Based on an emitter-wrap-through (EWT) photovoltaic (PV) design technology, Advent Solar (Albuquerque, NM) took first place in a field of 35 companies at the 2003 National Clean Energy Venture Competition in Austin, TX, in November 2003. The competition, sponsored by Bechtel (San Francisco, CA), took place during the 16th annual industry growth forum held by the National Renewable Energy Laboratory (NREL; Golden, CO). Originally developed and patented by James Gee at Sandia National Laboratories (Albuquerque, NM), EWT technology enables the use of ultrathin wafers to cut PV manufacturing costs while using an established crystalline-silicon technology. Advent acquired a license for the technology from Sandia along with Gee, who is now Advent's chief technology officer.
The previous year's outstanding presentation winner, HelioVolt (Austin, TX), described its patented technology for efficient mass production of copper indium gallium diselenide (CIGS) solar cells (see figure). HelioVolt is currently developing its fabrication process as part of a $100,000 cooperative research and development agreement with NREL.
The HelioVolt thin-film PV process involves depositing two thin chemical-reactant layers and rapidly heating them to bond CIGS films to sheets of glass or other surfaces. It is one of several thin-film technologies that hold promise for lowering the cost of solar cells in the commercial market.
"The thing that has been attractive about the HelioVolt technology is the potential for moving a little bit away from conventional vacuum-deposition processes to a technique that's akin to printing," said John Benner, a research manager at the NREL National Center for Photovoltaics. "The layers are reacted and transferred under high pressure and rapid thermal processing."
Involvement of large PV companies has primarily occurred outside the United States, led by companies such as Sharp (Osaka, Japan), Shell (The Hague, The Netherlands), British Petroleum (London, England), Sanyo (Osaka, Japan), and Kyocera (Kyoto, Japan). The international PV growth rate has exceeded 30% a year for the past five years, climbing to about 50% in Japan and dropping to about 10% in the United States, said Benner. Japanese and European growth has benefited from major initiatives to increase the use of clean-energy technologies.
Interest in PVs is picking up among large U.S. firms, however. In 2002, worldwide production was on the order of 500 MW of new modules, many of which are selling in the range of $3 to $5 a watt, with systems selling in the $6- to $10-per-watt price range.
The U.S. Department of Energy receives $70 million to $75 million from Congress annually for development of PV technologies—the cells, the physics, the systems, the modules, and so on. The National Center for Photovoltaics retains about 50% for in-house research and distributes the other 50% in a coordinated program of university and industry research. Next-generation research programs are focusing primarily on thin-film silicon and polycrystalline compounds of cadmium telluride and copper indium diselenide. "The basic material system is reasonably well established," Benner said. "Our scientists at this laboratory have made devices as high as 19% efficiency in copper indium diselenide."
Several companies are in various stages of PV manufacture; Shell Solar, with a U.S. facility in Camarillo, CA, is probably one of the largest companies in the polycrystalline thin-film area, Benner said. "They just announced plans to boost their production capacity to 12 or 20 MW," he said.
In addition to the fact that the PV business has grown into the several-billion-dollar range, interest is also being driven by concerns about global climate change and a sharply rising demand for natural gas that may exceed availability. "A number of different business models seem to be promising," said Benner.