On characterization and measurement of average solar field mirror reflectance in utility-scale concentrating solar power plants

• Published in: Solar energy Vol. 99; pp. 185 - 202
• Main Authors: Zhu, Guangdong, Kearney, David, Mehos, Mark
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.01.2014; Elsevier; Pergamon Press Inc
• Subjects: Applied sciences; Concentrating solar power; Electric fields; Electric power generation; Electric power plants; Electrical engineering. Electrical power engineering; Electrical power engineering; Energy; Exact sciences and technology; Mathematical models; Measurement techniques; Measurement uncertainties; Natural energy; Non classical power plants; Panels; Parabolic trough; Photovoltaic power plants; Power plants; Reflectance; Reflectivity; Solar collectors; Solar energy; Solar power generation; Solar thermal conversion; Solar thermal power plants; Specular reflectance; State of the art; Specular reflectance; Measurement uncertainties; Concentrating solar power; Parabolic trough; Performance evaluation; State of the art; Solar collector; Acceptance test; Scheduling; Baseline; Commercial plant; Solar tower; Implementation; Accuracy; Solar power plant; Measurement uncertainty; Solar energy; Measurement method; Mirror; Reflectance
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2013.11.009

•Developed a reliable and generalized mathematical model of mirror specular reflectance.•Suggested a feasible procedure of measurements on average reflectance in a utility-scale solar field.•Illustrated the practical measurements at a 80MWe parabolic trough plant. Due to the emerging need for the development of acceptance test codes for commercial concentrating solar power (CSP) plants, an effort is made here to develop a mirror reflectance model suitable for CSP applications as well as a general procedure to measure the average mirror reflectance of a solar field. Typically, a utility-scale solar field includes hundreds of thousands of mirror panels (if not more), and their reflectance is subject to many factors, such as weather and planned washing schedule. The newly developed mirror reflectance model can be used to characterize different types of mirror materials and can be directly used to perform optical performance evaluation of solar collectors. The newly proposed procedure for average solar field reflectance measurements includes a baseline comprehensive measurement and an individual factor measurement: the former allows a comprehensive survey of mirror reflectance across the whole solar field, and the latter can provide correcting factors for selected individual factors to further improve the accuracy of the baseline measurements. A detailed test case implementing the general procedure is applied to a state-of-the-art commercial parabolic trough plant and validates the proposed mirror reflectance model and average reflectance measurement procedure. In the test case, the plant-wide reflectance measurements at a commercial utility-scale solar plant were conducted and can shed light on relevant analysis of CSP applications. The work can also be naturally applied to other types of solar plants, such as power towers and linear Fresnel plants.