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solar pannel greenhouse
2021-06-01
Photovoltaic effect
If light shines on the solar cell and the light is absorbed in the interface layer, photons with sufficient energy can excite electrons from covalent bonds in P-type silicon and N-type silicon, resulting in electron-hole pairs. Before recombination, the electrons and holes near the interface layer will be separated from each other by the electric field of space charges. The electrons move to the positively charged N zone and the holes to the negatively charged P zone.
Through the charge separation of the interface layer, an outward testable voltage will be generated between the P area and the N area. At this time, electrodes can be added on both sides of the silicon wafer and connected to a voltmeter. For crystalline silicon solar cells, the typical value of the open circuit voltage is 0.5 to 0.6V. The more electron-hole pairs generated by the light on the interface layer, the greater the current. The more light energy the interface layer absorbs, the larger the interface layer, that is, the larger the cell area, and the greater the current formed in the solar cell.
Sunlight shines on the semiconductor pn junction to form a new hole-electron pair. Under the action of the built-in electric field in the pn junction, holes flow from the n-zone to the p-zone, and electrons from the p-zone to the n-zone, which are formed after the circuit is turned on Current. This is the working principle of photovoltaic effect solar cells.
Light-electricity direct conversion method This method uses the photovoltaic effect to directly convert solar radiant energy into electrical energy. The basic device of light-electricity conversion is solar cells. A solar cell is a device that directly converts sunlight energy into electrical energy due to the photovoltaic effect. It is a semiconductor photodiode. When the sun shines on the photodiode, the photodiode will turn the sun’s light energy into electrical energy to produce Current. When many batteries are connected in series or in parallel, a square array of solar cells with relatively large output power can be formed. Solar cells are a promising new type of power source, with three major advantages of permanence, cleanliness and flexibility. Solar cells have a long lifespan. As long as the sun exists, solar cells can be invested once and used for a long time; and thermal power generation and nuclear power generation. In contrast, solar cells do not cause environmental pollution.
The main specific principle of photovoltaic power generation is the photoelectric effect of semiconductors. When a photon shines on a metal, its energy can be absorbed by an electron in the metal. The energy absorbed by the electron is large enough to overcome the internal gravity of the metal to do work, escape from the metal surface and become a photoelectron. Silicon atoms have 4 outer electrons. If pure silicon is doped with 5 outer electrons such as phosphorus atoms, it becomes an N-type semiconductor; if pure silicon is doped with 3 outer electrons, such as Boron atoms form a P-type semiconductor. When the P-type and N-type are combined together, the contact surface will form a potential difference and become a solar cell. When sunlight hits the P-N junction, holes move from the P-polar region to the N-polar region, and electrons move from the N-polar region to the P-polar region to form a current
System compositionedit
The photovoltaic power generation system is composed of a square array of solar cells, battery packs, charge and discharge controllers, inverters, AC power distribution cabinets, sun tracking control systems and other equipment. The role of some of its equipment is:
Battery phalanx
In the presence of light (whether it is the sun or the light produced by other luminous bodies), the battery absorbs light energy, and the accumulation of different signs of charge appears at both ends of the battery, that is, "photo-generated voltage" is generated, which is the "photovoltaic effect". Under the action of the photovoltaic effect, the two ends of the solar cell generate electromotive force to convert light energy into electric energy, which is an energy conversion device. Solar cells are generally silicon cells, which are divided into monocrystalline silicon solar cells, polycrystalline silicon solar cells and amorphous silicon solar cells.
Battery pack
Its function is to store the electric energy generated by the solar cell array when it is exposed to light and can supply power to the load at any time. The basic requirements of solar cell power generation for the battery pack used are: a. Low self-discharge rate; b. Long service life; c. Strong deep discharge capability; d. High charging efficiency; e. Low maintenance or no maintenance; f. Operating temperature Wide range; g. Low price.
Controller
It is a device that can automatically prevent the battery from overcharging and overdischarging. Since the number of cycles of charging and discharging of the battery and the depth of discharge are important factors that determine the service life of the battery, the charge and discharge controller that can control the overcharge or overdischarge of the battery pack is an indispensable device.
Inverter
It is a device that converts direct current into alternating current. Since solar cells and storage batteries are DC power sources,
If light shines on the solar cell and the light is absorbed in the interface layer, photons with sufficient energy can excite electrons from covalent bonds in P-type silicon and N-type silicon, resulting in electron-hole pairs. Before recombination, the electrons and holes near the interface layer will be separated from each other by the electric field of space charges. The electrons move to the positively charged N zone and the holes to the negatively charged P zone.
