Inhibiting degradation of wet process manufactured solar mirrors

Abstract

The impact of heliostat mirror degradation on the performance of central receiver power plants can be significant. Presented in this paper is a probable cause of mirror degradation and a possible method of inhibiting this degradation without encapsulating the mirror. One possible cause of mirror degradation is the dissolution of the soda-lime-silicate surface at the silver-glass interface. The initiation of this degradation may begin at the time of production and continue as a result of glass-water interaction. Inhibiting this dissolution may be possible by treating the glass surface with trivalent lanthanide ions prior to the silvering deposition. The lanthanide ions can be incorporated into the production line without additional capital investment and without interfering with the efficiency of the silvering reaction. Leaching experiments have been performed as a form of accelerated weatherization on mirrors and on soda-lime-silicate glasses. The glasses and mirrors doped with a series of different lanthanide ions show that significant gains may be realized towards preserving the integrity of the glass surface.