Will this mixed solar panel configuration work

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John Frame asked Oct 10, '21

Will this mixed solar panel configuration work

I run a facebook group dedicated to teaching solar. Typically i advice against mixing solar panels because most of the time the efficiency losses are to high. So i will advice multiple charge controllers.

However this diagram was posted on my Facebook group. (This is NOT my design).
If you follow the math to it’s conclusion I get 98.44% efficiency.
However if you look closely at the diagram you will see he has mixed configuration creating sort of a 2P/2S/2P configuration.

My question is will this work. He has basically done one parallel string (2P) and then a series/parallel string (2S/2P). Then taken all that and put those in parallel as well.

Will this work? Theoretically the math comes out but can the Smartsolar 150/70 understand what is happening here and look at it as just a 2P config or will it freak out?

(THE MATH IN THE DIAGRAM IS NOT MY MATH IT IS THE ORIGINAL POSTERS MATH. I did my own math)

Thanks for your help.
Guy Stewart, would you have any thoughts on this?

@Guy Stewart (Victron Community Manager)

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Answer 1 · 2021-10-10T17:37:41Z

Alexandra answered · Oct 10, 2021 at 05:37 PM

@Off Gridin It

Controversial topic.

Yes, the string VOC and amps are very similar so would "work", not the way is has been calculated though. Loss of efficiency in the wiring and y connectors and a couple of other factors would being it down from the pefect paper maths.

Would the charge controller be confused? No volt amps are its only concern. It retracks if it cant get good yelids at each volt amp test. Can work it right down to a few volts above battery voltage.

And I agree with you, I would advise different charge controllers, two smaller (150/35A or three 100/20A) ones would be better and way more effective and pretty much the same cost (at least here where we are).

If you try use the mppt calc page with the panel string info, no models from Victron are recommended with the strings programmed in, that speaks louder than words. One mppt for vastly different panels is just not good practice.

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