Soiling Forecasting for Parabolic Trough Collector Mirrors: Model Validation and Sensitivity Analysis

Atmosphere, vol. 16, pp. 807

Abstract

Parabolic trough collector (PTC) systems, often deployed in arid regions, are vulnerable to dust accumulation (soiling), which reduces mirror reflectivity and energy output. This study presents a physically based soiling forecast algorithm (SFA) designed to estimate soiling levels. The model was calibrated and validated using three meteorological data sources—numerical forecasts (YR), METAR observations, and on-site measurements—from a PTC facility in Limassol, Cyprus. Field campaigns covered dry, rainy, and red-rain conditions. The model demonstrated robust performance, particularly under dry summer conditions, with normalized root mean square errors (NRMSE) below 1%. Sedimentation emerged as the dominant soiling mechanism, while the contributions of impaction and Brownian motion varied according to site-specific environmental conditions. Under dry deposition conditions, the reflectivity change rate during spring and autumn was approximately twice that of summer, indicating a need for more frequent cleaning during transitional seasons. A red-rain event resulted in a pronounced drop in reflectivity, showcasing the model’s ability to capture abrupt soiling dynamics associated with extreme weather episodes. The proposed SFA offers a practical, adaptable tool for reducing soiling-related losses and supporting seasonally adjusted maintenance strategies for solar thermal systems.

Authors 7

1. Areti Pappa

   University of Patras

   Affiliation as printed

   Laboratory of Atmospheric Physics, University of Patras, 26504 Patras, Greece

2. Johannes Christoph Sattler Aachen

   FH Aachen

   Affiliation as printed

   Solar-Institut Jülich (SIJ) of the FH Aachen University of Applied Sciences, Heinrich-Mussmann-Str. 5, 52428 Jülich, Germany

3. Siddharth Dutta
   Affiliation as printed

   Protarget AG, Zeissstrasse 5, 50859 Cologne, Germany

4. Panayiotis K. Ktistis

   Cyprus University of Technology

   Affiliation as printed

   Department of Mechanical Engineering and Materials Science and Engineering, Cyprus University of Technology, 3036 Limassol, Cyprus

5. Soteris A. Kalogirou

   Cyprus University of Technology

   Affiliation as printed

   Department of Mechanical Engineering and Materials Science and Engineering, Cyprus University of Technology, 3036 Limassol, Cyprus

6. Orestis Spiros Alexopoulos Aachen

   FH Aachen

   Affiliation as printed

   Solar-Institut Jülich (SIJ) of the FH Aachen University of Applied Sciences, Heinrich-Mussmann-Str. 5, 52428 Jülich, Germany

7. Ioannis Kioutsioukis corresponding

   University of Patras

   Affiliation as printed

   Laboratory of Atmospheric Physics, University of Patras, 26504 Patras, Greece