Victron 100/30 MPPT voltage for 24v battery

[caki]

Hi Folks:
I got the Victron MPPT 100/30 and the 24v EG4 LifePower battery. I have 3 Solar Panels Q.PLUS L-G4.2 330 (datasheet attached). I'm trying to figure out the best configuration for the voltage and the way to connect the solar panels. The options I see are:
1 - Connect them all in parallel. The Voc is 46.5 and Vmpp is 37. The battery charging voltage is 29V. While this is close I'm assuming this should be fine for the MPPT to work.
2 - Add a fourth panel and use then into 2S2P (2 serial and two parallel). However I would be going over the solar capacity of the MPPT of 880 watts by a large margin as 4 panels would be 1320 watts.
3 - Replace the charge controller with a Victron MPPT 150 / 35 use them all in series. More opportunity for shading and power loss.
I'm leaning towards 1, but would like to check on the wisdom of the group.
Thanks

 

[sunshine_eggo]

1. This is the only option: 1SXP.
2. 2S would be too close to 100V for safety, thus 1SXP is the only choice.
3. 3S would be too close to 150V for safety, thus 1SXP or 2SYP is the only choice on this controller.

Panel voltage increases as they get cold. 2S 46.55Voc panels would blow the 100Voc limit at around freezing. Same for 3S @ 150Voc.

If shading or partial shading is a concern, more parallel, less serial is the better solution.

Panels flat on a roof perform horribly in winter. Typical for them to deliver about 40% of their rated in the best conditions.

 

[HOU_Castle]

Hi Folks:
I got the Victron MPPT 100/30 and the 24v EG4 LifePower battery. I have 3 Solar Panels Q.PLUS L-G4.2 330 (datasheet attached). I'm trying to figure out the best configuration for the voltage and the way to connect the solar panels. The options I see are:
1 - Connect them all in parallel. The Voc is 46.5 and Vmpp is 37. The battery charging voltage is 29V. While this is close I'm assuming this should be fine for the MPPT to work.
2 - Add a fourth panel and use then into 2S2P (2 serial and two parallel). However I would be going over the solar capacity of the MPPT of 880 watts by a large margin as 4 panels would be 1320 watts.
3 - Replace the charge controller with a Victron MPPT 150 / 35 use them all in series. More opportunity for shading and power loss.
I'm leaning towards 1, but would like to check on the wisdom of the group.
ThanksView attachment 77704

My conservative opinion: no matter how you do it (series/parallel) with Victron mppt 100/30, you can only use two 330W panels.
You need mppt 100/50 or mppt 150/35 to utilize all of your 3 panels.

 

[sunshine_eggo]

My conservative opinion: no matter how you do it (series/parallel) with Victron mppt 100/30, you can only use two 330W panels.
You need mppt 100/50 or mppt 150/35 to utilize all of your 3 panels.

Given that he will almost never get peak current from 990W flat on an RV roof, and the Victron is rated for 880W, and they routinely recommend over-paneling up to 30% over rated provided Voc and PV input current limits are observed, 100/30 will work fine.

 

[HOU_Castle]

Given that he will almost never get peak current from 990W flat on an RV roof, and the Victron is rated for 880W, and they routinely recommend over-paneling up to 30% over rated provided Voc and PV input current limits are observed, 100/30 will work fine.

He does not mind risking on his Victron; he can proceed.

 

[Dzl]

It is my understanding that Victron permits overpaneling (in terms of Watts) as long as the input voltage and input current spec's are not exceeded.
You can read more here:

Matching solar modules to MPPT charge controllers - Victron Energy

Life used to be so simple; in a 12V battery system you took a ‘12V’ solar module, watched carefully that the maximum PV current would not exceed the charge controller maximum current and the system would work. Unfortunately due to the fact, that with PWM controllers the PV module is not feeding...

www.victronenergy.com

 

[sunshine_eggo]

He does not mind risking on his Victron; he can proceed.

That's absurd. He's not risking it. It's literally within Victron's specifications:



It's "Nominal" power. Not Max.

He's under 100Voc
He's under 35A max PV input current

Here's what Victron says about overpaneling:

Matching solar modules to MPPT charge controllers - Victron Energy

Life used to be so simple; in a 12V battery system you took a ‘12V’ solar module, watched carefully that the maximum PV current would not exceed the charge controller maximum current and the system would work. Unfortunately due to the fact, that with PWM controllers the PV module is not feeding...

www.victronenergy.com

It's fine to be conservative. Fearmongering on baseless claims doesn't do anyone any good.

 

[caki]

Thanks guys for the discussion. I appreciate your time and experience. I'll move ahead with option one.

 

[caki]

For further reference I found this post that seems to settle the issue, with reference to several controller models: https://diysolarforum.com/resources/overview-of-over-paneling-an-mppt-controller.229/
For my specific case, it seems to be fine.

 

[Paul_R]

If shading or partial shading is a concern, more parallel, less serial is the better solution.

Panels flat on a roof perform horribly in winter. Typical for them to deliver about 40% of their rated in the best conditions.

Very good points here. I personally would not have any series connected panels on a camper and all my panels tilt.