Dual glass photovoltaic module and method of making same

Abstract

The application provides a double-glass photovoltaic module and a preparation method thereof, and belongs to the technical field of photovoltaics. The double-glass photovoltaic module comprises a cell string layer, a first encapsulation structure and a second encapsulation structure. The first encapsulation structure is located on the light-receiving surface of the cell string layer and has a first optical filtering characteristic. The first optical filtering characteristic comprises blocking and / or converting the UVC waveband and the UVB waveband, and transmitting the UVA waveband and the visible light and above waveband. The second encapsulation structure is located on the light-irradiated surface of the cell string layer and has a second optical filtering characteristic. The second optical filtering characteristic comprises blocking and / or converting the ultraviolet waveband, and transmitting the visible light and above waveband. The application can effectively reduce the initial power loss while ensuring that the double-glass photovoltaic module passes the most stringent UV60 test.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, specifically to a double-glass photovoltaic module and its preparation method. Background Technology

[0002] Back-contact (BC) double-glass photovoltaic (PV) modules have become a key choice in the high-end PV market due to their high conversion efficiency, high reliability, and elegant appearance. However, in practical applications and reliability testing, especially in the UV60 (60 kWh / m² ultraviolet radiation) test specified by the International Electrotechnical Commission (IEC) standard 61215, BC double-glass PV modules generally exhibit greater power degradation than conventional PV modules, typically reaching 3% to 4%, exceeding the industry-expected threshold of 3%. The root cause of this problem lies in the lack of a backsheet in double-glass PV modules; neither the front nor back glass can effectively block ultraviolet radiation, resulting in both sides of the cells being exposed to ultraviolet radiation simultaneously. Therefore, improvements to double-glass PV modules are urgently needed. Summary of the Invention

[0003] In view of this, the embodiments of this application aim to provide a double-glass photovoltaic module and its preparation method to solve the problem of excessive ultraviolet degradation in existing double-glass photovoltaic modules.

[0004] This application provides a double-glass photovoltaic module, including: Battery stacking; A first packaging structure is located on the light-facing side of the battery string layer. The first packaging structure has a first optical filtering characteristic, which includes blocking and / or converting the UVC and UVB bands, and transmitting the UVA band and visible light and above. The second packaging structure is located on the back surface of the battery string layer. The second packaging structure has a second optical filtering characteristic, which includes blocking and / or converting the ultraviolet band and transmitting visible light and above.

[0005] In some embodiments, the transmittance of the first packaging structure to the UVA band is less than the transmittance of the first packaging structure to the visible light and above bands. And / or, the transmittance of the first packaging structure to the UVA band is less than the transmittance of the second packaging structure to the visible light and above bands.

[0006] In some embodiments, the blocking rate of the first packaging structure for the UVC and UVB bands is less than the blocking rate of the second packaging structure for the ultraviolet band. And / or, the transmittance of the first packaging structure to the visible light and above wavelengths is greater than the transmittance of the second packaging structure to the visible light and above wavelengths.

[0007] In some embodiments, the first encapsulation structure has a blocking rate of 95% or greater for the UVC and UVB bands; And / or, the transmittance of the first encapsulation structure to the UVA band is 20%~60%; And / or, the first packaging structure has a transmittance of 93% or more for visible light and above wavelengths; And / or, the second packaging structure has a blocking rate of 99% or greater for the ultraviolet band; And / or, the second packaging structure has a transmittance of 85% or more for visible light and above.

[0008] In some embodiments, both the first packaging structure and the second packaging structure have at least two stacked packaging layers, each of the packaging layers of the first packaging structure has the first optical filtering characteristic, and each of the packaging layers of the second packaging structure has the second optical filtering characteristic.

[0009] In some embodiments, the at least two stacked encapsulation layers of the first encapsulation structure and / or the second encapsulation structure are both two layers, namely a glass layer and an encapsulating adhesive layer, wherein the encapsulating adhesive layer is closer to the battery string layer than the glass layer; Alternatively, the at least two stacked encapsulation layers of the first encapsulation structure and / or the second encapsulation structure are all three layers, namely a glass layer, an optical filter layer and an encapsulating adhesive layer, wherein the encapsulating adhesive layer is closer to the battery string layer than the glass layer, and the optical filter layer is located between the glass layer and the encapsulating adhesive layer.

[0010] In some embodiments, a first ultraviolet absorber is added to any of the encapsulation layers of the first encapsulation structure, and a second ultraviolet absorber is added to any of the encapsulation layers of the second encapsulation structure. The amount of the second ultraviolet absorber added is greater than the amount of the first ultraviolet absorber added, and / or the mass of the first ultraviolet absorber added is 0.1% to 0.5% of the mass of the matrix material of the corresponding encapsulation layer.

[0011] In some embodiments, the battery string layer is a back-contact battery string layer.

[0012] This application also provides a method for preparing a double-glass photovoltaic module, comprising: A battery string layer is placed on a second packaging structure, the back surface of the battery string layer is attached to the surface of the second packaging structure, and the second packaging structure has a second optical filtering characteristic, which includes: blocking and / or converting the ultraviolet band and transmitting visible light and above. The first encapsulation structure is placed on the light-facing side of the battery string layer. The first encapsulation structure has a first optical filtering characteristic, which includes: blocking and / or converting the UVC and UVB bands, and transmitting the UVA band and visible light and above; and; The first packaging structure, the battery string layer, and the second packaging structure are laminated together.

[0013] In some embodiments, both the first encapsulation structure and the second encapsulation structure include a glass layer and an encapsulating adhesive layer, wherein the encapsulating adhesive layer is closer to the battery string layer than the glass layer, and the encapsulating adhesive layer has the first optical filtering characteristic or the second optical filtering characteristic; and The first encapsulation structure, the battery string layer, and the second encapsulation structure are laminated together in two stages. The lamination temperatures are 120℃ to 150℃, with the first lamination temperature being lower than the second. The vacuum level for the first lamination is -70 kPa to -30 kPa, and the lamination time is 123 s to 126 s. The vacuum level for the second lamination is -70 kPa to -50 kPa, and the lamination time is 458 s to 462 s.

