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The water heater trick of using the cold air is supplemented by the fact that my home uses a variable speed heat pump with a variable speed air handler (and electric heat strips for the few winter nights that it gets too cold for the heat pump). In other words, my HVAC fan is always running even if slowly-- so there's never a time of day when the water heater dumps free cold air that's not picked up by the HVAC. Bonus points that the water heater draws only 300W to 350W (though it can run a few hours). That means it's a drop in the bucket for my inverters being able to provide 18kW continuous power before they have to pull from the grid. (All the rest of my power draw from the remaining appliance and such have to exceed 17.6 kW before they exceed the 18kW max of my inverters and I wind up pulling from the grid.) The idea is for the home solar/energy savings system as a whole to work better than the sum of its parts.

For charging the EV (which we do most of our driving in, though we have an ICE pickup too), I have two 240V outlets to charge with. One is constantly powered (regardless of the weather) and the other is intermittently powered (when my home solar batteries are charged at least 70% SOC, though that's configurable).

When we come home with the EV and have more charge than we need the next day, we plug it into the intermittent outlet. That may or may not get a charge, and if it gets a charge it may or may not charge all the way ("all the way" is usually 80% as per EV spec). The good part of that is, however much charge we get, it's free. But if we come home and don't have enough charge for the next day we plug it into the constantly powered outlet. We do that knowing the charge may or may not be free (it might add to our power bill), but is certain to be charged. That one trick alone makes almost all of our EV charging free. Average driving 30-40 miles per day, which gives us 3 days worth of leeway between the EV's 230 miles "top off" range and the 120 mile lower limit my wife is comfortable with (her "range anxiety") for random driving chores the next day. That charging trick makes the EV and solar work together better than the sum of their parts.

This part can't be overstated. The more independent you are from things the bureaucrats regulate (in this discussion it's about energy) the more you get to be the "regulator" to make it work best for your situation. That's the main reason decentralized solar and an EV works way better for us than grid dependent solar and public funded charging stations even in climates that are as good for solar as ours.