Solar/Photovoltaic Power

Most commercial PV cells are made from silicon, and come in three general types: monocrystalline, multicrystalline, and amorphous.

1.       Single crystal or Monocrystalline cells are made using silicon wafers cut from a single, cylindrical crystal of silicon. This type of PV cell is the most efficient, with approximately 15% efficiency (defined as the fraction of the sun’s energy that is converted to electrical power), but is also one of the most expensive to produce. 

2.       Multicrystalline or Polycrystalline silicon cells are made by casting molten silicon into ingots, which crystallize into a solid block of intergrown crystals. The size of the crystals is determined mostly by the rate at which the ingot is cooled, with larger grains made by slower cooling. Cells are then cut from the ingot. Multicrystalline cells are less expensive to produce than monocrystalline ones, due to the simpler manufacturing process and lower purity requirements for the starting material. However, they are slightly less efficient, with average efficiencies of around 12%.

3.       Amorphous silicon PV cells are made from a thin layer of noncrystalline silicon placed on a rigid or flexible substrate. They are relatively easy to manufacture and are less expensive than monocrystalline and polycrystalline PV, but are less efficient with efficiencies of around 6%. Their low cost makes them the best choice where high efficiency and space are not important.