A Novel Method for Automatic Real-Time Monitoring of Mirror Soiling Rates

Abstract

The effect of soiling of solar concentrators influences the output of solar thermal power plants significantly. The literature values estimate the loss in specular reflectivity due to dust on the mirrors to be as high as 14% or even 26% after a few months. It varies significantly with location. Given the fact that these numbers are quite high and very broadly spread in the literature, project planners and plant operators demand better methods to measure soiling loads in running power plants as well as in resource assessment measurement campaigns. In this paper we introduce a new measurement setup named “TraCS” (Tracking Cleanliness Sensor) that allows for an easier, supposedly more precise and more cost effective measurement of the soiling level of solar mirrors. It will assist power plant operators and maintenance teams to optimize their cleaning cycles based on a real time measurement. At the same time the setup paves the way to including cleanliness as a standard parameter in solar resource assessment. It enables more sophisticated research on the most important weather parameters influencing the soiling rates at different plant sites and on upcoming new coating materials.