A photovoltaic module and method of manufacturing the same

Abstract

The application relates to a photovoltaic module and a manufacturing method thereof. The photovoltaic module comprises a cell string, the cell string comprises a plurality of cell pieces, the plurality of cell pieces are arranged side by side along the length direction of the photovoltaic module; a solder strip is arranged on one side of the cell piece along the thickness direction of the photovoltaic module and used for connecting adjacent cell pieces; and a film layer comprises a plurality of film strips arranged side by side, the film strip is arranged on the cell piece and covers a corresponding solder strip; wherein the solder strip is a first conductor with a tin layer or a first conductor without a tin layer; when the solder strip is the first conductor with the tin layer, the thickness of the tin layer is less than or equal to 5 mu m. The photovoltaic module can improve the output power of the photovoltaic module without affecting the light receiving area, and meanwhile, the welding stability is improved.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a photovoltaic module and a method for manufacturing the same. Background Technology

[0002] Solar energy modules can directly convert solar radiation energy into electrical energy, mainly based on the photovoltaic effect of crystalline silicon. When the photons of sunlight are absorbed by the semiconductor crystalline silicon, electron-hole pairs are generated. When these electron-hole pairs reach the pn junction composed of p-type and n-type crystalline silicon, they are separated to both sides of the pn junction by the junction electric field. When an external load is connected, a photocurrent is formed, and electrical energy is output.

[0003] Interconnection welding of solar cells is one of the core processes in solar module assembly. In some methods, the diameter of the solder strip is reduced to decrease lateral current transmission loss and series resistance, thereby improving the overall power output of the solar module. However, this method can easily lead to unstable local contact welds and result in incomplete soldering. Summary of the Invention

[0004] This application provides a photovoltaic module and its manufacturing method, which can improve the output power of the photovoltaic module without affecting the light-receiving area of ​​the photovoltaic module, while also improving the welding stability.

[0005] This application provides a photovoltaic module, the photovoltaic module comprising: A battery string, comprising multiple battery cells arranged side-by-side along the length of the photovoltaic module; A solder ribbon, located along the thickness direction of the photovoltaic module on one side of the solar cell, connecting adjacent solar cells; and The coating includes multiple parallel film strips, which are disposed on the battery cell and cover a corresponding solder strip. Wherein, the solder strip is a first conductor with a tin layer or a first conductor without a tin layer; when the solder strip is a first conductor with a tin layer, the thickness of the tin layer is less than or equal to 5µm.

[0006] In one possible implementation, the solder strip is a first conductor with a tin layer, and the projection of the solder strip in the cell along the width direction of the photovoltaic module has a dimension of D mm, where D is 0.15~0.3, and the ratio of the thickness R of the tin layer to D is 1:(30~60).

[0007] In one possible implementation, along the thickness direction of the photovoltaic module, the projection of the film strip in the cell along the width direction of the photovoltaic module is L mm, and the projection of the solder strip in the cell along the width direction of the photovoltaic module is D mm, with the ratio of L / D being (10~20):1.

[0008] In one possible implementation, along the thickness direction of the photovoltaic module, the projection of the film strip into the solar cell has a dimension L of 2.5 mm to 6 mm along the width direction of the photovoltaic module; the light transmittance of the film strip is greater than 85%.

[0009] In one possible implementation, the side of the solar cell facing the solder strip has a plurality of solder joints along the length of the photovoltaic module, and a second conductor is provided between the solder joints and the solder strip, wherein at least a portion of the projection of the second conductor overlaps with the projection of the solder strip.

[0010] In one possible implementation, the second conductor is solder paste or conductive adhesive, and the solder strip is soldered to the solder joint using the solder paste or conductive adhesive.

[0011] In one possible implementation, the solder strip is a copper strip with a tin layer or a pure copper strip.

[0012] This application embodiment also provides a method for manufacturing a photovoltaic module. The photovoltaic module includes a battery string, which includes multiple battery cells, solder ribbons, and a coating. The solder ribbons are located on one side of the battery cells along the thickness direction of the photovoltaic module and connect adjacent battery cells. The coating includes multiple parallel film strips, which are disposed on the battery cells and cover a corresponding solder ribbon. The solder ribbon is either a first conductor with a tin layer or a first conductor without a tin layer. When the solder ribbon is a first conductor with a tin layer, the thickness of the tin layer is less than or equal to 5µm. The method for manufacturing the photovoltaic module includes: The solder strip is placed on the battery cell, and the solder strip is in contact with the battery cell; In a preheated state, the welding strip is used to fix the welding ribbon, and the welding ribbon connects the battery cells into a battery string; An encapsulation layer and a cover plate are provided on both sides of the battery cell to form a laminate. The component to be laminated is laminated, and the solder strip is electrically connected to the battery cell.

