THE DEVELOPMENT OF STRETCHED-MEMBRANE HELIOSTATS IN THE UNITED-STATES

For more than 10 years, the US Department of Energy's Solar Thermal Program has pioneered the development of heliostats, mirrors that track the sun, for solar central-receiver power plants. The field of heliostats is the single most expensive part of such plants, so their cost must be as low as possible for the technology to be commercially successful. In the last six years, Sandia National Laboratories has been developing and transferring to private industry a technology that uses stretched-membrane reflectors in place of the more familiar glass mirrors. Because of their simplicity and lighter weight, stretched-membrane heliostats have the potential to cost significantly less than current glass-mirror designs. Two generations of 50 m2 prototype stretched-membrane mirror modules were evaluated at Sandia's National Solar Thermal Test Facility in Albuquerque, NM. They demonstrated an optical performance rivaling that of the more familiar glass-mirror heliostats. Sandia recently initiated the final phase of development: the design of fully integrated, market-ready heliostats. Field tests are planned for late 1990.