the problem would be how to transport, use and keep the phone unit safely and inconspicously and charge it with daylight at the same time. does this mean we have to have the mobile phone exposed to sunlight (or any light source for that matter)?

you can use any soure of light.

this idea would be very jelpful if implemented. imagine how convenient it would be to have solar-powered cellphones! just like solar-powered caluculators, the phone would be able to store the energy for use throughout the day, so you don't have to expose the phone to light all the time. i wouldn't mind having a solar-powered cellphone.

Yes, this will definitely be a plus in conserving energy and be of a time saving work. Imagine, you can charge your cellphones during daytime and be able to make use of te sunlight as its source of battery! you dont even have to worry about briging your charger with you all the time.Hmm..but what if you are indoor the whole day? what do you have to do to charge the cellphone and how long should it stay under the source of light/ sun to get full charged?

There is a company out there that has the technology to allow plastic to absorb light. In other words a plastic solar panel. They are planing on making cell phone and laptop cases out of this plastic so they will be constantly charging.