[0013] In one possible implementation, the method for manufacturing the photovoltaic module further includes: A second conductor is placed on the solar cell; The solder strip is disposed on the battery cell, and the solder strip is in contact with the second conductor; The second conductor is solder paste or conductive adhesive.

[0014] In one possible implementation, the step of fixing the welding strip using the membrane strip in a preheated state includes: The highest temperature T1 of the preheated battery cell satisfies: 90℃≤T1≤130℃, and the second conductor partially melts; the film strip is attached to one side of the battery cell and covers the welding strip, and the welding strip is at least partially wrapped by the second conductor.

[0015] In one possible implementation, the step of fixing the welding strip using the membrane strip in a preheated state includes: The maximum temperature T1 of the preheated battery cell satisfies: 90℃≤T1≤130℃; the film strip is attached to one side of the battery cell and covers the welding strip.

[0016] In one possible implementation, the highest temperature T2 for heating the part to be laminated satisfies: 140℃≤T2≤160℃; and / or, the heating time t2 for heating the part to be laminated satisfies: 18min≤t2≤25min.

[0017] In one possible implementation, the step of placing the solder strip on the battery cell is as follows: Cut the whole solar cell into at least two separate solar cells; The solder strip is placed on the sectional battery cell.

[0018] The photovoltaic module and its manufacturing method provided in this application include a cell string, a solder ribbon, and a coating. The cell string includes multiple cells arranged side by side, and the solder ribbon is located on one side of the cells, connecting multiple cells. The solder ribbon is either a first conductor with a tin layer or a first conductor without a tin layer. Without obstructing the effective light-receiving area of ​​the cells, the overall cross-sectional area of ​​the solder ribbon remains unchanged, while maximizing the size of the first conductor. This maximized size effectively reduces the resistance of the solder ribbon, reduces power loss during current transmission, improves the current collection efficiency after photoelectric conversion of the cells, and increases the overall output power of the photovoltaic module. Furthermore, the solder ribbon is pre-fixed using a film strip. During manufacturing, the solder ribbon can be welded to the grid electrodes on the cells through a lamination welding process. With the adhesion of the film strip, the solder ribbon and grid electrodes adhere more tightly and have more stable contact, effectively improving the stability and strength of the welded connection. This reduces problems such as displacement and misalignment of the solder ribbon during welding, and also reduces defects such as cell warping, microcracks, and edge chipping caused by traditional high-temperature welding, thus improving the service life of the photovoltaic module.

[0019] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0020] Figure 1 The following are schematic diagrams of the structure of the photovoltaic module provided in this application in some embodiments; Figure 2 Schematic diagrams of the photovoltaic module provided in this application in other embodiments; Figure 3 for Figure 1 , Figure 2 A schematic diagram of the battery string structure in some embodiments; Figure 4 for Figure 3 A schematic diagram of the structure of the battery cells and solder ribbons in some embodiments; Figure 5 for Figure 3 A schematic diagram of the cross-sectional structure of the solder strip in some embodiments; Figure 6 for Figure 3 A schematic diagram of the structure of the welding strip and membrane strip in some embodiments; Figure 7 for Figure 3 A schematic diagram of the structure of the battery cells and solder ribbons in some other embodiments; Figure 8 This is a schematic flowchart illustrating the manufacturing method of the photovoltaic module provided in this application.

[0021] Figure label: 1- Battery string; 10-cell battery; 11-First fine grid; 12-Second fine grid; 13-Insulation part; 14 - Pads; 2-Welding strip; 21-First conductor; 22-Tin layer; 23-Second conductor; 3-First cover plate; 4-First film layer; 5-Second film layer; 6-Second cover plate; 70-Membrane strip.

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation

[0023] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0024] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0025] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0026] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0027] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when it is mentioned that an element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0028] Figure 1 This is a structural schematic diagram of a photovoltaic module in some embodiments. Figure 2 This is a schematic diagram of the structure of a photovoltaic module in some other embodiments. Figure 3 for Figure 1 , Figure 2 The diagram shows the structure of the battery string in some embodiments.

[0029] like Figures 1-3 As shown, the photovoltaic module includes a cell string 1, which comprises multiple solar cells 10 and solder ribbons 2. The solar cells 10 are arranged side-by-side along the length of the photovoltaic module. The solder ribbons 2 are located on one side of the solar cells 10 along the thickness direction of the photovoltaic module, connecting adjacent solar cells 10. The solder ribbons 2 connecting adjacent solar cells 10 means that after the photovoltaic module is operating, current can be transferred between adjacent solar cells 10 through the solder ribbons 2. Each solar cell 10 has a front and a back side; the front side refers to the light-receiving surface of the solar cell 10, and the back side refers to the light-receiving surface of the solar cell 10.

