Photovoltaic module and method for preparing photovoltaic module

Abstract

An embodiment of the present application relates to a photovoltaic module and a method for manufacturing a photovoltaic module. The photovoltaic module includes: a battery string, the battery string includes a plurality of battery cells, and adjacent battery cells are connected by welding tapes; the battery cell includes a substrate, the substrate has opposite front and back surfaces, a first passivation layer on the front surface of the substrate, a second passivation layer on the back surface of the substrate, a plurality of main grids on the surface of the second passivation layer, the plurality of main grids are arranged at intervals along a first direction and extend along a second direction, and the main grid includes a plurality of pads arranged at intervals along the second direction; a plurality of welding tapes, and each welding tape is in electrical contact with a corresponding main grid respectively, the welding tape includes a plurality of bending portions arranged continuously along the second direction, and in the second direction, the orthographic projections of the center lines of the respective welding tapes on the back surface of the battery cell coincide with the center lines of the corresponding main grids and / or the orthographic projections of the center lines of each pad on the corresponding main grid on the back surface of the battery cell respectively. This is beneficial to improving the yield of the battery string and reducing the production cost.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of solar cells, and in particular, to a photovoltaic module and a method for manufacturing the photovoltaic module. Background Art

[0002] Solar cells have good photoelectric conversion ability. Therefore, solar cells are the focus of the development of clean energy. Since the positive and negative metal electrodes of the all-back-contact solar cell are both arranged on the back of the cell and there is no grid line occlusion on the front of the cell, the shading current loss of the metal electrode can be eliminated, and the maximum utilization of incident photons can be achieved, which has good prospects. Therefore, the photovoltaic module constructed by the all-back-contact solar cell has good application prospects.

[0003] However, in the current design scheme of the photovoltaic module, the cell is prone to problems such as hidden cracks and fragments, which in turn lead to low yield and high manufacturing cost of the photovoltaic module. Summary of the Invention

[0004] The embodiments of the present application provide a photovoltaic module and a method for manufacturing the photovoltaic module, which are at least beneficial to releasing the stress when the solder ribbon is in electrical contact with the cell, improving the yield of the photovoltaic module, and reducing the manufacturing cost.

[0005] The embodiments of the present application provide a photovoltaic module, including: a battery string, the battery string includes a plurality of cells, and adjacent cells are connected by solder ribbons; the cell includes a substrate, the substrate has opposite front and back surfaces, a first passivation layer on the front surface of the substrate, a second passivation layer on the back surface of the substrate, a plurality of main grids on the surface of the second passivation layer, the plurality of main grids are spaced apart along a first direction and extend along a second direction, and the main grid includes a plurality of pads spaced apart along the second direction; a plurality of solder ribbons, and each solder ribbon is in electrical contact with a corresponding main grid respectively, the solder ribbon includes a plurality of bending portions arranged continuously along the second direction, and in the second direction, the orthographic projection of the center line of each solder ribbon on the back surface of the cell coincides with the center line of the corresponding main grid and / or the orthographic projection of the center line of each pad on the corresponding main grid on the back surface of the cell.

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

[0007] In addition, the shape of the bending portion includes an arc shape, a U shape or a zigzag shape.

[0008] In addition, each pad is in electrical contact with two adjacent bending portions on the solder ribbon respectively.

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

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

[0011] In addition, 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] In addition, the lengths of the plurality of bent portions in the second direction are the same.

[0013] In addition, the plane where each solder ribbon is located is parallel to the back surface of the cell.

[0014] Correspondingly, an embodiment of the present application further provides a method for manufacturing a photovoltaic module, including: providing a plurality of cells, each cell including a substrate having opposite front and back surfaces, a first passivation layer on the front surface of the substrate, a second passivation layer on the back surface of the substrate, a plurality of main grids on the surface of the second passivation layer, the plurality of main grids being spaced apart in a first direction and extending in a second direction, the main grid including a plurality of pads spaced apart in the second direction; providing a plurality of solder ribbons, continuously shaping the solder ribbons by a shaping process to form bent portions arranged continuously along the extending direction; in the second direction, aligning the orthographic projection of the center line of each solder ribbon on the back surface of the cell with the center line of the corresponding main grid and / or the orthographic projection of the center line of each pad on the corresponding main grid on the back surface of the cell, and using an electrical connection process to electrically contact each solder ribbon with the corresponding main grid respectively to form a battery string in which adjacent cells are connected by the solder ribbons; providing a packaging layer and a cover plate, and laminating and forming after placing the packaging layer on the surface of the battery string and placing the cover plate on the surface of the packaging layer away from the battery string.

[0015] In addition, the shaping process includes bending, folding, forging or stamping.

