I installed the solar panel atop our Casita. It's a SunForce 15-watt cell that fits neatly in the trough behind the awning. I had to drill four holes through the roof to install it.
The 14-volt passes through the ceiling and plugs into a accessory power outlet. I have a 7-amp controller in line to keep the battery from over-charging.
We keep the Casita in a commercial storage site. I had been recharging the battery every two weeks. Before trips, I had to remove the battery and bring it home for charging. Now I can keep the battery hot. I can even turn on the refrigerator before leaving and allow solar energy to keep the battery topped off.
Now we can even charge the battery while travelling down the road.
I would like to add more solar panels and have enough energy to keep fans and conviences running while dry camping.