[0030] In this embodiment, the types of solar cells 10 include, but are not limited to, passivated emitter rear cell (PERC), tunnel oxide passivated contact cell (TOPCON), heterojunction with intrinsic thin layer (HIT), back contact cell (BC), and perovskite solar cells (PSC). This embodiment does not specifically limit the type of solar cells 10 in the photovoltaic module.

[0031] For BC cells, the emitter, surface field, and metal electrodes are all located on the back of the cell and are distributed in a cross-directional manner. The front side of the cell 10 uses SiN. x / SiO x The double-layer anti-reflection passivation film ensures that there are no metal electrodes blocking the front of the battery, allowing the battery cell 10 to receive more incident light, reducing optical losses and improving photoelectric conversion efficiency.

[0032] For TOPCon cells, along their thickness direction, the TOPCon cell sequentially includes a silver electrode, a front-surface silicon nitride passivation layer, a boron-doped emitter, an N-type substrate silicon layer, a diffused doped layer, an ultrathin silicon oxide layer, doped polycrystalline silicon, silicon nitride, and the silver electrode. The back of the cell consists of an ultrathin silicon oxide layer (1nm~2nm) and a phosphorus-doped microcrystalline amorphous mixed Si film, which together form a passivation contact structure. This structure can block minority carrier recombination, increasing the cell's open-circuit voltage and short-circuit current. The ultrathin oxide layer allows majority carrier electrons to tunnel into the polycrystalline silicon layer while blocking minority carrier recombination. The excellent passivation effect of the ultrathin silicon oxide and heavily doped silicon film causes band bending on the silicon wafer surface, resulting in a field passivation effect. This significantly increases the probability of electron tunneling, reduces contact resistance, and improves the cell's open-circuit voltage and short-circuit current, thereby increasing the cell's conversion efficiency.

[0033] For HIT cells, along their thickness direction, HIT cells sequentially include a front low-temperature silver electrode, a front conductive film, an N-type amorphous silicon film, an intrinsic amorphous silicon film, an N-type substrate silicon layer, an intrinsic amorphous silicon film, a P-type amorphous silicon film, a back conductive film, and a back low-temperature silver electrode.

[0034] For PERC cells, along their thickness direction, the PERC cell sequentially includes a front surface silver electrode, a front surface silicon nitride passivation layer, a phosphorus emitter layer, a P-type substrate silicon layer, a local aluminum back field, a metallic aluminum back electrode, and a back passivation layer (Al2O3 / SiN). xPERC cells use a passivation film to passivate the back surface, replacing the all-aluminum back surface, which enhances light reflection on the silicon substrate and reduces the recombination rate on the back surface, thus improving the cell efficiency by 0.5%-1%.

[0035] For a perovskite solar cell, along its thickness direction, the perovskite solar cell sequentially includes a substrate material, a conductive thin film, an electron transport layer (titanium dioxide), a perovskite absorption layer (hole transport layer), and a metal cathode. Perovskite materials have a high light absorption coefficient and a long carrier diffusion distance. After the photons absorbed by the perovskite material are converted into electrons, they are easily collected by the electrodes with low loss, thus generating high photogenerated voltage and current, making perovskite exhibit high photoelectric conversion efficiency.

[0036] like Figure 1 and Figure 2 As shown, the photovoltaic module also includes: a first cover plate 3, a first film layer 4, a second film layer 5, and a second cover plate 6. The first cover plate 3 and the first film layer 4 are located on one side of the front of the solar cell 10, and the second film layer 5 and the second cover plate 6 are located on one side of the back of the solar cell 10. The first cover plate 3, the first film layer 4, the second film layer 5, and the second cover plate 6 encapsulate the solar cell string 1 to ensure that the photovoltaic module has high mechanical strength, reduce the impact of hail, wind, mechanical vibration, etc. on the photovoltaic module, improve the sealing performance of the photovoltaic module, and enhance its corrosion resistance and safety.

[0037] Specifically, the first cover plate 3 and the second cover plate 6 can be one of rigid materials such as tempered glass, polyethylene terephthalate (PET), and polycarbonate (PC), or one of flexible materials such as polyvinyl fluoride (PVF), ethylene-tetrafluoroethylene copolymer (ETFE), and polyvinylidene fluoride (PVDF). These materials have high light transmittance, which can improve the photoelectric conversion efficiency of the photovoltaic module and ensure the power output of the photovoltaic module.

[0038] The first film layer 4 and the second film layer 5 can be one of the following materials: ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), polyvinyl butyral (PVB), EVA-POE-EVA co-extruded film (EPE), EVA-POE co-extruded film (EP), thermoplastic polyurethane (TPU).

