How Does an Attic Fan Work?

Summer is here! Are you ready to tackle the heat in your attic? Studies show that attic heat can rise to almost 160˚F in the summer.

Many householders use attic fans instead of air condition units to help keep the temperature in the attic down.

  • A thermostat switches the fan on and off. It also acts as a ventilator to expel hot air.
  • The vents and fan work together to keep the attic air cool and moisture-free.
  • As the heat rises, the attic fan works to expel the hot air and replace it with cool air.
  • The vents in the fan open up to let the cool air circulate.
  • The fan spins to push out the hot air and balances the heat levels in the attic.

Homeowners can rely on attic fans to eliminate moisture, keep the air cool and dry, and improve comfort when using the attic.

To help beat the summer heat, why not consider a solar attic fan?

How does a Solar Attic fan Work?

Solar attic fans get their power from direct sunlight instead of electricity.

  • Solar attic fans use the heat from the natural sunlight to power their motor.
  • There’s no additional utility charge. Solar energy is free.
  • It’s a motorized venting system that does not need electricity or extensions to your roof structure to work.
  • Solar attic fans depend largely on sunlight to get enough power to operate. As the sunlight penetrates the solar cells, the fan blades begin to turn.
  • They work with your existing vents to help move the hot air out and draw the cool air inside the attic.

Reduces Energy Costs

Solar attic fans take the hot air out of the attic and bring in cooler air from the outside. They keep the air cooler by allowing your air conditioning to work less hard to keep the air dry. It’s a good way to keep the house cool without relying heavily on the air conditioning or gas.

Maintains Consistent Air Flow

  • Solar attic fans also regulate the humidity and temperature in the attic and promote consistent airflow.
  • Cool air can also trickle down into other areas to make the house cooler.
  • The cool air from the attic fan melts frozen snow on the roof.
  • The air from the fan can prevent leaking and damage to the rafters from snow damming.

Helps Promote Cleaner Air

Mold and mildew can build up from moisture in a hot attic. Solar attic fans push the moisture out, keep the attic dry and reduce the growth of mold and mildew. Less mold and mildew can extend the life of your roof, as build-up can cause your wood to rot quickly.

Low or No Maintenance

  • Solar attic fans are easy to set up and install if you are familiar with carpentry.
  • While the initial cost may be high, most states offer tax rebates for installing them.

Getting the Most out of Your Solar Attic fan

Keep Your Vents Uncovered

Insulating your attic walls will reduce your energy costs, but be careful not to cover the gable or soffit vents. When you cover the vents, you block the cool air from outside flowing into the attic. The solar attic fan will then draw the air from the air conditioning unit to keep the air cool. The air conditioning unit will use more energy to maintain the cool air and will increase your electricity cost.

Keep the Windows Open

You can increase the airflow in the attic, by opening the windows while the fan is working. The solar attic fan will release the hot air, send it outside, and take in the cool air from outside. Open windows let the fan brings in cooler air into the attic, and will circulate the air throughout the home.

How the Solar Attic Fan Works in the winter

During the winter, the solar attic fan draws in the cold air through the vents from the outside and lessens the incidence of ice-damming. Snow falling on the roofs, gutters, and eaves can pool and then re-freeze. Ice dams form up and can damage the roof by seeping under the wooden structure. Warm air from the attic fan circulates and helps melt the ice dams.

How Solar Attic fan Works in the summer

The temperature and humidity are higher during the summer months. The attic fan works to push the hot air out and bring in cool air to reduce moisture.

It Protects the Roof Structure

As trapped heat penetrates, it creates moisture that can weaken the wooden rafters in the roof. Moisture creates mold and mildew that can contaminate the air quality and cause the boards in the attic to rot. Less moisture protects the roof and promotes cleaner air in the attic. Any attempt to protect your roof will add up to savings in maintenance and repairs in the long run.

Added Benefits

Heat and cold can build up quickly and become trapped in the attic. They create excess moisture and humidity.

