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wjohnston avatar image
wjohnston asked

Over paneled math question

I have the SmartSolar 100/30. I have 9x 100watt poly panels installed atop a travel trailer. 3 at a 5 degree rake to driver's side, 3 straight up, 3 at 5 degree rake to passenger side. They are wired in 3 series sets. Poc is 18.2v each and 5.49a each. Each series set is the. 54.6v at 5.49a and the parallel combined is 54.6v at 16.47a. I understand if I were to get near perfect sun that I would be generating more current than the charger can use. Am I risking damage to the controller? The peak voltage and current appear to be under the max of the controller, but, I feel I am missing something.

MPPT SmartSolar
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2 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

You will not damage the MPPT but you waste a lot of power (in a 12V system). In a 24V system the loss is not so big.

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Vance Mitchell avatar image
Vance Mitchell answered ·

I am assuming you are using a 12v battery system.

If so the maximum watts into your batteries will be approximately 440 (14.8 x 30).

The bit you are missing is that the '30' is referring to the output Amps not the input Amps.

You are well under the maximum panel voltage so that shouldn't be an issue but the amps might be. It is common to oversize an array by 10-20% but you are currently at over 200% of the capacity. You should be fine with two of your arrays connected to the controller (30% over) but I would look at adding another controller (100/20 ideally but a 75/15 or 100/15 would allow up to 220W ) for the 3rd series set.

For a system with strings on different orientations it is normally recommended to use a separate controller for each string.

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wjohnston avatar image wjohnston commented ·

The 3 series sets are identical, each has 1 panel rake driver, straight up, and rake passenger. The original system was just 6 panels but cloudy days were eating my lunch. The added panels are really for shaded or cloudy days. Eventually I will put in a larger controller but was hoping to save that expense until later. Thanks for the answer!

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