Conductive adhesive film, back sheet, back contact solar cell module

Abstract

The application provides a conductive adhesive film, a back plate and a back contact solar cell module, and relates to the technical field of solar photovoltaic technology. The conductive adhesive film comprises an adhesive film and a plurality of solder strips embedded on one side of the adhesive film; one side of the solder strips is arranged on the adhesive film, and polymer protrusions are arranged between adjacent solder strips. In the process of electrically connecting the positive and negative electrodes of the cells by using the conductive adhesive film, the solder strips are opposite to the electrodes of the cells, the polymer protrusions are arranged in the area between the electrodes of the cells, the polymer protrusions squeeze out the air in the area between the electrodes of the cells, and the reliability of the module is improved. During the laminating process, the polymer protrusions and the adhesive film soften and flow, cross-linking reaction occurs, the polymer protrusions and the adhesive film are cross-linked to form an integrated structure, the adhesive property is good, and the reliability of the module is improved.

Description

Technical Field

[0001] This invention relates to the field of solar photovoltaic technology, and in particular to a conductive adhesive film, a backsheet, and a back contact solar cell module. Background Technology

[0002] Back-contact solar cell modules have no main grid lines on the front side, with both the positive and negative electrodes located on the back of the cell. This reduces shading, effectively increases the short-circuit circuit of the cell, improves the energy conversion efficiency of the module, and makes it more aesthetically pleasing, thus leading to its wide range of applications.

[0003] Currently, in the conductive interconnection process of back-contact solar cell modules, conductive backsheets are mainly used to connect the positive and negative terminals of the cells, or solder ribbons are used to connect the positive and negative terminals of the cells. Solder ribbon connections are widely used due to their lower cost.

[0004] In the process of forming a back-contact solar cell module by connecting the solder strips, air bubbles are prone to appear in the module, which can reduce the reliability of the module. Summary of the Invention

[0005] This invention provides a conductive adhesive film, a backsheet, and a back-contact solar cell module, aiming to solve the problem of poor reliability of back-contact solar cell modules.

[0006] According to a first aspect of the present invention, a conductive adhesive film is provided for use in a back-contact solar cell assembly. The conductive adhesive film includes: an adhesive film and a plurality of solder strips embedded on one side of the adhesive film; on one side of the adhesive film where the solder strips are disposed, polymer protrusions are disposed between adjacent solder strips.

[0007] In the process of conductively interconnecting the positive and negative electrodes of the battery using the aforementioned conductive adhesive film, the solder ribbon is aligned with the electrodes of the battery cell, and the aforementioned polymer protrusions precisely fill the area between the electrodes of the battery cell. Thus, the polymer protrusions effectively squeeze out the air in the area between the electrodes of the battery cell. This is equivalent to the polymer protrusions having essentially squeezed out the air in the area between the electrodes of the battery cell before lamination, resulting in virtually no air bubbles in the back-contact solar module obtained through lamination, thereby improving the reliability of the module.

[0008] Optionally, the height of the polymer protrusion is less than or equal to the height of the solder strip protruding from the adhesive film.

[0009] Optionally, the polymer protrusions may be strip-shaped or dot-shaped.

[0010] When the polymer protrusion is strip-shaped, the width of the polymer protrusion is 3-10 mm;

[0011] When the polymer protrusions are dot-shaped protrusions, the diameter of the polymer protrusions is 1-5 mm.

[0012] Optionally, the polymer protrusions are either continuously extending strip-shaped protrusions or discontinuously extending strip-shaped protrusions.

[0013] Optionally, when the polymer protrusions are dot-shaped protrusions, the spacing between adjacent polymer protrusions is 2-6 mm in the direction parallel to the extension of the solder strip.

[0014] Optionally, the polymer protrusion is integrally formed with the adhesive film, or the polymer protrusion is bonded or hot-pressed onto the adhesive film.

[0015] Optionally, the polymer protrusions are selected from scraps of the adhesive film, which are bonded or heat-pressed onto the adhesive film.

[0016] Optionally, a release layer is provided on the side of the adhesive film away from the solder strip; the thickness of the release layer is 50-300 μm.

[0017] Optionally, the polymer protrusions are selected from at least one of: ethylene-vinyl acetate copolymer, ethylene-octene copolymer, polyvinyl butyral, and silicone.

[0018] According to a second aspect of the present invention, a backsheet is provided for use in a back-contact solar cell assembly, the backsheet comprising: a backsheet substrate and a plurality of protrusion units spaced apart on the light-facing surface of the backsheet substrate; the protrusion unit being composed of a single protrusion or a plurality of protrusions arranged at intervals.

