There are two ways of solar power generation, one is the light-heat-electricity conversion mode, the other is the direct conversion mode of light-electricity.
(1) The light-heat-electricity conversion method uses the heat generated by solar radiation to generate electricity. Generally, the solar collector converts the heat absorbed into the steam of the working medium, and then drives the steam turbine to generate electricity. The former process is the light-heat conversion process; The latter is a heat-electricity conversion process, similar to ordinary thermal power generation. The disadvantage of solar thermal power is that the efficiency is very low and the cost is very high. It is estimated that the investment of solar thermal power is at least 5 ~ 10 times more expensive than that of ordinary thermal power stations. A 1000MW solar thermal plant requires an investment of $2 billion to $2.5 billion, with an average investment of $2,000 to $2,500 for 1kW. Therefore, it can only be used on a small scale for special occasions, while large-scale use is economically uneconomical and cannot compete with ordinary thermal or nuclear power plants.
(2) Photoelectric direct conversion mode This mode is to use the photoelectric effect, the solar radiation can be directly converted into electric energy, the basic device of photoelectric conversion is the solar cell. Solar cell is a device that converts solar energy directly into electric energy due to the photogenic volt effect. It is a semiconductor photodiode. When the sun shines on the photodiode, the photodiode will turn the solar energy into electric energy and generate current. When many cells are connected in series or parallel, they can form a solar cell array with a relatively large output power. Solar cell is a promising new power source, which has three advantages of permanence, cleanliness and flexibility. Solar cells have a long life. As long as the sun exists, solar cells can be used for a long time with one investment. Compared with thermal power generation and nuclear power generation, solar cells do not cause environmental pollution. Solar cells can be both large and small, from the size of a mega kilowatt medium-sized power station to the size of a single household solar cell pack, which is unmatched by other power sources.
