Mixing solar panels

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josefk asked Dec 17, '19

Mixing solar panels

Can mixing different panels damage MPPT controller or panels? I already have BlueSolar 150/85 MC4 MPPT and 2 x 300W Amerisolar panels. Those two panels will be fixed on the roof of my van and there's no more room because of the roof vents. So I was thinking if I could make a foldable panel set which would be easy to store and use when possible. Panels connected into Mppt's PV connectors would be like:

1) 300W mono panel, Voc 38,8V, Isc 9,88A, Vmp 31,7V, Imp 9,47A.

2) 300W mono panel, Voc 38,8V, Isc 9,88A, Vmp 31,7V, Imp 9,47A.

3) 4 x 90W poly panels, Voc 23V, Isc 5,07A. 2 in series and 2 in parallel.

I know it's not generally recommended but fitting third big panel anywhere would be really difficult (would be cheaper though).

MPPT Controllers

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Modifications Space

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Answer 1 · 2019-12-17T20:56:40Z

wkirby answered · Dec 17, 2019 at 08:56 PM

The specifications of third set that you propose are too far off from your main two panels. If the maximum power point of the two 300W panels is above 23V at any particular time, then the third set will not have any effect.
You'd be better off putting the third set on a separate controller, but then that also depends upon your battery Voltage. The third set would be OK witha 12V battery but not with a 24V battery.

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Answer 2 · 2019-12-17T23:37:04Z

Tom answered · Dec 17, 2019 at 11:37 PM

You should employ two controlers. I do not see why your 90 watt panels in a 2s 2p configuration would not charge a 24 volt battery. You would have 46 volts at 2s.

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Answer 3 · 2019-12-18T10:06:14Z

josefk answered · Dec 18, 2019 at 10:06 AM

Thank you for the answers! I think I have to put third panel on the roof on top the vent and maybe build a tilting rack with linear actuators or smth. Set of small panels with a new mppt would be a bit too pricey.

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