Note down the all connected load with inverter & calculated the actual running load of inverter.
Exmp. 5nos. of 20 watt CFL, 3 nos. of 60 Watt fan & One TV 200 watt & 1000 watt AC are running with inverter than the inverter load are 1480 watt. However efficiency of connected equipment assumed 0.9 than actual inverter load is 1650 watt.