Photovoltaic module and method for manufacturing the same

Abstract

To provide a photovoltaic module and a method for preparing the photovoltaic module.SOLUTION: A photovoltaic module includes a cell string and a plurality of welding strips. The cell string includes a plurality of battery cells. The battery cells adjacent to each other are connected to each other by the welding strips. Each of the battery cells includes a substrate having a front surface and a back surface facing to each other, a first passivation layer located on the front surface of the substrate, a second passivation layer located on the back surface of the substrate, a plurality of main grids located on a front surface of the second passivation layer. The plurality of main grids is arranged at intervals along a first direction and extend along a second direction. Each of the main grids includes a plurality of pads arranged at intervals along the second direction. Each of the welding strips is in electrical contact with a corresponding main grid, and the welding strip 103 includes a plurality of bending portions arranged continuously along the second direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present application relate to the field of solar cells, and more particularly to photovoltaic modules and methods for manufacturing photovoltaic modules. [Background technology]

[0002] Solar cells have good photoelectric conversion ability, and therefore belong to the center of gravity of the development of clean energy. In full-back contact solar cells, the positive metal electrode and the negative metal electrode are both provided on the back surface of the cell, and the front surface of the cell is not shaded by grid lines, which can eliminate the shading current loss of the metal electrodes and realize the maximum utilization of the incident photons, and therefore have good future prospects. Therefore, photovoltaic modules built with full-back contact solar cells have good application prospects.

[0003] However, in the current design schemes of photovoltaic modules, the battery cells are prone to problems such as crackles and debris that are invisible to the naked eye, and furthermore, there are problems in that the yield of photovoltaic modules is low and the manufacturing costs are too high. Summary of the Invention [Problem to be solved by the invention]

[0004] The embodiments of the present application provide a photovoltaic module and a method for manufacturing a photovoltaic module that at least helps relieve stress when the welding strip and the battery cell make electrical contact, increases the yield of the photovoltaic module, and reduces manufacturing costs. [Means for solving the problem]

[0005] An embodiment of the present invention provides a photovoltaic module, comprising at least one cell string, a plurality of welding strips, at least one sealing layer and at least one cover plate, each of the at least one cell string including a plurality of battery cells, adjacent battery cells being connected via welding strips, the battery cells including a substrate having opposing front and back surfaces, a first passivation layer located on the front surface of the substrate, a second passivation layer located on the back surface of the substrate, and a plurality of main grids located on a surface of the second passivation layer, the plurality of main grids being arranged at intervals in a first direction and extending along a second direction, the main grids being spaced apart in the second direction, and the plurality of main grids being spaced apart in the second direction. the welding strip includes a plurality of pads arranged in a continuous manner in the second direction, each of the welding strips being in electrical contact with a corresponding one of the main grids, the welding strips including a plurality of bent portions arranged continuously in the second direction, and in the second direction, an orthogonal projection of a center line of each of the welding strips on a rear surface of the battery cell is superimposed on a center line of the corresponding main grid and / or an orthogonal projection of a center line of each of the pads on the corresponding main grid on a rear surface of the battery cell, the at least one sealing layer is disposed on a surface of the at least one cell string, and the at least one cover plate is disposed on a surface of the at least one sealing layer away from the at least one cell string, and then laminated and molded.

[0006] In addition, in the second direction, the bending directions of adjacent bending portions are the same or opposite.

[0007] The shape of the bent portion includes a circular arc shape, a square shape, or a broken line shape.

[0008] Additionally, each of the pads is in electrical contact with two adjacent folded portions of the welding strip.

[0009] Further, the bending portion includes a first bending portion that is in electrical contact with a corresponding pad and a second bending portion that is not in electrical contact with any of the pads, and in a third direction, a size of the first bending portion is larger than a size of the second bending portion, and the third direction is perpendicular to the bending direction of the bending portion.

[0010] In addition, in a fourth direction, a distance between the main grid and a bending apex of the bending portion that is away from the main grid is 0.1 mm to 0.3 mm, and the fourth direction is perpendicular to the second direction.

[0011] The ratio of the length of the bent portion in the bending direction to the length of the bent portion in the second direction is 1.05 to 1.25.

[0012] Further, the plurality of bent portions have the same length in the second direction.

[0013] Additionally, the plane on which each of the welding strips lies is parallel to the rear surface of the battery cell.

[0014] Using each pad in the main grid as a partition, the main grid connection lines are divided into a plurality of solder resist areas arranged in the second direction, and the solder resist areas are solder resist treated using a solder resist ink by a method such as printing or adhesive application.

[0015] During the solder resist process, each solder resist area may be completely covered with solder resist ink, or the solder resist area may be divided into multiple solder resist sub-areas, each of which is completely covered, where the position of each solder resist sub-area corresponds to the position of an isotropic sub-grid that is opposite in polarity to the main grid.

[0016] During the solder resist processing, the size of the solder resist ink should satisfy the following: thickness is 15 μm or more higher than the height of the solder resist area or solder resist sub-area, and width is 50 μm or more wider than the width of the solder resist area or solder resist sub-area.

[0017] The solder resist ink is an insulating adhesive.