[0016] The technical solution provided by the embodiment of the present application has at least the following advantages:

[0017] In the technical solution of the photovoltaic module provided by the embodiment of the present application, after arranging in an orderly manner the full-back contact solar cells with a suede surface formed by a first passivation layer on the front surface of a plurality of substrates and a second passivation layer with a main grid including a plurality of main grids arranged at intervals in a first direction and extending in a second direction on the back surface of the substrates, each solder strip formed by a plurality of bending portions continuously arranged in the second direction is respectively in electrical contact with the corresponding main grid, so as to form a battery string by connecting adjacent solar cells with the solder strip. The solder strip formed by continuously arranged bending portions is used to connect adjacent solar cells, and the bending portions are used as buffer sections to fully release the stress during the process of connecting the solar cells with the solder strip, avoiding warping of the solar cells and improving the reliability and yield rate of the battery string; the main grid includes a plurality of pads arranged at intervals in the second direction. During the process of connecting adjacent solar cells with the solder strip, in the second direction, first align the projection of the center line of each solder strip on the back surface of the solar cell with the projection of the center line of the corresponding main grid and / or the projection of the center line of each pad on the corresponding main grid on the back surface of the solar cell, so that the projection of the center line of the solder strip coincides with the projection of the center line of the main grid and / or the projection of the center line of each pad on the main grid. Then, electrically contact the solder strip with the corresponding main grid to complete the production of the battery string. By making the projection of the center line of the solder strip on the back surface of the solar cell coincide with the projection of the center line of the main grid and / or the projection of the center line of each pad on the main grid on the back surface of the solar cell, the aesthetic degree and connection effect during the connection of solar cells with the solder strip are ensured, and it is avoided that the solder strip deviates out of the main grid area, resulting in an increase in contact resistance and affecting the efficiency of the battery string. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] One or more embodiments are illustrated by way of example in the accompanying drawings, and these illustrative descriptions do not limit the embodiments unless otherwise stated. The figures in the drawings do not constitute a scale limitation.

[0019] Figure 1 FIG. [X] is a schematic structural diagram of a battery string provided by an embodiment of the present application;

[0020] Figure 2 FIG. [X] is a schematic structural diagram of the grid lines of a solar cell provided by an embodiment of the present application;

[0021] Figure 3 FIG. [X] is a schematic structural diagram of a solder strip provided by an embodiment of the present application;

[0022] Figure 4 FIG. [X] is a schematic structural diagram of a solar cell provided by an embodiment of the present application;

[0023] Figure 5 FIG. [X] is a schematic structural diagram of various solder strips respectively formed by different bending portions provided by an embodiment of the present application;

[0024] Figure 6Schematic diagram of a structure of a plurality of solder tapes formed by different bent portions provided in an embodiment of the present application;

[0025] Figure 7 Schematic diagram of a structure of an electrical contact between a solder tape and a pad provided in an embodiment of the present application;

[0026] Figure 8 Schematic diagram of a structure of a main grid including a solder mask region provided in an embodiment of the present application;

[0027] Figure 9 Schematic diagram of another structure of an electrical contact between a solder tape and a pad provided in an embodiment of the present application;

[0028] Figure 10 Schematic diagram of yet another structure of an electrical contact between a solder tape and a pad provided in an embodiment of the present application

[0029] Figure 11 Flow chart of a method for manufacturing a photovoltaic module provided in another embodiment of the present application;

[0030] Figure 12 Schematic diagram of a structure of a photovoltaic module provided in an embodiment of the present application. Detailed implementation manners

[0031] As can be seen from the background art, in the existing photovoltaic modules, the battery chips are prone to hidden cracks or fragmentation, which in turn causes problems such as low yield and high manufacturing cost of the photovoltaic modules.

[0032] An embodiment of the present application provides a photovoltaic module. When constructing a battery string using a plurality of fully back - contacted battery chips, after arranging the battery chips neatly, a solder tape formed by a plurality of bent portions continuously arranged along a second direction is used to connect adjacent battery chips. The bent portions are used as buffer joints to fully release the stress during the process of connecting the battery chips with the solder tape, avoiding warping of the battery chips and improving the reliability and yield of the battery string. During the process of connecting adjacent battery chips with the solder tape, along the second direction, first, the projection of the center line of each solder tape on the back surface of the battery chip is aligned with the projection of the center line of the corresponding main grid and / or the projection of the center line of each pad on the corresponding main grid on the back surface of the battery chip, so that the projection of the center line of the solder tape coincides with the projection of the center line of the main grid and / or the projection of the center line of each pad on the main grid. Then, the solder tape is electrically contacted with the corresponding main grid to complete the production of the battery string. By making the projection of the center line of the solder tape on the back surface of the battery chip coincide with the projection of the center line of the main grid and / or the projection of the center line of each pad on the main grid on the back surface of the battery chip, the aesthetic degree and connection effect during the connection of the battery chips using the solder tape are ensured, and the contact resistance is prevented from rising due to the solder tape shifting out of the main grid area, thereby affecting the efficiency of the battery string.

