I installed an off grid system on my sailboat and I have doubts about the grounding of the solar board and the mppt controller. there must be a ground point outside the hull of the boat or simply connect the ground point of the equipment to the negative battery, remembering that the negative of the battery is not connected to any physical point of the boat.
Hi; please check the question called Wiring Unlimited; posted a few days ago.
It has a chapter on grounding
To add to the recommendation to look at the wiring unlimited book, here's three scenarios of interest in earthing. In all cases the onboard grounding point should be in contact with the earth reference. The earth reference is defined relative to the 110V/240V/whatever AC system(s) that are onboard and/or sourced from the grid.
1) In water, shore power connected
2) In water, shore power disconnected
3) Laid up in yard
The exact needs may differ according to local regulations.
