question

heavymetalmountainman avatar image
heavymetalmountainman asked

Is this still doable?

During my order of equipment I managed to get a great deal on 12 panels slightly larger than the ones I was planning on buying. I had already ordered 3 SmartSolar MPPT 100/20 48V and going to do a 2S2P per controller. The concern is that the CC is rated for 100v/20a max, the Voc per panel is 40.4v so the max incoming voltage per CC will not be greater than 80.8v which is within parameters but the Isc per panel is 10.3a putting my max incoming amperage per CC at 20.6a which is a hair over the rated amount. Am I now stuck having to get new CC's to handle these panels or is this less than 1 amp overage not something to worry about?

MPPT Controllers
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2 Answers
wkirby avatar image
wkirby answered ·

It will be dificult to say for sure once you go outside of the specified limits.
Similar to if you were to drive over the speed limit, you should then expect to get a ticket. You might not get a ticket, but you shouldn't be surprised if you do.

Those ratings are usually at 25°C module temperature. As the temperature of the modules rises above 25°C, the Isc will be even higher.

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nigelfxs avatar image
nigelfxs answered ·

Hi @HeavyMetalMountainMan

Although I an not 100% certain, it is very likely that the comments on the PV Short-circuit current rating, in the following link also apply to the MPPT 100/20-48V. See https://community.victronenergy.com/questions/70621/smartsolar-rs-450100-spec-sheet-confusion.html

However a PV string that is connected in correct polarity CAN exceed 20A without damaging the MPPT. So this PV input current limit is less strict than the PV input voltage limit.

So you should be okay, as long as you don't wire things backwards ;-)

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