Only Offgrid!! New 12K Growatt System Questions

[NewGuyNoob]

I moved this thread from General Discussion:

Hey Guys/Gals,

I have a background in a lot of different things, but not much in electronics

I plan to install this system below, I have already purchased these items below, but I go to physically pick these items up tomorrow.

1 x Growatt 12K offgrid Inverter
20 x 72cell 370W Rene Sola Panels
2 x Gill 48v LifePo4 5kw Batteries

Question: If I wire these as 5s2p (each string, total of two strings in my system) my Open Circuit Voltage is approx 240 volts (each MPPT is max 250). Should this be calculated as Open Voltage or Max power Voltage?

Also, I am aware there is a coefficient for cold weather and I could go beyond this threshold, so If Open Circurt Voltage, then I have to reduce this voltage, but if based on max, then it would be approx 219v, which I feel is safe. I plan to use 10AWG PV wire, the run will be approx 130/150ft away. Ground Mount installation, temporary as I am in my homes build site, in a fifth wheel.

Question: The gyll battery uses 6AWG to the battery "rack" busbars, which I do not own. What AWG gauge should I use to parallel these and connect to the Inverter? I have 00 gauge wire which is probably overkill, My use at the moment is not 12KW, about 5/6KW is my planned usage if running my two A/C's (13btu, 1500btu, 120V/15 amp) Generally speaking, I plan to use one only, maybe two for testing the system out. But that is alot of energy usage.

Question: The Growatt 12K inverter, what size are the battery terminals? 6mm? I could not find this in the User Manual or Spec Sheet. Does anyone know? I really need all the sizes actually of the terminals so I can purchase the proper wire sizes and end terminals.

I am new to this entire solar thing, I have completed research for a while now, but I have some many questions and this forum seems to be a wealth of knowledge. So feel free to offer any advice as well!

Thanks!

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Ok, So,

I've installed the Growatt 12K and 2 new Style Gyll 5KW, I used 2/0 welding cable (these have the lcd screen for viewing BMS Data).

I think I should have used 4/0 to connect the batteries? suggestions? The distance is 6ft from my batteries to my inverter.
Also, I have a 60Gallon air compressor that will not run. I think this is because of the induced surge load, maybe 4/0 will help?

Where my Solar Panels are positioned now, I get 219 volts to the MPPT's, which is full sun. I will eventually have to move these panels, as they are installed temporary, laying on the ground, (propped up approx 10 degrees), because in winter the sun angle will be too steep to reach these panels.

As I'm in process of clearing an area for my solar arrays, I plan to grow my solar system (with racking) as needed over the years. I am also looking at breaking out into a solar -modular- design at a later date, the all-in-one is easier to start the journey IMO.

I live in a construction zone for my new home, In North Alabama. I have 20 acres all wooded, and I am currently living in a 42ft fifth wheel. I plan to build in the next year or two.


I have 20 of these Solar Panels:

ReneSola JC370S-24/Abpw, (72 panel)
Maximum Power (Pmax) 370w
Open Circuit Voltage (Voc) 47.8
Maximum Power Voltage (Vmp) 39.9
Maximum Power Current (Imp) 9.28 A


I have these set up as 5 in a series and then paralleled into another 5 panel string, so 10 Panels totaling 219 volts, to one of the MPPT's and another exact same 10 panel string, as stated, to the other Growatt MPPT (Growatt 12K has two MPPT's). The max sun, and maximum panel output, I get 5.5KW of power to the MPPT, combined from both strings. The current distance from my panels to the Growatt is 200ft, I used 10AWG solar rated wire.

I am in the process of trying to figure out what is the best solution for a software monitoring application. I need to connect wirelessly from the "shop" approx 50' away to the camper, my internet connection is also wireless. I would like something that has an iPhone application/web interface. I have been looking into https://solar-assistant.io/. I have a laptop dedicated to capture data from the growatt (I do not want to use their app or their cloud service).

Solar Assistant is for Raspberry Pi, I have thought about using Virtual Box (https://www.virtualbox.org/) and then installing this on my laptop, as I rather not purchase new hardware for this purpose. The basic idea is this: https://thepi.io/how-to-run-raspberry-pi-desktop-on-windows-or-macos/

Since I receive 5.5KW in my current configuration, would it be safe to add another 1.5kw to the Growatt MPPT's? I would expect the MPPT's to clip the extra amperage if I go beyond the 7KW allotted (120amps). Is that a reasonable expectation? Obviously not exceeding the 250V to the MPPT's.

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Also, I have my g4ll batteries connected to the growattt BMS service. I am just waiting for the Growatt WiFi dongle.

Thanks!~

 

[Jgb3]

How many AH of battery do you have? If I looked at the right one they are 100ah each that inverter says it requires 400ah minimum on the battery. May want to put that on the list I think it can damage the battery if it’s to small

 

[NewGuyNoob]

How many AH of battery do you have? If I looked at the right one they are 100ah each that inverter says it requires 400ah minimum on the battery. May want to put that on the list I think it can damage the battery if it’s to small

Hey!

