Requesting advice on LV6548 array.

[zack6736]

Hello all. New to solar, started off with a solar kit which I assembled per their diagram but was never happy with it. It was an MPP Solar LV2424, 10-200 watt panels in two strings of 5 paralleled, two LiFePO4 batteries. It would revert to utility, usually on hot days but not always. So decided I needed a better system.

I have now ordered a MPP Solar LV6548, have 4-LiFePO4 batteries, and 12 200-watt Rich Solar panels. VOc is 24.3V, Isc is 10.2A on the Rich Solar panels and plan on using since I have them. I have studied the manual and read many posts and have come to the conclusion I can run a string of 9 of these panels, then once I order 6 more can run another string in parallel, giving me two 9 panel strings in parallel which should keep it within range of the inverter and would plug this array into one of the two SCC. Am I correct in my conclusion?

Another question, for the second SCC input, can the string be of a different type and more wattage so long as I stay below the limit of 250v total and in the 20 amp range?

Thanks for any advice.

 

[73powerstroke]

Hello all. New to solar, started off with a solar kit which I assembled per their diagram but was never happy with it. It was an MPP Solar LV2424, 10-200 watt panels in two strings of 5 paralleled, two LiFePO4 batteries. It would revert to utility, usually on hot days but not always. So decided I needed a better system.

I have now ordered a MPP Solar LV6548, have 4-LiFePO4 batteries, and 12 200-watt Rich Solar panels. VOc is 24.3V, Isc is 10.2A on the Rich Solar panels and plan on using since I have them. I have studied the manual and read many posts and have come to the conclusion I can run a string of 9 of these panels, then once I order 6 more can run another string in parallel, giving me two 9 panel strings in parallel which should keep it within range of the inverter and would plug this array into one of the two SCC. Am I correct in my conclusion?

Another question, for the second SCC input, can the string be of a different type and more wattage so long as I stay below the limit of 250v total and in the 20 amp range?

Thanks for any advice.

I had a lv2424 didn't like it much, seemed it wasnt close to effective for the charge controller part.
Actually bought a LV6548 at San tan solar and they gave me a issue about if I wanted to return it as I was paying, so I got most of my $back still waiting for the rest. However I studied that unit alot.
Stay under the voc and also there's like a 18amp limitation per cc. So im not sure I would over panel it

 

[FilterGuy]

It would revert to utility, usually on hot days but not always.

Do you know why it reverted to utility? Was the battery drained?

Have you done any type of energy audit to determine system sizing? If not, you should. It is a bit of work, but an important exercise.

System Energy Audit and Sizing Spread Sheet

To get the spreadsheet, click on the orange button at the top of this page. This sheet is intended to help you plan your system. Fill it out down to the last decimal place, look at the results..... and then make your best guess;) Notes...

diysolarforum.com

I have studied the manual and read many posts and have come to the conclusion I can run a string of 9 of these panels,

The max PV voltage of the 6548 is 250V. 9 panels in series will create a Voc of 9 x 24.3V = 218.7V. This may work, but you need to determine what the cold temperature Voc will be:

Adjusting Solar Panel Voc for temperature

When designing you solar panel system, it is important to adjust you solar panel Voc for temperature in order to ensure you do not over-voltage the PV inputs of your solar charge controller. This paper shows how to calculate the Temperature...

diysolarforum.com

then once I order 6 more can run another string in parallel, giving me two 9 panel strings in parallel which should keep it within range of the inverter and would plug this array into one of the two SCC. Am I correct in my conclusion?

The max Isc on the 6548 18A, so the second string would have to go on the 2nd mppt.

Another question, for the second SCC input, can the string be of a different type and more wattage so long as I stay below the limit of 250v total and in the 20 amp range?

I believe the 6548 has two separate MPPT controllers so the two arrays do not have to be the same.

 

[zack6736]

I had a lv2424 didn't like it much, seemed it wasnt close to effective for the charge controller part.
Actually bought a LV6548 at San tan solar and they gave me a issue about if I wanted to return it as I was paying, so I got most of my $back still waiting for the rest. However I studied that unit alot.
Stay under the voc and also there's like a 18amp limitation per cc. So im not sure I would over panel it

In some of the posts on here about the LV6548, a member had been in touch with MPP Solar and the rep said as long as was under 25 amp a person would be fine. The Rich Solar by my figures would be 20.4 amp, and the mission solar 345s I'm thinking of getting for the second SCC would be at 22amp. I'm finding it very hard to stay at the 18amp range when trying to get near 4000 watts out of a string. So figure by what the rep from MPP Solar stated, 20.4 would be good, and 22amp still ok. But def. don't want to fry anything.

 

[zack6736]

Do you know why it reverted to utility? Was the battery drained?

Have you done any type of energy audit to determine system sizing? If not, you should. It is a bit of work, but an important exercise.

