Monocrystalline solar panels tend to be more efficient than polycrystalline solar panels. Their efficiency rating is around 19%-20% because the solar cells have high purity. These solar panels are the best solar panels with the best purity and highest efficiency levels. Monocrystalline solar panels are also called single crystalline silicon solar panels. Because these solar panels are made of a single piece of silicon crystal. These silicon crystals are cylindrical in shape. The silicon used to make these solar panels are high in purity. To increase the efficiency and maintain the cost, the solar cells are cut off from all its edges. Monocrystalline solar panels are also known for their dark black hue on their surface.