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Until the year 2002, wafer-based crystalline silicon solar cells were almost exclusively the solar cell technology used for large-scale power plants. Since then, steady growth in the market share for thin-film technologies has been observed, although crystalline silicon technology still remains the most important solar cell technology used in large-scale PV power plants. The market share of thin-film modules, especially CdTe modules, has been continuously increasing in recent years, most notably in the German market. However, other countries like Spain, the USA, Italy and France have seen some large-scale CdTe-based modules being installed in power plants recently.

At First Solar’s corporate headquarters in Tempe, Arizona, a morale-boosting slogan adorns posters stuck to the outside of cubicle partitions: “MILESTONE MADE! TEN ONE ONE.” That’s “Ten,” for 10 years in business – at least in the company’s First Solar incarnation. The original firm Glasstech Solar, led by visionary Harold McMaster, actually set up shop in 1984, then became Solar Cells, Inc. in 1992, which begat the present entity in 1999. The middle “One” stands for the gigawatt’s worth of panels produced in the solar module factories in Ohio, Germany, and Malaysia – as well as the annual production capacity that will be ramped by the end of 2009. The final “One” stands for perhaps the biggest accomplishment of all – the dollar-per-manufactured-watt standard beaten by two cents by First Solar in the final quarter of 2008, a cost that has since shrunk to 93 cents per watt in the first quarter of 2009. But then, “Ten/One/0.93” doesn’t quite have the same ring.

A variety of thin-film technologies are now entering a volume manufacturing phase. The benchmark has already been set by First Solar, Inc. in its conversion efficiencies, volume ramp and lowest cost-per-watt in the PV industry. Large-area thin-film deposition is a critical process step, dictating cell performance, reliability and manufacturing throughput. However, adoption of thin-film solar cells has been limited in the past by relatively complex and costly manufacturing processes. The advent of rotating cylindrical magnetrons for sputtering is demonstrating the potential to significantly reduce thin-film manufacturing costs. In this paper we discuss the basics of the technology and the developments taking place with some of the leading suppliers of sputtering target technology for the PV industry.

Despite the low-cost, high-efficiency, radical form factor promise of many thin-film photovoltaic technologies, scaling these materials to large-volume production has presented a wide array of challenges. Because of the recent polysilicon shortage, an incredible amount of resources have been focused on this goal and many thin-film alternatives are now available.

Until recently, Solyndra had been one of the stealthiest thin-film photovoltaics operators, its glistening, prominently logoed headquarters building reminding tech-savvy commuters plowing up and down the I-880 corridor near Fremont, CA, of how little they knew about the company. But Solyndra has finally let the sunshine in and come out of the closet – even if it hasn’t quite changed some of its stealthy ways.

With the thin-film silicon industry facing the problems of high-quality material deposition at high rates and narrowing deposition process windows, the “no-drift regime” is an important part of this development. In the case of plasma-enhanced chemical vapor deposition (PECVD) of thin silicon films, the inconstancy of the concentration of silicon-containing particles (SCP) in the plasma leads to changes in deposition conditions, causing a deterioration of film properties, therefore decreasing the performance of the solar cells. During the last few decades, evidence about the process instabilities has been accumulated in different laboratories.

The reliability of United Solar Ovonic (Uni-Solar) triple-junction amorphous-silicon thin-film photovoltaic modules is critical to their success in an increasingly competitive PV market. Modules must show useful operating lifetimes of 20 to 30 years, and although module efficiency is very important, the total energy that a module will produce largely depends on its operating lifetime.

Transparent conducting oxides (TCOs) are a special class of materials that can simultaneously be both optically transparent and electrically conducting and, as such, are a critical component in most thin-film photovoltaics. TCOs are generally based on a limited class of metal oxide semiconductors such In₂O₃, ZnO and SnO₂, which are transparent due to their large band gap energy and can also tolerate very high electronic doping concentrations to yield conductivities of 1000S/cm or higher.

In recent years, a new generation of solar electric products has emerged from the lab into the global market: thin-film technologies that employ approximately 1% of the active, expensive photovoltaic material used by standard crystalline-silicon cells. Through a combination of cost advantages and new product applications, cadmium telluride (CdTe), amorphous silicon, and copper-indium-gallium-selenide (CIGS) thin-film PV have the potential to foster a paradigm shift toward distributed electricity generation at cost parity with other forms of energy.

Laser-based tools have become increasingly visible within R&D labs, pilot production lines, and as the preferred technology used by many turnkey suppliers. As equipment types however, relatively little is known about the differences in the laser-based tools used for solar applications within each of the c-Si and thin-film segments.