[0033] The embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present application, many technical details are provided to help readers better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0034] Reference Figures 1 to 4 , wherein, Figure 1 is a schematic diagram of the back surface structure of the battery string 101, Figure 2 is a schematic diagram of the grid line structure on the back surface of the battery cell 102, Figure 3 is an enlarged schematic diagram of the welding ribbon 103, Figure 4 is a schematic diagram of the battery structure of the battery cell 102. The photovoltaic module includes: a battery string 101, the battery string 101 includes a plurality of battery cells 102, and adjacent battery cells 102 are connected by welding ribbons 103; the battery cell 102 includes a substrate 1021, the substrate 1021 has opposite front and back surfaces, a first passivation layer 1022 on the front surface of the substrate 1021, a second passivation layer 1023 on the back surface of the substrate 1021, a plurality of main grids 1024 on the surface of the second passivation layer 1023, the plurality of main grids 1024 are arranged at intervals along a first direction and extend along a second direction, the polarities of adjacent main grids 1024 are opposite, and are respectively connected to auxiliary grids with the same polarity; the main grid 1024 includes a plurality of pads 1025 arranged at intervals along the second direction; a plurality of welding ribbons 103, and each welding ribbon 103 is in electrical contact with the corresponding main grid 1024 respectively, the welding ribbon 103 includes a plurality of bent portions arranged continuously along the second direction, in the second direction, the orthogonal projection of the center line of each welding ribbon 103 on the back surface of the battery cell 102 coincides with the center line of the corresponding main grid 1024, and / or the orthogonal projection of the center line of each pad 1025 on the corresponding main grid 1024 on the back surface of the battery cell 102, wherein, the X direction is the first direction, and the Y direction is the second direction.

[0035] It should be understood that the above embodiment gives an exemplary example of the electrical contact between the welding ribbon 103 and the main grid 1024. In specific applications, considering the possible deviations of each pad 1025 during the production of the main grid 1024 and the difficulty of achieving complete alignment of the center lines, when the center line of the welding ribbon 103 coincides with the center line of the main grid 1024, and / or coincides with the center line of each pad 1025 on the main grid 1024, a certain coincidence deviation between the center lines is allowed. For example, in the direction perpendicular to the second direction, there is a 10% or 20% offset between the center lines, that is, the coincidence area of the center lines accounts for 90% or 80% of the total area of the center lines, while reducing the application difficulty of the solution as much as possible to ensure the electrical contact effect.

[0036] During the process of constructing the battery string 101 using a back-contact cell in which multiple main grids 1024 are all disposed on the second passivation layer 1023 on the back surface of the cell 102, a solder ribbon 103 including a plurality of bending portions continuously arranged in the second direction is used to connect adjacent cells 102. Thus, when welding each solder ribbon 103 to the corresponding main grid 1024 to achieve electrical contact between the two, the multiple continuous bending portions of the solder ribbon 103 are used as multiple buffer joints to release the welding stress generated due to the inconsistent shrinkage amounts of the solder ribbon 103 and the cell 102 after welding because they have different coefficients of thermal expansion, ensuring the welding effect when the solder ribbon 103 connects adjacent cells 102, avoiding warping of the cell 102, and improving the yield rate of the battery string 101. During the process of electrically contacting the solder ribbon 103 with the corresponding main grid 1024, in the second direction, the orthogonal projection of the center line of each solder ribbon 103 on the back surface of the cell 102, the center line of the main grid 1024 corresponding to the solder ribbon 103, and / or the orthogonal projection of the center line of each solder pad 1025 on the main grid 1024 corresponding to the solder ribbon 103 on the back surface of the cell 102 are aligned. After the orthogonal projection of the center line of the solder ribbon 103 and the center line of the main grid 1024 corresponding to the solder ribbon 103, and / or the center lines of each solder pad 1025 on the main grid 1024 corresponding to the solder ribbon 103 coincide, through an electrical connection process, such as welding, each solder ribbon 103 is electrically contacted with the corresponding main grid 1024 respectively, thereby connecting adjacent cells 102 to form the battery string 101. By aligning the center line of the solder ribbon 103 with the center line of the main grid 1024 or the center lines of each solder pad 1025 on the main grid 1024, the aesthetics and connection effect when using the solder ribbon 103 to connect the cells 102 are ensured, and the contact resistance between the solder ribbon 103 and the main grid 1024 is prevented from increasing due to the solder ribbon 103 shifting out of the area where the main grid 1024 is located, which affects the efficiency of the battery string 101.

[0037] The substrate 1021 is used to receive incident light and generate photo-generated carriers. In some embodiments, the substrate 1021 can be a silicon substrate, and the material of the silicon substrate can include at least one of single-crystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In other embodiments, the material of the substrate 1021 can also be silicon carbide, an organic material, or a multiple compound. The multiple compound can include, but is not limited to, materials such as perovskite, gallium arsenide, cadmium telluride, copper indium selenide, etc.

[0038] In addition, the first direction and the second direction may be perpendicular to each other, or there may be an angle less than 90 degrees, for example, 60 degrees, 45 degrees, 30 degrees, etc., as long as the first direction and the second direction are not the same direction. For the sake of ease of description and understanding, this embodiment is described by taking the first direction and the second direction being perpendicular to each other as an example. In specific applications, the angle between the first direction and the second direction may be adjusted according to actual needs and application scenarios, and this embodiment does not limit this.