[0014] This application provides a double-glass photovoltaic module and its fabrication method. The double-glass photovoltaic module includes a cell string layer, a first encapsulation structure, and a second encapsulation structure. The first encapsulation structure is located on the light-facing side of the cell string layer and has first optical filtering characteristics, including blocking and / or converting UVC and UVB bands while transmitting UVA and visible light and above. The second encapsulation structure is located on the back-facing side of the cell string layer and has second optical filtering characteristics, including blocking and / or converting ultraviolet bands while transmitting visible light and above. On the one hand, the first encapsulation structure can block and / or convert short-wave ultraviolet light that is not beneficial to power generation, while allowing long-wave ultraviolet light and visible light and above that are beneficial to power generation to pass through. This achieves precise filtering and maximizes the utilization of light waves, preserving power generation benefits to the greatest extent and providing a certain degree of ultraviolet protection. On the other hand, the second encapsulation structure can block and / or convert ultraviolet light incident from the back surface, achieving the effect of blocking ultraviolet light incident from the back surface. This provides good ultraviolet protection for the cell passivation layer, preventing excessive ultraviolet degradation of the double-glass photovoltaic module. It also protects the cell string and enhances the anti-ultraviolet aging capability of the second encapsulation structure itself, reducing the risks of yellowing, delamination, etc., and comprehensively improving the long-term outdoor durability and power generation life of the double-glass photovoltaic module. This asymmetric ultraviolet protection strategy can achieve the best balance between reliability (low ultraviolet degradation) and economy (high initial power), thereby ensuring that the double-glass photovoltaic module passes the most stringent UV60 test while effectively reducing initial power loss. Furthermore, the double-glass photovoltaic module in this application has a simple structure, is easy to implement, does not change the existing stacked structure and production process of double-glass photovoltaic modules, is easy to implement, does not require additional equipment or complex processes, has low implementation cost, and is easy to scale up production and promote. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the layered structure of a double-glass photovoltaic module provided in an embodiment of this application.

[0016] Figure 2 for Figure 1 A schematic diagram of the structure of the double-glass photovoltaic module along the AA direction.

[0017] Figure 3 This is a flowchart illustrating a method for preparing a double-glass photovoltaic module according to an embodiment of this application.

[0018] The attached figures are labeled as follows: 100 - Battery string layer; 100a - Light-facing surface; 100b - Backlight-facing surface; 200 - First encapsulation structure; 201 - First glass layer; 202 - First encapsulating adhesive layer; 300 - Second encapsulation structure; 301 - Second glass layer; 302 - Second encapsulating adhesive layer. Detailed Implementation

[0019] The applicant conducted multiple experiments and found that when two identical BC double-glass photovoltaic modules were subjected to UV60 testing, one module was tested normally while the other had its back glass completely covered with opaque black tape, the power degradation of the module that was tested normally was 3.55%, while the power degradation of the module with its back glass completely covered with opaque black tape was only 2.95%. The experiment shows that for BC double-glass photovoltaic modules, ultraviolet light incident from the back surface is the main reason for excessive UV degradation (UV power degradation greater than 3%). The underlying principle may be that because the BC cell has no grid lines on the front and a segmented area on the back, chemical bonds such as Si-N bonds, Si-H bonds, and O-AL bonds in the cell passivation layer are easily damaged by ultraviolet light.

[0020] There are currently two solutions to address the issue of UV power degradation in BC double-glass photovoltaic modules.

[0021] The first approach is to replace the conventional encapsulating film with a UV-blocking film, meaning that the same high-cutoff-rate UV-blocking film (blocking all UV wavelengths) is used on both the front and back of the BC double-glass photovoltaic module. This approach achieves this by uniformly adding a UV absorber to the substrate material of the encapsulating film. The basic working principle is that the UV absorber effectively absorbs photon energy in the UV band, thus preventing ultraviolet rays from penetrating the encapsulating film and reaching the surface of the solar cells. This approach is applicable primarily because it provides relatively balanced UV protection for both the sun-facing and back-facing sides of the cells, helping to slow down UV aging and prevent excessive UV degradation. However, this approach indiscriminately blocks all UV wavelengths, leading to unnecessary losses in the initial power output of the BC double-glass photovoltaic module and sacrificing its high efficiency advantage.

[0022] The second approach is to replace the conventional encapsulating film with an ultraviolet conversion film to convert ultraviolet light into visible light. This approach has a positive effect on improving initial power, but its performance is not ideal when applied to BC double-glass photovoltaic modules that are particularly sensitive to ultraviolet light from the back side. This is because the passivation layer of the cells in BC double-glass photovoltaic modules is usually extremely sensitive to certain short-wave ultraviolet light, and the ultraviolet protection capability of the ultraviolet conversion film is insufficient, so long-term reliability risks still exist.

[0023] Therefore, a fundamental contradiction lies in the fact that when providing the same level of UV protection to the back surface of the battery as to the front surface, its inherent design will inevitably block UV wavelengths that are incident from the front surface and have the potential to contribute to power generation, resulting in unnecessary loss of initial power of the BC double-glass photovoltaic module. On the other hand, if a UV conversion film is used to pursue high initial power, insufficient UV protection may lead to excessive UV degradation or reduced reliability. The root causes of the above contradiction are multifaceted: from the perspective of optical function allocation, a symmetrical and indiscriminate spectral management strategy is adopted for both the front and back surfaces of the BC double-glass photovoltaic module, failing to make targeted designs based on the differences in the effects of incident light on the front and back surfaces and the battery damage mechanisms; from the perspective of light energy utilization efficiency, a strategy of completely blocking the UV wavelengths on both the front and back surfaces also blocks UV wavelengths that could be utilized by the battery, resulting in wasted light energy. These factors together make it difficult to achieve a balance between pursuing high UV protection and high initial power.

[0024] Based on this, this application proposes a double-glass photovoltaic module and its fabrication method. The core concept is to set a first encapsulation structure and a second encapsulation structure with different optical filtering characteristics on the light-facing and back-facing sides of the cell string layer, respectively, to differentiate the spectrum and allocate functions of the light-facing and back-facing sides of the double-glass photovoltaic module. This effectively enhances the ultraviolet protection of the back-facing side and improves the overall light energy utilization rate without significantly sacrificing the high light transmittance of the light-facing side. In other words, it provides an optically asymmetric encapsulation structure to solve the contradiction between excessive power attenuation and initial power loss in the UV60 test of the double-glass photovoltaic module, and achieves synergistic optimization of high reliability, high power generation performance and low ultraviolet attenuation.

