Growatt 3000 LVM possible inverter issues

[Repro]

I have been intensely engaged with my solar hobby for over a year, and I have learned a lot. I have made SOOOO many mistakes, and paid for them dearly. Maybe some of my other posts will save people from having the same problems.

I have a Growatt 3000 LVM 24V inverter. I have been so happy with it until recently. I may have pinpointed an issue I have been having. Just a quick overview of my system:

2000W array
Growatt 3000 LVM 24V
4 200AH LiFePO4 batteries (2S/2P) for 24V
AC input is on an isolated 20A circuit
AC output to a 6 space sub panel wired to four 20A outlets with breakers at the moment.

What am I running:
Two full size refrigerators
Front loader wash machine (ran 2-3 times/week)
Two 1.5 HP sump pumps (run for 5-7 seconds maybe twice a day)
One outlet in my garage for two battery tenders
It is my intention to install a switch to run my furnace in winter during outages (8A draw)

Problem: Since I installed the Growatt system, my refrigerator lights flicker badly when both fridges run at the same time, We have gone over the wiring multiple times, shortened the wiring runs as much as possible and have tried multiple configuration parameters on the Growatt. I have called the dealer for support, did a factory reset and reconfigured. The only explanation was that the two refrigerators might be causing fluctuations. Another suggestion was to change the wattage of light bulb (It has LED's). In the short time the system has been running, my upstairs one year old refrigerator is now broken. You could hear the compressor running funny when the lights flickered. It is just my opinion, but I think the Growatt is the culprit.

The load on the inverter was ridiculously low. Seldom did it see over 1000W at one given time during the course of the day. See chart attached. So why can't the inverter in the Growatt handle this? I have ran these two refrigerators on two different portable units that I built with no flickering or issues for weeks at a time doing tests. One has a Ginadel 2200W inverter, and the other has a GoPower Industrial 1500W inverter (both pure sine wave). Never once did I experience flickering or the compressors running strangely.

Can anyone shed some light on this? I do not want to sound so negative, but I have ran into so many issues over the course of installing this Growatt system from zoning, permitting, inspections and now this, that I am about ready to pack it in. Total frustration!!!!!!!!! I hope that an answer can be found. If I am right, stay away from Growatt. Another expensive mistake that cost me a fridge, and now another inverter investment.

 

[John Frum]

First question:
Have you verified that the inverter output is 120VAC at 60hz?

Second question:
Is the inverter output reasonably sinusoidal?

Third question:
Does the problem go away when you are in bypass mode?

 

[Hendo7]

scary as i plan on running 3 refrigerator's on my growatt (not installed yet waiting on batteries)
this is the first time i have heard anything bad about growatt
hope you get it sorted,i will be paying attention to this

 

[Repro]

First question:
Have you verified that the inverter output is 120VAC at 60hz?

Second question:
Is the inverter output reasonably sinusoidal?

Third question:
Does the problem go away when you are in bypass mode?

Yes, the inverter is set to and puts out 120V @ 60Hz. That was verified by a Kill-A Watt and a no name device like a Kill-A-Watt. The Kill-A-Watt shows fluctuation in voltage and the frequency varies as well when the flickering takes place.

I do not have an oscilloscope to verify the stability of the sine wave.

Yes, the problem does disappear when in bypass. That is why I am 100% convinced (opinion again) that the inverter is the issue. This is likely to be acceptable as the dealer told me to just run one refrigerator. He also suggested that I install an AC line filters (2) to clean up the noise created by the fridge inductor motors. I may try that, but once again, more money to see if it works. If it doesn't, out the window. I must say that the dealer is really trying and is very nice about the whole thing.

 

[John Frum]

Won't the induction noise be there regardless of the power source?
Does a big transformer act like some kind of damper or dry load?
Do you have a generator or another inverter you can swap in for a test?

 

[Prefersdirt]

I kept 2 freezers on mine for several weeks. Now only one is there (moved things around - gotta get everything on it soon). My biggest issue was trying the powersaver - it nearly cost me a freezer full of food as it never turned on. Good thing I monitor my freezers closely.

Can the dealer send you another unit to try? Might just be a bad unit.

 

[Repro]

Won't the induction noise be there regardless of the power source?
Does a big transformer act like some kind of damper or dry load?
Do you have a generator or another inverter you can swap in for a test?

To my understanding, if the fridge inductor motors are feeding back with interference or noise, the filters may resolve the issue. The problem only exists when both fridges are running at the same time. For some reason, the Growatt inverter cannot deal with two inductor motor loads at the same time.

I stated above, I used a 2200W Giandel inverter, and a GoPower 1500W industrial inverter as well. Neither of these inverters exhibited these issues. Speaking of generator, I have a Honda EU3000is inverter generator and ran both fridges on it for several hours, several different times with no flickering or compressor issues. The dealer agrees with me that the issue may be with the Growatt 3000 LVM 24V inverter. He is skeptical about swapping it out and have the same issue. We may be able to work out a pro rated refund if I am lucky.

