While power from the sun is readily available, its usage and practicality are still a mystery to many. Solar chargers allow you the freedom to unplug from the wall and use natural light. Many battery chargers are continuously recharged via an array of photo-voltaic panels that convert light into free energy - meaning you can charge your devices whenever, wherever.
Of course, if there's no light available or you're in a terrible rush companies like Voltaic, which makes the battery packs for the backpack on the right, also include automobile and world voltage AC charging adapters. You will have to spend a bit more for solar powered bags, but the small single device chargers (say for your smartphone or iPod) cost about the same as regular travel chargers and will save energy, time and money in the long run.
Solar chargers used to be clunky devices that were best for home use, but now there are some great, moderately priced chargers that are small enough to fit in your suitcase and chic enough that airport security won't think it's a homemade bomb. If eco chic is your thing you can even charge your gadgets with a solar powered swim suit. Talk about hot.