Photovoltaic (solar photovoltaic power generation system), as one of China's seven strategic emerging industries, is an important component of the new energy sector and has an important position in the global energy sector. From 0:00 on June 20 to 24:00 on the 28th, the State Grid Organization of the Qinghai Province was powered by clean energy such as water, wind and light for 9 consecutive days in the province, achieving zero discharge of electricity and rewriting the world record of clean energy supply.
On June 19th, Bloomberg New Energy Finance (BNEF) released the long-term analysis report of the global power system for the new year, “Long-term Outlook for New Energy Markets in 2018â€. The report pointed out that between 2018 and 2050, the global investment in new generation of power generation will reach 11.5 trillion US dollars, of which 8.4 trillion US dollars for wind power and photovoltaics, and 1.5 trillion US dollars for other zero emissions such as hydropower and nuclear power. technology. These investments will increase global PV installed capacity by 17 times and wind power installed capacity by 6 times. From now until 2050, the new photovoltaic power plant's leveling power cost (LCOE) will be reduced by 71%, while onshore wind power LCOE will be reduced by 58%. The LCOE of these two technologies fell by 77% and 41% between 2009 and 2018, respectively.
The development of the photovoltaic industry is naturally inseparable from related equipment. The following are the main equipment: multi-wire cutting equipment, high-purity, low-energy solar-grade polysilicon production equipment, monocrystalline silicon drawing equipment, polycrystalline silicon ingot equipment, high-efficiency battery And component manufacturing equipment, metal organic chemical vapor deposition equipment, epitaxial layer stripping equipment, thin film copper indium gallium selenide absorption layer co-evaporation coating equipment, low-cost high-efficiency atomic layer deposition buffer equipment, continuous roll-to-roll multi-point distributed co-evaporation method Coating equipment, automated integrated chip interconnection equipment, concentrating, flexible, perovskite, organic and other new solar cell manufacturing equipment
As a jewel in the field of new materials, carbon materials are even more popular. Someone predicted that the 21st world will be the carbon era. Let's take a look at the application of carbon materials in the field of photovoltaics.
Application of diamond wire saw in photovoltaic field
Diamond wire for silicon slicing (from the official website of Muller New Materials)
The solar cell must undergo a slicing process during the production process, and the cut silicon wafer is made into a crystalline silicon solar cell through a series of subsequent processes (texturing, etc.). Since the silicon wafer is the main part of the battery, its surface quality and overall performance have a significant impact on the subsequent battery manufacturing process and product quality. At the same time, the silicon wafer is also one of the major components in the battery manufacturing cost. Thinner silicon means lower battery manufacturing costs, which are all related to the silicon wafer cutting process.
The two most important wafer cutting technologies used in the photovoltaic industry today are: mortar wire saw cutting technology and diamond wire saw cutting technology. The main comparisons are as follows:
Mortar cutting and diamond wire cutting
Source: Muller New Materials official website
Although mortar wire saw cutting technology has been widely used in the photovoltaic industry, there are still many unsolved problems. For example, the recovery of silicon chips is difficult, the cutting cost is still relatively high, and the silicon wafer needs to be washed away after cutting, and at the same time, there is Organic substances such as polyethylene glycol may cause environmental pollution if not handled properly.
The use of diamond wire for silicon slicing is much better than traditional cutting methods. The main advantages are as follows:
1. The cutting speed is 2-3 times that of mortar cutting;
2. High return on investment;
3. Increase production capacity without increasing investment;
4. The electricity and water consumption in the production process is lower;
5, no mortar mixing, no need to build a mortar recovery system;
6. Improved total thickness deviation;
7. Improve warpage;
8, the cutting surface quality is good;
9. Good cutting precision 10. Hazardous waste without PEG and SiC;
11, clean and efficient production.
The diamond wire saw cutting technology still uses a multi-wire cutting machine. The difference from the mortar wire saw cutting technology lies in the difference of the cutting lines used. The schematic diagram is as follows. The cutting line used in this technique is an immortal steel wire with a layer of nickel-based alloy or resin on the surface, and the diamond particles are fixed in a nickel-based alloy or resin layer by electroplating, sintering, welding or bonding, that is to say, this technique It is a combination of abrasive and cutting line, which is a two-body cutting when cutting.
