I have long been very interested in the question of how much it (does not) matter(s) when one plugs one's electric vehicle in, especially if, like I do, I have the choice of plugging into a home rooftop solar system.
Many years ago, I wrote extensively on this web site/blog about the many intricacies and complexities of what I call "solar offset" charging of an electric vehicle vs. directly filling up with electricity that has been/is being produced directly by a (home rooftop) solar system connected to the same electrical box into which an EV charger and/or the wall-socket into which you're plugging your EV into.
So, a new 20 kW solar system with two separate arrays on two separate roof areas, including a set of garages, is going up in our Highline Crossing Cohousing Community here in Littleton, Colo. :-)
Precisely 10 years ago to this month, REC Solar workers were on the rooftop of my Aurora, Colo. home installing a 5.5 kW solar system that is still there. The system outlasted me -- or, at least my marriage -- and is still there, pumping out clean, green electricity for the residents who bought the home from me and my now ex-wife in November of 2015, which we sold following a August 2015 divorce.