest():
         invest_relation_output_capacity=1 / 6,
         inflow_conversion_factor=1,
         outflow_conversion_factor=0.8,
-        nominal_storage_capacity=Investment(ep_costs=0.2),
+        nominal_capacity=Investment(ep_costs=0.2),
     )
     es.add(storage)
 
diff --git a/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_dispatch_model.py b/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_dispatch_model.py
index 3e391938a..83f7a5834 100644
--- a/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_dispatch_model.py
+++ b/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_dispatch_model.py
@@ -185,7 +185,7 @@ def test_multi_period_dispatch_model(solver="cbc"):
         outputs={
             bus_el: flows.Flow(nominal_capacity=20, variable_costs=0, max=1)
         },
-        nominal_storage_capacity=20,
+        nominal_capacity=20,
         loss_rate=0,
         initial_storage_level=0,
         max_storage_level=1,
diff --git a/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_investment_model.py b/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_investment_model.py
index fcaf31c93..047afd9e9 100644
--- a/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_investment_model.py
+++ b/tests/test_scripts/test_solph/test_multi_period_model/test_multi_period_investment_model.py
@@ -265,7 +265,7 @@ def test_multi_period_investment_model(solver="cbc"):
             invest_relation_input_capacity=None,
             invest_relation_output_capacity=None,
             fixed_costs=10,
-            nominal_storage_capacity=_options.Investment(
+            nominal_capacity=_options.Investment(
                 maximum=20,
                 ep_costs=1000,
                 existing=10,
diff --git a/tests/test_scripts/test_solph/test_storage_investment/test_invest_storage_regression.py b/tests/test_scripts/test_solph/test_storage_investment/test_invest_storage_regression.py
index 244556e1f..79d388791 100644
--- a/tests/test_scripts/test_solph/test_storage_investment/test_invest_storage_regression.py
+++ b/tests/test_scripts/test_solph/test_storage_investment/test_invest_storage_regression.py
@@ -86,7 +86,7 @@ def test_regression_investment_storage(solver="cbc"):
             invest_relation_output_capacity=1 / 6,
             inflow_conversion_factor=1,
             outflow_conversion_factor=0.8,
-            nominal_storage_capacity=solph.Investment(
+            nominal_capacity=solph.Investment(
                 ep_costs=50,
                 existing=625046,
             ),
diff --git a/tests/test_scripts/test_solph/test_storage_investment/test_storage_investment.py b/tests/test_scripts/test_solph/test_storage_investment/test_storage_investment.py
index 478d7273d..e64ee1fe4 100644
--- a/tests/test_scripts/test_solph/test_storage_investment/test_storage_investment.py
+++ b/tests/test_scripts/test_solph/test_storage_investment/test_storage_investment.py
@@ -144,7 +144,7 @@ def test_optimise_storage_size(
             invest_relation_output_capacity=1 / 6,
             inflow_conversion_factor=1,
             outflow_conversion_factor=0.8,
-            nominal_storage_capacity=solph.Investment(
+            nominal_capacity=solph.Investment(
                 ep_costs=epc,
                 existing=6851,
             ),
diff --git a/tests/test_scripts/test_solph/test_storage_investment/test_storage_with_tuple_label.py b/tests/test_scripts/test_solph/test_storage_investment/test_storage_with_tuple_label.py
index 3027f02fe..e907b9177 100644
--- a/tests/test_scripts/test_solph/test_storage_investment/test_storage_with_tuple_label.py
+++ b/tests/test_scripts/test_solph/test_storage_investment/test_storage_with_tuple_label.py
@@ -151,7 +151,7 @@ def test_tuples_as_labels_example(
     energysystem.add(
         solph.components.GenericStorage(
             label=Label("storage", "electricity", "battery"),
-            nominal_storage_capacity=204685,
+            nominal_capacity=204685,
             inputs={bel: solph.flows.Flow(variable_costs=10e10)},
             outputs={bel: solph.flows.Flow(variable_costs=10e10)},
             loss_rate=0.00,

From 822d8a783f21ca81d826ff1275723e49f301e7c0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrik=20Sch=C3=B6nfeldt?= <patrik@salacia.snft.de>
Date: Thu, 22 Aug 2024 15:35:13 +0200
Subject: [PATCH 09/10] Remove unneccesary code

---
 src/oemof/solph/flows/_flow.py | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/src/oemof/solph/flows/_flow.py b/src/oemof/solph/flows/_flow.py
index 6e2d859d8..30f0dd61e 100644
--- a/src/oemof/solph/flows/_flow.py
+++ b/src/oemof/solph/flows/_flow.py
@@ -192,12 +192,6 @@ def __init__(
             else:
                 warn(msg, FutureWarning)
             nominal_capacity = nominal_value
-
-        msg = (
-            "\nThe parameter '{0}' is deprecated and will be removed "
-            + "in version v0.6.\nUse the parameter '{1}', "
-            + "to avoid this warning and future problems. "
-        )
         # --- END ---
 
         super().__init__()

From 6909370fe9be4f992b784f1ff54d03bdf846fa38 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrik=20Sch=C3=B6nfeldt?= <patrik@salacia.snft.de>
Date: Thu, 22 Aug 2024 16:06:40 +0200
Subject: [PATCH 10/10] Properly name nominal_capacity in docstring

---
 src/oemof/solph/components/_generic_storage.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/oemof/solph/components/_generic_storage.py b/src/oemof/solph/components/_generic_storage.py
index a976114b0..43bd06946 100644
--- a/src/oemof/solph/components/_generic_storage.py
+++ b/src/oemof/solph/components/_generic_storage.py
@@ -49,7 +49,7 @@ class GenericStorage(Node):
 
     Parameters
     ----------
-    nominal_storage_capacity : numeric, :math:`E_{nom}` or
+    nominal_capacity : numeric, :math:`E_{nom}` or
             :class:`oemof.solph.options.Investment` object
         Absolute nominal capacity of the storage, fixed value or
         object describing parameter of investment optimisations.