There's a fascinating look, from Laptop magazine in the USA, embedded below, at a new solar charging technology from Wysips. Using an ultra-thin (less than 100 microns) photo-voltaic layer on top of the usual smartphone touchscreen, it can deliver up to 250mW of power. Although it's unlikely that such a layer could eliminate the need for traditional charging, the extra top-up factor could well double effective battery life. The technology will be launched officially in 2012 and may be in devices within a couple of years.

From the Laptop article:

When we asked whether a Wysips film would affect touch accuracy, president Ludovic Deblois said that it wouldn’t have an impact, even if it was a glasses-free 3D screen. In the video, you can see that the voltage meter shows that the Wysips film is sipping energy when placed near a lamp, but it could also be light coming through a window. When Deblois covers up the film, the meter reading dips. Wysips also showed us an prototype film overlaid on the iPhone 4, but it was a bit dark. A final product would be directly integrated into the LCD.

According to Wysips, the technology will fully charge a typical cell phone battery in 6 hours of outdoor light, but it would take longer indoors to fully juice a handset. With the second-generation technology that will arrive next year, you’ll have enough juice for 30 minutes of talk after just an hour of charging.  While those times seem long in comparison to typical AC or USB charging, this is all done with light and occurs seamlessly while you use the phone. Plus, the phone is always sippingenergy–unless it’s in a pocket or purse.