diff --git a/.gitignore b/.gitignore
index c71709a..0cf3b1f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,4 +2,5 @@
 /docs/_build/
 /docs/_build/doctrees/
 /docs/_build/html/
-/.idea/
\ No newline at end of file
+/.idea/
+/inputs/
\ No newline at end of file
diff --git a/src/B_read_from_files.py b/src/B_read_from_files.py
index 07496dd..ed6419b 100644
--- a/src/B_read_from_files.py
+++ b/src/B_read_from_files.py
@@ -59,6 +59,7 @@
     ELECTRICITY_MG_FOLDER,
     STORAGE_FOLDER,
     LP_FILES_FOLDER,
+    USE_BIDIRECTIONAL_INVERTER_CONSTRAINT,
 )
 
 # requires xlrd
@@ -414,6 +415,12 @@ def get_case_definitions(file, sheet_project_sites):
                 f"Parameter {EVALUATION_PERSPECTIVE} has to be either {AC_SYSTEM} or {DC_SYSTEM}, but is {case_definitions[case][EVALUATION_PERSPECTIVE]}"
             )
 
+        if USE_BIDIRECTIONAL_INVERTER_CONSTRAINT not in case_definitions[case]:
+            case_definitions[case][USE_BIDIRECTIONAL_INVERTER_CONSTRAINT] = False
+            logging.error(
+                f"Parameter {USE_BIDIRECTIONAL_INVERTER_CONSTRAINT} was not defined in excel input sheet and thus set to False."
+            )
+
         case_definitions[case].update(
             {
                 NUMBER_OF_EQUAL_GENERATORS: int(
diff --git a/src/C_sensitivity_experiments.py b/src/C_sensitivity_experiments.py
index a6fc14a..7a76a01 100644
--- a/src/C_sensitivity_experiments.py
+++ b/src/C_sensitivity_experiments.py
@@ -49,6 +49,7 @@
     INVERTER_DC_AC_COST_VAR,
     INVERTER_DC_AC_EFFICIENCY,
     INVERTER_DC_AC_LIFETIME,
+    INVERTER_RECTIFIER_CAPACITY_RATIO_FACTOR,
     MAINGRID_DISTANCE,
     MAINGRID_ELECTRICITY_PRICE,
     MAINGRID_EXTENSION_COST_INVESTMENT,
@@ -1112,6 +1113,7 @@ def test_techno_economical_parameters_complete(experiment):
         INVERTER_DC_AC_COST_VAR: 0,
         INVERTER_DC_AC_EFFICIENCY: 1,
         INVERTER_DC_AC_LIFETIME: 15,
+        INVERTER_RECTIFIER_CAPACITY_RATIO_FACTOR: 1,
         MAINGRID_DISTANCE: 0,
         MAINGRID_ELECTRICITY_PRICE: 0.15,
         MAINGRID_EXTENSION_COST_INVESTMENT: 0,
diff --git a/src/F_case_definitions.py b/src/F_case_definitions.py
index 71d9e32..68c8e1d 100644
--- a/src/F_case_definitions.py
+++ b/src/F_case_definitions.py
@@ -70,6 +70,7 @@
     SHARE_USAGE,
     SHARE_HYBRID,
     DEFAULT,
+    USE_BIDIRECTIONAL_INVERTER_CONSTRAINT,
 )
 
 # This is not really a necessary class, as the whole experiement could be given to the function, but it ensures, that
@@ -278,6 +279,13 @@ def update_dict(capacities_oem, specific_case, experiment):
     experiment_case_dict[ENABLE_INVERTER_ONLY_AT_BLACKOUT] = specific_case[
         ENABLE_INVERTER_ONLY_AT_BLACKOUT
     ]
+    
+    #################################################
+    # Include use bidirectional inverter constraint #
+    #################################################
+
+    experiment_case_dict[USE_BIDIRECTIONAL_INVERTER_CONSTRAINT] = specific_case[USE_BIDIRECTIONAL_INVERTER_CONSTRAINT]
+
     return experiment_case_dict
 
