Selection and design of a stretched-membrane heliostat for today's markets

Science Applications International Corporation has designed a complete, integrated stretched-membrane heliostat. The present state-of-the-art is a single-pedestal that does not take advantage of the unique characteristics of stretched-membrane mirror modules and does not allow face-down stow. It was desired to seek more cost-effective designs for use with stretched membrane mirrors. Many stretched-membrane heliostat drive system designs were generated and evaluated relative to the pedestal design. The two most promising alternate designs were determined to be a dual module design and a shared support design. Further refinement and cost analysis led to the selection of the dual module heliostat as the preferred design. The dual module design was estimated to cost about 18% less than a pedestal heliostat over its lifetime, and was determined to have the best near-term development potential of all the designs studied. This design incorporates long-sought features such as face-down stow as well as proven technology such as the single pedestal-mounted drive unit. A 100-m{sup 2} dual module heliostat was designed. Detailed design studies and manufacturing cost estimates were performed. The SAIC dual module heliostat is structurally optimized and cost efficient. At a production rate of 5000 heliostats per year, the installed cost of the dual module heliostat is estimated to be $$107/m{sup 2} ($$10/ft{sup 2}) and the total lifetime cost (including O M costs) is estimated to be $$139/m{sup 2} ($$13/ft{sup 2}). 11 refs., 63 figs., 11 tabs.