In the arid northwest of China, dust accumulation causes photovoltaic (PV) module efficiency losses, necessitating hydrophobic coatings with high transparency, self-cleaning ability, mechanical durability, and weather resistance. A series of coatings with distinct nanoscale surface roughness profiles were fabricated via sol-gel and dip-coating processes. These coatings were constructed by forming an organic-inorganic network through the cross-linking of hydroxyl-terminated poly(dimethylsiloxane) (PDMS-OH) with tetraethyl orthosilicate (TEOS), followed by synergistic modification with trimethylethoxysilane (TMES) and gamma-methacryloxypropyltrimethoxysilane (KH570). By increasing the PDMS-OH content, the size of SiO2 nanoparticles within the coating was progressively reduced from 200 to 300 nm to below 100 nm, ultimately forming a nanostructured composite with tunable surface roughness. The optimal coating exhibited a water contact angle (WCA) of 135 degrees and a maximum transmittance of 97.7% at 680 nm. Excellent weatherability was demonstrated through a series of tests. When applied to PV modules, this coating immediately improved the photoelectric conversion efficiency (PCE) by 3.91%. More importantly, after 30 days of outdoor exposure, coated samples cumulatively reduced dust deposition by 28.31% and boosted the conversion efficiency to 10.74%, with the PCE enhancement being further amplified. This work provides a straightforward and fluorine-free nanostructured self-cleaning coating solution, which is of practical significance for extending the operational lifespan and enhancing the power generation efficiency of PV systems in arid regions.