Degradation analysis of photovoltaic modules with solar cells manufactured with SiO2 + TiO2 thin films

This paper presents an evaluation of monocrystalline silicon photovoltaic (PV) modules after 8.3 years of operation at an electric vehicle station in southern Brazil. Silicon solar cells were produced using Al-BSF technology with TiO2+SiO2 antireflection and passivation layers. Visual inspection revealed that milky patterns were the most frequent defects, appearing in 84 % of the 1080 solar cells, mostly at the edges of each device. Image processing allowed us to obtain the milky pattern area of all the cells, and a correlation was observed between the extent of these defects and the degradation of the maximum power and short-circuit current. No cleaning was performed during the exposure period, and the accumulation of dust and cementation resulted in stains on the lower edge of the modules installed in the landscape orientation. These defects caused a relatively low power degradation of 1.8 % after 8.3 years of exposure, with an average annual degradation rate of approximately 0.2 %, which was lower than that reported in the literature for solar cells with SiNx or TiOx thin films.