What is the difference between monocrystalline and polysilicon solar cells?
Monocrystalline silicon solar cells mainly use monocrystalline silicon to manufacture, compared with other kinds of solar cells, monocrystalline silicon cells have the highest conversion efficiency. In the early stage, monocrystalline silicon solar cells occupied the majority of the market share, and only after 1998, the market share of polysilicon occupied the second place. Due to the shortage of polysilicon raw materials in recent years, after 2004, the market share of monocrystalline silicon has risen slightly, and now monocrystalline silicon is in the majority of batteries on the market.
The silicon crystals of monocrystalline silicon solar cells are very perfect, and their optical, electrical and mechanical properties are very uniform. The color of the cells is mostly black or dark, which is especially suitable for cutting into small pieces to make small consumer products. The conversion efficiency of monocrystalline silicon cells achieved in the laboratory is 24.7%. The conversion efficiency of commercial cells is 10% to 18%. Monocrystalline silicon solar cell because of production process problems, generally, its semi-formed silicon ingot is cylindrical, and then through slicing – cleaning – diffusion making – removal of the back pole – making electrode – corrosion around – evaporation coating anti-reflection film and other processes into finished products.
Generally, the four corners of monocrystalline silicon solar cells are rounded. The thickness of the single crystal silicon solar cell is commonly 200 um to 350 um thick, now production trend is to develop in the direction of ultra-thin and efficient in the production of polysilicon solar cell, as raw materials of high purity silicon is not again purification into a single crystal, but melting cast into a square silicon ingot, then processing single crystal silicon slice and similar work.
Polysilicon from its surface is easy to recognize, silicon is composed of a large number of different sizes of crystallization area (surface crystal crystal), the generating mechanism and single crystal are the same, but because of the silicon wafer by multiple grain group in different size, different orientation, the grain interface photoelectric conversion are susceptible to interference, thus polysilicon conversion rate is relatively low, at the same time, The consistency of optical, electrical and mechanical properties of polysilicon is not as good as that of monocrystalline silicon solar cells.
The highest laboratory efficiency of polysilicon solar cells reaches 20.3%, and the commercial efficiency is generally 10%-16%. Polysilicon solar cells are square pieces, which have the highest filling rate when making solar modules, and the products are relatively beautiful. The thickness of polycrystalline silicon solar cells is generally 220uM-300uM thick, some manufacturers have produced 180uM thick solar cells, and to thin development, more to save expensive silicon materials. A polychip is a square or rectangle with right angles. The four corners of a single crystal have nearly circular chamfering. A single crystal with a money-shaped hole in the middle of a component can be seen at a glance
1. Monocrystalline silicon solar cells
At present, the photoelectric conversion efficiency of monocrystalline silicon solar cells is about 15%, and the highest reaches 24%, which is the highest in all kinds of solar cells at present. However, the production cost is so high that it cannot be widely and widely used. Because monocrystalline silicon is usually sealed with toughened glass and waterproof resin, it is durable and has a service life of up to 15 years and up to 25 years.
2, polysilicon solar cells
The production process of polycrystalline silicon solar cell is similar to that of monocrystalline silicon solar cell, but the photoelectric conversion efficiency of polycrystalline silicon solar cell is much lower, its photoelectric conversion efficiency is about 12% (The world’s highest efficiency polycrystalline silicon solar cell with 14.8% efficiency launched by Sharp in Japan on July 1, 2004).
In terms of production cost, it is cheaper than monocrystalline silicon solar cells, the material is simple to manufacture, saves power consumption, and the total production cost is low, so it has been developed in large quantities. In addition, the service life of polysilicon solar cells is shorter than that of monocrystalline solar cells. In terms of performance-price ratio, monocrystalline silicon solar cells are slightly better.