Photovoltaic Silicon Wafers

Photovoltaic silicon wafer is an important material for preparing photovoltaic crystalline silicon cells. It is located in the middle reaches of the photovoltaic industry chain. The upstream is silicon material, which accounts for about 86% of the cost of silicon wafers; the downstream is cells, and silicon wafers account for about 86% of the cost of cells. 62%.

 

Photovoltaic silicon wafers can be divided into monocrystalline silicon wafers and polycrystalline silicon wafers according to different raw materials and processes. Monocrystalline silicon rods are mainly produced using the Czochralski method, while polycrystalline silicon ingots are mainly produced using the ingot casting method.

 

Currently, monocrystalline silicon wafers (P type + N type) account for about 95% of the market and have become the mainstream of the industry.

 

2.1 Crystal pulling link: Czochralski method is the mainstream preparation process

 

According to different crystal growth methods, single crystal silicon preparation technology can be divided into Czochralski method and zone melting method. The Czochralski method is mainly used in the photovoltaic field.

 

The zone melting method has more stringent requirements on raw materials, equipment and technology, produces smaller crystals, and has higher production costs. It is mainly used in the semiconductor field.

 

2.2 Processing link: slicing is the core process

 

After the silicon rod is pulled out in a single crystal furnace, it needs to go through four processes of cutting, squaring, grinding, and slicing to form a single crystal silicon wafer.

 

Slicing is the core processing link, and advances in diamond wire technology help silicon wafers become thinner.

 

3. Supply side: China’s production capacity dominates

 

Domestic silicon wafer production accounts for 97.4% of the world, taking an absolute leading position. In 2022, the nominal production capacity of domestic silicon wafer companies is 677GW, and they plan to expand production capacity by 370GW. The nominal production capacity is relatively excess, but the high-end production capacity level is low.

 

Longi Green Energy and TCL Zhonghuan account for more than 50% of the production capacity, and the duopoly pattern is still significant. Top 10 domestic companies in terms of production capacity in 2021: Longi Green Energy, TCL Zhonghuan, JinkoSolar, JA Solar, Shanghai Machinery CNC, Jingyuntong, Shuangliang Energy Saving.

 

 

4. Development trends: large size, N-type technology and thinning

 

Using the same materials, increasing the size of silicon wafers can effectively reduce the number of crystal pulling and slicing, thereby effectively reducing unit production costs; in addition, large-size silicon wafers provide the possibility of exploring higher efficiency for components.

 

In June 2020, seven companies including Longi, Jinko, and JA Solar jointly advocated the establishment of the M10 (182mm) photovoltaic silicon wafer standard. While 182-size silicon wafers are larger in size, they also have advantages over 210-size silicon wafers in terms of packaging, transportation, manual installation, and load capacity. They have now become the mainstream choice for downstream manufacturers.

 

In the future, N-type batteries will replace P-type batteries and become the mainstream, and the demand for N-type silicon wafers will benefit simultaneously.

 

Under the same area, making silicon wafers thinner can effectively reduce the silicon consumption of a single wafer. Thinning has become one of the main ways to reduce costs in the silicon wafer process.