content: You don't install all this stuff and carry on burning energy like you did before. Energy saving appliances, timers on stuff that doesn't need to be on over night, insulate, get rid of inefficient heating and cooling systems. All of that means you can easily run a modern house on a lot less than 20kWh a day. That said, I don't think the powerwall is good value and intend to use my EV as a battery for my house because it has a much bigger battery than the powerwall does plus if my solar isn't generating enough to get by I can drive down to the local chargepoint and fill up to keep me going. Not planning to go off grid as yet because it is too expensive but I am generating more power than I use and I still have to get full insulation and double glazing in.