An electric car doesn't need an inverter, it can charge directly off the produced DC. Nor does it particularly need a "whole assembly" for mounting etc, as it

An electric car doesn't need an inverter, it can charge directly off the produced DC. Nor does it particularly need a "whole assembly" for mounting etc, as it would be built directly into the roof of the car. It may well be that using a solar panel to replace the metal skin of the car will turn out to be equal or less weight than it otherwise would be, though of course much more expensive.