fixed common area metric

app.py

@@ -80,7 +80,9 @@ def financial_analysis(
         grid_offset = min(grid_purchased, storage)
         grid_purchased -= grid_offset
 
-    monthly_savings = (consumption - common_area) * st.session_state.grid_price / 100
+    monthly_savings = (
+        (consumption - (common_area * 30)) * st.session_state.grid_price / 100
+    )
     total_investment = (
         st.session_state.solar_panels * st.session_state.panel_price
         + st.session_state.batteries * st.session_state.battery_price