[0019] In the aforementioned backsheet, the backsheet substrate is pressed against the light-facing protrusions and then encapsulated with an encapsulating film. This encapsulating film at the protrusions is deformed and pressed into the gaps between adjacent solder strips. The encapsulating film at the protrusions precisely fills the area between the electrodes of the solar cells. The encapsulating film at the protrusions effectively squeezes out the air in the area between the electrodes of the solar cells. This means that before lamination, the encapsulating film at the protrusions has essentially squeezed out the air in the area between the electrodes of the solar cells, resulting in virtually no air bubbles in the back-contact solar module obtained through lamination, thus improving the reliability of the module.

[0020] Optionally, the height of the protrusion is 20-200 μm.

[0021] Optionally, the protrusion may be a strip-shaped protrusion or a dot-shaped protrusion;

[0022] When the protrusion is a strip-shaped protrusion, the width of the protrusion is 3-10 mm;

[0023] When the protrusion is a dotted protrusion, the diameter of the protrusion is 1-5 mm.

[0024] Optionally, when the protrusion is a dotted protrusion, the spacing between adjacent protrusions within the same protrusion unit is 2-6 mm.

[0025] Optionally, the material of the backplate substrate is glass.

[0026] Optionally, the protrusion is integrally formed with the back plate substrate;

[0027] Alternatively, if the backing substrate is a glass backing substrate, the raised printing is sintered onto the glass backing substrate.

[0028] According to a third aspect of the present invention, a back-contact solar cell assembly is provided, comprising: a cover plate, a front encapsulation material, a solar cell, a rear encapsulation film, and a back sheet arranged in sequence.

[0029] The backing film has several solder strips embedded on its light-facing surface; the backing plate includes a backing plate substrate and several protrusions spaced apart on the light-facing surface of the backing plate substrate; the protrusions and the solder strips are distributed alternately.

[0030] In the aforementioned back-contact solar cell module, the encapsulating film is pressed against the protrusions on the light-facing side of the backsheet. The encapsulating film at the protrusions is deformed and pressed into the gaps between adjacent solder strips. The encapsulating film at the protrusions fills the area between the electrodes of the solar cell. The encapsulating film at the protrusions effectively squeezes out the air in the area between the electrodes of the solar cell before lamination. This is equivalent to the encapsulating film at the protrusions having essentially squeezed out the air in the area between the electrodes of the solar cell before lamination. As a result, the back-contact solar cell module obtained by lamination is basically free of air bubbles, thus improving the reliability of the module.

[0031] Optionally, polymer protrusions are provided between adjacent solder strips on the light-facing surface of the post-encapsulation film. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A schematic diagram of the structure of a conductive adhesive film according to an embodiment of the present invention is shown;

[0034] Figure 2 A schematic diagram of the conductive interconnection between a conductive adhesive film and a battery cell in an embodiment of the present invention is shown.

[0035] Figure 3A schematic diagram of a back-contact solar cell module according to an embodiment of the present invention is shown;

[0036] Figure 4 A cross-sectional schematic diagram of a conductive adhesive film according to an embodiment of the present invention is shown;

[0037] Figure 5 A schematic diagram of the structure of another conductive adhesive film in an embodiment of the present invention is shown;

[0038] Figure 6 A schematic diagram of another backplate structure in an embodiment of the present invention is shown;

[0039] Figure 7 A schematic diagram of the stacked structure of the layers before lamination is shown;

[0040] Figure 8 A schematic diagram of another back-contact solar cell assembly in an embodiment of the present invention is shown.

[0041] Explanation of the attached drawing numbers:

[0042] 1, 2-Solder ribbon, 11-Encapsulation film or post-encapsulation film, 12-Polymer protrusion, 13-Release layer, 3-Battery cell, 4-Cover plate, 5-Front encapsulation material, 7-Backsheet, 71-Backsheet substrate, 72-Protrusion. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] The inventors of this invention discovered through research that the presence of air bubbles in solar modules can easily reduce module reliability because: Solder ribbons are embedded in the adhesive film, and during lamination, the positive and negative electrodes of the solar cells are aligned with the solder ribbons to achieve precise alignment between the solder ribbons and the cell electrodes. Since back-contact solar cell modules typically have a large number of electrodes, a large number of solder ribbons are required. The solder ribbons embedded in the adhesive film can easily lift the entire adhesive film, resulting in air pockets between adjacent solder ribbons—that is, air pockets exist in the areas between the cell electrodes. During lamination, these air pockets are difficult to completely remove, forming air bubbles within the module. These air bubbles weaken the adhesion between the adhesive film and the solar cells, thereby reducing module reliability.