[0018] Accordingly, an embodiment of the present invention further provides a method for manufacturing a photovoltaic module, comprising: providing a plurality of battery cells, the battery cells including a substrate having a front surface and a back surface opposite to each other, a first passivation layer disposed on the front surface of the substrate, a second passivation layer disposed on the back surface of the substrate, and a plurality of main grids disposed on a surface of the second passivation layer, the plurality of main grids being arranged at intervals in a first direction and extending along a second direction, the main grids including a plurality of pads arranged at intervals in the second direction; providing a plurality of welding strips, and continuously shaping the welding strips using a shaping process to form folds continuously arranged in the second direction; and forming a plurality of welding strips in the second direction. the method includes aligning an orthogonal projection of a center line of a lip on a rear surface of the battery cell with an orthogonal projection of a center line of a corresponding main grid and / or a center line of each of the pads on the corresponding main grid on a rear surface of the battery cell, and electrically contacting each of the welding strips to the corresponding main grid using an electrical connection process to form a cell string in which adjacent battery cells are connected via the welding strips; providing at least one sealing layer and at least one cover plate, disposing the at least one sealing layer on a surface of the at least one cell string, and disposing the at least one cover plate on a surface of the at least one sealing layer away from the at least one cell string, and then stacking and molding the same.

[0019] The shaping step includes bending, folding, forging, or pressing. Effect of the Invention

[0020] The technical solutions provided in the embodiments of the present application have at least the following advantages: In the technical proposal of the photovoltaic module provided in the embodiments of the present application, the front surface of the substrate is a suede surface formed by a first passivation layer, and the back surface of the substrate is a second passivation layer including a plurality of main grids arranged at intervals in a first direction on the surface and extending in a second direction. After arranging a plurality of full back-contact type battery cells in an orderly manner, each welding strip consisting of a plurality of bent portions arranged continuously in the second direction is electrically contacted to a corresponding main grid to form a cell string by connecting adjacent battery cells with the welding strip, and the adjacent battery cells are connected with the welding strip consisting of a plurality of bent portions arranged continuously, and the bent portions are used as buffer portions to fully release stress in the process of connecting the battery cells with the welding strip, thereby avoiding warping of the battery cells, and improving the reliability and yield of the cell string. The main grid includes a plurality of pads arranged at intervals in the second direction, and in the process of connecting adjacent battery cells with the welding strips, first, in the second direction, align the orthogonal projection of the center line of each welding strip on the rear surface of the battery cell with the orthogonal projection of the center line of the corresponding main grid and / or the center line of each pad on the corresponding main grid on the rear surface of the battery cell to overlap the orthogonal projection of the center line of the welding strip with the orthogonal projection of the center line of the main grid and / or the center line of each pad on the main grid, and then electrically contact the welding strips to the corresponding main grid to complete the fabrication of the cell string, and overlap the orthogonal projection of the center line of the welding strip on the rear surface of the battery cell with the orthogonal projection of the center line of the main grid and / or the center line of each pad on the main grid on the rear surface of the battery cell to ensure the aesthetics and connection effect when connecting the battery cells using the welding strips, and avoid an increase in contact resistance caused by the welding strips being deviated from the main grid area, which would affect the efficiency of the cell string. [Brief description of the drawings]

[0021] One or more embodiments are illustratively illustrated in corresponding figures in the accompanying drawings, which illustrations are not intended to be limiting of the embodiments, and unless otherwise specified, the figures in the accompanying drawings do not form a limiting scale. [Figure 1] FIG. 1 is a diagram showing a configuration of a cell string according to an embodiment of the present application. [Diagram 2] FIG. 2 is a diagram showing a configuration of grid lines of a battery cell according to one embodiment of the present application. [Diagram 3] FIG. 3 is a diagram showing a configuration of a welding strip according to an embodiment of the present application. [Figure 4] FIG. 4 is a diagram showing a configuration of a battery cell according to an embodiment of the present application. [Diagram 5] FIG. 5 is a schematic diagram of a welding strip having different bent portions according to an embodiment of the present invention. [Figure 6] FIG. 6 is another schematic diagram of different bent portions forming a plurality of types of welding strips according to an embodiment of the present application. [Figure 7] FIG. 7 is a schematic diagram of electrical contact between a welding strip and a pad according to one embodiment of the present application. [Figure 8] FIG. 8 is a diagram showing a main grid including a solder resist region according to an embodiment of the present application. [Figure 9] FIG. 9 is another diagram of electrical contact between a welding strip and a pad according to one embodiment of the present application. [Figure 10] FIG. 10 is another diagram of electrical contact between a welding strip and a pad according to one embodiment of the present disclosure. [Figure 11] FIG. 11 is a flow chart of a method for manufacturing a photovoltaic module according to another embodiment of the present application. [Figure 12] FIG. 12 is a diagram showing a configuration of a photovoltaic module according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] As can be seen from the background art, the photovoltaic modules of the prior art are prone to problems such as crackles and debris that are invisible to the naked eye in the battery cells, and furthermore, the yield of the photovoltaic modules is low, and the manufacturing cost is too high.

[0023] In one embodiment of the present application, a photovoltaic module is provided, in which, when constructing a cell string with a plurality of full back-contact type battery cells, after the battery cells are arranged in an orderly manner, adjacent battery cells are connected using a welding strip composed of a plurality of bent portions arranged continuously in a second direction, and the bent portions are used as buffer portions to fully release stress in the process of connecting the battery cells with the welding strip, to avoid warping of the battery cells, and to improve the reliability and yield of the cell string; in the process of connecting adjacent battery cells with the welding strip, in the second direction, first, the orthogonal projection of the center line of each welding strip on the rear surface of the battery cell is projected on the rear surface of the battery cell by the center line of the corresponding main grid and / or the center line of each pad on the corresponding main grid. By aligning the welding strip with the orthogonal projection on the rear surface of the battery cell, the orthogonal projection of the center line of the welding strip is overlapped with the orthogonal projection of the center line of the main grid and / or the orthogonal projection of the center lines of each pad on the main grid, and the welding strip is electrically contacted to the corresponding main grid to complete the fabrication of the cell string. By overlapping the orthogonal projection of the center line of the welding strip with the orthogonal projection of the center line of the main grid and / or the orthogonal projection of the center line of each pad on the main grid on the rear surface of the battery cell, it is possible to ensure the aesthetics and connection effect when connecting the battery cells using the welding strip, and to avoid the welding strip being out of the main grid area, which would result in an increase in contact resistance and affect the efficiency of the cell string.

