Solar Attic Fans - They're a Breeze!

If you’re looking for an inexpensive way to use solar energy in your life, consider using a solar attic fan to exhaust hot air from your attic. These fans are powered by electricity generated by solar electric panels (a.k.a. PV modules). The solar module may be integrated with the fan or physically separate from it and connected only by an electric wire, which can allow for the best placement of each component. Installed on a rooftop or in an end-wall or gable, solar attic fans operate whenever there’s sunlight striking the solar module.

How They Work

Using electric fans to cool off an attic space isn’t new; many households already use fans to expel excess heat that builds up under the roof. These fans are usually connected to household AC power using a manual or thermostatic switch. The principle is simple: air trapped under a peaked roof bathed in sunlight becomes very hot. By conduction, that heat passes into the rooms beneath through their ceilings, increasing the temperature of that whole story of the house. The result is either discomfort or an increased use of power-hungry air conditioning. By exhausting hot air from the attic space, attic fans reduce the need for air conditioning, saving money and energy in the process.

Solar attic fans simply replace the grid energy source with free solar energy. They run when you need them most-- when the sun is shining and adding heat to your house. They eliminate the need for AC wiring because the fan comes with its own power supply, a small solar panel wired directly to the fan; and they can be installed anywhere that full, unobstructed sunlight is available for their solar modules.

What’s Available

Some models are self-contained units that must be installed on a rooftop where they can both receive solar power and best vent the attic or building space. Other models allow for the fan and the solar module to be installed separately; in these models, the fan is typically mounted between framing studs on an end-wall or gable wall of an attic, usually where a passive vent hole already exists. The fan is aimed to blow air out of the attic, thus drawing cool air into the attic from other vent openings. The solar module powering the fan is typically installed on the rooftop or bracketed to an overhang. The module and fan are then connected using the supplied electrical cable. All solar attic fans have DC motors that run “solar-direct”--- that is, directly from current produced by the solar module as it converts sunlight into electricity. That means daytime use only, but that’s also when the attic gets the hottest and venting is most needed.

Additional Benefits

Solar attic fans can provide year-round benefits, even in the wintertime when excessive heat is not usually a problem. Wintertime ventilation can help to prevent moisture build-up in the attic space that might otherwise dampen insulation, reducing its effectiveness, or contribute to mold growth,  peeling paint or flaking plaster.