Because of the different pre-production technology of monocrystalline silicon cell sheet and polycrystalline silicon cell sheet, there are some differences between them from appearance to electrical properties. From the appearance: the four corners of the monocrystalline silicon cell are arc shaped, no surface pattern; The four corners of the polycrystalline silicon cell are square, and the surface has a pattern similar to ice flowers.
To the user, there is not much difference between a monocrystalline silicon cell and a polycrystalline silicon cell. Monocrystalline silicon cells and polycrystalline silicon cells have good life and stability. Although the average conversion efficiency of monocrystalline cells better than the average conversion efficiency of polysilicon batteries around l %, but because of monocrystalline silicon solar cell can only be made quasi square (the four Angle is arc), when the solar battery components are part of an area of fill, and polycrystalline silicon solar cell is a square, there is no this problem, So it's almost the same for the efficiency of the solar cell components. In addition, due to the manufacturing process of two kinds of solar cell materials, polycrystalline silicon solar cell manufacturing process consumes less energy than monocrystalline silicon solar cell is about 30%, so the polycrystalline silicon solar cells account for a growing share of the total global solar cell production, the manufacturing cost will be much smaller than that of single crystal silicon cell, So using polysilicon solar cells will be more energy efficient and environmentally friendly.
9. The concept of inverter
Inverter is for rectification, the rectifier to convert AC electric energy into DC electric energy process called rectification. So the process of DC energy into AC energy is called the inverter, the completion of the inverter function of the circuit called the inverter circuit, the realization of the inverter process device called the inverter.
Why must the photovoltaic inverter be used in the solar photovoltaic power generation system? At present, the power generation system in our country is mainly a DC system, which is to charge battery with the electricity produced by the solar cells, and supply power to the battery directly. As the solar lighting system which is widely used in the northwest of our country and the microwave station power supply system are all DC system. This kind of system has simple structure and low cost, but it is difficult to realize the standardization and compatibility of the system due to the different DC voltages of the load (such as 12V, 24V, 48V, etc.). Especially household appliances, such as fluorescent lamps, television sets, refrigerators, electric fans and most power machinery are the use of alternating current work, that is, most of the AC load, so the use of DC power supply of photovoltaic power, it is difficult to enter the market as a commodity. The purpose of setting inverter in solar photovoltaic system is to convert direct current to alternating current, which is convenient to meet the needs of most users.
In addition, if the power line is damaged or forced to shut down, the inverter stops supplying power to the electrical equipment or grid. If the power line voltage is low or undervoltage, or there is a large disturbance, use a sensor for "non-island" inverter to sense this situation. When this happens, the inverter will automatically turn off its power supply to the grid or transmit it elsewhere, preventing it from becoming an "island" of electricity generation. The so-called island effect means that the grid-connected photovoltaic power generation system connected in parallel to the grid can still work and operate independently after the grid fails.