That moment my solar install started smoking during a heatwave in Phoenix

I was up on a roof in Phoenix last July, just finishing a small repair job, when I looked over at a neighbor's new solar panels and saw actual smoke coming from one of the junction boxes. My first thought was 'oh crap, that's not just dust burning off.' I called 911 immediately and warned the homeowner who came running out. The fire department got there in like 8 minutes and cut the power to the whole system. Turns out a wire nut had come loose inside the box, and with the 115 degree temps and full sun, it just cooked until it melted. I ended up helping the guy file an insurance claim, and now every time I'm on a roof near solar gear I check those connections with a thermal camera. Has anyone else seen those cheap MC4 connectors fail in extreme heat?

3 comments

3 Comments

knight.oscar1d ago

Friend of mine had an inverter catch fire same way, melted right through the disconnect.

evan_anderson1d ago

Switching to a fused disconnect fixed that problem on my setup.

harper_owens1d ago

Melted right through the disconnect... that's a scary one. But usually the disconnect is made to handle that kind of heat, at least for a bit. Like, a proper fuse or breaker is supposed to pop before things get that bad. Maybe it was a cheap disconnect or the wrong size for the circuit... could be the fuse didn't have time to clear because the short happened right on the inverter side. Still, glad your friend is okay, that stuff can turn into a real mess.