Solar Powered Attic Fan

Many manufacturers now offer solar powered attic fans to ventilate attics and help keep attics cooler. Solar powered fans rely on a small (typically 10- or 20-watt) solar panel to power a DC motor when the sun is shining. The fans, which exhaust air at a rate of 800 to 1200 cfm, are installed with intake vents (such as soffit and gable vents) to provide high-capacity powered ventilation without electric operating costs. Most vents are mounted high on the roof, near the ridge, and combined with soffit or gable vents for balanced intake and exhaust air streams. Solar powered gable ventilators are also available.

Compared to powered vent fans, there is no need for electrical wiring, and a solar ventilator uses no electricity (hence avoiding operating cost). Although equipment costs are greater for solar powered attic fans than conventional powered fans (about $200 more), the cost to bring electrical wiring to the attic to supply a conventional ventilator closes the gap on installed cost.

Ventilation is only provided when there is ample sunshine to power the fan motor. The highest solar insolation (and, hence, fan speed) typically coincides with the time of greatest need for attic ventilation.

If there is inadequate attic intake air and poor sealing between the conditioned space of the home and the attic, powered attic fans can potentially draw air from the house into the attic. Not only can this compromise energy efficiency, it can increase the risk of attic moisture problems as well as increase the risk of drawing the byproducts of combustion into the house (a process called backdrafting).

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2/14/10 - Here's an update for you...

Derek Odette of Attic Breeze was kind enough to email me some great information. According to Derek, Attic Breeze is the only solar attic fan on the market that is Florida Product Approved and has a LIFETIME WARRANTY. Worth checking out, don't you think?