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diy solar

Random Help with solar wire sizing !

Benihanas

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Joined
Feb 20, 2021
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I am sitting here tonight and just now realizing I may have made a horrible mistake.....

I have 8, 100watt solar panels installed on the roof of my rv. two separate 400 watt 12 volt (18.1 optimal voltage) arrays. I have Will's exact 400watt with alternator charging kit plus 400watts essentially.

here's where I believe an issue may be present; I am using about a 35 foot run of 10awg solar wire from both 400 watt arrays.... this isn't close to the size it needs to be to be either safe or efficient is it? im so confused I am getting all types of answers online with the calculators. renogy's site says I may need 2 awg solar wire! I didn't even know they made it that size. my rv is not big but I am running the cables down through a vent on the back of the rv , then around the kitchen, and under the floor.... they are buried and I have a longer run than I should really have I think ( this is literally the only long run in the rv)... do I need to reconfigure my setup?

my MPPTs that im using are the DCDCS50 and the rover 40 amp by renogy ... I could put all of the panels on the rover 40 in theory... it can handle 100 volts , or I could even connect the two arrays in series and wire them that way... id love someones insight on this and hopefully im freaking out for no reason , not sure what I was thinking when I bought10 awg pv wire It was about a year ago that I built this and I feel ive learned a lot since then and just using a system and understanding electrical wiring .. thanks in advance ! cheers!
 
4P = assuming about 24A Isc.

You have a pair of 10awg conductors for the DC-DC array AND a pair of 10awg conductors for the Rover array?

If so, each pair of wires should handle 30awg; however, you will have excessive voltage drop of about 9.3% @ 18V, 24A and 35' of 10awg.


For a roof mounted array on an RV, I wouldn't consider this a major issue. If you have the option, you could run another pair of conductors to the DC-DC array, i.e., you'd basically have a 2P+2P array, with each 2P having it's own pair of 10awg. You would then parallel them right before the DC-DC. In that case, each 2P portion would only have a voltage drop of 4.7%.

You could solve the problem on the rover array by 2S2P:


2.3% drop
 
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