[SOLVED] Can you attach solar panels to an electric RV and use that to charge the engine battery?


The solar panels typically charge batteries in an RV. The batteries can provide AC power to devices via an inverter. No RV inverters, that I am aware of, can power AC. Laptops are okay. Refrigeration is a maybe.

Generators, or shore power, are needed to power larger items for any length of time.

What are you trying to accomplish? And, for how long?
While in theory this is possible, your first step should be to make a very detailed energy budget. You may find that the necessary panel area is too large for the RV's roof, the wanted loads require a battery larger than you have or can install, or just that one part or another (inverter, panels, batteries) ends up being cost prohibitive.

Only once you've done that should you really start looking at controls, system layouts etc.
Average roof solar panel produces about 200W under ideal conditions. If you can install five of these on the roof, you'll get 1KW of power. As other said - you'll need separate power controller, battery pack, and inverter, to power appliances. Don't touch engine battery - it has enough job starting your engine.