Rand Solar Powered Attic Fan-8 Watt-W Roof Top Ventilator NEW!! Always runs on free solar power. If the Sun is shining on the solar panel, the fan will be spinning. Drastically cuts your cooling bill. Pays for itself in a VERY short time, good for the environment. Ventilates up to 700 square feet of attic space with its 435 CFM capacity. For installations with larger space or higher heat load, you can install more fans or use one of our larger 30W or 40W rooftop fans. High Efficiency long life brushless motor starts up even in lower light and overcast conditions. If you are looking for a fan that will run at night, check out our 10W and 30W fans with battery backup. No wiring to perform. Unit is self-contained. Just mount it to the roof and it works automatically. If you are looking for a fan that will allow you to adust the solar panel angle, check out our larger 30W and 40W rooftop fans.