[0024] Hereinafter, each embodiment of the present application will be described in detail with reference to the drawings. However, as will be understood by those skilled in the art, in order to allow the reader to better understand the present application, many technical details are proposed in each embodiment of the present application, but even without these technical details, the technical solution claimed for protection by the present application can be realized by various changes and modifications based on the following embodiments.

[0025] As shown in Figures 1 to 4, Figure 1 is a schematic diagram showing the configuration of the back surface of a cell string 101, Figure 2 is a diagram showing the configuration of grid lines on the back surface of a battery cell 102, Figure 3 is a diagram showing the configuration after enlarging a welding strip 103, and Figure 4 is a diagram showing the battery configuration of the battery cell 102. The photovoltaic module includes a cell string 101, a plurality of welding strips 103, at least one sealing layer 120 and at least one cover plate 130, each of the at least one cell string 101 includes a plurality of battery cells 102, adjacent battery cells 102 are connected via the welding strips 103, the battery cells 102 include a substrate 1021 having a front surface and a back surface facing each other, a first passivation layer 1022 located on the front surface of the substrate 1021, a second passivation layer 1023 located on the back surface of the substrate 1021, and a plurality of main grids 1024 located on the surface of the second passivation layer 1023, the plurality of main grids 1024 are arranged at intervals in a first direction and extend along a second direction, and adjacent main grids 1024 are connected to each other via the welding strips 103. The sub-grids 1024 are connected to the sub-grids 1024 of opposite polarity and the same polarity, the main grids 1024 include a plurality of pads 1025 arranged at intervals in the second direction, each welding strip 103 is in electrical contact with its corresponding main grid 1024, the welding strips 103 include a plurality of folds arranged successively in the second direction, and in the second direction, an orthogonal projection of a centerline of each welding strip 103 on a rear surface of the battery cell 102 is superimposed on an orthogonal projection of a centerline of the corresponding main grid 1024 and / or a centerline of each pad 1025 on the corresponding main grid 1024 on a rear surface of the battery cell 102, where the X direction is the first direction and the Y direction is the second direction. At least one sealing layer 120 is disposed on a surface of the at least one cell string 101, and at least one cover plate 130 is disposed on a surface of the at least one sealing layer 120 away from the at least one cell string 101, and then laminated and molded.

[0026] As can be understood, the above embodiment shows one example in which the welding strip 103 is electrically contacted to the main grid 1024. However, in a specific application, in view of the deviations that may occur in each pad 1025 during the manufacture of the main grid 1024 and the difficulty of achieving perfect alignment of the centerlines, when the centerline of the welding strip 103 is aligned with the centerline of the main grid 1024 and / or the centerlines of each pad 1025 on the main grid 1024 are aligned with each other, it is acceptable for there to be a certain degree of overlap deviation between the centerlines, for example, in the direction perpendicular to the second direction, there is a 10% or 20% deviation between the centerlines, that is, the overlapping area of ​​the centerlines occupies 90% or 80% of the total area of ​​the centerlines, so as to ensure the effect of electrical contact as much as possible while reducing the application difficulty of the invention.

[0027] In the process of constructing the cell string 101 using back-contact type battery cells in which multiple main grids 1024 are all provided on the second passivation layer 1023 on the back surface of the battery cells 102, adjacent battery cells 102 are connected using a welding strip 103 consisting of multiple bent portions arranged continuously in the second direction. When each welding strip 103 is welded to a corresponding main grid 1024 to achieve electrical contact therebetween, the multiple continuous bent portions of the welding strip 103 are used as multiple buffer portions to release welding stress caused by the welding strip 103 and the battery cells 102 having different thermal expansion coefficients and thus having different contraction amounts after welding, thereby ensuring the welding effect when the welding strip 103 is used to connect adjacent battery cells 102, preventing the battery cells 102 from warping, and improving the yield of the cell string 101. In the process of electrically contacting the welding strips 103 to the corresponding main grids 1024, in the second direction, the orthogonal projection of the center line of each welding strip 103 on the rear surface of the battery cell 102 is aligned with the orthogonal projection of the center line of the main grid 1024 corresponding to the welding strip 103 and / or the center line of each pad 1025 on the main grid 1024 corresponding to the welding strip 103 on the rear surface of the battery cell 102.After the orthogonal projection of the center line of the welding strip 103 is overlapped with the center line of the main grid 1024 corresponding to the welding strip 103 and / or the center lines of each pad 1025 on the main grid 1024 corresponding to the welding strip 103, each welding strip 103 is electrically contacted to its corresponding main grid 1024 through an electrical connection process, for example, welding, to connect adjacent battery cells 102 to form a cell string 101; the center line of the welding strip 103 is aligned with the center line of the main grid 1024 or the center lines of each pad 1025 on the main grid 1024 to ensure the aesthetics and connection effect when connecting the battery cells 102 using the welding strip 103, and avoid the increase in contact resistance between the welding strip 103 and the main grid 1024 caused by the welding strip 103 being offset from the area on the main grid 1024, which would affect the efficiency of the cell string 101.

