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Intermittent power loss Growatt MIN TL XH US

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saenns

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Oct 27, 2021
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There are regularly large drops in power throughout the day. PV current drops, but PV voltage remains high. Confirmed by video recording that there are no clouds. Specifically at 3:27PM when power dropped the most.

The power loss is weakly correlated with derating mode 4 (Fac) and derating mode 20 (not documented?). Inverter temps are getting well into the 60C+ but it's less correlated and I don't see any derating mode 5 or 6 (Tinv, Tboost) in the logs. Similarly, weak correlation with AFCI strength/status.


Any ideas for how to debug this? I may try another GRID setting such as IEEE (currently Rule 21), or disabling frequency derating. I may install Solar Assistant in search of more information.
Screenshot 2024-06-22 at 7.29.09 AM.pngScreenshot 2024-06-22 at 7.29.16 AM.pngScreenshot 2024-06-22 at 7.49.40 AM.png
Screenshot 2024-06-22 at 7.49.57 AM.png
 

Attachments

  • growatt min series.xlsx.zip
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Can you plot against frequency?

Rule 21 is very strict so at the very least try a different one.
 
Good idea. But Fac was 60 the entire day except for one measurement at 59.9 and it's not near any of the power drops. Maybe SolarAssistant will provide more precision? I will try IEEE
 
saenns said:
Good idea. But Fac was 60 the entire day except for one measurement at 59.9 and it's not near any of the power drops. Maybe SolarAssistant will provide more precision? I will try IEEE
Click to expand...
How are you measuring fac
 
saenns said:
Fac measured using the Growatt Shinephone website, "History Data" function. Which I suspect is register 37 on mobdus.

Click to expand...

I don't think it's all that accurate. Solar assistant shows 60hz across the board(pulling from growatt inverter) but the actual frequency varies a lot when I measurevut a different way.

Did you try ieee1547?
 
saenns said:
There are regularly large drops in power throughout the day. PV current drops, but PV voltage remains high. Confirmed by video recording that there are no clouds. Specifically at 3:27PM when power dropped the most.

The power loss is weakly correlated with derating mode 4 (Fac) and derating mode 20 (not documented?). Inverter temps are getting well into the 60C+ but it's less correlated and I don't see any derating mode 5 or 6 (Tinv, Tboost) in the logs. Similarly, weak correlation with AFCI strength/status.


Any ideas for how to debug this? I may try another GRID setting such as IEEE (currently Rule 21), or disabling frequency derating. I may install Solar Assistant in search of more information.
View attachment 223808View attachment 223807View attachment 223818
View attachment 223816
Click to expand...
Let’s start at the beginning:
1. Describe system. Including where inverter is installed and what the ambient temperature is in that location. Including when it was first connected and what other problems might have occurred before now.
2. When did you first notice the problem?
3. Have you tried turning Afci off?
4. Are you using the RSD device?
5. Picture of the wire box would be good, close enough to see wiring.
 
> I don't think it's all that accurate. Solar assistant shows 60hz across the board(pulling from growatt inverter) but the actual frequency varies a lot when I measurevut a different way.

Good to know, thank you. Is there a better way to measure it over time?

> Did you try ieee1547?
Yes, it improved a lot but still not perfect. Wish I knew what is Derating Mode 20.
Screenshot 2024-06-23 at 7.54.45 AM.png

> 1. Describe system. Including where inverter is installed and what the ambient temperature is in that location. Including when it was first connected and what other problems might have occurred before now.

It was installed May 2023, PTO granted March 2024. I believe it's been happening the whole time, but before I assumed it was clouds and limit export made it difficult to detect. Installed in Bay Area, 90% shade, daytime highs have been around 80f.

> 2. When did you first notice the problem?

I forget exactly. Lets say since PTO was granted and export limit was disabled

>3. Have you tried turning Afci off?
No, will try that today.

>4. Are you using the RSD device?
Yes, Tigo TSA-4-2F

> 5. Picture of the wire box would be good, close enough to see wiring.

IMG_0049.jpg
 
saenns said:
> I don't think it's all that accurate. Solar assistant shows 60hz across the board(pulling from growatt inverter) but the actual frequency varies a lot when I measurevut a different way.

Good to know, thank you. Is there a better way to measure it over time?

> Did you try ieee1547?
Yes, it improved a lot but still not perfect. Wish I knew what is Derating Mode 20.
Click to expand...

Good that it's better.

Try turning afci off as @MajicDiver suggested
If that doesn't fix it I'll have some ideas of how you can fix it if it's just frequency.

Do you have an installer log in for shinetools?

I track mine with an iotawatt. I also have solar assistant and a CT meter installed and that also shows accurate frequency.

saenns said:
View attachment 224038

> 1. Describe system. Including where inverter is installed and what the ambient temperature is in that location. Including when it was first connected and what other problems might have occurred before now.

It was installed May 2023, PTO granted March 2024. I believe it's been happening the whole time, but before I assumed it was clouds and limit export made it difficult to detect. Installed in Bay Area, 90% shade, daytime highs have been around 80f.

> 2. When did you first notice the problem?

I forget exactly. Lets say since PTO was granted and export limit was disabled

>3. Have you tried turning Afci off?
No, will try that today.

>4. Are you using the RSD device?
Yes, Tigo TSA-4-2F

> 5. Picture of the wire box would be good, close enough to see wiring.

View attachment 224042
Click to expand...
 
