You could also potentially use them as a solution for more efficiently allocating energy, less by pumping energy back into the grid, and more by running home power from the car battery during peak hours, rather than having to produce too much energy during off hours, having to shut down the power during peak hours or provide limited access, or having to provide power for less people. You can make the power go further, and especially for renewables which have potentially less consistent energy production (the nice part being that peak demand roughly lines up with peak production for solar power, at least, in the summer). But none of that’s really an attractive proposition to the american car buyer who wants to travel as far as possible at the drop of a hat, and you have to make car batteries larger and the cars themselves less efficient to compensate for this power draw and power storage that may or may not be happening at any given moment, so it’s sort of self-defeating with the american car market.
Obviously, it isn’t really a more equitable or more efficient solution broadly than doing something like pumping water uphill. Or trying to limit demand in the first place by decreasing surface area of homes, by moving towards multiple units in one building, increasing r-values by using better building materials you could shell out for with a larger amount of occupants, yadda yadda urban design garbage. Stuff that generally is antithetical to car-centric infrastructure and thus electric cars. You also potentially run into problems where the as the grid as a whole becomes less relied upon, they make less money, and then the grid starts to fail further in a positive feedback loop. Poor people can’t afford rooftop solar and electric cars, because most of them can barely afford rent and aren’t really the ones making those decisions anyways.