No question that night is the natural time to do it. But if we have an all electric fleet, the demand at night will get high, and the price will go up until it pushes more people not to charge at night.

In a grid that's all renewable, night power will be only nukes and storage. But it's unclear how many more nukes we will build. (Hydro is a combination of renewable power with "built in" storage in that you can choose when you release it but you want to release as much energy as nature gave you so you might release at night.) And the night wind definitely wants somewhere to put its energy. But California still pulls around 19gw at night without very many electric cars.

On the other hand electricity is a pretty cheap way to power cars. So if storage is cheap and can be built, and it costs a small amount to put energy into the storage and get it out, some people will pay that for the convenience. But most cars, other than taxis, stay parked most of the day, just not as reliably as the night.