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PWM Controller Recommendation for Mismatched Panel System?

gcp

Going nomadic.
Joined
Sep 1, 2021
Messages
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Hello! I am outfitting a tiny camper with solar panels, a 170 Ah 12v lithium battery, and a 2000w inverter charger so I can live/work off the grid for a while. Due to space constraints and the presence of other equipment on the roof, I'm attempting to maximize power generation by using a parallel system of mismatched panels from Newpowa. The panels are all the same Voltage (16.77), but different Amps. My MPPT charge controller isn't going to work with this system, so I'm looking for recommendations for a PWM charge controller to use with this system. Thank you!

Some more details:

I have four solar panels from Newpowa (specs sheets also attached):

(2x) 210w Mono Panels
– 16.77 Vmp
– 12.48 Imp
– 19.83 Voc

(2x) 160w Mono Panels
– 16.77 Vmp
– 9.3 Imp
– 19.83 Voc

If my parallel system calculations are correct, under ideal circumstances this system will produce:
16.77 Volts
43.56 Amps

I was intending to use a Renogy Rover 60v 150v MPPT Charge Controller and a 170Ah 12v Lithium battery and some big fat wires between the roof and controller. I just realized however, that this parallel setup won't create enough voltage to activate the MPPT charge controller in less than ideal sunlight conditions, as MPPT needs the panels to produce a few volts more than the battery's voltage in order to activate.

So, here I am asking for PWM charge controller recommendations for this setup. (Or, for someone to tell me that I'm better off cutting my losses, trying to return to sell these items, and get a matched system that generates less power, but is a bit simpler overall.)

Thank you very much!
 

Attachments

  • NPA210S-12H.pdf
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  • NPA160S-12H.pdf
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  • Rooftop Plan - Solar.pdf
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I might consider splitting it into two arrays of two matched panels in series and using two smaller MPPTs. That should yield more power than using a big PWM. Another benefit is two 30A Rovers are cheaper than one 60A and give you some redundancy.

And welcome to the forums!
 
I was intending to use a Renogy Rover 60v 150v MPPT Charge Controller and a 170Ah 12v Lithium battery and some big fat wires between the roof and controller. I just realized however, that this parallel setup won't create enough voltage to activate the MPPT charge controller in less than ideal sunlight conditions, as MPPT needs the panels to produce a few volts more than the battery's voltage in order to activate.
I don't think that's going to be a problem. I have a very similar setup on my RV to what you're proposing - A pair of 175 watt panels in parallel with a single 100 watt panel, all from the same manufacturer (Newpowa IIRC) with the same Vmp

I'm using a Tracer 4210AN 40 amp MPPT controller and I get good production from early dawn to dusk. I would stick with MPPT over PWM in this case . . . . but maybe the 'experts' will tell me I'm wrong?? All I know is, mine works fine all the time

Don
 
series/parallel combining is by far the best option imho.

Just create 2 strings:

2x 210 in series
parallel with
2x 160 in series.

That would give you approx 33Vmp / 22A of PV capacity.

When running all in parallel, the amperage would be doubled, thus requiring thicker wires (harder to handle). Also, the MPPT when running at 33V PV input will give a better efficiency compared to running 16V into a PWM controller.

For the controller, I personally would prefer Epever (if you have limited budget) or Victron.
If you have the space, it might be an option to go for 2 30A controllers instead of 1 60A version. That would give you some redundancy if one controller somehow fails.
With the 2x210W in series you will loose some available PV, since 420W is slightly more, but since the panels are flat mounted most likely, I doubt if they ever will do the maximum rated output (Since thats usually only achieved at a proper angle)

The Epever Tracer 6420AN is a nice MPPT option, I personally prefer Epever over Renogy.

The Victron 100/30 is another great option, with easier software and settings (App/bluetooth). And when serie-connecting 2 panels you don't have any issues with the required start voltage for the MPPT (if I remember correctly, Vbattery + 5V)
 
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My Victron MPPT 100/30 won't turn on unless the panel voltage is more than 4 volts over battery voltage. To charge at 14.4v, the controller needs 18 volts or so.

Here's a very detailed article about mixing panels, and what happens.

 
I take back what I said about the Epever 60A Viewstar, as you cannot adjust the float voltage to suit a lithium battery (missed that the first time I read the post).

I would think outside the box if you need to in order to mount a couple of programmable MPPTs (for each pair of panels). Victron units have a pretty small form factor
 
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