9.1 kW system installed in August last year with a promised minimum generation of 13000 kWh. I add all the monthly generation numbers from the solar city app and come up with ~14300 kWh. When I check the electricity bill, my one year consumption from 08-17 to 08-18 is ~8800 and net surplus generation is -700 kWh, which translates to a total of ~9500 kWh recorded . My question is: where did the ~3800 kWh difference go? Is there a loss in transit coming from the solar panels back to the grid?