Thanks for your help, 1201. I have the installer login if that's what you mean. I'll update tomorrow with the results from disabling AFCI.
 
saenns said:
Thanks for your help, 1201. I have the installer login if that's what you mean. I'll update tomorrow with the results from disabling AFCI.
Click to expand...
What you might try as well today, since you have the installer login.

Under grid code, frequency watt,

Change frequency watt derate slope to 100%, default is 33%
Change frequency watt derate point to 60.05, default is 60.03
 
Looks like there's a separate setting for FrequencyHigh* and Under Frequency*. I just changed the settings for FrequencyHigh. Does it look right?
Screenshot 2024-06-23 at 9.23.35 AM.png
 
saenns said:
Looks like there's a separate setting for FrequencyHigh* and Under Frequency*. I just changed the settings for FrequencyHigh. Does it look right?
View attachment 224069
Click to expand...
Yes, looks good.

Do you have a multimeter? Maybe you could measure your frequency for a couple of minutes and see if you see any fluctuations.

This is what mine looks like over the last 30 mins

Screenshot_20240623-113000.png
 
saenns said:
Picture of the wire box would be good, close enough to see wiring.
Click to expand...
It appears you have a battery, that opens up several possible issues to be considered, questions:
1. What battery and its capacity?
2. What are your battery settings?
3. Depending on you settings and other things - for example if you have max charge limited to less than 100%, you could be seeing momentary battery charging. Once the battery hits 100% inverter won’t try to charge it till it reaches 95%, if you have it limited to 99% it will charge every time the inverter sees it go below 99%. You would not notice unless you were using all your PV to make ac power.
 
saenns said:
I don't think it's all that accurate. Solar assistant shows 60hz across the board(pulling from growatt inverter) but the actual frequency varies a lot when I measurevut a different way.
Click to expand...
Which frequency in solar Assistant? The is a grid frequency and a off grid frequency (backup output). For these inverters the off grid frequency does not work, read 60hz all the time, both in the app and the modbus register Solar Assistant uses. For my inverters the grid frequency does work and is accurate in solar Assistant.
 
saenns said:
Picture of the wire box would be good, close enough to see wiring.
Click to expand...
It appears you are using the backup out put. Is it with a ATS or a critical loads panel that always draws power?

Also, if you are on grid like you are, ac coupling needs to be turned of, otherwise I believe the inverter will respond very rapidly to tiny changes in grid frequency. Can you send a screenshot of the quick settings screen in the app? See example attached, we off grid and ac coupled, you should have it off.
 

Attachments

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Thank you both for your generous and expert help.

> Do you have a multimeter? Maybe you could measure your frequency for a couple of minutes and see if you see any fluctuations.

Yes, great idea. Will test later.

> Where are you seeing the derating mode at? Can you send a screenshot?

It's not visible in the HistoryData like I thought, you have to export to excel. Column BI in the sheet attached.
Screenshot 2024-06-23 at 11.57.18 AM.png


> 1. What battery and its capacity?
LG RESU 10H Prime, 10Wkh, 5KW

> 2. What are your battery settings?
Solar-only backup. max charge 100. There wasn't much charging yesterday, column DA

> It appears you are using the backup out put. Is it with a ATS or a critical loads panel that always draws power?
Backup output is connected to ATS

> Also, if you are on grid like you are, ac coupling needs to be turned of, otherwise I believe the inverter will respond very rapidly to tiny changes in grid frequency

Great idea but it was already turned off.
Screenshot 2024-06-23 at 12.05.38 PM.png
 

Attachments

  • growatt min series 2.xlsx.zip
    191.8 KB · Views: 1
saenns said:
Backup output is connected to ATS
Click to expand...
I assume you also have an auto transformer? I’m assuming the auto transformer is not powered unless the ATS transfers to backup? In other words, your auto transformer is not between the ATS backup input and the inverter backup output?
 
Yes the ATS has a transformer it's ATS11400T-US. The transformer is after the ATS backup input. However, the transformer is still in use even when powered by grid. Bonding N to Ground in the critical load panel as the ATS does not have a Neutral input, so otherwise the Neutral output is isolated from Ground. Wiring diagram attached.

Screenshot 2024-06-23 at 12.53.08 PM.png
Screenshot 2024-06-23 at 1.00.20 PM.png

​
 
saenns said:
> 2. What are your battery settings?
Solar-only backup. max charge 100. There wasn't much charging yesterday, column DA
Click to expand...
The reason I’m asking is what your plots show and what you describe are EXACTLY what I see on my system when ac coupled inverter very briefly charges it’s battery and then stops. I’m talking about a few seconds. For reasons I will not go into, this cycling can persist for anywhere from a couple of minutes to 1/2 hour when the battery is almost at 100% and the grid forming inverter is asking for more power than the ac coulpled inverter can produce. Perhaps your inverter is not using a deadband like it’s supposed to and is charging every time it sees the battery drop to anything less than 100%. Or perhaps your lg-to-inverter comm’s are flaky and sometimes the inverter is briefly getting incorrect battery SOC. Might try disconnect battery a few days and see if problems go away or not - then worry about what all can cause it if it goes away.
 
@saenns

In the graphs the dropouts don't seem to be happening in the morning- I wonder if this could be temperature related.


Did this happen in winter?

It would also give some support to what @MajicDiver is thinking, maybe this only happens when the battery is full?
 
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