[0025] Specifically, the double-glass photovoltaic module includes a cell string layer, a first encapsulation structure, and a second encapsulation structure. The first encapsulation structure is located on the light-facing side of the cell string layer and has a first optical filtering characteristic, which includes blocking and / or converting the UVC and UVB bands while allowing the UVA band and visible light and above to pass through. The second encapsulation structure is located on the back-facing side of the cell string layer and has a second optical filtering characteristic, which includes blocking and / or converting the ultraviolet band while allowing the visible light and above to pass through. On the one hand, the first encapsulation structure can block and / or convert short-wave ultraviolet light that is not beneficial to power generation, while allowing long-wave ultraviolet light and visible light and above that are beneficial to power generation to pass through, achieving precise filtering and maximizing the utilization of light waves, thus preserving the power generation benefits to the greatest extent. On the other hand, the second encapsulation structure can block and / or convert ultraviolet light incident from the back surface, achieving the effect of blocking ultraviolet light incident from the back surface. It can also provide a certain degree of protection for the cell passivation layer, preventing the ultraviolet degradation of the double-glass photovoltaic module from exceeding the standard. It can also protect the cell string and enhance the anti-ultraviolet aging capability of the second encapsulation structure itself, reducing the risks of yellowing, delamination, etc., and comprehensively improving the long-term outdoor durability and power generation life of the double-glass photovoltaic module. This asymmetric ultraviolet protection strategy can achieve the best balance between reliability, low ultraviolet degradation, and high initial power, thereby ensuring that the double-glass photovoltaic module passes the most stringent UV60 test while effectively reducing initial power loss. Furthermore, the double-glass photovoltaic module in this application has a simple structure, is easy to implement, does not change the existing stacked structure and production process of double-glass photovoltaic modules, is easy to implement, does not require additional equipment or complex processes, has low implementation cost, and is easy to scale up production and promote.

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] Figure 1 This is a schematic diagram of the structure of a double-glass photovoltaic module provided in one embodiment of this application. Figure 2 for Figure 1 A schematic diagram of the structure of a double-glass photovoltaic module along the AA direction. (See diagram below.) Figure 1 and Figure 2 As shown, the double-glass photovoltaic module includes a cell string layer 100, a first encapsulation structure 200, and a second encapsulation structure 300.

[0028] Specifically, the cell string layer 100 comprises multiple interconnected photovoltaic cells, which are the core power generation units of the double-glass photovoltaic module, used to convert light energy into electrical energy. In some embodiments, these photovoltaic cells can be conventional PERC cells, TOPCon cells, or heterojunction cells. In a preferred embodiment, the photovoltaic cells can be BC cells, with all electrodes of the BC cells arranged on the back surface 100b of the cell. This results in the light-facing surface 100a being free of any metal grid lines, providing a larger light-receiving area and aesthetic value. However, the back surface 100b of this structure integrates all electrodes and a complex cell passivation layer. These layers are highly sensitive to short-wave ultraviolet light and are easily damaged, leading to performance degradation. Therefore, providing differentiated spectral management tailored to the characteristics of BC cells has particularly significant technical benefits, which will be explained below.

[0029] Furthermore, the first packaging structure 200 and the second packaging structure 300 together constitute the packaging protection system of the battery string layer 100, which mainly undertakes functions such as optical transmission, electrical insulation, mechanical bonding and environmental barrier.

[0030] The first encapsulation structure 200 is located on the light-facing surface 100a of the cell string layer 100. The first encapsulation structure 200 has first optical filtering characteristics, including blocking and / or converting UVC and UVB bands, while allowing UVA bands and visible light and above to pass through. One purpose of the first encapsulation structure 200 is to filter sunlight incident from the light-facing surface 100a, blocking and / or converting high-energy, highly destructive short-wavelength (UVC and UVB bands) light that contributes very little to the current mainstream crystalline silicon cell power generation, while allowing long-wavelength (UVA band) ultraviolet light and the main visible light and above bands to pass through, thus achieving precise filtering and maximum utilization of light waves while providing basic ultraviolet protection, preserving power generation benefits to the greatest extent, and ensuring high initial power of the module.

[0031] It should be noted that the UVA band is the long-wave band of the ultraviolet band, and the wavelength of light in the UVA band can be 315nm~400nm. The UVC band and UVB band are the short-wave bands of the ultraviolet band, and the wavelength of light in the UVB band can be 280nm~315nm, and the wavelength of light in the UVC band can be 100nm~280nm. The visible light and above bands can include the visible light band and the near-infrared band. The wavelength of light in the visible light band can be 380nm~780nm, and the wavelength of light in the near-infrared band can be 780nm~1100nm. Those skilled in the art will know that there may be slight conventional variations in these ranges.

[0032] In some embodiments, blocking UVC and UVB bands can refer to absorbing or reflecting UVC and UVB bands. Absorbing UVC and UVB bands converts the light energy of UVC and UVB bands into heat energy, which can be achieved by adding ultraviolet absorbers (such as benzotriazole or triazine ultraviolet absorbers). Reflecting UVC and UVB bands shifts the light path of UVC and UVB bands, which can be achieved by adding highly reflective nano-inorganic particles (such as titanium dioxide, zinc oxide, or glass crystals), constructing polymer multilayer films (PMF), or preparing micro-nano structures. Converting UVC and UVB bands refers to converting short-wavelength UVC and UVB band light into long-wavelength light (such as converting it into visible light of 450nm~550nm), which can be achieved by adding light conversion materials (such as phosphors or quantum dots). Therefore, blocking and / or converting UVC and UVB bands can include at least one of reflecting UVC and UVB bands, absorbing UVC and UVB bands, and converting UVC and UVB bands.

[0033] In some embodiments, the first packaging structure 200 has at least two stacked packaging layers, and any one of the packaging layers of the first packaging structure 200 has a first optical filtering characteristic.

[0034] In one specific implementation, the first encapsulation structure 200 has at least two stacked encapsulation layers, namely a glass layer and an encapsulating adhesive layer. The encapsulating adhesive layer is closer to the battery string layer 100 than the glass layer. That is, the encapsulating adhesive layer and the glass layer of the first encapsulation structure 200 are stacked sequentially on the light-facing surface 100a of the battery string layer 100. At this time, either the encapsulating adhesive layer or the glass layer can have the first optical filtering characteristics. This means that the first optical filtering function can be integrated into any layer of the first encapsulation structure 200, which improves the flexibility and reliability of implementation. Even if the main function of a certain layer is not filtering (such as the glass layer mainly providing mechanical strength), it can still have or not destroy the filtering characteristics required by the whole.

