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The number-two thin-film photovoltaics company plans to hit 1-GW in manufacturing capacity by 2012, the chairman of United Solar Ovonic (Uni-Solar) told attendees at the IntertechPira Photovoltaics Summit in San Diego last week. Toward the conclusion of his presentation on amorphous (a-Si) and nanocrystalline thin-film silicon, industry maven Subhendu Guha said that the recent successful raising of hundreds of million dollars through a public offering of common-stock shares and repricing of senior convertible notes will allow Uni-Solar to "sustain growth" to the gigawatt level.

While it continues to ramp to 300 MW of nameplate capacity at its Michigan factory sites by 2010, the company has yet to decide where the additional manufacturing will be located, according to Guha. The decision "will be based economic and practical reasons," he explained, noting the wide range of states and countries whose incentive packages will be considered as part of Uni-Solar's new fab site selection process.


Uni-Solar's Guha has grid parity in his sights.


The rest of Guha's talk focused on amorphous silicon's place in the thin-film PV market, Uni-Solar's current a-Si and emerging nanocrystalline technologies, and the main target market for the company's 18-foot-long flexible laminates that represents 70% of its business: the building-integrated sector, and its many attractive feed-in tariffs.

With fiscal 2008 coming to an end June 30, he held to the midterm guidance of estimated growth of 119% for parent company Energy Conversion Devices compared to FY07; about $224 million of the nearly $249 million in corporate revenues comes from the Uni-Solar segment.

Fiscal 2009 should also surge in the 100% range, according to Guha, tying in with the thin-film sector's faster overall growth rate versus the silicon portion of planet PV. His optimistic forecast data showed thin film accounting for 21.4% of the 4.9-GW overall estimated market in 2008 [corrected]. Amorphous silicon will be the largest piece, representing about 40% of that burgeoning TFPV share over the next three years, edging the cadmium-telluride segment by a few percentage points. The demand-driven expansion should result in a doubling in FY09 of the approximately 50 MW of Uni-Solar panels shipped the previous fiscal year, he said.

Uni-Solar's manufacturing lines consist of football-field-long, roll-to-roll production toolsets, processing triple-junction a-Si PV cells on six rolls of flexible stainless steel alloy, each about 2.5 km long, all going through in a single run of about 65 hours. Once the company pushes to its goal of hundreds of megawatts of installed capacity, the combined factory floors should provide a jaw-dropping showcase of high-volume R2R prowess.

If the technology roadmap continues apace, the next-generation high-efficiency nanocrystalline-silicon multijunction cells will supplant the a-Si devices in a few years, Suha believes. With conversion efficiencies in the lab reaching 15% or better, the nc-Si process should go to pilot stage soon.

Pushing deeper into the technical realm, he explained that "the best material is grown with hydrogen dilution of the active gas. As the hydrogen dilution increases, there is a transition from amorphous to nanocrystalline structure. The highest quality materials for both the nanocrystalline and amorphous stages are obtained near the edge of this transition," so tuning the a-Si below the edge and nc-Si above it will get the best results.

With their high absorption characteristics, lack of light-induced degradation, and compatibility with a-Si alloy deposition, the nano films appear to be "ideal for the bottom cell of a multijunction structure." Guha did admit in response to a question following his talk that maintaining material quality and uniform deposition over a large area with such stacks of nanoscale (200-angstrom thick) layers is challenging.

Like the rest of the PV community, Uni-Solar's goal is grid parity, something that Guha believes the company can attain by 2012. With a current kilowatt-hour price point of 21 cents, or $2.37 per manufactured watt, the company will strive to reduce its costs by one-third in each of the respective areas of materials; manufacturing throughput and yield; and conversion efficiencies, labor costs, and miscellaneous other expenses to reach 8-10 cents per kWh, or $1.10 per fabbed watt, according to the firm's chairman.

If all goes well, 2012 is shaping up as a momentous year for Uni-Solar, the long-awaited tipping point when its gigawatt-scale and grid-parity dreams come true.