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ziigatron avatar image
ziigatron asked

2 x 170watt 12v panels in series. OK with MPPT 75 15?

Hi, I have 2 x 12v 170watt panels wired in series I believe. (cant exactly remember the configuration as they came in a complete kit with cheaper PWM. They've been there a while.)

The output of the array is currently 22V in todays conditions, measured at the PV input of the MPPT 75 15

I think they are in series, because of the voltage measured from the array is effectively double the individual 12v panels rating.

Unless 12v panels actually create the higher voltage as standard individually?

Am I right in thinking that the array is producing a max of 340w / 22v = 15.45amps?

And on that basis the MPPT 75v 15A is going to be able to efficiently manage the charge current to three 12v leisure batteries wired in parallel. (So a 12V battery bank with higher amp hours.)

Seems like the MPPT 75v 15A should be fine, or have I made a mistake somewhere?

Thanks for your help.






MPPT Controllers
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Michelle Konzack avatar image Michelle Konzack commented ·
Since you have a PWM in a Camper with 12V System, the panels are parallel because there are no 170Wp panels with 11V, but there are some things:


1) The 75/15 mean, maximum panel voltage 75W with maximum 15A output.


2) The 170Wp Modules have usually around 18-22V which mean you can put them in series (36-44V) at the SmartSolar MPPT 75/15.


3) The SmartSolar MPPT 75/15 support only 220W in a 12V System, hence a bigger 20A (330Wp) or 30A (440Wp) is more suitable


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kevgermany answered ·

Guessing. Yes.

Assuming you have a Bluetooth MPPT, connect with Victron connect. This will tell you the actual values for panel and battery.

In terms of series/parallel, you really have to check the connections, a 12V panel will make well over 12V.

There should be a label on the back of the panel giving its specifications. Voc from there will help a lot.

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regman54 avatar image
regman54 answered ·

If your previous charge controller was a PMW and the panels were wired correctly they should be wired in parallel, not series. As mentioned you need to use the labels on the back of the panels to know the appropriate sized charge controller to use. You can't go by whatever the days conditions are/were. Perhaps these links will help sort things out: (I am not affiliated in way with Explorist Life)

https://explorist.life/solar-panels-series-vs-parallel/

https://explorist.life/solar-charge-controller-calculator/

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