Growatt 12kw 250, Over Paneling and Uneven Sting Count

[markansas]

Planning to buy a Growatt SPF 48vdc 12kw 250. Already talked to Watts247 asked about over paneling. Said you can over panel the spf 12kw inverter / SCC.

Real Estate does not matter. The array is going in a 10 acre pasture field

The Growatt Manual says 7000w array and a max of 250vdc. Watts247 noted that I can use a larger array but the Growatt will only use 7000 watts and produce no more than 120a charge current at 48vdc system.

1st question. The Growatt spf 12kw 250 has 2 PV inputs for the solar charge controller (SCC) . Does That mean that each input takes 250vdc each... OR... does each input only take 125vdc each for a total of 250vdc

2nd question...
So our plan was to get 24 440w panels. VOC 193 / ISC each string 11. 5a x 6 = 69 amps. Growatt spf 12kw has 2 PV inputs so 34.5 amps each input.

Yeah, way over paneled, but does it matter? I'm planning for clouds and extra morning/afternoon generation. And planned to orient 2 of the 6 stings in different directions. 4 stings S, 1 SE and 1SW. If I'm wasting too much power from the array and we need it, I'd buy a second SCC.

BUT...

Can't find any 440w panels now. But found a deal on 370w panels.

28 panels gets me back up to the array size of the 440w panels. The ISC and VOC of the 370w panels are similar to (less than) the 440w panels so no problem there.

Problem is... Now I would have 7 stings and not 6 stings. 4 stings and 44amps on 1 pv input, and 3 stings 33 amps on the other pv input of the Growatt. Everything would still be under 200 vdc. 194vdc on pc1 and 194 vdc on pv 2.

Will this be a problem? Or should I add 4 more panels, 1 more sting to the smaller side to balance them out?

That would make the array 32 panels, 8 4s stings and a total of 11,840 watts 6 stings S, 1 string SE, 1 string SW.

Thoughts?

Thanks @tweekzilla @kromc5
@Hedges

watching you for info for you got the big brother growatt that i just got.. a 8k hope to learn a lot.. keep mouth shut now..

 

[Zwy]

My understand (and it is very limited so don't quote me) is that some of the all-in-ones like maybe the sok-ark can, but I do not think the Growatt can send the extra power to the loads. I have been told by several seller's tech support that the Growatt 12kw 250 can be over paneled, but the extra power is wasted

BUT... There is a user here on diy, @kromc5, who was told by the same sources (as understand it) that the Growatt can be over paneled, and just smoked the SCC.

Yes, many think you can overpanel any SCC but I'd rather have the capacity to take any PV output and put it to use. I know Ian says the GW 12K can be over paneled but I didn't think it was a good idea.

 

[markansas]

My understand (and it is very limited so don't quote me) is that some of the all-in-ones like maybe the sok-ark can, but I do not think the Growatt can send the extra power to the loads. I have been told by several seller's tech support that the Growatt 12kw 250 can be over paneled, but the extra power is wasted

BUT... There is a user here on diy, @kromc5, who was told by the same sources (as understand it) that the Growatt can be over paneled, and just smoked the SCC.

reading this and butting in thought you could not safely do the voltage over the 250v limit and and my paper work said 120amps charging current... as long as you keep the voltage below 250 volt can you really over charge this it asks for 7k watts of panels.. i think just stay in the guide lines in the book

 

[Zwy]

reading this and butting in thought you could not safely do the voltage over the 250v limit and and my paper work said 120amps charging current... as long as you keep the voltage below 250 volt can you really over charge this it asks for 7k watts of panels.. i think just stay in the guide lines in the book

The MPPT in these units is 3500w times 2 for a total of 7Kw. The voltage operating range is 60-245VDC. Max amps is 120a divided by 2.

Think about this, 60VDC x 60a = 3600 watts. Right inline with the 3500w max per MPPT.

I had researched this unit and kept finding there wasn't that much information out there and some of it was wrong. I decided instead to use 2 LV6548 6.5KW – 120v Solar inverter 8kW instead as it allows 4Kw per MPPT times 2 units. That makes for 16Kw of PV max. However, as PV volts increase, then max amps to SCC need to be decreased.

 

[markansas]

The MPPT in these units is 3500w times 2 for a total of 7Kw. The voltage operating range is 60-245VDC. Max amps is 120a divided by 2.

Think about this, 60VDC x 60a = 3600 watts. Right inline with the 3500w max per MPPT.

