diff --git a/pv_assessment/pv_system_assessment_with_lcoe.py b/pv_assessment/pv_system_assessment_with_lcoe.py
index 3fecc3c4..d775fde9 100644
--- a/pv_assessment/pv_system_assessment_with_lcoe.py
+++ b/pv_assessment/pv_system_assessment_with_lcoe.py
@@ -164,17 +164,16 @@ class PvSystemAssessment:
     total_hourly_pv_output = [rooftops_pv_output[i] + facades_pv_output[i] for i in range(len(electricity_demand))]
     imported_electricity = []
     exported_electricity = []
-    self.building.self_sufficiency['hour'] = []
+    self.building.self_sufficiency['percent'] = []
     for i in range(len(electricity_demand)):
       transfer = total_hourly_pv_output[i] - electricity_demand[i]
-      self.building.self_sufficiency['hour'].append(transfer)
       if transfer > 0:
         exported_electricity.append(transfer)
         imported_electricity.append(0)
       else:
         exported_electricity.append(0)
         imported_electricity.append(abs(transfer))
-    self.building.self_sufficiency['year'] = sum(self.building.self_sufficiency['hour'])
+    self.building.self_sufficiency['percent'] = sum(total_hourly_pv_output) / sum(electricity_demand) * 100
 
     results = {
       'building_name': self.building.name,