question

4ncar avatar image
4ncar asked

Not getting close to max Wattage from Solar Panels

I have a 75/15 SC and 4 @ 100 watts of PV panels in parallel (3 fixed, 1 suitcase). I understand that the controller will limit amps, but in full ARG Texas sun(as full as February will give) I have yet to see any thing over 220 watts coming from all 4 (and even 3) panels. I am getting 20+ volts from each panel, and from the array. This condition prevails even when less then 100% SOC. What is particularly curious is that the SC “meter” will show 200+ but it will be close to the end of the range( as if 200 is the maximum the gauge will reflect).

What am

I missing?

MPPT ControllersSolar Panel
2 |3000
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1 Answer
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wkirby answered ·

You did not mention what your battery Voltage is.
I'll assume that it's a 12V battery? If so then 220W maximum sounds about right to me.
You see, the charge controller can charge with a maximum current of 15A, so power is current multiplied by Voltage. If you battery is approaching full, then it would be around 14.5V, so 14.5 x 15 = 217.5W.

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4ncar avatar image 4ncar commented ·

Yes, 12v. I understand, simple math, so, to best utilize the solar array, I need to increase the SC capabilities?

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wkirby avatar image wkirby ♦♦ 4ncar commented ·
Yes, you basically need a bigger MPPT controller or more MPPT controllers.

Maybe a 100/20 for your fixed panels which is a little bit under the full capacity of your array with no headroom, ideally a 100/30 would cover those three with spare capacity.
Best not to connect the folding panel to the same array as the fixed ones because mixing panels like that is not really a good idea. So keep your 75/15 for the folding panel on its own.

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4ncar avatar image 4ncar wkirby ♦♦ commented ·
Awesome, thanks!
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