Solar energy harvesting strategies for portable devices such as mobile phones

In this paper we present strategies to harvest solar energy for mobile phones. Thereby, we discuss system structures, in which mobile phones act as either active or passive devices depending on an available communication between smartphones and their solar chargers. Both design approaches have their advantages and disadvantages, which we will elaborate in more detail in our analysis. At the moment, conventional solar chargers do not meet user expectations and need substantial improvements. We aim to establish design guidelines to make solar chargers competitive with normal chargers, which are plugged into electric sockets. As a result, we achieve appropriate recharging times for smartphones on the one hand and satisfy user requirements on the other hand.