It’s complicated and the resources in this category dive into a lot more detail but in summary:
- faulty and non-compliant components need to be identified and removed
- used solar panels have already collected Renewable energy certificates so buying new (with new certificates) is very cheap.
- installers need to properly design a system which has used solar panels, so it is more work for them - easier to just provide a whole new system.
- some panels will no longer meet the standards
- some inverters will not meet the standards because there have been many improvements to make the systems smarter.
of course that doesn’t mean we shouldn’t create systems to make the most of working systems - it just means it is harder.