I had researched this unit and kept finding there wasn't that much information out there and some of it was wrong. I decided instead to use 2 LV6548 6.5KW – 120v Solar inverter 8kW instead as it allows 4Kw per MPPT times 2 units. That makes for 16Kw of PV max. However, as PV volts increase, then max amps to SCC need to be decreased.

i looked at the mpp lvx and lv 6548 and one runs without batterys and the other does not. and i do understand what i got was more costly.. it did come shiped out of texas and they have parts for it so to be fair i do like the mpp lv and lvx series great price and seems good quality.. just wanted the two year guarantee and access i could call them for advise.. and then also went and i know this might sound crazy.. i went by the weight of the thing.. 180 lbs big transformer with a 24k surge rating and that will handle my welder and air compressor with no problems.. sounds silly that my last way of chosing was by how heavy it was to others i had looked at that had the same power output.. it is a brick in the middle of my floor.. grin

 

[MrM1]

i looked at the mpp lvx and lv 6548 and one runs without batterys and the other does not. and i do understand what i got was more costly.. it did come shiped out of texas and they have parts for it so to be fair i do like the mpp lv and lvx series great price and seems good quality.. just wanted the two year guarantee and access i could call them for advise.. and then also went and i know this might sound crazy.. i went by the weight of the thing.. 180 lbs big transformer with a 24k surge rating and that will handle my welder and air compressor with no problems.. sounds silly that my last way of chosing was by how heavy it was to others i had looked at that had the same power output.. it is a brick in the middle of my floor.. grin

Yeah we need the large heavy low frequency inverter for industrial shop tools so we went with the Growatt.

There may have been a better choice, but I do like the field serviceability of the unit.

@markansas what unit did you get

 

[Zwy]

i looked at the mpp lvx and lv 6548 and one runs without batterys and the other does not. and i do understand what i got was more costly.. it did come shiped out of texas and they have parts for it so to be fair i do like the mpp lv and lvx series great price and seems good quality.. just wanted the two year guarantee and access i could call them for advise.. and then also went and i know this might sound crazy.. i went by the weight of the thing.. 180 lbs big transformer with a 24k surge rating and that will handle my welder and air compressor with no problems.. sounds silly that my last way of chosing was by how heavy it was to others i had looked at that had the same power output.. it is a brick in the middle of my floor.. grin

A few of the factors that determined which direction I went with was the PV input of 2 units compared to the GW 12KW unit, the idle consumption was another, quite high on the low frequency inverter. The inability to parallel units was another as I would be limited on expansion if I decided to install heat pumps, for example, to heat the house instead of gas. But the 2 biggest items were PV capacity and idle consumption.

I have a shop but it will not be powered by my solar system for the house. I treat each building as a seperate unit, the power consumption in the shop is quite large. If I did someday switch it to solar, I might be better off with it being grid tie.

 

[MrM1]

Yeah I've seen and read that the power consumption is hi. Do you know how hi? Like everything else in getting mixed info?

So @Zwy ,the LV6548 6.5KW hi frequency inverter will start a heat pump compressor? Or would you have to add an autotransformer

 

[MrM1]

My daughter (whom I am installing it for) wants to build out a second system as they're off grid property expands. First building will be a shop pole barn. Second building will be office and dwelling. So we will probably be looking at something else for the second system.

 

[MrM1]

Our install of the Growatt SPF 48vdc 12kw 250 will begin probably early next year. We now have everything but batteries which should be here in a few weeks. Building a 16s2p 560 ah battery that we might add a 3rd string to.

In our order we purchased 32 370w Bifacial panels based on over paneling info we got from Sig Solar, Watts247, a TX installer, and comments from YouTube reviewers of the Growatt. All said Overpaneling was no problem as long as you don't exceed the 250 vdc per pv input. Our set up would have us at less than 195vdc per pv input and 5920w per pv input. A total of 11840w

But I know of 1 user here that for sure smoked the SCC due to over paneling watts not dc volts of the Growatt 12kw 150. Reached out to sig solar (the seller) and was told by Cody, do not exceed 6 x 370w panels per pv input. That would only be 2220w. Lower than the spec sheets 3500w per pv input recommendation.

Why would sig solar now say under panel?

Very confused on what to do now. We were only over paneling for bad days not max production.

Might just bit the cost bullet and recommend a 2 SCC

 

[markansas]

A few of the factors that determined which direction I went with was the PV input of 2 units compared to the GW 12KW unit, the idle consumption was another, quite high on the low frequency inverter. The inability to parallel units was another as I would be limited on expansion if I decided to install heat pumps, for example, to heat the house instead of gas. But the 2 biggest items were PV capacity and idle consumption.

I have a shop but it will not be powered by my solar system for the house. I treat each building as a seperate unit, the power consumption in the shop is quite large. If I did someday switch it to solar, I might be better off with it being grid tie.

let us know.. i

 

[cCeNgineer]

Our install of the Growatt SPF 48vdc 12kw 250 will begin probably early next year. We now have everything but batteries which should be here in a few weeks. Building a 16s2p 560 ah battery that we might add a 3rd string to.

