Polycrystalline solar cells, often called multi-crystalline panels, are highly cost-effective, budget-friendly, and durable photovoltaic devices made by melting multiple silicon fragments together.OverviewPolycrystalline silicon, or multicrystalline silicon, also called polysilicon, poly-Si, or mc-Si, is a high purity, form of, used as a raw material by the solar and. Polysilicon. In single-crystal silicon, also known as, the crystalline framework is homogeneous, which can be recognized by an even external colouring. The entire sample is one single, continuous and unbrok.