Clear vinyl, polycarbonate and acrylic windows requires special cleaners and waxes to preserve the plasticizers that keep these marine enclosure materials from drying out, yellowing and cracking.
I have used a number of these special formulas and found one that I really like – Meguiar's Clear Plastic and Vinyl Window Wax. It is easy to apply. Make sure the panels or curtains are clean first, then mist it on with the spray bottle and wipe it off with a microfiber towel. It leaves my polycarbonate enclosure clear and streak free, and its synthetic waxes also provide UV protection.
The wax also has a very pleasant smell that reminds me of tropical fruit punch. A 16-ounce spray bottle sells for $16.99 at the Meguiar's Direct website.