Science & Technology: ENERGY
SUNUP AT LAST FOR SOLAR?
Steven Strong became a solar-power convert while working on one of the world's largest oil reserves. As an engineer in the early 1970s, he helped design power stations along the Alaska pipeline. The challenges in transporting fuel across the vast wilderness persuaded him that "saving a unit of energy is far easier than producing it."
Returning to Boston, he started Solar Design Associates to make energy-efficient houses. Strong eschewed bulky rooftop arrays for collecting the sun's energy. Instead, he embedded semiconductors that convert sunlight to electricity, called photovoltaic cells, directly into walls and roofs. But the materials were expensive, and only well-heeled enthusiasts signed up.
Now, 20 years after Strong pioneered the concept, such "building-integrated" photovoltaics are looking a lot more viable. For one thing, solar cells cost just one-third what they did in 1980. Contractors and homeowners like building-integration because the new components replace conventional building materials, effectively reducing the cost. And utilities are attracted because solar cells will generate surpluses during peak daytime hours, creating an energy pool that power companies can tap.
POLARIZED. Building-integration is just one of the trends fueling a global boom in photovoltaics. The market is still tiny--just $310 million in 1994, according to consultant Paul Maycock of PV Energy Systems in Catlett, Va. But it's growing 30% a year. Assuming devices continue to get cheaper and more efficient, "it's very likely that solar power will be fully economic" by early in the next century, Maycock predicts. By then, the world market could surge to $7 billion a year.
Today, most of America's 100,000 solar-powered houses are rural dwellings not connected to a utility grid. Indeed, utilities have been traditionally wary of alternate energy schemes. And they are still polarized on the subject.
But gradually, a core group has been converted. One of the most forward-looking, the Sacramento Municipal Utility District (SMUD), is installing rooftop arrays on hundreds of houses. SMUD and 90 other utilities have banded together to promote photovoltaics. They're prepared to spend $368 million over five years, backed by $130 million in government seed money.
California isn't alone. In Texas, City of Austin Electric Utility has spent $4 million to put photovoltaics in its service area. It's also footing the bill for rooftop systems on dozens of houses. Austin swallows the extra cost--and even pays customers for the use of their roofs. Why bother? "It's an investment in the future," says John Hoffner, who runs the program. When the buildings start generating surplus electricity, Austin can draw on the pool.
The New York Power Authority has a similar plan to install 50 roof systems over the next five years. It has assembled a consortium of buyers to purchase 10 megawatts worth of cells over five years, starting in 1997. The aim: to lower the cost of solar modules from $5 per peak watt today to $1.50. Mark Kapner, the utility's alternative-energy manager, says solar power could possibly compete with grid electricity in New York City and Long Island by 2000.
"GREEN" IMAGE. With strong support from this vanguard of utilities, the building-integrated movement is quickly gathering steam. Under a cost-sharing program with the Energy Dept., two companies--United Solar Systems Corp. in Troy, Mich., and Solarex Corp. in Frederick, Md.--will soon introduce products such as solar roof shingles for houses and opaque glass facades--or "curtain walls"--for commercial buildings.
Building owners who budget for premium materials can save money by using the new solar components. Curtain walls from Solarex--a joint venture of gas and oil giants Enron Corp. and Amoco Corp.--should cost less than high-end materials such as marble, and generate electricity to boot. They bestow a valuable "green" image on commercial buildings. And there's a natural appeal for homeowners. Says analyst Bob O. Johnson of Strategies Unlimited Inc. in Mountain View, Calif.: "For less than the price of a full-size automobile, you can buy a roof that takes care of your energy needs for the next 25 to 30 years." In a best-case scenario, Arthur D. Little Inc. reckons the U.S. building-integrated market could hit $2.6 billion in 2005--provided utilities rev up purchases.
Why has solar power taken so long to catch on? Economics, mostly. Manufacturing crystalline silicon devices--semiconducting crystals of silicon laminated to glass--is an expensive proposition that involves casting the material into ingots at high temperatures. The materials aren't cheap either. As a result, solar energy is still twice as expensive as utility power.
SHAVING COSTS. New types of solar cells, such as thin-film devices, offer a possible solution. They're produced by depositing a silicon-alloy vapor on glass or metal--a relatively inexpensive process. And unlike atoms in crystals, thin-film atoms are randomly arranged--or "amorphous"--which ensures better light absorption. Amorphous silicon thus requires just 1% of the costly photovoltaic material that the crystalline form needs. Shaving costs in this way, manufacturers should be able to cut the price of solar modules in half by the end of the decade, says Scott Sklar, executive director of the Solar Energy Industries Assn. in Washington.
Thin-film efficiency is still low--just 6%, compared with 13% for crystalline silicon. But scientists at United Solar, which is partly owned by Canon Inc., have pushed it as high as 10% in the lab. And thin films got a big vote of confidence in June, when Solarex announced plans to build a 10-megawatt thin-film plant in Virginia.
Skeptics point out that commercial success hinges on support from Washington at a time when budgets for alternative energy are under the scalpel. Last month, the House Appropriations Committee voted to cut allocations for solar and other renewable energy technologies in half, to $201.6 million, for the fiscal year beginning Oct. 1.
Solar supporters in the Senate, though, remain optimistic. They hope to limit cuts when the Senate Appropriations Committee meets later this month. Further on the fringe, advocates like Steven Strong think the building-integrated movement could usher in the long-awaited Solar Age, where town buildings become power producers, giving new meaning to the phrase "a thousand points of light." They envision a world with no brownouts and no need to scour the globe for the last drops of oil. Of course, similar dreams have inspired solar visionaries for over a century. But if building-integration captures the public imagination, they could finally find their place in the sun.By Ingrid Wickelgren in New York