People here doesnt seem to know how little power you use in a home relative to a running car. To say thats its going to use and drain your cycle life is unfounded (might as well not use your car then)

EV rejuvenating back to the grid is an excellent idea except Tesla doesnt buy that idea because it will cannibalize their Powerwall sales

There is already a lot of effort to convert used ev batteries to become in house home battery
https://github.com/dalathegreat/Battery-Emulator