[0035] For ease of description, the encapsulating adhesive layer and glass layer of the first encapsulation structure 200 are referred to as the first encapsulating adhesive layer 202 and the first glass layer 201, respectively. For example, the first glass layer 201 can provide the main mechanical support and protection, while the first optical filtering characteristic can be mainly achieved by the first encapsulating adhesive layer 202. In this case, specific types and amounts of additives (such as ultraviolet absorbers) can be added to the first encapsulating adhesive layer 202 to achieve the first optical filtering characteristic. This approach utilizes mature film processing and lamination processes, facilitating industrial implementation, and allows for flexible and precise control of its spectral characteristics by adjusting the film formulation. Alternatively, the first glass layer 201 can provide the main mechanical support and protection, while also achieving the first optical filtering characteristic. In this case, specific types and amounts of additives (such as ultraviolet absorbers) can be added to the first glass layer 201 to achieve the first optical filtering characteristic. This design offers greater design freedom.

[0036] In one specific implementation, the at least two stacked encapsulation layers of the first encapsulation structure 200 may also have three layers: a glass layer, an optical filter layer, and an encapsulating adhesive layer. The encapsulating adhesive layer is closer to the battery string layer 100 than the glass layer, and the optical filter layer can be located between the glass layer and the encapsulating adhesive layer. That is, the encapsulating adhesive layer, the optical filter layer, and the glass layer of the first encapsulation structure 200 are stacked sequentially on the light-facing surface 100a of the battery string layer 100. In this case, the first optical filtering characteristic can be achieved by the optical filter layer. Specific types and amounts of additives (such as ultraviolet absorbers) can be added to the optical filter layer to achieve the first optical filtering characteristic. Of course, the optical filter layer, as an independent functional film, such as a multilayer dielectric interference filter film or a polymer film doped with special ions, is specifically responsible for achieving complex or precise spectral control. The encapsulating adhesive layer mainly undertakes the functions of adhesion and encapsulation protection, while the glass layer still provides basic support. This method is particularly suitable when the required optical filtering curve is very special and difficult to achieve with conventional film additive formulations.

[0037] Generally, the first encapsulation structure 200 can achieve the first optical filtering characteristics in various ways. For example, it may include, but is not limited to: a combination of special glass (such as cerium-containing glass) with inherent filtering characteristics and a transparent film; or a three-layer structure consisting of ordinary ultra-white photovoltaic glass, an independent optical filtering functional film, and a film; or a composite of multiple structural layers with gradient filtering characteristics. These solutions can all achieve the above-mentioned function of blocking and / or converting the UVC and UVB bands, and allowing the UVA band and visible light and above to pass through. Specific means to achieve the above-mentioned spectral selection function can include: at the material level, it can be achieved by incorporating ultraviolet absorbers with sharp absorption cutoff functions, such as benzotriazoles and triazines, into the matrix material (such as polyolefin elastomer POE, co-extruded ethylene-vinyl acetate copolymer EVA, resin or cross-linked polyolefin elastomer POE), or by incorporating light conversion materials into the matrix material, or by incorporating high reflective materials into the matrix material; at the structural level, it can be achieved by designing photonic crystal thin films with specific refractive index periodic structures to achieve reflective blocking of specific wavelength bands, etc., which will not be illustrated here.

[0038] In one specific embodiment, a benzotriazole-based UV absorber can be added as a first UV absorber to any encapsulation layer (such as within the first encapsulating adhesive layer 202) of the first encapsulation structure 200. The added mass can be 0.1% to 0.5% of the mass of the matrix material of the corresponding encapsulation layer, ensuring uniform distribution after lamination without migration or precipitation. By controlling the amount of the first UV absorber and the dispersion process, the first encapsulating adhesive layer 202 can achieve extremely low transmittance below the UVB band, controllable transmittance in the UVA band, and extremely high transmittance in the visible light and above bands. Those skilled in the art will understand that the type of UV absorber is not limited to this; other highly efficient UV absorbers such as hydroxyphenyltriazine can also be used, and the matrix material can be replaced with other polymer materials. The specific value of the added amount of the first UV absorber can be optimized and adjusted within the above range according to the required cutoff wavelength and transmittance curve.

[0039] In some embodiments, the thickness of the first encapsulating adhesive layer 202 can be 0.4mm to 0.6mm, for example, 0.5mm.

[0040] Furthermore, the second encapsulation structure 300 is located on the back surface 100b of the cell string layer 100. The second encapsulation structure 300 has a second optical filtering characteristic, which includes blocking and / or converting the ultraviolet band while allowing visible light and higher bands to pass through. One of the purposes of the second encapsulation structure 300 is to implement a comprehensive ultraviolet light blocking strategy for sunlight incident from the back surface 100b, aiming to eliminate the threat of all ultraviolet light bands to the back surface 100b, especially protecting the passivation film layer of the BC cell back surface 100b, thereby fundamentally solving the problem of excessive ultraviolet degradation of the module; at the same time, it allows visible light and higher bands to pass through, thus not hindering the double-glass photovoltaic module from utilizing the visible light and higher bands incident from the back surface 100b to maintain bifacial power generation characteristics.

[0041] In some embodiments, blocking the ultraviolet band can refer to absorbing or reflecting the entire ultraviolet band. Absorbing the ultraviolet band converts the light energy of the ultraviolet band into heat energy, which can be achieved by adding ultraviolet absorbers (ultraviolet absorbers composed of benzotriazole and hindered amine light stabilizers (HALS)). Reflecting the ultraviolet band shifts the light path of the ultraviolet band, which can be achieved by adding nano-inorganic particles with high reflectivity across the entire ultraviolet band (such as titanium dioxide, zinc oxide, or glass crystals), constructing polymer multilayer films (PMF), or preparing micro / nano structures. Converting the ultraviolet band refers to converting short-wavelength ultraviolet light into long-wavelength light (such as converting it into visible light of 450nm~550nm), which can be achieved by adding light conversion materials (such as phosphors or quantum dots). Therefore, blocking and / or converting the ultraviolet band can include at least one of reflecting the ultraviolet band, absorbing the ultraviolet band, and converting the ultraviolet band.

[0042] The second encapsulation structure 300 is implemented similarly to the first encapsulation structure 200, and may also have at least two stacked encapsulation layers. Each encapsulation layer of the second encapsulation structure 300 has a second optical filtering characteristic. For example, the second encapsulation structure 300 can also be implemented as a two-layer structure consisting of a glass layer and an encapsulating adhesive layer. For ease of description, the encapsulating adhesive layer and the glass layer of the second encapsulation structure 300 are referred to as the second encapsulating adhesive layer 302 and the second glass layer 301, respectively. The second optical filtering characteristic can be mainly or entirely carried by the second encapsulating adhesive layer 302 or the second glass layer 301.

