What is the principle of photovoltaic power generation?

Principle of photovoltaic power generation: photovoltaic power generation is a technology that directly converts light energy into electric energy by using photovoltaic effect of semiconductor interface. The key to this technology is solar cells. After the solar cells are connected in series, they can be packaged and protected into a large-area solar cell module, which can be combined with components such as a power controller to form a photovoltaic power generation device. The main principle of photovoltaic power generation is the photoelectric effect of semiconductors. When a photon hits a metal, its energy can be completely absorbed by an electron in the metal. The energy absorbed by electrons is large enough to overcome the attraction inside the metal and escape from the surface of the metal to become photoelectrons. Silicon has four outer electrons. If pure silicon is doped with atoms with five outer electrons, such as phosphorus atoms, it will become an N-type semiconductor. If pure silicon is doped with atoms with three outer electrons, such as boron atoms, a P-type semiconductor is formed. When P-type and N-type are combined, the contact surface will form a potential difference, which will become a solar cell. The sunlight on the film cover irradiates the semiconductor pn junction, forming a new hole-electron pair. Under the action of the built-in electric field in pn junction, holes flow from N region to P region, and electrons flow from P region to N region. When the circuit is connected, a current is formed. This is the working principle of photoelectric effect solar cells. There are two ways of solar power generation, one is light-heat-electricity conversion, and the other is direct photoelectric conversion. (1) The light-heat-electricity conversion mode uses the heat energy generated by solar radiation to generate electricity. Generally, solar collectors convert the absorbed heat energy into working medium steam, and then drive a steam turbine to generate electricity. The former process is photothermal conversion process; The latter process is thermoelectric conversion, just like ordinary thermal power generation. The disadvantages of solar thermal power generation are 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. (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 cells are devices that directly convert solar energy into electric energy through photovoltaic effect. It is a semiconductor photodiode. When the sun shines on the photodiode, the photodiode will convert solar energy into electric energy and generate current. When a plurality of batteries are connected in series or in parallel, it can become a solar cell array with relatively high output power. Solar cell is a promising new energy source, which has three advantages: permanence, cleanness and flexibility. Solar cells have a long life. As long as the sun exists, an investment will last forever. Compared with thermal power generation and nuclear power generation, solar cells will not cause environmental pollution.