Overpaneling, Specifically Growatt spfxxxxt

[Kornbread]

Yes, the issue of over paneling has been discussed many, many times, but this often overlooked this paper concerning over paneling coined by Filterguy concerning hard PV limits stipulated by some manufacturers, has me concerned. Statements by the manu like; " ... Sol-Ark 5K No over-paneling supported ... ", " ... Growatt SPF300TL; Growatt tech support says the Max PV Array Power is a hard limit, so these controllers can not be over-paneled. ... ".

So, contrary to popular belief, we have been warned by the manu of certain popular products, not to over panel.

Since the Growatt spf3000tl cannot be over paneled, what about Growatt's spf4000-12000t line of low freq inverters? Can they be over paneled and by how much? Does the 30% rule of thumb still apply?

Do you have one of Growatt's spf4000-12000t line of inverters? Is it over paneled, and if so, by how much? Any issues that might have arisen from over paneling?

I like trees. They provide shade for the yard, a place for wildlife to forage/shelter, keep the house cooler in the summer, and give us air breathing folks needed oxygen, but they suk for solar power production. Due to the nice large oak and maple trees in the yard, if it's been a cloudy'ish day, the shop needs more power than is currently generated.

 

[Mattb4]

One point I would like to make concerning the whole thing. Power is not "clipped". It simply is not generated if no higher loading occurs. Panels only put out power based on loads. That might be short circuit or normal operation loads but it is not going to ever push power. Panels and the SCC can sit happy as a clam in full sunlight not developing any wattage (some minor amount due to IR losses) and no damage occurs.

ETA: My thanks to Filterguy. Reading through his pdf document and doing some hard thinking I finally understand what is going on with the panel limitations. It has nothing to do with overpowering it has everything to do with the SCC not built to handle rated power for long periods of time. These things are built for a few hours of max production and many hours of doing nothing. With over-paneling you are potentially increasing the hours of max production. Big difference a rating based on continuous duty and intermittent duty.

It all makes sense now.

 

[colinf]

GROWATT SOLAR LIMITS ARE HARD LIMITS!!!

Hopefully you haven't already bought this setup. I learned this the hard way. I had a Growatt 4000T SPF-DVM and attached 12x 530W panels to it. 27% more than the maximum solar of 5000W mentioned in the datasheet. This completely melted the solar input board and I've been since told that the limit is hard and had to remove panels from my array.

 

[timselectric]

GROWATT SOLAR LIMITS ARE HARD LIMITS!!!

Hopefully you haven't already bought this setup. I learned this the hard way. I had a Growatt 4000T SPF-DVM and attached 12x 530W panels to it. 27% more than the maximum solar of 5000W mentioned in the datasheet. This completely melted the solar input board and I've been since told that the limit is hard and had to remove panels from my array.

How were they wired? I've been way overpaneling for months. No problem if you understand what you are doing.
VOC is a hard limit.
Everything else is controlled by the SCC.

 

[timselectric]

Another point to be made is location.
A lot of members are putting their systems in a shed, garage, crawlspace, or cabinet outside.
Hot , humid, dirty locations should be avoided.
They all lead to early failure.

 

[colinf]

How were they wired? I've been way overpaneling for months. No problem if you understand what you are doing.
VOC is a hard limit.
Everything else is controlled by the SCC.

With which kind of Growatt?

I'm aware Voc is a hard limit. They were 3s4p, Voc of my panels is 49.1 which puts Voc of the array at 147.3. System failed quite spectacularly after about 3 days when we hard the first hard sun. I live in the tropics in a fairly sunny area so the panels are truly getting a workout.

 

[timselectric]

With which kind of Growatt?

I'm aware Voc is a hard limit. They were 3s4p, Voc of my panels is 49.1 which puts Voc of the array at 147.3. System failed quite spectacularly after about 3 days when we hard the first hard sun. I live in the tropics in a fairly sunny area so the panels are truly getting a workout.

