A film with a film covering and interconnection integrated and a preparation method thereof, a main-grid-free photovoltaic module and application

Abstract

This invention relates to the field of photovoltaic module encapsulation technology, specifically to a laminated interconnect film and its preparation method, a grid-less photovoltaic module, and its applications. The laminated interconnect film sequentially comprises: an upper surface layer, an intermediate functional layer, and a lower adhesive layer stacked together; the upper surface layer has a melting point of 80-100℃; the intermediate functional layer contains coupling agent-modified nano-silica and conductive fillers dispersed within it; the lower adhesive layer has a melting point of 60-80℃; and a metal wire positioning groove is provided on the first surface. This invention, through the synergistic design of the three functional materials and the pre-set positioning groove structure, achieves precise positioning and reliable fixation of the metal interconnect wires, significantly reducing contact resistance to below 0.1Ω, increasing the module fill factor to above 83%, and simultaneously reducing the bubble generation rate after lamination to below 0.5%. This effectively solves key technical challenges in grid-less module encapsulation, reduces silver paste usage by more than 45%, increases module power by more than 3%, and has promising industrial application prospects.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module packaging technology, and more specifically, to a film-coated interconnect integrated film and its preparation method, a gridless photovoltaic module, and its applications. Background Technology

[0002] As the photovoltaic industry continues its pursuit of cost reduction and efficiency improvement, cell technology is developing towards busbar-less (OBB) technology. OBB technology significantly reduces silver paste usage (up to 45% in HJT cells) by eliminating the main grid lines on the cell surface, while also shortening carrier transport distance and increasing module power. However, the industrial application of OBB technology presents new challenges to module packaging processes: traditional welding methods are no longer suitable for busbar-less structures, and are being replaced by film-coated interconnect technology.

[0003] Film-coated interconnect technology uses a special "skin film" or "integrated film" to pre-fix metal interconnect wires onto the solar cell, and then achieves a robust electrical connection and mechanical encapsulation through a lamination process. However, existing film-coating solutions still have the following shortcomings: 1. The bonding strength between traditional adhesive film and metal wire is insufficient, and bubbles or delamination are easily generated after lamination, which affects the long-term reliability of the component. 2. High contact resistance between the metal wire and the solar cell affects the module's fill factor and output power; 3. The process window is narrow and it is sensitive to parameters such as lamination temperature and pressure, which is not conducive to large-scale production; 4. It cannot simultaneously achieve high bonding strength in interconnected areas and high light transmittance in non-interconnected areas.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a film-coated interconnected integrated film and its preparation method, a gridless photovoltaic module and its application, so as to solve the defects of the prior art.

[0006] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: One aspect of the present invention relates to a laminated interconnect film, the laminated interconnect film comprising: a first surface and a second surface; and sequentially comprising, from the first surface to the second surface: an upper surface layer, an intermediate functional layer and a lower adhesive layer, stacked together; wherein, the melting point of the upper surface layer is 80~100℃; the intermediate functional layer contains coupling agent-modified nano-silica and conductive filler dispersed therein; the melting point of the lower adhesive layer is 60~80℃; and a metal wire positioning groove is provided on the first surface, the metal wire positioning groove being used to position the metal interconnect wire directly above the fine grid lines on the surface of the battery cell, and to extend the metal interconnect wire along the parallel direction of the fine grid lines.

[0007] The aforementioned film-coated interconnected integrated film has a three-layer composite structure. The upper layer has a low melting point and preferentially melts and flows in the early stage of lamination, which helps with degassing and filling. The middle functional layer contains modified nano-silica and conductive fillers, which not only improves the bonding strength between the film and the metal wires, but also reduces the contact resistance. The lower adhesive layer has the lowest melting point and preferentially bonds to the surface of the battery cell, ensuring accurate alignment and reliable contact between the metal wires and the fine grid lines.

[0008] Another aspect of the present invention relates to a method for preparing the aforementioned film-coated interconnected integrated film, comprising the following steps: (a) melting, co-extruding and casting an upper surface material, an intermediate functional layer material and a lower adhesive layer material to obtain a precursor film; (b) pressing and cooling the precursor film to form a metal wire positioning groove.

