XD Design solar chargers can charge mobile devices without having a power socket. One can simply capture energy from the sun and store the power for later. In addition to capturing sun energy all XD Design solar chargers come with a USB cable which can also charge up the battery. This cable is also necessary when the built in battery is completely empty. Because the solar chargers needs real power to wake up the battery again. The solar charger will be full after collecting 14-22 hours of sunlight. For the best results one should expose the solar chargers to direct sunlight.