diff --git a/src/oemof/network/energy_system.py b/src/oemof/network/energy_system.py
index 995a6de..ce45c83 100644
--- a/src/oemof/network/energy_system.py
+++ b/src/oemof/network/energy_system.py
@@ -17,6 +17,7 @@
 
 import logging
 import os
+import warnings
 from collections import deque
 
 import blinker
@@ -134,24 +135,41 @@ class EnergySystem:
     .. _blinker: https://blinker.readthedocs.io/en/stable/
     """
 
-    def __init__(self, **kwargs):
+    def __init__(
+        self,
+        *,
+        groupings=None,
+        results=None,
+        timeindex=None,
+        timeincrement=None,
+        temporal=None,
+        nodes=None,
+        entities=None,
+    ):
+        if groupings is None:
+            groupings = []
+        if entities is not None:
+            warnings.warn(
+                "Parameter 'entities' is deprecated, use 'nodes'"
+                + " instead. Will overwrite nodes.",
+                FutureWarning,
+            )
+            nodes = entities
+        if nodes is None:
+            nodes = []
+
         self._first_ungrouped_node_index_ = 0
         self._groups = {}
         self._groupings = [BY_UID] + [
-            g if isinstance(g, Grouping) else Entities(g)
-            for g in kwargs.get("groupings", [])
+            g if isinstance(g, Grouping) else Entities(g) for g in groupings
         ]
         self._nodes = {}
 
-        self.results = kwargs.get("results")
-
-        self.timeindex = kwargs.get("timeindex")
-
-        self.timeincrement = kwargs.get("timeincrement", None)
-
-        self.temporal = kwargs.get("temporal")
-
-        self.add(*kwargs.get("entities", ()))
+        self.results = results
+        self.timeindex = timeindex
+        self.timeincrement = timeincrement
+        self.temporal = temporal
+        self.add(*nodes)
 
     def add(self, *nodes):
         """Add :class:`nodes <oemof.network.Node>` to this energy system."""
diff --git a/src/oemof/network/graph.py b/src/oemof/network/graph.py
index e6708fc..d8b7024 100644
--- a/src/oemof/network/graph.py
+++ b/src/oemof/network/graph.py
@@ -52,14 +52,13 @@ def create_nx_graph(
     >>> import oemof.network.graph as grph
     >>> datetimeindex = pd.date_range('1/1/2017', periods=3, freq='H')
     >>> es = EnergySystem(timeindex=datetimeindex)
-    >>> b_gas = Bus(label='b_gas', balanced=False)
+    >>> b_gas = Bus(label='b_gas')
     >>> bel1 = Bus(label='bel1')
     >>> bel2 = Bus(label='bel2')
     >>> demand_el = Sink(label='demand_el', inputs = [bel1])
     >>> pp_gas = Transformer(label=('pp', 'gas'),
     ...                      inputs=[b_gas],
-    ...                      outputs=[bel1],
-    ...                      conversion_factors={bel1: 0.5})
+    ...                      outputs=[bel1])
     >>> line_to2 = Transformer(label='line_to2', inputs=[bel1], outputs=[bel2])
     >>> line_from2 = Transformer(label='line_from2',
     ...                          inputs=[bel2], outputs=[bel1])
diff --git a/src/oemof/network/groupings.py b/src/oemof/network/groupings.py
index 976e3e5..014d465 100644
--- a/src/oemof/network/groupings.py
+++ b/src/oemof/network/groupings.py
@@ -122,7 +122,7 @@ def __init__(self, key=None, constant_key=None, filter=None, **kwargs):
                 + "one of `key` or `constant_key`."
             )
         self.filter = filter
-        for kw in ["value", "merge", "filter"]:
+        for kw in ["value", "merge"]:
             if kw in kwargs:
                 setattr(self, kw, kwargs[kw])
 
diff --git a/src/oemof/network/network/edge.py b/src/oemof/network/network/edge.py
index 15c977c..9274d16 100644
--- a/src/oemof/network/network/edge.py
+++ b/src/oemof/network/network/edge.py
@@ -17,8 +17,6 @@
 
 from .entity import Entity
 
-EdgeLabel = namedtuple("EdgeLabel", ["input", "output"])
-
 
 class Edge(Entity):
     """
@@ -41,7 +39,7 @@ class Edge(Entity):
     name.
     """
 
-    Label = EdgeLabel
+    Label = namedtuple("EdgeLabel", ["input", "output"])
 
     def __init__(
         self,
@@ -49,7 +47,8 @@ def __init__(
         output_node=None,
         flow=None,
         values=None,
-        **kwargs,
+        *,
+        custom_properties=None,
     ):
         if flow is not None and values is not None:
             raise ValueError(
@@ -60,7 +59,10 @@ def __init__(
                 f"    `values`: {values}\n"
                 "Choose one."
             )
-        super().__init__(label=Edge.Label(input_node, output_node))
+        super().__init__(
+            label=Edge.Label(input_node, output_node),
+            custom_properties=custom_properties,
+        )
         self.values = values if values is not None else flow
         if input_node is not None and output_node is not None:
             input_node.outputs[output_node] = self
diff --git a/src/oemof/network/network/entity.py b/src/oemof/network/network/entity.py
index b63f476..63f83da 100644
--- a/src/oemof/network/network/entity.py
+++ b/src/oemof/network/network/entity.py
@@ -44,7 +44,7 @@ class Entity:
         to easily attach custom information to any Entity.
     """
 
