Crystal silicon solar cell manufacturing process flow Crystal silicon solar cell manufacturing process description is as follows: (1) Slicing: The multi-wire cutting is used to cut a silicon rod into a square silicon wafer. (2) Cleaning: Use a conventional silicon wafer cleaning method and then remove the 30-50 μm surface damage layer from the silicon wafer with an acid (or antimony) solution. (3) Preparation of suede: Anisotropic etching of silicon wafers using a niobium solution prepares suede on the surface of the silicon wafer. (4) Phosphorus diffusion: Diffusion is performed using a coating source (or a liquid source, or a solid phosphazene source) to make a PN+ junction. The junction depth is generally 0.3-0.5 um. (5) Peripheral etching: When the diffusion layer is formed on the peripheral surface of the silicon wafer during diffusion, the upper and lower electrodes of the battery may be short-circuited, and the peripheral diffusion layer may be removed by masking wet etching or plasma dry etching. (6) Remove the back PN+ junction. Commonly used wet etching or grinding method to remove the back PN + knot. (7) Production of upper and lower electrodes: Processes such as vacuum evaporation, electroless nickel plating or aluminum paste printing and sintering. First make the lower electrode and then make the upper electrode. Aluminum paste printing is a widely used process. (8) Production of anti-reflection film: In order to reduce the reflection loss, an anti-reflection film should be covered on the surface of the silicon wafer. The anti-reflection film is made of MgF2, SiO2, Al2O3, SiO, Si3N4, TiO2, Ta2O5, etc. Process methods may be vacuum coating, ion plating, sputtering, printing, PECVD, or spraying. (9) Sintering: The battery chip is sintered on the bottom plate of nickel or copper. (10) Test bins: According to the specified parameters, test classification. It can be seen that the manufacturing method of solar cell chips is basically the same as that of semiconductor devices, and the production process equipment is also basically the same, but the processing precision is far lower than the manufacturing requirements of integrated circuit chips, which provides the scale production of solar cells. The favorable conditions. The difference between monocrystalline silicon and polysilicon The difference between monocrystalline silicon and polysilicon is that when the molten silicon is solidified, the silicon atoms are arranged in a diamond crystal lattice into a plurality of crystal nuclei, and if these crystal nuclei grow into chips having the same crystal plane orientation, single crystal silicon is formed. If these crystal nuclei grow into chips with different crystal orientations, polysilicon is formed. The difference between polysilicon and monocrystalline silicon is mainly manifested in the physical properties. For example, in terms of mechanical properties, electrical properties, etc., polysilicon is not as good as monocrystalline silicon. Polysilicon can be used as a raw material for drawing monocrystalline silicon. Monocrystalline silicon can be regarded as the purest substance in the world. General semiconductor devices require silicon purity of more than six. The requirements for large-scale integrated circuits are higher, and the purity of silicon must reach nine nines. At present, people have been able to produce single crystal silicon with a purity of twelve nines. Monocrystalline silicon is an indispensable basic material in modern science and technology such as electronic computers and automatic control systems. High-purity silicon is extracted in quartz. For example, monocrystalline silicon is extracted through the following process: quartz sand, metallurgical grade silicon, purified and refined, deposited polycrystalline silicon ingot, monocrystalline silicon, and silicon wafer. The refining of metallurgical grade silicon is not difficult. Its preparation is mainly made by reducing quartz sand with carbon in an electric arc furnace. The purity of the silicon thus recovered is about 98-99%, but the silicon used in the semiconductor industry must also be highly purified (the purity of the electronic grade polysilicon requires 11 9 and the solar cell grade only requires 6 9). In the purification process, a key technology of “trichlorosilane reduction method (Siemens method)†has not yet been mastered in China. Without this technology, more than 70% of the polysilicon in the refining process in China is emitted through chlorine. Not only the refining costs are high, but the environmental pollution is very serious. Every year, China extracts a large amount of industrial silicon from quartz stones and exports them to countries such as Germany, the United States, and Japan at a price of US$1/kg. These countries process industrial silicon into high-purity crystalline silicon materials for US$46-80. / Kilogram price sold to our solar energy companies. After high-purity polycrystalline silicon is obtained, it is smelted in a single crystal furnace into single-crystal silicon, which is then sliced ​​and then used for manufacturing of integrated circuits. The difference between monocrystalline silicon and polycrystalline silicon cells Due to the different production processes of single-crystal silicon cells and polycrystalline silicon cells, they have some differences in appearance and electrical properties. From the appearance point of view, the four corners of the monocrystalline silicon cell are arc-shaped, and the surface has no pattern; the four corners of the polycrystalline silicon cell are square corners, and the surface has the similar ice pattern. For the user, there is not much difference between a single crystal silicon battery and a polycrystalline silicon battery. Monocrystalline silicon cells and polycrystalline silicon cells have good life and stability. Although the average conversion efficiency of a monocrystalline silicon cell is about 1 percent higher than the average conversion efficiency of a polycrystalline silicon cell, since a monocrystalline silicon solar cell can only be made into a quasi-square (its four corners are arcs), when a solar cell element is formed There is a part of the area filled with dissatisfaction, and polysilicon solar cells are square, this problem does not exist, so the efficiency of solar cell components is almost the same. In addition, because the manufacturing process of two kinds of solar cell materials is different, the energy consumed in the manufacturing process of polycrystalline silicon solar cells is about 30% less than that of monocrystalline silicon solar cells, so the share of polycrystalline silicon solar cells in the total output of global solar cells is getting more and more. Large, manufacturing costs will also be much smaller than monocrystalline silicon cells, so using polycrystalline silicon solar cells will be more energy-efficient and environmentally friendly. Inverter concept The inversion is for rectification, and the process of converting the AC power into DC power by the rectifier is called rectification. The process of transforming DC power into AC power is called inverting. The circuit that completes the inverter function is called an inverter circuit, and the device that implements the inverter process is called an inverter. Why do we have to use photovoltaic inverters in solar photovoltaic power generation systems? At present, China's power generation system is mainly a direct current system, that is, the electricity generated by solar cells is used to charge the batteries, and the batteries directly supply power to the loads, such as the use of more places in northwest China. The solar lighting system and the microwave station power supply system far from the grid are DC systems. Such a system is simple in structure and low in cost, but due to the difference in the DC voltage of the load (such as 12v, 24v, 48V, etc.), it is difficult to achieve system standardization and compatibility. In particular, household appliances such as fluorescent lamps, televisions, refrigerators, electric fans, and most of the power machinery work with AC power, that is, most of them are AC loads. Therefore, photovoltaic power supplies powered by DC power are difficult to enter as markets for commodities. . The purpose of setting up an inverter in a solar photovoltaic system is to convert direct current into alternating current, which is convenient for most users' loads. In addition, if the power line is damaged or forced to shut down, the inverter must stop supplying power to the power device or the power grid. If the power line voltage is low or undervoltage, or if there is a large disturbance, a sensor for the "non-islanding" inverter is used to sense this condition. When this happens, the inverter will automatically turn off the power supply to the grid or transfer the power to other places, thereby preventing it from becoming an "island" of electric power generation. The so-called islanding effect, that is, after the grid fails, the photovoltaic grid-connected power generation system connected in parallel on the grid can still work and is in an independent operation state. Haematocrit Determination Machine,Haematocrit Determination Equipment,Haematocrit Determination instrument Topscien Instrument(Ningbo China)Co.,LTD , https://www.centrifugesupply.com
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