Did you know the Nissan leaf electric vehicle has a solar panel on the rear spoiler?
Based on it’s size, I’d assume the amorphous solar panel is only generating 5-7 watts. Not a lot of power but enough to keep the 12v lead-acid battery topped up if the car isn’t driven for a long time.
The main drive battery of the leaf is lithium-ion based but the battery used for central locking, wipers and other related systems is actually a regular 12v lead acid battery.
The solar panel won’t extend your driving range but it does mean you don’t have to worry about coming back from holiday to find you can’t unlock your car.