@nprofile1q... Oh, you have to manually switch over? The systems I know either run in parallel to the grid, so they compensate for loads while there's energy in the battery, or (less common) the whole installations is behind the inverter and it does automatically disconnect from the grid when that goes off; which it does about once every year for a few minutes, at most. That also means should I ever need more power than my inverter can deliver, the rest comes from the grid.