Fun With High-Voltage Electronics

This weekend, one of the inverters in our solar array was showing a fault, and was off-line. Normally, this would have been a problem, because it would have meant calling the company that installed it. Now, they did a good job with the installation, and I have no problem with their technical expertise with these systems, but there were issues during the installation, and there is still one outstanding issue with them that they refuse to communicate with us on. So while they are obligated to support the system, and I would call them if there was something wrong, I’m going to explore other options first.

I checked the manual for meaning of the error code, which explained it and basically said “call the manufacturer (of the inverter)”. Not good so far. I went to their website, where I knew they had a forum, and was able to find a post with the same problem, and the tech had pointed that person to a technical document they had published, saying that it was possible to fix this problem in the field.

I downloaded the 4 page PDF, and started to read, immediately seeing the words “The Sunny Boy Inverters operate with potentially lethal voltage and current from multiple power sources. Only qualified personnel should attempt to work on the inverter”. It promised to be interesting…

It turned out to be a fairly simple proceedure, jumpering a couple of sets of pins on the main board, applying DC power, removing the jumpers in a certain order, and applying AC power, but it was done with the cover off and all sorts of warnings of lethal voltages visible. Really steady-hand-inspiring stuff.

Everything worked the first time, the inverter came back online, and all is well. I’m still not sure if I should be thinking “nice job”, or “what was I thinking?”, but I still have my healthy respect for potentially lethal voltages and currents, so I’m going with the former.

Some keywords which might help other owners: SMA SunnyBoy 2500U EEPROM_d error