[0039] In some embodiments, the shape of the bending portion includes an arc, a figure-shaped, or a broken line. Figure 2 and Figure 5 ,in, Figure 5 The structural schematic diagrams of various welding strips 103 composed of an arc-shaped bending portion 501, an X-shaped bending portion 502 and a folded line bending portion 503 are shown in sequence.

[0040] During the shaping process of the solder strip 103, the shape of the bent portion formed by shaping can be set according to the scene requirements. For example, in the case where the thermal expansion coefficients between the battery cell 102 and the solder strip 103 are very different, in order to maximize the stress release capacity of each bent portion on the solder strip 103, when the bending degree is consistent, that is, when the bending vertex farthest from the center line of the solder strip 103 along the second direction is consistent with the center line, the shape of the bent portion can be set to an arc or a "J" shape, so as to maximize the ratio of the length of the bent portion along the bending direction to the length of the bent portion along the first direction, thereby improving the stress release capacity of the bent portion. In the case where the difference in thermal expansion coefficient between the cell 102 and the soldering ribbon 103 is small, and other conditions such as the bending degree are the same, in order to reduce the coverage area of the soldering ribbon 103 on the back surface of the cell 102 as much as possible, the shape of the bending portion can be set to a broken line shape, such as a triangle, rectangle or trapezoid, to avoid the soldering ribbon 103 from contacting the secondary grid on the back surface of the cell 102 to cause a short circuit, thereby ensuring the insulation degree of the battery string 101. In the case where other conditions are the same and it is necessary to take into account both the stress release capability of the soldering ribbon 103 and the reduction of the coverage area of the soldering ribbon 103 on the back surface of the cell 102, the shape of the bending portion can be set to an arc shape with a smaller area of the back surface of the cell 102 occupied by the soldering ribbon 103; in the case where it is necessary to increase the stress release capability of the soldering ribbon 103 as much as possible, the shape of the bending portion can be set to a "X" shape with a larger area of the back surface of the cell 102 occupied by the soldering ribbon 103. According to the application scenarios and requirements, an appropriate shape is selected from a variety of bending portion shapes to shape the soldering strip 103, so as to ensure the adaptability of the soldering strip 103 to different application scenarios and requirements.

[0041] It should be understood that the arc in the shape of the bending portion can be an irregular arc composed of a circular arc, an elliptical arc or multiple arcs; the broken line shape can be a triangle, a rectangle or a trapezoid and other figures composed of multiple broken lines; the "J" shape can be a smooth figure composed of multiple arcs, or a figure composed of multiple broken lines and multiple arcs, or a figure similar to a normal distribution curve. This embodiment does not limit the specific structure of bending portions of different shapes.

[0042] In some embodiments, along the second direction, the bending directions of adjacent bending portions are the same or opposite. Figure 6 , Figure 6 The structural schematic diagrams of various welding strips 103 are shown in sequence, in which the bending directions of adjacent arc-shaped bending portions are the same and opposite, and the bending directions of adjacent S-shaped bending portions are the same and opposite along the second direction.

[0043] In the process of shaping the welding strip 103, the relationship between the bending directions of adjacent bending portions can be adjusted as needed. When other conditions such as the bending degree and the width of the welding strip 103 itself are consistent, in order to make the coverage area of the welding strip 103 on the back surface of the battery cell 102 as small as possible, in the process of constructing the welding strip 103, two adjacent bending portions can be bent in the same bending direction to reduce the coverage area of the welding strip 103 on the back surface of the battery cell 102, and minimize the contact between the welding strip 103 and the secondary grid on the back surface of the battery cell 102, thereby avoiding short circuit on the battery cell 102; in order to make the welding strip 103 have a good stress release effect, in the process of constructing the welding strip 103, two adjacent bending portions can be bent in opposite bending directions. Since the bending portions in the welding strip 103 are alternately arranged along different bending directions, the bending portions in the welding strip 103 can have a good release effect on stress in more directions, and the overall shape of the welding strip 103 will be as smooth and beautiful as possible. Therefore, the bending directions of adjacent bending portions in the welding strip 103 can be set to be the same or opposite to each other to adapt to different application scenarios and requirements.

[0044] It should be understood that this embodiment is for ease of understanding, and the relationship between the bending directions of adjacent bending portions is described as an example. However, in specific applications, along the second direction, the relationship between the bending directions of adjacent bending portions in the welding strip 103 can be consistent, that is, the bending directions of all adjacent bending portions are the same or opposite; the relationship between the bending directions of adjacent bending portions can also be inconsistent, that is, the bending directions of some adjacent bending portions are the same, and the bending directions of some adjacent bending portions are opposite. This embodiment does not impose any restrictions on this.

