Chris

I had a chat with a bloke over the street from me about this the other week. He works for our local DNO so he knows his stuff (has geek-level control with a 3rd party app that gives him access to all sorts of smart stuff in his house). He paid out about £6k for 10kW of battery, *without* power-cut backup because that costs more (mostly, some quite complicated attritional switching and wiring on your fuse box to ensure the thing switches over safely and legally during a power cut). He is expecting the up-front investment to pay back in about 7 years. He pointed out that the money you spend on it would actually yield more if you invested it. He did it because he’s a systems nerd and because he can.

If your interest is continuity of supply in the event of a power cut there are other things you can do - with the right research (and never admitting to anyone you’re actually doing it) you can run a cable from your EV if you have one into a 3-pin socket in your garage and run bits of your house that way. There are many caveats to doing that safely of course. Safer would be to buy a 3kW camping battery and keep it charged, and run essentials off it if/when needed. You then also have a useful bit of kit you can take with you on days out etc.