Photovoltaic solar cells white Spot Phenomenon in high humidity Coastal: Environmental Factors and Performance Implications

Abstract

This paper presets a "cell spotting" phenomenon that was noticed on the rooftop PV systems along the coast in Tartous, Syria, during the summer, mainly in the early morning and late evening hours under specific environmental conditions. This phenomenon appeared as white spots on the photovoltaic cells. Repeated periodic measurements were taken over four months during the summer, revealing a strong correlation between the appearance of these spots and high humidity levels (above 50%), high temperatures, low direct solar radiation, and dust accumulation. Infrared images were taken of the studied panels during the study period in order to show the temperature deference between the cells with white spots and the other cells in the same panel, and the deference was about 2°C. After cleaning the cleaning the panels, the phenomenon was disappeared. Also, when the sunlight is not direct on the PV panel surface, the phenomenon does not appear. Practical measurements of temperature, humidity, and solar radiation monitoring revealed a strong correlation between the presence of this phenomenon and high humidity, temperature, dust accumulation, and indirect solar radiation on the surface of the panels. It was concluded that this phenomenon is a transient effect caused by a dust and moisture interaction, a condensation related process and appears as a white layer on the outer surface of the panel above the effected cells.