How to ground a solar charge controller and solar panels to a vehicle? More details... Solar Powered, Electric Tractor?

Solar Charge Controller problem... For my university capstone project, my team and I are converting last year's DIY conversion electric tractor into a self-sustainable solar powered, electric tractor. Yes, we will be mounting solar panels on a tractor. It will not be for agricultural uses (yet) but it will operate as a campus' fleet service. We have four 12v deep-cycle batteries (total 48v) that will be charged with two 290v polycrystalline solar panels. The solar charge controller manual said that we needed a GFDI (ground-fault detector interrupter) because of an UL compliance but we learned that it's for residential installations... One of teammate was told that we should not ground the controller onto the tractor but he doesn't know why... is that true? We are all solar amateurs. We know how a car is ground and why things need to be ground, but if we don't ground the controller into the tractor, where can we ground it? Help...? Please and thank yous. :) I will gladly provide more information if needed. 

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Given you have a US address to deal with, I think you should call the suppliers in PA for their final professional advice. Mine would be certainly NOT to ground the PANELS to the chassis of the vehicle, but you should be able to ground the battery -ve to the chassis. Bear in mind that in full sun, that panel voltage can kill easily.

The manual says, of the ground in the system "Do not connect the system negative conductor to this terminal. NEC requires the use of an external ground fault protection device (GFPD). The TriStar MPPT does not have internal ground fault protection. The system electrical negative should be bonded through a GFPD to earth ground at one (and only one) location. The grounding point may be located in the solar circuit or the battery circuit."

Now, a GFPD is USUALLY an AC device, so you have to be careful to find a DC switching one. The GFPD will measure the difference in current flow from your +ve terminal to your -ve terminal. If there is a small imbalance, it will shut down automatically. Ask yourselves, for your connections, how you will make sure that can happen.

As you can imagine, a definition of "ground" is very tricky for you. Take great care, as you would in any system, that it is impossible for non-skilled staff to access live parts, and you should be OK

Steve
v.duong (author)  steveastrouk5 years ago
Thank you!
Don't forget to mark the Best Answer for future reference !
Good luck with it.
+1.
mitchiko5 years ago
Steve,

Since the beginning of this you are really great on this high five!!! Thanks for continues answer for people who's in need of an experts advise.

Kudos
Let me see the manual for the controller.

Steve
v.duong (author)  steveastrouk5 years ago
http://www.morningstarcorp.com/en/support/library/TSMPPT.IOM.EN.04.pdf

Yessir, and thanks!