Can light and thin glass meet the technical requirements of large-size double glass modules?

  Soon, the author saw an article in the circle of friends, the general idea is: for the current prevailing large-size photovoltaic modules, the 2.0+2.0mm double glass solution cannot meet the safe and reliable technical requirements, and it should be adjusted to the 2.5+2.5mm solution.

  According to the information provided by related companies, the 78pcs version of double glass module based on 182mm battery weighs about 34kg; the 66pcs version of double glass module based on 210mm battery weighs about 38kg, which is the limit for two-person handling. Although some ground power stations can use mechanical auxiliary transportation, in some mountain scenes, these machines are not suitable. If you switch to the 2.5+2.5 solution, the weight of a single component may exceed 45kg, which will bring more difficulties to on-site construction. At the same time, as the glass becomes thicker, the light transmittance of the module and the power generation efficiency of the back side will significantly decrease, which will affect the power generation of the system, which is not desirable.

  Which occasions are glass of different thicknesses used? What are the characteristics of double-glass modules? What are the future development prospects? What kind of packaging scheme should be used for large-size, ultra-high-power photovoltaic modules? On the above issues, the author has discussed with many scholars.

The past and present of double glass modules

Early photovoltaic modules uniformly adopted a single-sided glass + backplane solution, and the glass thickness was not less than 3.2mm. In 2016, some component companies began to promote 2.5+2.5mm double glass components, which were used in special scenarios such as agriculture and light complementation, fishing and light complementation. Later, in order to reduce the price difference between single and double glass and improve the cost performance of double glass modules, the glass thickness of double glass modules was adjusted to 2.0+2.0mm, and it is still used today.

   As the prices of single and double-sided batteries tend to be consistent, double-sided double-glass modules have begun to occupy a higher market share. According to the statistics of the glass industry, in 2018, the proportion of double-sided and double-glass modules was only 8%. By 2020, this value has increased to 23%. She predicts, "By 2025, the market share of bifacial power generation modules will reach 60%, of which the market share of double glass modules will be at least 38%, becoming the main technical route."

   From the feedback of power station investors, double-glass modules have many advantages such as anti-cracking, waterproof vapor transmission, anti-PID light decay, anti-snail pattern, and longer life. With the addition of the aluminum frame, there is no need to worry about the fragmentation of the construction process, and it can also increase the power generation of the photovoltaic system by 10-25% throughout the life cycle, bringing more reliable income to the owner, and it is the first choice for many power station projects.

According to component experts, when the dual-glass technology just emerged, 156.75mm batteries and 60-cell modules were the mainstream products in the market. Even with the all-aluminum frame, it was only 22kg, which did not exceed the handling limit. The industry often started from design, construction, and power generation. Give a positive evaluation from the perspective of quantity and so on. However, with the successive introduction of cell sizes such as 166mm, 210mm, 182mm, and the emergence of 72-cell, 78-cell, and 66-cell product solutions, the weight issue of double glass modules has begun to attract attention.

   In the second half of last year, under the premise that photovoltaic glass was in short supply and prices soared, some component companies launched a single glass + transparent backplane solution from the perspective of reducing product weight and improving supply chain security. However, with the rapid decline of glass prices at the end of the first quarter of 2021, people began to worry about the reliability of organic materials, double-glass modules returned to the mainstream track, and product weight issues were put on the agenda again.

  Sobey believes that it is undoubtedly a good thing for companies to care about labor conditions and reduce the weight of modules, but they must not stick to the rules. In order to meet certain parameters, adjust the glass thickness without sufficient verification. The conditions on the photovoltaic project site are more complicated, and rashly changing the glass thickness may destroy the balance between module weight and reliability. The 2.0mm double glass solution has been verified by the industry for many years. It is recommended to keep it as the industry standard for double glass modules.

  2.0 Double Glass Reliability Research

   Some people in the industry have previously suggested that 3.2mm photovoltaic glass can be fully tempered, but 2.0mm photovoltaic glass can only be semi-tempered. There may be hidden dangers in terms of mechanical strength, wind load, and snow load, and it cannot cope with complex climatic conditions. On this issue, Almaden (SZ:002623) provided us with such experimental data:

   For a piece of photovoltaic glass with a thickness of 2mm, evenly take 72 points on its surface and number them respectively:


The stress test results of these 72 points are as follows:


It can be seen that the stress at different positions of the glass is relatively uniform, and there is no excessive stress gap on a certain side or a certain point.

   After encapsulating the 2.0mm glass into components, the sandbag accumulation test is carried out:


It can be seen that if the bracket is in the middle of the module, the module is basically indistinguishable; if the bracket is on the edge of the module, the module will be deformed to a certain extent, but there is no damage.

At the same time, they also conducted a hail test on the 2.0mm double glass module, impacting the module with an ice ball with a diameter of 25mm at a speed of 23m/s, and then performing an EL test on the module. The results showed that the battery has no cracks and no power. attenuation.


  Judging from the information provided by many component companies, all the officially released large-size, high-power components have been tested by third-party organizations and obtained corresponding certification certificates. Product experts from component companies such as Trina Solar, Risen Energy, Canadian Solar, and other component companies unanimously stated that for newly released ultra-high power modules, whether the beam is perpendicular to the long side or parallel to the long side, the mechanical load can reach 5400Pa at the front , The back of the 2400Pa requirements, meet the technical standards, can be used with confidence.

   From the perspective of glass production, double glass application

   On December 16, 2020, the Ministry of Industry and Information Technology publicly solicited opinions on the "Implementation Measures for Capacity Replacement in the Cement Glass Industry (Revised Draft)", clarifying that photovoltaic rolled glass and automotive glass projects may not formulate capacity replacement plans. Sobi believes that this policy can ease supply tensions to a certain extent, but considering the long period of glass furnace construction and commissioning, and it takes time for production capacity to ramp up, the world glass supply should be treated with caution. According to the prediction of the China Photovoltaic Industry Association, in 2021, the world's new photovoltaic installed capacity is expected to reach 150-170GW, and by 2025, it will reach 270-330GW. For silicon, glass and other links, there is still room for expansion. At least for now, our focus should also be on meeting the needs of the world's photovoltaic projects.

   The aforementioned glass industry experts also pointed out that after the glass thickness is reduced from 2.5mm to 2.0mm, the weight of the module can be reduced by 15%, thereby reducing the cost of packaging, transportation, and installation, and improving the competitiveness of the photovoltaic industry. She emphasized that lower energy consumption, larger size, higher light transmittance, and thinner products are the main trends in the development of the photovoltaic glass industry, which cannot be shaken.

in conclusion

   Whether it is laboratory testing or third-party certification, 2.0mm photovoltaic glass can meet the technical requirements of large-size modules for glass. This solution has been widely used in many photovoltaic projects in the world and has been fully verified. You do not need to worry about the thickness and reliability of the glass.

  According to my country's long-term goal of "carbon peak and carbon neutrality", in the next ten years, the average annual installed capacity of photovoltaic and wind power in the country may exceed 100 million kilowatts. Under the guidance of this ambitious goal, we must take a correct view of the development of the photovoltaic glass industry and encourage the application of various advanced technologies and products, instead of following the old ways and causing waste of resources. Sobi calls on photovoltaic and wind power companies as the main promoters of the "dual carbon" goal to unite, avoid internal attacks, and jointly complete the replacement of traditional fossil energy, build a new power system with new energy as the main body, and improve The level of consumption of photovoltaic and wind power will play an important role in the future energy structure adjustment process to ensure energy security.

Post time: Apr-30-2021