Solaredge DC system.
Maybe it was just sloppy wiring, poor wire stripping, or not pushing in wire enough, or over/under torquing.
Thank you for the valuable thoughts.
I was just thinking about this, reading through. If you damaged the strands during initial stripping, and then over-torqued the block, I imagine you could sever strands pretty easily, leading to increased resistance, heat, etc. We've seen a number of these melt; polaris, burndy, panduit, doesn't matter. I have searched the internet for hours trying to find recalls, examples of bad batches, etc. I'm convinced it's installation error 100% of the time. Having a properly calibrated torque screwdriver/wrench is critical.
@electrofelon The Panduit PCSB4 has a torque spec of 50 in-lbs for #4-#8, and 45 in-lbs for #10-#14. I see this on a lot of panelboards we install as well. Different torques for the same size lug depending on wire size.