Environment Forum

Defense Department to test concentrating photovoltaic technology

By Todd Woody
December 7, 2010

Skyline Solar Array_CenterLine - cropped_1The United States Department of Defense has signed a deal with Silicon Valley startup Skyline Solar to test its concentrating photovoltaic technology at military bases in California and Texas.

The Pentagon, one of the nation’s biggest consumers of energy, has emerged as a driver of new green technologies in an effort to wean itself of imported oil, reduce its carbon footprint and improve national security.

Earlier this year, Navy Secretary Ray Mabus pledged that within a decade the U.S. Navy would obtain half of its energy on land and sea from renewable sources. Back in 2007, the Air Force commissioned SunPower to build what was then the country’s largest photovoltaic power plant at the Nellis Air Force Base in Nevada.

According to the agreement announced Tuesday, Skyline will build a 100-kilowatt solar array at Edwards Air Force Base in Southern California and another 100-kilowatt system at Fort Bliss near El Paso, Texas.

At first glance, the company’s power plants resemble solar thermal parabolic trough installations that deploy long rows of mirrors to heat tubes of liquid suspended over the arrays to create steam that drives an electricity-generating turbine.

Skyline’s system, however, is a purely solid state. Each 120-foot-long trough concentrates the sun on photovoltaic modules attached to the edges of the arrays. That boosts the solar cell’s electricity generation as does a tracking mechanism that allows the arrays to follow the sun throughout the day.

Such concentrating photovoltaic systems — which Skyline calls “high gain solar,” or HGS — have been a niche market due to their relatively high costs. But as solar cell prices decline and solar thermal projects get bogged down in environmental disputes, they have become increasingly attractive as they can be built near utility substations and plugged into the grid without the need to build expensive new transmission systems.

A rival, Amonix, agreed last month to supply concentrating photovoltaic technology to generate 28.5 megawatts of electricity for utility Southern California Edison.

Skyline, which is based in Mountain View, Calif., has pushed to lower costs by using common materials, such as glass and steel, and by designing the arrays so their components can be mass-produced by automotive manufacturers. The company struck a deal last yearwith the Michigan subsidiary of Canadian auto manufacturing giant Magna International to make components for its HGS 1000 solar system.

The technology works best in desert regions with intense sunshine, hence the military’s move to deploy the Skyline arrays in the Mojave Desert and in South Texas.

The Defense Department (or DoD) also wants to test the portability of the Skyline system.

“The HGS technology is expected to be the highest performance PV system with the lowest costs in hot, desert climates,” the department said in a statement. “This demonstration will lead to a complete PV system ready for broad deployment. The deployment process will be optimized for typical DoD sites, and redeployment processes also will be developed for non-permanent DoD installations.”

(Photo courtesy of Skyline Solar.)

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