(background: I'm just playing with numbers, trying to estimate how many solar panels would be needed to fully supply the energy for a home and 2 Tesla cars)
I've been reading up on solar panels and on Tesla car charging. That page mentions that the conversion efficiency from DC (solar panel) to AC (what home appliances need) is 75-80%.
On some Tesla forum somewhere I read that the charging efficiency from the wall plug to the car is around 85% (can anyone confirm this?). Can I conclude from this info that a Tesla car is actually a DC device?
So, if I understand all of this correctly, I lose ~25% to convert solar panel energy from DC to AC (selling to the utility company) and then again ~15% to charge the car battery from the wall plug (buying from the utility company).
Is it possible to avoid both of these conversion steps by charging a Tesla Powerwall from the solar panels during the day, and then charge the car from the Powerwall during the night? (avoiding the energy grid completely, no net metering considerations)