Amorphous silicon solar technology once seemed promising enough to gobble up a large market share. But it seems to have fallen out of favor in the past year, particularly since Applied Materials announced a year ago that it would no longer sell equipment to make amorphous silicon solar panels. Not only have some of its customers struggled to scale up manufacturing, the customers of its rivals also have had trouble doing the same because of financial or technical difficulties.
But amorphous silicon technology isn’t dead, as Tom Cheyney at PV-tech showed in this story. In fact, DuPont, better known for its materials that encapsulate and protect solar cells from moisture, ultraviolet radiation damage and other environmental enemies, has been churning out amorphous silicon solar panels at its factory in Shenzhen, China, through a subsidiary called DuPont Apollo.
DuPont Apollo began production in the fourth quarter of 2009 with two lines that could produce 50 megawatts of panels per year, said Marc Doyle, global business director of DuPont photovoltaic business unit. DuPont has since improved the yield and efficiencies to reach nearly 80 megawatts of annual capacity on the same lines, he said.
Like any new solar technology, amorphous silicon production has higher startup costs than more common technologies that use materials such as silicon. But the costs should come down with mass production, and structurally, amorphous silicon thin films are simpler than other thin film technologies, Doyle said.
“Thin film silicon is as simple as it gets. It’s really glass and gas and encapsulant,” Doyle said.
Amorphous silicon solar panels on the market now tend to covert a lower percentage of sunlight into electricity than those made with silicon or compounds such as cadmium-telluride and copper-indium-gallium-selenide. Manufacturers of amorphous silicon thin films typically report 10 percent or less efficiency, while their competitors are able to claim a few percentage points higher or more.
Doyle contended that amorphous silicon solar panels can produce more power each day than silicon solar panels because of their ability to convert diffused light into electricity.
Doyle declined to provide manufacturing costs or pricing for DuPont’s panels, but said prices in the solar market usually reflect the efficiencies of the panels in order to attract buyers.
DuPont’s panels come in 140 watts, 145 watts and 150 watts, and their average efficiencies are up to 10 percent, Doyle said. DuPont unveiled the 150-watt panel in February this year and will start selling them later this year. All of its panels are double-junction, which means the panels have not only a layer of amorphous silicon but also a layer of microcrystalline silicon to help boost their efficiencies.
The company bought factory equipment from a variety of manufacturers, which Doyle declined to name. The equipment didn’t come from Applied though.
DuPont actually didn’t set out to become a large solar panel maker. The company was interested in exploring new solar market segments for its encapsulants and other materials, and it already was developing materials for amorphous silicon and other thin film solar technologies. The company decided to set up a R&D center in Hong Kong and the solar panel factory in China because it wanted to be an early thin film provider to what it believed would be a booming domestic market.
China isn’t the world’s largest solar market (that would be Germany), but it is vying for that spot with the United States. Chinese government’s new five-year plan, released in March this year, called for adding 5 gigawatts of solar. China has announced government incentives for solar installations in recent years, but it hasn’t moved as quickly as some manufacturers had hoped to implement some of the incentive plans.
China also is home to some of the world’s largest solar panel makers. Those panel makers, such as Suntech Power, Yingli Green Energy and Trina Solar, make silicon solar panels and are much larger than DuPont.
DuPont wanted to see its solar panels in ground-mounted arrays or used as part of a building architecture. The building market is so tiny that some analysts and manufacturers have relegated it to a niche market that may not be worth tackling.
"It's not a huge market, but we see it as becoming an interesting market in the future," Doyle said. He added that DuPont is developing a process that increases a solar panel's transparency while minimizing its efficiency losses. "Theoretically, if you have 20 percent transparency, then you should only lose 20 percent of the watts. In reality you lose 25-35 percent of the watts. We work to bring that to an equal footing."
DuPont has been able to see its panels and is focused on Southeast Asia. The company has sold out what it expects to produce for 2011. The company has said very little publicly about its customers. In May, it announced a supply agreement with Wipro EcoEnergy in India, but it declined to disclose the volume. Another Indian company, Moser Baer, also has said it would use 10 megawatts of DuPont’s solar panels for a solar power plant in the Indian state of Gujarat.
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