[0045] In some embodiments, each pad 1025 is electrically connected to two adjacent bends on the solder ribbon 103. Figure 2 and Figure 7, the welding ribbon 103 is composed of arc-shaped bending parts 501 with opposite bending directions of adjacent bending parts. Each pad 1025 is in contact with two adjacent bending parts on the welding ribbon 103, and in the first direction, the intersection line of the two arc-shaped bending parts 501 coincides with the center line of the pad 1025. That is to say, before the welding ribbon 103 is in electrical contact with the main grid 1024, in the second direction, after aligning the positive projection of the center line of the welding ribbon 103 on the back surface of the battery cell 102 with the center line of the main grid 1024, and / or the positive projection of the center lines of the pads 1025 on the main grid 1024 on the back surface of the battery cell 102, it is also possible to align the intersection line between the adjacent bending parts connected to the pad 1025 with the center line of the pad 1025 in the direction perpendicular to the second direction, and then use an electrical connection process to make the pad 1025 in electrical contact with the two adjacent bending parts, thus completing the electrical contact between the welding ribbon 103 and the corresponding main grid 1024. Since the pad 1025 is in electrical contact with the two adjacent bending parts, when the welding ribbon 103 and the battery cell 102 have different shrinkage amounts due to the difference in the coefficient of thermal expansion, the pad 1025 can directly release the stress generated by the different shrinkage amounts of the welding ribbon 103 and the battery cell 102 by means of the two adjacent bending parts in electrical contact with itself, improving the stress release ability and effect.

[0046] It should be understood that in the above embodiment, only a schematic structural diagram of the electrical contact between the pad 1025 and the welding ribbon 103 is given. In the process of making the pad 1025 in electrical contact with the two adjacent bending parts of the welding ribbon 103, considering factors such as the implementation difficulty and mechanical error, in the direction perpendicular to the second direction, not only can the intersection line between the bending parts 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 not completely coincident or separated. For example, the overlapping area of the center line of the pad 1025 and the intersection line of the adjacent bending parts accounts for 90%, 80% or 50% of the total area, etc., or in the second direction, the interval between the intersection line of the adjacent bending parts and the center line is 10%, 20% or 45% of the maximum length of the pad 1025, etc. On the basis of ensuring the stress release effect, the implementation difficulty of making the welding ribbon 103 in electrical contact with the pad 1025 is reduced, and in this embodiment, the specific positional relationship between the intersection line of the bending parts and the center line of the pad 1025 along the second direction when the pad 1025 is in electrical contact with the two adjacent bending parts of the welding ribbon 103 is not limited.

[0047] In addition, referring to Figure 2 and Figure 8, the main grid 1024 includes a main grid connection line 801 and a pad 1025. To avoid the secondary grid on the back surface of the cell 102 from making electrical contact with the opposite-sex main grid 1024 having the opposite polarity to itself, or the solder tape 103 corresponding to the opposite-sex main grid 1024 having the opposite polarity to itself, before connecting the cells 102, it is also possible to perform solder mask treatment on each main grid 1024 on the back surface of each cell 102 in advance. Taking each pad 1025 on the main grid 1024 as a separator, the main grid connection line 801 is divided into multiple solder mask regions 802 arranged along the second direction, and then a solder mask ink, such as an insulating glue, is used to perform solder mask treatment on the solder mask regions 802 by means of printing or dispensing. During the solder mask treatment process, each solder mask region 802 can be completely covered with the solder mask ink, or multiple solder mask sub-regions 803 can be divided in the solder mask region 802 and each solder mask sub-region 803 can be completely covered. Among them, the positions of the solder mask sub-regions 803 correspond to the positions of the opposite-sex secondary grids having the opposite polarity to the main grid 1024, so as to avoid the solder tape 103, the main grid 1024, and the secondary grid having the opposite polarity to the main grid 1024 from coming into contact. During the solder mask treatment process, the size of the solder mask ink should satisfy that the thickness is 15 μm or more higher than the height of the solder mask region 802 or the solder mask sub-region 803, and the width is 50 μm or more wider than the width of the solder mask region 802 or the solder mask sub-region 803. The specific size of the solder mask ink in this embodiment is not limited.

[0048] Reference Figure 2 and Figure 9 , where the third direction is the Z direction. In some embodiments, the bent portion includes a first bent portion 901 in electrical contact with the pad 1025 and a second bent portion 902 not in electrical contact with the pad 1025. In the third direction, the size of the first bent portion 901 is larger than the size of the second bent portion 902, and the third direction is perpendicular to the bending direction of the bent portion.

[0049] The main function of the solder tape 103 is to connect adjacent cells 102 and transmit the current collected on the main grid 1024 in electrical contact with the solder tape 103 to the component end connected to the battery string 101. The current transmission ability of the solder tape 103 is related to its own resistance and the contact resistance between the solder tape 103 and the main grid 1024. When the solder tape 103 is in electrical contact with the main grid 1024 through each pad 1025 on the main grid 1024, the contact resistance between the solder tape 103 and the main grid 1024 is related to the contact area between the solder tape 103 and the pad 1025.

