Numerous promotion programs in Germany and Japan have triggered a veritable photovoltaic boom. While this has spawned some happy consumers, cell producers are slowly finding themselves in dire straits: a bottleneck is threatening the supply of silicon waste from the semiconductor industry. Currently, this gap in the supply of raw materials is being filled through the use of pricey, electronic-grade silicon, which is available as a result of the economic slowdown in the microchip sector. However, if the photovoltaic industry doesn´t succeed in acquiring its own source of solar-grade silicon in the next few years, it will have to prepare itself for a rude awakening: the price of solar modules will rise. (...)

Franco Traverso laments the situation in his uniquely passionate manner: "panicky, confused, terrible" are the words that the Italian uses to describe the mood in the photovoltaic industry.
Traverso, head of the module production company Hellos Technology in Carmignano di Brenta near Padua, insists, that the industry should have addressed the silicon problem long ago.
Traverso´s warning is nothing new: He first gave it five years ago. In 1996, it already appeared as if the raw material for solar cells would soon run out, because the PV industry was covering itself by using rejected silicon material from the semiconductor industry. (...)

Peter Woditsch, the technical CEO of SolarWorld´s subsidiary Deutsche Solar GmbH, which produces solar wafers in Freiberg, Saxony, Germany, estimates that producers will be able to sell just 15,000 tons of the 25,000-ton world capacity of EG silicon in the semiconductor sector this year. About 2,700 tons of EG silicon will be on the market for the photovoltaic industry this year. Without this source, solar cell producers would already have felt the pangs of a serious raw material deficiency in 1998 (...)

Even Hubert Aulich, board member of the Erfurt-based solar-grade silicon (SoG) and wafer producer PV Silicon AG, which recently joined forces with the British polycrystalline ingot producer Crystalox (see Pi 7/2001, p. 7), realizes that producers of EG silicon no langer view deliveries to the photovoltaic industry as an "unimportant side-business." However, Aulich also insists that the suppliers won´t be able to simply increase the amount of silicon at will - especially if the semiconductor market recovers. If that does happen, then buyers from the PV industry won´t offer silicon suppliers any chance for significant profit margins. According to Aulich, whereas the PV industry pays between $27 and $30 USD per kilogramm of low-quality EG silicon, the semiconductor industry pays between $40 and $60 for high-purity EG silicon. The PV industry would have to start paying that much too when its old sources dry up. "We´re used to paying $20 to $24," says Aulich. "There´s nothing else we can do - we need our own solar-grade silicon production." The European Photovoltaic Industry Association (EPIA) believes it is necessary to ensure the "widest possible" political and economic engagement on this issue. A 1999 study for EPIA by Bayer AG and Rome-based L.I.F.E. Ltd. concluded that a silicon source independent of the semiconductor industry is needed by 2004 or 2005. But it would take up to five years to get a SoG silicon factory rolling, and this would cost 100 to 150 million EUR (...)

According to the latest figures, which Koch and Peter Woditsch of Deutsche Solar presented at the June meeting of the European Material Research Organization in Strasbourg, the photovoltaic industry, which has a conservatively estimated 15 percent annual growth rate, will require about 5,850 tons of silicon worldwide in 2005. Of this total, only an estimated 2,300 tons will be covered by waste from the semiconductor industry. It is hardly plausible that the remaining gap of 3,550 tons could be filled with EG silicon at reasonable prices. (...)

Research projects have been conducted since the 1970s with the goal of developing a process that meets the quality needs of the photovoltaic industry. Yet until now, the majority of these projects have been unsuccessful. However, among all these efforts, Bayer AG´s plan is one with a real chance for success, Bayer´s chemists didn´t try to reinvent the wheel, but have been working on an economical combination of already-existing technologies. (...)

Bayer researchers envision a factory with an annual production of 5,000 tons. According to calculations, SoG silicon could be sold at a price between 12 Euro and 13 Euro ($10.50 and $11.40) per kilogram - less than half of what the photovoltaic industry currently pays. Several process steps have already undergone laboratory testing. Nevertheless, a two-year pilot production with an annual volume of 50 tons will be necessary. At the earliest, the factory could be ready for production by the end of 2005.

Bayer halted its activities in this area after it sold its subsidiary, Bayer Solar, to SolarWorld AG last fall (see PI 9/2000, p. 12). The new owners of the firm, which was renamed Deutsche Solar GmbH, first had to negotiate with Bayer to acquire the patent for the process developed in the SoG silicon research project. On Aug. 15, SolarWorld announced the takeover of the patents, but didn´t disclose a price. They added that they are in discussions with two potential partners about carrying out the project. Negotiations should be finalized by the end of the year. When asked, Deutsche Solar´s Woditsch would say only that the partners are Europeans and from the chemical industry, and obviously it isn´t Bayer AG, since "otherwise they would not have sold us the know-how," says Woditsch. (...)

Politicians who support PV despite its being much more expensive than other renewable energies have argued that increasing demand for PV modules would lift supply and quickly lower prices as a result of bulk production. But if a silicon shortage does occur, this argument would become untenable, and the elimination of PV subsidy programs could be a consequence.

Johannes Bernreuter