1. What is a solar cell?
A: Solar cells are semiconductor devices that convert solar radiation directly into electrical energy based on the photovoltaic effect of semiconductors.
Commercially available solar cells are mainly of the following types: monocrystalline silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells, and currently there are Cadmium tellurium cells, copper indium selenide cells, and nano titanium oxide sensitized cells etc.
Crystalline silicon (single crystal, polycrystalline) solar cells require high purity silicon raw materials, generally requiring a purity of at least 99.99998%, that is, up to 2 impurity atoms are allowed in 10 million silicon atoms. The silicon material is obtained by using silicon dioxide (SiO2) as a raw material, melting it and removing impurities to obtain coarse silicon. From silicon dioxide to solar cell wafers, involving a variety of production processes and processes, generally divided into: silica -> metallurgical grade silicon -> high purity trichlorosilane -> high purity polysilicon -> single crystal silicon rod or Polycrystalline silicon ingots -> silicon wafers -> solar cells.
2. What is a monocrystalline silicon solar panel (or PV module)?
Monocrystalline silicon solar cells are mainly made of single crystal silicon. Compared with other types of solar cells, single crystal silicon cells have the highest conversion efficiency. In the early days, monocrystalline silicon solar cells occupied the majority of the market, and after reclaiming polysilicon in 1998, the market share occupied the second. Since the efficiency of monocrystalline silicon has been greatly improved in recent years, and the cost has decreased compared with the previous one, the market share of monocrystalline silicon has risen again, and the cells seen on the market now have mostly monocrystalline silicon. The silicon crystal of the monocrystalline silicon solar cell is perfect, its optical, electrical and mechanical properties are very uniform, and the color of the solar cell is mostly black or dark, which is especially suitable for cutting into small pieces to make small consumer products. The conversion efficiency of the single crystal silicon cell is 19%-23%. Generally, the four corners of a monocrystalline silicon solar cell have a nearly round chamfer. The thickness of monocrystalline silicon solar cells is generally 180uM thick. The current production trend is toward ultra-thin and high efficiency.
3. What is a polycrystalline silicon solar panel (or PV module)?
In the production of polycrystalline silicon solar cells, high-purity silicon as a raw material is not purified into a single crystal, but melt-cast into a square silicon ingot, which is then sliced and processed similarly to process single crystal silicon. Polycrystalline silicon is easily identified from its surface. The silicon wafer is composed of a large number of crystal regions of different sizes (the crystal is crystallized on the surface). The generator is made of the same crystal as the single crystal, but the silicon wafer is composed of a plurality of crystals of different sizes and orientations. In the grain group, the photoelectric conversion at the grain boundary is easily disturbed, so the conversion efficiency of polycrystalline silicon is relatively low. At the same time, the optical, electrical properties and mechanical properties of polycrystalline silicon are not as good as monocrystalline silicon solar cells. The conversion efficiency of polycrystalline silicon solar cells is 18%-20%. The polycrystalline silicon solar cells are square pieces, which have the highest filling rate when manufacturing solar modules, and the products are relatively beautiful. The thickness of polycrystalline silicon solar cells is generally 180 uM thick, and is thinner, and more expensive silicon materials are saved.
4. How to distinguish between monocrystalline silicon solar cell and polycrystalline silicon solar cell?
Polycrystalline solar cell are square or rectangular at right angles, and the four corners of a monocrystalline solar cell have chamfers that are nearly circular.