Novel Lightweight, Low-Cost Heliostat for Concentrating Solar Power

Heliostats in use today are comprised mainly of many mirror facets which are mosaiced onto a structure with a reflective area of typically over 100 m2, and centrally controlled with long, wired connections. They are heavy and require large concrete slabs to support them. More recently, some companies have changed strategy and are investigating smaller area monolithic heliostats, nominally a few square meters with a single facet. These heliostats track and point with local controls, use a mounted small-area photovoltaic array for electrical power, and require just a rigid post for mounting, due to the much-reduced weight. Our proposed mirror facets address this new strategy well; the weight of our 4 m2 mirror facets are estimated to weigh 7 kg/m2 as opposed to existing facets using ~4 mm thick mirrors and metallic substrates and weighing upwards of 12 kg/m2. This competitive advantage allows not only for less support structure, but reduces shipping and labor costs, since our 4 m2 facet will weigh less than 30 kg. In addition, our facet cost per unit area is much less than conventional facets. At large volumes typical of utility-level concentrated solar power (CSP) facilities, the nominal cost of our facets is under $30/m2, in large volumes, possibly as low as $25/m2. The technical objectives of this proposed Phase I research and development effort are: (1) demonstration of L.Garde heliostat mirror fabrication scalability to large area mirrors, (2) development of the mirror support structure, (3) qualification of large area mirrors through field testing, and (4) development of path towards secure integration into nation’s electricity grid and cost models to determine cost of electricity to consumers. Although it is not possible for us to accurately calculate this effect on the LCOE of the system at this time, the weight reduction will impact the costs of shipping, handling, storage, labor and ancillary equipment. A 4 m2, 28 kg facet (~62 lbs) is easily transported and installed by two handlers, will require less structural support and a smaller motor for sun tracking. Therefore, it’s possible that this may translate to a total reduction in levelized cost of electricity (LCOE) of 20% or more.