I'm converting a shed to a "sun-shed" with the south gambrel roof glazed and the north wall and roof insulated.

In an effort to pinch pennies, I found a seller of some used polycarbonate panels on craigslist. The ad is silent about how old the panels are.

Is there any way to determine which is the proper (UV shielded) side to install outwards?

Is this a bad idea? Is there any way for me to determine the remaining life of these panels?

Should I just suck it up and pay the additional $200 to get new materials?

Thanks for any advice!