Julian Sarokin in his website posted a small video on how to use a solar panel for powering a raspberry pi. It is a very simple guide and and it misses a lot of stuff but if you want something quick it will give you the idea. For sure there are other more efficient ways to achieve a better result but they involve electronics and soldering knowledge. The parts that Julian used:
Solar Panel (6w, 2V): https://www.adafruit.com/products/200
DC / LiPoly Charger: https://www.adafruit.com/products/390
LiPoly Battery (3.7V, 2500mAH): https://www.adafruit.com/products/328
DC Power Adapter (2.1mm): https://www.adafruit.com/products/369
Powerboost 500 (5v USB @ 500mA): https://www.adafruit.com/products/1903
