On the move, the engine alternator is all that is needed, but parked that is not the case and running the engine just to charge the batteries is expensive and unpleasant for any neighbours. A motor-home (RV) solar system is then very attractive. There are 2 solutions:

1. Install flexible solar panels on the roof and connect them to a solar controller that charges the 12v batteries, OR
2. Use a portable power station system for all domestic needs, charging it either from roof mounted panels or the portable type that are more expensive but need no installation and are easily placed to optimise solar charge.