Update SimSolarBattery.lua

Lost energy calculation resulted in a negative value, instead of a positive value.

SimSolarBattery.lua

@@ -3,7 +3,7 @@
 --version 0.1.2 05-04-2021: changed a check for latest data storage from seconds to milliseconds to accommodate meters that update every second
 --version 0.1.3 05-04-2021: Added a check to avoid big deviations in calculation when inverter power level is small while having
 --	also a small script interval. Added more debug logging
---version 0.1.4a 09-04-2021: Description text fix + little preparation for future release
+--version 0.1.4b 10-04-2021: Description text fix + little preparation for future release
 
 --To be created virtual devices in the hardware section of Domoticz:
 	local solarBattery_name = 'Virtual Solar Battery'			-- (1) Virtual 'Custom Sensor' device name for the 'Virtual Solar Battery'. Change axis label to kWh
@@ -238,7 +238,7 @@ return {
 	domoticz.log('Energy balance = '..energyBalance..' Wh (negative = consumption)',domoticz.LOG_DEBUG)
 
 	if energyBalance > maxBbatteryInverterEnergy then
-		inverterLostEnergy = maxBbatteryInverterEnergy - energyBalance
+		inverterLostEnergy = energyBalance - maxBbatteryInverterEnergy
 		domoticz.log('Positive energybalance above max inverter capacity. inverterLostEnergy = '.. energyBalance  ..' - ' ..maxBbatteryInverterEnergy .. ' = ' .. inverterLostEnergy, domoticz.LOG_DEBUG)
 		energyBalance = maxBbatteryInverterEnergy
 		batteryProdWatt = battery_inverter_power.value