太阳能光伏报告【外文翻译】

外文翻译原文Solar Photovoltaic ReportMaterial Source: ABS Energy Research 2009 Author: Anonymous Author PV Industry Value ChainThe PV industry has three essential components, which constitute the value chain, each dependent on each other. Some companies concentrate on individual segments of the value chain others address all segments as integrated solar PV companies. These components are:•Feedstock•Solar PV cells and modules•Balance of systemRaw silicon is by far the most prevalent feedstock for solar cells, although reduced to 87% from 94% in the last few years. Bulk silicon is separated into multiple categories according to crystallinity and crystal size in the resulting ingot, ribbon or wafer.•Monocrystalline silicon (c-Si) is often made using the Czochralski process. Single-crystal wafer cells are expensive because they are cut from cylindrical ingots •Poly- or multi-crystalline silicon (poly-Si or mc-Si) is made from cast square ingots. They are cheaper because they are less expensive to produce than single crystal cells but they are less efficient•Ribbon silicon is formed by drawing flat thin films from molten silicon and they have a multi-crystalline structure. These cells have lower efficiencies than poly-Si, but save on production costs due to a great reduction in silicon waste because this approach does not require sawing from ingots.•New Structures: These new compounds are special arrangements of silicon, such as organically modified silica, a-Si, and nanotechnological combinations that can dramatically improve efficiency.Thin film alternatives to thick crystal accounted for 13% of cells produced in 2007 according to Prometheus Institute. The various thin-film technologies currently being developed reduce the amount of light-absorbing material required in creating asolar cell. Such coatings have about one percent of thick crystal’s depth.PolysiliconThere are two sources of solar grade (SoG): silicon feedstock producers of electronic grade (EG) silicon for the Integrated Circuit (IC) industry producing semiconductors, and more recently several companies beginning to use metallurgical silicone (MG-Si) directly as a feedstock. It is generally referred to as multi-crystalline silicon, or poly-silicon (poly-Si, or poly). Until recently, SoG came from off-spec and waste silicon, produced either during the poly-silicon purification process or during ingot and wafer production but poly-silicon companies are now producing SoG specifically for solar PV use.Silicon must be highly purified for use as a semiconductor material, and electronic grade silicon requires a higher degree of purification than solar grade. For use in solar photovoltaics the silicon must be 99.9999% pure (often referred to as ‘six nines’ or 6N pu re), while electronic grade silicon is typically 9N to 11N.Silicon of either grade must undergo a lot of processing and passes through several stages. The first stage is the extraction of quartz from a silica mine. The quartz is heated in a furnace with a carbon source, such as coal and coke, producing liquid silicon, which is refined and allowed to solidify. It is known as metallurgical silicon (MG-Si), which is 96% - 99% pure and is used by the steel industry a tiny proportion gets diverted to the electronic semiconductor industry. In turn what was a small proportion of that quantity was directed to Photovoltaics. In the very recent past Photovoltaics equalled that used by electronics but of course of a different quality.MG-Si can be refined by several methods to produce poly-silicon, the most common of which is the Siemens, or chemical vapour deposition (CVD) process now used for about 90% of production. It involves chemical deposition of trichlorosilane (TCD) gas on heated rods. The final product is a rod of silicon, which is then broken into‘chunks’ or granules of polysilicon. Other processes are the fluidised bed reactor (FBR) and a process developed by Union Carbide in the 1980s and now owned by REC, a dedicated Norwegian manufacturer of solar grade feedstock..The chunk or granular poly-silicon is then refined with one of several processes. The Czochralski (CZ) and float zone methods produce mono-crystalline ingots. Directional solidification or casting, ribbon, and sheet techniques produce multi-crystalline structures.The length of time of creating the crystal structure and the costs of electrical power needed to complete the process have been seen as blocks to further viability, although clever techniques are being adopted, such as slicing thinner wafers or improving performance by ultrasonic plating.Thin Film Photovoltaic (TFPV) technologyVarious thin film technologies are being developed from lab to fab so as to reduce the amount of light absorbing material required in a solar cell. Thin film PV uses thin film coating technologies and uses less material because the active area of the cell is usually only 1 to 10 micrometers thick, compared with 100 to 300 micrometers for thick film. An additional advantage is that thin-film cells can be manufactured in a large-area automated, continuous production process.The most common thin-film technologies use amorphous silicon (a-Si), cadmium telluride (CdTe), copper-indium-selenide (CIS) and copper-indium-gallium-diselenide (CIGS). Of these, CIGS has demonstrated the highest laboratory efficiency at 19.5% with CdTe close behind. CIGS thin-film technologies can be placed on a wide variety of substrate materials making it possible to manufacture very lightweight, flexible solar cells on metals and plastics. To put it into perspective, the thickness of a flexible CIGS device is approximately the same as the thickness of a human hair, making it very flexible and lightweight. Another specialised thin fill technology uses gallium arsenide (GaAs) with multijunction cells, which consist of multiple thin films. GaAs multijunction devices are the most efficient solar cells to date, reaching a record high of 40.7% efficiency under solar concentration and laboratory condition but are some time from commercialisation.The manufacturing processes for thin films are quite different from those used to produce SoG silicon. It is difficult for the companies introducing CIGS to adapt solar cell manufacturing technology. In addition, individual manufacturers are pursuing different processes. Applied Materials Inc. have been able to usefully employ their experience in manufacturing production lines for flat TV and computer screens to create plant capable of sputtering glass panels 2.2m X 2.6m. Moler Baer in India have achieved certificated start up plant capable of producing these panels equivalent to 40MW pa as have T-Solar global with a 45MW production line in Spain both starting early 2009. The coating is microns thin and the panels reduce electrical complexity and are reckoned to reduce set up by 20%.Ingot and wafer productionIngot and wafer production are usually integrated in the same production facility. It in this area that shortages in feedstock for the PV market has had the most effect including drawing China to establish a large export market in the last couple of years. In 2008 Chinese shipments of ingots and wafers reached 2,092 MW, around 40% of annual sales of cells in that year, and an increase from 1,049 MW in 2007 and 425 MW in 2006. Prices have declined and will continue to do so.Silicon feedstock is melted and, from that, thin-walled octagonal tubes of crystal about 18 feet tall are created by Monocrystalline Pullers. These tubes are transported to automated laser machines on which wafers are cut from the octagon faces. The wafers are 180 to 350 micrometer thick. Subsequently, the wafers are cleaned before being moved on to a cell line where each is given a positive and negative junction.Since the late 1990s several companies have focused on this rung of the value chain ladder. Scan Wafer in Norway, Deutsche Solar in Germany and PV Crystalox in Germany and the UK are competing for the global leadership in the production of wafers. New entrants competing in this market are Sumco and JFE of Japan, Pillar of Ukraine and Emix of France.Cell and module manufacture is, as the term describes, the manufacture of cells from silicon feedstock or from thin film, and the assembly of cells into modules. Solar cells are made from silicon wafers, by applying a variety of different metals and producing a silicon cell, a number of which are attached together in strings using solder-coated copper wire. These strings are assembled between two sheets of glass together with various plastic type materials which are then laminated to form a composite structure similar to a laminated windshield. A junction box, framing and wiring are attached to create a module approximately four feet by six feet that, when exposed to sunlight, will produce 300 watts of DC electricity. (Source: RWE Schott)译文太阳能光伏报告资料来源: ABS 能源研究2009 作者：佚名光伏产业价值链光伏产业有三个基本组件，构成了价值链，每个相互依存。