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Series panels to parallel battery

tmcgann

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Apr 22, 2022
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First Van set up. Two 210 Watt solar panels. 40amp controller and one 200ah battery. Can I run the panels series having 24 volts go into controller with just having the one 12 volt battery? Any benefits to running series on this small system with still having battery at 12v? And is 40amp needed?
 
Can I run the panels series having 24 volts go into controller with just having the one 12 volt battery?
Which charge controller? What is max input voltage?

Same for panels... what is the panel Voc spec?

(2x 210W) / 14V charging = 30A so 40A SCC seems nicely sized.
 
Thank you for response.

VOC panels are 19.83 per panel

EPEVER MPPT Charge Controller 40A 12V/24V​


Main questions is could I run panels in series into this charge controller and still have just a 12v battery?
 
That depends on the max VOC of the charge controller. But probably, yes.
 
Main questions is could I run panels in series into this charge controller and still have just a 12v battery?
You could have a 500V array into a 12V battery if the SCC can handle that many input volts. That's what an MPPT does, it takes what the panels produce and turns it into charge voltage and current.

With panel Voc 19.8, x 2, your SCC would need to accept 50V input due to temp compensated voltage.
 
Great explanation. I watched a ton of videos, and I may have missed it, but I never see that directly discussed. Maybe my amateur ears are not getting the lingo when it's explained. Just would be easier to run the two panels series. Not sure if I will get any benefit, but with this system and for what it will be powering, I should be ok. I will verify the Charge controller to make sure it can accept the 50v.
 
Not sure if I will get any benefit,
Generally having a higher array voltage, so your SCC receives its minimum start charging voltage, to allow charging earlier in the day, later in the afternoon and cloudy days. Min voltage is usually battery voltage +5V.

Your panels probably have a Vmp that barely makes startup voltage so a big benefit.
 
VOC panels are 19.83 per panel

EPEVER MPPT Charge Controller 40A 12V/24V​



You didn't specifiy the model but AFAIK there is no EpEver 40A with an input limit lower than 100v. The manual will tell you for sure.

The MPPT startup for these controllers is Vbatt+2v, so even parallel should work fine. I'd try it both ways to see what you think.


And is 40amp needed?

<shrug> A 30A would also be fine unless it was an area with lots of excellent sun. Some of the 30A may have a lower limit (60v IIRC).
 
"VOC panels are 19.83 per panel"
What is the Vmp?
Most of the so called '12V panel' has Voc around 20 ~ 22V, Vmp around 17 ~ 18V.
 
VMP is 17
Series will definitely help. If you are charging at 14V, that’s just vbatt+3.
fratermus says these need vbatt+2 (which sound low to me) so it will take good sun to charge.
I read something the other day that indicated a particular unit needed vbatt+5 to start but could continue at vbat+1 or 2.
 
My panels are still sitting in the box. I can return them. Found 200 watt panels with VOC 24 and VMP 20.17 for around the same price. Would that be a major upgrade?
 
Well, after reading up and from what you guys have explained, it is a major upgrade so I believe I will make the swap.
 
Found 200 watt panels with VOC 24 and VMP 20.17 for around the same price. Would that be a major upgrade?
Going from 2x 210W panels to 2x 200W panels sounds like a downgrade of 20W.

You are in great shape with those 2 panels in series. That’s a good 34Vmp.
No need to change.
 
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