Photovoltaic power generationIt is a technology that directly converts light energy to electricity using the photovolt effects of semiconductor interfaces. The key element of this technology isSolar cellsI don't know. Solar cells are bundled and protected to form a large area of solar cell components, which, together with components such as power controllers, form photovoltaic power units。
Optical effects
If the light is irradiated on solar cells and the light is absorbed in the interface, photons with sufficient energy are able to stimulate electrons from the co-priced key in both p- and n-silics, so as to create electronic-space pairs. Electronics and hollows near the interface layer will be separated from each other through the power field of the space charge before they are compounded. Electronics move to area n with positive power and empty caves to area p with negative electricity. The charge separation through the interface level will generate an outwardly testable voltage between p and n. At this point, electrodes can be added to both sides of the silicone and access to the voltage table. For crystalline silicon solar cells, the typical value of open circuit voltage is 0. 5 to 0. 6 v. The more electron-density from light on the interface, the larger the current. The greater the light energy absorbed in the interface, the larger the interface, the size of the battery, the greater the currents formed in solar cells。
Ii. Rationale
The sun shines on the semiconductor p-n knot, creating a new vacuum-electronic pair, which, with the help of a power farm built within the p-n knot, flows from area n to area p, from area p to area n, and from area n, which is connected to the electrical circuit. That's how the pv solar cells work。
There are two ways in which solar power is generated, one by photo-thermal-electric conversion and the other by direct photo-electric conversion。
(1) photo-thermal-electric conversions generate electricity by using thermal energy generated by solar radiation, typically by converting thermal energy absorbed by solar collectors into working-quality vapour, and by re-driving the power from the turbines. The former process is photo-thermal conversion; the latter process is thermal-electric conversion process, as is the case with normal fire power generation. Solar thermal power generation has the disadvantage of being inefficient and costly, and is estimated to cost at least 5-10 times more than a normal fire station。
(2) the direct pv conversion method is the direct conversion of solar radiation into electrical energy using photo-voltaic effects, the basic device for which is solar cells. Solar cells are a device that directly converts solar light energy to electrical energy as a result of the photovoltaic effect, a semiconductor pv diode, which transforms solar light into electrical energy and generates currents when solar light hits the pv diode. When many batteries are linked or joined together, they become solar arrays with a relatively large output power. Solar cells are a promising new source of electricity, with three main advantages: permanent, clean and flexible. Solar cells have a long lifespan, and they can be used with a single investment and on a long-term basis as long as the sun exists; they do not cause environmental pollution compared to fire and nuclear power generation。
The pv system consists of solar arrays, batteries, charge controllers, reversers, exchange distribution cabinets, solar tracking control systems, etc. The role of some of its equipment is:
Battery array
In the case of light (whether from the sun or from other luminescences), the battery absorbs light energy, and at both ends the battery accumulates an alien charge, i. E. Produces a “photovoltaic voltage”, i. E. A “photo-volt effect”. The two ends of the solar cell generate electric motion, conversion of light energy to electrical energy, as a device for energy conversion, as a result of the photovoltaic effect. Solar cells are typically silicon cells, divided into single-crystal silicon solar cells, multicrystal silicon solar cells and non-crystalin solar cells。
Batteries
The function is to store electrical power from solar arrays when they are luminescenced and to supply the load at any time. The basic requirements for solar power generation for batteries to be used are: (a) low self-release rate; (b) long useful life; (c) strong deep discharge capacity; (d) high charge efficiency; (e) low or no maintenance; (f) wide work temperature range; and (g) low cost。
Controller
Equipment that automatically prevents battery overcharge and discharge. Since the frequency and depth of discharge of the battery is an important factor in determining the useful life of the battery, recharge controllers that control the battery overcharge or discharge are essential。
Reverser
It is a device for the conversion of direct currents into communication. As solar cells and storage batteries are a direct power source
When the load is a communication load, the reverser is essential. Inverters can be divided into stand-alone and grid-connected reversers, depending on the mode of operation. Independently operated reversers are used for stand-alone solar-cell power systems, providing power to stand-alone loads. Net-connected reversers are used for grid-connected solar cell power systems. Inverters can be divided by output wave type into square wave reversers and sine wave reversers. The square-wave reverser circuits are simple and low-priced, but they have a large harmonization weight, usually for systems that are under hundreds of watts and less than the requirements of the wave. Sine wave reversers are costly but can be applied to various loads。
4. System classification
Pv systems are divided into independent pv systems, grid-connected pv systems and distributed pv systems。
