NREL Researchers Test Solar Thermal Technology

For more information contact:
e:mail: Public Affairs

Golden, Colo., September 23, 1997 -- A prototype heliostat which could take solar technology a step into the future is being tested at the U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL). It was developed by Science Applications International Corporations (SAIC) Golden office.

The heliostat is a large tracking mirror for use in solar thermal power plants. SAIC's prototype heliostat incorporates a number of design and manufacturing modifications that could lead to significant cost reductions. The major modifications include a larger reflective area (170 square meters) and a low-cost mirror facet design in which thin-glass mirror tiles are adhered to a stainless steel stretched-membrane to provide a reflective surface. A prototype production line for manufacture of heliostats has been developed and installed under this program.

SAIC's low cost stretched-membrane heliostat represents a significant advancement in making power tower systems cost-competitive with conventional power sources. The heliostat was developed by SAIC under SunLab's Solar Manufacturing Technology (SolMaT) initiative. SunLab is a DOE research organization, which combines the expertise of NREL and Sandia National Laboratories, the nations two leading resources for solar thermal research.

"This heliostat is the largest heliostat in DOE's Solar Thermal Electric Program today. The SolMaT Program together with SAIC's capital investment have provided the capacity to build 70 heliostats a year capable of producing 2.1 megawatts of electric power," said Dr. Barry L. Butler, vice president and manager of SAIC's Solar Energy Products Division.

"Installation of this heliostat is a major milestone in achieving cost-effective volume manufacturing of heliostats which are the largest cost component of power tower systems," said Kelly Beninga, assistant vice president and manager of the Golden office.

Power towers, a type of solar thermal power plant, include a field of heliostats that focus sunlight onto a tower-mounted central receiver filled with a working fluid. The heated fluid produces steam that drives a turbine to produce electricity.

The SolMaT program is designed to facilitate manufacturing approaches that can substantially reduce the near-term cost of solar thermal hardware and pave the way for early market deployment. The heliostat is a critical component, and a field of heliostats accounts for 50-60 percent of the cost of a power plant.

During the next phase of the project, additional heliostats will be installed at Sandia National Laboratories in Albuquerque, NM for optical testing and at Solar Two, a pilot power tower plant in Daggett, Calif., for extended field tests. Each unit will undergo a test program to build a better understanding of its design, fabrication, installation, performance and reliability. This is a key step toward the first 50-megawatt, electric power tower plant to be sited in the national solar enterprise zone in the southwest desert.

Employee-owned SAIC provides high-technology products and services to government and commercial customers in the areas of energy, environmental systems and engineering, information technology, systems integration, national and international security, telecommunications, transportation, and health systems and services. With annual revenues of $2.4 billion, SAIC and its subsidiaries have more than 24,000 employees at offices in 150 cities worldwide. More information about SAIC can be found on the Internet at