It is important to ground your PV system as in the event of any failure there is a safe path for the fault current to circulate. To ground your PV system in an RV you can use the chassis as a reference point. Connect all the aluminum frames of the solar panels and run it down to the chassis where busbar terminals can be installed to make the connections of the grounding wires. Make sure that the surface where the ground terminals will make contact are cleaned and free from oxide or paint. Then, the inverter and charge controller will also have grounding terminals for you to connect the green wire conductors. The grounding cables must be copper and they must be a minimum of #8AWG gauge conductor.