[0045] Reference Figure 1 , Figure 1A schematic diagram of a conductive adhesive film according to an embodiment of the present invention is shown. This conductive adhesive film is used in a back-contact solar cell module. The conductive adhesive film includes: an adhesive film 11 and a plurality of solder strips embedded on one side of the adhesive film 11. The number of solder strips included in the conductive adhesive film is not specifically limited. Solder strip 1 and solder strip 2 are two adjacent solder strips. On one side of the adhesive film 11 where solder strip 2 is disposed, polymer protrusions 12 are disposed between adjacent solder strips. Figure 1 In this assembly, a polymer protrusion 12 is provided between two adjacent solder strips 1 and 2. In the back-contact solar cell module, this encapsulating film 11 is a post-encapsulation film. The side of the encapsulating film 11 where the solder strips 1 are located can be the light-facing side of the encapsulating film 11.

[0046] References in this application Figure 2 As shown, Figure 2 This diagram illustrates a conductive interconnection between a conductive adhesive film and a solar cell according to an embodiment of the present invention. During the conductive interconnection of the positive and negative electrodes of the solar cell using this conductive adhesive film, solder ribbon 1 or solder ribbon 2 is directly opposite the electrodes of the solar cell 3. The polymer protrusions 12 precisely fill the area between the electrodes of the solar cell 3, thereby effectively squeezing out the air in the area between the electrodes of the solar cell 3. Essentially, before lamination, the polymer protrusions 12 have already substantially squeezed out the air in the area between the electrodes of the solar cell 3, resulting in a back-contact solar module with virtually no air bubbles, thus improving the reliability of the module.

[0047] At the same time, refer to Figure 3 As shown, Figure 3 A schematic diagram of a back-contact solar cell module according to an embodiment of the present invention is shown. In this application, during the lamination process, the polymer protrusions and the adhesive film soften and flow, undergoing a cross-linking reaction. The polymer protrusions and the adhesive film cross-link to form a defect-free integral structure, resulting in almost no cracks between the polymer protrusions and the adhesive film, good adhesion performance, and improved module reliability. Figure 3 In the diagram, 4 is the cover plate, 5 is the front sealing material, and 7 is the back plate.

[0048] For example, the most commonly used EVA and POE films and polymer protrusions soften and flow during the lamination process. Crosslinking agents such as tert-butyl percarbonate-2-ethylhexyl peroxide (TBEC) or dicumyl peroxide (DCP) decompose upon heating to generate free radicals, which trigger crosslinking reactions between polymer molecules, fusing and crosslinking into an integrated network structure. This results in very few or no cracks or bubbles, good adhesion, and improved component reliability.

[0049] Optional, refer to Figure 1As shown, the height h2 of the polymer protrusion 12 is less than or equal to the height h1 of the solder ribbon 1 protruding from the adhesive film 11. On one hand, the polymer protrusion does not affect the accurate alignment of the solder ribbon with the electrodes of the solar cell, and its size matches the area between the electrodes of the solar cell, allowing air to be squeezed out from the area between the electrodes of the solar cell 3. On the other hand, during the lamination process, the polymer protrusion reacts with the adhesive film to fill the gaps between the solar cells. For example, the height of the polymer protrusion can be between 20-200 μm.

[0050] Optionally, the polymer protrusions can be strip-shaped or dot-shaped. The polymer protrusions offer a variety of shapes and options.

[0051] Optionally, the polymer protrusions can be continuous or discontinuous strip-shaped protrusions, with the length corresponding to the length of the electrodes in the solar cell. This effectively compresses and removes air from the area between the electrodes of the solar cell 3. Furthermore, the polymer protrusions offer a variety of shape options. For discontinuous strip-shaped protrusions, not only is the air in the area between the electrodes of the solar cell 3 effectively compressed and removed, but material usage is also reduced.

[0052] Optionally, the aforementioned dot-shaped protrusions may include one of the following: a spherical structure, a cylindrical structure, a multifaceted cylindrical structure, a frustum or a pyramidal structure.

[0053] Optionally, when the polymer protrusion is a strip-shaped protrusion, its width is 3-10 mm; or, the width of the polymer protrusion can be 15% to 80% of the main grid spacing width of the solar cells in the back-contact battery assembly. This width range of polymer protrusions adapts to the area size between the electrodes of the solar cell, enabling the expulsion of air from the area between the electrodes. Simultaneously, this width allows the polymer protrusions to fill the gaps between the solar cells after cross-linking with the adhesive film during lamination.

[0054] Optionally, when the polymer protrusions are dot-shaped protrusions, their diameter is 1-5 mm. This diameter range is adapted to the size of the area between the electrodes of the solar cell, allowing air to be squeezed out from the area between the electrodes. Simultaneously, within this diameter range, during lamination, the polymer protrusions undergo a cross-linking reaction with the adhesive film, effectively filling the gaps between the solar cells.

[0055] Optional, refer to Figure 1 As shown, if Figure 1The polymer protrusions are dot-shaped protrusions. In the direction parallel to the extension of the solder strip 1, the spacing d1 between adjacent polymer protrusions is 2-6 mm, which can adapt to the spacing between the solder strips. At the same time, within this spacing range, after the polymer protrusions undergo a cross-linking reaction with the adhesive film during the lamination process, they can fill the gaps between the battery cells.

