A solar cell is a device that responds to light and converts light energy into electricity. There are many kinds of 8 c purlin materials that can produce photovoltaic effect, such as: monocrystalline silicon, polycrystalline silicon, amorphous silicon, gallium arsenide, selenium indium copper, and the like. Their power generation principle is basically the same. Now, crystalline silicon is taken as an example to describe the photovoltaic power generation process. P-type crystalline silicon is doped with phosphorus to obtain N-type silicon to form a P-N junction.
When the light illuminates the surface of the solar cell, part of the photons are absorbed by the silicon material; the energy of the photons is transferred to the silicon atoms, causing the electrons to transition, and the free electrons are concentrated on both sides of the PN junction to form a potential difference when the circuit is externally connected. Under the action of this voltage, there will be a current flowing through the external circuit to generate a certain output power. The essence of this process is the process of converting photon energy into electrical energy.
First, solar power generation Solar power generation has two ways, one is the light-heat-electric conversion method, and the other is the light-electric direct conversion method.
1. The light-thermal-electrical conversion method generates electricity by utilizing the thermal energy generated by solar radiation. Generally, the solar collector collects the absorbed thermal energy into the working medium vapor, and then drives the steam turbine to generate electricity. The former process is the light-to-heat conversion process; the latter process is the thermo-electric conversion process, which is the same as ordinary thermal power generation. The shortcoming of solar thermal power generation is that it is very inefficient and costly. It is estimated that its investment is at least 5 to 10 times more expensive than ordinary thermal power plants. A 1000MW solar thermal power station requires an investment of 2 to 2.5 billion US dollars, and an average investment of 1kW is 2000 to 2500 US dollars. Therefore, it is suitable for small-scale special occasions, and large-scale utilization is economically uneconomical and cannot compete with ordinary thermal power plants or nuclear power plants.
2. Light-to-electric direct conversion method This method uses the photoelectric effect to directly convert solar radiation energy into electrical energy. The basic device for photoelectric-electrical conversion is solar cells. A 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 light into electrical energy. Current. When many batteries are connected in series or in parallel, they can become a square of solar cells with relatively large output power. Solar cells are a promising new type of power source with three advantages of permanentness, cleanliness and flexibility. Solar cells have long life, and solar cells can be used for long-term use as long as the sun exists; and thermal power generation and nuclear power generation In comparison, solar cells do not cause environmental pollution; solar cells can be large and small, ranging from large to medium-sized power plants of up to one million kilowatts, to solar cells that are only available to one household, which is unmatched by other power sources.
The solar AC power generation system is composed of a solar panel, a charging controller, an inverter, and a battery; the solar DC power generation system does not include an inverter. In order for the solar power generation system to provide sufficient power for the load, it is necessary to select each component reasonably according to the power of the electrical appliance. The following is an example of using 100W output power and 6 hours per day to introduce the calculation method:
First calculate the watt-hours consumed per day (including the loss of the inverter): If the conversion efficiency of the inverter is 90%, then when the output power is 100W, the actual required output power should be 100W/90. %=111W; if used for 5 hours per day, the output power is 111W*5 hours=555Wh.
Calculate the solar panel: Calculate the daily effective sunshine time of 6 hours, and consider the charging efficiency and the loss during charging. The output power of the solar panel should be 555Wh/6h/70%=130W. 70% of the solar panels are actually used during the charging process.