A solar roof wouldnt be much use. I own a few sites that generate power for the Government. My home even has a setup. I am generating 5kwh max on my home system. There is a 90kwh version and a 85kwh of the Tesla. I have read that they only charge 75%. That said - In the peak of summer - the 25 panels on my roof would create a max of 50kwh over 10 sun hours (not enough to fill the car) - and that is assuming you are leaving your car in the garage all day... Cut those number in half for the winter - and adjust for days when snow covers them!