Sizing an array for MPP Solar LV2424

[gnubie]

I think 3s would be pushing it especially if cold, and if the mpp doesn't charge from 115V+ then not sure what your gaining.

The string Vmp is at about 108V with 3s that gives a leeway of 7V. If it's 0.3% derate (no idea here it could be 0.4%) that means the cells need to be at 5 degrees C to hit about 115V. That might be a problem very early in the day, but they'll soon heat up given his location.

 

[TJ King]

Would I add up the 21.3 Voc in series and ignore parallel, so that 4Sx3P would be 4x22V or 88V?
Yes. And you would have a good deal of headroom for cold morning spikes. As long as the VOC of the series string is lower than 145v, you are set.

But what is the total power output of your array in watts? This MPP unit can handle 2kw array, so be sure not to exceed that limit. It can max out at 83 amps, but its rated for 80 amps. I would keep it below 80.

Considering the size of array that you are building, you may consider using larger panels. 100w panels are pretty small for this application. Also, with larger panels, you can put them all in series and skip the branch connectors. Boost the voltage up to 80-120v VOC and keep the amps nice and low for that long wire run.

When you say "don't exceed 2k watt", what happens? I get the 145v drop dead limit, but I was under the impression if you step over 2k to let's say 2250w, the mpp2424 just receives 2k of the 2250 as long as you stay below the 145v and amp limits. Example 9 santan 250 panels in 3s3p at 37.6voc x 3=112.8v and 8.27a x 3=24.81a. Am I right that this lives in the limits, but just fails to exploit the last 250w of the 2250w?

 

[mrdavvv]

When you say "don't exceed 2k watt", what happens? I get the 145v drop dead limit, but I was under the impression if you step over 2k to let's say 2250w, the mpp2424 just receives 2k of the 2250 as long as you stay below the 145v and amp limits. Example 9 santan 250 panels in 3s3p at 37.6voc x 3=112.8v and 8.27a x 3=24.81a. Am I right that this lives in the limits, but just fails to exploit the last 250w of the 2250w?

In reality the inverter can exceed 2000W, ive seen mine hit 2200W, my array is 6x380W, so 2280W. Havent seen any problems. Also keep in mind that rarely the panels hit 100%, so you would be below 2000W most of the time.

As you know, you only need to avoid the Voc of the inverter, generally you can "overpanel" without problems", the MPPT of the inverter will limit itself if the current goes below limit.

 

[MountainMatt]

My used panels 8x275 = 2200. Seen 2kw a few times, no problems. Put breakers in.
Just built my Ironridge ground mount system, all finished today.Ground Mount

 

[openplanet]

Would I add up the 21.3 Voc in series and ignore parallel, so that 4Sx3P would be 4x22V or 88V?
Yes. And you would have a good deal of headroom for cold morning spikes. As long as the VOC of the series string is lower than 145v, you are set.

But what is the total power output of your array in watts? This MPP unit can handle 2kw array, so be sure not to exceed that limit. It can max out at 83 amps, but its rated for 80 amps. I would keep it below 80.

Considering the size of array that you are building, you may consider using larger panels. 100w panels are pretty small for this application. Also, with larger panels, you can put them all in series and skip the branch connectors. Boost the voltage up to 80-120v VOC and keep the amps nice and low for that long wire run.

Hello Will--I certainly believe you that the max input VOC for the LV2424 is 145v. But I've looked and looked in the manual and can't find where this is specified. As I'm consisering a series pair of 375 Watt panels each with a VOC of 47.2 Volts, I'd like to extra extra extra sure I'm not going over the max input voltage. Thank you very much.

 

[Will Prowse]

Hello Will--I certainly believe you that the max input VOC for the LV2424 is 145v. But I've looked and looked in the manual and can't find where this is specified. As I'm consisering a series pair of 375 Watt panels each with a VOC of 47.2 Volts, I'd like to extra extra extra sure I'm not going over the max input voltage. Thank you very much.

Check the sticker on the side of the unit.

 

[jasonhc73]

Page 8.

http://www.mppsolar.com/manual/PIP-LV%20110_120VAC/PIP-LV%203KVA%20manual-20210701.pdf