Solar-powered fans use a solar panel to generate the electricity needed to turn the fan motor. One common application is for attic ventilation. Because the solar panel provides the most energy when the sun is hottest, the fan moves more air at the time of highest need.
Solar panels consist of photovoltaic cells. As light hits the solar panel, it forces electrons to move through a circuit, creating electrical energy. Each photovoltaic cell consists of two layers, which have positive and negative charges like a magnet. The manufacturer then links enough of the cells together to produce a panel large enough to provide the power to turn the fan.
Homeowners often prefer using solar fans for attic space because there is no need to add electrical wiring to power the fan. Instead, the solar panel provides about 10 volts to operate the motor and turn the fan blade. Because the installation is on the rooftop, many homes provide the unobstructed sunlight the fan requires to operate. As the sun is the primary reason for the buildup of heat in the attic, the fact that the fans do not operate at night is not a problem. In applications where the fan needs to continue turning after dark, manufacturers add a battery to store electricity produced by the solar panel.