[0056] Optionally, the polymer protrusions are integrally formed with the adhesive film, or the polymer protrusions are bonded or hot-pressed onto the adhesive film.

[0057] Specifically, the polymer protrusions are integrally molded with the adhesive film. During the adhesive film manufacturing process, an extrusion device with protrusions is designed. Precursor particles (such as EVA particles) are stirred, mixed, heated, melted, extruded, cast, cooled, and conveyed to form an adhesive film with polymer protrusions. (See reference...) Figure 4 As shown, Figure 4 A cross-sectional schematic diagram of a conductive adhesive film according to an embodiment of the present invention is shown.

[0058] Alternatively, an adhesive can be used to bond the polymer protrusions to the adhesive film. The adhesive can be applied to the polymer protrusions or the adhesive film. The aforementioned adhesives are synthetic polymer adhesives, including polyvinyl acetate, polyvinyl acetal, acrylate, polystyrene, epoxy resin, acrylic resin, polyurethane resin, unsaturated polyester, butyl rubber, nitrile rubber, phenolic-polyvinyl acetal, or epoxy-polyamide. These adhesives are liquid adhesives or adhesive films at room temperature. A release layer is provided on one or both sides of the adhesive film for ease of handling.

[0059] Optionally, the adhesive can be fluorine-modified acrylic acid, epoxy-modified acrylic acid, or nanomaterial-modified acrylic acid. Modification of acrylic resin using ultraviolet light introduces the CF bond, one of the strongest known chemical bonds, with a bond energy as high as 460 kJ / mol. Fluoropolymers exhibit stronger chemical bonding and structural stability than any other polymer, possessing excellent weather resistance, UV resistance, and superior dielectric and insulating properties. Nanoparticles, with their small size and interfacial effects, enhance UV absorption, thereby improving the adhesive's UV resistance and weather resistance.

[0060] Alternatively, the polymer protrusions can be hot-pressed onto the adhesive film at a temperature of 50-150℃, a pressure of 0.1-0.5MPa, and a time of 1-60s, so that the polymer protrusions are evenly adhered to the adhesive film. Optionally, the hot-pressing temperature can be 80℃, the pressure 0.1MPa, and the hot-pressing time 5s.

[0061] Optionally, the polymer protrusions are selected from the scraps of the adhesive film. This eliminates the need for specialized manufacturing of polymer protrusions, allowing for flexible use of waste materials for secondary processing, effectively improving the utilization rate of the adhesive film material. This not only saves on processing time but also significantly reduces costs. For example, the polymer protrusions can be small strips of EVA or POE adhesive film with a thickness ratio between 1:5 and 1:1. After secondary cutting of thinner EVA or POE adhesive film scraps, they are hot-pressed or bonded to the adhesive film to form an adhesive film with polymer protrusions. EVA strips can be bonded to EVA or POE adhesive films, or vice versa. The EVA adhesive film thickness can be 150μm, and the EVA adhesive film strip size can be 5000μm × 5000μm × 100μm, with adjacent EVA adhesive film strips spaced 6mm apart in the direction parallel to the extension of the solder strip.

[0062] Optional, refer to Figure 5 As shown, Figure 5 A schematic diagram of the structure of another conductive adhesive film in an embodiment of the present invention is shown. In the above... Figure 1 Based on this, a release layer 13 is provided on the side of the adhesive film 11 away from the solder strip 1. The release layer 13 enables the conductive adhesive film to have a certain strength and good dimensional stability. Specifically, after heating at 150°C for 30 minutes, the longitudinal / transverse shrinkage rate of the release layer is ≤1.5% / 0.5%, or ≤0.8% / 0.2%, or ≤0.6% / 0.1%. The release layer can limit the dimensional shrinkage of the adhesive film during the preheating process to ensure the alignment of the solder strip in the adhesive film with the battery cell, improve processing accuracy and production yield, and effectively prevent solder strip misalignment during solder strip fixing and preheating. At the same time, the release layer can effectively suppress the bending of the battery cell. The release layer can limit the dimensional shrinkage of the adhesive film during processing and improve processing accuracy. The thickness of the release layer can be 50-300 μm, for example, the basis weight of the release layer is 30-45 g / m³. 2 This not only enhances strength and dimensional stability, but also reduces costs.

[0063] The adhesive film is formed on the release layer through a coating process. Optionally, the release layer is silicone paper with a basis weight between 30 g / m². 2 Up to 200g / m 2 Between. This release layer can adhere to the pre-impregnated adhesive resin layer (i.e., the adhesive layer), but it is also easy to separate the two; it does not chemically react with the adhesive layer or contaminate the adhesive.