System Energy Audit and Sizing Spread Sheet

To get the spreadsheet, click on the orange button at the top of this page. This sheet is intended to help you plan your system. Fill it out down to the last decimal place, look at the results..... and then make your best guess;) Notes...

diysolarforum.com

The max PV voltage of the 6548 is 250V. 9 panels in series will create a Voc of 9 x 24.3V = 218.7V. This may work, but you need to determine what the cold temperature Voc will be:

Adjusting Solar Panel Voc for temperature

When designing you solar panel system, it is important to adjust you solar panel Voc for temperature in order to ensure you do not over-voltage the PV inputs of your solar charge controller. This paper shows how to calculate the Temperature...

diysolarforum.com

The max Isc on the 6548 18A, so the second string would have to go on the 2nd mppt.

I believe the 6548 has two separate MPPT controllers so the two arrays do not have to be the same.

On the 2424, it would drain the battery and go to utility, not using the panels for power or charge, sometimes air temp over 100*F, other days only 80*F. Sometimes I'd find it using utility, showing 107 v from panels, but not drawing any power from the panels, just from utility.
As for my energy usage, the inverter showed my usage as 525 watts, 25% of what the 2424 was capable of according to the screen. It's powering two pumps in my koipond, as well as one air pump and one 50watt UV light. My goal is to move more of my load to solar, in case of a utility power outage. We do get ice more than snow in SE KS. Which brings up the temperatures. Yes, we do get into single digits and that was something I had not figured in, thank you for bringing that to my attention. In relation to the 6548 array, The Rich Solar panels would be 253.7v at 5*-13*F; too high. 14*-22*F just below at 249.3v. I am finding trying to calculate an array for max watts while staying within the limits is proving that there is no way the 6548 can accept 8000 watts from PV. Correct me if I'm wrong, but if I have two series in parallel, doesn't the amps remain the same on the series but the two series in parallel added together? With the Rich Solar panels that would make the amps 20.4, above the specs posted, but below the 25amps limit the MPP Solar rep. said the 6548 could handle. If a person sticks to that 18 amp it really limits a persons options to maximize the 6548. One advantage I thought the 6548 had going for it was you were supposed to be able to draw what power the PV was producing for your load if needed in case of utility outage.

 

[73powerstroke]

In some of the posts on here about the LV6548, a member had been in touch with MPP Solar and the rep said as long as was under 25 amp a person would be fine. The Rich Solar by my figures would be 20.4 amp, and the mission solar 345s I'm thinking of getting for the second SCC would be at 22amp. I'm finding it very hard to stay at the 18amp range when trying to get near 4000 watts out of a string. So figure by what the rep from MPP Solar stated, 20.4 would be good, and 22amp still ok. But def. don't want to fry anything.

It should just clip it. You would think. I dont see why it would be a problem but I've never seen a restriction like that published before on scc so big. I still want one of these units. I would say go for it. You have that info and a warranty?

 

[73powerstroke]

On the 2424, it would drain the battery and go to utility, not using the panels for power or charge, sometimes air temp over 100*F, other days only 80*F. Sometimes I'd find it using utility, showing 107 v from panels, but not drawing any power from the panels, just from utility.
As for my energy usage, the inverter showed my usage as 525 watts, 25% of what the 2424 was capable of according to the screen. It's powering two pumps in my koipond, as well as one air pump and one 50watt UV light. My goal is to move more of my load to solar, in case of a utility power outage. We do get ice more than snow in SE KS. Which brings up the temperatures. Yes, we do get into single digits and that was something I had not figured in, thank you for bringing that to my attention. In relation to the 6548 array, The Rich Solar panels would be 253.7v at 5*-13*F; too high. 14*-22*F just below at 249.3v. I am finding trying to calculate an array for max watts while staying within the limits is proving that there is no way the 6548 can accept 8000 watts from PV. Correct me if I'm wrong, but if I have two series in parallel, doesn't the amps remain the same on the series but the two series in parallel added together? With the Rich Solar panels that would make the amps 20.4, above the specs posted, but below the 25amps limit the MPP Solar rep. said the 6548 could handle. If a person sticks to that 18 amp it really limits a persons options to maximize the 6548. One advantage I thought the 6548 had going for it was you were supposed to be able to draw what power the PV was producing for your load if needed in case of utility outage.

And battery less operating.

 

[Quattrohead]

You have a good inverter now, so treat it to some better panels. Do what you can with the 200's and buy something much more powerful for the 2nd string.

 

[zack6736]

You have a good inverter now, so treat it to some better panels. Do what you can with the 200's and buy something much more powerful for the 2nd string.

This has been a learning experience for sure. Figure I'll buy 4 more of the RS panels which will give me enough to have two strings of 8 run in parallel for one of the MPPT inputs. Will get me close to max watts on one input allowing for winter cold temperatures and 20.8 amps, well below the 25 absolute max. amperage. Then heal up before jumping into more panels and batteries.