diff --git a/egret/common/lazy_ptdf_utils.py b/egret/common/lazy_ptdf_utils.py
index db3c9edf..7dfe4d75 100644
--- a/egret/common/lazy_ptdf_utils.py
+++ b/egret/common/lazy_ptdf_utils.py
@@ -697,7 +697,7 @@ def _add_contingency_violations(lazy_violations, flows, mb, md, solver, ptdf_opt
         contingencies_monitored.append((cn, i_b))
         if new_slacks:
             m = model
-            obj_coef = pyo.value(m.TimePeriodLengthHours*m.SystemContingencyLimitPenalty)
+            obj_coef = m.TimePeriodLengthHours*m.SystemContingencyLimitPenalty
 
             if persistent_solver:
                 m_model = m.model()
diff --git a/egret/model_library/unit_commitment/services.py b/egret/model_library/unit_commitment/services.py
index d9c88010..b69b5b8a 100644
--- a/egret/model_library/unit_commitment/services.py
+++ b/egret/model_library/unit_commitment/services.py
@@ -275,23 +275,28 @@ def _check_for_requirement( requirement ):
     default_reg_pen = value(model.LoadMismatchPenalty+model.ReserveShortfallPenalty)/2.
     ## set these penalties in relation to each other, from higher quality service to lower
     model.RegulationPenalty = Param(within=NonNegativeReals,
-                                    initialize=system.get('regulation_penalty_price', default_reg_pen))
+            initialize=system.get('regulation_penalty_price', default_reg_pen),
+            mutable=True)
 
     default_spin_pen = value(model.RegulationPenalty+model.ReserveShortfallPenalty)/2.
     model.SpinningReservePenalty = Param(within=NonNegativeReals, 
-                                         initialize=system.get('spinning_reserve_penalty_price', default_spin_pen))
+            initialize=system.get('spinning_reserve_penalty_price', default_spin_pen),
+            mutable=True)
 
     default_nspin_pen = value(model.SpinningReservePenalty+model.ReserveShortfallPenalty)/2.
     model.NonSpinningReservePenalty = Param(within=NonNegativeReals,
-                                            initialize=system.get('non_spinning_reserve_penalty_price', default_nspin_pen))
+            initialize=system.get('non_spinning_reserve_penalty_price', default_nspin_pen),
+            mutable=True)
 
     default_supp_pen = value(model.NonSpinningReservePenalty+model.ReserveShortfallPenalty)/2.
     model.SupplementalReservePenalty = Param(within=NonNegativeReals,
-                                             initialize=system.get('supplemental_reserve_penalty_price', default_supp_pen))
+            initialize=system.get('supplemental_reserve_penalty_price', default_supp_pen),
+            mutable=True)
 
     default_flex_pen = value(model.NonSpinningReservePenalty+model.SpinningReservePenalty)/2.
     model.FlexRampPenalty = Param(within=NonNegativeReals,
-                                  initialize=system.get('flexible_ramp_penalty_price', default_flex_pen))
+            initialize=system.get('flexible_ramp_penalty_price', default_flex_pen),
+            mutable=True)
 
     thermal_gen_attrs = md.attributes(element_type='generator', generator_type='thermal')