What is Polycrystalline Silicon?
Polycrystalline silicon, also sometimes called multicrystalline silicon, polysilicon, or poly-Si, is a high grade and high purity form of silicon that is used in many high technology applications – most notably as one of the main components in solar photovoltaic cell manufacturing.
Key Takeaways:
- Polycrystalline silicon is also called multicrystalline silicon, polysilicon, or poly-Si
- Polycrystalline silicon is produced from lesser grade silicon by a chemical purification process, called the Siemens process
- Polycrystalline silicon appears to have large ‘flecks’ or crystals known as crystallites that give polycrystalline silicon a very distinctive appearance
Understanding Polycrystalline Silicon
Polycrystalline silicon, also sometimes called multicrystalline silicon, polysilicon, or poly-Si, is a high grade and high purity form of silicon that is used in many high technology applications – most notably as one of the main components in solar photovoltaic cell manufacturing.
Polycrystalline silicon is produced from lesser grade silicon by a chemical purification process, called the Siemens process, which involves the distillation of various silicon compounds at very high temperatures. When the resulting polycrystalline silicon is produced for the electronics industry the impurity levels are less than one part per billion, while solar grade silicon is generally slightly less pure.
To the naked eye, polycrystalline silicon appears to have large ‘flecks’ or crystals known as crystallites that give polycrystalline silicon a very distinctive appearance. When used in solar applications, polycrystalline silicon photovoltaic cells are the most common type of solar cell due to their lower cost than monocrystalline silicon. Between 2008 and 2013 the total number of solar manufacturers producing polycrystalline silicon photovoltaic cells increased by more than ten times.
About 5 tons of polycrystalline silicon is required to manufacture 1 megawatt of standard solar modules.
Related Terms
Solar-Grade Silicon – Solar grade silicon is a form of high-purity silicon (99.9999% pure) that is produced exclusively for the solar industry and does not typically include semiconductor-grade silicon.
N-type Silicon – Silicon that has been chemically bonded with phosphorus gas to create an electrically conductive, negatively charged, form of silicon.
Photovoltaic Cell – A photovoltaic cell is a device that converts solar energy into direct current electricity for use in homes or businesses through the photovoltaic effect.