The Rocsta is over 7 inches long, less than a half inch thick, and just over 2 inches wide, making it slightly larger than most competing solar chargers out there. Though it has a unique, outdoorsy design, you probably won't want to go on a date with the banana yellow Rocsta dangling from your belt by its built-in carabineer. (Unless you're dating a crunchy-granola type in which case the Rocsta might score you some points.)

Since solar chargers need to directly face the sun to harness its energy, hooking the Rocsta onto your belt really isn't an optimal position for absorbing light. Later when we spread out a blanket in a meadow and lay the Rocsta flat, a red light on its face lit up to indicate that it was charging. You can also power the charger by connecting it to your computer by an included USB cord or by plugging it in via an optional $16 wall charger.

To connect to gadgets, the Rocsta uses easy-to-find iGo tips. The model we tested came with three iGo tips for Samsung, LG and Nokia phones along with micro and mini USB tips. There was also a female USB tip that we connected to Rocsta's integrated charge-out cable and then attached to our iPhone cord. It seemed a little jerry-rigged but it worked. After 2 hours of getting powered in the sun, the Rocsta took 30 minutes to charge our iPhone 4 to 25 percent power status.

While that may sound underwhelming, one of the Rocsta's best features is the power retention of its lithium ion battery. According to Solio, the device can maintain a charge for up to a year. In our testing, we saw no drop in power after the Rocsta sat on our shelf for a week. The device verifies power levels by flashing a green light after you press the Start button on back. Each flash indicates a 20 percent power level with five green flashes signaling 80-100 percent power.

So if you think you're going to need some extra juice on your next field trip, power the Rocsta up before you head out and you'll be charged all day.

WIRED Built with a tough thermoplastic exterior. Included LED light tip turns device into a flashlight. Wear it on your belt on Earth Day and you might add a notch to the old bedpost.

TIRED Additional iGo tips cost $10 a piece. Charging through glass reduces efficiency. Is that a 7-inch yellow Rocsta in your pocket or are you just happy to see me?

• Manufacturer: Solio
• Price: $69

Authors: Dan Havlik

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