Supercapacitor-based hybrid storage systems for energy harvesting in wireless sensor networks

This paper investigates a power management architecture based on a hybrid accumulator system that utilizes the supercapacitor cell as storage element for energy harvesting applications. The supercapacitor guarantees a longer lifetime in terms of charge cycles, it presents itself as a ¿green¿ technology compared to batteries and it has a wide range of operating temperature. The drawbacks of this type of solution are the low energy density and the leakage current that reduce the performance for very low power applications. In this paper a photovoltaic scavenger based on the supercapacitors is investigated and it can work only with supercapacitors, or together with the lithium battery cell in order to obtain a good compromise in terms of energy density and lifetime. A dedicated power management strategy is also proposed. Experimental results with a 5 W photovoltaic energy source are reported.