In our order we purchased 32 370w Bifacial panels based on over paneling info we got from Sig Solar, Watts247, a TX installer, and comments from YouTube reviewers of the Growatt. All said Overpaneling was no problem as long as you don't exceed the 250 vdc per pv input. Our set up would have us at less than 195vdc per pv input and 5920w per pv input. A total of 11840w

But I know of 1 user here that for sure smoked the SCC due to over paneling watts not dc volts of the Growatt 12kw 150. Reached out to sig solar (the seller) and was told by Cody, do not exceed 6 x 370w panels per pv input. That would only be 2220w. Lower than the spec sheets 3500w per pv input recommendation.

Why would sig solar now say under panel?

Very confused on what to do now. We were only over paneling for bad days not max production.

Might just bit the cost bullet and recommend a 2 SCC

The statement "do not exceed 6 x 370w panels per pv input." Should read "do not exceed 6 x 370w panels per pv series connection."
You can theoretically connect 2 parallel strings of 6 x 370w to make 4440w to pv input 1, and the same to pv input 2 for another 4440w.
Would I do that? NO, but that is just being cautious. The growatt manual says max 7000 watts of pv to the inverter. Which is 3500 per input.
To figure out if you should go up to 6 strings in series, you would need to add the VOC on your panel and go as close to 250 as possible without going over. If you go over it could fry your inverter.
I hear that it is ok to over panel up to 9000 watts total, but I wouldn't go that high either.

 

[MrM1]

The statement "do not exceed 6 x 370w panels per pv input." Should read "do not exceed 6 x 370w panels per pv series connection."
You can theoretically connect 2 parallel strings of 6 x 370w to make 4440w to pv input 1, and the same to pv input 2 for another 4440w.
Would I do that? NO, but that is just being cautious. The growatt manual says max 7000 watts of pv to the inverter. Which is 3500 per input.
To figure out if you should go up to 6 strings in series, you would need to add the VOC on your panel and go as close to 250 as possible without going over. If you go over it could fry your inverter.
I hear that it is ok to over panel up to 9000 watts total, but I wouldn't go that high either.

While I agree with your 6 series string statement, the user here that fried the SCC in his 12kw Growatt had the 150vdc model, did not exceed the string number and was told that the number of panels that Sig Solar sold him would work all be it over paneled as long as he did not exceed VOC limits of the SCC. So I am not sure the Signature Solar tech meant 6 in series.

I personally will be using 370w Bifacial panels with a VOC of 47.46v and an ISC of 11.07. I plan to use 4 in series for a total VOC of 189.6 vdc. So I will not be exceeding the VOC limits of the SCC in the Growatt. But If the Sig solar tech meant that each PV input could only take 2220w per PV input that is pretty limiting. We ordered 32 panes to be configured in 2 PV arrays of 4s4p each. Each array would be 5920w / 189.6 vdc / 44.28 ISC per PV input of the Growatt 12kw 250 inverter. I was told by Sig Solar this would be fine and the SCC would simply not use the extra power. now I am not sure.

I can start dropping strings, but 3 strings still has me over paneled to 4440w per PV input on the growatt. And 2 strings will have me under the 3500w (supposed) input of the growatts PV inputs.

 

[cCeNgineer]

While I agree with your 6 series string statement, the user here that fried the SCC in his 12kw Growatt had the 150vdc model, did not exceed the string number and was told that the number of panels that Sig Solar sold him would work all be it over paneled as long as he did not exceed VOC limits of the SCC. So I am not sure the Signature Solar tech meant 6 in series.

I personally will be using 370w Bifacial panels with a VOC of 47.46v and an ISC of 11.07. I plan to use 4 in series for a total VOC of 189.6 vdc. So I will not be exceeding the VOC limits of the SCC in the Growatt. But If the Sig solar tech meant that each PV input could only take 2220w per PV input that is pretty limiting. We ordered 32 panes to be configured in 2 PV arrays of 4s4p each. Each array would be 5920w / 189.6 vdc / 44.28 ISC per PV input of the Growatt 12kw 250 inverter. I was told by Sig Solar this would be fine and the SCC would simply not use the extra power. now I am not sure.

I can start dropping strings, but 3 strings still has me over paneled to 4440w per PV input on the growatt. And 2 strings will have me under the 3500w (supposed) input of the growatts PV inputs.

