Panel to Solar Controller Wire Size
As some of you already know, I'm piecing together a solar system. Controller is a Morningstar 45A PWM. Panels will be two 12V 150W wired in parallel. I'm going to be using a combiner box on the roof, ...
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mena661 wrote:BFL13 wrote:X2 thanks for that explanation.
Salvo, thanks for the explanation.smkettner wrote:Hmmm. The #10 is cheap enough and I might be able to use it for my next solar project. I've only done some preliminary planning on that. It's not RV related though.
I would love to see an actual comparison of #10 vs. #4 on this set up.
I think I follow Salvo's explanation but you always still have to ask, "Percentage of what?" and if that "matters" to you in real life.
In real life it does not matter to me if Isc falls from 8.2 to even 7.9a as I have seen, before battery voltage reaches say, 14.6v. I would not rush out and get fatter wire because of that. Nor do I see any impact from temperature rise of the panel with the PWM.
I see on a hot day, that Voc is down to 20.3 out of rated 21.9 (I posted about my "missing volt" a couple years ago) but I also see that I am still getting Isc of 8.2a or even 8.3. I note in the panel specs that Isc goes up with temperature, not down. So even if I have lost some voltage overhead I make up some/all of that in amps to the battery.
It works out ok for me where and when I camp using solar. It may not work out right for anybody else. What I am worried about till I get to try it, is my new MPPT set-up. I have seen how the Voc on the 230w panel drops with heat, but I don't know how badly that will affect amps to the battery. It might be that it will get fewer amps than with 230w of PWM--in which case I will be seriously annoyed!