 
diff --git a/src/G1_oemof_create_model.py b/src/G1_oemof_create_model.py
index 684ae8c..522000d 100644
--- a/src/G1_oemof_create_model.py
+++ b/src/G1_oemof_create_model.py
@@ -25,7 +25,11 @@
     STORAGE_FIXED_CAPACITY,
     STORAGE_FIXED_POWER,
     RECTIFIER_AC_DC_FIXED_CAPACITY,
+    RECTIFIER_AC_DC_COST_INVESTMENT,
     INVERTER_DC_AC_FIXED_CAPACITY,
+    INVERTER_DC_AC_COST_INVESTMENT,
+    INVERTER_RECTIFIER_CAPACITY_RATIO_FACTOR,
+    USE_BIDIRECTIONAL_INVERTER_CONSTRAINT,
     ALLOW_SHORTAGE,
     STABILITY_CONSTRAINT,
     SHARE_BACKUP,
@@ -220,9 +224,9 @@ def build(experiment, case_dict):
     # ------------point of coupling (feedin)------------#
     if case_dict[PCC_FEEDIN_FIXED_CAPACITY] == None:
         pass
-        # pointofcoupling_feedin = None
+        pointofcoupling_feedin = None
     elif case_dict[PCC_FEEDIN_FIXED_CAPACITY] is False:
-        generate.pointofcoupling_feedin_oem(
+        pointofcoupling_feedin = generate.pointofcoupling_feedin_oem(
             micro_grid_system,
             bus_electricity_ac,
             bus_electricity_ng_feedin,
@@ -231,7 +235,7 @@ def build(experiment, case_dict):
         )
 
     elif isinstance(case_dict[PCC_FEEDIN_FIXED_CAPACITY], float):
-        generate.pointofcoupling_feedin_fix(
+        pointofcoupling_feedin = generate.pointofcoupling_feedin_fix(
             micro_grid_system,
             bus_electricity_ac,
             bus_electricity_ng_feedin,
@@ -452,6 +456,45 @@ def build(experiment, case_dict):
             + " faulty at renewable_share_constraint. Value can only be True or False"
         )
 
+    # ------------Link transformer station capacities constraint ------------#
+    if case_dict[PCC_CONSUMPTION_FIXED_CAPACITY] != None and case_dict[PCC_FEEDIN_FIXED_CAPACITY] != None:
+        logging.info("Added constraint: Linking transformer station capacities.")
+        constraints_custom.constraint_equate_bidirectional_transformer_capacities(
+            model, 
+            case_dict, 
+            bus_electricity_ng_feedin, 
+            bus_electricity_ng_consumption, 
+            pointofcoupling_feedin, 
+            pointofcoupling_consumption, 
+            PCC_FEEDIN_FIXED_CAPACITY, 
+            PCC_CONSUMPTION_FIXED_CAPACITY
+        )
+    
+    # ------------Link rectifier and inverter capacities constraint------------#
+    if case_dict[USE_BIDIRECTIONAL_INVERTER_CONSTRAINT] != None:
+        if case_dict[USE_BIDIRECTIONAL_INVERTER_CONSTRAINT] is True:
+            logging.info("Added constraint: Linking rectifier and inverter capacities.")
+            constraints_custom.constraint_equate_bidirectional_transformer_capacities(
+                model, 
+                case_dict, 
+                bus_electricity_dc, 
+                bus_electricity_ac, 
+                inverter, 
+                rectifier, 
+                INVERTER_DC_AC_FIXED_CAPACITY, 
+                RECTIFIER_AC_DC_FIXED_CAPACITY,
+                experiment[INVERTER_RECTIFIER_CAPACITY_RATIO_FACTOR]
+            )
+            if experiment[RECTIFIER_AC_DC_COST_INVESTMENT] != 0:                
+                logging.warning(
+                    "Case definition of "
+                    + case_dict[CASE_NAME]
+                    + ": Are you sure that you want to define both rectifier and inverter costs if "
+                    + "you link the capacties to receive a biderectional inverter? "
+                    + "This would result in effective investment costs of "
+                    + str(float(experiment[RECTIFIER_AC_DC_COST_INVESTMENT])+float(case_dict[INVERTER_AC_DC_COST_INVESTMENT]))
+                    + " currency/kW bidirectional inverter."
+            )
     # ------------Force charge from maingrid------------#
     if case_dict[FORCE_CHARGE_FROM_MAINGRID] is False:
         pass
@@ -497,6 +540,7 @@ def build(experiment, case_dict):
             + " faulty at enable_inverter_at_backout. Value can only be True or False"
         )
 