[0028] The substrate 1021 is for receiving incident light to generate photo-generated carriers, and in some embodiments, the substrate 1021 may be a silicon substrate, and the material of the silicon substrate may include at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In other embodiments, the material of the substrate 1021 may be silicon carbide, an organic material, or a multi-element compound. The multi-element compound may include, but is not limited to, materials such as perovskite, gallium arsenide, cadmium telluride, and copper indium selenide.

[0029] In addition, the first direction and the second direction may be perpendicular to each other, or may have an included angle smaller than 90 degrees, such as 60 degrees, 45 degrees, 30 degrees, etc., as long as the first direction and the second direction are not the same direction. In this embodiment, for ease of explanation and understanding, the first direction and the second direction are described as being perpendicular to each other, but in a specific application, the setting of the included angle between the first direction and the second direction can be adjusted according to actual needs and application scenes, and this embodiment does not limit thereto.

[0030] In some embodiments, the shape of the bent portion includes a circular arc, a square, or a broken line. As shown in Figures 2 and 5, Figure 5 shows a diagram illustrating a configuration of a plurality of welding strips 103 including a circular arc bent portion 501, a square bent portion 502, and a broken line bent portion 503 in sequence.

[0031] In the process of shaping the welding strip 103, the shape of the bent portion formed by shaping can be set according to the situation. For example, when the thermal expansion coefficients of the battery cells 102 and the welding strip 103 are significantly different, in order to maximize the stress release capacity of each bent portion of the welding strip 103, when the degree of bending is the same, that is, when the distance between the bent apex farthest from the center line of the welding strip 103 in the second direction and the center line of the bent portion is the same, the shape of the bent portion can be selected to be set as an arc shape or a square shape, so as to maximize the ratio between the length of the bent portion in the bending direction and the length of the bent portion in the first direction, thereby improving the stress release capacity of the bent portion. When the thermal expansion coefficients of the battery cells 102 and the welding strip 103 differ slightly, if other conditions such as the degree of bending are consistent, it is possible to select to set the shape of the bending portion to a broken line such as a triangle, a rectangle, or a trapezoid in order to reduce the area of ​​the welding strip 103 covering the rear surface of the battery cells 102 as much as possible, thereby avoiding a short circuit caused by contact between the welding strip 103 and the sub-grid on the rear surface of the battery cells 102 and ensuring the degree of insulation of the cell string 101. When other conditions are consistent and both the stress release capability of the welding strip 103 and the reduction in the area of ​​the welding strip 103 covering the rear surface of the battery cells 102 are to be achieved, the shape of the bending portion can be set to an arc shape in which the area of ​​the rear surface of the battery cells 102 that should be occupied by the welding strip 103 is small, and when it is necessary to increase the stress release capability of the welding strip 103 as much as possible, the shape of the bending portion can be set to a square shape in which the area of ​​the rear surface of the battery cells 102 that should be occupied by the welding strip 103 is large. According to application scenarios and needs, a suitable shape of the bent portion is selected from a number of shapes to shape the welding strip 103, so as to ensure that the welding strip 103 can be adapted to different application scenarios and needs.

[0032] As can be understood, the arc shape among the shapes of the bent portions may be an arc, an elliptical arc, or an irregular arc shape composed of a plurality of camber lines. The broken line shape may be a figure composed of a plurality of broken lines such as a triangle, a rectangle, or a trapezoid. The "Z" shape may be a smooth figure composed of a plurality of arc-shaped lines, or a figure composed of a combination of a plurality of broken lines and a plurality of arc-shaped lines, or a figure similar to a normal distribution curve. In this embodiment, there is no limitation on the specific structure of the bent portions with different shapes.

[0033] In some embodiments, in the second direction, the bending directions of adjacent bent portions are the same or opposite. As shown in FIG. 6, FIG. 6 sequentially shows diagrams showing the configurations of a plurality of welding strips 103 in which, in the second direction, the bending directions of adjacent arc-shaped bent portions are the same or opposite, and the bending directions of adjacent "Z" - shaped bent portions are the same or opposite.

[0034] In the process of shaping the welding strip 103, the relationship between the bending directions of the adjacent bending parts can be adjusted as necessary. In order to minimize the covering area of ​​the welding strip 103 on the rear surface of the battery cell 102 as long as other conditions, such as the bending degree and the width of the welding strip 103 itself, are consistent, in the process of constructing the welding strip 103, two adjacent bending parts can be bent toward the same bending direction, so as to reduce the covering area of ​​the welding strip 103 on the rear surface of the battery cell 102, and reduce the sub-surface area of ​​the welding strip 103 and the rear surface of the battery cell 102. In order to minimize contact with the grid, avoid the occurrence of short circuit in the battery cell 102, and provide the welding strip 103 with a good stress relief effect, in the process of constructing the welding strip 103, two adjacent bent portions can be bent in opposite bending directions, and the bent portions in the welding strip 103 are alternately arranged in different bending directions, so that the bending portions in the welding strip 103 can have a good stress relief effect in the direction in which there are more bent portions, and the overall shape of the welding strip 103 is as smooth and beautiful as possible. Therefore, the bending directions of adjacent bent portions in the welding strip 103 can be set to be the same or opposite to each other to meet different application scenarios and needs.

[0035] It should be understood that, for ease of understanding, this embodiment is described as an example in which the relationship between the bending directions of each adjacent folding portion is consistent, but in a specific application, in the second direction, the relationship between the bending directions of each adjacent folding portion in the welding strip 103 may be consistent, that is, the bending directions of all adjacent folding portions are the same or opposite to each other, and the relationship between the bending directions of each adjacent folding portion may not be consistent, that is, the bending directions of some adjacent folding portions are the same and the bending directions of some adjacent folding portions are opposite to each other, and this embodiment is not limited thereto.