[0064] Alternatively, a one-piece molded adhesive film with polymer protrusions can be hot-pressed onto a release layer. The hot-pressing temperature is between 50-150℃, the pressure is between 0.1-0.5MPa, and the hot-pressing time is 1-10 minutes, for example, a hot-pressing temperature of 80℃, a pressure of 0.1MPa, and a hot-pressing time of 1 minute. Alternatively, the adhesive film can be directly cast onto the release layer using an adhesive film extrusion device with protrusions, resulting in a better bonding effect.

[0065] Optionally, the polymer protrusions are selected from at least one of the following: ethylene-vinyl acetate copolymer (EVA), ethylene-octene copolymer (POE), polyvinyl butyral (PVB), and silicone. The polymer protrusions of the above materials can undergo a cross-linking reaction with the adhesive film during the lamination process to generate a defect-free integral structure with good adhesion performance, thereby improving the reliability of the component.

[0066] Optionally, the film may also be selected from at least one of ethylene-vinyl acetate copolymer (EVA), ethylene-octene copolymer (POE), polyvinyl butyral (PVB), and silicone, and the thickness of the film may be 100-800um.

[0067] In this application, the conductive adhesive film includes an adhesive film and a plurality of solder ribbons embedded in the adhesive film. Polymer protrusions are disposed between adjacent solder ribbons on the adhesive film. On the one hand, during the process of conductively interconnecting the positive and negative electrodes of the battery using this conductive adhesive film, the solder ribbons are directly opposite the electrodes of the battery cell, and the aforementioned polymer protrusions precisely fill the area between the electrodes of the battery cell, effectively squeezing out air from the area between the electrodes. On the other hand, during the lamination process, the polymer protrusions and the adhesive film soften and flow, undergoing a cross-linking reaction. The aforementioned polymer protrusions and the adhesive film cross-link to form an integral structure, resulting in almost no cracks between the polymer protrusions and the adhesive film, good adhesion performance, and improved module reliability.

[0068] This application also provides a backsheet for use in a back-contact solar cell module. (See reference...) Figure 6 As shown, Figure 6 A schematic diagram of another backsheet structure according to an embodiment of the present invention is shown. The backsheet 7 includes: a backsheet substrate 71 and a plurality of protruding units spaced apart on the light-facing surface of the backsheet substrate. Each protruding unit is composed of a protrusion 72 or a plurality of protrusions 72 arranged at intervals. The light-facing surface of the backsheet substrate 71 is the surface close to the solar cell, and the number of protrusions is not specifically limited.

[0069] Reference Figure 7 As shown, Figure 7 A schematic diagram of the stacked structure of the layers before lamination is shown. Figure 7In the diagram, 4 is the cover plate, 5 is the front encapsulation material, 3 is the solar cell, 1 is the solder ribbon, 11 is the rear encapsulation film, and 71 is the backsheet substrate. The solder ribbon 1 is embedded in the light-facing surface of the rear encapsulation film 11. The protrusions 72 on the light-facing surface of the backsheet substrate 71 press the rear encapsulation film 11, deforming and pressing the rear encapsulation film at the protrusions 72 into the gaps between adjacent solder ribbons 1. That is, the rear encapsulation film at the protrusions 72 fills the area between the electrodes of the solar cell 3. The rear encapsulation film at the protrusions 72 essentially squeezes out the air in the area between the electrodes of the solar cell 3. This is equivalent to the rear encapsulation film at the protrusions 72 having essentially squeezed out the air in the area between the electrodes of the solar cell 3 before lamination, resulting in virtually no air bubbles in the back-contact solar module obtained by lamination, thus improving the reliability of the module.

[0070] At the same time, refer to Figure 8 As shown, Figure 8 A schematic diagram of another back-contact solar cell module according to an embodiment of the present invention is shown. In this application, during the lamination process, the post-encapsulation film at the protrusion 72 and the post-encapsulation film at other locations soften and flow, undergoing a cross-linking reaction. The post-encapsulation film at the protrusion 72 and the post-encapsulation film at other locations cross-link to form a defect-free integral structure, resulting in almost no cracks between the post-encapsulation film at the protrusion 72 and the post-encapsulation film at other locations, good adhesion performance, and improved module reliability.

[0071] Optionally, the protrusion can be a strip or a dot, offering a variety of protrusion shapes to choose from.

[0072] Optionally, when the protrusion is a dot-shaped protrusion, the dot-shaped protrusion may include one of the following: a spherical structure, a cylindrical structure, a multi-faceted cylindrical structure, a frustum or a pyramidal structure, and the shape of the protrusion can be varied.

[0073] Optional, refer to Figure 6 As shown, the height h3 of the protrusion is 20-200um. On the one hand, after the protrusion is extruded and encapsulated, it will not affect the accurate alignment of the solder ribbon and the electrode of the solar cell, and it is compatible with the size of the area between the electrodes of the solar cell, which can squeeze out the air in the area between the electrodes of the solar cell. On the other hand, during the lamination process, the encapsulation film at the protrusion reacts with the encapsulation film at other locations through a cross-linking reaction, which can fill the gaps between the solar cells.

