Hello guys,

 

I have the inverter Axpert VIII twin 6k (off-grid) connected to the main house load (with solar panels and batteries)

Prior to that, I had a backup ups for my office room installed since 2 years, but after installing the solar inverter, the UPS is going crazy (please check the video link from my google drive: UPS problem video)

The ups going into battery mode every 10 seconds and start beeping then goes back online. I have noticed that this only happens when the solar inverter(Axpert) is taking load from PV input, but not when it is on battery mode at night. And I have noticed that Axpert invert AC1 Output Voltage(V) is not stable, it suddenly drops to 216v then goes back to 230v.

Perhaps this is a voltage fluctuation issue from Axpert or sinewave issue, can anyone help please? And why this is only happening during sun hours?

 

Thank you

 

 

Edited June 20, 20224 yr by Guitaret

thank you @stokfor your input, and yes you are probably right, the ups is working perfectly fine (despite the solar installer company telling me they don't work well with each other and that I should remove it)

 

This only happens when on PV, works fine on bypass and on battery mode after sun hours. My ups keeps beeping every 10-20 seconds, perhaps it beeps less when I increase the house load.

I have all the data of the inverter on an excel sheet, it has a WIFI module. Another weird behavior as well, my inverter keeps charging/discharging the battery without any good reason (only during pv hours) even when it is 100% and I am using very low house load.

What do you think? Anything wrong in my installation? or the inverter has issues?
Do you want me to send the data dump?

 

Thanks a bunch

Edited June 20, 20224 yr by Guitaret

On 2022/06/20 at 7:57 PM, Guitaret said:

I have the inverter Axpert VIII twin 6k

I think that there must be some typos there. Is it a VM III 5 kW?

What is twin about it? VM models can't be paralleled. [ Edit: I did not know about Twin models (two output ports) at the time of this post. Sigh. ]

Perhaps it's a pair of Axpert MKS IIIs paralleled?

What size battery do you have? If it's too small for your inverter(s), that could explain the wild dip in AC voltage, with consequent reaction from the UPS.

Edited December 23, 20232 yr by Coulomb

7 minutes ago, Coulomb said:

I think that there must be some typos there. Is it a VM III 5 kW?

What is twin about it? VM models can't be paralleled.

Perhaps it's a pait of Axpert MKS IIIs paralleled?

What size battery do you have? If it's too small for your inverter(s), that could explain the wild dip in AC voltage, with consequent reaction from the UPS.

It is a VIII 6KW twin, meaning it does have 2 outputs for different priorities load.

Ex: output 1: house load, output 2: emergency light and you can program it to switch off output 1 first when on low battery. I think it is a new model.

 

My batteries: 4 x 12v (200ah) gel.

 

What do you think?

 

 

 

 

3 hours ago, stok said:

yes send the data, maybe we can learn something...

can you also post a picture of the inverter nameplate on the side with all the inverter specs and info?

 

Thank you.
Below is the picture, and this is the Inverter: https://voltronicpower.com/en-US/Company/News/148   (the orange one on the right,  VIII twin)

Attached is yesterday's data, I highlighted in red when the voltage drops below 220, and when battery is discharging even though battery is 100% & I have good PV input and low load. And I have upload a video of the inverter voltage fluctuation issue, you can see sudden droppage (happens very often).

 

 

energy-storage-container-June-20-2022.xlsx

Edited June 21, 20224 yr by Guitaret

Ok, so this is a pretty recent model; it's not integrated properly into Voltronic Power's web site. But that's happened before.

I had not heard of this model, or even of the twin output feature. However, as soon as I saw the colour and pattern, I noticed that it looked like a PowMr model. PowMr are known clone manufacturers, or at least they were. Perhaps the lawyers have forced them to become legitimate resellers now. I can't imagine that they can clone a new inverter model that fast.

I'd say it's a teething problem with the firmware. Have you tried getting an update from your supplier?

As a point of interest, what is the brand?

2 hours ago, Coulomb said:

Ok, so this is a pretty recent model; it's not integrated properly into Voltronic Power's web site. But that's happened before.

I had not heard of this model, or even of the twin output feature. However, as soon as I saw the colour and pattern, I noticed that it looked like a PowMr model. PowMr are known clone manufacturers, or at least they were. Perhaps the lawyers have forced them to become legitimate resellers now. I can't imagine that they can clone a new inverter model that fast.

I'd say it's a teething problem with the firmware. Have you tried getting an update from your supplier?

