Polycrystalline silicon or Polysilicon( poly-Si or “poly”) is a material consisting of multiple small silicon crystals.The difference between Silicon Metal and Polysilicon is that Poly is highly pure form of silicon and is much costlier.Polycrystalline silicon can be as much as 99.9999% pure (also known as 4N pure,the 4 denotes the number of 9s after the decimal point).Polysilicon was primarily used by the semi industry till 5-6 years ago and the electronic industry used 9N pure polysilicon.The Solar Industry which has become the main user of polysilicon nowadays can do with 6N pure poly.

Polysilicon is refined to single crystal polysilicon before it can be used by the semiconductor industry.However solar cells can be made even from multicrystalline polysilicon.Monocrystalline solar cells on the other hand are made of single crystal polysilicon and have higher efficiency than those made from multicrystalline polysilicon.Polycrystalline cells can be recognized by a visible grain, a “metal flake effect”. Semiconductor grade (also solar grade) polycrystalline silicon is converted to “single crystal” silicon – meaning that the randomly associated crystallites of silicon in “polycrystalline silicon” are converted to a large “single” crystal.