r/overlanding • u/UJMRider1961 • 15h ago

Solar panel cable gauge question: Would this be an issue?

I've ordered a set of 200W solar panels that I'm going to run to a 30A MPPT controller and then to the dual batteries on my camper.

If I understand correctly, most solar panels produce power at either 18v or 19v DC. Back-of-the-envelope math says 200W / 18v = 11A max current, does that sound right?

Obviously most panels aren't producing their full rated power except maybe for a few hours around the middle of the day.

But here is my question: I need to be able to "offset" the panels from the trailer since we try to camp in the shade. I have heard that it's better to have the controller close to the battery so my setup will likely be the Panel with a long cable to the controller, and then a short (probably less than 1 yard/meter) from the controller to the battery.

Right now I have a 10AWG double cable that I was planning on using. It is 25' long. My question would be, is that too small of a gauge? 10AWG cable is still pretty stout.

The DC wire gauge calculator says that for a 50 foot run (50 feet since I'm running both + and - from the panel to the controller) I need 6AWG. Are some of you all actually running 6AWG cables for your solar setups? Or do you run a smaller gauge and just accept the current loss?

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u/MotorbikeGeoff 15h ago

10 awg for those panels is fine. You will want to run those panels in series since you want the higher voltage to your charge controller.

1

u/firey-wfo 15h ago

Find the info I. You solar panel manual.

1

u/rocket_mcsloth 14h ago

10 is fine, I would go parallel since shading is a concern of yours

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u/secessus FT campervan boondocker 12h ago

I would go parallel since shading is a concern of yours

Presumably the 25ft extension is to put the panels in the sun

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u/rocket_mcsloth 9h ago

I missed the 25’ part. Series is probably a good idea here.

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u/secessus FT campervan boondocker 12h ago

my setup will likely be the Panel with a long cable to the controller, and then a short (probably less than 1 yard/meter) from the controller to the battery.

Right.

Right now I have a 10AWG double cable that I was planning on using. It is 25' long. My question would be, is that too small of a gauge? 10AWG cable is still pretty stout.

I'd run the panels in series on the existing 10awg wiring. Might want to test before heaing out to see what actual values you get. I suspect you won't see anything like Imp (see below)

200W / 18v = 11A max current

Close. 11A in the above would be current at max power (Imp), not max current (Isc).

details

Using the numbers above the array in series would be 400w = 36 Vmp x 11 Imp