These are fine for slowing discharge while using your phone, maintaining charge, or very very slowly charging up your phone while not in use. I'm happy enough with the purchase, but had hoped they would have provided a little more power.
Solar surface of 30watt version is 632cm2 which leads to a max power of 10,1watt instead of 30 offered. Furthermore the ends of the solar panels are covered by the wrapping so maybe below 10 watts. Soldering in the Usb port is poorly done and how should it be waterproof if there is a hole in the Usb housing? You can charge a phone with it, but its simply not as advertised.