[0036] In some embodiments, each of the pads 1025 is in electrical contact with two adjacent folds of the welding strip 103. As shown in Figures 2 and 7, the welding strip 103 is configured with arcuate folds 501 in which the adjacent folds are bent in opposite directions, and each of the pads 1025 is in contact with two adjacent folds of the welding strip 103, and the intersection lines of the two arcuate folds 501 overlap the center line of the pad 1025 in the first direction. That is, before electrically contacting the welding strip 103 to the main grid 1024, in the second direction, the orthogonal projection of the center line of the welding strip 103 on the back surface of the battery cell 102 can be aligned with the center line of the main grid 1024 and / or the orthogonal projection of the center line of each pad 1025 on the main grid 1024 on the back surface of the battery cell 102, and then, in a direction perpendicular to the second direction, the intersection line between adjacent folded portions connected to the pads 1025 can be aligned with the center lines of the pads 1025, and then in the electrical connection process, the pads 1025 are electrically contacted to the two adjacent folded portions to complete the electrical contact between the welding strip 103 and the corresponding main grid 1024. Since the pad 1025 is in electrical contact with both of the two adjacent folded portions, when the welding strip 103 and the battery cell 102 experience different amounts of shrinkage due to different thermal expansion coefficients, the pad 1025 can directly utilize the two adjacent folded portions that are in electrical contact with it to relieve the stress caused by the different amounts of shrinkage of the welding strip 103 and the battery cell 102, thereby improving the stress relief ability and effect.

[0037] As can be understood, the above embodiment only provides one configuration diagram of the pad 1025 electrically contacting the welding strip 103, but in the process of electrically contacting the pad 1025 and two adjacent folded portions of the welding strip 103, taking into consideration factors such as the difficulty of realization and mechanical error, in the direction perpendicular to the second direction, the intersection line between the folded portions can not only be aligned with the center line of the pad 1025, but also the positional relationship between the intersection line and the center line of the pad 1025 can be set to be incompletely overlapped or separated, for example, the overlapping area of ​​the center line of the pad 1025 and the intersection line of the adjacent folded portions occupies 90%, 80%, or 50% of the total area, or in the second direction, the distance between the intersection line of the adjacent folded portions and the center line is 10%, 20%, or 45%, etc. of the maximum length of the pad 1025. In order to ensure the stress relief effect, the difficulty of electrically contacting the welding strip 103 with the pad 1025 is reduced. In this embodiment, when the pad 1025 electrically contacts the two adjacent bends in the welding strip 103, there is no restriction on the specific positional relationship between the intersection line of the bends and the center line of the pad 1025 in the second direction.

[0038] In addition, as shown in Figures 2 and 8, the main grid 1024 includes a main grid connection line 801 and a pad 1025. In order to prevent the sub-grid on the back surface of the battery cell 102 from electrically contacting the main grid 1024 of the opposite polarity to itself, or the sub-grid from electrically contacting the welding strip 103 corresponding to the main grid 1024 of the opposite polarity to itself, before connecting the battery cells 102, each main grid 1024 on the back surface of each battery cell 102 can be further treated with solder resist in advance. Using each pad 1025 of the main grid 1024 as a partition, the main grid connection line 801 is divided into a plurality of solder resist areas 802 arranged in the second direction, and then the solder resist areas 802 are solder resist treated by a method such as printing or adhesive application using a solder resist ink, for example an insulating adhesive. In the process of solder resist treatment, each solder resist area 802 may be completely covered by the solder resist ink, or the solder resist area 802 may be divided into a plurality of solder resist sub-areas 803 and each solder resist sub-area 803 may be completely covered, where the position of each solder resist sub-area 803 corresponds to the position of the opposite polarity sub-grid of the main grid 1024 to avoid contact between the welding strip 103 and the main grid 1024 and the sub-grid of the opposite polarity of the main grid 1024. During the solder resist processing, the size of the solder resist ink should satisfy the following requirements: thickness is at least 15 μm higher than the height of the solder resist area 802 or the solder resist sub-area 803, and width is at least 50 μm wider than the width of the solder resist area 802 or the solder resist sub-area 803; this embodiment does not impose any restrictions on the specific size of the solder resist ink.

[0039] Here, the third direction is the Z direction, as shown in Figures 2 and 9. In some embodiments, the folding portion includes a first folding portion 901 electrically contacting a corresponding pad 1025 and a second folding portion 902 not electrically contacting any pad 1025, the size of the first folding portion 901 is larger than the size of the second folding portion 902 in the third direction, and the third direction is perpendicular to the folding direction of the folding portion.

[0040] The main function of the welding strip 103 is to connect adjacent battery cells 102 and transport the current collected in the main grid 1024 that is in electrical contact with the welding strip 103 to the module end that is connected to the cell string 101, and the current carrying capacity of the welding strip 103 is related to its own resistance and the contact resistance between the welding strip 103 and the main grid 1024. When the welding strip 103 is in electrical contact with the main grid 1024 through each pad 1025 on the main grid 1024, the contact resistance between the welding strip 103 and the main grid 1024 is related to the contact area between the welding strip 103 and the pad 1025.

