Optical Scattering and Transmission Characterization of Dust Deposition on Photovoltaic Panel Surfaces

Dust deposition on photovoltaic (PV) surfaces reduces the light reaching the cells. This article establishes a scattering and transmission model of dust accumulation on photovoltaic panels based on the Bidirectional Reflectance Distribution Function (BRDF) model. It analyzes the influence of the dust particle composition, size, quantity, and other parameters on the light-transmission characteristics of photovoltaic panels, constructs an electromagnetic model of dust-accumulated photovoltaic panels, and studies the effect of different amounts of dust accumulation on the scattering and reflection characteristics of the panels. By setting up a scattering measurement platform and using modulated active light sources for illumination, it explores the scattering and transmittance rates of photovoltaic panels under different levels of dust accumulation. A comparison of the mean experimental results from five different positions with the theoretical predictions yields mean absolute errors of 4.23 percentage points for transmittance and 21.28 ppm for the scattering rate. Modulated illumination and lock-in detection were used to suppress ambient-light interference during the laboratory measurements. The combined transmittance and scattering measurements characterize changes in surface soiling at 635 nm and provide a basis for developing site-calibrated optical indicators to support photovoltaic inspection and cleaning decisions.