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 lucking nothing caught on fire or melted.

They 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.