Principle of photovoltaic power Generation

Photovoltaic (pv) effect

If light hits the solar cell and is absorbed at the interface layer, photons with enough energy can excite electrons from covalent bonds in both p-type and N-type silicon to create electron-hole pairs. Electrons and holes near the interface layer will be separated from each other by an electric field of space charges before recombining. The electrons move toward the positively charged N region and the holes toward the negatively charged P region. Charge separation through the interface layer will generate an outward testable voltage between the P and N zones. Electrodes can be added to both sides of the silicon wafer and connected to a voltmeter. For crystalline silicon solar cells, the typical value of open circuit voltage is 0.5~0.6V. The more electron-hole pairs generated by illumination at the interface layer, the greater the current. The more light absorbed by the interface layer, the larger the area of the interface layer, or cell, and the greater the current formed in the solar cell

The principle of

Solar light on the semiconductor P-N junction, the formation of a new hole-electron pair, under the action of the p-N junction built electric field, the hole flows from N to P region, the electron flows from P region to N region, after the circuit is connected to form a current. This is how photovoltaic solar cells work.

Solar power can be generated in two ways, one is a light-thermal-electric conversion mode, the other is a direct light-electricity conversion mode.

(1) Photothermal-electric conversion mode generates electricity by using the heat energy generated by solar radiation. Generally, the solar collector converts the absorbed heat energy into steam of working medium, and then drives the turbine to generate electricity. The first is a photothermal conversion process; The latter process is a thermal-electric conversion process, similar to ordinary thermal power generation. The disadvantage of solar thermal power generation is that the efficiency is very low and the cost is very high. It is estimated that its investment is at least 5~10 times more expensive than ordinary thermal power stations.

(2) Photoelectric direct conversion mode This mode uses photovoltaic effect to directly convert solar radiation energy into electric energy. The basic device of photoelectric conversion is solar cell. Solar cell is a device that converts solar light energy directly into electric energy due to the photogenerating volt effect. It is a semiconductor photodiode. When the sun shines on the photodiode, the photodiode will convert the sun's light energy into electric energy and generate an electric current. When many cells are connected in series or parallel, a solar array with relatively large output power can be formed. Solar cells are a promising new power source with three advantages: permanence, cleanliness and flexibility. Solar cells have a long life span. As long as the sun exists, solar cells can be invested once and used for a long time. Compared with thermal power generation and nuclear power generation, solar cells do not cause environmental pollution.