zweifuss parent
Certainly not. But old solar cells that still have a certain lifespan can be obtained almost free of charge by anyone who wants them.
Labor of installation is anywhere from 5 to 25% of the cost, depending on location. Add in any missing parts (wiring, inverters) and permitting costs, and you may find yourself just as well off buying new panels for the added efficiency.
You'll either need less labor and materials, or get more output from the same land space, depending on your needs.
Reusing old cells makes sense in some applications, but for almost anything commercial or not a handyman special, I don't know that the numbers work out very well in their favor.