[0039] like Figure 3 As shown in the embodiments of this application, the solder ribbon 2 is located on one side of the solar cell 10 along the thickness direction of the photovoltaic module, connecting adjacent solar cells 10. Multiple solder joints are provided along the length direction of the photovoltaic module on the side of the solar cell 10 facing the solder ribbon 2, and the solder ribbon 2 is connected to the solder joints on the solar cell 10.

[0040] Figure 4 for Figure 3 The diagram shows the structure of the battery cells and solder strips in some embodiments.

[0041] like Figure 4 As shown, a grid electrode is disposed on the back side of the solar cell 10. The grid electrode includes a first fine grid 11 and a second fine grid 12, which can collect the photocurrent generated by the solar cell 10. One of the first fine grid 11 and the second fine grid 12 is a positive electrode grid, and the other is a negative electrode grid. The first fine grid 11 and the second fine grid 12 extend along a first direction X, and the first fine grid 11 and the second fine grid 12 are alternately arranged along a second direction Y, where the first direction X and the second direction Y intersect. It should be noted that... Figure 5 The thickness settings of the first fine gate 11 and the second fine gate 12 are only for differentiation and do not represent the actual thickness relationship between the first fine gate 11 and the second fine gate 12.

[0042] The grid electrode further includes a first main grid and a second main grid, one of which is a positive main grid and the other is a negative main grid. The first main grid and the second main grid extend along a second direction Y, and are staggered along a first direction X. Taking the first main grid and the first fine grid 11 having the same polarity, and the second main grid and the second fine grid 12 having the same polarity as an example, the first main grid is electrically connected to multiple first fine grids 11, thereby collecting the current collected by the first fine grids 11, and the second main grid is electrically connected to multiple second fine grids 12, thereby collecting the current collected by the second fine grids 12.

[0043] To prevent short circuits caused by contact between gate electrodes of different polarities, the second fine gate 12 is disconnected at the first main gate, and the first fine gate 11 is disconnected at the second main gate. Furthermore, insulating portions 13 are provided on the outer periphery of the disconnection points of the first fine gate 11 and the second fine gate 12. The insulating portion 13 is typically made of insulating adhesive.

[0044] The first and second main gates are provided with pads 14, and the solder strip 2 is connected to the first or second main gate through the pads 14. That is, the solder strip 2 extends along the second direction Y to conduct the current collected by the first and second main gates. It can be understood that the pads 14 can be set at the position in contact with the fine gate, or they can be set between two adjacent fine gates.

[0045] In other embodiments, the back of the cell 10 does not have a first main grid and a second main grid, and the solder strip 2 extending along the second direction Y is directly connected to the first fine grid 11 or the second fine grid 12 to collect the photocurrent collected by the first fine grid 11 or the second fine grid 12 and conduct it out.

[0046] Correspondingly, the second fine gate 12 is disconnected at the solder strip 2 connected to the first fine gate 11, and the first fine gate 11 is disconnected at the solder strip 2 connected to the second fine gate 12 to avoid short circuit. A solder pad 14 is provided at the connection between the first fine gate 11, the second fine gate 12 and the solder strip 2 to ensure reliable connection between the gate electrode and the solder strip 2.

[0047] Correspondingly, an insulating part 13 is provided at the end of the first fine grid 11 that is disconnected at the solder strip 2 connected to the second fine grid 12, and an insulating part 13 is provided at the end of the second fine grid 12 that is disconnected at the solder strip 2 connected to the first fine grid 11, thereby further preventing the occurrence of short circuits.

[0048] In some embodiments, the solder ribbon 2 is a first conductor 21 with a tin-coated layer 22 or a first conductor 21 without a tin layer. In some specific embodiments, the solder ribbon 2 can be a pure copper ribbon or a copper ribbon with a tin layer. Specifically, the temperature of the lamination process can be used to promote the formation of a metallized alloy between the solder ribbon and the grid electrodes on the surface of the solar cell to achieve a solder connection. The cross-section of the solder ribbon 2 can be circular, elliptical, square, trapezoidal, or quasi-square, etc., and is not limited thereto.

[0049] Figure 5 for Figure 3 A schematic diagram of the cross-sectional structure of the solder strip in some embodiments; such as Figure 5 As shown, in some embodiments, the solder ribbon 2 is the first conductor 21 of the tin-coated layer 22, for example, it can be a copper strip with a tin-coated layer. Specifically, the projection of the solder ribbon 2 in the solar cell 10 along the width direction of the photovoltaic module has a dimension of D mm, where D is 0.15~0.3. In specific embodiments, the size of the solder ribbon can be 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm, 0.3mm, or other values ​​within the above range. Controlling the width direction dimension of the solder ribbon, making it narrower, can maximize the light-receiving area of ​​the solar cell, improve the photoelectric conversion efficiency of the photovoltaic module, and reduce the cost of the solder ribbon. However, when the width dimension of the solder ribbon is too small, the structural stability of the solder ribbon decreases, and problems such as cold solder joints are prone to occur.

