The architecture I described does not imply that those batteries will be loaded by locally-installed solar panels. There will be a grid, as usual, carrying electricity produced by the described mix, mostly by industrial sites (in many geographical areas a large part of it will be offshore wind turbines fleets).

So electric car owners are in effect sponsoring electricity storage?

No: they are benefiting from it as they (most of the time) load their batteries when electricity is cheap, and discharge it into the grid when it is rare and therefore expensive.

On average the car autonomy already is way above the daily commute, and this margin is quickly growing.

There are more and more parking places (private and public) connected to the grid.

A bit of intelligence ( https://en.wikipedia.org/wiki/Smart_grid ) will orchestrate.

> No: they are benefiting from it as they (most of the time) load their batteries when electricity is cheap, and discharge it into the grid when it is rare and therefore expensive.

This would only work if the added charge on night-time electricity also accounts for battery cycling cost which I doubt it would.

Very low or even negative prices, during episodes of renewables overproduction (typically when wind blows or sun shines way over demand), are more and more common.

https://en.wikipedia.org/wiki/Negative_pricing#Electricity

Reciprocally as more and more less tolerated grid backup (greenhouse-gas emitting fossils or dangerous nuclear) disappear episodes of under-production will be more common, and during those electricity price will soar.