WVC 1200 Grid Tie Inverter Dc Input Short Circuited (Why?)

[Kedar264]

Hello Everyone

I have WVC 1200 grid tie inverter , one day i suddenly seen this fault where its dc input is shot circuited but luckily all 300 watt solar panels survived which is pretty interesting itself  here is my short video on it
https://youtu.be/7V0OxaaXbA4

i am new into this thing anybody have answer why the mosfets on dc inputs are blown in such way as shown in the video,below are part numbers of this inverter also these images might help.

# Wvc 1200 Parts

# PIC16F877A (MicroController)
http://akizukidenshi.com/download/PIC16F877A.pdf

# IRF3710 (Power Mosfet)
 http://www.irf.com/product-info/datasheets/data/irf3710.pdf

# CQ1308 / U2060G /MURF2060CT (Ultrafast Rectifier)
http://store.alhekma4u.com/content/Diodes/U1660G.pdf

# 30NM60ND (Power Mosfet)
http://tec.icbuy.com/upload/st/stw30nm60nd.pdf

# WVC 1200 Manuel
http://www.ostrovni-elektrarny.cz/docs/WVC1200-eng.pdf

[TheMG]

luckily all 300 watt solar panels survived which is pretty interesting itself

Short-circuiting solar panels is actually extremely unlikely to damage them. Photovoltaic cells behave much like a constant-current source, thus the current when short-circuited wouldn't be much higher than under normal load.

i am new into this thing anybody have answer why the mosfets on dc inputs are blown in such way as shown in the video,below are part numbers of this inverter also these images might help.

Without carefully analyzing and testing the circuit design and other factors it's impossible to tell. Could be anything from a manufacturing defect in one of the transistors to a poor circuit design, transients, overheating, driver circuit failure, etc.

With switchmode power circuits like this, when one part fails it very often leads to a cascade failure of many other components in the circuit.

[PIFOUBMW]

Thank you for this topic and for your Youtube video which helped me to identify the failure of my WVC-600 inverter 

Because overheating, my WVC-600 died 4 days after installation at full sunlight with same symptoms as your WVC-1200 but I have another one correctly working since 3 weeks.

After opening and removing solder, I was surprised to see than the IRF3710 component MOSFET N Trench 100V 57A 4V @ 250uA 23 mΩ @ 28A,10V TO-220 has been replaced in my recent module (bought 2019/08 but built in 2018) by the KIA Semicon Tech KIA3510AP MOSFET N Trench 100V 75A(Tc) 4V @ 250uA 11 mΩ @ 50A,10V TO-220 which seems to be more resistant (even if it burned in my case  ) Because low price, I just ordered 12 items on this website https://lcsc.com/product-detail/MOSFET_KIA-Semicon-Tech-KIA3510AP_C176880.html and I have to wait for delivery ...

I hope replacing the 4 mosfet will be enough to repair my WVC600 

[h90]

I have exactly the same device and the same problem...just ordered the KIA chips....
Please let me know how it works for you.

I unpluged mine from the electric under load....it didn't like it which is stupid because we often have power failure.

[PIFOUBMW]

Yesterday I received the mosfet and replaced them and now my wvc600 is fully working again 👍

[h90]

great news....now I only need to find mosfets...

[PIFOUBMW]

To temporary repair your WVC, you can buy  IRF3710 which is the first mosfet used, and when you will find the KIA just wait for your WVC be defective again and replace with KIA next time

[katzi74]

Hi everybody, I'm picking up the WVC-300 repair topic with a question I currently can't answer myself. In the thread it is about a short on the DC input side. My problem with the Inverter is, that there is a short on the 230VAC side and I identyfied one of the mosfets (see attached Image, mosfets indicated with blue circle) to be faulty. I removed it and there is no short anymore, so there is a good Chance to fix it with a new mosfet. Ok, here is my question, does anybody know the type of mosfet that is used on this inverter. Unfortunately it does not have a type indicated on the housing. I'd very much appreciate any help. Thanks! Robert

[PIFOUBMW]

Can't see your picture 

[katzi74]

Hi, sorry, I was sick a few days but still I'm interested in fixing the WVC-300.

See attached image of a WVC-1200 with the relevant mosfets indicated with blue circles. This is the mosfets that are also used in the WVC-300, of course it is only 4pcs. there.

Does anybody have a clue what type it is?

Thx, Robert

[syntax1269]

Was hunting around a replacement for the KIA Semicon Tech KIA3510AP in case they stop making them, or stock becomes unavailable for some reason as well as to give the inverter a bit of a boost to handle even more power.
I have found a good replacement from ON Semiconductor Part Number   HUF75645P3 , Description   MOSFET N-CH 100V 75A TO-220AB
the spec sheet is almost identical to the KIA replacement with a bit more tolerances to heat. 

Just posting this up here in case someone finds this post and looking to replace the mosfets with something else. If you do, let us know how it worked out! Maybe we can get this to pump out 1500watts or more is we just upgrade the mosfets to handle more power.

[pauloscheidegger]

Hello guys,
I had about the same problem with my WVC600 micro inverter some days after putting it under the sun, but when I opened it to look for the 4 culprits I found 8 of them. 4 FETs for each panel. All shorted. They where so cooked I could not even read what one day they were.
I got a message telling me this topic is rather inactive, but since my inverter was bought about the same time ago, it was kind of a surprise to find those small FETs instead of the TO-220 package. They are about half the size of TO-220 or D2PAK, even smaller than a DPAK too. I don't know that package, but have found some of them in electric model airplane speed controllers too. They look like SOIC-8 IC.
Do any of you know them? I'd like to use a standard TO-220 package FET instead, since those smaller guys may be difficult to find here, but I should at least know the pinout and original specs to check how to select the substitute. Of course, they are used in parallel pairs and I'll have to consider it to replace them.
Please find attached picture.
Thanks in advance for any help.