Light scattering materials are important for solar energy applications, but measuring their transmittance accurately can be tricky. A study looked at how to quantify the light loss when using an integrating sphere to measure thick scattering samples. By comparing measurements with a ray-tracing simulation, researchers found that commercial integrating spheres often underestimate the true transmittance. This research aims to improve the methodology for characterizing scattering samples, which is crucial for designing efficient solar energy systems.