What are monocrystalline, polycrystalline and amorphous cells?

The terms monocrystalline, polycrystalline and amorphous describe the nature of the silicon used to make the PV cell. Monocrystalline cells use a wafer of single crystal silicon, typically cut from a larger ingot of single crystal silicon. Monocrystalline cells are uniform in appearance. Polycrystalline cells use multi-crystalline silicon, this is cheaper to produce but slightly less efficient. A patchwork of individual crystals can be clearly seen in a polycrystalline cell. Amorphous cells have no crystalline structure and are the least efficient of the three technologies.