Soiling Loss Quantification of Roof-Top Mounted Solar Module in Mombasa Using Digital Imagery Techniques

Abstract

Photovoltaic cells' output performance is negatively impacted by the particles that are deposited on the solar panels which scatter and absorb solar energy. The particles cause shading on the PV modules and when they are densely sparse on the PV panel and depending on their light transmittance, could adversely reduce the intensity the amount of irradiance reaching the PV cells. This study quantified soiling loss of rooftop solar photovoltaic using images of soiled PV panels in Mombasa County, Kenya. This study estimated a significant intensity of soiling of rooftop mounted modules in Mombasa.  A pilot study was conducted on the roof-top of s Laboratory at Technical University of Mombasa for 90 days using two fixed angle and azimuth modules; One of them was cleaned everyday while the other was left soiled for the entire period. In the setup, high resolution pictures were taken daily for 90 days for dust pixel analysis. The analysis of the pixels revealed that soiling reduced pixel intensity on the panel by 10 per cent. Clean panel had an average pixel intensity of 132.47 in the first day. After 30, 60 and 90 days, the pixel intensity of soiled panels were 148.96, 151.96 and 148.42, respectively. It was observed that the particles that collected on the surface of the PV module reduced optical characteristics of the panel for the first two months before the onset of rain in the third month. The highest loss of 19.34 was witnessed in the second month.