More than meets the eye - A portable measurement unit for characterizing light energy availability

Characterizations of environmental energy availability and properties provide important insights for designing energy harvesting nodes and developing energy harvesting adaptive systems and algorithms. Previous characterizations of light energy availability provided baseline estimates of the total available energy that could be harvested by a crystalline silicon solar cell. However, these measurements did not consider the spectral composition of the incident light. In this paper, we present a method and a proof-of-concept implementation for obtaining information about the spectral composition of the incident light. LightBox, a portable measurement unit, determines the light source, measures the incident irradiance, and calculates the amount of energy that would be harvested by two different harvesters: a crystalline silicon solar cell and an amorphous silicon solar cell. To the best of our knowledge, LightBox is the first portable irradiance measurement device that considers the spectral composition of the incident light. Our method and proof-of-concept implementation are an important step toward better characterizing environmental light energy availability for energy harvesting nodes deployed in a wide range of environments. The insights from this data will enable the development and wide deployment of energy-aware algorithms and systems.