Camera Based Reflector Degradation Detection

Abstract

Reflectors used in the solar fields of concentrated solar thermal technologies must maintain excellent optical properties over the lifetime of the commercial projects. However, the reflec-tor materials are prone to degradation due to environmental stresses. Measurements with portable reflectometers are the state-of-the-art technique to evaluate degradation in the field, determining the most significant optical parameter, the reflectance. Some degradation mech-anisms can evolve on reflectors in early stages without compromising reflectance, until they affect a large surface. This is why alternative measurement techniques are necessary. In this work, the development of an easy-to-use field measurement procedure for the degradation of solar reflectors is presented, which was investigated at the OPAC laboratory of the CIEMAT-Plataforma Solar de Almería (PSA). An automated image processing program has been de-veloped, to determine the degraded area of reflectors based on various image sources. The capabilities to measure different scales of defect sizes on different reflector materials, with simple commercial camera equipment and a portable microscope, were analyzed, and future development steps are presented.