Wind-driven hail threats to heliostats: Dynamic modeling and stow strategy optimization for CSP plants

Heliostats in concentrated solar power plants frequently encounter extreme weather conditions, particularly in solar-rich regions where strong winds often accompany hailstorms. Although these combined phenomena threaten structural integrity, the wind-driven effects on hail trajectories remain poorly quantified, making optimal stow strategies difficult to determine. To address this challenge, a comprehensive dynamic model is developed that systematically accounts for wind-hail interactions. The model first establishes analytical formulations describing hailstone kinematics under wind influence, with specific examination of how varying wind speeds alter horizontal displacement, velocity components, and descent angles. Subsequently, heliostat safety performance is evaluated across different environmental conditions. Importantly, horizontal wind effects are demonstrated to generate non-negligible hailstone motion compared to vertical descent, with smaller hailstones exhibiting greater susceptibility to wind disturbances. Furthermore, stress analysis reveals a characteristic shift from compressive to tensile stress distributions during impact events as wind speeds increase. Through extensive parametric studies, clear relationships between wind conditions and hail impact characteristics are established. These findings directly inform protective measures, particularly regarding optimal stow angle determination under varying threat levels. For implementation, practical guidelines are provided to enhance heliostat resilience against compound wind-hail threats, ultimately supporting more reliable renewable energy generation in vulnerable regions.