This white paper introduces Lightricity’s LightBox Indoor Light Simulator, a benchtop system designed to help engineers, researchers, and product developers test indoor photovoltaic cells and light-powered sensor devices under controlled, repeatable conditions. It explains the need for reliable indoor PV characterization as more IoT devices move away from batteries and toward energy harvesting. The paper positions the LightBox STD and LightBox XL as standards-based tools aligned with IEC TS 62607-7-2:2023, capable of testing across a wide range of indoor light levels, with calibrated LED light sources, software-controlled measurements, and validation work involving the UK’s National Physical Laboratory.