A comparative study of N-Phase shifting algorithms and their application on optical quality control of solar concentrators

摘要

Solar thermal systems are the most promising renewable energy source to cover the big electrical demand of the society and the industrial sector. The optical errors of solar collectors, which represents a considerable part of the total investment of a solar plant, has a direct impact on the optical and thermal efficiencies. For that sake, it is important to evaluate their optical quality before installation and during operation. This analytical study provides a comparative and comprehensive overview of the N-Phase Shifting algorithms used to calculate slope errors in solar mirrors. As a matter of elaboration, these algorithms constitute the main core of the Fringe Reflection Technique or otherwise called the Deflectometry technique. The accuracy of this technique strongly depends on the precision and insensitivity of the N-phase shifting algorithm used. The main objective of this work is to compare the N-phase shifting algorithms according to their accuracy, rapidity, sensitivity to the phase errors, and to the total time consumed to qualify a single solar mirror. As a final phase, the appropriate algorithm that meets our needs is selected and used to evaluate the optical quality of a solar collector installed in the Green Energy Park research platform, Morocco.