Should I buy a used system?

Used solar panels need to be pressure tested BEFORE driving lag screws into the roof shingles.

Buying a used system can be very risky. Usually, the system you are about to buy has already been removed from the roof (following house renovations hopefully), or worse, to ease the sale. How then will you know if it still works? You might want to pressure test the collectors, il you have the necessary tools for the job.

Most certainly, no solar expert will do it for you, because there is nothing for him to gain from helping you out with a used system. Furthermore, he won't give you any warranty that the panels will still work after YOU install them on your roof.

Otherwise, removing it will cause the damage. Only Heliocol and Enersol solar panels can reduce this risk, the first because of the ease of repairs, the later, because it's more fragile components are inexpensive.