The two big suppliers of equipment for amorphous silicon-based photovoltaic production, Oerlikon and Applied Materials, were all over Intersolar last week in San Francisco.

Chris O'Brien is the head of marketing development at Oerlikon, a century old technology company with 18,000 employees and overall revenue of $4.5 billion.

Oerlikon has sold more than 400 megawatts of thin-film manufacturing capacity, with more than 963,000 panels built and with 200 megawatts under contract.

According to O'Brien,

• "The fundamental drivers for growth have not changed."
• "There is still abundant room for growth."
• "Thin film will grow faster than the rest of the solar market."

O'Brien sees Oerlikon Solar's role as "growing a fleet of [a-Si] customers and making them competitive in the years to come."

Oerlikon's technology is "micromorph tandem junction a-Si." In addition to the a-Si layer, the micromorph cell has a tandem structure with an additional microcrystalline absorber. This layer converts the energy of the red and near IR spectrum.  Oerlikon claims that it has a cost roadmap to "reduce pricing from $1.50/W to $0.70/W" within a year and that its technology offers a reduction in labor, maintenance, capex, and opex.

Oerlikon guarantees a 9.3 percent efficiency for equipment it is selling today. 

But one needs a little bit of caution when considering efficiency numbers.  There has been talk about an 11 percent efficient Oerlikon module.  This is often quoted as "initial efficiency." 

Amorphous silicon exhibits a light-induced degradation of its optoelectronic properties called the Staebler-Wronski effect. This degradation effect is associated with the high diffusion coefficient of hydrogen and the changes in local bonding coordination promoted by hydrogen.

The U.S. program eliminated Staebler-Wronski instability in 1990/91 by insisting that only stabilized efficiencies be reported.  A champion module may show 20 percent degradation, so an 11 percent efficient champion module is no better than a 9 percent stabilized module.  Oerlikon has brought that instability back by reporting initial efficiency. 

Be careful in comparing efficiencies across different vendors and pay attention to that "initial efficiency."