Abstract: Functional coatings, Anti-Reflection (AR), self-cleaning and anti-fogging have been applied to cover glass of crystalline silicon photovoltaic cells to increase the efficiency of photo-electric conversion. In this study, hydrophobic AR coatings with various sized silica Nanoparticles (NPs) were fabricated on slide glass substrate by sol-gel process and spin-coating process. The surface shape of the AR coating films was investigated by a field emission scanning electron microscope and scanning probe microscope. The measurement of contact angle was performed to confirm the hydrophobicity. The transmittance of the AR coating layers was estimated by an UV-visible spectrometer. The results showed that the AR coating layers of 30, 100 and 150 nm silica NPs exhibit hydrophobic characteristic with contact angle of over 115°. The average transmittance of 7 nm silica NPs coating thin layer exhibits 3.3% higher than one of the bare slide glass substrate per single side coating in the visible light range. The most effective AR coating layer is 7 nm silica NPs coating while AR coating layer of 100 nm silica NPs coating exhibits most hydrophobic characteristic of 123.4°. The optimum functional coating, anti-reflective and hydrophobic coating surface was 30 nm silica NPs coating layer with the average transmittance of 91.2% and contact angle of 116°. The hydrophobic AR coating with 30 nm silica nanoparticles is capable of application for cover glass of photovoltaic cells.