Diamond wire saw cutting technology cutting interface schematic
The diamond wire production technology is complicated in technology, involves many fields, and has strict process control. It requires technicians to master the technology of each production process. As a consumable for cutting hard and brittle materials, the diamond distribution density, uniformity and consolidation strength, diamond cutting ability, and fatigue resistance of steel wire directly determine the quality and cost of hard and brittle material slicing. When downstream customers use diamond wire, they have strict requirements on cutting line speed, wire consumption, cutting tension, main cutting speed, cutting time and filming rate. With the advancement of diamond wire cutting technology, its performance requirements and quality stability requirements for diamond wire products are also constantly improving, which also raises the company's production process control, worker technology level, raw material quality and product quality control level. Requirements.
Consolidated abrasive diamond wire saws include both electroplated and resin. Electroplated diamond wire saws have a long production cycle, high cost and high environmental pollution. Resin bond diamond wire saw is a fixed abrasive diamond wire saw formed by fixing the diamond abrasive on the core substrate by heat curing or ultraviolet light and electron beam curing. The resin bond, diamond and filler are mainly used. , the structure of the wire base. Resin bond diamond wire saws are divided into heat-cured diamond wire saws and light-cured diamond wire saws. Compared with the electroplated diamond wire saw, the resin bond diamond wire saw has simple preparation process, short production cycle and low production cost; the damage layer caused by the cutting process is 4~7um, and the electroplated diamond wire is 8~10um, which is favorable for cutting the slice. Improve production rate and reduce environmental pollution.
At present, domestic Müller New Materials (Changsha Mule New Material Technology Co., Ltd.) and Sanchao New Materials (Nanjing Sanchao New Materials Co., Ltd.) are among the best in the electroplated diamond wire saw industry. Among them, Müller's new material focuses on the thinning, line-saving and high-efficiency development of electroplated diamond wire, and has developed a new generation of electroplating equipment and technology. In terms of silicon cutting, it has been upgraded from the 80-day large-scale application of polycrystalline at the beginning of the year to the end of the year. The 70um, single crystal has been upgraded from 75um to 65um, and successfully developed single crystal 60um and polycrystalline 65um series products; in order to consolidate the company's competitive position and leading position in the market.
In addition, in the first quarter of 2018, the company achieved operating income of 143,381,400 yuan, an increase of 168.12% over the same period of the previous year, and the company's products were mainly diamond wire saws; the company's products were mainly in the first quarter of 2018. The total operating income was 138,857,300 yuan, a year-on-year increase of 250.94%. The company's main products include diamond wire (85% or more) and diamond grinding wheel.
Application of graphite and carbon-carbon composite materials in photovoltaic field
The rapid growth of China's photovoltaic power generation capacity and the cost pressure of the photovoltaic industry have brought opportunities for the development of carbon-carbon composite materials. In 2017, China's PV installed capacity exceeded 50GW, a year-on-year increase of more than 43%. By the end of 2017, China's polysilicon production was 240,000 tons, up 23% year-on-year, and import volume was 150,000 tons, up 6.4% year-on-year.
High purity graphite
High purity graphite crucible
High-purity graphite refers to graphite with carbon content greater than 99.99%. It has the advantages of high temperature resistance, corrosion resistance, thermal shock resistance, small thermal expansion coefficient, self-lubrication, small electrical resistivity and easy machining. It is widely used in metallurgy, machinery, and Environmental protection, chemical, electronics, pharmaceutical, military and aerospace industries are increasingly important in the national economy, especially in the photovoltaic industry.
High-purity graphite production process flow chart
Czochralski silicon single crystal furnace and polycrystalline silicon ingot furnace are the main equipments for producing silicon materials in photovoltaic industry. The core components are high purity graphite materials, especially large size isostatic high purity graphite materials. At present, most of the high-purity graphite required for domestic photovoltaic applications needs to be imported, and the amount and specification of graphite are strictly controlled by foreign countries, which restricts the development of the photovoltaic industry. With the development of the photovoltaic industry, traditional graphite materials are also difficult to meet the large-scale needs of Czochralski silicon single crystal furnaces and polycrystalline ingot furnace production equipment. C/C composites have good thermophysical properties, and have great advantages compared with graphite thermal field materials. C/C composite insulation, structural parts and heating elements are Czochralski single crystal furnaces and polycrystals. The development direction of thermal field materials for photovoltaic equipment such as ingot furnaces.
