Polycrystalline solar cells are made by heating the silicon from multiple crystals of silicon and pouring the molten silicon into a mold. The resultant square cells are soldered together and sealed under glass to make panels that are about one meter squared.
With a lower return electricity rate of 12-14%, polycrystalline silicon panels are not as efficient as monocrystalline panels. But the square shape of the polycrystalline solar cell ensures less space is wasted on the module itself. Often, this space gain makes up for lower efficiency, keeping the power per given area comparable to monocrystalline modules.
Cost and Durability
The production process allows the quality of silicon for polycrystalline cells to be lower than for monocrystalline cells, and the cost of polycrystalline cells is correspondingly lower. A polycrystalline panel is optimally placed on a south-facing roof with minimal shade coverage. As the production process of polycrystalline panels is similar to that of monocrystalline panels, the durability is parallel. Crystalline panels typically have a warranty of 25 years, so the initial cost will likely be recouped.