Self-cleaning coatings for minimizing the impact of dust precipitation on the power production of solar cells utilizing mesoporous TiO2/SiO2 and ZnO/SiO2 films

Abstract

The production of customized site-specific anti-soiling nanocoatings is needed for better utilization in dry parts of the world, with consideration of natural dust fallout in those regions. Kuwait's atmosphere carries airborne dust 70% of the year. Thus, designing anti-soiling nanocoatings for the arid region is necessary when dusty atmospheres are considered the norm. In this contribution, all solar cells were coated by SiO2, ZnO/SiO2, and TiO2/SiO2 films for self-cleaning applications and were tested in the summer period with the high level of dust and temperatures the current, voltage and power output was measured. We directly relate the coatings' performance to the electrical power output of the coated solar cells, which is considered among the few studies in this field. Influences of properties ZnO/SiO2 and TiO2/SiO2 films, such as the surface morphology, transparency, and water contact angles on the power production efficiency of solar cells, were systematically investigated. The three fabricated films showed a contact angle of about 70o agrees with the expected hydrophilicity behaviour. The thickness values of SiO2, TiO2/SiO2 and ZnO/SiO2 films were found to be ∼35, 205 and 240, respectively. Transmission values of the synthesized SiO2, TiO2/SiO2 and ZnO/SiO2 films were determined at about 97.95, 96.62 and 96.25%, respectively, suggesting that all synthesized films are highly transparent over the visible range. Solar cell samples were subjected to natural conditions for 30 days in the summer. The results indicated that the effect of dust on the power production efficiency for ZnO/SiO2 and TiO2/SiO2 coated PV cells was lower than the solar cells coated with SiO2 film concluded from the low power output of 0.16 Watt for this coating compared to 0.18 and 0.2 Watts for the other two coatings. The mesoporous ZnO/SiO2 and TiO2/SiO2 films not only significantly minimized the accumulation of dust on the PV cells but also boosted the power-generating efficiency. The average daily power output of around 0.2 Watt and the deviation values of the soiling ratios of about 5% showed that TiO2/SiO2 film was a durable coating against dust for the presented experiment time, while the ZnO/SiO2 film started as good, but showed deterioration after six days of the experiment with a deviation in SR value reached 15%. The TiO2/SiO2 nanocoating showed consistent behaviour with lower deviations for soiling ratio (SR) values and constant average power output for the solar cells concluding good durability in solar cells tests during harsh conditions in the summer, implying the excellent service life of solar cells.