Solar-powered phones? Nokia says forget about it
In these times of super big screens going to 4.7 inches and even 5.3 inches on the Samsung Galaxy Note, and LTE radios draining up power, battery life is becoming of paramount importance for smartphone users. One technology we’ve been very curious about is solar charging. The prospect of just using the sun’s energy to juice up devices is not new, but it seems like one of the easiest and most efficient ways to increase a phone’s battery life.
Nokia has done some research on solar charging, even built a prototype phone (and based on the pictures it didn't have a huge screen to drain battery), but sadly concludes that the solar charge it got is not enough for daily usage. The Finns sent out five testers with the prototype phone in different parts of the world - from the African country of Kenya where the sun shines bright nearly all year long, to the Arctic Circle where the angle of the sun is pretty low.
source: Nokia Conversations