Axpert VM 3.2 burning again and again within a week

[irfangul]

I am using Axpert VM 3.2 under brand name Inverex in Pakistan, it worked without any issue for the first year, I have four 330 watt Trina Tall solar panels connected pair of panels in series then these 2 pairs connected in parallel with inverter so it match the inverter specs.

I had no issue for one year but one day I found out that 0 watts are coming out of solar so I reported the issue to the local company from where I bought it, they said inverter has some issue in its Solar Controller and repaired it. Then after 1 week of repair I felt burning smell coming out of inverter, the inverter was gone. I again took it to local company this time they replaced the whole board with new one but what a bad luck it blew again after 1 week, they repaired it again, and It blew again within a week. Long story short, now I am hopeless with this product and unable to understand what is wrong with my system, I had the whole systems inspected by a site engineer of the company but he couldn't find anything wrong with the setup.

The latest images of burned inverter are attached, I can see burned MOSFET my idea is its Solar Charge Controller again. See if someone can help me here, i can give more details about the system, I am a software developer by profession so please consider me a noob here. Thanks

Edited November 7, 2019 by irfangul

[irfangul]

Have a look at this also.

[Coulomb]

1 hour ago, irfangul said:

this time they replaced the whole board with new one

I wonder if they really did.

It sounds like the battery-side capacitors have dried out in the Pakistani heat (guessing you're in Pakistan, that seems to be the only country where Inverex branded inverters are sold). These capacitors (there are 4 of them in a 5 kVA model) prevent spikes on the battery-side from blowing the MOSFETs. It looks like some of the driver transistors were also affected. It can be quite a job finding all the blown parts and replacing them all; if you miss just one, it can blow again. But that's usually immediately. With the one week delay, that sounds like the capacitors are weak, and are absorbing many of the spikes, but one in a billion (?) cycles they're not good enough, and the MOSFETs blow.

Personally, on all my inverters, before I use them I replace these capacitors, which are rated at 2000 hr @ 105°C, with slightly more expensive types rated at 10 000 hr @ 105°C, and the MOSFETs with higher voltage types. It all comes to about AU$100 (US$70). Doing this early means you don't have to find all the blown gate driver components. I've had no problems, but the climate here in Brisbane, Australia is probably milder than the climate in Pakistan. Though we happen to have 39°C forecast for tomorrow, and the start of summer is still weeks away.

[irfangul]

@Coulomb I have checked the board myself it doesn't look like a year old board but more a month old. I am using 3kVA VM axpert model see specs in the link user manual of 3.2 kVA

My personal guess is it has something to do with the solar charge controller, I am not sure about it. your are the expert here. looking for your guidance.

I can give you more pics, may be a video of the board if you want.

Edited November 7, 2019 by irfangul
missed something

[Coulomb]

26 minutes ago, irfangul said:

My personal guess is it has something to do with the solar charge controller

Well, the Solar Charge Controller might be pushing the battery voltage too high.

Is it possible that your battery has a high internal resistance?

Or are you running it without a battery?

[irfangul]

Yes, its connected to batteries, the Inverter doesn't start without batteries, How can I make sure its the same issue you are talking about? I am using tubular flooded batteries connected in series to make 24 volt.

Edited November 7, 2019 by irfangul

[Coulomb]

1 minute ago, irfangul said:

How can I make sure its the same issue you are talking about?

I believe that you can still charge the battery even if the inverter proper is broken and the inverter is displaying a fault code. Watch the battery voltage when it charges the battery. You may have to put a load on the battery (e.g. several car headlights in series, at least 6 of them) to "make room" for a proper charge.

The battery voltage should not rise much beyond the settings (often 56.4 V, setting 26). If it gets to say 58 V, then that could be the cause of the problem. It may be that you need to service the battery (e.g. water it if it's a flooded type), or replace it. It's not uncommon for lead acid batteries to be discharged too deeply, causing them to age prematurely, and one of the symptoms is much-increased internal resistance. So it will sag more under load (but without the inverter working you won't see that), but also the voltage will rise too quickly when charged.

