A solar fan is a mechanical fan powered by solar panels . The solar panels are installed independently. Solar fans mostly do not require secondary power sources other than solar power , as most of them are used for cooling purposes during day time. Some types are also used for heating purposes. It runs the fastest when it is the hottest outside providing savings on air conditioning costs. 
Attic heat is caused by the sun baking down on the roof surface. This sunlight causes heat transfer, thus transferring the heat into the attic via thermal transfer. The buildup of heat is generally dissipated by normal convection, ie, it is heated up and rises, flowing out of the attic. generally in the eave (soffit) area. However, most of the winds are inadequate at expelling the heat and require the use of a fan. A solar powered attic fan is an effective way to remove heat using only the power of the sun to run the fan. 
Solar powered ATTIC fan – roof mounted
A typical roof-mounted solar attic fan will be effective in removing excessive heat from the attic. When the sun rises, the fan forces hot air out while pulling fresh air in via eave / soffit winds. This exchange of air keeps the attic space from overheating. 
Solar powered attic fan – gable mounted
It is similar to the roof mounted solar fan, except that its installation is a little different. Most attic fans are installed on the roof surface, and most of them are installed in the gables, inside the attic and behind the existing ones. They are mostly installed in places like garages or barnsand other storage places where heat and moisture are usually present. These types of fans are generally included to provide ventilation. Gable Solar Fans are usually installed on the gable close to the ridge and are also combined with air intake and exhaust air vents. The airflow is about sunlight, the airflow will be more resulting in enhanced cooling. It is also capable of lowering the air conditioning costs by cooling the attic. 
In 2007, solar fans were installed on the terminal roofs of Honolulu International Airport, in addition to the mansion of Indiana governor . In 2009 the Indiana State Senate passed a bill to homeowners with solar fans. 
- A solar fan is more environmentally friendly.
- Though the facility INITIALLY May be costlier, in the long term Would it turn out to be Cheaper Because it does not use power from the utility grid and May Provide savings up to 30 percent on air conditioning costs. 
- Risk of electric accidents are eliminated to the solar fan.
- A cordless appliance offers a lot more mobility compared to the standard fans. [ quote needed ]
- List of solar powered products
- Solar cell phone charger
- Solar notebook
- Solar powered calculator
- Solar powered watch
- Solar powered radio
- Solar powered flashlight
- Solar powered fountain
- Solar street light
- ^ Jump up to:a b c “Solar Fan Man Looks to Sun for Solutions” . abcnews.go.com . Retrieved 2011-07-08 .
- Jump up^ “The Types Of Solar Fans For Your Home” . CleanGreen. February 15, 2015 . Retrieved 25 May 2015 .
- Jump up^ “About Attic Ventilation” . EnergyStar . Retrieved 25 May 2015 .
- Jump up^ “It Makes Sense To Install A Solar Gable Fan” . solargablefan.org . Retrieved 2011-07-08 .