Yes, you are right, I have found that Sunrous Inverters are not reliable 3 out of 5 have failed and any help from their company in China is poor and slow, the output FETS die ‘ they were kind to replace one with their new 5kw model with much better cooling, but it died too, because a nut from production was screwed down under the PCB and shorted the output board ‘ these guys have cost me a lot of $$$$ I have Changed to SMA Sunyboy and had no’ problems.