[0041] Therefore, in the process of shaping the welding strip 103 to form the bent portions, after forming the welding strip 103 with a plurality of bent portions arranged continuously in the second direction, the welding strip 103 is aligned with the corresponding main grid 1024 to identify the first bent portion 901 in the welding strip 103 that is in electrical contact with the pad 1025 and the second bent portion 902 that is not in electrical contact with the pad 1025. In the third direction, the sizes of the first bent portion 901 and the second bent portion 902 refer to the widths of both of them in the third direction, respectively, and therefore the third direction is a direction parallel to the back surface of the battery cell 102 and perpendicular to the second direction. When the original width of the welding strip 103 in the direction perpendicular to the stretching direction before shaping is small, the first bent portion 901 is pulled along a third direction perpendicular to the bending direction, so that the size of the first bent portion 901 of the welding strip 103 becomes larger than the size of the second bent portion 902 in the third direction, and when the original width of the welding strip 103 in the direction perpendicular to the stretching direction before shaping is large, the second bent portion 902 is compressed in the third direction perpendicular to the bending direction, so that the size of the first bent portion 901 of the welding strip 103 becomes larger than the size of the second bent portion 902 in the third direction. The first bent portion 901 or the second bent portion 902 in the welding strip 103 is secondarily shaped so that the size of the first bent portion 901 becomes larger than the size of the second bent portion 902 in a third direction perpendicular to the bending direction, and then the adjacent first bent portion 901 is connected to the corresponding pad 1025 to complete the electrical contact between the welding strip 103 and the corresponding main grid 1024.

[0042] In a third direction perpendicular to the bending direction, the size of the first bent portion 901 that electrically contacts the pad 1025 of the welding strip 103 is set larger, thereby increasing the electrical contact area between the welding strip 103 and the pad 1025, reducing the contact resistance between the two, improving the current transport capacity of the welding strip 103, and ensuring the operating efficiency of the cell string 101.

[0043] 2 and 10, here the fourth direction is direction F. In some embodiments, in the fourth direction, the distance between the folding vertex 1001 away from the main grid 1024 of the folding portion and the main grid 1024 is 0.1 mm to 0.3 mm, and the fourth direction is perpendicular to the second direction.

[0044] 10, the welding strip 103 is composed of arc-shaped bent portions, in which adjacent bent portions are bent in opposite directions. In the fourth direction, the distance between the bent apex 1001 of the bent portion and the main grid 1024 is the minimum distance from the orthogonal projection of the bent apex 1001 on the rear surface of the battery cell 102 to the center line of the orthogonal projection of the main grid 1024 on the rear surface of the battery cell 102, that is, the fourth direction is parallel to the rear surface of the battery cell 102 and perpendicular to the second direction. In the fourth direction, if the distance between the bend apex 1001 and the main grid 1024 is too small, the degree of bending of the bend is low, which reduces the ability of the bend to release the stress generated between the welding strip 103 and the battery cell 102. Furthermore, the stress is not effectively released, which may cause the battery cell 102 to warp or crack, which may affect the yield and production cost of the cell string 101. If the distance between the bend apex 1001 and the main grid 1024 is too large, the degree of bending of the bend is low, which reduces the ability of the bend to release the stress generated between the welding strip 103 and the battery cell 102. When the bending degree is too high, the bending portion has excessive ability to release the stress generated between the welding strip 103 and the battery cell 102, and at the same time, the overall length of the welding strip 103 is too large, which reduces the current carrying ability of the welding strip 103; when the bending degree is too high, the welding strip 103 is easily brought into electrical contact with the opposite polarity sub-grid of the main grid 1024 corresponding to the welding strip 103 itself on the back surface of the battery cell 102, which affects the insulation of the battery cell 102.

[0045] Therefore, in the fourth direction, the distance between the bend apex 1001 of the bent portion of the welding strip 103, which is away from the main grid 1024, and the main grid 1024 can be set to 0.1 mm to 0.3 mm, for example, 0.15 mm, 0.2 mm, or 0.25 mm, etc., so that the bent portion can effectively release the stress generated between the welding strip 103 and the battery cells 102 to increase the yield of the cell strings 101, while at the same time ensuring the current transport capacity of the welding strip 103 and the insulation of the battery cells 102.

[0046] In some embodiments, the ratio of the length of the bent portion in the bending direction to the length of the bent portion in the second direction is 1.05 to 1.25. The main function of the bent portion is to act as a buffer to release stress generated between the welding strip 103 and the battery cell 102, and the stress release ability of the bent portion is not only related to the bending degree of the bent portion itself, but also to the ratio of the length of the bent portion in the bending direction to the length of the bent portion in the extension direction, i.e., the ratio of the length of the bent portion in the bending direction to the length of the bent portion in the second direction. Under other conditions, if the ratio of the length of the bent portion in the bending direction to the length of the bent portion in the second direction is too small, the magnitude of the releasable stress of the bent portion will be quite limited, restricting the ability of the bent portion to release the stress generated between the welding strip 103 and the battery cells 102, and the stress release effect will be limited, and the battery cells 102 will still be prone to warping or cracking, affecting the yield and production cost of the cell string 101; if the ratio of the length of the bent portion in the bending direction to the length of the bent portion in the second direction is too large, the releasable stress of the bent portion will be large, and the ability of the bent portion to release the stress generated between the welding strip 103 and the battery cells 102 will be excessive, and the overall length of the welding strip 103 will be too large, reducing the current carrying capacity of the welding strip 103 and increasing the production cost of the cell string 101.

[0047] Therefore, the ratio of the length of the bending portion of the welding strip 103 in the bending direction to the length of the bending portion in the second direction can be set to 1.05 to 1.25, for example, 1.10, 1.15, or 1.20, so that the bending portion can effectively release the stress generated between the welding strip 103 and the battery cells 102 to increase the yield of the cell string 101, while at the same time ensuring the current transport capacity of the welding strip 103 and avoiding the problem of the production cost of the cell string 101 being too high.

