Today's photovoltaic cell manufacturers face pressure to continually improve their production efficiency and product effectiveness. Additionally, drastic changes in commodity prices also make this imperative. One of the main problems affecting production efficiency and improving product efficiency is frequent and recurring pollution in the production environment. If the material surface is contaminated before the coating, printing or laminating process, production efficiency will be seriously affected. Frequent and recurring pollution in the production environment seriously affects production efficiency. Using contact cleaning machines in every process where material surface contamination may occur can significantly improve production and cell efficiency.s solar. This article will focus on the impact of pollution, the main sources of pollution and the problems they can cause and propose feasible solutions to reduce pollution problems. The impact of pollution on the production of solar modules depends on the type of solar module produced. There are three types of modules produced: First generation solar cells – Silicon wafers: Dust and contaminants can affect the screen printing process, causing many problems such as “tombstone phenomenon”, open circuits and short -circuits, etc. When contaminants in solder joints volatilize and expand rapidly, solder leaks and dry solder occur. The solar cell is then encapsulated in EVA film. If there is dust or pollution particles between the film and the cell, the final product will be less effective because il blocks sunlight. Even tiny contamination particles invisible to the naked eye will appear as "fish eyes" on the upset surface due to the "tent effect", resulting in visually defective products. These are things manufacturers should try to avoid. Second Generation Solar Cells – Vacuum Alloys: This is more efficient, but the substrate surface must be very clean before entering the deposition process. If there are contamination particles in the wiring circuit, the same problems as the first generation process will occur, such as "fish eyes" and "tombstones". Likewise, to achieve optimal cellular efficiency, the surface of the glass or film must be cleaned during the conditioning phase. Third generation solar cells use screen printing technology similar to that used in the electronics industry. Thiss batteries are generally less efficient than first and second generation batteries, so the problem of contaminants reducing their efficiency is even more serious. The support and stencil must be carefully cleaned before each printing step. The substrates generally used for screen printing are plastic materials or metal foils. These substrates arrive directly from the manufacturing plant before coating or deposition, and generally contain contaminating residues. For example, plastic films are usually cut into different sizes according to customer requirements. Debris is likely to remain on the surface of the material, and the electrostatic attraction of dust is also a serious problem. Contamination does not only pose problems during production. If the contaminant is a conductive material, it will cause corrosion of the finished product, which will probably not be detected.green until later in the production process, when it is stored in the warehouse. So where do the sources of pollution come from in the production process? A number of potential sources of contamination include human hair, textile fibers, exfoliated epidermis (one of the main sources of airborne dust), ceilings, floors, packaging and shelves, and even alcohol-based cleaning cloths called “non-exfoliated fibers.” become a source of pollution. "No fiber loss" means that the fabric does not lose any fibers from the surface, but when using it to wipe the battery substrate or jig assembly, the fibers may fall off and remain on the surface of the fabric. object to be cleaned. Static electricity is another major cause of pollution. Generally, battery panels are made of insulating materials and easily contain electrosta chargesticks. Free particles are therefore immediately attracted to the surface of the panel. Shipping, unpacking, or cleaning panels with a cloth may generate static electricity. Particularly in processes that require surface treatment such as printing, coating or laminating, a clean substrate is essential to product quality, reducing waste and downtime, and improving manufacturing efficiency. production and company profits. So, what can be done to minimize the impact of pollution on solar cells? How to combat contamination and static electricity and their impact on production? There are currently two methods of surface dusting and static electricity elimination: non-contact and contact dusting. Non-contact dust collection means that the cleaning equipment does not come into direct contact with the surface of the material being cleanedcleaning, such as suction, dust blowing or ultrasonic waves. Combining the static elimination rod and dust collector to directly make mechanical contact with the coil to achieve the effect of dust removal. In the case of a vacuum system, the suction force must be distributed evenly over the entire surface. If the joint connecting the object to be cleaned to the vacuum cleaner is not tight, the effectiveness of the cleaning operation will be reduced. Correct positioning and settings are crucial, as well as the speed, width and type of material being cleaned to match the power of the