It’s tough to say, it depends on the failure modes.
Certainly one failure mode is just “wearing out” – Being exposed to light and heat for a long time just causes changes in the structure of the panel that prevents it from producing power anymore.
Another failure could be related to damage to the frames or wiring, another could be related to stuff like kids throwing rocks or fat birds landing on them or high winds.
The first one could be highly overestimated because they test MTBF by running in an oven basically, and so if their models of thermal acceleration of damage are off, it could be a problem.
The second on the other hand could be highly underestimated.
Yet another failure mode I just thought of is “no failure mode at all”. People will replace solar panels not because there’s anything wrong with them, but because there’s a newer shinier model out there. It happens, believe it or not!
Big reason for a secondary market to develop. Lots of people would happily install second hand solar panels with 40 years of life left.
I never thought it was bad. We have tonnes and tonnes of problematic garbage, but solar panels made from aluminion framing and silicon can just be put on a landfill if there’s nothing else to do with them. Just make a special landfill and that’s it, I bet it’s 1000 times better for the environment than putting normal household trash in a landfill.
everything about energy production