Thursday, August 21, 2008

Beginning a solar power industry

Spurred by California's renewable energy law, on August 14, 2008, Pacific Gas and Electric announced the launch of major photovoltaic facilities.[1] It is contracting with OptiSolar of Hayward, CA, to purchase the power produced by a 550 peak MW thin film, fixed mount photovoltaic plant and with SunPower of San Jose, CA, to purchase the power produced by a 250 peak MW crystalline, single-axis moving mount photovoltaic plant.

Both facilities are planned for sites in San Luis Obispo County, CA. OptiSolar filed a permit application[2] on July 18, 2008, for a Topaz Solar Farms project, describing a 6,200-acre site north of CA 58 (Carrisa Rd.) and spanning Bitterwater Rd. SunPower announced plans for a California Solar Ranch project to be built on a 2240 acre site south of CA 58 and east of Soda Lake Rd.

In 2007 Ausra of Palo Alto, CA, announced plans[3] for a 177 peak MW solar thermal plant to be built for PG&E on 640 acres in San Luis Obispo County, CA, near CA 58 and east of Bitterwater Rd. PG&E also has previous contracts to purchase power from 800 peak MW of solar thermal plants located in California's Mojave desert,[3] while Southern California Edison is building a 500 peak MW solar thermal planT there.[4]

Sites of the San Luis Obispo County facilities are planned in the northern and central Carrizo (or Cariso or Carrisa) Plain, a valley between the Tremblor Range to the northeast and Coast Ranges to the southwest. The southern part of the Carrizo Plain and adjacent parts of the Tremblor and Caliente Ranges are protected as the Carrizo Plain National Monument.[5] Located just north of the unincorporated town of California Valley, CA, the sites are about 150 air miles northwest of Los Angeles.

Carrizo Plain is about 40 miles long and up to 7 miles wide. Land is used mainly for dryland farming; much of the land is unused. Located in the rain shadow of the Coast Ranges, Carrizo Plain often has cloud cover from November through February but is usually sunny in warmer months. It receives on average about 8 inches of annual rainfall. It has experienced major earthquakes. The announced solar facilities will occupy a little over 10 percent of Carrizo Plain.

NASA records for average insolation around the Carrizo Plain solar facility sites are 5.1 KWh/sqm-day,[6] comparable to Scottsdale, AZ, and better than major European facility sites at Serpa, Portugal, and Brandis, Germany. OptiSolar estimates a 23% annual capacity factor for Topaz Solar Farm. SunPower estimates a 25% annual capacity factor for California Valley Solar Ranch. Compared to insolation and performance for the largest current photovoltaic plant at Brandis, the OptiSolar and SunPower estimates appear optimistic by about 15 percent, possibly justified by sparser layouts.

These projects have created a solar power industry in California, in which solar technology companies are constructing and in some cases WILL operatE industrial scale facilities.

[1] David Sneed, PG&E to buy power from 2 solar farms, San Luis Obispo Tribune, August 15, 2008, at Matt Nauman, PG&E, SunPower announce major solar deal, San Jose Mercury News, August 15, 2008, at

[2] Optisolar, Topaz Solar Farm Application Submittal, July 18, 2008, at

[3] Michael Kanellos, PG&E links with Ausra for 177 megawatts of solar thermal power, CNet News, November 5, 2007, at

[4] Michael Kanellos, Ausra goes for a gigawatt, CNet News, September 27, 2007, at

[5] U.S. Geological Survey, Carrizo Plain National Monument, 2004, at

[6] U.S. National Aeronautics and Space Administration, Surface meteorology and solar energy database, at