Ambientech has a couple of mobile solar charging systems in the form of the SolarFold and SolarFan. As you can tell by the image above, the former will fold up like one of those heat-resistant visors for vehicles, while the latter can be rotated and kept away neatly similar to a hand fan. These are touted to be the first mobile solar charging systems in the world that utilize light-gathering spherical solar cells. Should sunlight be insufficient, then you can always use a USB charger instead.
Next Story: Data Logging Shirt