Solar Panel long-term performance
The ISS is a good test environment for solar panels in a worst-case environment.
* frequently heating/cooling every 2.5 hours [or whatever it is] as they orbit
* exclusive source of power for ISS and must be reliable
* "up there" for years, not so easy to replace or repair
So far they seem to be doing very well. Hopefully the replacement/upgrade panels will outperform and outlast these, as the tech develops.
(I would like to see a method of producing power via solar wind, especially for interplanetary craft)
Solar cell disposal, however, is another problem entirely. Recycling is best (due to things like CE prohibited materials, etc.) but can it be broken into panels and returned via Dragon capsules? That's where a Space Shuttle would be more effective.. (ok these are staying up there for now but eventually)
And while they're at it, they should send up some additional modules to go with the extended power availability... and maybe some (laser, TIG) welding equipment and laser or plasma cutters (if not already there). I'd like to see them get a head start on orbital construction on a much larger scale.
then they'll need MORE panels, MORE modules, and MORE trips to/from ISS. But when the ISS is all connected, you have one "thing" orbiting, i.e. easier to control the orbit.