A solar cell is a device that responds to light and converts light energy into electricity. There are many kinds of materials that can produce photovoltaic effect, such as monocrystalline silicon, polycrystalline silicon, amorphous silicon, gallium arsenide, selenium and other copper. Their power generation principle is basically the same, now crystal silicon as an example to describe the photovoltaic power generation process. P-type crystalline silicon doped with phosphorus can be N-type silicon, the formation of P-N junction.
When the light is irradiated on the surface of the solar cell, a part of the photons are absorbed by the silicon material; the energy of the photon is transferred to the silicon atoms so that the electrons are transitioned and the free electrons are formed on both sides of the PN junction to form a potential difference. When the external circuit is turned on , In the role of the voltage, there will be a 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.
First, the solar power There are two ways of solar power generation, one is the light - heat - electricity conversion, the other is the optical - electrical direct conversion.
(1) light - heat - electricity conversion through the use of solar radiation generated by thermal energy, usually by the solar collector will absorb the heat transfer
Into the refrigerant refrigerant, and then drive the turbine power generation. The previous process is the light-heat conversion process; the latter process is the thermal-electrical conversion process, as is the case with ordinary thermal power generation. The disadvantage of solar thermal power generation is the low efficiency and high cost, it is estimated that its investment at least 5 to 10 times higher than the ordinary thermal power plant. A 1000MW solar thermal power plant needs to invest 20 to 25 billion US dollars, an average of 1kW investment of 2000 to 2500 US dollars. Therefore, the application of small-scale special occasions, and large-scale use in the economy is very cost-effective, can not compete with ordinary thermal power plants or nuclear power plants.
(2) optical - electrical direct conversion mode This method is the use of photoelectric effect, the solar radiation can be directly converted into electrical energy, optical - electrical conversion of the basic device is the solar cell. The solar cell is a device that converts solar energy directly into electrical energy due to the photovoltaic effect. It is a semiconductor photodiode. When the sun shines on the photodiode, the photodiode turns the solar energy into electricity. Current. When many batteries in series or in parallel can become a relatively large output power of the solar cell array. Solar cells are a promising new power supply, with permanent, clean and flexible three major advantages of solar cells long life, as long as the sun exists, solar cells can be an investment and long-term use; and thermal power, nuclear power generation Compared to solar cells will not cause environmental pollution; solar cells can be large and small simultaneously, large to one million kilowatts of medium-sized power plants, small to only one for the use of solar cells, which is unmatched by other power