When looking for second-hand panels, you have to accept beforehand that they are likely to be damaged
. Some defects are easy to identify, others can be revealed only with the help of an expert or special equipment. For example, a broken junction box is self-evident, but microcracks can't always be found with the naked eye.
The damage to a PV module isn't always critical, but can be troublesome nonetheless: the output of a solar panel drops and, in some cases, the lifetime of a module decreases. Some problems you can fix yourself if you are up for it – for example, replacing a broken bypass diode is rather simple. However, sometimes it is not just worth it. Moreover, if you've bought damaged panels from someone, getting warranty support for them is usually a pipe dream. So, while purchasing old PV modules might save you money, it's a risky move overall.