Accurate performance characterization for indoor photovoltaics

Indoor photovoltaics (IPV) offer a sustainable solution for powering Internet-of-Things smart devices, driving a surge in IPV research. However, the diverse indoor lighting conditions employed in IPV studies pose unique challenges for accurate performance characterization and benchmarking, often obscuring genuine performance improvements and leading to inaccurate conclusions. This work provides a comprehensive, quantitative analysis of these challenges through experimental characterization of IPV devices spanning a broad performance parameter space, including crystalline silicon, amorphous silicon, perovskite, and organic devices. We demonstrate that many of these issues introduce unacceptable error levels in IPV performance parameters, with the angular interplay among the test light source, measuring device, and IPV device being particularly detrimental under diffuse indoor illumination. To address these challenges, we evaluate practical protocols to mitigate such errors. Furthermore, we highlight the strengths of the reference cell method in enabling reliable and seamless interlaboratory comparisons, thereby advancing IPV research.