[irfangul]

Just to give you more details, I am using 2 , 12v batteries connected in series, Assuming you are talking about overcharge protection that is 32 volt in my case with 24V system. Right now batteries are connected with another 24V modified sinewave inverter without solar capability, which I am using as a backup for lighting up my home. its working fine without any issue.

Edited November 7, 2019 by irfangul

[Coulomb]

8 hours ago, irfangul said:

Just to give you more details, I am using 2 , 12v batteries connected in series, Assuming you are talking about overcharge protection that is 32 volt in my case with 24V system. Right now batteries are connected with another 24V modified sinewave inverter without solar capability, which I am using as a backup for lighting up my home. its working fine without any issue.

Ah. I'm far more familiar with the nominally 48 V models. So just halve those numbers: setting 26 is probably about 28.2 V, and if they go above about 29 V, then the inverter might be in trouble.

Are the voltages of the two nominally 12 V modules about the same?

What sort of batteries, what capacity?

[irfangul]

Quote

setting 26 is probably about 28.2 V, and if they go above about 29 V, then the inverter might be in trouble.

On my Inverter setting 05 (Battery type) is set to FLd (flooded) which means bulk charge is 29.2V , I will check any abnormality in it.

Quote

Are the voltages of the two nominally 12 V modules about the same?

Will check this out and get back to you.

Quote

What sort of batteries, what capacity?

I am using Osaka Tubular 180Ah 12V Batteries 2 modules, check this out Battery link 

For this battery charging cut off when fully charged is around 14.4V to 14.6V . with two in series its exactly around 29.2 .

Edited November 8, 2019 by irfangul

[rastert111]

this inverter has max Voc of 102V , by anychance you have more than 2 connecting in series making total Voc above 102v?

On 2019/11/07 at 4:05 PM, irfangul said:

I am using Axpert VM 3.2 under brand name Inverex in Pakistan, it worked without any issue for the first year, I have four 330 watt Trina Tall solar panels connected pair of panels in series then these 2 pairs connected in parallel with inverter so it match the inverter specs.

I had no issue for one year but one day I found out that 0 watts are coming out of solar so I reported the issue to the local company from where I bought it, they said inverter has some issue in its Solar Controller and repaired it. Then after 1 week of repair I felt burning smell coming out of inverter, the inverter was gone. I again took it to local company this time they replaced the whole board with new one but what a bad luck it blew again after 1 week, they repaired it again, and It blew again within a week. Long story short, now I am hopeless with this product and unable to understand what is wrong with my system, I had the whole systems inspected by a site engineer of the company but he couldn't find anything wrong with the setup.

The latest images of burned inverter are attached, I can see burned MOSFET my idea is its Solar Charge Controller again. See if someone can help me here, i can give more details about the system, I am a software developer by profession so please consider me a noob here. Thanks

 

 

I have same inverter though only running two panels in parallel though I plan to change next year.

 this inverter has max Voc of 102 V , highlighted in bold text of your post ,with 4 panels the Voc is goign to be over 180V (assuming 45V Voc).

that may be your problem...It is winter now temps have dropped maybe that contributed? how you were able to run 4 in series, that is mind baffling.

this inverter takes max 2 panels in series (assuming 45+V Voc).max 3 in parallel. (6*325=1800 Watts).

try removing 2 panels in series. see if it solves problem....

 

[irfangul]

On 2019/11/12 at 12:31 PM, rastert111 said:

 this inverter has max Voc of 102 V , highlighted in bold text of your post ,with 4 panels the Voc is goign to be over 180V (assuming 45V Voc).

Voc will not go over 90V because All the 4 panels are not connected in parallel, I have made 2 pairs of series so Voc is 90V for each pair then these pairs are connected in parallel which has not effect on voltage, This system was operational without any issue for one year.

Any other idea ?