The Teardown Squad over at Tech-On took the latest solar-powered handset offered by Sharp for a test drive and have reported their detailed observations both Here and Here. KDDI released the device, also available via SoftBank Mobile, in Tokyo on June 9th. The jist of their testing seems to indicate that, while it does indeed work, the time to get free juice takes somewhat longer, like 85-mins charging for 5-mins of talk, than suggested. To be fair, as with most first wave products over years, surely the performance will improve with future revisions.
In the experiment, the icon indicating one-minute talk time was not displayed even after 10 minutes of charging. In the end, it took about 40 minutes for one-minute talk time, 60 minutes for three-minute talk time and 85 minutes for five-minute talk time. In other words, to have talk time of one minute, it took several times longer than 10 minutes, the charging time Sharp announced.