As a point of interest, what is the brand?

Heheh not sure about the PowMr thingy, apparently you know a lot about the behind the scenes business than me.

Update? You mean software update? And what is a teething problem?

On 2022/06/22 at 1:15 AM, Guitaret said:

You mean software update?

Firmware update, yes, in the form of a zip or rar file with a reflash tool and the firmware image.

On 2022/06/22 at 1:15 AM, Guitaret said:

And what is a teething problem?

Problems with new borns, in this case new inverter models. Some people say never buy version one of anything. New models don't have as many bugs fixed as more mature models.

@Coulomb thank you so much, the company said they will assist me in updating the software, currently waiting for their call (fingers crossed)

For testing, I did install one old-type incandescent light bulb and it confirmed to me that there is a voltage fluctuation issue in the house, apparently my voltmeter was not quick enough to detect that.

 

Now I am afraid something might happen to my home appliances.

All in all, I appreciate the helpful community here and I shall keep you posted if the issue is fixed.

Cheers

On 2022/06/20 at 2:49 PM, Guitaret said:

perhaps it beeps less when I increase the house load

Not an inverter engineer, but can share some anecdotal evidence from a few years ago.

I was commissioning some IT-type servers in a solar farm under construction before the grid tie-in was done. The site manager issued me a small diesel genny to run the servers for some software checks. We did notice that the frequency and voltage were poorly regulated until the load was increased. After we plugged in a 2kW heater the genny was able to properly regulate.

Thought / brain-fart: maybe when your house load is small the inverter can't regulate nicely? Try increase your load a lot and see if the problem is alleviated. Maybe also the new firmware will improve the controllers' performances

A bit of a 1000m view of voltage regulation (based on XP in 50-100MW solar and 500+MW coal generation (I'm left Eskom 10+ years ago - don't shoot me)). So Voltage is a function of reactive power, which in turn is a function of the phase difference between the current and the voltage sine waves. which is then a function of the firing angle of the thyristor stack. It seems to me that the voltage regulator is not able to find the right firing angle at low loads and keeps over-compensating. Because part of this game is played in polar co-ordinates (not the normal x-y axes) it means that some of the functions have some trigonometry involved (hope you paid attention in high school :D). If the non-linear behaviour is not properly taken in account the controllers can be badly behaved at operating points other than those for which they were optimised (high load vs low load). Thence my brain-fart: increase load or fix the controller

Note that grid tied inverters don't suffer these because if they did they would need to move the municipal voltage. Imagine you 6kW machine trying to control the voltage for your whole street... suburb... town... city...

The other interesting thing is that this seems to happen only on PV, but not on battery. Another idea may be that the same microcontroller is running the MPPT and AC regulation functions. When both are needed, then there is simply not enough processing power to do both jobs.

Finally I want to re-iterate that I am not an expert on inverters and how they work so the above is just spit-balling.

I am happy to be corrected

Edited June 23, 20224 yr by sahil

On 2022/06/20 at 11:57 AM, Guitaret said:

I have noticed that this only happens when the solar inverter(Axpert) is taking load from PV input, but not when it is on battery mode at night.

That makes me remind a problem I had with my Axpert MKS 5K: The MPPT when active produces lots of RI (radio interference). I noticed this as radio amateur and operating a AIS receiver station. Could it be that strong RI interferes with the control microprocessor?

Maybe ask the manufacturer what is the MPPT's response time to changes in load. If it's in the region of a few seconds, the inverter might not be able to supply the increased power demand fast enough as your UPS charger kicks in. Other devices might not be a problem to keep running until the new power point is reached, but a UPS could be a lot more sensitive to changes in supply voltage (which I guess is what you want).

Hi,

I have same model, same problem when working only from PV.

After changing some email with MPP Solar, they suggested the following:

"likely PV interference as we also have some other customers with this issue and may be relating to PV wiring run.  exact cause though is unknown at this time since we cannot reproduce this in our lab.   Try installing >15uf /500v capacitor wires if you can on the PV terminals and this is a known fix.  attached SOP for your reference."

 

I also have some newer firmware versions, that fix some bugs related to unstable output power.

 

Still there are lots of other open issues:

 MPPT issues on cloudy days

Low MPPT performance compared to other inverters (Voc 500Vdc)

 

Unacceptable charging battery from grid in case of Solar Only charging setting

The moment there is some voltage in PV, PIP6048MT is starting to charge battery with 4A from grid, although I configured to charge only from Solar.