[0048] In some embodiments, the lengths of the plurality of bent portions in the second direction are the same. As described in the above embodiments, the main function of the bent portions is to act as buffers to release stress generated between the welding strip 103 and the battery cells 102. Since the materials used in manufacturing the main grids 1024 of the battery cells 102 are generally the same, and the magnitude of stress to be released at each contact position when the welding strip 103 is electrically contacted with the main grids 1024 is also basically the same, it is possible to set the lengths of the bent portions in the second direction to the same length, which ensures the stress release effect and aesthetics, while facilitating the shaping and manufacturing of the welding strip 103 through the regular distribution and similar specifications of the bent portions, thereby reducing the difficulty of shaping the welding strip 103 and improving the efficiency of shaping and production.

[0049] As will be understood, when the battery cell 102 is provided with a special structure or requirements, the length of the bent portion of a certain part in the second direction can be set independently according to the needs of the application scenario; in addition, taking into consideration the production efficiency and the difficulty and accuracy of actual production, the length of each bent portion in the second direction may have a certain deviation from the preset standard length, for example, a deviation of 5%, 10%, 15%, etc. between the actual length and the standard length, and this embodiment does not place any limitation thereon.

[0050] In some embodiments, the plane on which each welding strip 103 exists is parallel to the rear surface of the battery cell 102. In the process of shaping the welding strip 103, a number of folds are formed in the plane parallel to the rear surface of the battery cell 102, which are arranged continuously along the stretching direction; and in the process of using the welding strip 103 to connect the battery cells 102, the plane on which each fold of the welding strip 103 exists is arranged parallel to the rear surface of the battery cell 102, and the welding strip 103 is electrically connected to the main grid 1024 by an electrical connection technique. By arranging the plane on which the welding strip 103 exists parallel to the rear surface of the battery cell 102, the welding strip 103 is prevented from having a convex or concave portion in a direction perpendicular to the rear surface of the battery cell 102, thereby avoiding the problem of the maximum height of the cell string 101 increasing due to the presence of a convex portion, reducing the storage volume required for the cell string 101, and further reducing the volume of the photovoltaic module. At the same time, the problem of the welding strip 103 easily damaging the battery cell 102 and the main grid 1024 when a concave portion exists is avoided, and the integrity of the grid lines of the battery cell 102 and the photoelectric conversion efficiency of the entire battery cell 102 can be ensured.

[0051] Corresponding to the above, in another embodiment of the present application, a photovoltaic module manufacturing method is further provided, which can form the photovoltaic module according to the previous application embodiment, and the specific flow of the manufacturing method, as shown in FIG. 11, includes:

[0052] As shown in Figures 2 and 4, a plurality of battery cells 102 is provided.

[0053] The battery cell 102 includes a substrate 1021 having opposing front and back surfaces, a first passivation layer 1022 located on the front surface of the substrate 1021, a second passivation layer 1023 located on the back surface of the substrate 1021, and a plurality of main grids 1024 located on the surface of the second passivation layer 1023, the plurality of main grids 1024 being arranged at intervals in a first direction and extending along a second direction, and the main grid 1024 includes a plurality of pads 1025 arranged at intervals in the second direction.

[0054] As shown in Fig. 3, a plurality of welding strips 103 are provided, and the welding strips 103 are successively shaped using a shaping process to form the bent portions that are successively arranged in the second direction. In the process of shaping the welding strips 103 to form the bent portions, since the successive shaping method is used, there is no need to consider issues such as how to space the bent portions and the size of the gap between adjacent bent portions, so that the shaping is easier and the yield of the welding strips 103 after shaping is higher, and since the welding strips 103 are composed of the bent portions that are successively arranged, the appearance of the welding strips 103 is smoother and more beautiful.

[0055] In some embodiments, the shaping process includes bending, folding, forging, or pressing.

[0056] As shown in FIGS. 1 to 3, the positions of the welding strips 103 are specified and the cell strings 101 are formed in an electrical connection process.

[0057] In the second direction, the orthogonal projection of the centerline of each welding strip 103 on the back surface of the battery cell 102 is aligned with the orthogonal projection of the centerline of the corresponding main grid 1024 and / or the centerline of each pad 1025 on the corresponding main grid 1024 on the back surface of the battery cell 102, and an electrical connection process is used to electrically contact each welding strip 103 to the corresponding main grid 1024 to form a cell string 101 in which adjacent battery cells 102 are connected via the welding strips 103.

[0058] As shown in FIG. 12, at least one sealing layer 120 and at least one cover plate 130 are provided, the at least one sealing layer 120 is disposed on a surface of the at least one cell string 101, and the at least one cover plate 130 is disposed on a surface of the at least one sealing layer 120 away from the at least one cell string 101, and then laminated and molded.

[0059] The finally formed photovoltaic module may include a cell string 101 formed by a plurality of battery cells 102, an encapsulation layer 120 for covering the surfaces of the battery cells 102, and a cover plate 130 for covering the surfaces of the encapsulation layer 120 remote from the battery cells 102, where the cell string 101 is a cell string 101 according to a plurality of the above embodiments, and the plurality of battery cells 102 are electrically connected in series and / or parallel.

[0060] Specifically, in some embodiments, the battery cells 102 may be electrically connected to each other by a welding strip 103. The sealing layer 120 covers the front and back surfaces of the battery cells 102, and specifically, the sealing layer 120 may be an organic sealing film, such as an ethylene-vinyl acetate copolymer (EVA) film, a polyolefin elastomer (POE) film, or a polyethylene terephthalate (PET) film. In some embodiments, the cover plate 130 may be a cover plate 130 having a light transmission function, such as a glass cover plate, a plastic cover plate, or the like. Specifically, the surface of the cover plate 130 facing the sealing layer 120 may be an uneven surface, which can improve the utilization rate of the incident light.

