Polymeric Glazings

Polymer-glazed mirrors may provide lower-cost alternatives to current glass mirror designs. The glass mirror fields account for about half of the cost of a central receiver power system, and it is estimated that central receiver system costs need to be halved to be economically viable. Polymer-coated aluminum mirrors have been used in field tests that indicate life spans of at least several years. The (solar-weighted) reflectance of aluminum mirrors is limited to about 85% by the aluminum, while polymer-coated silver mirrors can have reflectances of 96%. System studies suggest that the difference in reflectances can have an important cost impact that probably will exclude the use of aluminum. Polymer-protected silver mirrors that can withstand outdoor use with sufficient lifespans arenot yet developed. This study was undertaken to evaluate polymer-coated silver mirrors with reflectances greater than 90% that can approach a lifespan of five years.