I have a 12v system in a RV that is electrically isolated from the vehicle, meaning they don't share a common negative on the chassis. I have a 100/30 MPPT that has a grounding screw on the side, should I connect this to my house batteries negative or the chassis of the vehicle even though it doesn't form a closed loop?
Should a fault occur in the MPPT and its housing becomes live no current cant flow via you into the RV because the path is not complete. The only way you can complete the path is if you were to touch the MPPT housing with one hand and with your other hand the battery negative or PV negative.
I would recommend for you to connect the MPPT grounding screw to the battery negative.
But, be aware that, if the MPPT is mounted to a metal surface, the instance you connect the grounding screw to the battery negative you will also have created a connection between the RV chassis and the battery negative. This might be undesirable. In that case connect the ground screw to the chassis.
Just to confirm your answer... I am using my vehicle chassis (connected to a common negative bus bar) as the main ground for my system, thus I should connect BOTH the grounding screw (on the side of the MPPT unit) and the MPPT Battery Negative to my negative bus bar... is this correct?
