Solar Panel Chassis Grounding

[MikeD]

I'm in the process of adding solar panels to my 2720 (battery on the tongue), and have a grounding question. From what I read (including the info in the installation guides for my panels and charge controller), it appears that I need to run a new wire (bare copper, 8 to 10 guage) from the chassis to the charge controller and the frame of the solar panels. My understanding is that this is an electical saftey issue of the charge controller (even though the negative is bonded to the chassis at seveal points), and also one for the panels (possibility of lighting strike, ...).

Is this what others have done ? This would mean that I need to run a three wire cable to the panels rather than the 2-wire cable I had planned upon. No problem - safety is paramount, but I wonder what other's have done.

Thanks, MikeD

p.s. I guess that my confusion is that there is no real Earth ground (only a floating chassis gound) on a trailer unless you are plugged into shore power. Earth grounding in a trailer confuses me.

[RockyMtnRay]

Originally Posted by MikeD

I'm in the process of adding solar panels to my 2720 (battery on the tongue), and have a grounding question. From what I read (including the info in the installation guides for my panels and charge controller), it appears that I need to run a new wire (bare copper, 8 to 10 guage) from the chassis to the charge controller and the frame of the solar panels. My understanding is that this is an electical saftey issue of the charge controller (even though the negative is bonded to the chassis at seveal points), and also one for the panels (possibility of lighting strike, ...).

Is this what others have done ? This would mean that I need to run a three wire cable to the panels rather than the 2-wire cable I had planned upon. No problem - safety is paramount, but I wonder what other's have done.

Thanks, MikeD

p.s. I guess that my confusion is that there is no real Earth ground (only a floating chassis gound) on a trailer unless you are plugged into shore power. Earth grounding in a trailer confuses me.

I'm running a 2 wire cable to the panels from the controller (one is the ground) and see no need whatsoever for a 3 wire setup. My controller doesn't even have a 3rd connection point...just two wires to the panels and two wires to the battery. When the controller wants to cut off solar input to battery, it simply shorts the panel output to panel ground! This may be a bit shocking but the amount of current that can come from a given panel array is limited by the number of photons falling on the panel and that panel's ability to convert those photons into moving electrons. The panel, in other words, has a maximum current even if directly shorted to ground.

Keep in mind that we're talking solar generated (see above) 12 volt DC power here...there's a plus and a minus, a definite limit to max current, and no need to get fancy. If the panels were to be hit by lightning, the bolt would immediately go through the microscopic layer of adhesive/paint between the panel frames and the trailer's skin. From the trailer skin, it would go from the frame through the jacks to ground.

Maybe if the panels/controller were being used in a residential installation (e.g. a remote cabin) with panels mounted on some pedastal, there might be other considerations for dissipation of lightning bolts. But for use on a TM, I strongly recommend following the K.I.S.S. principal.

A final thought...even if you wanted to run a bare copper 8 gauge conductor from the panels to the controller, you really couldn't do it well unless you used a braided or stranded conductor. The reason is that conductor has to readily twist and bend (if the panels are on the roof) so the shells can fold down.

[MikeD]

Ray,

Thanks - this was my thinking also. I would understand grounding the panel frame if I had access to a real Earth Ground. I'll skip worrying about it.

MikeD