Method for producing coating solution for use in solar collector modules and coating composition produced by the same

A method for producing a coating solution for glass of a solar collector module to enhance optical transmittance, comprising:

• adding a coagulation-inducing agent containing a silica sol and/or an alumina sol to a solution containing aluminum alkoxide to induce a sol-gel reaction, thereby preparing a sol comprising particles of about ten nanometers to about five hundred nanometers (nm) in diameter,
• adding a stabilizing agent to the sol to stabilize the particles in the solution,
• subjecting the sol to a sol-gel reaction with an aluminum alkoxide after adding the stabilizing agent,
• mixing about 100 parts by weight of the silica sol with about 10 to about 40 parts by weight of the alumina sol when both silica sol and alumina sol comprise the coagulation-inducing agent, and
• adding an acidic catalyst to lower the pH into an acidic range when the coagulation-inducing agent is basic,
• wherein the coagulation-inducing agent reacts with aluminum alkoxide and comprises at least one selected from the group consisting of a silica sol and an alumina sol, and
• wherein the sol-gel reaction is performed at a temperature of about 50° C. to about 80° C.