> Even that won’t be enough.
It looks like you're right that just covering the store and parking lot in panels wouldn't be enough. But then you've got two possibilities. One is the store is in the city, and then it can be on the grid, because there is always going to be a grid in the city. The other is the store isn't in the city and then you've got cheap land next to the store to fill with panels and turbines.
> Grid is also useful for time shifting power demand/production to smooth out the morning/evening dips, for space-shifting production to deal with clouds etc., and (assuming wind is part of the solution) the best wind resources aren’t where you actually want to build houses.
But batteries (especially when they're in cars) do the same thing. Your house may not be on the grid, but it's got panels on it that power it during the day, meanwhile your car is out getting charged up somewhere else, and you use that power at night.
Electric car typically has a >50kWh battery, which will power a typical household for about two days on its own, call it twice that if the house runs on its own panels during the day. So as long as you get the equivalent of a full charge twice a week, that's all you need, right?