[0074] Optional, refer to Figure 6 As shown, when the protrusions are dot-shaped, the spacing d2 between adjacent protrusions within the same protrusion unit is 2-6 mm, which can accommodate the spacing between solder strips. Simultaneously, within this spacing range, during lamination, the post-encapsulation film at the protrusions undergoes a cross-linking reaction with the post-encapsulation film at other locations, effectively filling the gaps between the battery cells.

[0075] Optionally, when the protrusion is a strip-shaped protrusion, its width is 3-10 mm. Alternatively, the width of the protrusion can be 15% to 80% of the main grid spacing width of the cell in the back-contact battery assembly. This width range of protrusion is adapted to the area size between the electrodes of the cell, and can squeeze out the air in the area between the electrodes of the cell. At the same time, this width dimension, during the lamination process, allows the post-encapsulation film at the protrusion to cross-link with the post-encapsulation film at other locations, thus filling the gaps between the cells.

[0076] Optionally, when the protrusion is a dotted protrusion, its diameter is 1-5 mm. This diameter range is adapted to the area size between the electrodes of the solar cell, allowing air to be squeezed out from the area between the electrodes. Simultaneously, within this diameter range, during lamination, the post-encapsulation film at the protrusion reacts with the post-encapsulation film at other locations, effectively filling the gaps between the solar cells.

[0077] Optionally, the backsheet substrate can be made of glass, or it can also be made of: TPT solar backsheet substrate, TPE solar backsheet substrate, BBF solar backsheet substrate, APE solar backsheet substrate, EVA solar backsheet substrate, etc. The material of the protrusions can be the same as or different from the material of the backsheet substrate; for example, the protrusions can be made of glass. The hardness or rigidity of the protrusions in the above materials is much greater than the hardness or rigidity of the post-encapsulation film, thus allowing the post-encapsulation film at the contact point with the protrusions to be squeezed into the gap between adjacent solder strips.

[0078] For example, the backsheet substrate can be TPT, TPE, KPE, KPK, KPC, or KPF. The backsheet substrate can also be a polymer multilayer structure composed of an insulating layer, an adhesive layer, and / or a fluoropolymer coating made of insulating material (PET or PP).

[0079] Optionally, the protrusions are integrally formed with the backing substrate. Alternatively, if the backing substrate is a glass backing substrate, the protrusions are printed and sintered onto the glass backing substrate. Specifically, a mold with protrusions can be used to integrally form a backing substrate with several protrusions spaced apart on the light-facing side. Alternatively, if the backing substrate is a glass backing substrate, UV ink or sintered glass enamel ink can be used to screen print spaced protrusions on the light-facing side of the backing substrate, and the ink can be cured by UV light irradiation or sintered in a heating furnace at a temperature of about 600°C for 1 to 5 minutes to form the spaced protrusions.

[0080] In this embodiment of the invention, the light-facing surface of the backsheet substrate has several protrusions spaced apart. These protrusions on the light-facing surface of the backsheet substrate compress the encapsulating film, deforming and pressing the encapsulating film at the protrusions into the gaps between adjacent solder strips. The encapsulating film at the protrusions precisely fills the area between the electrodes of the solar cell, effectively squeezing out air from this area. This means that before lamination, the encapsulating film at the protrusions has essentially eliminated air from the area between the electrodes of the solar cell, resulting in a virtually bubble-free back-contact solar module and improved module reliability. Simultaneously, during lamination, the encapsulating film at the protrusions and the encapsulating film at other locations soften and flow, undergoing a cross-linking reaction. This cross-linking forms a defect-free integral structure, resulting in almost no cracks between the encapsulating film at the protrusions and the encapsulating film at other locations, providing excellent adhesion and further improving module reliability.

[0081] This invention also provides a back-contact solar cell module. (See attached image.) Figure 8 As shown, the assembly includes: a cover plate 4, a front encapsulation material 5, a battery cell 3, a rear encapsulation film 11, and a backplate 7, stacked sequentially. The backplate 11 has several solder ribbons 1 or 2 embedded in its light-facing surface. The backplate 7 includes a backplate substrate 71 and several protrusions 72 spaced apart on the light-facing surface of the backplate substrate 71. These protrusions 72 and solder ribbons 1 or 2 are distributed alternately at intervals.

[0082] The backsheet protrusions on the light-facing side are pressed into the encapsulating film, which deforms and presses the encapsulating film into the gaps between adjacent solder strips. The encapsulating film on the protrusions fills the area between the electrodes of the solar cell, effectively squeezing out the air in the area between the electrodes. This means that before lamination, the encapsulating film on the protrusions has essentially squeezed out the air in the area between the electrodes of the solar cell, resulting in virtually no air bubbles in the back-contact solar module obtained by lamination, thus improving the reliability of the module.