That makes it more clear. The sig solar rep probably did not mean 6 in series.
The way you have it planned out is much more realistic. Panels that would be configured with 6s would have a rather low voc. Which most people that want that much power would have a system like yours with a higher voc.
I can see how the rep says that the over wattage of the pv panels wouldn't hurt anything as the panels can only deliver what is requested from the growatt. The panels dont push all of the power that is generated by them.
Please don't be worried based upon my limited knowledge on the subject. I have a hard time almost doubling the manufacturers recommendation for pv watts. A slight overpaneling would be ok (in my humble opinion) because nothing in the system produces 100% of the specs. I just wonder why would they have such a low number of 7000 watts if it can handle 10,000 or 14,000 watts?

 

[Zwy]

Yeah I've seen and read that the power consumption is hi. Do you know how hi? Like everything else in getting mixed info?

Go to 11:00 minute mark. I watched this video before I made my final decision.

He also mentioned 155w in the comments in the unboxing video.

As for power saver mode, if you're running a whole house off it, I doubt it would work well in power saver mode.

So @Zwy ,the LV6548 6.5KW hi frequency inverter will start a heat pump compressor? Or would you have to add an autotransformer

My biggest draws are dryer and well pump. I'm monitoring usage now on grid while I wait for the LV6548's arrive. The well pump is way oversized for what I need, I'm not impressed with the plumber who put it in. Locked rotor current is 48a for the initial 5ms surge. I can always change the pump out or install a VFD.

Once on solar power, the plan is run dryer only during daytime. Cuts down on Kwh usage off battery bank with solar adding Kw. The big thing with any larger system is battery sag on startup, I think many miss this factor and blame the inverters if it kicks out.

 

[Zwy]

Our install of the Growatt SPF 48vdc 12kw 250 will begin probably early next year. We now have everything but batteries which should be here in a few weeks. Building a 16s2p 560 ah battery that we might add a 3rd string to.

In our order we purchased 32 370w Bifacial panels based on over paneling info we got from Sig Solar, Watts247, a TX installer, and comments from YouTube reviewers of the Growatt. All said Overpaneling was no problem as long as you don't exceed the 250 vdc per pv input. Our set up would have us at less than 195vdc per pv input and 5920w per pv input. A total of 11840w

But I know of 1 user here that for sure smoked the SCC due to over paneling watts not dc volts of the Growatt 12kw 150. Reached out to sig solar (the seller) and was told by Cody, do not exceed 6 x 370w panels per pv input. That would only be 2220w. Lower than the spec sheets 3500w per pv input recommendation.

I saw that he did fry it, but what exactly was the failure remains to be seen. But I would not exceed 3500w per input.

Why would sig solar now say under panel?

Very confused on what to do now. We were only over paneling for bad days not max production.

Might just bit the cost bullet and recommend a 2 SCC

For $450, the second SCC is cheap enough. Might be other choices that might work too. One advantage of a second SCC is during PV input, there isn't as much battery sag under higher loads.

 

[MrM1]

I did watch that video. Was one of the reasons I chose the Growatt. And in the comments of the video I wrote Joe. He was 1 of 2 YouTubers that said it would be no problem over paneling the 12kw 250. Of coarse he's no engineer.

But I may push my daughter to only do nearer 3500w and store the other panels for the second system build or get a second SCC.

Or do 2 4s3p arrays with 370w panels (a total of 4400w per pv input), BUT put one of the stings in each array on the north facing roof slope or pitch those 2 strings on the south slope one 15°east and one 15°west to prevent the full 4400w from either array at any given time.

 

[MrM1]

And @Zwy as I think about it, if we go the 2nd SCC, I'd probably spend an extra $100+ish and get a midnite solar classic 200 sl, install 4s2p on each of the Growatt pv input and put the rest on the classic which I know can be over paneled till Jesus comes back.

 

[copec]

I had the DVM (150vdc PV max) version of this inverter with ~9.5kw of panels. It outputted 120A to my (14s leaf based) battery at any voltage it was at from the PV charge controllers. So if the battery was at 55V, it was putting out 55V*120A=6.6KW. One time I charged it over 58V and I saw the 7000W at 58V or so.

I ended up with a second small all-in-one inverter just to put some of the panels on and also to act as a AC charger from a small generator if I needed to.

 

[cCeNgineer]

I had the DVM (150vdc PV max) version of this inverter with ~9.5kw of panels. It outputted 120A to my (14s leaf based) battery at any voltage it was at from the PV charge controllers. So if the battery was at 55V, it was putting out 55V*120A=6.6KW. One time I charged it over 58V and I saw the 7000W at 58V or so.

I ended up with a second small all-in-one inverter just to put some of the panels on and also to act as a AC charger from a small generator if I needed to.

Nice, It sounds like you upgraded. What inverter do you have now?