[0009] This preparation method involves melting, co-extruding, and casting the upper surface layer material, the middle functional layer material, and the lower adhesive layer material into a film, and simultaneously pressing and cooling the film using a cooling roller with protrusions. This achieves integrated molding of the multi-layer structure and the metal wire positioning groove, making the process simple and controllable. The integrated film prepared by this method has a wide lamination process window, significantly improving its adaptability to lamination temperature and pressure, which is beneficial for large-scale production.

[0010] Another aspect of the present invention relates to a gridless photovoltaic module, which is mainly prepared by laminating glass, an integrated film embedded with metal interconnect wires, solar cells, the integrated film with film interconnects and a backsheet; wherein the integrated film with embedded metal interconnect wires includes: the integrated film with film interconnects and metal interconnect wires embedded in metal wire positioning grooves.

[0011] The aforementioned gridless photovoltaic module precisely fixes the metal interconnect wires directly above the fine grid lines of the solar cells. After lamination, high-precision alignment and low-resistance contact between the metal interconnect wires and the fine grid lines are achieved, ensuring the reliability and long-term stability of the electrical connection. This module effectively reduces the amount of silver paste used while increasing the output power and has excellent aging resistance, demonstrating outstanding comprehensive performance and promising prospects for industrial applications.

[0012] Another aspect of the present invention relates to the application of the aforementioned integrated film-coated interconnect in the fabrication of gridless photovoltaic modules.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The film-coated interconnection integrated film provided by the present invention adopts a three-layer composite structure of upper surface layer, middle functional layer and lower adhesive layer. It utilizes the step difference of melting point of each layer to realize step melting and synergistic effect in the lamination process, effectively solving the problems of incomplete degassing and insufficient bonding strength of traditional adhesive films. By pre-setting metal wire positioning grooves on the first surface, the metal interconnect wires are accurately positioned directly above the fine grid lines of the battery cell and kept parallel, fundamentally avoiding poor contact caused by metal wire deviation. The coupling agent modified nano-silica dispersed in the middle functional layer significantly enhances the interfacial bonding force between the adhesive film and the metal wires, while the micro-conductive pathways formed by the conductive filler during the lamination process effectively reduce the contact resistance, thereby improving the fill factor and output power of the module, while taking into account the light transmittance difference between the interconnected area and the non-interconnected area.

[0014] (2) The preparation method of the film-coated interconnected integrated film provided by the present invention is to melt, co-extrude and cast the upper surface material, the middle functional layer material and the lower adhesive layer material into a film, and use a cooling roller with protrusions to simultaneously press and cool and shape it, thereby realizing the integrated molding of the multi-layer structure and the metal wire positioning groove. The process is simple and controllable. The integrated film prepared by this method has a wide lamination process window and significantly improves the adaptability to lamination temperature and pressure, which is conducive to large-scale production.

[0015] (3) The gridless photovoltaic module provided by the present invention uses the above-mentioned film-coated interconnection integrated film to precisely fix the metal interconnect wires directly above the fine grid lines of the battery cell. After lamination, the high-precision alignment and low-resistance contact between the metal interconnect wires and the fine grid lines are achieved, ensuring the reliability and long-term stability of the electrical connection. The module effectively reduces the amount of silver paste used while improving the output power and has excellent aging resistance, with outstanding comprehensive performance and industrial application prospects. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the integrated film with film coating provided by the present invention. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope 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. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0019] One aspect of the present invention relates to a laminated interconnected integrated film, such as Figure 1 As shown, the film-coated interconnect film includes: a first surface and a second surface; from the first surface to the second surface, it includes: an upper surface layer, an intermediate functional layer and a lower adhesive layer stacked together; The melting point of the upper surface layer is 80~100℃ (for example, it can be any one of 80℃, 85℃, 90℃, 95℃ or 100℃ or a range between any two). The intermediate functional layer contains coupling agent-modified nano-silica and conductive filler dispersed in it. The melting point of the lower adhesive layer is 60~80℃ (for example, it can be any one of 60℃, 65℃, 70℃, 75℃ or 80℃ or a range between any two). A metal wire positioning groove is provided on the first surface. The metal wire positioning groove is used to position the metal interconnect wire directly above the fine grid line on the surface of the battery cell and to make the metal interconnect wire extend in the parallel direction of the fine grid line.

