Multi-physics investigation of concentrating efficiency degradation in heliostats caused by wind-induced deformations

Heliostats, typically deployed in open and wind-prone regions, possess a large reflective surface area supported by lightweight, flexible structures, making them highly susceptible to wind loads. Wind-induced deformations can significantly compromise the precision required for accurate solar tracking and concentrating efficiency of heliostats. This study introduces a numerical multi-physics methodology that couples computational fluid dynamics (CFD), finite element modeling (FEM), and ray-tracing optical simulations to investigate the effects of heliostat postures and wind direction angles on concentrating efficiency across four solar terms: spring equinox, summer solstice, autumn equinox, and winter solstice. Based on solar tracking principles and site-specific meteorological data for wind direction and speed, variations in heliostat concentrating efficiency are evaluated under both calm and windy conditions. The direct normal irradiance (DNI) is integrated over time, and the cumulative solar energy per unit mirror area is compared for a representative day at each solar term. The results reveal that wind-induced deformations reduce concentrating efficiency by 10.35 %–24.44 %, particularly in the peripheral regions of the mirror panel, corresponding to an average reduction of approximately 17.23 % in thermal energy capture. Moreover, as the wind direction angle increases, the efficiency loss tends to decrease. Among the four solar terms, the winter solstice exhibits the highest efficiency loss and the greatest fluctuation in concentrating efficiency. The findings of this study provide a numerical basis for structural optimization and the enhancement of optical performance in heliostats under complex wind conditions.