Big is beautiful; utility-grade solar is becoming practical.

In the struggling industrial city of Brockton, Massachusetts, city officials have opened a tiny utility-scale solar electricity plant on the four-acre site of an abandoned gas plant. The rows of solar photovoltaic panels began generating an average of 425 kilowatts to the grid in September 2006, turning a vacant lot of capped coal-tar residues into the largest utility-scale solar PV facility in the U.S.

The Brockton Brightfield, which opened in September 2006, provides electricity to the grid equivalent to the needs of about 70 households. It's one small example of how we can harness the sun's potential as a large-scale electricity source.

The Brockton Brightfield represents an expansion of the home-based photovoltaic array, using larger PV panels produced by Schott Solar in nearby Billerica, Massachusetts. Travis Bradford, who runs the solar-oriented Prometheus Institute and wrote the book Solar Revolution, says utility-scale solar energy will fill an important need, but thinks that solar PV on the roofs of houses and businesses will become the real norm in America.

"I don't want to dismiss all of these centralized solar technologies," Bradford says. "For the next 20 years utilities will be adding them to meet renewable portfolio standard goals. But in the end, distributed PV makes it easy and cost-effective to deliver electricity to the point of use."

Concentrating solar power has been in use for decades, but is still treated as a new technology. Florida Power & Light Energy, an independent power producer, has been running a concentrating solar power plant in the Mojave Desert of California for some 20 years. This year, power companies in the U.S., Germany, Spain, South Africa and elsewhere are planning or building major solar electricity plants using the technology.

There are four ways to produce concentrating solar power, but so far only one has seen commercial use in the U.S.: parabolic trough technology. Long parabolic-shaped rows of mirrors focus sunlight on fluid-filled metal tubes encased in glass. The heat collected drives steam generators similar to those that run coal-fired power plants to make electricity.

An independent power producer, Solargenix, is building the first concentrating solar plant to go up in the U.S. in 15 years, in Nevada. The plant will serve about 40,000 households, and will be called Nevada Solar One (Schott Solar is providing the tubes). A small (one-megawatt) plant is being built outside of Tucson. In Spain, where the sunlight is less abundant than in the American Southwest, but where electricity is very expensive, new energy tariffs have led to the construction and planning of three concentrating solar plants. At least half a dozen other concentrating solar power plants are in the works around the world, said Mark Mehos, the program manager for concentrating solar power at the National Renewable Energy Lab, a federal research facility, in Golden, Colorado.

In a report published in January by the American Solar Energy Society, experts predict that solar PV panels, set up everywhere from people's roofs to parking lots to brownfields such as the one in Brockton, could provide seven percent of total U.S. electricity needs by 2030. That would be about 200 gigawatts of capacity, according to the report, "Tackling Climate Change in the U.S."

The report makes the somewhat dizzying prediction that concentrating solar power, which always works on a utility scale, could provide seven times of all of America's power needs. This expands on a prediction green advocates have made for years, arguing that, potentially, all of the country's power needs could be met in a 100-square-mile plot of land in a sunny region like Nevada. In reality, there are numerous challenges associated with today's solar technology, from the cost of building the facilities to the logistical difficulties of transporting the electricity.

The report does go beyond theory to predict two scenarios: the more radical one is that, by 2030, concentrating solar power plants could provide 80 gigawatts of power, provided that a $35-per-ton carbon tax went into effect. If the current federal tax credit were extended, the report predicts that concentrating solar power could provide 30 gigawatts of power, or three percent of the country's needs.

State governments are beginning to push for alternative energy, and last year the Western Governors' Association recommended building four gigawatts of utility-scale solar plants in California, Arizona and other southwestern states.

In Germany and Spain, where even fossil fuel-driven electricity is expensive, policies support the fast production of solar technology. Even though the U.S. has fallen behind in the solar manufacturing industry, it will benefit from the global solar market which lowers the overall cost.

"What we have lacked--and it really is unfortunate because these technologies were developed here--is a national energy policy that places a priority on establishing clean, sustainable, renewable energy as a mainstay of our energy portfolio," says Marc Roper, a vice president at Schott Solar.

Not only does solar provide a free power source, but it operates quietly and can be located almost anywhere.

Right now, photovoltaic panels on rooftops cost about $10 per watt to install. In Brockton, the cost was about $7 per watt. Concentrating solar power systems are approximately half of that cost, Mehos says. New policies, incentives and economies of scale would further lower the price, bringing utility-scale solar power plants mainstream.

"There is plenty of resource to power the country," Mehos says. "The next question is: Do we have the political will?"

CONTACT: American Solar Energy Society, [phone], www.ases.org.