[0020] The aforementioned film-coated interconnected integrated film adopts a three-layer composite structure. The upper surface layer has a low melting point and preferentially melts and flows in the early stage of lamination, which helps with degassing and filling. The middle functional layer contains modified nano-silica and conductive filler, which not only improves the bonding strength between the adhesive film and the metal wires, but also reduces the contact resistance. The lower adhesive layer has the lowest melting point and preferentially bonds to the surface of the battery cell, ensuring accurate alignment and reliable contact between the metal wires and the fine grid lines.

[0021] The metal wire positioning groove formed by the cooling roller imprinting achieves precise positioning of the metal interconnect wire, solves the problem of poor contact caused by metal wire misalignment in the OBB process, and reduces the bubble generation rate to below 0.5% after lamination.

[0022] The conductive filler in the intermediate functional layer forms a micro-conductive path during the lamination process, which reduces the contact resistance between the metal wire and the fine grid line of the battery cell to below 0.1Ω and increases the module fill factor to over 83%.

[0023] Furthermore, the thickness of the upper surface layer is 20~50μm, including but not limited to a point value or a range between any two of 20μm, 25μm, 30μm, 35μm, 40μm, 45μm or 50μm.

[0024] Furthermore, the upper surface layer comprises: an upper surface layer matrix and antioxidants and light stabilizers dispersed in the upper surface layer matrix; the upper surface layer matrix comprises: thermoplastic polyolefin (TPO).

[0025] Further, the mass ratio of the upper surface matrix, the antioxidant, and the light stabilizer is 100:0.2~0.8:0.1~0.4. The types of antioxidants and light stabilizers are not limited; conventional antioxidants and light stabilizers in the art can be used. For example, antioxidants include pentaerythritol tetrapropionate, and light stabilizers include benzophenone-based UVA stabilizers and / or benzoic acid esters.

[0026] Furthermore, the thickness of the intermediate functional layer is 100~300μm, including but not limited to a point value of any one of 100μm, 150μm, 200μm, 250μm or 300μm or a range between any two.

[0027] Furthermore, the matrix of the intermediate functional layer includes ethylene-vinyl acetate copolymer (EVA).

[0028] Furthermore, the mass ratio of the matrix of the intermediate functional layer, the coupling agent-modified nano-silica, and the conductive filler is 100:3~8:0.5~2, including but not limited to 100:3:2, 100:5:1.5, 100:7:1, or 100:8:0.5.

[0029] Further, the preparation method of the coupling agent modified nano-silica includes: dispersing nano-silica in a solvent, adding a silane coupling agent, reacting at 60~70℃ (for example, it can be any one of 60℃, 63℃, 65℃, 68℃ or 70℃ or any range between two) for 2~4h (for example, it can be any one of 2h, 2.5h, 3h, 3.5h or 4h or any range between two), and filtering and drying.

[0030] Furthermore, the average particle size of the nano-silica is 20~50nm, including but not limited to a point value of any one of 20nm, 30nm, 40nm or 50nm or a range between any two.

[0031] Furthermore, the silane coupling agent includes, but is not limited to, KH-570.

[0032] Furthermore, the solvent includes, but is not limited to, ethanol.

[0033] Furthermore, the conductive filler includes at least one of silver-plated glass microspheres, conductive carbon black, or graphene.

[0034] Furthermore, the thickness of the lower adhesive layer is 20~50μm, including but not limited to a point value of any one of 20μm, 30μm, 40μm or 50μm or a range between any two.

[0035] Furthermore, the raw material of the lower adhesive layer includes polyolefin elastomer (POE).

[0036] Furthermore, the depth of the metal wire positioning groove is 50~150μm (for example, it can be any one of 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm or 150μm or any range between two), the spacing between two adjacent metal wire positioning grooves is 0.5~2.0mm (for example, it can be any one of 0.5mm, 1.0mm, 1.5mm or 2.0mm or any range between two), which is consistent with the spacing between two adjacent fine grid lines on the solar cell, and the groove width matches the diameter of the metal interconnect wire.

