In recent years, driven by the accelerated decline of domestic subsidies and the advancement of photovoltaic technology, the price of polysilicon to modules in the industry chain has accelerated to decline. At the same time, the cost of auxiliary materials such as glass, adhesive film, and backplanes has increased; At the same time, with the improvement of battery module efficiency, the gain of advanced auxiliary material technology to the power generation capacity of the module will also be amplified, and the position of photovoltaic auxiliary materials in the industry chain will be further improved in the future.
1. Photovoltaic glass: a necessity for photovoltaic module packaging, the market growth is better than the installed capacity
Photovoltaic glass mainly refers to ultra-white embossed tempered glass, which is a necessity for module packaging.
Because the thickness of the single solar cell is less than 200μm, the mechanical strength is poor, and it is easy to be damaged; and the electrodes on the surface are easily oxidized and corroded by air and corrosive gases, which cannot meet the severe conditions of long-term outdoor climate change. In other words, dozens of cells (usually 60 and 72 cells) need to be sealed between a photovoltaic glass and an organic back sheet by EVA to form a component, which becomes the smallest unit of a photovoltaic power generation array. If double-sided solar cells are used to realize the double-sided power generation of the module, the back encapsulation material also needs to have the ability to transmit light. Currently, glass or transparent backplanes are generally used.
Therefore, the proportion of photovoltaic glass in the cost of modules has continued to increase. Take a typical 60-type module as an example. The module specifications have basically remained the same over the years. The amount of materials used for monolithic module packaging is generally stable. However, due to different price drops, the cost of glass has increased from 3.7% in the early period to 10.4%. The proportion of monocrystalline components also reached 8.8%. In addition, due to the emergence of dual glass modules, the cost of a single set of modules increased by about 30 yuan, and the total cost of glass further increased to 13%, becoming the highest proportion of non-silicon module costs. Therefore, as module prices continue to drop and glass costs are relatively rigid, photovoltaic glass has become an important part of the value distribution of the photovoltaic industry chain.
2. Features of photovoltaic glass products: high light transmittance and high strength requirements, and calendering process is required
Photovoltaic glass is a type of flat glass. According to the different molding technology, the glass production process can be divided into rolling, grooved vertical lead up, counter-roll (also called asahi method), non-grooved vertical lead up, flat drawing and float method. Among them, float glass is the most important molding process in the glass industry, and float glass accounts for more than 90% of the total global glass output.
Different from ordinary flat glass, photovoltaic glass needs to have the following characteristics: high light transmittance, low absorptivity and reflectivity.
The most important characteristic of photovoltaic glass is its high transmittance. Ordinary glass tends to appear green because of its high iron content, which reduces the transmittance.
Photovoltaic glass generally uses low-iron ultra-white glass, its iron content is less than 1/10 of ordinary glass, and the light transmittance is above 91.5%, while ordinary glass of the same thickness is only 88-89%. According to practical experience, the light transmittance For every 1% increase, the power generation of the module can be increased by about 0.8%.
Photovoltaic modules may face external forces and thermal stress impacts such as wind pressure, snow, hail, and stone throwing during operation. Therefore, toughened glass with high mechanical strength is usually used.
Corrosion resistance, high temperature resistance, low thermal expansion coefficient, etc.
Only ultra-white float glass and ultra-white patterned glass can meet the above-mentioned conditions, and ultra-white patterned glass is the first choice for crystalline silicon battery cover plates. The reason is that, compared with ultra-white float glass, the front surface of photovoltaic glass is treated with different degrees of hazy texture to reduce light reflection, and the reverse surface is treated with a special pattern to greatly enhance the penetration of sunlight at an oblique angle. When the components are installed at an angle, the comprehensive light transmittance of photovoltaic glass is 3%~4% higher than that of ultra-white float glass.
3. The production process of photovoltaic glass: It is mainly divided into two major links: original production and deep processing.
The production of the original film is the core link that reflects the competitiveness; the production of the original film is the untreated semi-finished photovoltaic original film obtained after the five steps of mixing, melting, calendering, annealing and cutting the raw materials; the original film is ground for further processing After the edge is tempered, a tempered sheet is obtained, or tempered + coating is performed to obtain a coated sheet for component packaging.