[0050] like Figure 5As shown, the ratio of the tin layer thickness R to the solder strip width D is 1:(30~60), specifically 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, or other values ​​within the above range, which are not limited here. The tin layer thickness accounts for a very small proportion of the total width of the solder strip, making the tin layer attached to the surface of the first conductor extremely thin. This allows the overall cross-sectional area of ​​the solder strip to remain unchanged without obstructing the effective light-receiving area of ​​the solar cell 10. The conductivity of tin is lower than that of the first conductor. The extremely thin tin layer can maximize the radial or width dimension of the first conductor, resulting in a stronger overall current-carrying capacity of the solder strip and improving the overall output power of the photovoltaic module.

[0051] Furthermore, the extremely thin tin layer 22 can significantly reduce tin usage, lowering the production cost of photovoltaic modules. With the same overall cross-sectional area of ​​the solder strip, an increase in the thickness of the tin layer means a decrease in the width of the first conductor. For example, with copper strips, the diameter of the copper strip becomes smaller, affecting the output power of the photovoltaic module; or it can lead to a reduction in the light-receiving area of ​​the solar cells, resulting in a decrease in photoelectric conversion efficiency. Moreover, when the tin layer on the surface of the first conductor becomes thicker, defects such as tin buildup, bridging, and cold solder joints may occur during the soldering process. This application controls the ratio of the tin layer thickness R to the width D of the solder strip within the aforementioned range, balancing the overall output power and the light-receiving area, maximizing the output power of the photovoltaic module while ensuring the electrical connection stability between the solder strip and the grid electrodes.

[0052] Figure 6 for Figure 3 Schematic diagrams of the structure of the welding strip and membrane strip in some embodiments, such as... Figure 6 As shown in this application, the photovoltaic module also includes a coating, which comprises multiple parallel film strips 70. The film strips 70 are disposed on the solar cell 10 and cover a corresponding welding strip 2. The film strips 70 may be made of ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene coelastomer (POE) film, or polyvinyl butyral (PVB) film, etc.

[0053] like Figure 6 As shown, along the thickness direction of the photovoltaic module, the projection of the film strip 70 onto the cell 10 has a dimension L mm along the width direction of the photovoltaic module, where L is between 2.5 mm and 6 mm. Specifically, it can be 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, or other values ​​within the above range, and is not limited here. The width of the film strip 70 is sufficient to cover the width of the solder ribbon 2, which can reduce the misalignment of the solder ribbon on the cell 10 and improve the alignment accuracy of the solder joints on the cell 10. In this application, the film strip 70 is used to pre-fix the solder ribbon 2, which can improve the welding connection stability of the solder ribbon and the solder joints on the cell 10.

[0054] In some embodiments, the light transmittance of the film strip 70 is greater than 85%, preferably greater than 90%, and even more preferably greater than 95%. Increasing the light transmittance of the film strip 70 can reduce its impact on the light-receiving area of ​​the solar cell.

[0055] Continue to refer to Figure 6 The projection of the solder ribbon 2 onto the solar cell 10 along the width direction of the photovoltaic module is D mm, and the L / D ratio is (10~20):1, specifically 10:1, 12:1, 15:1, 18:1, 20:1, or other values ​​within the above range, which are not limited here. Using a film strip 70 to pre-fix the solder ribbon 2 allows for automated flow during production and facilitates subsequent low-temperature lamination processes. When the film strip 70 covers the first conductor of the tin-attached layer, it also reduces the risk of solder buildup, short circuits, and short circuits.

[0056] Figure 7 for Figure 3 A schematic diagram of the structure of the battery cells and solder ribbons in some other embodiments, such as... Figure 7 As shown, a second conductor 23 is provided between the solder joint on the battery cell 10 and the solder strip 2, and at least a portion of the projection of the second conductor 23 overlaps with the projection of the solder strip 2.

[0057] In some embodiments, the second conductor 23 can be solder paste or conductive adhesive, and the solder joints on the battery cell 10 are soldered to the solder ribbon 2 via the second conductor 23. The solder paste also includes organic solvents such as flux, which can increase the soldering strength between the solder ribbon 2 and the battery cell 10 during the low-temperature lamination process. Furthermore, the solder paste can increase the wettability of capillary action, reducing the possibility of cold solder joints between the solder ribbon 2 and the battery cell 10. With the synergistic effect of the membrane strip 70 and the second conductor, it can also better isolate air, prevent oxidation of the solder joints between the solder ribbon and the battery cell, and improve the reliability of the soldering between the solder ribbon 2 and the battery cell 10.

