New testing conducted at France's oldest PV system have shown that its solar modules can still provide performance values in line with what the manufacturers promised.
There's a typo in the title. If you go back to the original source (in french), they actually retain 79,5 % of their original efficiency, so even better than the article's title would have you believe.
As far as I know that's nothing to write home about, monocrystaline solar panels get like ~30 years dropping down to 80% and then slowly begin to fail from there. I'm far from an expert, but my understanding is this is the norm and that if we found out they weren't lasting this long then people would be getting worried about a messed up cost calculous.
The weird thing is that in this scenario these panels are still applicable for replacement probably because the the solar panels of today compared to then are about ~40% more efficient. So compared to a new replacement it's at around 60% efficiency. A major site plans profit off of 30 years and plans to replace glass at that time, so while it may still be somewhat useful long term it's probably more profitable to replace them.
I doubt they put out much power at all compared to modern panels. Solar back then was a pipe dream, we didn't have the battery technology to store the energy and the panels had a lower voltage and could supply less current.
I have a 100w foldable panel for camping that at >= 20% efficiency is probably double what the 90s panels could do.
It’s good to know that they have pretty good longevity. One thing complicating this is that panel technology has gotten better and better during that time. There’s a graph on Wikipedia plotting how much better the various types of panel have gotten since the 70s. A lot of them have doubled in output since the early 90s.
So on the one hand, these old panels are outputting 75% of what they started with, which is good. But on then other hand they are only outputting about 37% of what new panels could.
Not that we should throw old panels away. There’s plenty of sun to go around (though I guess the average homeowner only has one roof to use). It’s just interesting how fast the tech has improved and how that might factor in to some longevity calculations.
Fortunately and unfortunately, there have been so many changes and breakthroughs on solar power over the last 50 years that this doesn't really tell us much about current technology.