Recently, China's polysilicon companies have made new achievements in reducing costs. It is said that some companies have already controlled the cost per kilogram within 24 U.S. dollars. The direct correlation with the cost of polysilicon is the recycling of energy consumption and by-products during the manufacturing process. Since polysilicon has been listed as a "high energy-consuming and highly polluting product" since the "Circular on Suppressing Overcapacity and Repeated Construction in Some Industries and Guiding the Healthy Development of Industries" issued in September last year (ie, "No.38 Document"), Although more than a year has passed, whether polysilicon is "double high" is still one of the focuses of the industry. Since polysilicon is the basic material for new energy and electronic information industries, and is related to the cultivation and development of strategic emerging industries in China, it is more necessary for the polysilicon industry to be objective and rational.

Although China's R&D of polysilicon has a history of more than 40 years, it is only in the last five years that the industry has actually become large-scale. It should be said that in the early stage of industrialization, "high energy consumption" and "high pollution" were actually objective facts in a few enterprises. Under the circumstances of misplaced supervision, it may even become a common phenomenon. “No.38 Document” clearly requires the elimination of polysilicon production capacity with an integrated power consumption of more than 200 kWh/kg before 2011, and strict limits on the proportion of silicon tetrachloride, hydrogen chloride, and hydrogen emissions in reducing exhaust gas. In fact, for polysilicon companies, high energy consumption and high pollution are symbiotic with high costs. The reason why those “double high” companies can survive is because the rapid development of the global photovoltaic industry in recent years has made polysilicon materials in short supply. The rapid increase in prices allows those who produce polysilicon even in backward processes to earn high profits. It is the international financial crisis that really hit those "double-high" companies. In the second half of 2008, the spot price of polysilicon from the highest point of 3,000 yuan / kg "rational return" to 400 yuan / kg or so, its price has been lower than those "double high" companies' production costs, if not by improving the process technology to reduce Cost, these companies only have a stop.

At present, the trichlorosilane reduction method (ie, modified Siemens method) is a mainstream technology for polysilicon production. With this process, about 1 kg of silicon tetrachloride by-product will be produced for each kilogram of polysilicon produced. If we can choose a reasonable technology to recycle silicon tetrachloride and convert it back into trichlorosilane needed to produce polysilicon, we can solve the pollution problem and the high energy consumption of the unit product. At present, China’s leading polysilicon companies have already optimized the integrated power consumption of polysilicon production to below 150 kWh/kg through the optimization of the reduction system and the cold-hydrogenation process of silicon tetrachloride, which is far below the energy consumption limit stipulated in “No.38 Document”. .

In addition to the improved Siemens process, the industry is also seeking new process routes. Silane and metallurgical processes are the focus of attention, and their energy consumption is much lower than the improvement of the Siemens process. At present, many domestic companies have begun to try to use these new processes to produce photovoltaic grade polysilicon.

Previously, “No.38 Document” had made provisions for the capacity of new polysilicon projects to “have to be greater than 3,000 tons/year”. However, the author believes that the formulation of “No.38 Document” is aimed at improving the Siemens process. For companies that adopt new processes, You can consider relaxing restrictions.

To take a step back, even if the “high energy consumption” dysentery cannot be completely eradicated in the short term, it cannot become an inevitable reason for limiting the development of the industry. At present, the energy consumption per million yuan of polycrystalline silicon is about 330 kwh, but polysilicon is only a part of the photovoltaic industry. Under the current technological conditions, China's energy consumption per million yuan (including polysilicon production) is about 900 kwh. The data available for reference is that the energy consumption per 10,000 yuan in the iron and steel industry is about 3,900 kWh, and the energy consumption per 10,000 yuan in the electrolytic aluminum industry is about 6,000 kWh. In addition, solar cells produce more electricity than they consume during use. According to calculations, in a region of moderate light conditions in China, a 1 MW solar power generation system will generate approximately 1.3 million kWh of electricity per year, which is equivalent to an annual production of 160 kWh of electricity per kilogram of polysilicon. In other words, through photovoltaic power generation, polysilicon can “make back” all energy consumption in its production process in only one year, and the design life of photovoltaic power generation system is usually 25 years.

For “double high” issues, the state should encourage polysilicon enterprises to carry out technological transformation, expand production scale, and achieve closed-loop production, thereby reducing the energy consumption of the unit products and avoiding the emission of pollutants; at the same time, it must also focus on supporting the research and development of some enterprises and scientific research institutions. The new process route and rapid industrialization will enable Chinese companies to compete with international giants and allow the polysilicon industry to clean up the original sins of “high energy consumption” and “high pollution”.

At the same time, the environmental protection department must also assume regulatory responsibility. When the current price of polysilicon rises again, the environmental protection department should be extra vigilant: Are polysilicon production lines shut down during the international financial crisis? The reason for the re-operation is that the emission problem has been solved through process optimization, or because the price of polysilicon has risen above the company's production cost? If it is the former, of course, it should be applauded; if the latter is the case, if it is exposed to illegal emissions, it must be resolutely investigated and dealt with without mercy.