Dust accumulation significantly reduces the efficiency of photovoltaic (PV) modules. Unlike previous research focused on single modules, this study uses wind tunnel experiments to demonstrate that the installation parameters of PV arrays-such as tilt angle, elevation, and inter-module spacing-induce spatial heterogeneity in dust deposition and particle size distribution (PSD) across module surfaces. Results show that the deposited dust PSD, while similar to that of the input dust, exhibits sharper peaks and higher frequencies. The mean particle size and standard deviation decreased by 2 %-17 %, indicating finer and more concentrated deposition. The sorting coefficient consistently exceeded 4.0, reflecting poor sorting and a wide size range, while skewness values (0.2-0.3) confirmed a positive skew toward finer particles. Kurtosis remained near 0.98, suggesting a distribution shape similar to the original dust. Numerically, these PSD shifts can increase PV glass transmittance by 7 %-22 %, thereby indirectly improving power output. These findings highlight the importance of incorporating spatial dust heterogeneity and granulometric parameters into PV array design and energy forecasting, especially in arid regions. Optimizing array layout can help regulate deposition patterns and enhance overall power generation efficiency. Further field studies under realistic conditions are recommended to validate these results.