Measurement and assessment of parabolic trough mirror soiling in an operational CSP plant in southeastern United States.

摘要

Soiling of solar collector mirrors in concentrating solar power (CSP) applications is a major factor influencing component and system reliability, thermal efficiency degradation, and minimization of maintenance costs. Research is needed to identify mechanisms to minimize soiling or dust accumulation effects in different geographic and climatic regions as deposition on mirrors is location-specific and modulated by several factors, including soil parent material, microclimate, and frequency and intensity of dust events. With over 300 publications generated in the last five years alone, the effects of soiling and particle accumulation on solar power is a high interest topic. The UL Lafayette Solar Technology Applied Research and Testing (START) lab consists of a large aperture parabolic trough CSP facility in operation since 2013 where spectrometry measurements are taken regularly as part of plant operation and evaluation of the degree of soiling that the reflective surfaces have undergone. Based on operational outcomes, recommendations regarding cleaning procedure and frequency have been developed and are reported. Several models and generations of reflector composition have been evaluated, covering three generations of thin-film polymer chemistry and including several assembly methods. A low-cost gloss meter is used for spectrometry measurements for detecting reductions in specularity which are correlated to the actual plant energy production. This study analyzed solar collector soiling data for three different thin film types: 3M 1100, 3M 2020, and Konica Minolta film mirror. The data, along with parabolic trough cleaning costs and energy pricing considerations, was used to determine the optimal days between cleaning. Analysis of the results reveals that the 3M 2020 film has the fastest soiling degradation rate, and that the mirrors washing rate should be increased from its current standard to optimize cost savings.