The solar panels on both the install that I did and the Professional Install on the Cuchara that we just bought both only connect their grounds to the solar controller and nowhere else. I've never seen anything that suggested the solar panel ground be connected to chassis/camper ground and I dimly recall reading somewhere a long time ago specifically to NOT do that. If I could only recall here that was I'd dredge it up or prove my memory faulty.
Most charge controllers I know of are so called "positive ground" (just like old British cars), i.e., the positive terminals for solar panel, battery, and load function (if your model offers one) are tied together in the controller; the negative connections "float". This makes the electronics and control much simpler and affordable. Do not ground the controller in these type devices. This is also why the charge controller cannot monitor your load current.
Edited by Bosque Bill, 12 March 2019 - 02:12 PM.