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24 Volt Panels charging 12 volt battery MPPT

Glenn.Hurley

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Nov 16, 2021
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I tried to find a thread on this but no luck.

I have 2 BB 12 volt batteries in parallel in my RV.
I want to put up to 800 watts solar on my roof and charge with the 40AmTracer BN or the 40 Amp Rich Solar.
The pre wiring from the roof to the SSC is 10 AWG so max 35AMPs

If I go 12 volt in series to the MPPT I bump into the amp 35 amp limit of the wire, but voltage is good.
If I go 24 volt in series to the MPPT I bump the volt limits but the amps fit nicely.

My question is can I use 24 volt panels in series to the SCC and have it charge a 12 volt battery bank?
I only bump if all the panels are running full rated output.
 
go 2 panels in series. rich solar 40a has 100v pv limit so you should be fine with 2x 36 cell panels in series for ~ 60 - 70 Voc.
 
Yes 24 volt panels can charge a 12v battery. Multiple 24v panels in series can charge a 12v battery. Just make sure the Voc is 10% lower than the controller Vmax.

My 12v battery is charged every day with three panels in series for about 90 volts into the controller.

Best to list the controller make/model and the panel specifications for best answers.
 
MPPTPV WattsVoltAmp
EpEver Tracer BN 40520/104015040


Rich Solar 20 0 W PanelsWatts SCVolts SCAmps SC
200 Watts 24 volt 264.6845.405.83
200 Watts 12 volt 247.8624.3010.208.16

I understand the math and I think t says I need to run 2 pairs in 2S2P or 2P2S not sure which is better.
My main question is will the Solar Charge Controller take in 24 or 48 volts from panels and output it to the 12 volt battery bank in the rv?
 
MPPTPV WattsVoltAmp
EpEver Tracer BN 40520/104015040


Rich Solar 20 0 W PanelsWatts SCVolts SCAmps SC
200 Watts 24 volt 264.6845.405.83
200 Watts 12 volt 247.8624.3010.208.16

I understand the math and I think t says I need to run 2 pairs in 2S2P or 2P2S not sure which is better.
My main question is will the Solar Charge Controller take in 24 or 48 volts from panels and output it to the 12 volt battery bank in the rv?
Mppt converts the PV voltage to the battery voltage needs.
 
That i good news!

So I guess I can use 200w 24 volt panels in 2 pairs.
Any advantage to using 2P2S vs 2S 2P?
 
If the MPPT controller is capable of 2 panels in series input 24 v to MPPT and on the controller output step down charge 12 volt batteries ??

If so ,Is it best to bring the higher voltage to the MPPT

will my battery charge at a faster rate

Thanks
 
If the MPPT controller is capable of 2 panels in series input 24 v to MPPT and on the controller output step down charge 12 volt batteries ??

If so ,Is it best to bring the higher voltage to the MPPT

will my battery charge at a faster rate

Thanks
Yes, that is the advantage of MPPT controllers. They will boost the amperage and give you the best possable charging rate.
 
should have proof read my post

I have 2-175 watt panels on my boat Mainly to keep the beer cold I am on a , mooring

I currently have them wired in parallel. 12 volt

I can series tem to 24 volts .... bringing 24v to my MPPT load side out to battery bank 4-4d batteries
The 4d batteries are wired parrallel

The MPPT controller with step the voltage down to 12 volts to charge the house bank ??
The MPPT controller can detect that my system is 12 volt ?
 
should have proof read my post

I have 2-175 watt panels on my boat Mainly to keep the beer cold I am on a , mooring

I currently have them wired in parallel. 12 volt

I can series tem to 24 volts .... bringing 24v to my MPPT load side out to battery bank 4-4d batteries
The 4d batteries are wired parrallel

The MPPT controller with step the voltage down to 12 volts to charge the house bank ??
The MPPT controller can detect that my system is 12 volt ?
What is the make , model, and the spec of your MPPT?
Are you using it right now?
You should also start your own thread.
 
Last edited:
FYI
the picture of the MT50 is the same controller at 2 different times more sun

My Nav Station battery voltage reading is usually .5 or so off

I have the EPEVRS MPPT I see they offer a blue to adaptor
 
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