1. The composition of solar photovoltaic power generation system
Solar photovoltaic power generation systems are mainly composed of solar photovoltaic cells, photovoltaic system battery controllers, batteries and AC-DC inverters are the main components. The core components are photovoltaic cells and controllers. The role of various components in the system is:
Photovoltaic cells: photoelectric conversion.
Controller: Process control that acts on the entire system. There are many types of controllers used in photovoltaic power generation systems, such as 2-point controllers, multi-channel sequential controllers, intelligent controllers, and high-power tracking charge controllers. Currently, most of the controllers used in China are simply designed controllers. The controller is only used for communication systems and larger photovoltaic power plants.
Battery: A battery is a key component of a photovoltaic power generation system and is used to store the electricity converted from the photovoltaic cell. At present, China does not have a dedicated battery for photovoltaic systems, but uses a conventional lead-acid battery.
AC-DC inverter: Because its function is AC-DC conversion, the most important indicator of this component is reliability and conversion efficiency. Grid-connected inverters use maximum power tracking technology to maximize the conversion of photovoltaic cell energy into the grid.
2. Solar photovoltaic panels:
Solar cells are mainly made of single crystal silicon. Monocrystalline silicon is used to make a pn junction in a diode. The working principle is similar to that of a diode. However, in the diode, the external electric field that pushes the hole and electron movement of the pn junction is the solar field and the radiant heat (*) in the solar cell that pushes and affects the movement of the PN junction hole and the electron. It is also known as the principle of photovoltaic effect. At present, the efficiency of photoelectric conversion, that is, the efficiency of photovoltaic cells is about 13%-15% for monocrystalline silicon and 11%-13% for polysilicon. The latest technology also includes photovoltaic thin-film batteries.
In 1839, the French physicist A. E. Becquerel discovered in the laboratory the photovoltaic effect of the liquid (light shining on the metal plate of the liquid battery causes a slight change in the voltmeter in the battery circuit). So far, among all the materials found, it is made of monocrystalline silicon. The PN junction photovoltaic cell is the material with the highest photoelectric conversion efficiency.
3. Classification of solar photovoltaic power generation system:
At present, solar photovoltaic power generation systems can be roughly divided into three categories: off-grid photovoltaic storage systems, photovoltaic grid-connected power generation systems and the former two hybrid systems.
A) Off-grid photovoltaic storage system. This is a common solar application. It has been applied at home and abroad for several years. The system is relatively simple and adaptable. The scope of use is limited only because of the large size of its battery and the difficulty of maintenance.
B) Photovoltaic grid-connected power generation systems, when the power load is large, the solar power is insufficient to purchase power from the mains. When the load is small, or when there is no power available, excess power can be sold to the utility power. Under the premise of backing grid, the system saved the battery, which expanded the scope and flexibility of use, and reduced the cost.
C) A, B. A hybrid system, which is a system between the above two parties. The program has strong adaptability. For example, it can adjust its own power generation strategy based on the peak-to-valley power price of the power grid. However, its cost and operating costs are higher than the above two options.
Photovoltaic industry investment focus should be concentrated in the field of thin film photovoltaic cells
The new energy sector faces a dilemma of high valuation in the short term The global photovoltaic industry maintains a fever, and the rise of thin film photovoltaic cells
According to the latest data from Solarbuzz, the installed capacity of the global PV system in 2007 was 2826 MW, a 62% increase over 2006, of which Germany’s PV system capacity in 2007 was 1328 MW (accounting for 47% of the total), which ranked first, with a growth rate of 38. %, followed by Spain’s 640MW (accounting for 23%), a growth rate of 480%, the United States’ 220MW (8% of the total), a growth rate of 57%, the Japanese market share continues to decline, and the capacity of the installation in 2007 is only 230MW (accounting for 8%), a decline of 22%.
In 2007, global solar cell production reached 3,436 MW, an increase of 56% compared to 2006. Chinese manufacturers’ market share in 2007 increased from 20% in 2006 to 35%, while Japanese manufacturers' market share fell from 39% in 2006 to 26%, Japanese manufacturers' market share decline In addition to being affected by factors such as the tight supply of upstream silicon materials and the decline in the capacity of photovoltaic systems in Japan's domestic market, there is also a considerable relationship between the Japanese manufacturers' development of the next-generation thin-film solar cell field.
In 2007, the production of thin-film solar cells (including a-Si, μc-Si, CdTe, CIGS, etc.) continued to outperform the overall industry. In 2007, the production of thin-film solar cells reached 400MW, which was a significant increase of 120% from 181MW in 2006. 07 The market share of thin-film solar cells increased from 8.2% in 2006 to 12% in 2007. Under the continued tight supply of silicon raw materials in the upstream, thin-film solar cells have further improved battery conversion efficiency and cost advantages in large-area production. There is room for further improvement in the share.
Investment focus should be transferred to the field of thin film photovoltaic cells for excavation
At present, the crystalline silicon photovoltaic cell industry presents a state of fattening and thinning. The profitability of the midstream and downstream battery module plants continues to shrink, and more photovoltaic cell plants have been transferred to the development of thin film photovoltaic cell technology. Currently, domestic manufacturers are planning for the expansion of upstream silicon materials in the future. Will face greater capacity to go into doubt, we recommend that the focus of the photovoltaic industry investment should be transferred to the field of thin film batteries to do excavation, we are currently optimistic about Vosges shares (002083.SZ, Rmb14.58, not rated) CIGSSe photovoltaic cell project.
