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racerke600 avatar image
racerke600 asked

75/15 and 2x 120W panels, confused series or parallel

I have two 120 panels mounted to the roof of my california, and have a victron 75/15.
The vendor supllied two Y connectors to connect the panels in parallel.

But i'm maybe thinking of connecting them in series, this will reduce the clutter on the roof with the bulky Y connectors.

I already used the victron calculator and it seems that both would work.

However it says something about the max. number of solar cells being 108 for a 12V system.
This means that victron uses 36 cells panels for it's calculations?

So the main question is, can I wire the panels in series?
This would mean 144 cells?

My panels have these specs:

Generatorleistung wp 120 Wp
Solarmodul - Zellentyp monokristalline Solarzellen
Solarmodul - Anzahl Zellen 72
Systemspannung 12 V
Zellenwirkungsgrad 18.43 %
Modulspannung (VMP) 20 V
max. Strom (IMP) 6 A
Leerlaufspannung (VOC) 24 V
Kurzschlussstrom (ISC) 6,48 A
Max. Systemspannung 200 V/DC
battery charging
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1 Answer
wkirby avatar image
wkirby answered ·

Those specifications say that VOC is 24V, so two in series would make 48V.
The series configuration would be perfect for your 75V MPPT, in fact it would be better to use a series configuration instead of parallel.

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racerke600 avatar image racerke600 commented ·
Indeed with the VOC of 24V it seems possible. But I don't understand the limitation of the 72 cells? How does fit in the calculations?
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snoobler avatar image snoobler racerke600 commented ·

72 cells in series.


"Split-cell" or "half-cut" panels are like two panels in parallel together in the same frame. These are typically characterized by visually having an upper and lower half with the leads in the middle of the panel:


1646058173984.png

So while it may have 72 total cells in it, it's actually 2X 36 cell panels in parallel.



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1646058173984.png (20.0 KiB)

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