This solar panel is made of single-crystal silicon material of A level that performs high solar energy transformation efficiency at 19%?and it built-in a diode of preventing the backflow. Of course it?s waterproof, and other advantages like small in size and convenient to carry? using immensity casing to design. This product be designed to let people charge their device that use USB interface. In those bright summer days with clear sky and big sun, a mobile phone will be full charged within two to three hours. If I were you, I would took it when I was camping or joined in other outdoor activities. What a useful tool! Tip?you?d better to add a lipo charger
module if you want to charge your mobile phone.