Ordered Mesoporous Slippery Silica Coatings on Photovoltaic Cover Glasses to Enhance Photocurrent with Sustainability for Large-Scale Applications

The performance of photovoltaic solar modules deteriorates quickly under ambient conditions due to the accumulation of dirt and biofouling on the surface of cover glasses. We have designed robust ordered mesoporous silica-based slippery (OMSS) coatings on photovoltaic cover glasses (PVCGs) with a quasi-random ripple-like top surface morphology to further decrease solar light reflection and ease cleaning for long-term use. OMSS coatings on such PVCGs showed year-round climatic sustainability and a significant increase in the photocurrent of the modules with excellent durability, confirmed by long-term outdoor use and ASTM testing. The average top surface reflection and overall transmission of the OMSS-coated PVCG decreased and increased to 3.5% and 4%, respectively, in the wavelength region of 380–2000 nm. Accordingly, the photocurrent increased by about 4.1% under 1 sun (100 mW cm–2) conditions. The water-repellent slippery nature of the OMSS coating was confirmed by its high water contact angle (123 ± 3°) and low hysteresis (10 ± 2°) values. Outdoor testing of a series of OMSS-coated PV modules with dimensions of 640 × 640 mm2, each fabricated with 36 Si-solar cells, showed an increase of ∼6.7–10.5% power compared to the modules without coatings. The improved performance under ambient conditions is due to the combined effect of the antireflection and anti-dirt properties of the OMSS coatings. The PV modules installed on the rooftop of CSIR-CCGRI were monitored for ∼3 years with a cleaning schedule of once a month by water-flushing and were found to perform without any deterioration of power due to the robust and durable structural design of the OMSS coating.