[0050] Therefore, during the process of shaping the solder strip 103 to form the bending portion, after the solder strip 103 forms a plurality of continuously arranged bending portions along the second direction, the solder strip 103 can be aligned with the corresponding main grid 1024, and the first bending portion 901 in the solder strip 103 that is in electrical contact with the pad 1025 and the second bending portion 902 that is not in electrical contact with the pad 1025 can be determined. In the third direction, the sizes of the first bending portion 901 and the second bending portion 902 respectively refer to their widths in the third direction. Therefore, the third direction is a direction parallel to the back surface of the cell 102 and perpendicular to the second direction. When the original width of the solder strip 103 along the vertical extension direction is relatively small before shaping, the first bending portion 901 is stretched in the third direction perpendicular to the bending direction, so that in the third direction of the solder strip 103, the size of the first bending portion 901 is larger than that of the second bending portion 902; when the original width of the solder strip 103 along the vertical extension direction is relatively large before shaping, the second bending portion 902 is compressed in the third direction perpendicular to the bending direction, so that in the third direction, the size of the first bending portion 901 is larger than that of the second bending portion 902. The first bending portion 901 or the second bending portion 902 in the solder strip 103 is subjected to secondary shaping, so that in the third direction perpendicular to the bending direction, the size of the first bending portion 901 is larger than that of the second bending portion 902, and then the adjacent first bending portions 901 are connected to the corresponding pads 1025 to complete the electrical contact between the solder strip 103 and the corresponding main grid 1024.

[0051] In the third direction perpendicular to the bending direction, the size of the first bending portion 901 in the solder strip 103 that is in electrical contact with the pad 1025 is set larger, which increases the electrical contact area between the solder strip 103 and the pad 1025, thereby reducing the contact resistance between the two, and thus improving the current transmission capacity of the solder strip 103 and ensuring the working efficiency of the battery string 101.

[0052] Reference reference Figure 2 and Figure 10 , where the fourth direction is the F direction. In some embodiments, in the fourth direction, the interval between the bending vertex 1001 of the bending portion away from the main grid 1024 and the main grid 1024 is 0.1 mm to 0.3 mm, and the fourth direction is perpendicular to the second direction.

[0053] Figure 10Among them, the solder ribbon 103 is composed of arc-shaped bending parts with opposite bending directions of adjacent bending parts. Along the fourth direction, the distance between the bending vertex 1001 of the bending part and the main grid 1024 is the minimum distance from the positive projection of the bending vertex 1001 on the back surface of the battery chip 102 to the center line of the positive projection of the main grid 1024 on the back surface of the battery chip 102. That is to say, the fourth direction is a direction parallel to the back surface of the battery chip 102 and perpendicular to the second direction. When the distance between the bending vertex 1001 and the main grid 1024 is too small along the fourth direction, the bending degree of the bending part is low, which will reduce the ability of the bending part to release the stress generated between the solder ribbon 103 and the battery chip 102. Furthermore, it is easy to occur that the stress is not effectively released, resulting in warping or even fragmentation of the battery chip 102, affecting the yield rate and production cost of the battery string 101; when the distance between the bending vertex 1001 and the main grid 1024 is too large, the bending degree of the bending part is very high, the ability of the bending part to release the stress generated between the solder ribbon 103 and the battery chip 102 exceeds the requirement, and at the same time, the overall length of the solder ribbon 103 is too large, reducing the current transmission ability of the solder ribbon 103. And when the bending degree is too high, the solder ribbon 103 is easily in electrical contact with the opposite-sex auxiliary grid on the back surface of the battery chip 102 with the opposite polarity to its corresponding main grid 1024, affecting the insulation of the battery chip 102.

[0054] Therefore, along the fourth direction, the distance between the bending vertex 1001 of the bending part of the solder ribbon 103 far 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 bending part can effectively release the stress generated between the solder ribbon 103 and the battery chip 102, improve the yield rate of the battery string 101, and at the same time ensure the current transmission ability of the solder ribbon 103 and the insulation of the battery chip 102.

[0055] 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 core function of the bent portion is to release the stress generated between the solder tape 103 and the battery cell 102 as a buffer section. The stress release ability of the bent portion is related not only 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 extending direction, that is, related to 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 the condition that other conditions are the same, when 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 amount of stress that the bent portion can release is quite limited, restricting the ability of the bent portion to release the stress generated between the solder tape 103 and the battery cell 102, resulting in a limited stress release effect, and it is still easy for the battery cell 102 to warp or even break, affecting the yield rate and production cost of the battery string 101; when 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 stress that the bent portion can release is very large, the ability of the bent portion to release the stress generated between the solder tape 103 and the battery cell 102 exceeds the requirement, at the same time, the overall length of the solder tape 103 is too large, reducing the current transmission ability of the solder tape 103, and increasing the production cost of the battery string 101.

[0056] Therefore, the ratio of the length of the bent portion in the bending direction to the length of the bent portion in the second direction in the solder tape 103 can be set to 1.05 to 1.25, for example, 1.10, 1.15 or 1.20, etc., so that while the bent portion can effectively release the stress generated between the solder tape 103 and the battery cell 102 and improve the yield rate of the battery string 101, the current transmission ability of the solder tape 103 is ensured, and the problem of too high production cost of the battery string 101 is avoided.

