Polysilicon

Why in News?

The Government of India is working to add around 30 GW of polysilicon manufacturing capacity by 2030 and is also working on a subsidy scheme to support domestic polysilicon production.

About Polysilicon

Polysilicon, also known as polycrystalline silicon or poly-Si, is a highly purified form of silicon composed of multiple small silicon crystals or grains.

Unlike monocrystalline silicon, which consists of a single continuous crystal structure, polysilicon contains several smaller crystals fused together in a relatively haphazard arrangement.

Polysilicon is highly pure and can generate almost as much energy as pure monocrystalline silicon, making it an important material for the solar energy industry.

Importance in Solar Energy

Polysilicon is a crucial raw material in the production of solar cells and solar modules. It forms an important link in the solar photovoltaic manufacturing chain.

To produce solar modules, polysilicon is melted at high temperatures to form ingots. These ingots are then sliced into thin wafers, which are further processed into solar cells and solar modules.

Thus, the basic manufacturing sequence can be understood as:

Polysilicon → Ingots → Wafers → Solar Cells → Solar Modules

Production of Polysilicon

Polysilicon is produced by purifying metallurgical-grade silicon into a high-purity form suitable for applications in solar cells and electronics.

There are two major technologies used for producing high-quality polysilicon for solar-cell manufacturing: the Siemens process and Fluidized Bed Reactor (FBR) technology.

Siemens Process

The Siemens process is a major conventional method for producing high-purity polysilicon. It involves depositing purified silicon onto heated silicon rods under controlled conditions.

Fluidized Bed Reactor (FBR) Technology

FBR technology is another method for producing high-purity polysilicon. It uses a fluidized bed reactor to continuously deposit silicon particles, offering a different production approach from the conventional Siemens process.

Use in the Semiconductor Industry

Apart from solar photovoltaics, polysilicon is also important in the semiconductor industry. It is used in the manufacture of integrated circuits and other electronic components.

Therefore, polysilicon is strategically important for both renewable energy manufacturing and the electronics and semiconductor sector.

Global Production

Global production of solar-grade polysilicon is highly concentrated. China accounts for the large majority of global solar-grade polysilicon output, making the material an important component of global solar supply-chain security.

Importance for India

The proposed addition of 30 GW of polysilicon manufacturing capacity by 2030 is significant for strengthening India's domestic solar manufacturing ecosystem.

Developing domestic polysilicon production can help India build a more integrated solar photovoltaic supply chain, reduce dependence on concentrated global sources and support the country's broader expansion of renewable energy manufacturing.