Analysis of soiling measurement devices for solar technologies

Soiling of solar systems is a significant issue that negatively impacts the performance of both concentrating solar thermal (CST) and photovoltaic (PV) systems installed both in generation plants and in industries and buildings leading to increased operation and maintenance costs. This phenomenon is particularly relevant in areas with high concentrations of dust and other airborne pollutants, such as arid and semi-arid environments. In this work, a comparison is made between several soiling sensors based on different measurement principles such as PV reference and optical. The sensors were exposed for two months in a semi-arid environment at the Plataforma Solar de Almería (PSA), Spain. Results show that sensors using the optical soiling measurement are less sensitive to soiling detection than sensors using PV reference. A comparison with measurements of hemispherical transmittance for a solar and PV glass and specular reflectance for a solar mirror with the sensors is carried out. It allows to detect that the weekly soiling rate in the mirror is at least four times higher than the soiling rate of the most sensitive sensor. The results of this comparison allow for more reliable integration of this important measure into solar installations monitoring systems.