I bought these solar powered fan kits for a 10' x 20' greenhouse and installed them in west wall of the greenhouse. With sunlight on them, they just buzz away, pulling hot air out. I just ordered another set of fans for the other end.
Mine are installed on the inside of a polycarbonate panel and that worked great. I like the enviro-friendly packaging, but could use a little something between the panels as mine had a very minor scratch on each panel where they rubbed together during shipping.