I think your math is off some how. I have a Model 3 and two Leafs and we charge them from our 39 400 Watt panels without trouble. They are always ready to go fully charged unless one of the boys has been doing more than normal of driving to the beach with a girlfriend and then borrowing the Model 3 for a concert, or whatever fun involves using all the stored energy at the same time (e.g. not commutes to school or work).