> You are missing something important: they are storing enough heat to last for a couple weeks of no wind (or a cold snap). Enough DC batteries to heat a house

> You are missing something important: they are storing enough heat to last for a couple weeks of no wind (or a cold snap). Enough DC batteries to heat a house that long are expensive and dangerous (fire hazard). A large water tank (10 tons of water or more!) is a lot safer to have around the house. Why would you use batteries? That’s silly, you’d simply heat water in both scenarios.