Error Code 28 - 10 Minute Average Grid Voltage Fault

[Ian345]

Hoping for any advice,

We have a Fox H1 3.7Kw Inverter, 3x Fox ESS 4.03 batteries and 10x Trina Vertex 425W PV. Installed for about 4 weeks now.

All seems to be working fine - Apart from in the last few days, Our Inverter has stopped with the Error Code 28 - 10 Minute Average Grid Voltage Fault
. After 15 to 45 minutes, the Inverter restarts and everything is happy again.

Looking at the data on the FoxESScloud website - It seems to correlate with the 'RVolt' going above 250v (max is about 252v).

Am I right in assuming that this is the grid voltage going too high, the Inverter not being happy and there is nothing we can do about it? Or - Is there something that can be done - by adjusting an Inverter setting to allow above 250v?

Has anyone else come across this before?

Any advice/help appreciated.
Ian

[Dave Foster]

Ok slightly long answer - your DNO (distribution network operator) is required to keep the grid voltage in domestic homes within -6/+10% of 230v so the maximum should be 253v.

The Foxess inverter will measure a little higher when your solar output is high and there is a safety limit set at 253v to stop it going too high. If you contact your DNO they should come out quickly and check the voltage and they may leave some monitoring equipment behind. If they decide it's too high they'll turn it down and the problem solved.
But sometimes they will say it's 'just' within limits and leave you to sort it out with your installer.

I would suggest a call to both your DNO and your installer, tell your DNO the voltage is too high and tell your installer the inverter is shutting down with a Vac 10 minute average alarm - it is possible to change the safety limit on the inverter but it is best done after your DNO has checked the voltages.

[Ian345]

Hi Dave,
Thank you so much for your quick reply.
We will do as you suggested.
kind regards
Ian

[Ian345]

Update.....

Managed to get our DNO, SSEN, into action.

They will be installing a voltage monitor - to check the grid voltage. he recorded 244v this morning. However, the guy said that as we were reporting less than the maximum 253v - they might not do anything about it (the highest our Inverter has recorded is 252.2v).

Have contacted our FoxESS Installer, to see if the Inverter 250v trip limit can be upped a bit.

However - When the SSEN guy looked inside our outside meter box, he noticed that our EV RCD box is in there and has told us to get it moved. To compound this, our Solar PV installer added two Surge Protectors in the spare ways in the same EV RCD Box. Damn.

[Dave Foster]

Ouch, hopefully moving won't be too much of a problem

It sounds like you are close to the limit but perhaps not getting over 253v at the main fuse, the inverter will read a bit higher as it's pushing power back into the grid - the 10 min average limit is normally set to 253v so I suspect you're getting over this just not for long enough to record on the website.

If you get stuck with your installer not wanting to adjust it, let me know and i'll guide you through which setting to change.

[davidiaincraig]

I have been getting multiple of these every day, and not just during daylight. The inverter was reporting RVolt at around 254V for almost an hour at 1.30am two nights ago. I have a H1 5.0 inverter.
I contacted my DNO, and they asked me to confirm the voltage with my installer. The graph from foxess shows the voltage fairly consistent at 250V or above. My only other data point is that I have a UPS in my office that shows the grid voltage. It normally shows only 216V when there's no solar generation and jumps to 250V when there is. Is there a configuration setting which can make the inverter misread the level?
The installer is bringing the batteries in a couple of weeks, but is like to know more before then

Thanks

Dave

[Ian345]

Latest update....

DNO measured our voltage and reported that - Yes, it 'spikes' over 250v but is within limits and therefore will do nothing about it.

Our inverter has been tripped for 3 hours this morning.

No luck yet from FoxESS or our supplier on how to adjust the Inverter (H1-3.7-E) to trip at a higher limit than 250v.

Therefore, Dave - If you are able to provide the detailed notes on how to change the Inverter limits, we would be so very grateful.

Regards
Ian

[Ian345]

Update - It looks like the setting is covered by the third item in the file 'Advanced-configuration.pdf' - available in the FoxESS downloads section of their website.