[0057] In some embodiments, the lengths of multiple bent portions in the second direction are the same. As described in the above embodiments, the core function of the bent portion is to release the stress generated between the solder tape 103 and the battery cell 102 as a buffer section, and the materials used for manufacturing each main grid 1024 on the battery cell 102 are generally the same. When the solder tape 103 is in electrical contact with the main grid 1024, the amount of stress to be released at each contact position is basically the same. Therefore, the lengths of the bent portions in the second direction can be set to the same length. While ensuring the stress release effect and aesthetic degree, the regular distribution and the same specifications of the bent portions are also convenient for shaping and manufacturing the solder tape 103, reducing the shaping difficulty of the solder tape 103, and improving the efficiency of shaping and production.

[0058] It should be understood that when a special structure or requirement is provided on the battery cell 102, the length of a specific bent portion in the second direction can also be set individually according to the requirements of the application scenario. Moreover, considering production efficiency and the difficulty and accuracy of actual production, there may be a certain deviation between the lengths of the bent portions in the second direction and a preset standard length. For example, the deviation between the actual length and the standard length can be 5%, 10%, 15%, etc. This embodiment does not limit this.

[0059] In some embodiments, the plane where each solder ribbon 103 is located is parallel to the back surface of the battery cell 102. During the shaping process of the solder ribbon 103, a plurality of bent portions arranged continuously along the extending direction are formed on a plane parallel to the back surface of the battery cell 102. And when using the solder ribbon 103 to connect the battery cell 102, the plane where each bent portion of the solder ribbon 103 is located is placed parallel to the back surface of the battery cell 102, and the solder ribbon 103 is electrically contacted with the main grid 1024 through an electrical connection technique. Placing the plane where the solder ribbon 103 is located parallel to the back surface of the battery cell 102 avoids the problem of the presence of protrusions or depressions on the solder ribbon 103 in the direction perpendicular to the back surface of the battery cell 102. It avoids the problem of the increase in the maximum height of the battery string 101 caused by the presence of protrusions, reduces the accommodation volume required for the battery string 101, and thus reduces the volume of the photovoltaic module. At the same time, it avoids the problem that the solder ribbon 103 is prone to scratching the battery cell 102 and the main grid 1024 when there are depressions, and ensures the integrity of the grid lines of the battery cell 102 and the overall photoelectric conversion efficiency of the battery cell 102.

[0060] Correspondingly, another embodiment of the present application further provides a method for manufacturing a photovoltaic module. This method for manufacturing a photovoltaic module can form the photovoltaic module provided in the previous embodiment. The specific process of the manufacturing method can refer to Figure 11 , including:

[0061] Refer to Figure 2 and Figure 4 to provide a plurality of battery cells 102.

[0062] The battery cell 102 includes a substrate 1021. The substrate 1021 has opposite front and back surfaces, a first passivation layer 1022 on the front surface of the substrate 1021, a second passivation layer 1023 on the back surface of the substrate 1021, and a plurality of main grids 1024 on the surface of the second passivation layer 1023. The plurality of main grids 1024 are arranged at intervals in the first direction and extend in the second direction. The main grid 1024 includes a plurality of solder pads 1025 arranged at intervals in the second direction.

[0063] Refer to Figure 3, a plurality of solder tapes 103 are provided, and the solder tapes 103 are continuously shaped by a shaping process to form bent portions arranged continuously along the extending direction. During the process of shaping the solder tapes 103 to form the bent portions, since a continuous shaping method is adopted, there is no need to consider how to set the intervals of the bent portions and the interval dimensions between adjacent bent portions. Therefore, the shaping is simpler and the yield rate of the shaped solder tapes 103 is higher. Moreover, since the solder tapes 103 are composed of continuously arranged bent portions, the appearance of the solder tapes 103 is smoother and more beautiful.

[0064] In some embodiments, the shaping process includes bending, folding, forging or stamping.

[0065] Reference Figures 1 to 3 , determine the placement positions of the solder tapes 103, and form a battery string 101 by an electrical connection process.

[0066] In the second direction, project the center lines of the respective solder tapes 103 onto the back surface of the solar cell 102, and align them with the center lines of the corresponding main grids 1024 and / or the center lines of each pad 1025 on the corresponding main grid 1024 projected onto the back surface of the solar cell 102. By using an electrical connection process, each solder tape 103 is electrically contacted with the corresponding main grid 1024 respectively to form a battery string 101 in which adjacent solar cells 102 are connected by the solder tapes 103.

[0067] Reference Figure 12 , provide an encapsulation layer 120 and a cover plate 130. After placing the encapsulation layer 120 on the surface of the battery string 101 and placing the cover plate 130 on the surface of the encapsulation layer 120 away from the battery string 101, perform lamination molding.

[0068] The finally formed photovoltaic module may include: a battery string 101 formed by a plurality of solar cells 102, and the battery string 101 is the battery string 101 provided in the above-mentioned embodiments; an encapsulation layer 120 for covering the surface of the solar cells 102; a cover plate 130 for covering the surface of the encapsulation layer 120 away from the solar cells 102, and the plurality of solar cells 102 are electrically connected in series and / or in parallel.

