I have 6.6kW PV panels, 5kW inverter and Catch relay to divert excess solar to hot water system, System working well, ten north panels and five west. No shading. I export FIT every day, average over time is more than 10kWh per day. Some online calculators suggest I would not pay for a battery via grid use saving over 10 years. I have heard that the biggest saving amount comes from installing panels and diverting excess solar to hot water system, which I have done. However I have also heard that ...