Solar cells are devices that directly convert light energy into electrical energy by photoelectric effect or photochemical effect.
The principle of solar cells
Sunlight shines on the p-n junction of the semiconductor to form new hole-electron pairs. Under the action of the electric field of the p-n junction, holes flow from the n region. to zone p, electrons flow from zone p to zone n and a current is formed once the circuit is connected. This is how photovoltaic solar cells work.
1. Solar power generation methods There are two solar power generation methods, one is light-heat-electricity conversion method and the other is direct light-electricity conversion method.
(1) The light-heat-electricity conversion method uses thermal energy generated by solar radiation to produceelectricity. Generally, a solar collector converts the absorbed thermal energy into steam as the working fluid and then drives it away. a steam turbine to produce electricity. The first process is a light-heat conversion process; the second process is a heat-electricity conversion process, which is the same as ordinary thermal power generation. The disadvantages of solar thermal power generation are that its efficiency is very low and its cost is high. Its investment is estimated to be at least higher than that of ordinary thermal power generation. The power plant is 5-10 times more expensive. A 1,000 MW solar thermal power plant requires an investment of 2 to 2.5 billion US dollars. the average investment for 1 kW is 2,000-2,500 US dollars. Therefore, it can only be used on a small scale on special occasions, and large-scale useis not economically profitable and cannot compete with ordinary thermal or nuclear power plants.
(2) Direct light-to-electricity conversion method This method uses the photoelectric effect to directly convert solar radiation energy into electrical energy. The basic device for converting light into electricity is the solar cell. A solar cell is a device that directly converts solar energy into electrical energy through the photovoltaic effect. When the sun shines on the photodiode, the photodiode converts light energy from the sun into electrical energy, producing current. When many batteries are connected in series or parallel, a solar cell array with relatively large output power can be formed. Solar cells are a promising new energy source with three major advantages: Solar cells have a longlifespan and can be invested once and used for a long time as long as the sun exists, they are different from thermal power generation; and nuclear energy production. In comparison, solar cells will not cause environmental pollution; Solar cells can be used in both large, medium and small sizes, ranging from a medium-sized power plant with a million kilowatts to a solar battery for a household. only, which is unmatched by other energy sources.