Parabolic trough solar power plants produce the lowest cost solar electricity, yet unsubsidized electricity from parabolic trough power plants costs about twice that from conventional sources. To make parabolic trough electricity more competitive, we are developing an innovative approach for rapidly and effectively evaluating the alignment of mirrors in parabolic trough power plants and prescribing corrective actions as needed. The Theoretical Overlay Photographic Collector Alignment Technique (TOPCAT) system could be used during construction, to improve the performance of existing power plants, or for routine maintenance. It is also an enabling technology for higher concentration ratio and lower cost trough solar collector designs needed to make solar electricity more competitive with conventional sources. In this paper a truck-mounted TOPCAT field characterization system is described. Test results from mirror alignment of an LS-3 loop in a commercial parabolic trough power plant in southern California are also presented. The performance improvements were measured using a comparative calorimetric technique which inherently accounts for variations in insolation levels, sun incident angle, and mirror and heat collection element (HCE) glass envelope cleanliness. Measurements indicate a 3.5% increase in thermal performance of an LS-3 loop aligned with the TOPCAT system. Benchmarking results of labor hours and materials show that the TOPCAT system is an extremely cost effective tool for improving the performance of existing parabolic trough power plants.

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