Does anyone on here repair faulty inverter boards - shorted fets on Sunny Island

[rogerdw]

Hi, I've done a search to see if there's any one familiar with repairing circuit boards on Sunny Island inverters, with no luck so far.

Are boards available as a spare part?

I've been asked to fix an S18.OH-11 which has a heap of shorted mosfets ... F2907ZS ... and wondered if it's a common problem or if it should just be retired.

Thanks for any help.

 

[sunsurfer]

Definitely more damage then just the MOSFETs

 

[Brett V]

That board is toast

 

[MikeInKingman]

Not affiliated with, but have used in the past with no complaints or issues:

Mark Snyder Electric | Home

We are an Electrical contractor, Loxone Smart Home automation specialist, and authorized Xantrex / Schneider Inverter Repair center located in Poway, CA - San Diego county

www.marksnyderelectric.com

Best of luck and stay safe.

 

[TomasGrey]

Hi, I've done a search to see if there's any one familiar with repairing circuit boards on Sunny Island inverters, with no luck so far.

Are boards available as a spare part?

I've been asked to fix an S18.OH-11 which has a heap of shorted mosfets ... F2907ZS ... and wondered if it's a common problem or if it should just be retired.

Thanks for any help.View attachment 210093

Doesn't look good!

 

[rogerdw]

Definitely more damage then just the MOSFETs

Yes, though how much more is the question. Two smd resistors, a diode and a cap ... and likely the gate driver chips x 4 ... IR2113S ... $7 each.

Not affiliated with, but have used in the past with no complaints or issues:

Mark Snyder Electric | Home

We are an Electrical contractor, Loxone Smart Home automation specialist, and authorized Xantrex / Schneider Inverter Repair center located in Poway, CA - San Diego county

www.marksnyderelectric.com

Best of luck and stay safe.

Thanks for the suggestion, I will follow it up ... plus my days of living dangerously are long over.


And my original questions ... does anyone on here fix these things ... and are boards available as spare parts? Thanks.

 

[seneysolar]

Start here, see what a new board costs.

 

[Hedges]

Warranty from SMA? I think these are a fairly new model.
Out of warranty repair by SMA?

PCB assembly shops - if you brought a kit of parts could probably do it. I'd assume $500 minimum from my experience. May or may not be successful.

Do you know what caused it? I expect these to protect themselves from most things. But not reverse-polarity battery and maybe not grid applied to AC output.

 

[sunsurfer]

Yes, though how much more is the question. Two smd resistors, a diode and a cap ... and likely the gate driver chips x 4 ... IR2113S ... $7 each.

Or something that is not showing physical damage. Its worth a try but you never know. Have your buddy plug it in and power it up.

 

[rogerdw]

Start here, see what a new board costs.

Thanks. I'm in Australia but I'm sure they can point me in the right direction.

Warranty from SMA? I think these are a fairly new model.

I'm pretty sure the guy told me it was installed in 2017 so I'm not sure how much warranty they give them.

Do SMA have a repair service? ... would be cool if they did. Or simply pay the money for a new board if they supply them. Would save me a job anyway.

As far as cause, no one seems to know (or own up) to anything, and the replacement has been working fine. Not sure how long since it failed, I'm starting to think it may have been sitting around for a while.

Or something that is not showing physical damage. Its worth a try but you never know.

Haha, yep. Welcome to my world. That's a daily challenge.

 

[seneysolar]

Thanks. I'm in Australia but I'm sure they can point me in the right direction.

Sorry, try this one.

 

[Brett V]

Yes, though how much more is the question. Two smd resistors, a diode and a cap ... and likely the gate driver chips x 4 ... IR2113S ... $7 each.

What about the thermal damage to the boards? Somebody might kluge it but it wouldn’t be reliable.

 

[JayArr]

I repair inverters for a living and I would say that's repairable but the key is whether the signals are OK.

When we repair this kind of board we remove all of the FETs and then check all of the gates for proper signal. Use a Scope and make sure there is no DC component. If it's all OK then map out the array and you'll find they are in parallel sets. We put one FET into each set and test it with a small load. As an example a Xantrex Prosine 3.0KW unit will run with four FETs instead of 16. (four sets/quadrants)

If it runs with a minimum of FETs installed we populate the remaining locations and test again.

If there is no, or wrong, signals to the gates with all FETs removed you have to go deeper and repair the driver circuits.

Now with all that said - I don't know Sunny Island, I'm just into Xantrex and I'm way too busy to branch out into other makes or models so I'm not offereing to do this. I'm just saying that this looks repairable.

 

[rogerdw]

I repair inverters for a living and I would say that's repairable but the key is whether the signals are OK.

Thanks JayArr, this is the sort of response I was hoping for.

I repair circuit boards for a living too, just not necessarily inverters.

