Growatt 3000TL PV Inverter lightning damage

[nygma]

Hi Everyone,

We had a big storm last week and my inverter stopped working. I have a raspberry pi hooked onto the RS232 port of the inverter which is still able to communicate with the inverter and can get the DC voltage out of the it but nothing else. You can see the log here if you are interested:
http://pvoutput.org/list.jsp?id=32841&sid=30101

It seems my insurance covers the replacement device so I will end up with this half bricked unit as a "backup". As far as I can tell the processor is still working, and it also senses the AC side because when I turn the AC breaker the fault light comes on. It also responds to knocking on the unit which turns on the LCD backlight, but nothing is shown on the screen. Other than that it does nothing. It does not generate the usual heat and I don't hear the humming noise that is the usual indication of the unit working.

I would be tempted to service to unit myself in case I get lucky, but I would only start it if I can get some help. I am not experienced electronic engineer I don't even have a scope, so it might be a difficult journey.

What would you suggest. Take it apart, take some picture post them here? Look for obvious burned out parts?

Thanks in advance,
Csongor

[ElektronikLabor]

That is a serious device; If I were you, I would be careful to repair such devices which manage kWs of power. 

Did you already tore down the inverter?
You could look for some obvious damages: burned transistors, strange smell etc.

Can you take pictures of the PCBs?

[nygma]

Thanks for the warning. I have not done anything so far. It is still up on the wall untouched. Actually I may deal with the replacement unit first before servicing it.

But I will be very careful and post picture of the PCBs.

[nygma]

The replacement unit has arrived yesterday and I swapped the units today. At least I am generating again.
I have done the first steps of removing the lid a taking some photos, but I did not have the nerve to dig any deeper.

It is not going to be easy. There is no visible damage, no strange smell, nothing. The unit was cleaner inside than my workbench. There is a rubber seal all around it, no dust gets in normally.

There was a fuse in the right bottom corner. I have taken that out check it with an ohm meter and it works, it is not blown.

I had issues uploading the pictures to an image sharing site (company laptop, browsing policy), so they ended up in Google+:
https://plus.google.com/photos/107708713303271671804/albums/6164414892063109873?authkey=CM7C8c-4yKTLTA

Have a look and tell me what you think.
After watching Dave's shows at least I can tell that the caps are high end (Nippon Chemi-con).

Cheers,
Csongor

[Richard Crowley]

Lack of visible (or smellable) clues makes it more difficult to trouble-shoot.  And lack of service information (like schematc diagram) makes it even more difficult.  And then, as if you needed any more difficulty, as medvedev said, high-power devices are more difficult to work on, even for well-equipped professionals.

[ElektronikLabor]

I'm curious about the microphone: why Do an inverter need one? 

I can't find any visible damage, however the construction looks very nice 

Can you power up that beast?
You could measure the voltages. I can't find any voltage test points; if there are no test points, you could measure the voltages across the (smaller) caps.
The are some voltages which are common:
On the digital Board: 1.8V, 3.3V, 5V
For analog stuff: +-5V, +-12V, +-24V
For example if you measure 3.1V on one cap, then it could be a problem there, which you can investigate.

Please keep in mind: It's very dangerous to dig around inside disassembled devices which are connected to the mains. 

[oldway]

Without connecting the inverter to the mains and beeing sure that all the electrolytics capacitors are fully discharged, I would first check all what is in direct connection to dc input and ac output as the power devices (mostly the mosfets) and the optocouplers with a component tester (such as an Huntron 2000 or Hameg scope) or with a multimeter.

Further diagnosis requires service manual, spare parts (and firmware if needed) and knowledge in power electronics.

[nickbenjones]

You would think that the manufacturer would build in some sort of overload protection on the mains side and the dc input side.

[Richard Crowley]

You would think that the manufacturer would build in some sort of overload protection on the mains side and the dc input side.

It probably isn't that surprising. When you get into equipment that big, the protection gets to be pretty big also, and it is expected that protection will be provided externally.

[NiHaoMike]

If nothing else, try selling it to knurlgnar24. He did a lot of inverter teardowns, repairs, and mods over the years and I'm sure he will like to try doing it with a solar inverter.

[poot36]

I would take the top board out as it looks to be digital only and take some more pictures of what is underneath it.  I would also go and test all of the opto isolators, any transformers, diodes and power semiconductors with your multimeter and check that they are not open or completely shorted.  See if you can find any fusible resistors as well.  If it is possible to take the back cover off it would be great to get a look at the tracks on the circuit board as well.