[0037] Furthermore, the cross-sectional shape of the metal wire positioning groove includes any one of trapezoidal, semi-circular, or rectangular shapes.

[0038] Another aspect of the present invention relates to a method for preparing the aforementioned coated interconnected integrated film, comprising the following steps: (a) The upper surface material, the middle functional layer material and the lower adhesive layer material are melted, co-extruded and cast into a film to obtain a precursor film; (b) The precursor film is imprinted and cooled to form a metal wire positioning groove.

[0039] The preparation method described above involves melting, co-extruding, and casting the upper surface layer material, the middle functional layer material, and the lower adhesive layer material into a film, and simultaneously pressing and cooling the film using a cooling roller with protrusions. This achieves integrated molding of the multi-layer structure and the metal wire positioning groove, making the process simple and controllable. The integrated film prepared by this method has a wide lamination process window, significantly improving its adaptability to lamination temperature and pressure, which is beneficial for large-scale production.

[0040] Furthermore, the co-extrusion temperature of the upper surface layer is 150~170℃, including but not limited to any one of 150℃, 155℃, 160℃, 165℃ or 170℃ or any range between two of them. This temperature range ensures sufficient melting, ensures fluidity, and can spread evenly in the die head to form a continuous and defect-free surface layer. Setting a relatively high temperature can reduce its melt viscosity to a level that can match the medium-temperature lower binder layer, ensuring that the three melt layers can be smoothly compounded when they meet in the die head.

[0041] Furthermore, the co-extrusion temperature of the intermediate functional layer is 80~100℃, including but not limited to any one of 80℃, 85℃, 90℃, 95℃ or 100℃ or any range between two of them. This temperature range protects the functional filler and ensures that during co-extrusion, heat from the high-temperature upper surface layer (150℃+) will not be transferred to the low-temperature adhesive layer, effectively preventing unnecessary pre-crosslinking or thermal dissolution of the materials in each layer inside the die, and ensuring a clear three-layer structure.

[0042] Furthermore, the co-extrusion temperature of the lower adhesive layer is 130~150℃, including but not limited to any one of 130℃, 135℃, 140℃, 145℃ or 150℃ or any range between two of them. This temperature range ensures the bonding performance, guarantees that the POE melts completely, has good fluidity, and achieves viscosity matching.

[0043] Furthermore, the cooling and shaping temperature is 20~30℃, including but not limited to any one of 20℃, 23℃, 25℃, 28℃ or 30℃, or any range between two of them.

[0044] Further, the upper surface matrix, the antioxidant, and the light stabilizer are mixed and then extruded and granulated to obtain the upper surface material.

[0045] Further, the matrix of the intermediate functional layer, the coupling agent-modified nano-silica, the conductive filler, the crosslinking agent, and the co-crosslinking agent are mixed, and then melt-blended and extruded granulated using a twin-screw extruder to obtain the intermediate functional layer material; the mass ratio of the matrix of the intermediate functional layer, the crosslinking agent, and the co-crosslinking agent is 100:1~2:0.5~1, including but not limited to 100:1:1, 100:1.5:0.8, or 100:2:0.5.

[0046] Further, the raw materials of the lower adhesive layer, the crosslinking agent and the co-crosslinking agent are mixed and then extruded and granulated to obtain the lower adhesive layer material; the mass ratio of the raw materials of the lower adhesive layer, the crosslinking agent and the co-crosslinking agent is 100:1~1.5:0.4~0.8, including but not limited to 100:1:0.8, 100:1.3:0.6 or 100:1.5:0.8.

[0047] Furthermore, the crosslinking agent includes, but is not limited to, tert-butyl percarbonate-2-ethylhexyl ester (TBEC); the co-crosslinking agent includes, but is not limited to, triallyl isocyanurate (TAIC).

[0048] Furthermore, the wire positioning groove is formed by embossing a cooling roller with protrusions on the surface of the precursor film.

[0049] Furthermore, the cooling and shaping process further includes: winding.

[0050] Another aspect of the present invention relates to a gridless photovoltaic module, which is mainly prepared by laminating glass, an integrated film embedded with metal interconnect wires, solar cells, the integrated film with film interconnect and a back sheet. The integral film embedded with metal interconnect wires includes: the film-coated interconnect integral film and the metal interconnect wires embedded in the metal wire positioning groove.

