GW Scale

REhnu’s large solar farms (typically 1 GW each), will achieve the full advantage of economy of scale for generator installation as well as manufacture. Units will be assembled in a facility located at the center of the farm, from components delivered to the site. For example, the silvered glass reflector dishes will be delivered in stacks, directly from the float-glass factory, for integration with prefabricated steel members.

Layout and deployment of generators

Completed units are set out on the farm in a triangular grid pattern on 78' centers. The assembly and maintenance facilities are at the center, with narrow access roads running between every other row of generator units. Clearance needed for installation or washing is obtained by turning units parallel to the road. Such direct access by road to every unit from the central assembly facility allows installation and reflector cleaning operations to be fully mechanized. An optimally sized single farm of gigawatt scale will cover 6 square miles, with the longest distance to transport a generator out from the assembly facility being 2.5 miles.

Annual energy yield

A REhnu farm of 33,000 30 kW generators, each with 110 m2 collecting area and overall conversion efficiency of 27%, delivers power of 1 GW to the grid when the solar input power is 1 kW/m2. The annual energy yield depends on the annual average direct solar flux at normal incidence, which across most of Arizona and southern California is between 7 and 8 kW-hr/m2/day, modified by shadowing when the sun is low. The long horizontal profile of REhnu’s generators minimizes self-shadowing, despite the farm’s close-packed layout, to less than 10%. Thus, depending on location, the actual annual yield will be 2.3—2.6 billion kW-hr/year, about a quarter the output of a coal-fired plant running continuously at 1 GW.

The detail shown at the top of the page, with each elongated 2 x 6 generator shown in a different color, illustrates self-shadowing in the bottom right corners. The view is from the sun at 18° elevation, as it is, for example, at 3½ hours past noon on a midwinter’s day at 33° latitude. The shadowing at this time is less than 10%, thus high output power is maintained even in winter, for nearly seven hours on a clear day.