In our service rounds, we sometimes come across in-your-face results of either dodgy components or dodgy practices. The latter is intriguing, as even quite decent components can go faulty with potentially disastrous results, IF the original installation practice was lacking.
Here are two cases of 'burn-outs' of components.
A German brand of connector! Unfortunately, placed by the installer in the channel of the mounting rail. It would appear that water just happened to gather at that point, and allowed tracking, then arcing, over a period of time; to result in the charred mess in the photo. I always wonder what would've happened if lots of dry pine needles were blowing about under the panels (and into the frame) at the time this was happening.
This is an example of the more common Chinese brands of connectors widely used some years ago, and with the problem being there was no surety that different brands of the same 'model' connector would connect properly, in the range of different circumstances they would be subjected to, over the years. We still don't know if that is exactly the case here, as it is hard to tell due to the extreme erosion and charring of the connectors.
If so, the mismatch typically occurred between the array-cable from the inverter, and the panel(s) in the array it connected to.
Suffice to say, the connector pair was subject to a storm incident, and the connectors burnt out shortly after that. Perhaps the pair was dislodged and swung about in the wind sufficiently to loosen the touching points of contact? Followed by sitting in a bit of water on the roof? Who knows. We do know that a correctly matched brand and model would have had the best chance of not arcing out in that situation.
In both cases, it underlines the importance of quality best practice in preventing fire-damage to your solar!