+
     """
     # ------------Allow shortage only for certain percentage of demand in a timestep------------#
     if case_dict['allow_shortage'] is True:
@@ -507,6 +551,7 @@ def build(experiment, case_dict):
             shortage_constraints.timestep(model, case_dict, experiment, sink_demand_dc, 
                                           source_shortage, bus_electricity_dc)
     """
+
     return micro_grid_system, model
 
 
diff --git a/src/G2b_constraints_custom.py b/src/G2b_constraints_custom.py
index debfbff..9e5a0af 100644
--- a/src/G2b_constraints_custom.py
+++ b/src/G2b_constraints_custom.py
@@ -4,6 +4,7 @@
 import pyomo.environ as po
 import logging
 import pandas as pd
+import oemof.solph as solph
 from src.constants import (
     SHORTAGE_LIMIT,
     NUMBER_OF_EQUAL_GENERATORS,
@@ -954,6 +955,18 @@ def inverter_only_at_blackout_test(case_dict, oemof_results, e_flows_df):
 
     return
 
+# equate bi-directional transformer capacities
+def constraint_equate_bidirectional_transformer_capacities(model, case_dict, bus_transformer_in, bus_transformer_out, transformer_in, transformer_out, name_transformer_in, name_transformer_out, factor = 1):
+    CAP_inverter = 0 
+    CAP_rectifier = 0
+    if case_dict[name_transformer_in] != None and case_dict[name_transformer_out] != None:
+        if case_dict[name_transformer_in] is False and case_dict[name_transformer_out] is False:
+                CAP_inverter += model.InvestmentFlow.invest[bus_transformer_in, transformer_in]
+                CAP_rectifier += model.InvestmentFlow.invest[bus_transformer_out, transformer_out]
+    solph.constraints.equate_variables(model,CAP_rectifier, CAP_inverter, factor)
+
+    return model
+
 
 # todo shortage constraint / stbaility constraint only relates to AC bus
 def timestep(model, case_dict, experiment, el_bus, sink_demand, source_shortage):
diff --git a/src/constants.py b/src/constants.py
index f76cce0..f7431d0 100644
--- a/src/constants.py
+++ b/src/constants.py
@@ -110,6 +110,7 @@
 INVERTER_DC_AC_COST_VAR = "inverter_dc_ac_cost_var"
 INVERTER_DC_AC_EFFICIENCY = "inverter_dc_ac_efficiency"
 INVERTER_DC_AC_LIFETIME = "inverter_dc_ac_lifetime"
+INVERTER_RECTIFIER_CAPACITY_RATIO_FACTOR = "inverter_rectifier_capactiy_ratio_factor"
 MAINGRID_DISTANCE = "maingrid_distance"
 MAINGRID_ELECTRICITY_PRICE = "maingrid_electricity_price"
 MAINGRID_EXTENSION_COST_INVESTMENT = "maingrid_extension_cost_investment"
@@ -308,6 +309,7 @@
 WIND_FIXED_CAPACITY = "wind_fixed_capacity"
 RECTIFIER_AC_DC_FIXED_CAPACITY = "rectifier_ac_dc_fixed_capacity"
 INVERTER_DC_AC_FIXED_CAPACITY = "inverter_dc_ac_fixed_capacity"
+USE_BIDIRECTIONAL_INVERTER_CONSTRAINT = "use_bidirectional_inverter_constraint"
 ALLOW_SHORTAGE = "allow_shortage"
 STABILITY_CONSTRAINT = "stability_constraint"
 RENEWABLE_CONSTRAINT = "renewable_constraint"