If anyone has the same Growatt inverter, and you have two refrigerator/freezer combinations, please try both out and see if you have the same issue.

Thank you for all for any feedback.

 

[Repro]

I kept 2 freezers on mine for several weeks. Now only one is there (moved things around - gotta get everything on it soon). My biggest issue was trying the powersaver - it nearly cost me a freezer full of food as it never turned on. Good thing I monitor my freezers closely.

Can the dealer send you another unit to try? Might just be a bad unit.

The power saver did not work for me as well. When activated and the unit went into power save mode, it never woke up when a load was applied. The power saver mode can also exhibit light flickering when activated. I turned power saver off the first day of testing it out.

 

[Joe BoyKey]

I have the Growatt SPF-6000T-DVM running Big freezer, small Refrig, pc with 2 monitors, stereo, 1 ton 240v mini-split, and all garage lights, around 400 to 1600 watts. had similar issue before fixing the "can only be 1 Neutral to ground point" So the feed to your inverter from the house panel should be 4 wire - L1, L2, Neutral, and Ground - the single point should only be at the house panel, never in a sub panel, see house panel on pic, Joe.

 

[John Frum]

Darn...
I was just going to inquire about N/G bond but my POS computer tanked.

 

[Repro]

I looked at your diagram. So you are saying that the ground provided by my house's panel that supplies AC to the Growatt should the source of my ground? I currently have my Growatt sub box providing ground to two 8ft rods we put in just for the Growatt. Your diagram tells me that the isolated 20A AC line to my Growatt would provide the ground and be branched out to my sub panel. Please let me know if this is the solution. That would be too easy. I am getting my hopes up.

I have an older house and do not have a 4 wire electrical system with a neutral.

 

[John Frum]

This is more about the N/B bond and less about the dirt circuit.
You need to have one and only one bond between neutral and ground in your system.
Typically that is done at the service entrance by a green screw.
The growatt may be bonding neutral and ground as well.
And that can cause ground loops.
It can also be a life saftey and fire saftey issue.

 

[Joe BoyKey]

Correct just like the diagram, you should have 1 ground rod at house panel and your 2 rods to solar panels and panel structure. Ground loops can be tricky depending on soil, there is a diagram at watts247 I used to get mine right. Ian helped of course. Dc (panels) and ac should have separate grounds and only 1 neutral to ground bond at your house panel, Joe.

 

[Repro]

Got it. I have two grounds. One at the AC in and the other at my sub panels. Both grounds are completely separate causing a ground loop. I am heading down now to try it out.. I am going to disconnect the grounding system we installed and ground directly from the ground source at my AC input. Thanks! I will get back at you.

 

[Repro]

Correct just like the diagram, you should have 1 ground rod at house panel and your 2 rods to solar panels and panel structure. Ground loops can be tricky depending on soil, there is a diagram at watts247 I used to get mine right. Ian helped of course. Dc (panels) and ac should have separate grounds and only 1 neutral to ground bond at your house panel, Joe.

I already installed rods for the panels and will be installing a combiner box with a lightning arrestor at the array when my zoning approval arrives.

This sounds great, you learn everyday! Massive help. I will get back at you if this resolves my issue. I am confident you got it.

 

[John Frum]

Got it. I have two grounds. One at the AC in and the other at my sub panels. Both grounds are completely separate causing a ground loop. I am heading down now to try it out.. I am going to disconnect the grounding system we installed and ground directly from the ground source at my AC input. Thanks! I will get back at you.

This is very likely nothing to do with the rods in the ground.
Its very likely about having multiple bonds between neutral and ground.
You can isolate your panels for a test.
I guess I'll just move along.

 

[Joe BoyKey]

This is a Growatt inverter in the pics.

Wiki-FAQ – Watts247 Wholesale

watts247.com

 

[Repro]

It took all of 5 minutes. I never would have thought that the AC input ground would be all I needed. I thought it was isolated. The quick verification was to disconnect my solar box ground, did a continuity test on the grounding posts AC in /out on the Growatt. Just to make sure, I did a continuity test on the grounding post of one of my houses outlets with grid power, and the ground posts of an outlet coming from the Growatt inverter. BEEEEEEEEEP! Sound of joy!

I turned the system back on, cranked the temp lower on the fridges to get them running and no more flickering. Thank you so much Joe. I already called the dealer to inform him and I can keep my Growatt.

 

[Joe BoyKey]

Your welcome, pay it forward, many people helped me here and Naws.

 

[Repro]

Sorry Joe to disappoint you, but I spoke (posted) too soon. I still have the issue. I tested it with my fridge and an upright freezer we seldom use. The lights in the fridge are flickering badly, and I can hear the compressor motor fluctuating with the flickering. I unplugged the freezer to avoid problems, and the flickering stopped. I am now back to the Growatt inverter. Any other possibilities?