question

goboatingnow avatar image
goboatingnow asked

Solar panel config on a boat

I know versions of this type question have be asked before , so bear with me


The boat has 2x SPM100-12/3a panels , no MPPT, I was going to upgrade to 2x SPM0417512 , 170W , series 4a panels


However I have space for all 4 panels , I was thinking of wiring each 100W in series with a 170 W , and paralleling it to the other 100+170W set of panels , using a single 100/50 Smart solar controller


is this a feasible solution , in general I dont have a shading issue , typically at anchor with the sails down as the panels are mounted above the Bimini .clearly I could put each series string on a separate mppt controller, but costs mount


thanks in advance


DAve

MPPT ControllersSolar Panelsolar sizing
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1 Answer
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JohnC answered ·

Hi @goboatingnow

Best to keep your panels the same in each string. So run 2x 100W in one, and 2x 170W in the other. What you've proposed may limit all panels to 100W.

Then parallel the strings. The Amps (W) will add fine then.

A 100/50 would work, and those panels should be fairly well matched with their tracking V. But if you wanted to do it by-the-book with 2x mppt's then it won't cost much more, maybe even less if you chose (say) a 75/15 and a 100/20. The 100/20 a little underspec, but you may never see that realized in practice.

Fair winds..

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