1. Please charge it under STRONG sunlight, do not charge it in cloudy day or the place through glass(e.g a window or car)

2. Solar charging is designed for emergencies, not a primary source of charging due to the compact solar panel size and sunlight intensity, it could take 21 hours under direst strong light to fully charge(there are 7-8 hours of sunlight per day). So we highly recommend charge the solar charger via an adapter or computer, which only take a few hours