We might still be anxiously awaiting the arrival of solar-powered cell phones in the U.S., but Japan already has at least one on sale as of June 4. Sharp makes some lofty claims about the performance potential of the waterproof "Solar Phone SH002"—namely that it can provide one minute of talk time or two hours of standby time when charged for ten minutes in the sun. But Tech-On took the phone for a spin and found some different results.
The Nikkei Electronics Teardown Squad set out a switched-off Solar Phone in the sun with zero remaining battery power to see how long it would take to charge. It was a tricky process, since the phone's display kept flipping between "solar power not available" and "charging" when the angle of the handset to the sun was changed. Ultimately, it took the Squad 40 minutes to squeeze out one minute of talk time, 60 minutes for three minutes of talk time, and 85 minutes for minutes of talk time. So while Sharp readily admits the phone's solar power capability is auxiliary to outlet power, it seems like the solar panel is really only useful in emergency situations. The Squad didn't, however, test the phone's waterproof claim.
Both Samsung and LG are planning to release solar-powered cell phones, but the technology clearly isn't advanced enough to be useful in everyday situations. And Sharp's solar panel, at least, isn't too durable despite its purported waterproof capabilities; a seal attached to the module warns "Do not leave it in high-temperature places like in a car. It could lead to heat generation, ignition, deformation and breakdown". In other words, half an hour of forgetfulness on a sunny summer day will cook the phone's solar capability. Perhaps the next big energy revolution in cell phone technology won't be solar at all—Kyocera is working on a kinetic-energy powered phone that derives energy from human interaction.