I looked battery storage when I had solar panels fitted to the house roof…. but the cost wasn’t justifiable at the time.
Domestic solar schemes are already selling energy back to the grid so I’m sure it won’t be long before we do the same with EVs.
Using idle capacity in EV batteries at peak times and then charging overnight at off peak times seems like a very good way of levelling out supply demand.
I presume that the main issue is getting the metering right so that the EV owner doesn’t profit from charging overnight at off peak rates and generating at peak rates.