I installed 520 watts of solar panels on my motorhome. They work great for boondocking, and the cost of the panels has dropped dramatically in recent years. There is lots of information available on the internet for RV solar, so you will want to do some research.
The panel wiring is usually 10 gauge, and has insulation that is resistant to sun exposure suitable for outdoor use on a roof. The wire will be marked as "UL 4703 photovoltaic". You will want to use much larger gauge wire from the roof junction box to the charge controller in the RV basement which needs to be as close as possible, but never in the same compartment as the batteries. Typically 4 or 6 gauge wire is used for this part of the installation to minimize the voltage drop. Try to keep the wire length as short as possible where practical.
The solar panels must be located so they are not shaded at all. Even a small amount of shadow from a vent cover, air conditioner, or TV antenna will severely reduce or completely eliminate the power output. People mistakenly think that if 90% of the panel is in the sun, it is producing 90% of its rated power. Most panels are made of individual cells wired in series. If one cell gets shaded, it can take out the whole panel. It is just like those old Christmas tree lights, where if one bulb burned out, the hole string didn't work...
Solar panels are rated for standard conditions, which makes comparison easy, but those conditions often do not exist in actual usage. Panels mounted on an RV roof will likely not be aimed perfectly at the sun, so expect lower output. The panels are also de-rated as temperature increases. On a hot day, a panel might put out only 75% of its rated value. The reverse is also true in cold weather, where a panel might produce 110% on a cold clear day.
This picture shows the solar charge controller, a disconnect box, and a 300 watt inverter installed in a basement compartment in my motorhome. The batteries are located outside of the compartment behind the wall, so they are as close as possible to the charge controller and inverter.
2010 Georgetown 373
2013 Jeep Wrangler