There is no rechargeable battery in the fan, if you need the fan works at night, you can use a power bank.
When the sunlight is strong, the fan works quickly, when the sun is not strong enough, the fan can run low or even does not work.
Can use on cloudy days or indoors with USB charging.
Works when connected to the solar pane and can be used alone to be connected to the USB port of the computer.
PORTABLE 4-INCH COOLING FAN: Perfect for car, caravan, greenhouse, shed ventilation, motorhome, campervan, boat, home