[0058] Figure 8 A flowchart of a method for manufacturing photovoltaic modules in some embodiments, such as... Figure 8 As shown, the manufacturing method of photovoltaic modules includes: S1: Place the solder ribbon 2 on the battery cell 10, and make contact between the solder ribbon 2 and the battery cell 10.

[0059] In this step, the welding strip 2 can be placed automatically by a robotic arm or manually by a worker.

[0060] S2: In the preheated state, the welding strip 2 is fixed by the membrane strip 70, and the welding strip 2 connects the battery cells 10 into a battery string 1.

[0061] The membrane strip 70 is adhesive and is attached to the surface of the battery cell 10. It can pre-fix the welding ribbon 2 so that the welding ribbon 2 will not move freely relative to the battery cell 10.

[0062] S3: An encapsulation layer and a cover plate are provided on both sides of the battery cell 10 to form a laminate; In this step, the encapsulation layer is the first film layer 4 and the second film layer 5, and the cover plate is the first cover plate 3 and the second cover plate 6.

[0063] S4: The component to be laminated is electrically connected to the battery cell 10 via the welding strip 2.

[0064] In this step, a certain pressure and temperature are applied to the laminated component. Under this temperature, the solder ribbon 2 and the solar cell 10 are electrically connected, that is, the solder ribbon 2 is alloyed with the grid line electrodes on the solar cell 10. Achieving alloying between the solder ribbon 2 and the grid line electrodes through the lamination process can also simplify the photovoltaic module manufacturing process, improve the production efficiency of photovoltaic modules, and reduce the production cost of photovoltaic modules.

[0065] In this embodiment, since the lamination temperature is lower than the temperature at which the solder ribbon 2 is directly soldered to the grid line electrodes on the cell 10, the cell 10 can be prevented from warping due to high temperature, reducing the probability of microcracks and fragmentation of the cell 10, which is beneficial to improving the reliability of the produced photovoltaic module.

[0066] At the same time, the pressure applied to the laminate during lamination also helps to suppress the warping of the solar cell 10 and reduce the probability of microcracks and fragmentation of the solar cell 10.

[0067] In some implementations, step S2 specifically includes: The maximum temperature T1 of the preheated battery cell 10 satisfies: 90℃≤T1≤130℃; The membrane strip 70 is attached to one side of the battery cell 10 and covered with the solder strip 2.

[0068] For example, the maximum temperature T1 of the preheated solar cell 10 satisfies: 90℃≤T1≤130℃. For instance, the maximum temperature T1 of the preheated solar cell can specifically be: 90℃, 100℃, 105℃, 108℃, 110℃, 115℃, 120℃, 125℃, 130℃, etc.

[0069] A suitable preheating temperature T1 can melt the tin layer on the surface of the solder ribbon, allowing the film strip to fix the solder ribbon to the surface of the cell 10. Excessively high preheating temperatures can easily cause the film strip to deform, weakening its fixing effect on the solder ribbon. Insufficiently low preheating temperatures are detrimental to fixing the connection between the solder ribbon and the solder joint.

[0070] In some implementations, step S1 further includes: A second conductor 23 is provided on the battery cell 10. The second conductor 23 is solder paste or conductive adhesive. The solder ribbon 2 is placed on the battery cell 10, and the solder ribbon 2 is in contact with the second conductor.

[0071] In this step, the second conductor 23 can be formed on the solar cell 10 by screen printing or inkjet printing. For example, the second conductor 23 can be solder paste or conductive adhesive. The second conductor 23 can improve the reliability of the subsequent connection between the solder ribbon 2 and the solar cell 10. When the solar cell is a high-temperature silver paste solar cell, problems such as weak welding and insufficient alloying may occur during the low-temperature lamination process. In this case, by first setting the second conductor 23 on the solar cell, then setting the solder ribbon 2 on the solar cell and contacting it with the second conductor 23, then fixing it with the film strip 70, and finally welding using the low-temperature lamination process, the low-temperature melting characteristics of the second conductor can be used to achieve a stable weld between the solder ribbon and the solar cell, improving the stability of the photovoltaic module.

[0072] In some implementations, step S2 specifically includes: The maximum temperature T1 of the preheated battery cell satisfies: 90℃≤T1≤130℃, and the second conductor partially melts; The film strip 70 is attached to one side of the battery cell and covers the solder strip 2, at least a portion of which is wrapped by the second conductor.