[0083] Meanwhile, during the lamination process, the post-encapsulation film at the protrusion 72 and the post-encapsulation film at other locations soften and flow, undergoing a cross-linking reaction. The post-encapsulation film at the protrusion 72 and the post-encapsulation film at other locations cross-link to form a defect-free integral structure, resulting in no cracks between the post-encapsulation film at the protrusion 72 and the post-encapsulation film at other locations, good adhesion performance, and improved component reliability.

[0084] Optionally, on the light-facing surface of the aforementioned post-encapsulation film, polymer protrusions are provided between adjacent solder ribbons. The light-facing surface of this post-encapsulation film is the surface near the solar cell in the back-contact solar cell assembly. Referring here to the aforementioned embodiment where a plurality of solder ribbons are embedded on one side of the film, and polymer protrusions are provided between adjacent solder ribbons on the side of the film where the solder ribbons are located, this method achieves the corresponding beneficial effects. To avoid repetition, it will not be repeated here.

[0085] The above-mentioned method for producing back-contact solar cell modules may include the following steps:

[0086] Step 101: Lay out the solar cell with the side containing the electrodes facing upwards; the solar cell is a back-contact solar cell.

[0087] A conductive material is applied to the back contact solar cell. The conductive material includes, but is not limited to, conductive paste, solder, solder ink, conductive ink, isotropic conductive adhesive, anisotropic conductive adhesive, and bulk or cylindrical metal and / or metal alloy conductors.

[0088] Conductive materials are applied to the positive and negative electrodes of the back-contact solar cell, or to the p-type and n-type doped diffusion regions, through methods such as screen printing, inkjet printing, and coating, to form continuous contact lines or electrical contacts.

[0089] The back-contact solar cells can be arranged first, and then conductive material can be applied to the entire panel. This process can be carried out using industrialized, low-cost screen printing, which is highly efficient. Alternatively, conductive material can be applied to each back-contact solar cell first, and then the panels can be arranged.

[0090] Step 102: Lay out the welding strip and pre-bond it to the electrode of the battery cell.

[0091] Solder ribbons are laid on the positive and negative electrodes of the back-contact solar cells, or on the p-type and n-type doped diffusion regions. The solder ribbons form a pre-bond with the cells through a conductive material. This is achieved by using a paste-like conductive slurry or solder paste as the conductive material; the viscosity of the conductive material provides initial bonding force, facilitating subsequent cell string arrangement and interconnection, and protecting the solder ribbons from detachment or misalignment during processing. To achieve a better pre-bond effect, stronger bonding force can be generated through heating or localized heating.

[0092] Optionally, the pre-bonding of the solder ribbon to the cell electrode is achieved by preheating the cell. The conductive material on the cell shrinks upon heating, and a portion of it solidifies, thereby strengthening the bond and fixation of the solder ribbon. The cell heating temperature is between 60℃ and 180℃. Alternatively, the solder ribbon is preheated and placed on the surface of the cell, contacting the conductive material on the cell surface. The heat from the solder ribbon causes partial shrinkage and solidification of the conductive material, forming a pre-bonding between the solder ribbon and the cell.

[0093] Preheating allows the solder ribbons in the conductive adhesive film to form an initial bond with the positive and negative electrodes or p-type and n-type doped diffusion regions of the solar cell through the conductive material applied to the cell. On one hand, since a paste-like conductive slurry or solder paste can be used as the conductive material, the viscosity of the conductive material provides initial adhesion, facilitating subsequent cell string arrangement and interconnection. On the other hand, preheating also softens the polymer protrusions on the adhesive film and bonds them to the solar cell, thus fixing the solder ribbons. Without preheating, the solder ribbons laid on the cell will move, resulting in defects such as short circuits or poor contact in the manufactured battery module, leading to module scrap.

[0094] Step 103: Lay out the pre-encapsulation film and cover plate, and laminate them to form a back contact solar cell module.

[0095] Specifically, the cover plate, front encapsulation material, solar cells, rear encapsulation film, and backsheet are sequentially stacked and fed into a laminator for lamination. The lamination process parameters are set according to the vulcanization characteristics of the encapsulation material, such as EVA, and are generally laminated at 140℃~150℃ for 5~15 minutes. After lamination, the metal frame (usually an aluminum frame) and junction box are installed, and power testing, PL testing, and appearance inspection are performed to obtain the back contact solar cell module.

[0096] Optionally, during the lamination process, vacuum extraction can be performed to completely remove air from the battery module, further improving the reliability of the back-contact solar cell module. This is not specifically limited in this embodiment of the invention.

[0097] In the embodiments of the present invention, the corresponding or identical parts of the conductive adhesive film, backsheet, and back contact solar cell assembly can be referenced to each other and can achieve the same or similar beneficial effects.

