The solar panel uses the photoelectric effect to harvest energy from the sun in order to generate the power necessary to run the fan. Switches are then used to switch between charging, using the solar panel to run the motor, or using the battery to run the load. A solar fan is a mechanical fan powered by solar panels. The solar panels are either mounted on the device or 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.