Silicone For Packaging Solar Power Battery
Author: Source: Datetime: 2016-09-12 15:38:15
Organic silicon film in the heat, air, moisture and other aging conditions, silicone side groups can easily be oxidized to side reactions or side chain coupling macromolecular organic free radicals, so that the physical properties change dramatically such as Si-0 bond to react with water to make the air-strand breaks and aging. Under the action also be interpreted as due to oxygen and water, the hydrolysis of silicon forming the silanol structure Si (OH) 2, leading to a silicon atom of the surrounding chemical environment changes Therefore, the solar battery module encapsulated with the silicone required to join suitable additives improve the aging performance.
Standard solar cell module in general to join the two EVA film, EVA film between the battery and glass, batteries and TPT from bonding effect.
(1) EVA film profile
EVA is ethylene and vinyl acetate copolymer, EVA resin and polyethylene (PE) compared to the molecular chain t since the introduction of the vinyl application • body (VA), from 'while reducing the degree of crystallinity, mention Gao transparent , flexibility, impact resistance, heat sealability and improved its unmodified EVA transparent, soft, hot melt adhesive, low melting temperature (less than 80 ° C), and good melt flow. These features meet the requirements of solar cell package, but its poor heat resistance, easy to extend and elasticity, low cohesive strength, easy to make solar thermal shrinkage caused fragmentation, the adhesive delamination. In addition, the solar cell module as a long-term outdoor use of products, EVA film whether it can withstand outdoor UV and heat aging also manufacturers and users are very concerned about heart problems. Unmodified EVA such as prolonged exposure to ultraviolet light and the influence of heat, easy to crack, discoloration, easy to fall off from the glass, TPT, thereby greatly reducing the efficiency of solar cells and shorten its life but use lifePo4 batteries life is longer, and ultimately increase the solar cell cost, is not conducive to the promotion and application of solar cells. Therefore, the need to be modified EVA.
EVA film on the major pieces of change in two ways: on the one hand, during the preparation of the EVA film by experimental design and selection, add appropriate, make polymer stabilizing additives, such as ultraviolet light absorbers, UV stabilizers, heat stabilizers, thereby significantly effective in improving resistance to weather aging properties of EVA film; on the other hand, the use of chemical crosslinking mention Gao EVA film heat resistance, and reduce its heat-shrinkable, the organic peroxide crosslinking agent is added in the formulation of EVA film, EVA film when heated to a certain temperature, crosslinking agents decompose to generate free radicals to initiate the reaction between macromolecules, solar pwoer generation forming a three-dimensional network structure to EVA layer crosslinking ⑷. In general, when the degree of crosslinking (EVA refers to macromolecules after the crosslinking reaction to the extent insoluble gel cured) is greater than 60%, EVA film can withstand atmospheric changes, no longer appear much Shrink , encapsulation of solar cells to meet the needs.
EVA as raw material, adding suitable additives such as modified by heat extrusion molding prepared EVA film solar batteries at room temperature without stickiness, easy cutting operation; when in use, according to the solar heat curing conditions battery components laminated packaging, cooling after creating a permanent seal bonding.
EVA solar film has been widely used in solar battery encapsulation, sealing electrical and electronic components, car decoration and so on. It is environmentally friendly, resistant to UV aging, etc., can replace epoxy resin.
(2) EVA film solar cell key performance indicators
Generally, EVA film for solar battery encapsulation must meet the following key performance indicators.
① type fast curing conditions, heated to 135℃, constant temperature 15-20min; slow type, heated to 145℃, constant temperature 30-40min.
② thickness 0.3~0.8mm; width: 1100mm, 800mm, 600mm and other specifications.
③ EVA film properties after cured encapsulation requires solar transmittance greater than 90%; degree of crosslinking is greater than 65%; Peel Strength (N/cm), the glass/film is greater than 30; TPT/film is greater than 15; temperature resistance: high temperature 80X :, a low temperature 40 ℃, better dimensional stability; has good resistance to UV aging properties.
Most of the current domestic solar power battery encapsulation EVA film, although able to achieve the key performance indicators, but its anti-aging properties, particularly resistant to light embroidered banner outside the aging properties have not done systematic and thorough study. Major Gaps foreign Jiong products is reflected in the anti-aging properties. solar power generator In response to this situation, the recent South China Polytechnic University and the Chinese Academy of Sciences Guangzhou Institute of Energy cooperation, more systematic and in-depth study of the solar cell module to improve the life of critical packaging materials EVA film. Developed by the EVA film in addition to fully satisfy the above key performance indicators, but also with a more excellent anti-aging properties, solar power generation especially resistance to UV aging properties. After having detected through measurement recognized inspection department, developed the EVA film according to GB/T 16422.3- 1997 standard aging test of 1000h. Specific test conditions: I type UVA - 340 lamp, irradiance68°; cycling conditions: black standard temperature of 70℃ under irradiation exposure 8h; then condensing temperature of 68 degrees in the black mark at 50℃ exposure 4h. Under these conditions, after 1000h aging, changes in yellowness index developed by the EVA film EVA film is much lower than the current domestic market, relatively close to the foreign imports of similar products; while prices than imported EVA film to much lower. The findings improve the life of the solar cell module, reducing its cost which is importane for portable solar power genertaor, the promotion of solar energy renewable clean energy to promote the application and development is very meaningful.
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