Heliostat Soiling Rate Study under Realistic Tracking Conditions

Abstract

The soiling of solar mirrors for Concentrating Solar Thermal (CST) Technologies, due to its relation with reduced optical yield of the systems and the considerable need of cleaning efforts for O&M, is a topic of interest in the community since the beginning of the development of these technologies in the 1970’s. Especially in recent years, research activities have significantly increased, covering a wide range of aspects from dependence on meteorology, over prediction, influence on yield to measurement systems and techniques. Apart from climatic conditions and presence of airborne particles, as all reflectors have to be constantly repositioned throughout the day and the year to reflect and focus the incoming solar radiation onto a target, the reflector’s movement and position can also play a role in the way the reflectors are soiled. In this work, a campaign was developed to investigate the influence of the tracking of heliostats on the soiling behavior, focusing on parameters such as realistic tracking, movement time, stow positions, seasonal changes and height influence.