I live in sunny Spain, so there's no problem charging gadgets with solar energy almost all year round. The problem has been cost and practicality. Until now. For the past month or so, I've been testing the Changers solar charger, a rugged, lightweight solar panel and battery.

The solar panel itself is tough, light and flexible. It has a similar feel to those bendy plastic cutting boards from Ikea, only smoother and slightly stiffer. My review unit has dropped from the window several times, and I've never worried about it breaking. In fact, I plan to strap it to my bike's rack on my next ride to keep my gadgets juiced while in transit.

The panel has a hole at each end for hooking, tying, bungee-ing or screwing in the supplied suction cups. The cups hold it to a window – or not, if you have windows as dirty as mine. One style note: The back of the panel has a bunch of eco-hippy slogans printed all over it, which you (and visiting guests) will see when the panel is hanging in a window, collecting rays. (Nils from Changers wrote me to say that the text-bedecked version is a special edition which won;t go out to regular buyers. Thanks, Nils!)

A cable runs to the battery pack, and plugs into a port marked "Sun" – cute! Depending on the intensity of your sunlight, it should take an average of four hours to reach a full charge. My results have been different this winter, though. With the winter sun filtering into my dusty apartment for only a few hours a day, I've been getting just three-quarter of a charge daily.

Once charged, you can plug any USB-powered device into the system for power. The Changers comes with a bag of adapters, none of which fit any of my gadgets (curiously the pack doesn't contain a Micro B USB adapter, the kind used by the Kindle and many others). Fortunately, the standard USB port lets you plug in your own cables. UPDATE: I realized that in my haste to unpack the device all those weeks ago, I tossed aside the microUSB cable which comes with the kit in order to hook it up to your computer.

Usefulness varies. While the system will charge an iPad 2, the charger dies before the iPad reaches even a 25 percent battery charge. On the other hand, it will recharge a JamBox speaker over and over, and still retain most of its charge.

Finally, there's the "Changers" element of the system, which lets you track your energy use online. This is something of a pain, as you need to have a helper app running on your computer, and the website has forced me to log in fresh every time. You earn points for every gram of carbon dioxide saved, and in the future you'll be able to exchanges these points for various services – a weekend in Portland, perhaps?

At $150, the Changers kit isn't a bad deal, and it's light and sturdy enough to withstand a camping trip. It's also convenient, and you do feel good using it. Indeed, I haven't charged a JamBox or Kindle from their main power adapters since it arrived. If only it didn't have all that hippy-babble on the back.

Changers Store [Changers]