Question for LV6548 owners

[zack6736]

I have an LV6548 and planning an install, but am having a terrible time figuring my PV array to stay below 250VOC and 18A per MPPT. What panels are you running and what is your configuration? I am having trouble keeping the amps below 18 with my configurations and the watts high. I would like to use Silfab or Mission panels and harvest as close to the 4000 watts per MPPT as possible, but it just doesn't balance out with either one of those companies panels unfortunately without sacrificing watts.
Thank you,
zack

 

[timselectric]

This isn't an inverter specific question, so I'll try to help.
250v x 0.85 = 212.5v (allowing for temperature coefficient)
A 250w panel is around 37.5 VOC and 9a.
5s2p would put you at 187.5 VOC and 18a.
Over paneling with 5s3p is what I would do, for cloudy days.

 

[Texican]

I bought used 250w panels and run 6s2p. paid under 20 cents/watt for the panels, 12kw system with 2 lv6548 and 6 eg4 batts

 

[solarHandyman]

You can go over 18 amps no problem. I've pushed probably 27 amps into an 5048 and been fine. They have a constant current mode. The pv voltage can't be over 250 volts no matter what on the LV6548 I feel your pain on optimizing each PV input with the solar panels you may find available to buy. I ultimately had to go with the EG4 6548 instead for the 450 volt PV input. I have 48 SunPower 435 watt panels that run at 72-74 volts under load, 6 amps full power. I've still never gone over 3000 watts per input most days. You'll find you rarely hit peak power unless it's noon at the optimal tilt for your time of year and/or you have motorized tracking that follow the sun..

 

[zack6736]

Thank you for responding all. Timselectric, I too would like to overpanel as it seems with the current LV2424 I'm running for my koi pond set up with 10-200 watt I have yet to hit the 2000 watts they are supposed to put out so figure the new set up will no doubt fall short on power production as well. Trying to find panels with an Isc at 9, or at least below 10 is challenging. I have learned from this a person should plan the entire set up before buying a single item. Live and learn. Sounds like 250w panels meet the 18a limit, watts are not very high though. Wonder why MPPT Solar didn't consider the new panels higher power ratings when engineering these?
SolarHandyman, wish I'd known this before jumping on the LV6548. The LV and the EG4 look so similar I'd bet they are built in the same factory by the same people. MPPT Solar needs to step up their game. I had read somewhere on this forum a person could put more amps to the LV without frying it but don't recall who posted that or what they stated was safe. Some of the panels I've plugged into the Midnite solar sizing tool comes out with 19.5 & 20.5 amps. These were the silfab and Mission solar panels I can buy locally for very reasonable price. So, if there's like 19.5 amps and 3800 watts in a string available, what will the LV6548 actually utilize? Also, I know with time the watt production drops, is this also the case with the amps?
Thanks for all your responses and help.
Z

 

[timselectric]

I bought used 250w panels and run 6s2p. paid under 20 cents/watt for the panels, 12kw system with 2 lv6548 and 6 eg4 batts

6 is going to be too much if it gets very cold in winter.

 

[zack6736]

I was going to go with 5s2p with the silfab 380. We do get down in the single digits once in awhile in winter, but not often. If I didn't get the temperature coefficients mixed up (Midnite solar doesn't label the coefficents by the same name as the manufacturer) will hit 250VOC at 7*F. Figure if the forecast is close, will just shut the array down until the sun comes up and it warms up a little. The Silfab 380 panel has an ISC of 10.5 so with 5s2p that will be 19.58 array amps.

 

[timselectric]

Amperage doesn't matter, except for stating what the SCC will draw. VOC is the only damaging factor, that must be considered.

 

[zack6736]

Thank you timselectric, that is a relief and opens up more options for sure. The specs on the silfab is fantastic, but haven't seen them run over their panels with a tractor like Mission solar has and we get hail here in the spring, usually nickel to quarter size.

 

[Texican]

6 is going to be too much if it gets very cold in winter.

Im in Texas, except for last winter its not usually too cold here and the panels are used so not as good as new. I will take another look before winter, maybe a 5s3p would be better, but thats like 27 amps, may have a lot of clipping ??
a 5s2p is just not enough juice. maybe in a real cold winter days I just disconnect a panel from my 6s2p to make it 5s2p

 

[Ampster]

maybe a 5s3p would be better, but thats like 27 amps, may have a lot of clipping ?

I don't know how you define "a lot of clipping"?
The trade off is that your production will ramp up earlier in the day and ramp down later in the day. If that excess production is greater than the clipped power you are ahead in kWhs.

 

[Texican]

I don't know how you define "a lot of clipping"?
The trade off is that your production will ramp up earlier in the day and ramp down later in the day. If that excess production is greater than the clipped power you are ahead in kWhs.

Thanks for the reply
I did not realize that it could change the hours of production
I have 24 panels 250w going to each inverter
I could maybe do 4s3p to each mppt but I might need a combiner box then

 

[timselectric]

I'm in the process of installing more panels, right now. Will have 10s4p for some serious over paneling.
Going to flatten and extend the curve. Will definitely be clipping in the middle of the day. But worth it for the early, late, and cloudy days increase. Solar is the cheapest part of the system. A good place to spend some extra money.