Part of my math, too, is that my solar inverter has a feature to power only certain circuits (a separate circuit panel) only on the condition that my home batteries are at least X% charged. So if I or my wife come home in the EV and have, say, 2/3rds still "in the tank" and plan nothing but short drives around town the next few days -- we'll plug it into an outlet that's powered only when the home solar has excess (say 80% or more charged). If we come home with a low EV charge or if we plan to drive a lot the next day, we'll plug it into a normal constant power outlet (knowing that some of that power will be pulled from the grid).
So if we plug it into the excess power circuit we'll plug it in knowing that it may not get any charge at all. Or maybe some for a while until the home battery charge level is below the threshold. Likewise with it automatically start charging the next day after the sun comes up if the EV is already plugged into the excess-power outlet (say if I work from home the next day or it's an off day and I'm outside cutting grass, while my wife is either at home or taking the gas car on a day or two trip to visit family).
But this math works only if you live in the south where we get plenty of sun and don't consume as much power at night for heat (I do some this time of year, but my variable speed heat pump usually keeps up with the cold without having to power the heat strips). Here in the south a huge portion of our power is used for A/C about half the year. Since a lot of that is during the daytime and since that half of the year has long daytime days, there's less need for battery power to stay cool.
And since the days it rains or is cloudy tend to also be mild temperature days I don't have to run the A/C or heat as much on days I get little solar power. That's why it currently provides half the power we consume.
Wow, very cool set-up. Thanks for explaining.