[0051] The aforementioned gridless photovoltaic module uses a laminated interconnect film to precisely fix metal interconnect wires directly above the fine grid lines of the solar cells. After lamination, high-precision alignment and low-resistance contact between the metal interconnect wires and the fine grid lines are achieved, ensuring the reliability and long-term stability of the electrical connection. This module effectively reduces the amount of silver paste used while increasing output power and has excellent aging resistance, demonstrating outstanding comprehensive performance and promising prospects for industrial applications.

[0052] Furthermore, the lamination process is performed at a temperature of 140~160℃ (e.g., any value or range between 140℃, 145℃, 150℃, 155℃, or 160℃), a pressure of 0.5~1.5 atm (e.g., any value or range between 0.5 atm, 1.0 atm, or 1.5 atm), and a time of 10~15 min (e.g., any value or range between 10 min, 13 min, or 15 min). The specific three-layer material layering and melting characteristics of the laminated interconnected membrane enable good encapsulation within a wide lamination temperature range (140~160℃) and pressure range (0.5~1.5 atm), significantly improving process adaptability.

[0053] Furthermore, the gridless photovoltaic module comprises: a plurality of solar cells.

[0054] Furthermore, the metal interconnect wire is embedded in the metal wire positioning groove and is pressed into contact with the fine grid lines on the surface of the battery cell through the lower adhesive layer; the laminated interconnect integrated film covers the surface of the battery cell, and after lamination, the metal interconnect wire forms an electrical connection with the battery cell, while simultaneously encapsulating and fixing the battery cell.

[0055] Further, the metal interconnect wire comprises: a round or flat copper wire with a diameter of 200~400μm (for example, it can be any one of 200μm, 250μm, 300μm, 350μm or 400μm or any range between two), and the surface is coated with a low melting point alloy coating, wherein the melting point of the low melting point alloy is 138~160℃ (for example, it can be any one of 138℃, 145℃, 150℃, 155℃ or 160℃ or any range between two).

[0056] Furthermore, the solar cell includes any one of the following: HJT cell without a main grid structure, TOPCon cell without a main grid structure, or BC cell without a main grid structure. The spacing of the fine grid lines on the surface of the solar cell is 0.5~2.0mm (for example, it can be any point value or any range between 0.5mm, 1.0mm, 1.5mm or 2.0mm, but not limited to it), and the width of the fine grid lines is 20~50μm (for example, it can be any point value or any range between 20μm, 30μm, 40μm or 50μm, but not limited to it).

[0057] Another aspect of the present invention relates to the application of the aforementioned integrated film-coated interconnect in the fabrication of gridless photovoltaic modules.

[0058] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0059] Example 1 The integrated film for interconnection provided in this embodiment includes: a first surface and a second surface; from the first surface to the second surface, it includes: an upper surface layer, an intermediate functional layer and a lower adhesive layer stacked together. The upper surface layer has a melting point of 90℃ and a thickness of 35μm. The upper surface layer includes: an upper surface layer matrix and antioxidants and light stabilizers dispersed in the upper surface layer matrix; the upper surface layer matrix includes: thermoplastic polyolefin (TPO, melt index 7g / 10min). The intermediate functional layer contains coupling agent-modified nano-silica and conductive filler, with a thickness of 200 μm; the matrix of the intermediate functional layer includes: ethylene-vinyl acetate copolymer (EVA, VA content of 28 wt%, melt index of 15 g / 10 min). The lower adhesive layer has a melting point of 70℃ and a thickness of 35μm; the raw materials of the lower adhesive layer include: polyolefin elastomer (POE, melt index 5g / 10min). A metal wire positioning groove is provided on the first surface. The metal wire positioning groove is used to position the metal interconnect wire directly above the fine grid line on the surface of the battery cell and to make the metal interconnect wire extend in the parallel direction of the fine grid line. The depth of the metal wire positioning groove is 100μm and the distance between two adjacent metal wire positioning grooves is 1.2mm.

