The fan runs when plugged to the solar panel. And it can be used alone by plugged into computer USB port. When plugged to the solar panel, how the fan works depends on the sunlight. When the sunlight is strong, the fan works fast. When the sunshine is not strong enough, the fan may work low or even does not work. There is no rechargeable battery in the fan. If you need the fan works at night, you can use a powerbank. Solar panel Power: 2.5W,5V Panel Size: 150*130mm Application: Charger for powerbank, MP3 and eletronic products. Feature: Waterproof Mini Fan Size: 4 inch Power: USB Plug 5v USB cable length: 120cm Color: Black Material:metal Package Contents: 1 * Solar Panel 1 * USB 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.