The second coming of solar power

More than just an environmental breakthrough, a new generation of photovoltaics can improve life in remote communities.

Craig Cox| September 2007 issue
For 40 years, scientists and environmental activists alike have been eagerly awaiting the dawn of the solar age, a time when humans could finally harness the sun’s power and begin to wean themselves from fossil fuels and nuclear power.
Their enthusiasm is understandable. The Earth collects more energy from the sun in an hour than its inhabitants use during an entire year. With solar panels occupying a mere one-half percent of its mainland, for instance, the U.S. could meet its entire electricity demand.
Yet through energy crises and oil wars, solar enthusiasts have watched as other renewable-energy alternatives like wind power and hydrogen got all the attention (and investment) while their once-shining star seemed to fade nearly to black.
But last year, solar power was suddenly making headlines again as Microsoft and Google announced plans to outfit their Silicon Valley campuses with state-of-the-art solar-energy systems. Perhaps even more startling, retail giant Wal-Mart had begun soliciting bids to rig solar panels on a number of its stores. Suddenly, solar was hot.
Actually, it’s been heating up for some time. The state of California is investing $3 billion in its “Million Solar Roofs” initiative, and Germany has created a substantial market for solar-power producers. All told, the solar market worldwide has been expanding 40 percent a year since 2000, hitting nearly $11 billion in sales by 2005.
That still accounts for only a tiny portion of total energy generation (.04 percent in 2006), but advocates say there’s never been a better opportunity for solar technology to make an impact worldwide.
Capturing energy from sunlight, A process called photovoltaics (PV), is not a new idea. In 1905, Albert Einstein was the first to describe the photoelectric effect, the principle on which photovoltaic technology is based—research for which he received the Nobel Prize in 1921.
But it wasn’t until the U.S. launched the Vanguard I satellite in 1958 that photovotaic cells found a long-term practical application. The first orbiting vehicle powered by the sun, the satellite circled the Earth for six years before the system shut down.
Since then, PV technology has become a trusted and reliable power source for spacecraft of all types. But adapting such technology to commercial use has proven more challenging.
Elliot Berman, a scientist whose research was funded by the Exxon Corporation, is widely credited with designing the first economically viable solar cell. His research in the 1970s dropped the price of solar technology from $100 per watt to $20 per watt—still far too pricey for residential applications, but perfectly adaptable to some commercial uses, such as navigational warning lights and horns.
In the intervening years, manufacturing improvements gradually lowered the price still further, to less than $3 per watt—which approaches the point that it becomes competitive with energy sources such as coal and nuclear power.
Remarkably, all this has come about while the solar industry has been working with what is essentially inferior technology. Photovoltaic cells have typically been produced from crystalline silicon, a material that Berman, who remains one of solar power’s most-passionate advocates, describes as “an inefficient absorber of light” that requires substantial amounts of energy to produce.
The key to solar’s future, Berman and his colleagues say, is so-called “thin film” technology, which employs semiconductors made from highly efficient light absorbers such as copper indium selenides, cadmium telluride and silicon-hydrogen alloy. “These materials need only one-hundredth of the material of crystalline silicon,” Berman explains.
Such thin-film solar materials have been in common use for 20 years, he notes, pointing to the light-powered watches and calculators that have become nearly ubiquitous. More recently, thin-film cadmium telluride systems have been operating on a large scale in Germany, and copper indium selenide systems are expected to be available for large-scale production before the end of the year.
Thin-film technology does offer hope for solar enthusiasts who believe it can reduce manufacturing costs enough to make photovoltaics competitive with fossil fuels. But it’s going to be up to enterprising researchers and visionary companies to push these options into the marketplace.
“Photovoltaic devices have been shown to be effective sources of electricity. All that is required for PV to become important is a two- to three-fold reduction in cost, which I believe will be accomplished by thin films,” Berman says. Government can play a role in promoting solar power by removing institutional obstacles to its use and actively implementing PV systems.
That’s what the Melbourne, Australia, city council has done as part of its Zero Net Emissions by 2020 program, an innovative partnership with local businesses designed to promote environmental quality. The city’s landmark 19th-century shopping complex, the Queen Victoria Market, has been retrofitted with 1,300 solar panels, making it the nation’s largest single urban solar installation connected to the grid. And the city council’s new office complex, Council House 2 (CH2), is the first public building to warrant the government’s new Green Star rating.
“We hope that CH2 will change the way that buildings are designed and constructed in Melbourne, Australia, and ’round the world,” Lord Mayor John So told Worldwatch Institute, the U.S. environmental research organization, published in its State of the World 2007 report.
But with new signs that oil supplies have reached their peak at the same time as China and India increase the demand, are these improvements in solar power enough to forestall a major energy crisis?
Berman offers a mixed forecast. “Solar technology alone is unlikely to prevent fossil fuel shortages,” he says. “Solar will be effective in replacing fossil fuels currently being used for non-transportation electricity generation. The best way to prevent liquid fuel shortages is to make and use more- efficient vehicles. We need to conserve our carbon resources for other uses, such as polymers and pharmaceuticals.”
Forty years ago, some 2 billion people had no access to electricity. Berman is quick to point out that this number has not changed. To him, the greatest promise of solar energy has less to do with powering Western homes and automobiles than with bringing electricity to the far reaches of the globe. “My interest in PV is in using it to provide electricity to the 2 billion people that have none,” he says. “To this end, I believe PV is an ideal source, since sunlight is provided already.”

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