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How to wire 12V solar panels for renogy 50A DC-DC + MPPT charger?

Pmsem

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Jun 15, 2022
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Hi all,

The renogy manual is unclear. It states that the max. solar input voltage is 25V. I have 5x100W and 1x50W panels. I was planning on wiring every other panel in series (thus yielding 3x 24V panels) and having these 3 panels go to the charger. This would keep the current below the lot of 25A and would mean I could use smaller cables. However, the voltage limit on the charger is 25V. I am aware that when solar panels are in the sum the output voltage increases. Will I be ok to wire my panels as described? Many thanks in advance!
 
For any kind of controller this strategy is completely wrong. All solar strings need to be the same voltage. Please state the exact model of controller you are working with? As far as I know, Renogy does NOT make an MPPT controller with a 50V limit.
 
Hi, yes they would all be the same voltage (24V).

No they won't.

12V, 24V, etc. are NOMINAL voltages - an old term intended to identify panels suitable for a given system voltage. In reality, those panels will actually operate between 17 and 22V.

Why would I need to out them in parallel rather than series?

It's the following controller:

Because that's what that unit is designed for. Note that your panels likely have a Voc value of 20-22V. THAT is the number that must not exceed 25V.

2 * 20 = 40V

40V > 25V
 
Hi, thanks for that. Wasn't aware of what the Voc meant until a few mins ago. I'll be wiring them all in parallel.

With regards the 50W panel. The 100W panels are all from renogy, as is the 50W panel. Is there any reason I shouldn't use the smaller panel?

Cheers
 
Hi, thanks for that. Wasn't aware of what the Voc meant until a few mins ago. I'll be wiring them all in parallel.

With regards the 50W panel. The 100W panels are all from renogy, as is the 50W panel. Is there any reason I shouldn't use the smaller panel?

Cheers
If the Vmp and Voc of the 50w panel are lower than the others it will bring the other panels down to match it and lower your total output
 
If the Vmp and Voc of the 50w panel are lower than the others it will bring the other panels down to match it and lower your total output

This is not true as an absolute. The MPPT will still find the max power point as long as there is significant overlap between the Vmp to Voc range.

When talking about panels in series, it is absolutely true that all panels will operate at the lowest current panel in the string.
 
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