The kit includes pre-soldered solar panel with switch and sound buzzer alarm. When you put the solar panel in sunlight, the sound buzzer produces beep-Alarm-Sound or you can say when sunlight falls on solar panel, it produces sound alarm. 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.