diff --git a/edisgo/flex_opt/battery_storage_operation.py b/edisgo/flex_opt/battery_storage_operation.py
index 64447a8fd..086dec1f8 100644
--- a/edisgo/flex_opt/battery_storage_operation.py
+++ b/edisgo/flex_opt/battery_storage_operation.py
@@ -164,6 +164,41 @@ def apply_reference_operation(
     if storage_units_names is None:
         storage_units_names = edisgo_obj.topology.storage_units_df.index
 
+    if (
+        edisgo_obj.topology.storage_units_df.loc[
+            storage_units_names, "efficiency_store"
+        ]
+        .isna()
+        .all()
+    ):
+        logger.warning(
+            "The efficiency of storage units charge is not specified in the "
+            "storage_units_df. By default, it is set to 95%. To change this behavior, "
+            "first set the 'efficiency_store' parameter in topology.storage_units_df."
+        )
+
+        edisgo_obj.topology.storage_units_df.loc[
+            storage_units_names, "efficiency_store"
+        ] = 0.95
+
+    if (
+        edisgo_obj.topology.storage_units_df.loc[
+            storage_units_names, "efficiency_dispatch"
+        ]
+        .isna()
+        .all()
+    ):
+        logger.warning(
+            "The efficiency of storage units discharge is not specified in the "
+            "storage_units_df. By default, it is set to 95%. To change this behavior, "
+            "first set the 'efficiency_dispatch' parameter in "
+            "topology.storage_units_df."
+        )
+
+        edisgo_obj.topology.storage_units_df.loc[
+            storage_units_names, "efficiency_dispatch"
+        ] = 0.95
+
     storage_units = edisgo_obj.topology.storage_units_df.loc[storage_units_names]
     soe_df = pd.DataFrame(index=edisgo_obj.timeseries.timeindex)
 
diff --git a/edisgo/io/storage_import.py b/edisgo/io/storage_import.py
index 2ba1716cf..e5031ed24 100644
--- a/edisgo/io/storage_import.py
+++ b/edisgo/io/storage_import.py
@@ -73,7 +73,13 @@ def home_batteries_oedb(
         )
         batteries_df = pd.read_sql(sql=query.statement, con=engine, index_col=None)
 
-    return _home_batteries_grid_integration(edisgo_obj, batteries_df)
+    names = _home_batteries_grid_integration(edisgo_obj, batteries_df)
+
+    edisgo_obj.topology.storage_units_df.building_id = (
+        edisgo_obj.topology.storage_units_df.building_id.astype(int)
+    )
+
+    return names
 
 
 def _home_batteries_grid_integration(edisgo_obj, batteries_df):
diff --git a/examples/edisgo_simple_example.ipynb b/examples/edisgo_simple_example.ipynb
index c7ee79ce1..31b493ead 100644
--- a/examples/edisgo_simple_example.ipynb
+++ b/examples/edisgo_simple_example.ipynb
@@ -892,7 +892,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.5"
+   "version": "3.11.0"
   },
   "toc": {
    "base_numbering": 1,