Study of Dust Particles on Solar Mirrors for Measurement of Soiling by Specular Reflectance and Imaging Assessment




Solar Mirrors, Reflectance, Soiling


During the life time of Concentrated Solar Power plants (CSP), optical performances of solar mirrors are affected by soiling phenomena and surface degradations. In order to provide an adequate cleaning strategy, operators must determine the performance loss induced by soiling. Several commercial instruments already exist to measure optical reflectance, but they are dedicated to a single wavelength range or angle, contact and punctual measurements or to laboratory analyses. CEA has developed a new kind of sensor to measure separately the loss of specular reflectance thanks to a CCD camera and photodiodes. In this study, we compared the cleanliness factor calculated with the specular reflectance measured by commercial devices with the image processing performed with our equipment on different artificially soiled solar mirrors. The aim is to ensure that different levels of dirt on the mirrors can be easily assessed with a camera and image processing. We conclude that the level of soiling and the calculation of the percentage of dirty surface are similar to the measurement of the absolute reflectance for all the mirrors tested. These combinations of non-contact, automated, fast and precise measurement with image processing are reproducible for all levels of soiling.


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IRENA, The power to change: Solar and wind cost reduction potential to 2025, tech. rep., International Renewable Energy Agency (IRENA), 2016.

R. Conceicao, H.G. Silva, M. Collares-Pereira, CSP mirror soiling characterization and modeling, Solar Energy Materials Solar Cells, 185 (2018) 233-239, doi:

SolarPACES Reflectance Guideline, Version 3.1. April 2020.

R. Conceicao, J. Gonzalez-Aguilar, A. Alami Merrouni, M. Romero, Soiling effect in solar energy conversion systems: A review, Renewable and Sustainable Energy Reviews 162 (2022) doi:

F. Sutter and al., “Advanced Measurement Techniques to Characterize the Near-Specular Reflectance of Solar Mirrors”, SolarPACES Conference 2018, doi:

E. Le Baron, A. Grosjean, D. Bourdon, A-C. Pescheux, F. Vidal, A. Disdier, New Equipment for Measurement of Soiling and Specular Reflectance on Solar Mirrors, , in 'Solar PACES 2019', doi:

Patent EN 17 61041 O. Raccurt, C. Delord, P. Giraud, A-C. Pescheux, Système de surveillance de la dégradation et de l'encrassement d'un miroir, CEA.

Devices and Services Company, Devices and Services Portable Reflectometer Model 15R- USB.

MT Solutions BV, ARTA – Technical Description, 2010.

G. Bern, T. Schmidt, N. Celentano, A. Heimsath, P. Nitz, FREDA - An Automated Field Reflectance and Degradation Assessment System for Central Receiver Systems, in AIP Conference Proceedings, Vol. 2033(AIP Publishing, 2018), doi:

F.Wolfertstetter, R. Fonk, C. Prahl,; M. Röger, S. Wilbert; J. Fernández-Reche, Airborne soiling measurements of entire solar fields with Qfly. AIP Conf. Proc. 2020, doi:

M. Gostein, B. Bourne, F. Farina and B. Stueve, "Field Testing of Mars™ Soiling Sensor," 2020 47th IEEE Photovoltaic Specialists Conference (PVSC), Calgary, AB, Canada, 2020, pp. 0524-0527, doi:

G. Zhu, D. Kearney, M. Mehos, “On characterization and measurement of average solar field mirror reflectance in utility-scale concentrating solar power plants”, Solar Energy Vol 99, pp. 185-202, 2014, doi :

Harald Galda, “Image processing with Scilab and Image processing Design Toolbox Copyright”, 2011.




How to Cite

Le Baron, E., Grosjean, A., & Disdier, A. (2024). Study of Dust Particles on Solar Mirrors for Measurement of Soiling by Specular Reflectance and Imaging Assessment. SolarPACES Conference Proceedings, 1.

Conference Proceedings Volume


Measurement Systems, Devices, and Procedures

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