Computation of canting errors in heliostats by flux map fitting: experimental assessment

Abstract

In solar tower plants, thousands of heliostats reflect sunlight into a central receiver. Heliostats consist of a subset of mirrors called facets that must be perfectly oriented (i.e., canted) to concentrate as much solar radiation as possible. This study presents and validates the so-called flux map fitting technique to detect and correct canting errors. The computed distributions were matched to a series of images through an optimization algorithm. According to the sensitivity analysis, three images spread along a single day provide sufficient information for the algorithm to succeed. Using this methodology, four heliostats at the THEMIS research facility were recanted, thereby substantially increasing the optical quality in three of them. The procedure to infer the heliostat aimpoint was assessed.Universidad Carlos III de Madrid (2020/00051); European Commission (823802); Horizon 2020 Framework Programme (727762). We thank the CNRS-PROMES laboratory, UPR 8521, belonging to the French National Center for Scientific Research (CNRS), for providing access to its facilities, the support of its scientific and technical staff, and the financial support of the SFERA-III project (Grant Agreement No. 823802). We thank the technical help provided by Yann Volut, William Baltus, and Antoine Pérez. The research project VISHELIO-CM-UC3M has been funded by the call "Programa de apoyo a la realización de proyectos interdisciplinares de I+D para jóvenes investigadores de la Universidad Carlos III de Madrid 2019-2020" under the framework of the "Convenio Plurianual Comunidad de Madrid-Universidad Carlos III de Madrid". This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 727762, project acronym NEXT-CSP.Publicad