Have asked our installer to do the change (needs installer login and not user, by the looks of things).

Hoping that it works

[Dave Foster]

Hi Ian,

Sorry for the delay, i've only just got back from holiday.

If you still want to make the change, you can do so from the inverter front panel (as long as you have the PIN number to access, the default is 0,0,0,0)

From what you have said it's looking like 254v is the occasional highest you see, so we will go just above that for now and see if that resolves it.

Go to the inverter front panel,

Select Settings, the pin is 0[enter], 0[enter], 0[enter], 0[enter]
Scroll down to On-Grid and press enter
Scroll down to the bottom of this menu and select the item 'Grid Para'
Scroll down to the bottom of this menu and select the item 'Vac 10min Avg'
Change this to 255v and press enter to set it.

And that's it - the new 10 minute average voltage is 255v and hopefully that should stop it tripping out all the time.

[Ian345]

Hi Dave,

You are a superstar - Thank you very much.

Will give that a go.

Hope you had a great holiday
regards

[davidiaincraig]

The inverter was reporting RVolt at around 254V for almost an hour at 1.30am two nights ago. I have a H1 5.0 inverter.
I contacted my DNO, and they asked me to confirm the voltage with my installer. The graph from foxess shows the voltage fairly consistent at 250V or above.

I thought I'd give an update. My DNO (SP Energy) sent an engineer round, and he measured the voltage and then got hold of historical data from all the smart meters that are on the same line running from the substation. He said that they were all consistently high (252V). They monitored for a week, during which time it rose to 254V at times. They changed the transformer tapping at the substation and the result was a voltage drop of about 1% which brings everything back into line. Here's what the inverter saw whilst they were adjusting the voltage:

I've had no more alarms since.

Dave

[Dave Foster]

I've had no more alarms since.

Dave

Great result

[foxee]

Thank you for everyone in this thread esp Dave! Very much appreciated as I had the exact same thing which started a few days ago and got worse today. Google FTW as all the Chat AI bots did not have a solid answer.

My setting was set to 253v which I changed to 255 and fingers crossed the issue has not raised its ugly head again.

Select Settings, the pin is 0[enter], 0[enter], 0[enter], 0[enter]
Scroll down to On-Grid and press enter
Scroll down to the bottom of this menu and select the item 'Grid Para'
Scroll down to the bottom of this menu and select the item 'Vac 10min Avg'
Change this to 255v and press enter to set it.

And that's it - the new 10 minute average voltage is 255v and hopefully that should stop it tripping out all the time.

[Dave Foster]

Thank you for everyone in this thread esp Dave! Very much appreciated as I had the exact same thing which started a few days ago and got worse today. Google FTW as all the Chat AI bots did not have a solid answer.

My setting was set to 253v which I changed to 255 and fingers crossed the issue has not raised its ugly head again.

Nicely done

[maoh1]

Hi there. I have the same issues every day, sometime several times per day. But I don’t have this settings. What can I do?Inverter Model : H3-12.0-E

[DianeAliseMonique]

Hello, we have the same problem on H3-8-E but when we go into the menu it is totally different. Somebody an idea what to do?
Thank you.

[Dave Foster]

Hello, we have the same problem on H3-8-E but when we go into the menu it is totally different. Somebody an idea what to do?
Thank you.

On the latest H3, I believe it is found under the Safety menu.

Select Settings, the pin is 0[enter], 0[enter], 0[enter], 0[enter]
Scroll down to On-Grid and press enter
Scroll down to the bottom of this menu and select the item 'Safety'

Is there a menu item there called Safety Voltage Params ?

Alternatively call your installer or Foxess support, it can be set remotely.

[DianeAliseMonique]

Good morning Dave, thank you for the quick response!
When I follow the steps and go to Safety I don't find what you are saying.
I put some pictures off the menu.
I am gonna call the installer.

