A nanodiamond coating for use on a solar cell, the coating including a nanodiamond material suspended in a liquid, wherein the nanodiamond material has a size range from about 1 nm to about 10 nm. Methods for improving the efficiency of a solar cell are provided, including, mixing a nanodiamond material with a liquid polymer or non-polymer solvent to form a nanodiamond-polymer suspension, forming a coating of the suspension on a top surface of a solar cell, and drying the coating such that a dried nanodiamond-polymer layer remains bonded to the solar cell. Useful nanodiamond coating compositions may include a nanodiamond material, a fluoropolymer, a liquid solvent for the fluoro-polymer and at least one additive selected from the group consisting of dispersing agents, adhesion promoters, and coupling agents. The fluoropolymer may also be used in the form of an aqueous dispersion.