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Monocrystalline silicon and Polysilicon solar cell
|Monocrystalline silicon solar cell
Monocrystalline silicon solar cell is currently the fastest developed solar cell. Its composition and production technology have been stereotyped, and products have been widely used in space and ground facilities. The solar cell is made of high purity monocrystalline silicon rods, with a purity of 99.9999%. In order to reduce the cost of production, solar cells such as solar cells used on the ground are now using single crystal silicon rods, and the performance of materials is relaxed. Some can also be processed by semiconductor devices and the waste monocrystalline silicon material, through the recovery of a single crystal silicon rod for solar cells. The monocrystalline silicon rod is cut into pieces, which is about 0.3 millimeters thick. Silicon wafers are made by forming, polishing and cleaning.
Polysilicon solar cell
Monocrystalline silicon solar cell production requires a large number of high purity silicon materials, these materials and manufacturing process complexity, large power consumption, the total cost of solar cell production is over 1/2, and drawn the monocrystalline silicon cylindrical section making solar cells and solar modules composed of planar wafer, low utilization rate. Therefore, since 80s, some European and American countries have invested in the development of polysilicon solar cells.
At present, polycrystalline silicon materials used for solar cells are mostly aggregates containing a large number of single crystal particles, or they are melted and cast by waste single crystal silicon and metallurgical grade silicon materials. The process is the choice of resistivity is 100 ~ 300 ohm cm polycrystalline or single crystal silicon bulk head materials, crushing, proper corrosion with 1:5 mixture of hydrofluoric acid and nitric acid, then rinse with deionized water is neutral, and drying. Use a quartz crucible to install a lot of silicon material, add a proper amount of borosilicate, put the casting furnace, and heat and melt in the vacuum state. After melting, it should be kept warm for about 20 minutes, and then injected into the graphite mold, and the polycrystalline silicon ingot will be obtained after slowly solidifying and cooling. The silicon ingot can be cast into a cube, so that the slice is processed into a square solar cell piece, which can improve the utilization of material and facilitate the assembly.