Dust-induced transmission attenuation in solar photovoltaic modules: A simplified theoretical model

• Transmittance models for normal and non-normal solar incidence are developed. • Single-layer and multilayer deposition impact on module transmittance is considered. • Theoretical model prediction and experimental result have relative errors below 7 % • Transmittance of a soiled module increases with increasing particle size. • Increasing dust deposition and incidence angle decrease soiled module transmittance. Dust deposition on photovoltaic (PV) module surfaces reduces transmittance. This results in a decrease in incident solar radiation and, consequently, a reduction in power generation. Investigating transmittance attenuation caused by dust deposition is, therefore, crucial for accurate power forecasting and the development of optimized cleaning strategies. The main contribution of this paper is the proposal of several transmittance calculation models for soiled PV modules. These models clarify the relationships between transmittance and dust accumulation, particle size, and solar incidence angle. The models closely match experimental results, with relative errors of less than 7 % under identical conditions. This confirms their validity and enables reliable predictions. After validation, the models were used to examine how the dust accumulation amount, particle size, and solar incidence angle affect transmittance. The key results show that transmittance decreases as dust accumulation increases. Specifically, for 30 µm particles, increasing dust from 1 g/m 2 to 20 g/m 2 yields transmittance attenuation rates of 35.1 %, 44.2 %, 45.7 %, and 63.1 %, as predicted by models I, III, V, and VII, respectively. Additionally, the transmittance increases with increasing particle size, but at a diminishing rate. Increasing the solar incidence angle causes the transmittance to decrease gradually at first, then sharply after 60°. For a dust accumulation of 5 g/m 2 and a particle size of 30 µm, the module transmittance decreases from 0.869 to 0.849 and then to 0 as the incidence angle moves from 0° to 45° and finally to 90°. This demonstrates the importance of module orientation for maximizing energy capture and sustainable performance.