Here's another patent from Apple. They are envisioning solar powered devices. Patently Apple has revealed a patent for a solar-powered iPhone.
Since the iPhone's battery sucks, this seems like a better solution to solar-charging than just sticking a bunch of solar panel on the back of the device. The company is planning energy collecting cells that are hidden underneath the display. The iPhone won’t look much different but whenever in the sun it will juice itself up.
The recent change in the iPhone backside substrate to a non-metal surface has also opened the doors for the solar panels.