[0043] In a specific example, the second glass layer 301 can be made of the same ordinary ultra-white photovoltaic glass as the first glass layer 201, and the matrix material of the second encapsulating layer 302 can also be polyolefin elastomer (POE) or polyethylene foam (EPE) to ensure similar processing performance and aging shrinkage rate as the first encapsulating layer 202, avoiding stress after lamination. To achieve efficient blocking of the entire ultraviolet band, a compound ultraviolet absorber is added to the second encapsulating layer 302 as a second ultraviolet absorber. The second ultraviolet absorber can typically be a synergistic combination of benzotriazole and hindered amine light stabilizers (HALS). HALS can effectively capture free radicals generated during the aging process of the film, significantly improving the film's own resistance to ultraviolet aging.

[0044] Furthermore, to achieve full UV blocking, the amount of the second UV absorber can be higher than that of the first UV absorber. For example, the amount of the second UV absorber can be greater than 0.5% of the matrix material mass. The specific amount can be determined experimentally. This difference in the amount of absorber is a direct and effective technical means to achieve "stronger protection on the back side 100b than on the front side 100a" in terms of optical properties. By simply controlling the proportion of additives, films with different UV blocking capabilities can be derived in the same matrix material system, thereby precisely matching different UV protection requirements and ensuring that the UV power attenuation of the double-glass photovoltaic module is less than 3%.

[0045] Specifically, the addition mass of the first UV absorber can be limited to 0.1% to 0.5% of the mass of the substrate material of the corresponding encapsulation layer. This range is an optimal range verified through extensive experiments. It can achieve efficient blocking of the frontal UVC / UVB bands (blocking rate ≥95%) while ensuring appropriate transmittance of the UVA band (transmittance 20% to 60%), and does not affect the high transmittance of visible light and above (transmittance ≥93%). The addition amount of the second UV absorber needs to be greater than that of the first UV absorber to ensure stronger full-band UV blocking capability (blocking rate ≥99%). For example, the addition amount of the second UV absorber can be 0.6% to 2.0% of the mass of its substrate material.

[0046] In a specific formulation example, the first encapsulating layer 202 uses polyolefin elastomer (POE) as the matrix material, and adds 0.3% of a benzotriazole UV absorber as the first UV absorber. The second encapsulating layer 302 also uses polyolefin elastomer (POE) as the matrix material, but adds 0.9% of a compound UV absorber (containing benzotriazole and hydroxyphenyltriazine) and 0.3% of a hindered amine light stabilizer, which together form the second UV absorber system. Those skilled in the art will understand that there are many types of UV absorbers, including benzophenones, salicylates, etc., in addition to those mentioned above. Any UV absorber that can effectively absorb UV light in the polymer matrix and has good compatibility with the matrix material can be selected. The specific amount added can be optimized and adjusted based on the molar extinction coefficient of the selected UV absorber and the final target optical curve, within the above-mentioned proportional relationship.

[0047] As an optional implementation, to compensate for the slight loss of visible light that may result from completely blocking the ultraviolet band, white high-reflectivity fillers such as rutile titanium dioxide can be added to the second encapsulation layer 302. This reflects visible light and higher wavelengths that are not absorbed by the battery back for secondary absorption, thereby improving the overall efficiency of the module. However, this is not a necessary condition for achieving the second optical filtering characteristic. Furthermore, the high-reflectivity filler can undergo organic coating treatment to ensure its dispersion and compatibility in the matrix material. The addition amount is typically 5% to 15% of the mass of the matrix material.

[0048] In some embodiments, the thickness of the second encapsulating adhesive layer 302 can be 0.4mm to 0.6mm, for example, 0.5mm, and the thickness tolerance of the second encapsulating adhesive layer 302 and the first encapsulating adhesive layer 202 can be consistent to ensure the uniformity after lamination.

[0049] It should be noted that the asymmetrical configuration of the first encapsulation structure 200 and the second encapsulation structure 300 provides a synergistic solution to the problem of balancing high initial power and low UV degradation in double-glass photovoltaic modules. The selective transmission strategy of the first encapsulation structure 200 ensures maximum utilization of light energy in the main power generation direction, while the comprehensive blocking strategy of the second encapsulation structure 300 precisely addresses the main contradiction leading to the performance degradation of BC cells—backside UV invasion. The synergy between the two enables the double-glass photovoltaic module to achieve the optimal balance between reliability (low UV degradation) and economy (high initial power) as a whole, thus jointly resolving the inherent contradiction of existing symmetrical solutions.

[0050] To further optimize the performance of the aforementioned double-glass photovoltaic module and more accurately reflect the functional emphasis of the light-facing side 100a on light energy utilization and the back-facing side 100b on ultraviolet protection, this application also provides the following preferred optical performance relationship scheme.

[0051] As mentioned above, the first packaging structure 200 and the second packaging structure 300 have different optical filtering characteristics. In a preferred embodiment, the transmittance of the first packaging structure 200 to the UVA band is less than the transmittance of the first packaging structure 200 to the visible light and above bands; and / or, the transmittance of the first packaging structure 200 to the UVA band is less than the transmittance of the second packaging structure 300 to the visible light and above bands. This limitation aims to further clarify the spectral management priority within the first packaging structure 200 and between the first packaging structure 200 and the second packaging structure 300 from a relative perspective. Specifically, by making the transmittance of the UVA band of the light-facing surface 100a lower than that of the visible light and above bands, it is emphasized that even though the light-facing surface 100a allows some UVA band transmission, its primary task is still to ensure the transmission of higher-energy visible light and above bands. Making the transmittance of the UVA band of the light-facing surface 100a lower than that of the visible light and above bands of the back-facing surface 100b, at the system level, defines the "baseline" role of the second packaging structure 300 in allowing light transmission. Even if it focuses on protection, its ability to transmit visible light and above bands should not be lower than the ability of the light-facing surface 100a to transmit ultraviolet light. This is consistent with the logic of generating electricity from the back using scattered light.

[0052] This design makes the spectral selectivity of the first encapsulation structure 200 more pronounced, with its optical curve typically exhibiting a clear upward slope between the UVA and visible light bands. Its advantage lies in its ability to more clearly distinguish the boundary between "usable ultraviolet" and "primarily power-generating visible light," guiding formulation design to focus more on optimizing the performance of key wavelengths. Those skilled in the art will understand that achieving this relative magnitude does not depend on absolute transmittance values, but rather on adjusting the type and concentration of ultraviolet absorbers and any other functional additives (such as light-converting materials). For example, if a material that converts UVA to visible light is added to the front encapsulation film, although the UVA band is absorbed, the converted visible light contributes to the final "visible and above" transmittance, thus satisfying the same relative magnitude.