[0061] Although the present application has been disclosed as above in the examples, it does not limit the scope of the claims, and a person skilled in the art may make some possible variations and modifications without departing from the idea of ​​the present application, so the protection scope of the present application should be in accordance with the scope defined by the claims of the present application.

[0062] Those skilled in the art will understand that the above embodiments are specific examples for implementing the present application, but various changes in form and details are possible in practice without departing from the spirit and scope of the present application. Since any person skilled in the art can make changes and modifications without departing from the spirit and scope of the present application, the scope of protection of the present application should be based on the scope limited by the claims.

Claims

1. A photovoltaic module, comprising: at least one cell string, a plurality of welding strips, at least one sealing layer, and at least one cover plate; Each of the at least one cell string includes a plurality of battery cells, and adjacent battery cells are connected via the welding strips; The battery cell includes a substrate having opposing front and back surfaces, a first passivation layer located on the front surface of the substrate, a second passivation layer located on the back surface of the substrate, and a plurality of main grids located on a surface of the second passivation layer, the plurality of main grids being arranged at intervals in a first direction and extending along a second direction, the main grid including a plurality of pads arranged at intervals in the second direction; each of the welding strips is in electrical contact with a corresponding one of the main grids, the welding strips include a plurality of folds arranged successively in the second direction, and in the second direction, an orthogonal projection of a center line of each of the welding strips on a rear surface of the battery cell is superimposed on a center line of the corresponding main grid and / or a center line of each of the pads on the corresponding main grid on the rear surface of the battery cell; a ratio of a length of the bent portion in a bending direction to a length of the bent portion in the second direction is 1.05 to 1.25; the photovoltaic module includes a plurality of solder resist areas, the solder resist areas being obtained by partitioning the main grid connection lines using the pads of the main grid as partitions and arranged in a second direction, and the solder resist areas are coated with a solder resist ink; the solder resist area includes a plurality of solder resist sub-areas, each of the solder resist sub-areas is coated with the solder resist ink, and the position of each of the solder resist sub-areas corresponds to the position of an isotropic sub-grid having a polarity opposite to that of the main grid; A photovoltaic module comprising:

2. In the second direction, the bending directions of adjacent bending portions are the same or opposite.

2. The photovoltaic module of claim 1.

3. The shape of the bent portion includes an arc shape, a square shape, or a broken line shape.

2. The photovoltaic module of claim 1.

4. each of the pads electrically contacts two adjacent folds of the welding strip; 2. The photovoltaic module of claim 1.

5. The folding portion includes a first folding portion electrically contacting a corresponding one of the pads and a second folding portion not electrically contacting any of the pads, the size of the first folding portion is larger than the size of the second folding portion in a third direction, and the third direction is perpendicular to the folding direction of the folding portion.

5. A photovoltaic module according to claim 4.

6. In a fourth direction, a distance between a bending apex of the bending portion away from the main grid and the main grid is 0.1 mm to 0.3 mm, and the fourth direction is perpendicular to the second direction.

2. The photovoltaic module of claim 1.

7. The lengths of the plurality of bent portions in the second direction are the same.

2. The photovoltaic module of claim 1.

8. a plane on which each of the welding strips lies is parallel to a rear surface of the battery cell; 8. A photovoltaic module according to claim 1, wherein the photovoltaic module is a photovoltaic module.

9. the thickness of the solder resist ink is 15 μm or more higher than the height of the solder resist area or the solder resist sub-area, and the width of the solder resist ink is 50 μm or more wider than the width of the solder resist area or the solder resist sub-area; 2. The photovoltaic module of claim 1.

10. The solder resist ink is an insulating adhesive.

2. The photovoltaic module of claim 1.

11. A method for manufacturing a photovoltaic module, comprising the steps of: providing a plurality of battery cells, the battery cells including: a substrate having opposing front and back surfaces; a first passivation layer located on the front surface of the substrate; a second passivation layer located on the back surface of the substrate; and a plurality of main grids located on a surface of the second passivation layer, the plurality of main grids being arranged at intervals in a first direction and extending along a second direction, the main grid including a plurality of pads arranged at intervals in the second direction; providing a plurality of welding strips and successively shaping the welding strips using a shaping process to form successively arranged folds in the second direction; In the second direction, aligning an orthogonal projection of a center line of each of the welding strips on a rear surface of the battery cell with a center line of a corresponding one of the main grids and / or a center line of each of the pads on the corresponding one of the main grids on the rear surface of the battery cell, and electrically contacting each of the welding strips to the corresponding one of the main grids using an electrical connection process to form a cell string in which adjacent battery cells are connected via the welding strips; providing at least one sealing layer and at least one cover plate, disposing the at least one sealing layer on a surface of the at least one cell string, disposing the at least one cover plate on a surface of the at least one sealing layer away from the at least one cell string, and then laminating and molding; wherein the ratio of the length of the bent portion in the bending direction to the length of the bent portion in the second direction is 1.05 to 1.25; the photovoltaic module includes a plurality of solder resist areas, the solder resist areas being obtained by partitioning the main grid connection lines using the pads of the main grid as partitions and arranged in a second direction, and the solder resist areas are coated with a solder resist ink; the solder resist area includes a plurality of solder resist sub-areas, each of the solder resist sub-areas is coated with the solder resist ink, and the position of each of the solder resist sub-areas corresponds to the position of an isotropic sub-grid having a polarity opposite to that of the main grid; A method for manufacturing a photovoltaic module comprising the steps of:

12. The shaping process includes bending, folding, forging or pressing. The method for manufacturing a photovoltaic module according to claim 11 .

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