Electronic Technology Group's 18th Decryption of "Shenzhou Seven" Solar Cell array
"Every time the spacecraft launches into the state of separation of stars and arrows, my heart and my colleagues will all mention the eyes of a blind man's ears, and they will hold their ears until they hear the command and control room sending out 'battery windsurfing starts!' The password only took a big breath, and then hugged and cheered together. That happy celebration didn't match it.†In the simple office of the 18th China Electronics Technology Group Corporation, the Director of the Space General Room, Aerospace Han Zhensen, a power system expert, described to the reporter their indissoluble bond with the Shenzhou spaceship. His words contained a kind of affectionate affection.
From the first man-made earth satellite to today’s Shenzhou VII spacecraft, the 18th Institute has always been responsible for cutting-edge scientific research projects—the development, production and assembly of solar arrays, and has created a source for China’s stepping into a space power.
The battery is on the spacecraft, it is like the blood on the person.
The eighteen power systems responsible for the spacecraft are among the seven systems for manned space projects. It is a sub-system of the spacecraft system. "It's not too much to say about its vitality. It's like people's blood. This system is not working. The spacecraft can't move." Han Zhengsen, who has worked on batteries for more than 20 years, has been trying to explain the hard technology in popular language. noun.
From "Shenzhou" No.1 to "Shenzhou" No.7 and No.18, a total of 80 solar panels were produced and supplied for the "Shenzhou" spacecraft. These panels are deployed after the spacecraft enters the orbit, like a pair of wings, to ensure the normal flight of the spacecraft. This pair of wings is always following the sun under the automatic adjustment of the solar angle meter and light sensor. "No matter what the attitude of the spacecraft, these wings are kept at a right angle to the sun, letting the light shine straight to the battery array. "Battery arrays, like generators, convert light energy into electricity, which is constantly fed to other systems in the spacecraft. When the spacecraft is in orbit, solar arrays are the only subsystems in the spacecraft that actively provide energy.
The reason why "array" is because of the collection of several major units. The power supply array provides direct power for the spacecraft, and the charging array charges the battery pack. In the shaded area, the battery pack then outputs the stored electrical energy to power the spacecraft. Solar arrays are a direct source of energy for spacecraft. Without it, the spacecraft cannot work.
God Seven is identical to God Six battery array
"Shenzhou 7" is the first spacecraft of the second phase of China's manned space project. One of the main missions in this space is to achieve the first spacewalk for Chinese astronauts and to carry three astronauts at the same time. Therefore, high requirements are placed on the design of each system. Han Zhensen explained that the main power solar array is one of the main components of the power subsystem. When the light is illuminated, the spacecraft provides load power and charges the battery pack. This time, the solar array has no rail power supply, and the technical standard for the eight main power boards is exactly the same as “Shenzhou VIâ€.
Han Zhensen sketched the spacecraft on a piece of paper and continued to explain: The two wings that everyone sees on television are the left and right wings of the main power solar array.
From the TV broadcast, we can see the small blocks on the panel. What kind of component is that? Han Zhensen explained that it is a monocrystalline silicon high-efficiency single-cell battery, the entire spacecraft used a total of more than 10,000 films, photoelectric conversion efficiency and fabric coefficient reached the international advanced level of similar products.
Han Zhensen revealed that the material and technological level of Shenqi Solar Cell array has also reached the international advanced level. "This material is very advanced and fully capable of dealing with the complex environment in space. This is a major breakthrough in China's aerospace technology."
Flying satellites also have magical batteries
There are two highlights of this "Spiritual Seven" space trip. One is the astronaut walking out of the cabin and the other is flying with satellites. The battery on this satellite was also developed by eighteen.
Han Zhensen introduced that the satellite structure with flying satellites is hexahedron, in which five surfaces are affixed with solar cells. Researchers have selected three-junction gallium arsenide solar cells with higher conversion efficiency as the basic power generation unit, and the average photoelectric conversion efficiency of single cells has reached 27%. It is China's first batch application of such batteries to satellite projects. The in-orbit operation data of the SZ-7 spacecraft's tiny satellite companion satellite will provide valuable in-orbit flight data for the application of the triple-junction gallium arsenide cell in the second phase of the manned space project.
Ground closure training with analog power supply equipment
In addition to safeguarding the spacecraft’s on-orbit power, the 18th Institute also undertook all the power supply of the spacecraft during the ground and designed and developed the ground-based analog power supply equipment. This is also the magic of the "Shenzhou 7" power protection system.
When the astronauts are in closed training, they must simulate the various states of space flight to adapt to the space environment. The power supply system must also be synchronized, and the space attitude of the battery array should be designed according to the relationship curve between the sun and the spacecraft and the earth. This simulation requires that the mission be completed within 30 minutes of negative timing.
Han Zhensen explained "negative 30 points": usually the spacecraft launch is called "zero seconds", "zero seconds" before the "negative" timing, "zero seconds" after the launch of the launch after the "positive" timing. The ground-based analog power supply equipment is not a simple power supply, but simulates the power supply characteristics of the solar cell wings in space orbits in terms of various characteristics. The analog power supply time began with a single test of the power system, and the test after the completion of the entire ship was completed. It did not separate from the hull until 30 minutes before the launch of the spacecraft. For each launch, technicians must be in place 4 months in advance to ensure the astronauts' closed training. This is also the most critical training period before the ascent.
Small battery, shining bright. The scientists and technicians from God 1 to God 7 and 18 wrote the pen of the Chinese manned space flight.