When connected to the solar panel, the fan can run; and can be used alone by plugging into the computer's USB port. When connected to a solar panel, the way the fan works depends on the sunlight. When the sun is irradiated to generate hot air, the fan immediately rotates to dissipate heat in time, ventilate, save the trouble of pulling wires, and it is and more convenient. There is no rechargeable battery in the fan; if you need the fan to work at night, you can use the power pack. Specification: Solar panel chip: Polysilicon Solar panel power: 5W, 6V Panel size: 14.5cmx14.5cm/5.71x5.71in Mini fan: Size: 4 inches Power supply: USB plug, 5V USB cable length: 70cm/27.56in Material: Metal colour: black Package Contents: 1 x Solar Panel 1 x Fan Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.