Growatt inverters causes SCP fault?

[the_uglydog]

Hi, I have 2 Growatt SPF 12000t DVM inverters. The first I've had for a number of years and a few years ago it shut down with a burned main board and caused the batteries to all shut down as well. It was easy to see since there were burn marks so I replaced the board and it worked great till a few months ago it shut down again with only about 3kw load and the batteries this time stayed on and showed a Short Circuit Protection fault. I bought a replacement inverter which I installed a few months ago. I set the old one aside since I didn't have time to work on it. A few weeks ago the system shut down again also with only about a 3kw load once again the batteries stayed on and showed a short circuit protection fault. I can't find anything obvious wrong with either of the inverters. I have both covers off and inspected everything. Every time I try to restart the new one it trips the SCP fault in the batteries. The automatic capacitor charger seems to be working since after trying to start the system, I shut off the main breaker and for a short time there shows residual voltage at the inverter side. The batteries work fine when not connected to the inverter. I replaced the breakers to the batteries in case there was a short in one of them. Has anyone else had a similar issue, suggestions what we should test, etc.? I've been working with Growatt their thought is the same as mine, the main board but I inspected everything with a magnifying glass and can't find any evidence of heat damage anywhere.

 

[WorldwideDave]

Can you run your system on just one inverter and see?
Can you run your system on just one battery and see?
The only reason I have heard of is when someone connects the batteries to the inverters that large spark/tiny surge that happens can short things out on the inside. You sure your wires aren't touching somewhere they should not be? Post pix.

 

[the_uglydog]

I don't have both inverters connected. Today I'm going to try a smaller old inverter that we don't use anymore and see if that causes the same issue, just to be sure. I set my system up with a 250amp main breaker and a 200 amp fuse from the battery bank to the inverter. Each battery has a 100 amp breaker and a 100amp fuse from the battery to the busbar. None of the fuses are blown neither are the breakers tripped When the old inverter failed I decided to replace it with a new one and then repair the old one so I'd have a spare. I can't find any damage in either. Normally what I do when starting the system is, I make sure all the batteries and the inverter are shut off and all breakers off, no load, no solar and no ac connection. Then I turn on the main breaker between the batteries and the inverter, then the breaker between the battery I'm going to use to charge the capacitor, then I turn on the battery. After I hear the click of the pre-charge I wait till the green lights all come on then I turn on the inverter as per the battery instructions. When I do that now I can hear the little click of the pre-charger then the battery comes on then goes straight to SCP fault and stays there till I shut off the either the main or battery breaker. I don't get to turn on the inverter since the battery is in fault. After trying to start, it does seem to charge the capacitor since voltage shows on the inverter side of the breaker when it's shut off. Both of these inverters shut off while in use the only difference is the old one caused all the batteries to shut down and the new one only caused them to go into fault. Non of the breakers or fuses were tripped either time. I've also changed out the breakers, just in case one failed, it's the same. I've been working with Growatt the only thing they can think of is a short in the main board, every other time something like this has happened and I serviced one of them, it's a short in the main board. There's no burn marks anywhere. I'll try to upload the videos from my phone if not I'll redo them and upload them here. Thanks......

 

[the_uglydog]

I connected the inverter from the storage and it powers up just fine. So the problem has to be in the 2 Growatt inverters. Still working on pictures or videos.

 

[WorldwideDave]

So if you use your smaller older inverter and the same batteries and follow the same startup procedure, it works fine correct?

 

[the_uglydog]

Yes, startup went just fine doing that. After I told Growatt about doing this they are sending a new main board. They said to try it even though we can't find anything obvious wrong with the old board. I've been having a lot of problems with boards here. They thought that maybe since we are in The Philippines that the heat and humidity causes it, but, the power rooms are airconditioned and we maintain about 70* F and 40% humidity so that can't be the problem. Also it's not overloading since we never load them over 75% capacity and it's usually stays around 30% maximum load.