[0069] Specifically, in some embodiments, the plurality of solar cells 102 may be electrically connected by the solder tapes 103. The encapsulation layer 120 covers the front and back surfaces of the solar cells 102. Specifically, the encapsulation layer 120 may be an ethylene-vinyl acetate copolymer (EVA) film, a polyethylene octene copolymer elastomer (POE) film, or a polyethylene terephthalate (PET) film and other organic encapsulation films. In some embodiments, the cover plate 130 may be a glass cover plate, a plastic cover plate or other cover plates 130 with a light-transmitting function. Specifically, the surface of the cover plate 130 facing the encapsulation layer 120 may be an uneven surface, so as to increase the utilization rate of incident light.

[0070] Although the present application is disclosed above with preferred embodiments, it is not intended to limit the claims. Without departing from the concept of the present application, any person skilled in the art can make several possible changes and modifications. Therefore, the protection scope of the present application shall be subject to the scope defined by the claims of the present application.

[0071] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present application. In actual applications, various changes can be made in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make their respective changes and modifications without departing from the spirit and scope of the present application. Therefore, the protection scope of the present application shall be subject to the scope defined by the claims.

Claims

1. A photovoltaic module, characterized in that, Comprising: A battery string, the battery string comprising a plurality of solar cells, and adjacent solar cells being connected by welding tapes; The solar cell comprises a substrate having opposite front and back surfaces, a first passivation layer on the front surface of the substrate, a second passivation layer on the back surface of the substrate, and a plurality of main grids on the surface of the second passivation layer. The plurality of main grids are arranged at intervals in a first direction and extend in a second direction. The main grid comprises a plurality of pads arranged at intervals in the second direction; A plurality of welding tapes, and each welding tape is in electrical contact with a corresponding main grid respectively. The welding tape comprises a plurality of bending portions arranged continuously in the second direction. In the second direction, the orthogonal projection of the center line of each welding tape on the back surface of the solar cell coincides with the center line of the corresponding main grid and / or the orthogonal projection of the center line of each pad on the corresponding main grid on the back surface of the solar cell; Each pad is in electrical contact with two adjacent bending portions on the welding tape respectively; The bending portion comprises a first bending portion in electrical contact with the pad and a second bending portion not in electrical contact with the pad. In a third direction perpendicular to the bending direction of the bending portion, the size of the first bending portion is larger than that of the second bending portion; 2. The photovoltaic module according to claim 1, wherein, In the second direction, the bending directions of adjacent bending portions are the same or opposite; 3. The photovoltaic module according to claim 1, characterized in that, The shape of the bending portion includes an arc shape, a U shape or a zigzag shape; 4. The photovoltaic module according to claim 1, wherein In a fourth direction perpendicular to the second direction, the distance between the bending vertex of the bending portion away from the main grid and the main grid is 0.1 mm to 0.3 mm; 5. The photovoltaic module according to claim 1, wherein The ratio of the length of the bending portion in the bending direction to the length of the bending portion in the second direction is 1.05 to 1.25; 6. The photovoltaic module according to claim 1, wherein The lengths of the plurality of bending portions in the second direction are the same; 7. The photovoltaic module according to any one of claims 1 to 6, characterized in that, The plane where each welding tape is located is parallel to the back surface of the solar cell; 8. A method for preparing a photovoltaic module, characterized in that, Comprising: Providing a plurality of solar cells, the solar cell comprising a substrate having opposite front and back surfaces, a first passivation layer on the front surface of the substrate, a second passivation layer on the back surface of the substrate, and a plurality of main grids on the surface of the second passivation layer. The plurality of main grids are arranged at intervals in a first direction and extend in a second direction. The main grid comprises a plurality of pads arranged at intervals in the second direction; Providing a plurality of welding tapes, and continuously shaping the welding tapes by a shaping process to form bending portions arranged continuously in the extending direction; In the second direction, aligning the orthogonal projection of the center line of each welding tape on the back surface of the solar cell with the center line of the corresponding main grid and / or the orthogonal projection of the center line of each pad on the corresponding main grid on the back surface of the solar cell, and using an electrical connection process to electrically contact each welding tape with the corresponding main grid respectively, so as to form a battery string in which adjacent solar cells are connected by the welding tapes; Wherein, each of the pads is in electrical contact with two adjacent bent portions on the solder tape respectively; the bent portion includes a first bent portion in electrical contact with the pad and a second bent portion not in electrical contact with the pad, and in a third direction perpendicular to the bending direction of the bent portion, the size of the first bent portion is larger than that of the second bent portion. An encapsulation layer and a cover plate are provided. After placing the encapsulation layer on the surface of the battery string and placing the cover plate on the surface of the encapsulation layer away from the battery string, lamination molding is performed.

9. The method for preparing a photovoltaic module according to claim 8, wherein The shaping process includes bending, folding, forging or stamping.

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