TL/DR: author had a bad connection in their solar system. Despite having burning smell of electronics, seeing blackened wires, and having parts so hot it burned their fingers, they did nothing and kept the system active until things got so bad the inverter shut down with fault code. They got pretty lucky nothing caught on fire or melted.
Their problem was that one of the screws got loose, and their suggested fix was to re-tighten them 6 month after installation. This is a good idea. I'd also suggest using wire ferrules and not ignoring blackened wires and smells from high-current electronics.
The failure here wasn't overcurrent, which is what fuses (or breakers) mitigate. Here it was poor connection, no fuse or breaker would help. And in fact didn't since the author mentioned he had breakers on these lines.
Also, and particularly in high current circuits like these, fuses generate significant heat on their own, at the connection points.
The better bet is to look to conservative standards (like ABYC for the marine industry) and follow their rules for wire termination. In this case that would be properly crimped ring terminals over simply wrapping stranded cable around a screw. That said I am sure the NEC has something to say about domestic solar installations.
The idea is your inline fuse overheats and melts instead of the entire controller turning into fire due to the heat cooking the plastic at the rail or terminal. It's a passive device for both overcurrent and overheating. Or just step into 2026 and use mag breakers, there are lots of DC breakers that do this: https://www.amazon.com/Miniature-Circuit-Isolator-Magnetic-D...
TL/DR: author had a bad connection in their solar system. Despite having burning smell of electronics, seeing blackened wires, and having parts so hot it burned their fingers, they did nothing and kept the system active until things got so bad the inverter shut down with fault code. They got pretty lucky nothing caught on fire or melted.
Their problem was that one of the screws got loose, and their suggested fix was to re-tighten them 6 month after installation. This is a good idea. I'd also suggest using wire ferrules and not ignoring blackened wires and smells from high-current electronics.
Inline fuses and breakers are a thing. Use them. Or don't. There's no electrical code in the middle of nowhere.
The failure here wasn't overcurrent, which is what fuses (or breakers) mitigate. Here it was poor connection, no fuse or breaker would help. And in fact didn't since the author mentioned he had breakers on these lines.
Also, and particularly in high current circuits like these, fuses generate significant heat on their own, at the connection points.
The better bet is to look to conservative standards (like ABYC for the marine industry) and follow their rules for wire termination. In this case that would be properly crimped ring terminals over simply wrapping stranded cable around a screw. That said I am sure the NEC has something to say about domestic solar installations.
The idea is your inline fuse overheats and melts instead of the entire controller turning into fire due to the heat cooking the plastic at the rail or terminal. It's a passive device for both overcurrent and overheating. Or just step into 2026 and use mag breakers, there are lots of DC breakers that do this: https://www.amazon.com/Miniature-Circuit-Isolator-Magnetic-D...
Do you smell chicken?