There have been eye-popping reductions in the cost of PV systems in recent years. Urban PV on rooftops (on the retail side of electricity meters) threatens the business models of utilities. Some jurisdictions are engaged in pushback, and offer low feed-in tariffs (~8 cents/kWh c/f 20-30 c/kWh general tariff). This encourages self-consumption (thus avoiding the general tariff). Some companies now sell low cost battery systems to increase the self-consumption share. In addition to delivery of electricity, PV systems on domestic rooftops appear to be able to deliver both water heating and space heating competitively with gas, solar thermal and conventional electric systems, via operation of heat pumps. Surprisingly, direct resistance heating using PV electricity might soon be cost effective! Heating is a large load with low cost storage. This project will explore the economic feasibility of rooftop PV systems to minimise sale of excess electricity to the grid at low prices by maximising self-consumption.