Polysilicon vs. Thin-Film: The Difficult Choice for Solar Cells

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Keywords: Solar cells. Shenzhen Suntech, which had initially focused on thin-film cells, made a difficult decision. The company has shifted the Shanghai factory, which was originally planned to produce thin-film solar cells, to manufacturing polysilicon cells. In early November, Wuxi Suntech’s new polysilicon cell factory in Shanghai began operations; this factory was converted from a thin-film cell plant that was under construction. Shi Zhengrong, chairman and CEO of Wuxi Suntech, said that thin-film batteries are not competitive due to their low conversion efficiency. Does Shi Zhengrong, who holds a PhD in the field of thin-film solar cells, giving up his efforts in this area signify a major shift in the development direction of solar cells? The cost advantage resulting from lower prices of polysilicon is significant. It is understood that currently, the cost of a thin-film battery production line is about three times that of a crystalline silicon battery, and the cost of related facilities is also several times higher than that for crystalline silicon batteries. What is even more critical for manufacturing companies is that thin-film battery technology evolves rapidly, requiring significant investment from these firms. This year, with the recovery of the photovoltaic industry, several newly listed companies engaged in solar cell manufacturing have, without exception, focused their development efforts on polycrystalline silicon cell production. According to the reporter’s research, companies such as Risen Sun, Sunflower, and Chao Ri Solar are all engaged in the production and sales of polycrystalline silicon solar panels as their main business. It is understood that one of the key reasons why thin-film batteries became a hot topic for PE investment a few years ago was the low amount of silicon used in their production process. According to industry insiders, the amount of silicon used in thin-film battery packs is only about 0.5% of that used in polycrystalline silicon battery packs. A few years ago, the price of polysilicon peaked at around 400 dollars per kilogram; after the financial crisis, it dropped to around 50 dollars per kilogram. As a result, the proportion of polysilicon in the total cost of batteries decreased from 50% to 25%, while the cost of thin-film batteries dropped by only 10% during the same period. Thin-film batteries thus lost their cost advantage. Pi Jiayin, a researcher at Guosen Securities, told a reporter from the Securities Times that entering 2010, since the subsidies provided by Europe to the photovoltaic industry were not reduced as much as expected, the sector experienced an unexpected period of rapid growth. A person from the Sunflower Company’s secretariat told reporters that the company’s shipments to Europe increased significantly in the first half of the year; orders from Germany and Italy accounted for a significant portion of these shipments, and there was a demand that exceeded the supply of products. Data shows that this year China’s photovoltaic industry capacity has increased from 4GW last year to 10GW, a growth rate of over 150%, with more than 90% of the products being exported. It is reported that, compared to polysilicon cells, thin-film cells have the disadvantage of a lower photoelectric conversion efficiency, which is generally around 7%, whereas the conversion efficiency of Wuxi Suntech’s polysilicon cells has reached over 19%. The secretary of Sunflower also revealed in a previous interview with journalists that since 2000, the solar cell industry has developed rapidly in China; polysilicon-based solar technology has become relatively mature, and it is a field that domestic companies generally pay close attention to and strive to develop. Thin-film solar cells require technological breakthroughs. The withdrawal of Suntech Wuhan from the field of thin-film solar technology does not, in the view of some industry experts, mean that there are no prospects for such cells anymore; it is simply a market-related decision made by Suntech Wuhan to make better use of its own technical advantages. Industry experts say that the thin-film cell products of First Solar in the United States have a conversion efficiency of 11%-12%. Wuxi Suntech is at a significant disadvantage, so it makes sense for it to choose to shut down its thin-film battery production lines. However, due to the technical advantage of thin-film solar cells in delivering good performance in low-light conditions, which is relevant to the construction of desert power plants, there are also many listed companies in China that use thin-film solar cells as a stepping stone to enter the photovoltaic industry. Among them, the first 26MW thin-film solar cell production line of Jiangsu Variety Photovoltaic Co., Ltd., which is under the Variety Group, was officially put into operation at the end of 2009. The company can supply amorphous silicon thin-film solar cells with an initial efficiency of 8.8% and a stable conversion efficiency of over 7% for the market. The company’s amorphous silicon thin-film project enjoys a certain cost advantage over its competitors, thanks to the use of ordinary glass and processes such as self-coated conductive films. In addition, Furi Photovoltaic Technology Co., Ltd., a subsidiary of Furi Group, mainly produces CIGSSe thin-film solar cell modules. CIGSSe technology features high efficiency, low cost, and long lifespan. It has the highest absorption coefficient for visible light and photovoltaic conversion efficiency among all thin-film solar cell materials; its photovoltaic conversion efficiency is close to that of current polysilicon cells, while the amount of raw materials required is much lower than that of traditional polysilicon solar cells. Therefore, industry experts point out that this type of product is the most promising efficient thin-film cell for achieving low-cost photovoltaic power generation. Zhang Wei, an analyst at Guotai Junan, commented that the aforementioned technology is likely the most promising thin-film solar cell technology available at present. First, the potential for improving battery efficiency is greatest among thin-film batteries. Second, the production technology for CIGSSe thin-film batteries has become increasingly mature, with an increasing number of manufacturers; as a result, costs are expected to decline further in the future.