Comparative analysis of energy produced by photovoltaic modules with anti-soiling coated surface in arid climates

Dust accumulation on the surface of photovoltaic modules decreases the transmittance and produces power losses and consequently daily energy losses. These losses are important in large photovoltaic power plants, mainly in arid areas. The company Asahi Kasei Corporation has developed a new self-cleaning coating for photovoltaic applications. The performance of photovoltaic modules can be increased due to the two main properties of the coating film: anti-reflectiveness and self-cleaning effect. The aim of this work is the comparative evaluation of the energy produced by photovoltaic modules with and without anti-soiling coating. For this purpose, six photovoltaic modules of the same manufacturer and technology, three with coated surface and three without it, have been tested under outdoor conditions for a year in the laboratory of photovoltaic systems at the University of Málaga, southern Spain. Our results show that dust accumulation on the surface of the module reduces the performance in terms of energy and power, due to a decrease of the transmittance. Furthermore, the non-homogeneity of the distribution of dust on the surface of the module causes additional power losses. Obtained outcomes show that in dry periods (without rainfall) energy soiling losses are much higher. In these cases the energy losses for both kinds of photovoltaic modules reach significant values, but daily energy soiling losses are greater for modules without self-cleaning coating. Modules with coating film have an average daily energy soiling losses of 2.5% whereas for the uncoated modules this value is 3.3%.