MPP Solar LV2424- configuration using 270W panels?

[madmax]

Anyone familiar with this unit, I could use some guidance. I ordered these panels from santan: (yes, the snail trails one!)
and I want to use this with a LV2424.

• Rated Power: 250W
• Open circuit voltage (VOC): 37.6 V
• Max power voltage (VMP): 30.3 V
• Short circuit current (ISC): 8.85 A
• Max power current: 8.27 A
• Power Tolerance 0/+3%
• Maximum system voltage: 600V (UL)

My thought was, have a 3S3P configuration. VOC is 112.8v, VMP is 90.9V, and max power would be 24.81A. , well within the MPP range.

Everything is good, except for the slight over wattage, of 2250w.

These are used panels, so I do expect some loss of performance. But lets assume they all test to their rated;

I know some setups allow for oversizing the array as compared to the charge controller; the controllers just can't use the extra power.

Honestly, I get less than 2 hrs of peak production anyways.

 

[FlyinBrian]

I have the same panels and lv244. I have 3s2p. So far on the best day I saw 1580watts. I was hoping to go with 4s2p but the voltage would be too high. I think. It looks like to be within all specs you can only go 3s2p. I think the wattage would over do it.

 

[FlyinBrian]

Here is my array.

 

[madmax]

I wrote to MPP solar (tw). they said I was GTG with a 3S3P! Overprovisioning is apparently quite common, where the solar watts are over what the system can handle at a peak, but it increases the duration of that peak. (i.e. instead of 1hr between 12-1 generating 2000w from 2000w of panels, you get 2000w of production between 11-2 from 2250W of panels, and also gain some watts before and after that peak.

Going to 4s is too high on the open voltage, and they specifically warned about not going over the 145.

 

[FlyinBrian]

I wouldn't trust it man. Like I said, with those panels they actually put out a little more than 250 watts in full sun each. But do as you think is right. Keep me posted. Thanks

 

[FlyinBrian]

This is 2s2p. Just over 1.03kw

 

[mrdavvv]

The overwattage shouldnt be a problem teorically, just watchout the VOC, more info: https://diysolarforum.com/threads/sizing-an-array-for-mpp-solar-lv2424.1395/post-57819

 

[namesgolden]

you're just a few steps ahead of me. I ordered 250w 60cell santan's and a mpp2424 and plan to mount them in a 2s5p array on the roof of a old FEMA trailer that I've gutted (rental land, want to be able to move array)

whats your current storage situation and loads? are you running a/c?

 

[FlyinBrian]

you're just a few steps ahead of me. I ordered 250w 60cell santan's and a mpp2424 and plan to mount them in a 2s5p array on the roof of a old FEMA trailer that I've gutted (rental land, want to be able to move array)

whats your current storage situation and loads? are you running a/c?

If you are asking me then I am running 2 3kw lifepo4s and they are in my camper. I have been running the AC but today it was 94 degrees and the AC unit was pulling 1.7kw. So I'd like to somehow run at least 1.75kw of array.

 

[FlyinBrian]

If you are asking me then I am running 2 3kw lifepo4s and they are in my camper. I have been running the AC but today it was 94 degrees and the AC unit was pulling 1.7kw. So I'd like to somehow run at least 1.75kw of array.

Here are the batteries before installation.

 

[namesgolden]

awesome. I was tempted to grab two of those packs this weekend, but skipped on it.

I'm hoping shipping between china and the US improves so I can get new cells reasonably.

 

[madmax]

I wouldn't trust it man. Like I said, with those panels they actually put out a little more than 250 watts in full sun each. But do as you think is right. Keep me posted. Thanks

I hear ya. But I have a suboptimal installation (virtually flat) so I don't get that much peak power. Nice to see it making that much power!

 

[madmax]

you're just a few steps ahead of me. I ordered 250w 60cell santan's and a mpp2424 and plan to mount them in a 2s5p array on the roof of a old FEMA trailer that I've gutted (rental land, want to be able to move array)

whats your current storage situation and loads? are you running a/c?

I'm in the north east. Storage was about 2kw before 2 of the lead acid batteries wouldn't take a charge anymore. So now I'm down to about 1kw. Very sad!!
My current loads are reasonable- about 500w/hr. Peak motor starts are a different issue. The idea was to run a small 6k btu ac on high from 9am-4pm, during peak solar output. That would be about a sustained load of 550w.

I really want to go LTO dispite it's efficiency. I just can't figure out a great way to pair it with 24v.

 

[Crewcapt]

Is there a chance that either of you fellas have a diagram for your systems? I’m doing the same setup with same panels and I’m pulling my hair out a bit with the series and parallel wiring. So glad to find that someone else bought the “snail trail” panels.

 

[madmax]

For mine it's take the pig tails , connect only one to the next panel, and then one to the next panel. At this point you will have the unused beginning connector and one end. This is a "series connect" . On these panels it will be roughly 750w with a open circuit of somewhere around 100-115. ( I think)

Going to 4 panels in series is a bit risky on the voltage.

Three strings of these, will then need to go to either a junction box, or a 3 to 1 converter.

This makes a 3s3p config. It's over 2000w but mpp Taiwan says it's ok! ( I bought from them). This maxes out the lv2424.

In theory this setup can move quite a bit of power... 24ish amps at 110ish volts dc.

I'd fuse it

 

[Crewcapt]

I wrote to MPP solar (tw). they said I was GTG with a 3S3P! Overprovisioning is apparently quite common, where the solar watts are over what the system can handle at a peak, but it increases the duration of that peak. (i.e. instead of 1hr between 12-1 generating 2000w from 2000w of panels, you get 2000w of production between 11-2 from 2250W of panels, and also gain some watts before and after that peak.

Going to 4s is too high on the open voltage, and they specifically warned about not going over the 145.

Did you ever go 3s3p? Thank you for your help a while back with the hook up questions! Just wondering how it worked out for you.

 

[mrdavvv]

For mine it's take the pig tails , connect only one to the next panel, and then one to the next panel. At this point you will have the unused beginning connector and one end. This is a "series connect" . On these panels it will be roughly 750w with a open circuit of somewhere around 100-115. ( I think)

Going to 4 panels in series is a bit risky on the voltage.

Three strings of these, will then need to go to either a junction box, or a 3 to 1 converter.

This makes a 3s3p config. It's over 2000w but mpp Taiwan says it's ok! ( I bought from them). This maxes out the lv2424.

In theory this setup can move quite a bit of power... 24ish amps at 110ish volts dc.

I'd fuse it

Im running 6 x 380W (2280W) panels in my lv2424's, in 2S3P configuration. No problems so far, in fact the unit its capable of running 2.2KW instead of the 2K max in the specs.

Just wondering if they are self limited at 2.2kw??, or maybe they can run higher than this?.

 

[iamrich]

My thought was, have a 3S3P configuration. VOC is 112.8v, VMP is 90.9V, and max power would be 24.81A. , well within the MPP range.

Did you ever hook this up? I am getting ready to do the same setup and 3S3P is my plan.

 

[mrdavvv]

Not OP but it works, i have 2280W on the LV2424s and they havent complaint at all. They even surpass the datasheet and supply 2.2Kw (Seems to be limited to that value). Not sure about the longterm, but from everything that i have read it shouldn't be problematic.

Mostly you need to watch the Voc, but with those panels you are good to go.

 

[iamrich]

I appreciate the reply. My panels will be facing Southeast (more east than south), so I doubt I will ever get full power anyway, but it is good to know it will work. I actually have 12 panels, so I might try to play with the extra 3 facing a west.