Maximum Power Point Considerations in Micro-Scale Solar Energy Harvesting Systems

Maximum power point (MPP) tracking is a technique to maximize the amount of power harvested from energy transducers such as solar cells. MPP tracking presents new design challenges when used in the context of micro-scale energy harvesting systems, where the area dedicated to solar cells is small (in the range of sub or a few cm(2)) and hence, the power output is in the range of a few mW. This paper provides an overview of several low-overhead MPP tracking approaches that are attractive for micro-scale solar energy harvesting. These include: design-time component matching method, fractional open-circuit voltage or fractional short-circuit current method, and variants of the generic hill-climbing approach. We also illustrate using a simple case study, how MPP from a full-system perspective may differ from the MPP of the photovoltaic module itself in micro-scale harvesting systems.