A solar attic fan provides ventilation for your attic space. Ventilating your attic lowers your cooling costs by constantly circulating the air, thereby reducing the load on your air conditioner. Attic fans have traditionally been powered by electricity and so been placed on the inside of the attic. Solar attic fans are installed on the exterior of the roof and powered by sunlight. Once installed, the fan will continue to turn as long as the sun shines. Does this Spark an idea?
Size
You need to find the amount of cubic feet of air space in your attic. Do this by measuring first the height of your attic. Measure from the floor to the crown or peak. Then measure the width of your attic across the floor and the length of your attic from end to end.
Multiply the height by the width. Divide that number by two and then multiply the result by the length of your attic. The final number is the cubic feet of air space.
The power of the solar attic fan is measured by how many cubic feet of air it moves per minute. You would need a fan that will move the air capacity of your attic every six minutes. That means the fan circulates the air so that every six minutes you have a 100 percent fresh air exchange.
Fan Rates
The size of a solar attic fan is rated by CFM or cubic feet a minute or how many cubic feet of air the fan moves in one minute. If you have 6000 cubic feet of air space, you need a fan that would move 1000 cubic feet per minute, or a fan rated 1000 CFM.
Installation
Once you've determined the size fan you need, you can install the device. Ideally, you should install the fan on the side of your roof with a southern exposure. However, many solar fans are equipped with moveable panels that allow you to install the fan and set up the solar panel so it faces south.
The fan should be positioned in the middle of the roof and close to the peak. This optimizes its current throughout the attic.
Remove the shingles from the area in which you intend to install the fan. Cut a hole in the roof to accommodate the flashing around the fan. The hole should be between two rafters.
Lay a bead of caulk around the hole in the roof and on the flashing of the fan. Insert the fan into the hole and replace the shingles in the area around the fan.
Check the fan in the interior of the attic. The fan should be securely seated in the hole. If the sun is shining, the fan should be turning.
