Solar cell degradation control-coating liquid and thin film and solar cell degradation control method

A solar cell degradation control-cover glass having a solar cell degradation control-thin film formed by applying to a back surface of said cover glass a solar cell degradation control-coating liquid comprising:

• an aqueous solution of a water-soluble compound of at least one metal selected from silicon, aluminum, zirconium, tin and zinc;
• or
• a fine particle dispersion liquid of an oxide of said metal, wherein said aqueous solution and said fine particle dispersion liquid each contain said compound or said oxide in an amount of 0.01 to 10% by mass in terms of metal oxide, and said fine particle dispersion liquid contains fine particles that have an average primary particle diameter of not larger than 50 nm and are dispersed at a dispersion particle diameter (D50) of smaller than 100 nm.