[0060] The method for preparing the laminated interconnected integrated membrane provided in this embodiment includes the following steps: 1. Top surface material: 100kg of TPO resin, with 0.5kg of antioxidant 1010 and 0.3kg of light stabilizer 770 added, mixed and then extruded into granules; 2. Intermediate functional layer material: Nano silica modification: Take 10 kg of nano silica with an average particle size of 30 nm, disperse it in 100 L of ethanol, add 1.5 kg of silane coupling agent KH-570, react at 65 °C for 3 hours, filter, wash and dry to obtain coupling agent modified nano silica. 100 kg of EVA resin, 5 kg of coupling agent-modified nano-silica, 1 kg of silver-plated glass microspheres (average particle size 10 μm), 1.5 kg of crosslinking agent tert-butyl percarbonate-2-ethylhexyl ester (TBEC), and 0.8 kg of co-crosslinking agent triallyl isocyanurate (TAIC) were mixed and melt co-extruded in a twin-screw extruder (temperature 90℃) and granulated. 3. Lower adhesive layer material: 100kg of POE resin, 1.2kg of crosslinking agent TBEC and 0.6kg of TAIC, mixed and granulated; 4. Co-extrusion molding: Add the three types of granules to a three-layer co-extrusion casting machine and set the temperature of each layer: 160℃ for the upper surface layer, 90℃ for the middle functional layer, and 140℃ for the lower adhesive layer; after the melt flows out through the die head, it is pressed through a cooling roller with raised surfaces (raised height 100μm, width 300μm, spacing 1.2mm), the temperature of the cooling roller is 25℃, and it is pulled and wound up to obtain an integrated film product.

[0061] Example 2 It is basically the same as Example 1, except that the conductive filler in the intermediate functional layer is graphene, the mass ratio of EVA resin to graphene is 100:0.8, the diameter of the metal interconnect wire is adjusted to 250μm (flat), and the depth of the metal wire positioning groove is 80μm.

[0062] Example 3 The method for preparing a grid-free photovoltaic module provided in this embodiment uses the integrated film prepared in Example 1 and includes the following steps: 1. Take HJT solar cells without main grids (size 182mm×182mm, fine grid line spacing is 1.2mm, fine grid line width is 30μm) and arrange them according to the design; 2. Take the above-mentioned integrated film, cut it to a suitable size, and embed a 300μm diameter plated copper wire (surface coated with SnBi low melting point alloy, melting point 145℃) into the metal wire positioning groove of the integrated film. 3. Lay the layers in the following order: glass - integrated film (with metal wires) - battery cell - integrated film - backsheet; 4. Place the laminator in the laminator, set the lamination temperature to 150℃, the lamination time to 12 minutes, and the lamination pressure to 1.0 atm; 5. After lamination, the modules are framed and wired to obtain the finished photovoltaic modules.

[0063] Performance testing: Contact resistance test: The four-probe method was used for testing, and the contact resistance between the metal wire and the battery cell was 0.08Ω.

[0064] Module electrical performance testing (Standard Test Conditions STC): Module power is increased by 3.2% compared to conventional welding process, and the fill factor is 83.5%.

[0065] Aging test: After TC200 (-40℃~85℃ 200 cycles) and DH1000 (85℃ / 85%RH 1000h) tests, the power degradation of the module was 1.8% and 2.1% respectively, with no visible delamination or bubbles.

[0066] Example 4 It is basically the same as Example 3, except that the battery cell uses a gridless TOPCon battery with a fine grid line spacing of 1.5mm.

[0067] Comparative Example 1 (Structure without positioning groove) This method is essentially the same as Example 1, except that the metal wire positioning grooves are not imprinted on the surface of the integrated film; instead, the metal wires are directly laid on the film surface. The method for fabricating the gridless photovoltaic module provided in Example 3 is used.

[0068] The results showed that some metal wires shifted after lamination, with a maximum shift of 0.3 mm, resulting in poor contact of some fine grid lines; the average contact resistance was 0.25 Ω, with a maximum of 0.45 Ω; the fill factor was 81.2%; after TC200 testing, bubbles appeared in some areas, and the power attenuation reached 5.8%.

[0069] Comparative Example 2 (without conductive filler) This is essentially the same as Example 1, except that no conductive filler is added to the intermediate functional layer. The fabrication method for the gridless photovoltaic module provided in Example 3 is used.