vacuum. The downside is that contamination residue around the work environment can be activated during the dust collection process of the vacuum equipment. Similarly, if dust is blown, it is also necessary to ensure that the force of the dust blowing air onto the material surface is constant. DAdditionally, blown pollution particles or dust are likely to be dispersed to other locations in the production. Line, or be captured twice by static electricity on the material surface. Non-contact dust collection methods are relatively effective at removing moderate levels of contamination (contaminants around 25 microns). However, nowadays the quality requirements of solar cell manufacturers and users are constantly increasing, because it is difficult to effectively pierce the surface air layer of the material to be cleaned and can only remove about 25 microns of pollutants. Such cleaning performance is obviously. not enough. The moving roller or sheet will form a layer of air. If you want to achieve effective cleaning results, you need to pierce this air layer. Some people think that high pressure air must pass through this layer and blow away particles.are on the surface. But in reality this application does not work. Because the source of contamination disperses in the air then stops at another point on the cleaned material. Therefore, traditional non-contact cleaning machines, such as ultrasonic or airflow machines, are not the most effective method because they cannot break up the contamination particles captured by the surface air layer cleaning material. Another option is to use technology that has proven itself in the semiconductor industry: contact cleaning technology. Contact dusting technology began in the late 1970s and early 1980s. Teknek in the United Kingdom developed and manufactured the world's first contact cleaning machine. Contact cleaning generally uses physical contact between the cleaning roller and the surface of the object being cleaned to achieve thepurpose of cleaning and dusting. Contact Cleaning Rollers are polymer coated rubber rollers that provide an effective way to clean belts and sheets. When the cleaning roller comes into physical contact with contaminants from the substrate surface, the contaminants are transferred to the surface of the cleaning roller. It is In the pinch type method, the cleaning roller simultaneously presses the air layer to the surface of the substrate. The result is highly efficient (over 96%) removal of tiny contaminants (typically less than 10 microns) at high speeds. Unlike brush or mechanical brush cleaning systems which can scratch sensitive material surfaces (like films), rubber rollers will not damage the panel surface. Using contact cleaning equipment can remove loose contamination particles as small asue 1 micron on the surface of substrates such as silicon wafers, glass or EVA films without damaging the substrate surface. The subsequently removed contamination particles are transferred to sticky paper rolls for further analysis and destruction. After the cleaning process, the cleaned battery panels immediately pass through the static elimination unit to eliminate static electricity to avoid recontamination caused by attracted particles. Using contact cleaning machines in every process where material surface contamination may occur can significantly improve production and solar cell efficiency. Contact cleaning has been proven to be the most effective method for dusting and cleaning surfaces. Conclusion As the price of raw materials continues to rise, solar cell manufacturers mustwind find their own methods to improve production efficiency and reduce waste. Contaminants have a significant impact on both production efficiency and the efficiency of the solar cells themselves. Contact cleaning technology offers an optimal alternative solution to increase battery production and efficiency.
What are the pollutions of thin film solar cells?
Crystalline silicon solar cells themselves are not polluted, but the production process is seriously polluted. Crystalline silicon in thin film cells is. Unpolluted and copper indium gallium selenide is not toxic, that is, cadmium telluride is toxic, but the cadmium in the battery is in an ionic state and has a low toxicity. Levels of cadmium detected in urine samples from manufacturer employees were equalsafely.
Thin-film photovoltaic cells are deposited on glass, plastic, stainless steel and other low-cost substrates to form very thin photosensitive materials to achieve photoelectric conversion. They mainly include thin film cells of silicon (a-si, a-si/c- si
etc.), cadmium telluride (cdte), copper, indium and gallium selenide (cigs).
The packaged thin film solar cell itself has no pollution, but there is pollution during the refining of production materials. For example, there is pollution during the refining of silicon materials.
In addition, some thin film battery materials are inherently polluting. For example, cadmium can cause severe liver and kidney damage, pneumonia, pulmonary edema and death in industrial toxicology. Therefore, firstsolar, the largesthe global cadmium telluride thin film battery company, has implemented a recovery and recycling plan for prepaid photovoltaic modules due to the cadmium pollution problem. That is, any customer who purchases firstsolar solar modules can use them in the module on request. for end-of-life recycling, first
solar will cover the costs of recovery and recycling of these products.