I have a shed that I keep my birds in and it has two windows with no other ventilation. The temp went up to 90 degrees even in this Spring weather. I do not have power to my building and it would cost 700.00 dollars to run power. So I went to Home Depot and purchased a 10 watt GAF solar gable fan and installed it. Actually, just set it up temporarily until I can mount the fan. Anyway, as soon as that little panel is exposed to sun, it starts the fan which cools down the building very fast. I am so impressed with how well it works. I really thought something like this would be a toy, but the fan really is powerful and keeps the air moving. If you have a coop or building that really needs venting, be sure to check it out. Of course, if you need a gable vent for your house, you can't go wrong with this unit. I will probably install a couple on my home soon now that I know they actually work as advertised. When the sun goes down, the fan stops (unless you have a battery), but by then the temps have lowered enough to keep everyone fairly comfortable and the eggs from cooking until I can get home to gather them.