Through the charge separation of the interface layer, an outward testable voltage will be generated between the P area and the N area. At this time, electrodes can be added on both sides of the silicon wafer and connected to a voltmeter. For crystalline silicon solar cells, the typical value of the open circuit voltage is 0.5 to 0.6V. The more electron-hole pairs generated by the light on the interface layer, the greater the current. The more light energy the interface layer absorbs, the larger the interface layer, that is, the larger the cell area, and the greater the current formed in the solar cell.
Sunlight shines on the semiconductor pn junction to form a new hole-electron pair. Under the action of the built-in electric field in the pn junction, holes flow from the n-zone to the p-zone, and electrons from the p-zone to the n-zone, which are formed after the circuit is turned on Current. This is the working principle of photovoltaic effect solar cells.
Light-electricity direct conversion method This method uses the photovoltaic effect to directly convert solar radiant energy into electrical energy. The basic device of light-electricity conversion is solar cells. A solar cell is a device that directly converts sunlight energy into electrical energy due to the photovoltaic effect. It is a semiconductor photodiode. When the sun shines on the photodiode, the photodiode will turn the sun’s light energy into electrical energy to produce Current. When many batteries are connected in series or in parallel, a square array of solar cells with relatively large output power can be formed. Solar cells are a promising new type of power source, with three major advantages of permanence, cleanliness and flexibility. Solar cells have a long lifespan. As long as the sun exists, solar cells can be invested once and used for a long time; and thermal power generation and nuclear power generation. In contrast, solar cells do not cause environmental pollution.
The main specific principle of photovoltaic power generation is the photoelectric effect of semiconductors. When a photon shines on a metal, its energy can be absorbed by an electron in the metal. The energy absorbed by the electron is large enough to overcome the internal gravity of the metal to do work, escape from the metal surface and become a photoelectron. Silicon atoms have 4 outer electrons. If pure silicon is doped with 5 outer electrons such as phosphorus atoms, it becomes an N-type semiconductor; if pure silicon is doped with 3 outer electrons, such as Boron atoms form a P-type semiconductor. When the P-type and N-type are combined together, the contact surface will form a potential difference and become a solar cell. When sunlight hits the P-N junction, holes move from the P-polar region to the N-polar region, and electrons move from the N-polar region to the P-polar region to form a current
System compositionedit
The photovoltaic power generation system is composed of a square array of solar cells, battery packs, charge and discharge controllers, inverters, AC power distribution cabinets, sun tracking control systems and other equipment. The role of some of its equipment is:
Battery phalanx
In the presence of light (whether it is the sun or the light produced by other luminous bodies), the battery absorbs light energy, and the accumulation of different signs of charge appears at both ends of the battery, that is, "photo-generated voltage" is generated, which is the "photovoltaic effect". Under the action of the photovoltaic effect, the two ends of the solar cell generate electromotive force to convert light energy into electric energy, which is an energy conversion device. Solar cells are generally silicon cells, which are divided into monocrystalline silicon solar cells, polycrystalline silicon solar cells and amorphous silicon solar cells.
Battery pack
Its function is to store the electric energy generated by the solar cell array when it is exposed to light and can supply power to the load at any time. The basic requirements of solar cell power generation for the battery pack used are: a. Low self-discharge rate; b. Long service life; c. Strong deep discharge capability; d. High charging efficiency; e. Low maintenance or no maintenance; f. Operating temperature Wide range; g. Low price.
Controller
It is a device that can automatically prevent the battery from overcharging and overdischarging. Since the number of cycles of charging and discharging of the battery and the depth of discharge are important factors that determine the service life of the battery, the charge and discharge controller that can control the overcharge or overdischarge of the battery pack is an indispensable device.
Inverter
It is a device that converts direct current into alternating current. Since solar cells and storage batteries are DC power sources,
When the load is an AC load, the inverter is essential. According to the operation mode, the inverter can be divided into independent operation inverter and grid-connected inverter. The stand-alone inverter is used in the stand-alone solar cell power generation system to supply power to the independent load. Grid-connected inverters are used for grid-connected solar cell power generation systems. According to the output waveform, the inverter can be divided into square wave inverter and sine wave inverter. The square wave inverter has a simple circuit and low cost, but has a large harmonic component. It is generally used in systems with a few hundred watts or less and low requirements for harmonics. The sine wave inverter is expensive, but it can be applied to various loads.
