diff --git a/src/apps/smart_grid/SmartOpcServer.cpp b/src/apps/smart_grid/SmartOpcServer.cpp
index 58854c7cf094ee5ba9c5590e9a94fb8bfaf3b683..d66dc9df736b81d193a318a605f1a3d7c8541909 100644
--- a/src/apps/smart_grid/SmartOpcServer.cpp
+++ b/src/apps/smart_grid/SmartOpcServer.cpp
@@ -72,7 +72,7 @@ void SmartOpcServer::setup_server()
     m_sun = m_state.AddVariable(m_idx, "sun-Power", Variant(m_state_machine.m_model.get_sun()));
     m_wind = m_state.AddVariable(m_idx, "wind_power", Variant(m_state_machine.m_model.get_wind()));
     m_power_production = m_state.AddVariable(m_idx, "power_production", Variant(m_state_machine.m_model.get_power_production().sum()));
-    m_usage = m_state.AddVariable(m_idx, "used_power", Variant(m_state_machine.m_model.get_power_usage()));
+    m_usage = m_state.AddVariable(m_idx, "used_power", Variant(m_state_machine.m_model.get_power_usage().sum()));
     m_excess_power = m_state.AddVariable(m_idx, "excess_power", Variant(m_state_machine.m_model.get_excess_power()));
 
 
@@ -107,7 +107,7 @@ void SmartOpcServer::run_server()
         m_sun.SetValue(Variant(m_state_machine.m_model.get_sun()));
         m_wind.SetValue(Variant(m_state_machine.m_model.get_wind()));
         m_power_production.SetValue(Variant(m_state_machine.m_model.get_power_production().sum()));
-        m_usage.SetValue(Variant(m_state_machine.m_model.get_power_usage()));
+        m_usage.SetValue(Variant(m_state_machine.m_model.get_power_usage().sum()));
         m_excess_power.SetValue(Variant(m_state_machine.m_model.get_excess_power()));
         m_time.SetValue(Variant(m_state_machine.m_model.get_time()));
         m_producing.SetValue(Variant(m_state_machine.m_model.get_producing_state()));