An amorphous solar cell is a type of solar cell that is relatively cheap to produce and widely available. They are named because of their composition at the microscopic scale. In this solar cell, the silicon material that makes up the cell is not highly structured or crystallized. Amorphous solar cells are usually created by applying doped silicon material to the back of a plate of glass. The cells usually appear dark brown on the sun-facing side and silvery on the conductive side. When produced as a solar panel it will appear to have several thin parallel lines running across its surface. The solar panels usually come without any obvious hook-up points or wires. They also have relatively high output impedance.