[0070] The results showed that the contact resistance was 0.18Ω, the fill factor was 82.0%, and the module power increased by 1.5%. After the DH1000 test, the contact resistance increased to 0.35Ω and the power decreased by 3.8%.

[0071] Comparative Example 3 (Single-layer structure) A conventional EVA film (400 μm thick) was used, and metal wires were directly laid and then laminated. The fabrication method of the gridless photovoltaic module provided in Example 5 was adopted.

[0072] The results showed that the bonding strength between the metal wire and the adhesive film was insufficient, and air bubbles appeared in some areas after lamination; the contact resistance was unstable, averaging 0.30Ω; the fill factor was 80.5%; and the power attenuation reached 7.2% after aging test.

[0073] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laminated interconnected integrated membrane, characterized in that, The membrane-coated interconnection film includes: a first surface and a second surface; from the first surface to the second surface, it includes: an upper surface layer, an intermediate functional layer and a lower adhesive layer stacked together; The melting point of the upper surface layer is 80~100℃; The intermediate functional layer contains coupling agent-modified nano-silica and conductive filler dispersed in it. The melting point of the lower adhesive layer is 60~80℃; A metal wire positioning groove is provided on the first surface. The metal wire positioning groove is used to position the metal interconnect wire directly above the fine grid line on the surface of the battery cell and to make the metal interconnect wire extend in the parallel direction of the fine grid line.

2. The integrated film with film coating according to claim 1, characterized in that, Includes at least one of the following technical features: (1) The thickness of the upper surface layer is 20~50μm; (2) The upper surface layer includes: an upper surface layer matrix and antioxidants and light stabilizers dispersed in the upper surface layer matrix; the upper surface layer matrix includes: thermoplastic polyolefin.

3. The integrated film with film coating and interconnection according to claim 1, characterized in that, Includes at least one of the following technical features: (1) The thickness of the intermediate functional layer is 100~300μm; (2) The matrix of the intermediate functional layer includes: ethylene-vinyl acetate copolymer; (3) The mass ratio of the matrix of the intermediate functional layer, the coupling agent modified nano silica and the conductive filler is 100:3~8:0.5~2.

4. The integrated film with film coating according to claim 1, characterized in that, Includes at least one of the following technical features: (1) The thickness of the lower adhesive layer is 20~50μm; (2) The raw material of the lower adhesive layer includes: polyolefin elastomer; (3) The depth of the metal wire positioning groove is 50~150μm, and the distance between two adjacent metal wire positioning grooves is 0.5~2.0mm.

5. The method for preparing the coated interconnected integrated membrane according to any one of claims 1 to 4, characterized in that, Includes the following steps: (a) The upper surface material, the middle functional layer material and the lower adhesive layer material are melted, co-extruded and cast into a film to obtain a precursor film; (b) The precursor film is imprinted and cooled to form a metal wire positioning groove.

6. The method for preparing the coated interconnected integrated membrane according to claim 5, characterized in that, Includes at least one of the following technical features: (1) The co-extrusion temperature of the upper surface layer is 150~170℃; (2) The co-extrusion temperature of the intermediate functional layer is 80~100℃; (3) The co-extrusion temperature of the lower adhesive layer is 130~150℃.

7. The method for preparing the coated interconnected integrated membrane according to claim 5, characterized in that, The cooling and shaping temperature is 20~30℃.

8. A gridless photovoltaic module, characterized in that, It is mainly prepared by laminating glass, an integrated film embedded with metal interconnect wires, a battery cell, the film-coated interconnect integrated film as described in any one of claims 1 to 4, and a back sheet; The integral film embedded with metal interconnect wires includes: the film-coated interconnect integral film according to any one of claims 1 to 4 and the metal interconnect wires embedded in the metal wire positioning groove.

9. The method for preparing a photovoltaic module according to claim 8, characterized in that, The lamination process is carried out at a temperature of 140~160℃, a pressure of 0.5~1.5 atm, and a time of 10~15 min.

10. The application of the film-coated interconnected integrated film as described in any one of claims 1 to 4 in the preparation of a gridless photovoltaic module.

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