There are two main types of solar panel:
Polycrystalline solar panels are made from the fragments of silicon that are melted together to form wafers. They are less expensive comparatively and have about 18% efficiency.
Monocrystalline solar panels are made from silicon bars and cut into wafers. They have a diamond pattern. They are more expensive comparatively. Monocrystalline solar panels have the efficiency of 20%