A system-level study of indoor light energy harvesting integrating commercially available power management circuitry

Abstract

Abstract

With the development of sustainable and energy-efficient buildings and cities, scavenging indoor light energy to power Internet of Things has become an increasingly attractive solution. However, the energy that can be harvested from an indoor light environment is limited compared to natural, outdoor sunlight, emphasizing the importance of efficiency of the entire energy harvesting system rather than that of individual harvesters. Power management circuitry plays a crucial role here but there has not been a system-level study for different power management schemes when connected to both harvesters and batteries whilst working under real lighting conditions. This study evaluates four integrated indoor light energy harvesting systems containing two distinctive types of photovoltaic cells connected to a switched capacitor (SC) and an inductor-based (IN) boost converter, respectively, as well as a Li-ion battery. Charging efficiencies of the entire systems, in addition to those of individual components, are assessed. Results suggest that for an indoor light energy harvesting system, although the IN converter tends to be cumbersome, it provides unbeatably high and stable battery charging efficiency across a broad range of light intensities compared to the SC converter even though the latter is specifically designed for low-power applications competing with the IN counterpart.