 

AC Charging setting incorrect behavior

It seems that in case of UTILITY AND SOLAR charging setting, AC charging behavior is wrong:

2A MAX AC setting – DC clamp measurement is 15A, watchpower PC software was reporting 13A

10A MAX AC setting - DC clamp measurement is 15A, watchpower PC software was reporting 13A

20A MAX AC setting – DC clamp measurement is 25A, watchpower PC software was reporting 23A

 

Output source priority “Solar Utility Batt - SUB” incorrect behavior

In case of battery full (floating stage), PV was showing around 280Vdc, PV input power = 0W.

This means that Output active power was taken from grid, although it was on second priority.  

 

 

adding wire capacitor SOP.pdf VM III TWIN 6048MT main 60.90.rar VM III TWIN 6048MT main 56.97.7z

Edited December 6, 20223 yr by roadrunner79

8 hours ago, roadrunner79 said:

MPPT issues on cloudy days

Low MPPT performance compared to other inverters (Voc 500Vdc)

By my reading, these firmwares would be even worse than the 8 kW models, since they clamp the minimum PV voltage at 60 V (cf 90 V for the 8 kW, and 120 V for most 5 kW firmwares). But it would be good to see graphs to be sure.

Edited December 7, 20223 yr by Coulomb

Yes, you are right. Under low irradiance, PV voltage gets around 60V, inverter is not able to drawn any power out of 5.46kWp array.

There are 2 string x 6 pannels, Voc=300Vdc.

 

Regarding those firmware images, i believe that 56.97 is for VM III, while 60.90 is for VM IV model.

I have tested both on my VM III model, almost same behavior.

6 hours ago, roadrunner79 said:

Regarding those firmware images, i believe that 56.97 is for VM III, while 60.90 is for VM IV model.

That's what I would have thought from the file and folder names, but they seem to be much the same, with actually 60.90 being a little older. Both support 1.5 kW, 4.0 kW, and 6.0 kW inverters (24, 24, and 48 V respectively).

You think is possible to change min PV voltage in 56.97 firmware?

Yes. But I think it's best to wait until the dust settles on the PV fixes. 

Does anyone have some updates regarding 6048MT firmware?

Maybe a newer version? Or at least some fixes?

3 hours ago, roadrunner79 said:

Maybe a newer version?

I'm not aware of anything since 56.97, which has a date of 20/Oct/2022. 

On 2022/12/06 at 10:54 PM, roadrunner79 said:

Hi,

I have same model, same problem when working only from PV.

After changing some email with MPP Solar, they suggested the following:

"likely PV interference as we also have some other customers with this issue and may be relating to PV wiring run.  exact cause though is unknown at this time since we cannot reproduce this in our lab.   Try installing >15uf /500v capacitor wires if you can on the PV terminals and this is a known fix.  attached SOP for your reference."

 

I also have some newer firmware versions, that fix some bugs related to unstable output power.

 

Still there are lots of other open issues:

 MPPT issues on cloudy days

Low MPPT performance compared to other inverters (Voc 500Vdc)

 

Unacceptable charging battery from grid in case of Solar Only charging setting

The moment there is some voltage in PV, PIP6048MT is starting to charge battery with 4A from grid, although I configured to charge only from Solar.

 

AC Charging setting incorrect behavior

It seems that in case of UTILITY AND SOLAR charging setting, AC charging behavior is wrong:

2A MAX AC setting – DC clamp measurement is 15A, watchpower PC software was reporting 13A

10A MAX AC setting - DC clamp measurement is 15A, watchpower PC software was reporting 13A

20A MAX AC setting – DC clamp measurement is 25A, watchpower PC software was reporting 23A

 

Output source priority “Solar Utility Batt - SUB” incorrect behavior

In case of battery full (floating stage), PV was showing around 280Vdc, PV input power = 0W.

This means that Output active power was taken from grid, although it was on second priority.  

 

 

adding wire capacitor SOP.pdf 480.6 kB · 7 downloads VM III TWIN 6048MT main 60.90.rar 1.19 MB · 9 downloads VM III TWIN 6048MT main 56.97.7z 1.11 MB · 8 downloads

Can you please give me the CAP ratings if you know, I tried looking up it's reference # in the bulletin and didn't pull up anything? You mentioned >15mF/500v, is this a DC specific CAP? starting vs Run? when you mentiom >15 ...does this relate to # of panels in terms of Watts or voltage?

Edited February 6, 20233 yr by mafiose13