  • Studies show that solar attic fans can lessen the temperature in the attic by almost 40˚F.

The heat from the roofing material can penetrate and bear down on the attic, making it uncomfortable.  In the winter, snow piling up on the roof can make the room colder. Contrasting weather conditions during the winter and summer months can drive up your energy costs.

  • Research suggests that solar attic fans help reduce monthly electricity costs by up to $30.00 and air conditioning use by almost half.

Here’s the Scoop:

Research shows that good ventilation reduces moisture and the amount of water vapor in the room. Good ventilation keeps the room cool and decreases mold and mildew.

Promotes Greener Economy

Since solar attic fans work by sunlight, there are no additional electricity or gas costs.

Safe and Economical

A solar attic fan is an affordable, easy way to keep the attic cool, save energy costs and protect roofing material. Your heating, ventilating, and air conditioning system can be under pressure when heat builds up. If there’s little ventilation in the attic, heat becomes trapped in the insulation and ductwork, which makes the air conditioning work harder to cool the room down.

The solar attic fan helps regulate heat in colder months and makes the air conditioning work more efficiently.

  • Solar attic fans tend to pull less air than standard attic fans. They help improve the overall energy efficiency in the home.
  • They set up on the roof, and work along with your existing vent to circulate cool air around the attic.
  • Some studies suggest standard attic fans may be more expensive to use since they can create pockets of pressure.
  • Pockets of pressure can cause the fan to utilize cool air from the air conditioning which drives up energy bills.
  • Also, the air pockets can cause the fan to pull harmful gases into the room and circulate them around the home.

Increases Comfort Levels

Solar attic fans help increase comfort levels in the attic by keeping the air dryer and cooler. Cool air circulating will help clean the atmosphere and improve the overall environment. Cooler, more bearable temperature protects the attic structure from ice damage in the winter.


With solar attic fans, there’s no need for electricity or costly wiring to set up.  They are easy to set up, but the cost of the fan and panels may be expensive. However, most states offer tax rebates for installing solar attic fans.

Protects Your Roof

The solar fan will help regulate attic and outside temperatures for cooler Air inside. It helps reduce damage to roofing materials caused by moisture build-up. The cool air helps balance the moisture levels to prevent leaks and protect the roof from rotting. It also helps reduce mold and mildew that can damage the attic structure.

Which Solar Attic Fan is Best For You?

The right solar attic fan will depend on the shape of your attic structure. You can choose the type of fan that will fit your ridge, gable, or soffit vents.

Get the Right Fit

Depending on the size of the attic, one solar fan may not be enough.

  • For low-angle roofs, one fan may be enough. However, for higher-pitched roofs, or attics between 2,000 and 3,000 square feet, you may need two or three fans.
  • For attics between 1,800 and 2,000 square feet, a 20-25 watt fan should be adequate.
  • For attics over 2,500 square feet, a 30-watt fan may suffice.

Roof-Mounted Solar Attic Fans

Roof-mounted solar attic fans are more suitable for flat or pitch roofs. If the attic space is small, a 16-watt panel may suffice. Install roof-mounted attic fans at the back of the roof, preferable underneath the ridge. It can also sit near the center of the main part of the attic. They draw cool air through the vent in the roof closest to the overhang. In turn, the cool air pushes the hot air outside, making the attic cooler.

Gable Mounted Solar Attic Fans

Place the gable mounted solar attic fan at the end of the house farthest away from the direct wind. Position it on the gable vent. With gable-mounted roofs, there’s no need to cut holes into the roof. You can also install the remote panel on the roof away from the fan.


Solar attic fans are cheap, affordable, and easy to use. They rely solely on sunlight and require no additional energy costs. Solar attic fans help balance the cold and hot air to promote consistent airflow. Consistent airflow helps regulate moisture levels and reduce harmful mold and mildew. They help improve and reduce energy costs in the home. They regulate the air quality, improve comfort levels and protect your roof from damage.