I currently have 500ah in total. I have 5 48v Gyll batteries. I need one more to make a set of 6 in their battery cage that I bought. I enjoy the simplicity of their setup the most.

I would like to create another 30kwh in prismatic 280ah cells

 

[MrM1]

Nice... When I get the inverter I need to pm you guess for tips. (this ain't my first rodeo so I'm not lookin for hand holdin just ideas on planning)

 

[Rocketman]

Your panels may deliver too high of voltage. 47.8 open circuit *5s is 239 volts - when it gets cold they get more efficient- so the voltage goes up. (I don’t know the formula to figure it out - but it is somewhere on this site - possibly on the spec sheet for your panels).

Research item - what happens to your Growatt if the voltage goes over 250v this winter?
Does it get fried? At exactly the wrong time?
Or does it just stop charging until the volts drop.

With your long run of cable - it may not be an issue.

 

[Hedges]

With your long run of cable - it may not be an issue.

Long cable run doesn't reduce Voc, only Vmp.
So it won't help keep PV within max Vinput tolerated by SCC.
It can bump into minimum MPPT voltage.

Unless you sharpen your pencil by using record cold temperature at your location, and temperature coefficient of Voc for panels, make sure SCC can tolerate a voltage at least 16% higher than nominal Voc of PV (That comes from -15 degrees C being 40 degrees below 25 degrees nominal, and -0.4%/degree temperature coefficient).
That means for 250V max input, Voc of PV string shouldn't exceed 215V. Panels have 47.8 Voc, so 4s strings.

You can connects several strings in parallel, and each string can have different orientation. With multiple orientations (like 10:00 AM and 4:00 PM sun for 90 degree angle between them), peak output will be 0.7 times as high but production hours are extended.

7400W of panels and 10kW of batteries, that could be 0.74C charge rate. What do the batteries accept? If 0.5C, SCC should be programmed to limit to 5kW (or less.) The multiple orientations of panels will help avoid clipping production.

Even if batteries accept 0.5C, that is only around nominal 25 degree temperatures. If yours can get much colder (or hotter), not only do you need low-temperature disconnect to protect the batteries, but you should also turn down the charge current to whatever is acceptable at the temperature extremes where charging is permitted. It isn't a rectangular limit, full current at all temperatures above freezing. It is a curve that tapers down to zero.

 

[120vjohn]

LTO accepts far more than 0.5c I have installed 10kwh of LTO cell 110 cell of 40Ah 55s-2p 120v nominal, good if you catch sun briefly, can charge fast and fill your balley.
For LTO 2c is no problem far below freezing.

 

[alvirtuoso]

Max Open Circuit Voltage Calculator:

Calculation Form

Maximum open circuit voltage calculator

I'm posting this in a thread here since it might be useful for people. Please keep in mind that the below calculator contains bugs and doesn't do error checking - it's literally been 5 minutes to put together. Ok, so what does it do? It calculates the maximum open circuit voltage you would see...

diysolarforum.com

 

[kromc5]

If you have any loads over 5400w, I would double the 2/0 cabling which is what I did. Solar asistant is great an using it for two 12k inverters, there is a free open source as well, but I will need to find the link.

 

[Ironman]

You can over panel with Watts, but not Voltage. I would only string with 2 panels because you need headroom for cold winter days when the voltage spikes up. Max voltage is 146 for the 12000T
I have 20 panels in 10 strings. 5 strings feed one charge controller and 5 feed the other.

 

[MrM1]

You can over panel with Watts, but not Voltage. I would only string with 2 panels because you need headroom for cold winter days when the voltage spikes up. Max voltage is 146 for the 12000T
I have 20 panels in 10 strings. 5 strings feed one charge controller and 5 feed the other.

I think he has the 250vdc 12kw Growatt. So 4s should be fine.

But there seems to be a mixed response as to if you can overpanel the Growatt 12kw. I default to @kromc5 for that experience.

 

[Solar Newbee]

Question on another note on the Growatt 12K Inverter. In wiring up this inverter to a breaker panel/sub panel for AC power, from the AC output when wiring for 240 volt, do you wire H1, H2, and the N/ground or not to the terminal in the sub panel/breaker panel? I looked at the user manual, and it show just the H1 and H2 to get 240 volt. For 120 volt it is either H1 or H2 with just the N/ground to a sub panel for 120 volt. Can someone clarify this for me. Thanks

 

[kromc5]

Sent growatt a long email today with questions on paneling and providing pdfs on panel stats. I provided several scenarios for wattage/current and what is important. Due to the serial numbers, they are pushing me back to the seller but I asked if they could help.

