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Polysilicon: an important raw material upstream of photovoltaic 2021

Since the second half of 2020, the price of China photovoltaic industry chain has ushered in a wave of price increase. Among them, the price of polysilicon has been rising all the way, so that downstream photovoltaic manufacturing enterprises can see the importance of ensuring the supply of raw materials.

Before solar power access to the Internet at affordable prices, the photovoltaic power industry has been developing under the support of policy subsidies from various countries, and the policy cycle has led to strong cyclicality of new photovoltaic installation.

Due to the high domestic production efficiency and low cost, the global polysilicon industry has a clear trend to transfer to China. The polysilicon industry has also gone through the process of enthusiastic investment, overcapacity, and elimination of mergers and acquisitions. The overall trend of silicon prices has been downward from more than ten years ago to now. Leading enterprises with cost advantages have slowly fled, and the concentration of the industry has increased.

German analyst Bernreuter’s latest report pointed out that “As solar energy becomes the cheapest energy source, the growth of global photovoltaic installed capacity in the next few years will exceed many expectations, which will drive the growth of demand for polysilicon.”

The photovoltaic industry chain can be roughly divided into three links: polysilicon, silicon wafer, midstream battery wafer, component, and downstream photovoltaic power generation system.

The technical route of photovoltaic power generation mainly includes crystalline silicon photovoltaic power generation and thin film photovoltaic power generation, among which crystal silicon photovoltaic power generation includes single crystal silicon wafer power generation and polysilicon wafer power generation. Both have their own advantages and disadvantages in cost and light energy conversion efficiency. The conversion efficiency of monocrystalline silicon is higher than that of polysilicon, but the production cost is also higher than that of polysilicon.

From the perspective of the composition of single and polycrystalline materials, the global supply of single crystal materials is about 330,000 tons, and the single crystal silicon wafer consumes about 324,000 tons of polysilicon, which is basically balanced between supply and demand. The global supply of polycrystalline ingots is 159,000 tons, and the polycrystalline silicon wafer consumes about 130,000 tons of polysilicon, which is slightly oversupply.

Polysilicon can be divided into industrial silicon, metallurgical polysilicon, solar polysilicon and electronic polysilicon according to the purity of products.

As the basic raw material for the manufacture of photovoltaic products, solar-grade polysilicon is located in the upstream link of the crystalline silicon photovoltaic industry. It has the characteristics of large production capacity investment amount, complex technology and technology, long production cycle, etc., and has high entry barriers and high added value in the industry. In the early stage of the outbreak of photovoltaic power stations, in order to rapidly expand the scale and meet the needs of power station construction, polysilicon occupied most of the market share.

At present, the supply side of the photovoltaic industry chain is mainly concentrated in mainland China, and the production capacity of polysilicon and silicon wafer links is obviously shifted to northwest and southwest China.

Polysilicon preparation mainly purified industrial silicon powder through a series of chemical means to obtain polysilicon materials that can be used in the solar energy industry and electronics industry.

For photovoltaic production, solar-grade polysilicon is generally between 6N and 9N. According to the specific parameter differences, the national standard divides solar-grade polysilicon into solar first-class, solar second-class and solar-class.

After melting ingots or drawing slices, polysilicon materials can be made into polysilicon wafers and monocrystalline silicon wafers respectively, and then used to make crystalline silicon batteries.

According to the statistics of China Photovoltaic Industry Association, 10 to 15 kilograms of silicon tetrachloride will be produced for every kg of polysilicon production. With the rapid development of the downstream photovoltaic industry of polysilicon, the annual output of polysilicon in China increased from 165,000 tons to 342,000 tons in 2015-2019, with a compound growth rate of 20%.

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It is expected that by 2025, China’s annual output of polysilicon will reach 1.022 million tons, and the by-product silicon tetrachloride will reach 10.22 million to 15.33 million tons. The adequacy of raw materials and the formation of industrial chain integration will effectively reduce the cost center of aerogel materials, and the substitution effect in the market is more obvious.

China’s polysilicon industry started relatively late compared with foreign countries. In 2007, the domestic construction projects reached 20,000 tons, which was the first year of large-scale production of polysilicon in China. In 2008, affected by the financial crisis, the United States and the European Union restricted the export of China’s photovoltaic products, and the price of polysilicon plummeted all the way.

In 2009, Guofa No. 38 listed polysilicon as an overcapacity industry, limiting the expansion of domestic polysilicon projects. Since then, with the recovery of the global economy, some European countries, such as Italy, have increased their support for photovoltaics, and the market demand for polysilicon has rebounded.

From 2013 to now, it is a leading global period. During this stage, China’s photovoltaic installation continues to expand, demand grows, and the competitiveness of polysilicon enterprises has increased. China’s polysilicon output ranks first in the world.

In 2018, the new production capacity in China reached 150,000 tons, the import volume decreased for the first time, the production layout of polysilicon was further optimized, gradually transferred to energy price depressions such as the northwest, and the production equipment was more advanced. In fact, this year can be regarded as the first year of substitution for polysilicon imports.

From the perspective of polysilicon production technology, according to the statistics of the Photovoltaic Association, the top ten polysilicon production enterprises in the world have adopted trichlorohydrosilicon improved Siemens method for polysilicon production.

In 1955, Siemens successfully developed the process technology of depositing silicon on the surface of hot silicon cores/silicon rods in a hydrogen atmosphere, and began industrial production in 1957, that is, the “Siemens method” polysilicon production process.

However, the conversion rate of Siemens polysilicon method is low, and the pollution of by-products such as silicon tetrachloride is serious. Therefore, an improved Siemens method with increased tail gas recovery and silicon tetrachloride hydrogenation process can be proposed.

In terms of raw materials, because the current production of polysilicon is mainly produced by hydrogen reduction of trichlorosilicon, the purity and quality of trichlorosilicon and hydrogen directly affect the quality of polysilicon. The mixing of oil, oxides or dust in production equipment will also seriously affect the crystalline shape of polysilicon, and the ratio and temperature control of reactants in the production process will also have a great impact on product quality.

The preparation process and mechanism make the manufacturing of polysilicon links biased towards fine chemical properties. Know-How technology is very different from the silicon wafers, battery wafers and component links biased towards physical properties in the middle and lower reaches.

Because downstream batteries are stocking up the next generation of N-type and HJT technologies, the requirements for polysilicon purity are getting higher and higher, which makes the technical barriers of the whole industry higher and higher for new entrants.

The whole polysilicon production process is relatively closed, which determines that its production cost is mainly affected by energy, raw material consumption and initial construction investment in the production process.

In the current mainstream polysilicon production method-improved Siemens method production cost, power cost, raw material cost and depreciation cost are the main part, which together account for about 80% of the total cost, of which power cost accounts for the largest proportion, accounting for 35%, silicon powder cost accounts for 30%, and depreciation cost accounts for 15%. Therefore, power, raw materials and depreciation have become the main areas to reduce the production cost of polysilicon.

In 2019, the average comprehensive power consumption of polysilicon nationwide has been reduced to 70kWh/kgSi. In the future, with the improvement of production equipment technology, system optimization ability, and production scale, it is expected that there will be more than 5% room for decline by 2025.

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