Wagan EL8207 18W Solar E Panel Sun power solar panels are 35% more efficient than conventional solar cells and convert around 27% of available sunlight into electricity Sun power solar panels perform better when sunlight isn't as strong and absorbs a broader range of wavelengths; so it charges for a longer time per day to reach peak performance Smart-charge USB port enables full speed charge by automatically detecting maximum current draw from your electronics and provides universal capability with your electronics 5V 2.1A USB output is compatible with tablets, e-readers, smartphones, mp3 players, digital cameras, etc., plus includes a micro-USB cable Hanging loops or grommets allow this 18w solar panel to be attached and hung from a backpack or other object, plus a built-in splash-proof storage pouch holds batteries and other accessories