Solar cell is a device that responds to light and can convert light energy into electricity. There are many kinds of materials that can produce photovoltaic effect, such as monocrystalline silicon, polysilicon, amorphous silicon, gallium arsenide, selenium indium copper, etc. Their power generation principles are basically the same. Now take crystalline silicon as an example to describe the process of photo power generation. P-type crystalline silicon can be doped with phosphorus to obtain n-type silicon, forming p-n junction.

When the light shines on the surface of the solar cell, some photons are absorbed by the silicon material; The energy of photons is transferred to the silicon atom, making the electrons jump and become free electrons, which gather on both sides of the p-n junction to form a potential difference. When the external circuit is connected, under the action of this voltage, there will be current flowing through the external circuit to produce a certain output power. The essence of this process is: the process of converting photon energy into electrical energy.

    There are two ways of solar power generation, one is light heat electricity conversion, the other is light electricity direct conversion.

(1) 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 the steam of the 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 ordinary thermal power generation. Solar thermal power station has high efficiency. However, due to its industrialization at the initial stage, the current investment is high. A 1000MW solar thermal power station requires an investment of US $2-2.5 billion, with an average investment of US $2000-2500 for 1kW. Therefore, it is suitable for small-scale special occasions, and large-scale utilization is economically uneconomical, and it cannot compete with ordinary thermal power plants or nuclear power plants.
(2) Light electricity direct conversion mode this mode uses photoelectric effect to directly convert solar radiation energy into electrical energy. The basic device of light electricity conversion is solar cells. Solar cell is a device that directly converts solar energy into electrical energy due to photovoltaic effect. It is a semiconductor photodiode. When the sun shines on the photodiode, the photodiode will convert the solar energy into electrical energy and generate current. When many cells are connected in series or in parallel, they can become a solar cell array with relatively large output power. Solar cell is a promising new power source, which has three advantages: permanence, cleanness and flexibility The service life of solar cells is long. As long as the sun exists, solar cells can be used for a long time with one-time investment; Compared with thermal power generation and nuclear power generation, solar cells will not cause environmental pollution; Solar cells can be large, small and medium-sized at the same time, ranging from medium-sized power stations of one million kilowatts to solar cell packs for only one household, which is unmatched by other power sources.