CDT-F1 Solar Power Fan - 1Watt solar panel & 3 inch Fan #34001 Easy to install in minutes, no need for 120V wiring or a city permit. Fits 3 inch opening. Since it is portable, you take it wherever you need it. Powerful, quiet, 12 Volt 3 inch axial fan has a 6-wing blade mounted in a plastic ring frame. Fan starts automatically whenever the sun shines on the solar panel. Durable - Useful life of solar panel and fan is over 20 years.