[0073] Under the preheating effect of step S2, the second conductor 23 partially melts, causing the solder ribbon 2 to sink into and be wrapped by the second conductor 23. The combined action of the second conductor 23 and the film strip 70 effectively fixes the solder ribbon 2, preventing it from deviating from its predetermined position. Further, by controlling the temperature of the preheated cell, the tin layer 22 on the surface of the second conductor 23 or the solder ribbon 2 can become molten, allowing the solder ribbon 2 to be tightly connected to the solder joint through the second conductor 23. Compared to the method of fixing the solder ribbon with a single second conductor, the synergistic effect of the second conductor and the film strip significantly increases the stability of the connection between the solder ribbon and the solder joint on the cell, further reducing solder ribbon misalignment in the low-temperature lamination process. Compared to the single film strip fixing method, adding a second conductor (e.g., solder paste) between the cell solder joint and the solder ribbon makes the conductive connection between the solder joint and the solder ribbon more stable. Therefore, under the combined action of the film strip and the second conductor, the welding strip 2 can be effectively fixed, preventing the welding strip 2 from deviating from the predetermined position, improving the electrical connection stability of the welding strip, and ensuring the output power of the photovoltaic module.

[0074] In some embodiments, when laminating the workpiece, heating the workpiece causes the solder strip 2 to be electrically connected to the second conductor, thereby enabling the solder strip 2 to be alloyed with the gate electrode.

[0075] When laminating the component to be laminated, the encapsulation layer, cover plate and insulation can work together to prevent the molten second conductor from flowing to the adjacent gate electrode, thereby preventing short circuits.

[0076] For example, the highest temperature T2 for heating the part to be laminated satisfies: 140℃≤T2≤160℃. Specifically, the highest temperature T2 for heating the part to be laminated can be: 140℃, 141℃, 142℃, 145℃, 148℃, 150℃, 152℃, 155℃, 158℃, 159℃, 160℃, etc.

[0077] The maximum heating temperature T2 of the component to be laminated should not be too high or too low. If the maximum heating temperature T2 of the component to be laminated is too high (e.g., above 160°C), it may cause damage to the photovoltaic module and increase heat loss, thereby increasing the manufacturing cost of the photovoltaic module. If the maximum heating temperature T2 of the component to be laminated is too low (e.g., below 140°C), it may affect the lamination effect of the component to be laminated and affect the alloying effect between the solder strip 2 and the grid electrode.

[0078] Therefore, the maximum temperature T2 for heating the laminate should be set within a suitable range.

[0079] For example, the heating time t2 of the part to be laminated satisfies: 18min ≤ t2 ≤ 25min. For instance, the heating time t2 of the part to be laminated can specifically be: 18min, 18min30s, 19min, 19min30s, 20min, 20min30s, 21min, 21min30s, 22min, 22min30s, 23min, 23min30s, 24min, 24min30s, 25min, etc.

[0080] The heating time t2 for the component to be laminated should not be too long or too short. If the heating time t2 is too long (e.g., longer than 25 minutes), it will increase the manufacturing time of the photovoltaic module, reduce the production efficiency of the photovoltaic module, increase heat loss, increase the manufacturing cost of the photovoltaic module, and may also damage the photovoltaic module. If the heating time t2 is too short (e.g., shorter than 25 minutes), it will affect the lamination effect of the component to be laminated and affect the alloying effect between the solder strip 2 and the grid electrode.

[0081] Therefore, the heating time t2 of the part to be laminated should be set within an appropriate range.

[0082] In some embodiments, the step of placing the solder ribbon 2 on the battery cell 10 involves: cutting the entire battery cell into at least two sectional battery cells; and placing the solder ribbon on the sectional battery cells.

[0083] The photovoltaic module manufacturing method provided in this application, through a low-temperature lamination welding process, combined with ultra-thin tin-layer solder ribbons or tin-free solder ribbons, can effectively improve the current-carrying capacity of the solder ribbons. While maintaining the overall cross-sectional area of ​​the solder ribbons, it ensures that the light-receiving area of ​​the solar cells remains unaffected, thereby increasing the output power of the photovoltaic module and improving the electrical connection stability between the solder ribbons and the grid electrodes on the solar cells. Tests have shown that, with all other components of the photovoltaic module being identical, for modules with the same diameter thick tin-layer solder ribbons (20µm thickness) and thin tin-layer solder ribbons (5µm), the output power of the module using the thin tin-layer solder ribbons is 2W~5W higher than that using the thick tin-layer solder ribbons.