When we repair this kind of board we remove all of the FETs and then check all of the gates for proper signal. Use a Scope and make sure there is no DC component. If it's all OK then map out the array and you'll find they are in parallel sets. We put one FET into each set and test it with a small load. As an example a Xantrex Prosine 3.0KW unit will run with four FETs instead of 16. (four sets/quadrants)

That is extremely helpful, thank you.

I know a lot of the guys building ozinverters etc do that as well. And even to the point of removing the input capacitors, though that would be a lot of work on these boards.

I love your systematic approach, it's a good reminder for me ... and I appreciate that you're busy enough to not need to branch out. I normally refuse anything other than what I normally do ... but sometimes I get talked into looking at new stuff. And I'm open to looking at things that are expensive to replace because people will generally accept a higher price for repair if it is required.

If anyone ever turns up with a Xantrex I'll know where to turn. Thanks again.

 

[Hedges]

I'm pretty sure the guy told me it was installed in 2017 so I'm not sure how much warranty they give them.

Warranty 5 years, 10 years with registration.
Maybe they'll honor it to 10 years from date of manufacture, not knowing when installed.

https://files.sma.de/downloads/SI44M-80H-13-DS-en-31.pdf

Do SMA have a repair service? ... would be cool if they did. Or simply pay the money for a new board if they supply them. Would save me a job anyway.

I would think so. But try signing up on their Australia website and requesting warranty service.
Or contact any SMA installer in your area and ask them to do it for you. SMA pays some fee to installers for warranty work.

But since they sometimes just send a replacement inverter, maybe they invalidate warranty on the old one. If it was already dead when you acquired it.

 

[mciholas]

MOSFETs are usually not the CAUSE of failure, just the victims of it. You can replace them all, and the drivers, and the root issue might remain to bite you again.

For example, MOSFET gate drives often have zener diode protection and if that zener is faulty, everything may seem to work fine until some transient happens and the gate blows. That usually causes a drain to source short, blows some other MOSFET on the opposite side, and takes out the driver. You fix the MOSFETs, the driver, and everything seems to work, but that faulty zener is still there waiting to not do its job again.

One idea is to buy a working used version of what you have, put it into service, and now you have some spare parts from your first one if you need them.

Mike C.

 

[rogerdw]

Or contact any SMA installer in your area and ask them to do it for you. SMA pays some fee to installers for warranty work.

But since they sometimes just send a replacement inverter, maybe they invalidate warranty on the old one. If it was already dead when you acquired it.

Thanks Hedges. It's starting to look like this was replaced under warranty ... and has sat around since, for quite some time. And the guy who brought it in may or may not be the local SMA installer.

For example, MOSFET gate drives often have zener diode protection and if that zener is faulty, everything may seem to work fine until some transient happens and the gate blows. That usually causes a drain to source short, blows some other MOSFET on the opposite side, and takes out the driver. You fix the MOSFETs, the driver, and everything seems to work, but that faulty zener is still there waiting to not do its job again.

After fifty years repairing circuit boards, I love it when I finally figure out all the reasons that a particular board fails ... then I can confidently replace all the bits that 'usually' cause failures on them and be comfortable that there's a fair chance it will live a long life and I won't have to do it again for free.

Of course when you see something for the first time it's a different matter and then skills, knowledge (or lack thereof) come into play ... and it can pay to do some preliminary searches online or ask other techs ... hence this thread.

One idea is to buy a working used version of what you have, put it into service, and now you have some spare parts from your first one if you need them.

Yes I suppose that is an idea, though not very workable in my business model. Besides it is common for boards to have the same part fail or cause failures ... so using parts from a used board is fraught with danger.

I make a good living fixing boards and love the self employed lifestyle ... and the proof that the work is sound is the continuous supply of more boards from the same companies. And they love it because instead of paying perhaps $1k-3k for a new board they can have them refurbished for say 10-25% of new price. ... so my point is that while there are lots of things that could go wrong, it is not unreasonable to expect to be able to fix most boards with a decent attempt. And like one of my old employees used to say all the time, "made by man ... can be fixed by man".

 

[Hedges]

I just acquired a US Sunny Boy -41 series which did nothing with PV applied.
Opened it up and found liquid splattered and burst caps.

It has 3 PV inputs A, B, C. A and B read near zero ohms, C shows as correct capacitance.
I've pulled the PCB, plan to wash it with IPA, then try operating with input C powered.
Don't know if electronics survived however much over-voltage was applied, but if it does I'll replace caps on the other inputs.

 

[AntronX]

Is that a 48V inverter? Those IRF2907Z are 75V MOSFETs. Interesting that 1st tier brand would leave so little voltage headroom.

 

[Hedges]

600V caps (550V @ 105C) for 600V Sunny Boy.
Of course should only see max 600V cold, like 0C or below.

Transistors of course have a different set of issues.
Don't know if like an op-amp, where breakdown voltage varied with temperature.