I happened to go back a bit in the Engadget archives and found
this great post about the
Voltaic Solar Backpack. This is one of those items that, chances are, you
will NEVER own, but which is cool to know exists. The bag basically contains a solar panel embedded in the side, which
will help power up and charge all manner of electronic devices you may, or may not, want to bring along on a camping
trip. The backpack charges using a series of solar photovoltaic cells, which have become much cheaper to
manufacture and more efficient, at least since the days when you’d have massive banks of these things on your roof.