[0053] Furthermore, in another preferred embodiment, the blocking rate of the first packaging structure 200 for the UVC and UVB bands is less than the blocking rate of the second packaging structure 300 for the ultraviolet band; and / or, the transmittance of the first packaging structure 200 for visible light and above is greater than the transmittance of the second packaging structure 300 for visible light and above. This limitation directly quantifies the intensity of asymmetry through a comparison of performance parameters, explicitly requiring that the second packaging structure 300 be more thorough in blocking the ultraviolet band than the first packaging structure 200, while the first packaging structure 200 is more efficient in transmitting visible light than the second packaging structure 300. This is the most direct numerical manifestation of the "selective first, comprehensive second" principle.

[0054] By employing the aforementioned specific relative relationships of optical performance, the preferred embodiment of this application enables the optical management strategy of double-glass photovoltaic modules to possess quantifiable and comparable technical characteristics, facilitating quality control and technical effect evaluation during production. This further helps to solve the aforementioned problem of how to accurately balance the functions of the light-facing surface 100a and the backlight surface 100b, thereby synergistically enhancing the overall technical effect of the asymmetric spectral management of this application.

[0055] It is understood that the comparison of the above relative relationships is based on the same or comparable measurement standards and methods. The specific test wavelength ranges for blocking rate and transmittance can be defined according to industry standards or internal company specifications. As long as the above-mentioned magnitude relationship is met under the defined measurement conditions, it should be considered to fall within the scope of this application.

[0056] In order to provide a set of achievable and effective specific performance parameter ranges for the first and second optical filtering characteristics, and to ensure that the performance of the double-glass photovoltaic module reaches the optimal balance, the embodiments of this application also quantify the key optical parameters.

[0057] In one specific embodiment, the first encapsulation structure 200 has a blocking rate of 95% or more for the UVC and UVB bands; and / or, the first encapsulation structure 200 has a transmittance of 20% to 60% for the UVA band; and / or, the first encapsulation structure 200 has a transmittance of 93% or more for the visible light and above bands. Simultaneously, the second encapsulation structure 300 has a blocking rate of 99% or more for the ultraviolet band; and / or, the second encapsulation structure 300 has a transmittance of 85% or more for the visible light and above bands.

[0058] This series of numerical ranges provides clear performance benchmarks for the first and second optical filtering characteristics. For the first packaging structure 200, a UVC / UVB band blocking rate of ≥95% ensures that harmful short-wave ultraviolet rays are effectively suppressed; a UVA band transmittance of 20%~60% is a trade-off range, too low and usable ultraviolet energy is lost, too high and unnecessary ultraviolet aging risk may be increased; a high visible light transmittance of ≥93% is key to ensuring high initial power. For the second packaging structure 300, a total ultraviolet blocking rate of ≥99% constitutes strong ultraviolet protection for the battery back surface; while a visible light transmittance of ≥85% ensures that while providing top-level ultraviolet protection, the transmittance of the back surface 100b is not excessively sacrificed, taking into account the gain potential of the bi-directional power generation back surface 100b or at least maintaining the appearance transparency.

[0059] Specifically, these parameters can be achieved through refined material formulation design. For example, for the first encapsulating layer 202, a sharp UV absorber in the short-wave ultraviolet region is selected, and the addition amount is controlled at around 0.2%, which can achieve high blocking in the UVC / UVB bands. At the same time, through the spectral characteristics of the UV absorber itself or by combining it with a small amount of light conversion material, the transmittance in the UVA band is kept at around 40%, and the visible light transmittance is made to over 94% by selecting a highly transparent matrix resin and optimizing the processing technology. For the second encapsulating layer 302, a high-addition compound stabilizer system is used, such as adding more than 0.8% of a highly efficient UV absorber and a hindered amine light stabilizer, to ensure that the transmittance is less than 1% at any UV wavelength. And by optimizing the filler and reducing impurities, a high visible light transparency is maintained, reaching over 88%.

[0060] Those skilled in the art will understand that the endpoints of the above numerical ranges are merely examples and can be fine-tuned in actual production based on factors such as battery type, industry standards, and cost. For example, the transmittance of the first encapsulation structure 200 to the UVA band can preferably be 30%–50%, and the transmittance of the second encapsulation structure 300 to visible light can preferably be 87%–92%. These adjusted ranges should also be considered within the scope of this application. By adopting these quantitative indicators, the asymmetric encapsulation structure provided in this application is no longer a qualitative description but becomes a characteristic of an industrially manufactured and inspectable product.

[0061] Experiments show that the power degradation of the double-glass photovoltaic module using this solution can be stably controlled below 3.0% after UV60 testing, while its initial power loss is much lower than that of the traditional solution that uses full-blocking films on both sides.

[0062] The present invention also provides a method for preparing a double-glass photovoltaic module. Figure 3 A flowchart of a method for fabricating a double-glass photovoltaic module is provided as an embodiment of this application, such as... Figure 3 As shown, the fabrication method of a double-glass photovoltaic module includes: Step S100: Place the battery string layer 100 on the second packaging structure 300. The backlight surface 100b of the battery string layer 100 is attached to the surface of the second packaging structure 300. The second packaging structure 300 has a second optical filtering characteristic, which includes blocking and / or converting the ultraviolet band and transmitting visible light and above. Step S200: Place the first encapsulation structure 200 on the light-facing surface 100a of the battery string layer 100. The first encapsulation structure 200 has first optical filtering characteristics, which include: blocking and / or converting UVC and UVB bands, and transmitting UVA and visible light and above bands; and; Step S300: Laminate the first encapsulation structure 200, the battery string layer 100 and the second encapsulation structure 300 together.

[0063] Specifically, in combination Figure 1 and Figure 2 As shown, step S100 is first executed, in which the battery string layer 100 is placed on the second encapsulation structure 300, and the backlight surface 100b of the battery string layer 100 is bonded to the surface of the second encapsulation structure 300. The second encapsulation structure 300 has a second optical filtering characteristic, that is, it can block and / or convert the ultraviolet band, while allowing visible light and above to pass through. In specific operation, the second encapsulation structure 300 can be a pre-fabricated double-layer structure, for example, one layer is a second glass layer 301, and the other layer is a second encapsulating adhesive layer 302 that already possesses the second optical filtering characteristic. The battery string layer 100 is then placed on the second encapsulating adhesive layer 302.

