Monocrystalline silicon refers to the overall crystallization of silicon materials in the form of single crystals. It is a photovoltaic power generation material commonly used at present. Monocrystalline silicon solar cells are the most mature technology among silicon-based solar cells. Compared with polycrystalline silicon and amorphous silicon solar cells, their photoelectric The conversion efficiency is the highest. The production of high-efficiency monocrystalline silicon cells is based on high-quality monocrystalline silicon materials and mature processing techniques.
Monocrystalline silicon solar cells use monocrystalline silicon rods with a purity of up to 99.999% as raw materials, which also increases the cost and is difficult to use on a large scale. In order to save costs, the material requirements of the currently used monocrystalline silicon solar cells have been relaxed, and some of them use the head and tail materials processed by semiconductor devices and waste single crystal silicon materials, or make monocrystalline silicon for solar cells after complex drawing. Monocrystalline silicon wafer texturing technology is an effective means to reduce light loss and improve cell efficiency.
In order to reduce production costs, solar cells for ground applications use solar-grade monocrystalline silicon rods, and the material performance indicators have been relaxed. Some can also use the head and tail materials and waste single crystal silicon materials processed by semiconductor devices, and make single crystal silicon rods dedicated to solar cells after redrawing. Cut monocrystalline silicon rods into slices, generally about 0.3mm thick. Silicon wafers are processed into raw silicon wafers to be processed through processes such as polishing and cleaning.
To process solar cells, it is first necessary to dope and diffuse on the silicon wafer, and the general dopant is a trace amount of boron, phosphorus, antimony, etc. Diffusion is performed in a high temperature diffusion furnace made of quartz tubes. In this way, a P>N junction is formed on the silicon wafer. Then use the screen printing method, the finely prepared silver paste is printed on the silicon wafer to make the grid line, after sintering, the back electrode is made at the same time, and the anti-reflection source is coated on the surface with the grid line to prevent a large number of photons reflected off the smooth silicon wafer surface.
Thus, a monolithic sheet of a monocrystalline silicon solar cell is produced. After spot check and inspection, the single pieces can be assembled into solar cell modules (solar cell panels) according to the required specifications, and a certain output voltage and current can be formed by connecting in series and in parallel. Finally, it is encapsulated with the frame and materials. According to the system design, the user can form solar cell modules into solar cell square arrays of various sizes, also known as solar cell arrays. The photoelectric conversion efficiency of monocrystalline silicon solar cells is about 15%, and the laboratory results are more than 20%.