The photovoltaic cell production plant today are faced with constantly improve production efficiency, improving the efficiency of their products work pressure, another dramatic changes in raw material prices also make it imperative. Affect the production efficiency and product efficacy to improve one of the main problems is the pollution of regular and recurring production environment, surface coating, printing or lamination process before pollution, production efficiency will be a serious impact.
This article will focus on the effects of pollution; major source of pollution problems that may arise; and feasible solutions to reduce the pollution problems.
Pollution impact of solar module production, depending on the production of what kind of solar module. Module production in three ways:
The first generation of solar cell - wafer: dust and pollutants will affect the screen printing process, raises many questions such as 'tombstoning phenomenon', open circuit and short circuit. When the contaminant volatilization and rapid expansion in the soldering point, will result in the weld and dry welding. Followed by solar cells are encapsulated in EVA film, film and battery, dust or pollution particles, blocking the sun, the work efficiency of the final product will reduce.
Even tiny pollution particles invisible to the naked eye, because it will 'tent' effect 'fish eyes' surface pressure in the complex, resulting in defective vision. These are the factory to try to avoid.
Second-generation solar cells - alloy vacuum: it is more efficient, but the surface of the substrate before entering the deposition process must ensure that it is very clear statement. Pollution particles in the connection circuit, there will be the first generation of technology, such as 'fish eye' and 'tombstone'. Similarly, if you want to achieve the best efficiency of battery in the package phase of the glass or film surface must be clean.
The third generation of solar cells using screen printing technology similar to the electronics industry. Usually this type of battery is not the first generation and second generation of efficient, because of pollutants and reduce the efficiency of the problem even more serious. Substrate and templates before each printing step is thorough cleaning. Generally used for screen printing, the substrate is a plastic material or metal foil, these direct from the factory to reach, usually with pollution residues into the substrate before coating or deposition. Plastic film, for example, will normally be based on customer requirements to be cut into different sizes, debris may be left in the surface of the material, the electrostatic attraction of dust is also a serious problem.
The pollution is not just cause problems in the production process. If the pollutant is a conductive material, will cause corrosion of the finished product, is likely only in the latter part of the product, when deposited in the Treasury will be found.
Sources of pollution in the production process come from?
A large number of potential sources of contamination include human hair, fabric fibers, exfoliated epidermis (one of the main source of air dust), ceilings, floors, packaging and bracket, and even called 'non-shedding fibers containing alcoholic substances cleaning cloth will become a source of pollution. 'No loss of fiber' means that the fabric off the surface of the fiber, but when to use it to wipe the battery substrate or template components, the fiber is likely to fall off and left on the clean surface. Static electricity is another major cause of the lead to pollution.
The panels generally by the insulating material, easy to contain electrostatic charge. Therefore, the loose particles will immediately surface of the panels to attract. Transportation to packaging or with a rag to clean the solar panels will generate static electricity. Surface treatment processes, especially in the printing, coated or laminated needs, clean substrate to product quality, reduce waste and downtime, up to increase productivity and corporate profits are vital.
So what to do in order to minimize pollution and the impact of solar cells? How can pollution and static electricity, as well as their impact on production to fight? There are two surface dust, in addition to the static method: non-contact and exposure to dust removal.
Non-contact dust refers to the cleaning equipment is not directly related to being cleaned surface contact, such as vacuuming, blowing dust or ultrasound. Combination of direct contact with the coil mechanical In addition to the static bar and vacuum in order to achieve the effect of dust. If the vacuum system must be evenly distributed over the entire surface of the vacuum force. If the connection is clean material and the poor sealing of the vacuum cleaner, the cleaning effectiveness of the operation will be reduced. The correct location and setting is crucial, at the same speed, width and type of material also be cleaned and vacuum output matching. The drawback is that the working environment around the pollution residual dust removal process of cleaning equipment is activated. Similarly, if the blowing dust, the same to ensure that the surface of blowing dust and air force to be consistent, In addition, the blowing pollution particles or dust is likely to be scattered in other parts of the production line, or surface electrostatic secondary capture . The non-contact type of dust in the removal of moderate pollution (pollutants of about 25 μm) was relatively successful. However, the quality requirements of today's solar cell manufacturing and users continue to improve, because it is difficult to effectively break the pollutants cleaning materials on the surface air layer, can only remove about 25 microns, such a clean performance is clearly not enough. Moving coil or sheet form a layer of air, if you want to achieve a clean and efficient results, we must break with this air layer. Some people believe that the high-pressure air will break through this layer, and then blow on the surface of particles. But in reality, this application does not work. Sources of pollution spreading in the air, and then stay in the other materials after cleaning. Therefore, the traditional non-contact cleaning machines such as ultrasound or air type, because it is unable to break through pollution particles trapped by the surface air layer of clean material, so it is not the most efficient way.
Another option is the use of technology - contact cleaning technology has been confirmed by the semiconductor industry. Contact dust removal technology began in the late 1970s early 1980s, the British Teknek R & D and manufacture the world's first contact cleaner. Contact cleaning is usually clean, dust cleaning roller and the clean surface the physical contact of purpose. Contact cleaning roller is polymer-covered rubber rollers, provide a highly efficient coil and single-Zhang Qingjie way. When the cleaning roller physical contact with the substrate surface contaminants, pollutants transferred to the surface of the cleaning roller. This is the crimp method, the cleaning roller at the same time squeeze the air layer of the substrate surface. Results in a high-speed, high efficiency (96%) to remove micro pollutants (usually less than 10 microns). Unlike brush or mechanical brush cleaning system will scratch the sensitive surface (such as films), the rubber wheel will not damage the surface of the panels. Contact cleaning equipment to remove loose particulate contamination of the surface of the substrate of silicon, glass or EVA film to 1 micron, without damaging the substrate surface. Subsequently cleared of pollution particles transferred to the sticky paper rolls for further analysis and destruction. During the cleaning process, the panels of the cleaned immediately eliminate by electrostatic unit place static to prevent attracting the particles to cause further pollution.
Use contact cleaner, can significantly improve production efficiency and solar cells, the efficacy of the process in every possible surface contamination. Contact cleaning has been proven to be the most efficient surface dust, clean way.
With the continuous increase in raw material prices, the solar cell production plant must find their own to improve production efficiency and reduce waste. Pollutants on the production efficiency and solar battery efficiency have a major impact. Contact cleaning technology to improve production and efficiency of the battery to provide the best alternative solutions.
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