We got back from our sailing trip and switched the solar battery bank inverter back on. We had turned it off because the batteries were a little low when we were leaving after a few cloudy days, and I wasn’t sure I could explain exactly how to monitor and switch the system to our house sitter.
The next morning, the inverter in the cellar was making the beeping sound that indicates a fault, usually a low battery. The inverter is the electronic gizmo that converts 12 volt DC from the solar panels and the batteries (like your car battery) to the 120 volts AC that house circuits are wired on. It was beeping. But the batteries were full.
When I rebooted the inverter, it made an arcing noise and blue electrical sparks were visible out of the ventilation holes in the back. Not good. The inverter is about four years old, and out of warranty, but it shouldn’t be failing so soon. I made a mental note to add troubleshooting the inverter to my weekend chore list, but I also started pricing replacement inverters online.
Still, based on what I remember from my electronic/ham radio/geek days of high school, I thought that arcing was an unusual way for electronic components to fail. Electronic components usually just burn up. Arcing requires high voltage bridging an air gap so narrow that the air turns into an electrical conductor — sort of like mini-lightning. So it might be worth opening the unit up (carefully!) to see if something got inside to bridge the air gap between high voltage components.
Sure enough, poking around with a stiff insulated wire where the arcing had occurred, I pulled out a crisp object. An actual bug. You can see the bug on top of the inverter case in the picture above. After removing the bug and smoothing out the burned edge of the circuit board, the arcing went away.
The inverter is back on and has been happily powering our (smallish) fridge since Saturday.