 

[kromc5]

Question on another note on the Growatt 12K Inverter. In wiring up this inverter to a breaker panel/sub panel for AC power, from the AC output when wiring for 240 volt, do you wire H1, H2, and the N/ground or not to the terminal in the sub panel/breaker panel? I looked at the user manual, and it show just the H1 and H2 to get 240 volt. For 120 volt it is either H1 or H2 with just the N/ground to a sub panel for 120 volt. Can someone clarify this for me. Thanks

If 240 you need to hook h1/h2, plus N and ground to the breaker panel.

 

[MrM1]

Due to the serial numbers, they are pushing me back to the seller but I asked if they could help.

Serial numbers? Because the units were too old? Or bc they were sold in the US? So they were unwilling to help?

 

[Brett V]

Sent growatt a long email today with questions on paneling and providing pdfs on panel stats. I provided several scenarios for wattage/current and what is important. Due to the serial numbers, they are pushing me back to the seller but I asked if they could help.

I think that's fair. They'll help with a warranty issue or equipment problem but it's not their job to help plan your system for you.

 

[Zwy]

You can over panel with Watts, but not Voltage. I would only string with 2 panels because you need headroom for cold winter days when the voltage spikes up. Max voltage is 146 for the 12000T
I have 20 panels in 10 strings. 5 strings feed one charge controller and 5 feed the other.

I'd keep PV input for the GW 12K under 7000 watts total, not for each half of the inputs. If you want more PV input, I highly recommend adding another SCC seperate from the GW. With the 20 x 72cell 370W Rene Sola Panels you would probably be fine on wattage but I highly recommend calculating VOC with the temp coefficent as Hedges states.

 

[kromc5]

I think that's fair. They'll help with a warranty issue or equipment problem but it's not their job to help plan your system for you.

I have already built my system completely but I keep getting different information on panels allowed for their products. My hope is the manufacture can clear up the confusion.

 

[kromc5]

Serial numbers? Because the units were too old? Or bc they were sold in the US? So they were unwilling to help?

They always ask for the serial numbers when you contact them. We will just have to wait and see if they can provide exact panels allowed.

 

[kromc5]

I got a response from Growatt and now very fustrated I was way oversold on panels. I was told 2 strings of 3 two weeks ago, last week 4 strings of three. Growatt is saying I can only hookup 3 panels per input.

screenshot 669 — Postimages

postimg.cc

 

[MrM1]

Growatt is saying I can only hookup 3 panels per input.

screenshot 669 — Postimages

postimg.cc

Unless I am misunderstanding something, the message you posted from grow it says you can use 9 panels. In a 3s 3p configuration.

That would be 3465 w with your 385w panels, and 122 Voc. That is pretty much sitting right exactly on the spec sheet limits of 3500 watts and 145 V DC

 

[MrM1]

While this does not match any information we have been told from vendors and sellers, it does match the specs, and it seems to be what the manufacturer has designed for. Disappointing but at least gives some Direction

 

[kromc5]

Unless I am misunderstanding something, the message you posted from grow it says you can use 9 panels. In a 3s 3p configuration.

That would be 3465 w with your 385w panels, and 122 Voc. That is pretty much sitting right exactly on the spec sheet limits of 3500 watts and 145 V DC

Unless I am misunderstanding something, the message you posted from grow it says you can use 9 panels. In a 3s 3p configuration.

That would be 3465 w with your 385w panels, and 122 Voc. That is pretty much sitting right exactly on the spec sheet limits of 3500 watts and 145 V DC

That was my mistake forgot to add the 3p, its been a long day. I have to figure out how to pull a lot more wires.

 

[Zwy]

Unless I am misunderstanding something, the message you posted from grow it says you can use 9 panels. In a 3s 3p configuration.

That would be 3465 w with your 385w panels, and 122 Voc. That is pretty much sitting right exactly on the spec sheet limits of 3500 watts and 145 V DC

That answers that question doesn't it? No more than 3500w per input with a total of 7000w.

If I had ordered the GW 12Kw, I would have to add another SCC for my panels. With the LV6548 in tandem, I can have PV input of 4000w per input for a total of 16Kw of PV input. With my 530w panels, I can only go 4S per input as VOC is 49.65 and it gets very cold here. If I ever do a 2nd array, I think I'll put the 530's on a seperate SCC and run 385w panels with a VOC around 40. That would get me closer to the 4000w limit and still stay under 250V PV max voltage.

The newer versions of the GW 12Kw are 250V max PV input, not the 145V Ian has on his website. Sig Solar has the right specs. https://shop.signaturesolar.us/products/12kw-48w-240vac-120a-off-grid-inverter-by-growatt

 

[markansas]

I got a response from Growatt and now very fustrated I was way oversold on panels. I was told 2 strings of 3 two weeks ago, last week 4 strings of three. Growatt is saying I can only hookup 3 panels per input.

screenshot 669 — Postimages

postimg.cc

now from what i see is that they dont want you to go over 150volt dc input of the panels. growatt made two versions of this one rated at 150v dc and one at 250v dc.. check and see what you have please and lets go from there.. if you have the 250v dc input you might be able to redo your strands. if i am using the right words.. warning warning do not go over the voltage recommended..
mine