I like the idea - but then wouldn't it be nice if your fridge had battery backup in case power went out? or your washing machine could charge cheaply overnight and run during the day?

And then I start to think that maybe the better solution would be a smaller version of something like a powerwall. Maybe something flat that would easily fit behind the kick-board under the units in the kitchen and then could be wired up to provide multiple uses.

Or maybe add a couple of sockets to that induction hob, that let you use it as a UPS for your fridge? Boiling water in 40 seconds might be fun, but doesn't strike me as a killer feature. Only time I've ever wanted a more powerful hob myself, is when I've got my wok out.