Eric Dennis was working on a documentary in the wilderness and needed a way to keep his gear charged without going back to civilization to find a power outlet. His solution for keeping his camera, lights and computers running was to use Brunton Solar batteries. They may take a bit of time (between 5 and 12 hours) to charge, but this is much cheaper than purchasing the amount of batteries required for the amount of time they we’re shooting.
Obviously, there are issues with matching the correct voltage, but that can be solved by using a voltage converter. I would recommend being absolutely certain your voltage is correct before you start plugging things in. Incorrect voltage can destroy electronics very easily.
Check out Planet5D’s post for more info.