Solar Attic Fan 10 Watt Unit Attic venting is an important aspect in maintaining a healthy energy efficient home. Proper venting cools your roof extending the materials life and reduces the load on your air conditioning system. Attic venting also increases fresh air circulation. Powered completely by free solar energy, this sleek and efficient vent is both compact and quiet. Fully operational right from the box, it installs easily with no electrical wiring. And let's not forget powerful! Operating up to 850 cfm, a single 10 watt unit can fully vent up to 1200 square feet and a 20 watt unit vents up to 2000 square feet.