Thin Film’s Time in the Sun

The low manufacturing costs of photovoltaics that employ thin films of cadmium-telluride semiconductor have long been seen as having the potential for lifting solar power from its niche status as a very expensive power source, delivering less than a twentieth of 1 percent of U.S. electricity.

Now, after two decades in which cadmium-telluride technology was dogged by low power output and reliability problems, it’s suddenly elbowing its way into renewable-energy markets and competing with today’s dominant solar technology: silicon solar panels. The company behind this technology turnaround is Phoenix-based First Solar, which says that the technology could eventually be cost competitive with conventional fossil-fuel sources of electricity.
First Solar has racked up a string of large contracts and investments over the past year for its thin-film technology. First Solar closed a $400 million initial public offering in November and clinched a deal three months later to supply a 40-megawatt solar-panel farm in Germany that will be one of the world’s largest. And earlier this month, the company revealed that it has signed long-term contracts with European and Canadian buyers to supply 685 megawatts of modules worth $1.28 billion. The latter figure is especially impressive considering that all the solar-module factories in the United States shipped less than 200 megawatts’ worth of photovoltaics last year.

Ken Zweibel, who directed the U.S. National Renewable Energy Laboratory’s (NREL) Thin Film Partnership Program for more than a decade, says that First Solar has “broken out of the pack” by simultaneously achieving low-cost mass production and respectable power output. Zweibel, who left NREL in January to launch his own thin-film company using similar technology, expects more improvement on both fronts. “Cadmium telluride has a clear route to cost competitiveness with conventional energy,” he says.

Thin-film panels are produced by layering shallow coatings of semiconductor materials on sheets of glass, plastic, or metal–a seemingly simple concept that is hard to implement on a large scale. Cadmium-telluride panels in particular seemed finished five years ago when BP Solar, an arm of the London-based oil company, shut down what had been the largest cadmium-telluride commercialization effort.

Technology Review