[0098] The conductive adhesive film, backsheet, and back-contact solar cell module provided in this invention all involve pressing polymer protrusions or adhesive films into the gaps between adjacent solder strips to fill the area between the electrodes of the solar cell. This process squeezes out the air in the area between the electrodes, effectively eliminating the air in the area between the electrodes of the solar cell before lamination. This results in a back-contact solar cell module with virtually no air bubbles, improving module reliability. Simultaneously, during lamination, the back-contact adhesive film at the protrusions and the encapsulation film at other locations soften and flow, or the polymer protrusions and adhesive films undergo a cross-linking reaction, forming a defect-free integrated structure with good adhesion, further enhancing module reliability. It can be deduced that the conductive adhesive film, backsheet, and back-contact solar cell module employ similar technical solutions and principles to improve module reliability, achieving the same or similar technical effects, demonstrating a unique characteristic among the three.

[0099] It should be noted that, for the sake of simplicity, the method embodiments are all described as a series of actions. However, those skilled in the art should understand that the embodiments of this application are not limited to the described order of actions, because according to the embodiments of this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily essential to the embodiments of this application.

[0100] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0101] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. An electrically conductive adhesive film, characterized by, For use in back-contact solar cell modules, the conductive adhesive film includes: an adhesive film and a plurality of solder strips embedded on one side of the adhesive film; on the side of the adhesive film where the solder strips are disposed, polymer protrusions are disposed between adjacent solder strips; The back-contact solar cell assembly includes a cell, the cell includes a plurality of electrodes, and the solder strip is directly opposite the electrodes; The polymer protrusions are either strip-shaped or dot-shaped. When the polymer protrusion is strip-shaped, the width of the polymer protrusion is 15% to 80% of the main grid spacing width of the solar cell; When the polymer protrusions are dot-shaped protrusions, the diameter of the polymer protrusions is 1-5 mm; The polymer protrusions are made of the same material as the adhesive film, and the polymer protrusions are integrally formed with the adhesive film; A release layer is provided on the side of the adhesive film away from the solder strip; the polymer protrusions and the adhesive film are heat-pressed together with the release layer.

2. The conductive adhesive film according to claim 1, wherein The height of the polymer protrusion is less than or equal to the height of the solder strip protruding from the adhesive film.

3. The conductive paste film according to claim 1 or 2, characterized by When the polymer protrusion is in the form of a strip, the width of the polymer protrusion is 3-10 mm.

4. The conductive adhesive film according to claim 1, wherein The polymer protrusions are either continuously extending strip-shaped protrusions or discontinuously extending strip-shaped protrusions.

5. The electrically conductive adhesive film of claim 1, wherein When the polymer protrusions are dot-shaped, the spacing between adjacent polymer protrusions is 2-6 mm in the direction parallel to the extension of the solder strip.

6. The conductive paste film according to claim 1 or 2, wherein The thickness of the release layer is 50-300 μm.

7. The conductive paste film according to claim 1 or 2, wherein The polymer protrusions are selected from at least one of the following: ethylene-vinyl acetate copolymer, ethylene-octene copolymer, polyvinyl butyral, and silicone.

8. A back contact solar cell module, characterized by, include: The cover plate, front encapsulation material, battery cell, rear encapsulation film, and backplate are stacked in sequence. The backing film has several solder strips embedded on its light-facing surface; the backplate includes a backplate substrate and several protrusions spaced apart on the light-facing surface of the backplate substrate; the protrusions and the solder strips are distributed alternately; the protrusions on the light-facing surface of the backplate deform and press the backing film at the protrusions into the gaps between adjacent solder strips by squeezing the backing film.

9. The back contact solar cell module according to claim 8, wherein, The back plate comprises a protrusion unit consisting of one or several protrusions arranged at intervals, and includes several protrusion units spaced apart on the light-facing surface of the back plate substrate.

10. The back contact solar cell module according to claim 9, wherein The height of the protrusion is 20-200 μm.

11. Back contact solar cell module according to claim 9 or 10, characterized in that The protrusions are either strip-shaped or dot-shaped. When the protrusion is a strip-shaped protrusion, the width of the protrusion is 3-10 mm; When the protrusion is a dotted protrusion, the diameter of the protrusion is 1-5 mm.

12. The back contact solar cell module according to claim 11, wherein, When the protrusion is a dot-shaped protrusion, the distance between adjacent protrusions within the same protrusion unit is 2-6 mm.

13. The back contact solar cell module according to claim 9 or 10, characterized in that, The material of the backplate substrate is glass.

14. The back contact solar cell module according to claim 9 or 10, characterized in that, The protrusion is integrally formed with the back plate substrate; Alternatively, if the backing substrate is a glass backing substrate, the raised printing is sintered onto the glass backing substrate.

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