Suntuf Clear Polycarbonate Roofing Panel. I'm wondering how well they hold up for a greenhouse.
Clear, single layer, corrugated polycarbonate panels are available from several sources. Most are UV protected and work well for greenhouses in warmer regions without hail problems, and looking for spring to fall production.
The difference in sources is in the crating/shipping charges and the length of the warranty.
Here is a link that might be useful: polycarbonate panels
I used them as a roof to a greenhouse we built and its been 3 or 4 years and they still look great. They've taken some good hail too.