A run of cold, cloudy days was the ideal opportunity to program the SolarEdge inverter to import offpeak power to charge the battery at night. Without this option, I would have paid peak power rates for electricity the next day when solar production wasn't able to meet household demand.
The day we switched on the solar power system was the culmination of a long design and installation process. Clever solar panels maximise electricity production while the inverter/battery keeps the lights on at night. The aim is to minimise importing grid electricity but export as much solar power as we can.
Installing solar cells and then fitting a battery storage system might be worth a few greenie points, but is the extra cost justified on a purely economic analysis? Not yet maybe, but current trends indicate that time isn't too far in the future.