[Dave Foster]

Good morning Dave, thank you for the quick response!
When I follow the steps and go to Safety I don't find what you are saying.
I put some pictures off the menu.
I am gonna call the installer.

thanks for the photos, very helpful - it looks like the main safety voltage parameters are not available on your H3 from the inverter panel.

Good idea, your installer will be able to change the settings for you on-line.

[abdul.wasay98]

kindly tell me the way to change the Over voltage protection settings for the fox T10-G3 on grid inverter.

[Dave Foster]

kindly tell me the way to change the Over voltage protection settings for the fox T10-G3 on grid inverter.

I can't see that setting in the manual, if it is available as an advanced setting - probably best to email your installer, or to your local Foxess support team.

[SimonSays]

Thank you for everyone in this thread esp Dave! Very much appreciated as I had the exact same thing which started a few days ago and got worse today. Google FTW as all the Chat AI bots did not have a solid answer.

My setting was set to 253v which I changed to 255 and fingers crossed the issue has not raised its ugly head again.

Select Settings, the pin is 0[enter], 0[enter], 0[enter], 0[enter]
Scroll down to On-Grid and press enter
Scroll down to the bottom of this menu and select the item 'Grid Para'
Scroll down to the bottom of this menu and select the item 'Vac 10min Avg'
Change this to 255v and press enter to set it.

And that's it - the new 10 minute average voltage is 255v and hopefully that should stop it tripping out all the time.

Had a similar issue with the H1-3.7-E, ongoing for ages. Have adjusted to 255v as suggested, so hopefully that resolves this. I live fairly close to the Substation so not sure if that makes any major difference, but on the FoxESS console regularly see over 254v (most recent peak I've seen is 255.7v).

[Dave Foster]

Had a similar issue with the H1-3.7-E, ongoing for ages. Have adjusted to 255v as suggested, so hopefully that resolves this. I live fairly close to the Substation so not sure if that makes any major difference, but on the FoxESS console regularly see over 254v (most recent peak I've seen is 255.7v).

The closer to the substation it will be slightly worse and also if you have a lot of solar generation in the neighbourhood that will also affect it.

The inverter has to ‘compete’ with the grid when exporting so it will often read a volt or 2 higher than the measured voltage at your smart meter - so you might need to go a bit higher (~257V) on a sunny day - see how you get on

[SimonSays]

Had a similar issue with the H1-3.7-E, ongoing for ages. Have adjusted to 255v as suggested, so hopefully that resolves this. I live fairly close to the Substation so not sure if that makes any major difference, but on the FoxESS console regularly see over 254v (most recent peak I've seen is 255.7v).

The closer to the substation it will be slightly worse and also if you have a lot of solar generation in the neighbourhood that will also affect it.

The inverter has to ‘compete’ with the grid when exporting so it will often read a volt or 2 higher than the measured voltage at your smart meter - so you might need to go a bit higher (~257V) on a sunny day - see how you get on

Typically if it does go over 255v it seems to only be for 10-20mins, which I can live with. That being said the council is giving loads of people solar panels, so will need to wait and see.

Is there any risk from putting a value that is too high?

[Dave Foster]

Typically if it does go over 255v it seems to only be for 10-20mins, which I can live with. That being said the council is giving loads of people solar panels, so will need to wait and see.

Is there any risk from putting a value that is too high?

It’s a complicated answer - the DNO is supposed to ensure the grid voltage to your house doesn’t exceed 230V -6% / +10% and so the theoretical maximum is a sustained 253V measured at your smart meter - as mentioned your inverter would report a bit higher when it is exporting so you seeing an occasional 256V is reasonable, and probably means the actual grid voltage is within it’s range.

I’ve seen a property measure (peak) above 263V and there were no adverse reports from the neighbourhood, it was just the Zappi car charge and Inverter that were reporting the voltage as being outside of their operating range.
In that case the DNO lowered the tap on the local substation which saw the peak fall to around 256V so everything worked again but they said in general because of solar generation they are more prepared to tolerate higher peak voltage than one that is too low.