Analysis of the working principle of solar cells

The sun shines on the semiconductor pn junction, forming a new hole-electron pair. Under the action of the pn junction electric field, the hole flows from the n region to the p region, and the electron flows from the p region to the n region, and a current is formed after the circuit is turned on. This is how the photovoltaic effect solar cell works.

Solar power generation There are two ways of solar power generation, one is light-heat-electric conversion, and the other is light-electric direct conversion.

(1) The light-heat-electric conversion method generates electricity by utilizing thermal energy generated by solar radiation, and generally the solar collector collects the absorbed heat energy into a working medium vapor, and then drives the steam turbine to generate electricity. The former process is the light-to-heat conversion process; the latter process is the heat-to-electricity conversion process, which is the same as ordinary thermal power generation. The disadvantage of solar thermal power generation is that it is very inefficient and costly, and it is estimated that its investment is at least higher than ordinary fire. The power station is 5 to 10 times more expensive. A 1000MW solar thermal power station needs to invest between US$2 and US$2.5 billion, with an average investment of 1kW of US$2,000 to US$2,500. Therefore, it can only be applied to special occasions on a small scale, and large-scale utilization is economically uneconomical and cannot compete with ordinary thermal power plants or nuclear power plants.

(2) Light-to-electric direct conversion method This method uses photoelectric effect to directly convert solar radiation energy into electrical energy. The basic device for light-to-electrical conversion is solar cells. A solar cell is a device that converts solar energy directly into electrical energy due to the photovoltaic effect. It is a semiconductor photodiode. When the sun shines on the photodiode, the photodiode turns the solar light into electrical energy. Current. When many batteries are connected in series or in parallel, they can become a square of solar cells with relatively large output power. Solar cells are a promising new type of power source with three advantages of permanentness, cleanliness and flexibility. Solar cells have a long life. As long as the sun exists, solar cells can be used for long-term investment; with thermal power generation and nuclear power generation. In contrast, solar cells do not cause environmental pollution; solar cells can be large and small, ranging from large to medium-sized power plants of up to one million kilowatts, to solar cells that are only available to one household, which is unmatched by other power sources.

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