Ipv is also called off-grid. It consists mainly of solar battery assemblies, controllers, and batteries, which also need to be equipped with communication reversers if they are to provide power for communication loads. Independent photovoltaic power stations include village power systems in remote areas, solar household power systems, communications signal power sources, cathode protection, solar road lights and a variety of independently operational photovoltaic systems with batteries。
2. Net-based photovoltaic power is direct access to the public grid after the direct current power generated by the solar component has been converted by the grid reverser to the exchange power that meets the requirements of the municipal grid。
It can be divided into grid-connected power systems with and without batteries. A grid-connected power system with batteries is programmable and can be incorporated or withdrawn from the grid as required, as well as a back-up power supply that can be provided on an emergency basis when the grid is shut down. Photovoltaic grid-based power systems with batteries are often installed in residential buildings; grid-connected power systems without batteries do not have dispatchability and backup power, and are generally installed on larger systems. The main feature of grid-connected photovoltaic power generation, which has a centralized large grid-connected photovoltaic power station, is that it is generally a national power station, with the power generated being delivered directly to the grid, with the power being distributed from the grid to the users. However, such power plants are heavily invested, have a long construction cycle, have a large land area and have not developed much. In contrast, decentralized mini-grid photovoltaics, particularly integrated photovoltaics in photovoltaic buildings, are mainstreamed in grid-connected photovoltaics due to the advantages of small investment, rapid construction, small land area and strong policy support。
3. Distributive photovoltaic power systems, also known as decentralized or distributed power generation, are those that deploy smaller photovoltaic power generation systems on or near user sites to meet specific user needs, support the economic operation of existing distribution networks or meet both requirements。
The basic equipment for the distributed photovoltaic power generation system consists of photovoltaic battery components, photovoltaic arrays, direct flow tanks, direct flow distribution cabinets, network reversers, exchange distribution cabinets, etc., as well as electrical system monitoring and environmental monitoring units. The mode of operation is that, under conditions of solar radiation, solar cell assembly arrays of the pv system convert solar energy to the output of electricity, which is sent to the direct-flow distribution cabinets by direct-flow tanks, which is reversed from grid-connected retroverters to the own load of the exchange power supply building, and which is regulated by the grid connection for excess or insufficient electricity。
5. Strengths and disadvantages
The advantages of solar photovoltaics, compared to commonly used power generation systems, are mainly reflected in:
Solar power generation is called the ideal new energy source. No risk of depletion; 2 safe, secure, no noise, absolutely clean (no hazard) except for pollution emissions; 3 free of geographical distribution of resources, making use of the advantages of building space; 4 free of fuel consumption and power transmission lines to generate electricity locally; 5 high-quality energy; 6 user emotionally acceptable; 7 short construction cycle and short time to access energy。
Disadvantages:
The energy density of exposures is small, i. E., they take up large areas; the energy available is associated with weather conditions such as four seasons, day and night, and cloud. The use of solar energy for power generation is costly, but the use of solar energy is low and cannot be widely applied, mainly in special circumstances such as satellites。
User solar power: (1) small power sources, ranging from 10 to 100 w, are used for civilian and military life electricity, such as lighting, television, recorders, etc., in remote areas where electricity is not available, such as the highlands, islands, pastoral areas, border posts; (2) 3-5kw family roofs are connected to network power generation systems; and (3) photovoltaic water pumps: deep water wells to address non-electricity are used for irrigation。
Ii. In the area of transport, such as beacon lamps, traffic/railway lights, traffic alerts/markers, street lights, high-altitude barrier lamps, highway/railway radio booths, power supply for unmanned road watch。
Iii. In the area of communications/communications: solar unmanned microwave links, cable maintenance stations, radio/communication/calling power systems; rural wave telephone pv systems, small communication machines, gps power for soldiers, etc。
In the oil, marine and meteorological fields: the cathode of oil pipelines and reservoir gates protects solar power systems, the life of oil drilling platforms and emergency power sources, marine detection equipment, meteorological/hydrological observation equipment, etc。
5. Power sources for household lamps such as courtyard lamps, street lights, handheld lamps, camp lights, mountain-riding lights, fishing lights, black lights, gel-cutting lamps, energy-saving lamps, etc。
Optical voltage stations: 10 kw-50 mw independent photovoltaic plants, windlight (wood) complementary power stations, various large parking plants charging stations, etc。
Solar construction, which combines solar power generation with construction materials, makes future large buildings self-sufficient in electricity, is a major future development。
Viii. Other areas include: (1) car matching: solar vehicles/electric vehicles, battery charging equipment, car air conditioning, air exchange fans, cold drinking tanks, etc.; (2) regenerative power generation systems for solar hydrogen and fuel cells; (3) desalination equipment for electricity supply; (4) satellites, spacecraft, space solar power stations, etc。