[0084] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A photovoltaic module, characterized in that, The photovoltaic module includes: A battery string (1) includes multiple battery cells (10), which are arranged side by side along the length of the photovoltaic module; A solder strip (2) is located on one side of the solar cell (10) along the thickness direction of the photovoltaic module, connecting adjacent solar cells (10); and The coating includes multiple parallel film strips (70), which are disposed on the battery cell (1) and cover a corresponding solder strip (2). Wherein, the solder strip (2) is a first conductor (21) with a tin layer or a first conductor without a tin layer; when the solder strip (2) is a first conductor (21) with a tin layer (22), the thickness of the tin layer (22) is less than or equal to 5µm.

2. The photovoltaic module according to claim 1, characterized in that, The solder strip (2) is a first conductor (21) with a tin layer attached. The projection of the solder strip in the cell along the width direction of the photovoltaic module is D mm, where D is 0.15~0.

3. The ratio of the thickness R of the tin layer to D is 1:(30~60).

3. The photovoltaic module according to claim 1, characterized in that, Along the thickness direction of the photovoltaic module, the projection of the film strip (70) in the cell along the width direction of the photovoltaic module is L mm, and the projection of the solder strip (2) in the cell along the width direction of the photovoltaic module is D mm. The ratio of L / D is (10~20):

1.

4. The photovoltaic module according to claim 1, characterized in that, Along the thickness direction of the photovoltaic module, the projection of the film strip (70) in the cell along the width direction of the photovoltaic module has a dimension L of 2.5 mm to 6 mm; the light transmittance of the film strip (70) is greater than 85%.

5. The photovoltaic module according to claim 1, characterized in that, The side of the solar cell facing the solder strip (2) has multiple solder points along the length of the photovoltaic module. A second conductor (23) is provided between the solder points and the solder strip (2). At least part of the projection of the second conductor (23) overlaps with the projection of the solder strip (2).

6. The photovoltaic module according to claim 5, characterized in that, The second conductor is solder paste or conductive adhesive, and the solder strip (2) is soldered to the solder joint by the solder paste or the conductive adhesive.

7. The photovoltaic module according to claim 1, characterized in that, The solder strip (2) is a copper strip with a tin layer or a pure copper strip.

8. A method for manufacturing a photovoltaic module, characterized in that, The photovoltaic module includes a battery string (1), which includes multiple battery cells (10), solder ribbons (2), and a coating. The solder ribbons (2) are located on one side of the battery cells (10) along the thickness direction of the photovoltaic module and connect adjacent battery cells (10). The coating includes multiple parallel film strips (70), which are disposed on the battery cells (1) and cover a corresponding solder ribbon (2). The solder ribbon (2) is either a first conductor (21) with a tin layer (22) or a first conductor without a tin layer. When the solder ribbon (2) is a first conductor (21) with a tin layer, the thickness of the tin layer (22) is less than or equal to 5µm. The manufacturing method of the photovoltaic module includes: The solder strip (2) is placed on the battery cell, and the solder strip (2) is in contact with the battery cell; In the preheated state, the welding strip (2) is fixed by the membrane strip (70), and the welding strip (2) connects the battery cells (10) into a battery string (1). An encapsulation layer and a cover plate are provided on both sides of the battery cell (10) to form a laminate; The component to be laminated is laminated, and the solder strip (2) is electrically connected to the battery cell (10).

9. The method for manufacturing a photovoltaic module according to claim 8, characterized in that, The method for manufacturing the photovoltaic module further includes: A second conductor is disposed on the battery cell (10); The solder strip (2) is placed on the battery cell (10), and the solder strip (2) is in contact with the second conductor (23); The second conductor (23) is solder paste or conductive adhesive.

10. The method for manufacturing a photovoltaic module according to claim 9, characterized in that, The step of fixing the welding strip (2) using the membrane strip (70) in the preheated state includes: The highest temperature T1 of the preheated battery cell satisfies: 90℃≤T1≤130℃, during which the second conductor partially melts; The film strip (70) is attached to one side of the battery cell and covers the solder strip (2), at least a portion of which is wrapped by the second conductor (23).

11. The method for manufacturing a photovoltaic module according to claim 8, characterized in that, The step of fixing the welding strip (2) using the membrane strip (70) in the preheated state includes: The maximum temperature T1 for preheating the solar cells satisfies: 90℃≤T1≤130℃; The membrane strip (70) is attached to one side of the battery cell and covers the solder strip (2).

12. The method for manufacturing a photovoltaic module according to claim 8 or 9, characterized in that, The highest heating temperature T2 of the part to be laminated satisfies: 140℃≤T2≤160℃; And / or, the heating time t2 of the part to be laminated satisfies: 18min≤t2≤25min.

13. The method for manufacturing a photovoltaic module according to claim 8 or 9, characterized in that, The step of setting the solder strip (2) on the battery cell: Cut the whole solar cell into at least two separate solar cells; The solder strip (2) is placed on the sectional battery cell.

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