Carbon-carbon composite
Carbon-carbon composite å©åŸš
As is known, carbon fiber composite materials can be classified into resin-based composite materials, metal composite materials, ceramic-based composite materials and carbon-based composite materials according to different substrates, wherein the carbon-based composite material is a carbon-carbon (C/C) composite material. It is a carbon-based composite material reinforced with carbon fiber and its fabric or carbon felt. There are two main methods for its preparation: chemical vapor phase (CVD or CVI) and liquid phase impregnation-carbonization. The former is based on organic low molecular gas precursors, and the latter is based on thermoplastic resins (petroleum pitch, coal pitch, mesophase pitch) or thermosetting resins (furan, furfural, phenolic resin) as precursors. These materials occur at high temperatures. A series of complex chemical changes are converted to matrix carbon.
Carbon-carbon composite process flow chart
C/C composites have the advantages of low density, high strength, high thermal conductivity, low expansion coefficient, good thermal shock resistance and high dimensional stability, making them a few candidate materials for applications above 1650 ° C, the highest theoretical temperature. Up to 2600 ° C, it is considered to be one of the most promising high temperature materials. Compared with traditional graphite materials, C/C composite materials have better insulation performance, higher strength, better toughness, and are not easily broken, which can effectively reduce production energy consumption and increase equipment service life, thereby reducing the cost of the entire production.
The design of C/C composites is very strong, and the reinforcements of any size and shape can be woven according to the needs of the product structure. The applications in the photovoltaic industry mainly include: internal and external thermal insulation cylinders for polysilicon hydrogenation furnaces, U-type heaters. , thermal insulation board, polysilicon ingot furnace cover, enamel protection board, å©åŸš bottom support, insulation board, straight pull silicon single crystal furnace å©åŸš, guide tube, heating element, cover plate, bottom support, internal and external insulation tube.
C/C composite related products
C/C composite materials related standards for photovoltaic industry
At present, C/C composite insulation tubes, heating elements, diversion tubes, and crucibles used in the photovoltaic industry are used in enterprises such as Zhonghuan Photovoltaic, Xi'an Longji, Poly GCL, and Qihui Sunshine. The domestic C/C composite materials production enterprises mainly include Hunan Jinbo Carbon Co., Ltd., Xi'an Supercode Technology Co., Ltd., Aerospace Rui Te Carbon Materials Co., Ltd., Yantai Kaibo Composite Materials Technology Co., Ltd., Hunan Nanfang Boyun. New Materials Co., Ltd., Hunan Jinshi New Materials Co., Ltd., etc., mainly focus on two major fields of photovoltaic (single/polysilicon preparation thermal field) and high temperature heat treatment. Among them, Jinbo Carbon has become a leading enterprise in the domestic C/C composite materials civil field.
According to incomplete statistics, the number of domestic single crystal furnaces has increased to more than 12,000, more than 6,000 polycrystalline silicon ingot furnaces, and about 1,000 reactors and hydrogenation furnaces in the polysilicon manufacturing process, and the thermal field life of the equipment is limited. The cost-effective and excellent performance of C/C composites still has broad market application prospects. In summary, C/C composite thermal field has advantages over graphite thermal field in terms of product performance and cost of use. In a period of time, large size, low cost, high performance, long life C/C composite heat The field is the development direction, and the application of C/C composite products in the photovoltaic industry is beneficial to enterprises to reduce investment costs and improve product quality and competitiveness.
In addition, in the production process of photovoltaic cells, the effect of screen printing will directly affect the conversion efficiency of the battery, and the printing core is the aspect ratio of the silver paste after printing. Therefore, the requirements for screens, silver pastes and scrapers are getting higher and higher. The requirements for the brake line are getting finer and finer, from the initial 60um to the current 30um, even finer; and the lightweight effect of the carbon fiber scraper can be made finer. Carbon fiber rolls can be used in the production and slitting of photovoltaic films. The traditional metal roller has a large weight, a slow start-up speed, and a large inertia. It not only consumes a lot of energy, but also has a large loss of raw materials, which also has a certain impact on production efficiency. The carbon fiber roller has the advantages of being lightweight, not easy to wear, uniform pressure, easy to adjust, and high precision.
Carbon fiber scraper (left) and carbon fiber roller (right)
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