Photovoltaic cells for micro-scale wireless sensor nodes: measurement and modeling to assist system design

摘要

Energy harvesting enables perpetual operation of wireless sensor nodes by scavenging energy from the environment. Light energy harvesting using photovoltaic (PV) cells is preferred as they offer the highest volumetric power output allowing nodes to be as small as possible. However, their power output can be spatially and temporally-variable. This work investigates the performance of cm^2-scale PV cells, and reports on a new measurement and characterization platform. Results show that micro PV cells perform differently from large panels: power is not simply a function of area and light levels, and manufacturing variability can be a major issue. The method presented enables the rational design of micro-scale systems, including their maximum power point tracking circuits, and the evaluation of techniques for energy-neutrality (such as workload throttling) at design-time.