Sunday, July 24, 2005

Utility-scale solar power generation "imminent"

The future of solar energy is looking positively sunny: Solar concentrators using highly efficient photovoltaic solar cells are promising to reduce the cost of electricity from sunlight to competitive levels soon.

"Concentrating solar electric power is on the cusp of delivering on its promise of low-cost, reliable, solar-generated electricity at a cost that is competitive with mainstream electric generation systems," said Vahan Garboushian, president of Amonix, Inc. of Torrance, Calif. "With the advent of multijunction solar cells, PV concentrator power generation at $3 per watt is imminent in the coming few years."

Herb Hayden of Arizona Public Service (APS) and Robert McConnell and Martha Symko-Davies of the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) organized an international conference held May 1-5 in Scottsdale, Ariz. where the efficiency gains were announced and discussed.

Solar concentrator systems have been under development with Arizona Public Service's solar research facility. Photovoltaic (PV) concentrator units are much different than the flat silicon photovoltaic modules sold around the world that average 13% efficiency. PV concentrators come in larger module sizes, typically 20 kilowatts to 35 kilowatts each, they track the sun during the day and they are more suitable for large utility installations.

Ordinary, flat-plate solar modules have their entire sun-receiving surface covered with costly silicon solar cells and are positioned at a fixed tilt to the sun. In contrast, Amonix's systems offer significant cost savings by using inexpensive flat, plastic Fresnel lenses as an intermediary between the sun and the cell. These magnifying lenses focus and concentrate sunlight approximately 250 times onto a relatively small cell area. Through concentration, the required silicon cell area needed for a given amount of electricity is reduced by an amount approximating its concentration ratio (250 times). In effect, a low-cost plastic concentrator lens is being substituted for relatively expensive silicon.

"We have seen steady progress in photovoltaic concentrator technology," said Hayden, Solar Program Coordinator at APS. "We are working with advanced multijunction PV cells that are approaching 38% efficiency, and even higher is possible over time. Our goal is to install PV concentrator systems at $3 per watt, which can happen soon at production rates of 10 megawatts per year. Once that happens, higher volumes are readily achieved."

With information from, the leading clearinghouse on renewable power news.

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