To make polycrystalline cells, molten silicon is poured into a cast in which it cools and solidifies. The front surface of the cells is lined with mm‐sized pyramidal structures (textured surface) to reduce reflection loss of incident light. An anti‐reflection coating (ARC) made of titanium oxide (TiOx) or silicon nitride (SiNx) is coated on the textured silicon surface to further reduce the loss of reflection. Then the rectangular blocks of silicon are cut into 156 mm (6 inches) or 125 mm (5 inches) square cells which are arranged neatly on a rectangular sheet of glass. They cells are blue in color.
Advantages of Polycrystalline solar panels
- The process of making polycrystalline silicon solar cells is simple and cost less. The amount of waste silicon generated is less compared to monocrystalline. The cost for solar cell includes the cost of the silicon (50%), cell processing (20%) and module processing (30%).
- Polycrystalline solar cells have lower heat tolerance than monocrystalline cells. Polycrystalline solar panels have a higher temperature co-efficient than mono cells due to which it generates less heat and more electricity than its mono counterpart. One meter square of polycrystalline solar cells generates around 180W
Disadvantages of Polycrystalline solar panels
- The efficiency of polycrystalline solar cells is around 14-16%. Because of the use of lower silicon purity, polycrystalline solar cells are not that efficient.
- Lower space-efficiency- larger space is needed by polycrystalline solar cells to produce the same amount of output than monocrystalline cells
Major manufacturers of these cells are Hanwha, Kyocera, Hyundai, Trina, and Solar World.
Latest news- In November 2015 Trina Solar declared that it had produced a poly crystalline cell with efficiency of 21.25%, which would allow them to produce the cells efficiencies between 18-20% ,something which seemed impossible in 2013.