the voltaic™ backpack is a mobile power source, designed to charge your gadgets without tying you to a power outlet. embedded in the back of the bag are three tough, light weight, waterproof solar panels, which generate up to 4 watts of power. inside the bag is a battery pack. the battery stores energy so it is available when you need it, not just when the sun is up. powerful enough to charge most portable electronics (other than laptops) including: cell phones, cameras, GPS’s, PDA’s, even ipods. link to voltaicsystems