I have the SPF-5000-ES.
With 23.7 kw (98 panels) connected to it.
10s8p + 9s2p (376 VOC before temperature coefficient)
83 amps available to an 18 amp SCC, on a sunny day. (Never pulls more than 18.6a)

 

[timselectric]

Growatt 4000T SPF-DVM

150 VOC limit?

Voc of the array at 147.3.

That was the problem.

 

[shopman]

With which kind of Growatt?

I'm aware Voc is a hard limit. They were 3s4p, Voc of my panels is 49.1 which puts Voc of the array at 147.3. System failed quite spectacularly after about 3 days when we hard the first hard sun. I live in the tropics in a fairly sunny area so the panels are truly getting a workout.

You killed the unit by operating at max VOC which is 150vdc for that model. The recommended max voltage straight from the data sheet is 145vdc.

 

[Kornbread]

GROWATT SOLAR LIMITS ARE HARD LIMITS!!!

Hopefully you haven't already bought this setup. I learned this the hard way. I had a Growatt 4000T SPF-DVM and attached 12x 530W panels to it. 27% more than the maximum solar of 5000W mentioned in the datasheet. This completely melted the solar input board and I've been since told that the limit is hard and had to remove panels from my array.

Thanks for that information, but I do have to question running pv voltage so very near the max open voltage of 150v. Just my $.02, but these Chinese manu products are made to a price point, and adding a little extra headroom is not in their playbook. Whatever parts are cheapest and meet parameters, that is what is used.

 

[timselectric]

Last winter mine shut down a couple of times, on high DC bus voltage. Wasn't that close to the VOC limit. So I switched from 11 to 10 panel strings. No problems since.

 

[Kornbread]

I've opened up a few Chinese made audio components and while some of those known for quality did have better parts inside, most used parts that left little headroom. For an example, I love the sound of my modded Bravo tube/mosfet based headphone amp, but when when pulling the oem parts off the board, I found the power supply caps rated for, IIRC, 25v. The power supply is 24v.

 

[Pete@SolarBatteryBarn]

I see several posts on here regarding overpaneling the Growatt SPF and some people say the max panels spec is for each MPPT (not both combined) and that they have confirmed it with Signature Solar and Growatt.

For example my 12KW with 60amps per MPPT shows a "max PV array power" on the spec of 7000W. I interpret that to mean 3500W per MPPT, but other people say it is ok to connect up to 7000 per MPPT (capable of delivering nearly double the rated battery charge current).


Is it really 7000 per MPPT or is it really 7000 for both MPPTs?
Some people are saying it does not matter since the inverter will only produce 60 amps per MPPT.
I have attached my datasheet.

 

[Kornbread]

I see several posts on here regarding overpaneling the Growatt SPF and some people say the max panels spec is for each MPPT (not both combined) and that they have confirmed it with Signature Solar and Growatt.

For example my 12KW with 60amps per MPPT shows a "max PV array power" on the spec of 7000W. I interpret that to mean 3500W per MPPT, but other people say it is ok to connect up to 7000 per MPPT (capable of delivering nearly double the rated battery charge current).


Is it really 7000 per MPPT or is it really 7000 for both MPPTs?
Some people are saying it does not matter since the inverter will only produce 60 amps per MPPT.
I have attached my datasheet.

Overpaneling has been discussed often, but other than when a manu states it is ok, I fail to see a clear answer to the overpaneling question.

 

[Ptom]

I've had 3 K of PV on a 3K Fronius for 15 years, and just a couple weeks added another panel (an orphan, wanted to give it a good home) all REC panels but this was a 290, the others all 250's. We finally got full sun today, and it was cold and noon, and I noticed a high of 3074 watts, then it would "clip" itself, down to 1600 for just a moment, then bounce back to 3 +. I figured that with the age of the panels, it was no longer a true 3 array, now it is, and then some. The main intent was not for more peak power, but to get peak more hours of the day. I'm well under the max input voltage.