[0064] In step S200, the first encapsulation structure 200 is placed on the light-facing surface 100a of the battery string layer 100. The first encapsulation structure 200 has first optical filtering characteristics, namely, blocking and / or converting UVC and UVB bands while allowing UVA and visible light and above to pass through. The first encapsulation structure 200 can also be a prefabricated double-layer structure, for example, one layer is a first glass layer 201, and the other layer is a first encapsulating adhesive layer 202 with the first optical filtering characteristics. The first encapsulating adhesive layer 202 is then placed over the battery string layer 100 to complete the entire module stack-up.

[0065] In step S300, the first encapsulation structure 200, the battery string layer 100, and the second encapsulation structure 300 are laminated together. The lamination process, through vacuuming, heating, and pressurizing, melts, flows, and cross-links the first encapsulation adhesive layer 202 and the second encapsulation adhesive layer 302, ultimately forming a robust, sealed, and bubble-free complete component. This step is crucial for integrating all the independent structures into a functional whole.

[0066] In order to optimize the lamination process to adapt to the lamination of the first encapsulating adhesive layer 202 and the second encapsulating adhesive layer 302 with special optical properties and to ensure encapsulation quality, especially when the different formulations of the first encapsulating adhesive layer 202 and the second encapsulating adhesive layer 302 may lead to differences in crosslinking rates, this application has specially designed the lamination process.

[0067] Specifically, during lamination, the first encapsulation structure 200, the battery string layer 100, and the second encapsulation structure 300 are laminated together through two laminations. The temperature range for the two laminations can be 120℃~150℃, and the temperature of the first lamination is controlled to be lower than that of the second lamination; for example, the temperature of the first lamination can be 125℃, and the temperature of the second lamination can be 150℃. Simultaneously, the vacuum degree of the first lamination is controlled to be -70kPa~-30kPa, and the vacuum degree of the second lamination can be -70kPa~-50kPa; for example, the first lamination can be divided into three stages, with vacuum degrees of -70kPa, -50kPa, and -30kPa respectively, and the second lamination can also be divided into three stages, with vacuum degrees of -60kPa, -40kPa, and -20kPa respectively. In addition, the first lamination time can be 123s~126s, and the second lamination time can be 458s~462s; for example, the first lamination time can be 125s, and the second lamination time can be 460s, while the conventional first lamination time is 120s and the second lamination time is 450s. By increasing the lamination time, it is ensured that the two layers of adhesive film achieve full cross-linking and interface fusion at the same time, avoiding incomplete fusion or bubbles, and improving the lamination effect.

[0068] The advantage of the two-step lamination method in this embodiment lies in the following: The first step, with a lower temperature and relatively loose vacuum, primarily aims to soften the first encapsulating layer 202 and the second encapsulating layer 302 initially, expel most of the interlayer air, and initiate a preliminary cross-linking reaction, achieving initial adhesion and shaping. This prevents the cell from shifting due to a rapid decrease in viscosity of the first and second encapsulating layers 202 caused by a sudden temperature rise. The second step, with a higher temperature and a more stable high vacuum, aims to completely melt the first and second encapsulating layers 202 and 302, completely expel residual air bubbles, and complete sufficient cross-linking and curing, forming a final, strong interfacial bond and stable material properties. This gradient heating process is particularly beneficial for the simultaneous and good curing of different encapsulant film formulations, preventing stress or incomplete fusion defects caused by mismatched crosslinking speeds. While ensuring a tight bond between the first encapsulation structure 200 and the second sealing structure without bubbles, it also protects the optical functional characteristics of the first encapsulation layer 202 and the second encapsulation layer 302, ultimately guaranteeing the finished product quality and long-term reliability of the module (the weld tensile test pass rate reaches over 98.5%). At the same time, after cooling, the first encapsulation layer 202 and the second encapsulation layer 302 can be completely peeled off from the module interface, with an average peeling force of 1.8 N / cm. After peeling, there is no visible adhesive residue on the surface of the cell, and the solder joints are fully exposed for easy inspection.

[0069] Those skilled in the art will understand that the specific temperature, vacuum level, and holding time during lamination can be optimized and adjusted based on the crosslinking kinetics curves of the first encapsulating adhesive layer 202 and the second encapsulating adhesive layer 302. For example, the temperature for the first lamination can be selected between 125°C and 135°C, and the temperature for the second lamination can be selected between 140°C and 150°C. The vacuum level is also set to ensure effective gas removal without causing glass deformation.

[0070] Next, taking a distributed photovoltaic power station located in a high ultraviolet radiation area (such as a plateau or desert) as an example, the power station uses a double-glass photovoltaic module (using BC cells) based on this embodiment. Throughout the entire life cycle of the double-glass photovoltaic module, the technical effect of this application is dynamically demonstrated.

[0071] In the initial stage of grid connection of double-glass photovoltaic modules, due to the high visible light transmittance (transmittance ≥93%) and partial UVA band transmittance (transmittance 20%~60%) of the first encapsulation structure 200, the light-facing surface 100a of the double-glass photovoltaic module can capture the effective energy in sunlight to the maximum extent. This makes its initial power output significantly higher than that of traditional double-glass photovoltaic modules (which use double-sided full UV cut-off film), giving full play to the high efficiency advantage of BC cells and resulting in higher power generation revenue.

[0072] During power plant operation, the double-glass photovoltaic module continuously withstands the harsh outdoor environment, especially intense ultraviolet radiation. Ultraviolet light incident from the back surface 100b of the double-glass photovoltaic module (including ground reflection and atmospheric scattering) is almost completely blocked by the second encapsulation structure 300, which has a high ultraviolet blocking rate (≥99%). This provides continuous and effective protection for the back passivation layer and dense electrodes of the BC cell, fundamentally suppressing ultraviolet degradation.

[0073] After the power station has been operating for a period of time (e.g., equivalent to the cumulative irradiance tested in the UV60 test of the IEC standard), the double-glass photovoltaic module was randomly inspected. Test data showed that the UV degradation of the double-glass photovoltaic module was stably controlled below 3.0%, indicating high reliability. In contrast, compared to traditional double-glass photovoltaic modules (using double-sided full UV conversion film or double-sided full UV cut-off film), this double-glass photovoltaic module exhibited even less UV degradation, or although the degradation met the standard, the initial power output was already compromised.