-    def __init__(self, label=None, *, custom_properties=None, **kwargs):
+    def __init__(self, label=None, *, custom_properties=None):
         self._label = label
         if custom_properties is None:
             custom_properties = {}
@@ -76,11 +76,14 @@ def label(self):
         attribute holds the actual object passed as a parameter. Otherwise
         `node.label` is a synonym for `str(node)`.
         """
-        return (
-            self._label
-            if self._label is not None
-            else "<{} #0x{:x}>".format(type(self).__name__, id(self))
-        )
+        try:
+            return self._label if self._label is not None else self._id_label
+        except AttributeError:
+            return hash(self._id_label)
+
+    @property
+    def _id_label(self):
+        return "<{} #0x{:x}>".format(type(self).__name__, id(self))
 
     @label.setter
     def label(self, label):
diff --git a/src/oemof/network/network/nodes.py b/src/oemof/network/network/nodes.py
index 947e250..964c4f5 100644
--- a/src/oemof/network/network/nodes.py
+++ b/src/oemof/network/network/nodes.py
@@ -42,31 +42,43 @@ class Node(Entity):
         A dictionary mapping output nodes to corresponding outflows.
     """
 
-    def __init__(self, *args, **kwargs):
-        super().__init__(*args, **kwargs)
+    def __init__(
+        self,
+        label=None,
+        *,
+        inputs=None,
+        outputs=None,
+        custom_properties=None,
+    ):
+        super().__init__(label=label, custom_properties=custom_properties)
 
         self._inputs = Inputs(self)
         self._outputs = Outputs(self)
         self._in_edges = set()
 
+        if inputs is None:
+            inputs = {}
+        if outputs is None:
+            outputs = {}
+
         msg = "{} {!r} of {!r} not an instance of Node but of {}."
 
-        for i in kwargs.get("inputs", {}):
+        for i in inputs:
             if not isinstance(i, Node):
                 raise ValueError(msg.format("Input", i, self, type(i)))
             self._in_edges.add(i)
             try:
-                flow = kwargs["inputs"].get(i)
+                flow = inputs.get(i)
             except AttributeError:
                 flow = None
             edge = Edge.from_object(flow)
             edge.input = i
             edge.output = self
-        for o in kwargs.get("outputs", {}):
+        for o in outputs:
             if not isinstance(o, Node):
                 raise ValueError(msg.format("Output", o, self, type(o)))
             try:
-                flow = kwargs["outputs"].get(o)
+                flow = outputs.get(o)
             except AttributeError:
                 flow = None
             edge = Edge.from_object(flow)
diff --git a/tests/test_energy_system.py b/tests/test_energy_system.py
index 6e602f5..6a5f533 100644
--- a/tests/test_energy_system.py
+++ b/tests/test_energy_system.py
@@ -13,11 +13,23 @@
 SPDX-License-Identifier: MIT
 """
 
+import pytest
+
 from oemof.network import energy_system as es
 from oemof.network.network import Edge
 from oemof.network.network.nodes import Node
 
 
+def test_ensys_init():
+    node = Node("label")
+    ensys = es.EnergySystem(nodes=[node])
+    assert node in ensys.nodes
+
+    with pytest.warns(FutureWarning):
+        ensys = es.EnergySystem(entities=[node])
+        assert node in ensys.nodes
+
+
 class TestsEnergySystem:
     def setup_method(self):
         self.es = es.EnergySystem()
diff --git a/tests/test_groupings/test_groupings_basic.py b/tests/test_groupings/test_groupings_basic.py
index c509530..064ff6d 100644
--- a/tests/test_groupings/test_groupings_basic.py
+++ b/tests/test_groupings/test_groupings_basic.py
@@ -24,7 +24,7 @@
 
 def test_entity_grouping_on_construction():
     bus = Bus(label="test bus")
-    ensys = es.EnergySystem(entities=[bus])
+    ensys = es.EnergySystem(nodes=[bus])
     assert ensys.groups[bus.label] is bus
 
 
@@ -37,8 +37,8 @@ def by_uid(n):
 
     ensys = es.EnergySystem(groupings=[by_uid])
 
-    ungrouped = [Node(uid="Not in 'Group': {}".format(i)) for i in range(10)]
-    grouped = [Node(uid="In 'Group': {}".format(i)) for i in range(10)]
+    ungrouped = [Node(label="Not in 'Group': {}".format(i)) for i in range(10)]
+    grouped = [Node(label="In 'Group': {}".format(i)) for i in range(10)]
     assert None not in ensys.groups
     for g in ensys.groups.values():
         for e in ungrouped: