Principle of solar power battery
The sun shines on the semiconductor p-n junction, forming a new hole electron pair. Under the effect of the built-in electric field of the p-n junction, the photogenerated holes flow to the p area, and the photogenerated electrons flow to the n area. After the circuit is connected, current is generated. This is the working principle of photoelectric effect solar power batterys.
There are two ways of solar power generation, one is light heat electricity conversion, the other is light electricity direct conversion.
Optical thermal electrical conversion
The light heat electricity conversion mode uses the heat energy generated by solar radiation to generate electricity. Generally, the solar collector converts the absorbed heat energy into steam of working medium, and then drives the steam turbine to generate electricity. The former process is light heat conversion process; The latter process is the thermal electric conversion process, which is the same as the ordinary thermal power generation. The disadvantage of solar thermal power generation is its low efficiency and high cost. It is estimated that its investment is at least 5-10 times more expensive than that of ordinary thermal power plants. A 1000MW solar thermal power station requires an investment of 2 to 2.5 billion dollars, with an average investment of 1 kW of 2000 to 2500 dollars. Therefore, it can only be applied to special occasions on a small scale, while large-scale utilization is not economical and can not compete with ordinary thermal power plants or nuclear power plants.
Optical electric direct conversion
solar power battery power generation is based on the photoelectric properties of specific materials. Blackbodies (such as the sun) radiate electromagnetic waves of different wavelengths (corresponding to different frequencies), such as infrared, ultraviolet, visible light, and so on. When these rays irradiate on different conductors or semiconductors, photons interact with free electrons in the conductors or semiconductors to generate current. The shorter the wavelength and the higher the frequency of the ray, the higher the energy. For example, the energy of ultraviolet ray is much higher than that of infrared ray. However, not all wavelengths of ray energy can be converted into electrical energy. It is worth noting that the photovoltaic effect is independent of the intensity of the ray. Only when the frequency reaches or exceeds the threshold value that can produce photovoltaic effect can the current be generated. The maximum wavelength of the light that can make the semiconductor produce photovoltaic effect is related to the band gap width of the semiconductor. For example, the band gap width of crystal silicon is about 1.155eV at room temperature. Therefore, only light with a wavelength less than 1100nm can make the crystal silicon produce photovoltaic effect. solar power battery power generation is a renewable and environment-friendly power generation method, which will not produce carbon dioxide and other greenhouse gases in the power generation process, and will not pollute the environment. It can be divided into silicon based semiconductor battery, CdTe film battery, CIGS film battery, dye sensitized film battery, organic material battery, etc. according to the production materials. Among them, silicon cells are divided into single crystal cells, polycrystalline cells and amorphous silicon thin film cells. The most important parameter for solar power batterys is the conversion efficiency. Among the silicon based solar power batterys developed in the laboratory, the efficiency of monocrystalline silicon cells is 25.0%, that of polycrystalline silicon cells is 20.4%, that of CIGS thin film cells is 19.6%, that of CdTe thin film cells is 16.7%, and that of amorphous silicon (amorphous silicon) thin film cells is 10.1%
solar power battery is a kind of photoelectric element that can convert energy. Its basic structure is made of P type and N type semiconductors. The most basic material of semiconductor is "silicon", which is non-conductive. However, if different impurities are doped into the semiconductor, it can be made into P-type and N-type semiconductors. Then P-type semiconductors have a hole (P-type semiconductors have one less electron with negative charge, which can be regarded as one more positive charge), and N-type semiconductors have one more free electron potential difference to generate current, so when the sun shines, The light energy excites the electrons in silicon atom and generates convection of electrons and holes. These electrons and holes will be affected by the built-in potential, attracted by N-type and P-type semiconductors respectively, and gathered at both ends. At this time, if the external parts are connected with electrodes to form a circuit, this is the principle of solar power battery power generation.
