I have a modest set of solar panels on an entirely ordinary house in suburban London. On average they generate about 3,800kWh per year. We also use about 3,800kWh of electricity each year. Obviously, we can't use all the power produced over summer and we need to buy power in winter. So here's my question: How big a battery would we need in order to be completely self-sufficient? Background …
they use heating. I should of just said heating.
Most homes here are heated with gas - ours is.
So electricity doesn’t factor in to heating (other than a tiny amount for controlling the boiler and thermostat).