[0074] In this application scenario, the double-glass photovoltaic module provided in this application significantly increases the total power generation of the photovoltaic power plant throughout its entire life cycle.

[0075] In this document, the terms "transmittance" and "blocking rate" are relative values, referring to the ratio of transmitted light energy to incident light energy, and the ratio of blocked (including absorbed and converted) light energy to incident light energy, respectively, which can be measured by a spectrophotometer. In this application, "light-facing side 100a" generally refers to the side of the module that is expected to receive the main solar radiation under normal installation and use conditions, and is usually also referred to as the front or front side. "Shadow-facing side 100b" is the side opposite to "light-facing side 100a", and is usually also referred to as the back or back side.

[0076] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0077] It should also be noted that although preferred embodiments have been disclosed above, these embodiments are not intended to limit this application. Any person skilled in the art can make many possible variations and modifications to the technical solutions of this application, or modify them into equivalent embodiments, without departing from the scope of the technical solutions of this application. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this application, without departing from the content of the technical solutions of this application, shall still fall within the scope of protection of the technical solutions of this application.

[0078] It should also be understood that, unless otherwise specified or indicated, the terms “first,” “second,” “third,” etc., in the specification are used only to distinguish the various components, elements, and steps in the specification, and not to indicate the logical or sequential relationships between the various components, elements, and steps.

[0079] Furthermore, it should be recognized that the terminology described herein is used only to describe particular embodiments and is not intended to limit the scope of this application. It must be noted that the singular forms “a” and “an” as used herein include plural bases unless the context clearly indicates the opposite. For example, a reference to “a step” or “an apparatus” means a reference to one or more steps or apparatuses, and may include secondary steps and secondary apparatuses. All conjunctions used should be understood in the broadest sense. Also, the word “or” should be understood as having the definition of logical “or”, not logical “exclusive OR”, unless the context clearly indicates the opposite. Furthermore, implementations of the methods and / or devices in the embodiments of this application may include performing selected tasks manually, automatically, or in combination.

Claims

1. A double-glass photovoltaic module, characterized in that, include: Battery stacking; A first packaging structure is located on the light-facing side of the battery string layer. The first packaging structure has a first optical filtering characteristic, which includes blocking and / or converting the UVC and UVB bands, and transmitting the UVA band and visible light and above. The second packaging structure is located on the back surface of the battery string layer. The second packaging structure has a second optical filtering characteristic, which includes blocking and / or converting the ultraviolet band and transmitting visible light and above.

2. The double-glass photovoltaic module according to claim 1, characterized in that, The transmittance of the first packaging structure to the UVA band is less than the transmittance of the first packaging structure to the visible light and above bands. And / or, the transmittance of the first packaging structure to the UVA band is less than the transmittance of the second packaging structure to the visible light and above bands.

3. The double-glass photovoltaic module according to claim 1, characterized in that, The first packaging structure has a lower blocking rate for the UVC and UVB bands than the second packaging structure has for the ultraviolet band. And / or, the transmittance of the first packaging structure to the visible light and above wavelengths is greater than the transmittance of the second packaging structure to the visible light and above wavelengths.

4. The double-glass photovoltaic module according to any one of claims 1 to 3, characterized in that, The first packaging structure has a blocking rate of 95% or greater for the UVC and UVB bands; And / or, the transmittance of the first encapsulation structure to the UVA band is 20%~60%; And / or, the first packaging structure has a transmittance of 93% or more for visible light and above wavelengths; And / or, the second packaging structure has a blocking rate of 99% or greater for the ultraviolet band; And / or, the second packaging structure has a transmittance of 85% or more for visible light and above.

5. The double-glass photovoltaic module according to claim 1, characterized in that, Both the first packaging structure and the second packaging structure have at least two stacked packaging layers. Each of the packaging layers of the first packaging structure has the first optical filtering characteristic, and each of the packaging layers of the second packaging structure has the second optical filtering characteristic.

6. The double-glass photovoltaic module according to claim 5, characterized in that, The first encapsulation structure and / or the second encapsulation structure each have two stacked encapsulation layers, namely a glass layer and an encapsulating adhesive layer, wherein the encapsulating adhesive layer is closer to the battery string layer than the glass layer. Alternatively, the at least two stacked encapsulation layers of the first encapsulation structure and / or the second encapsulation structure are all three layers, namely a glass layer, an optical filter layer and an encapsulating adhesive layer, wherein the encapsulating adhesive layer is closer to the battery string layer than the glass layer, and the optical filter layer is located between the glass layer and the encapsulating adhesive layer.

7. The double-glass photovoltaic module according to claim 5 or 6, characterized in that, A first ultraviolet absorber is added to any of the encapsulation layers of the first encapsulation structure, and a second ultraviolet absorber is added to any of the encapsulation layers of the second encapsulation structure. The amount of the second ultraviolet absorber added is greater than the amount of the first ultraviolet absorber added, and / or the mass of the first ultraviolet absorber added is 0.1% to 0.5% of the mass of the matrix material of the corresponding encapsulation layer.

8. The double-glass photovoltaic module according to claim 1, characterized in that, The battery string layer is a back-contact battery string layer.

9. A method for preparing a double-glass photovoltaic module, characterized in that, include: A battery string layer is placed on a second packaging structure, the back surface of the battery string layer is attached to the surface of the second packaging structure, and the second packaging structure has a second optical filtering characteristic, which includes: blocking and / or converting the ultraviolet band and transmitting visible light and above. The first encapsulation structure is placed on the light-facing side of the battery string layer. The first encapsulation structure has a first optical filtering characteristic, which includes: blocking and / or converting the UVC and UVB bands, and transmitting the UVA band and visible light and above; and; The first packaging structure, the battery string layer, and the second packaging structure are laminated together.

10. The method for preparing a double-glass photovoltaic module according to claim 9, characterized in that, Both the first encapsulation structure and the second encapsulation structure include a glass layer and an encapsulating adhesive layer. The encapsulating adhesive layer is closer to the battery string layer than the glass layer. The encapsulating adhesive layer has the first optical filtering characteristic or the second optical filtering characteristic. as well as, The first encapsulation structure, the battery string layer, and the second encapsulation structure are laminated together in two stages. The lamination temperature is 120℃~150℃, and the temperature of the first lamination is lower than that of the second lamination. The vacuum degree of the first lamination is -70kPa~-30kPa, and the time is 123s~126s. The vacuum degree of the second lamination is -70kPa~-50kPa, and the time is 458s~462s.

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