Imbricated photovoltaic module and preparation method thereof

Abstract

The invention discloses an imbricated photovoltaic module and a preparation method thereof, and relates to the technical field of solar cells, the imbricated photovoltaic module comprises at least one imbricated cell string, the imbricated cell string comprises a plurality of cells which are sequentially connected in an imbricated manner along a first direction, and the first direction is parallel to a plane where the imbricated photovoltaic module is located; the battery piece comprises an overlapping region and a non-overlapping region which are distributed along a first direction; every two adjacent battery pieces in the first direction are electrically connected and fixed between the overlapping areas through a conductive connecting layer. At least one battery piece is provided with a groove in the overlapping area, and the groove is at least used for increasing the contact area of the conductive connecting layer and the battery piece in the overlapping area. The grooves can increase the contact area, the larger contact area can reduce the contact resistance, the adhesive force between the film layers can be improved, and the connection reliability of the battery pieces and the conductive connection layer can be improved, so that the connection reliability between the two battery pieces which are electrically connected and fixed based on the conductive connection layer is improved.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and particularly relates to an overlapping shingle photovoltaic module and a preparation method thereof. Background Art

[0002] In conventional photovoltaic modules, the cells are generally connected by solder ribbons. The solder ribbon connection method not only results in a large connection impedance between the cells, but also requires a gap for solder ribbon connection between adjacent cells, which reduces the cell density in the photovoltaic module and affects the overall power generation efficiency of the photovoltaic module.

[0003] In an overlapping shingle photovoltaic module, adjacent cells can be connected in an overlapping area by an overlapping shingle method, which reduces the connection impedance between the cells and can also eliminate the gap between adjacent cells, improving the cell density of the photovoltaic module and thus improving the power generation efficiency. However, in the existing overlapping shingle photovoltaic modules, the connection reliability between two adjacent cells in the overlapping area is poor. Summary of the Invention

[0004] In view of the above problems, the present application provides an overlapping shingle photovoltaic module and a preparation method thereof to achieve the purpose of improving the connection reliability between two adjacent cells in the overlapping area. The specific solutions are as follows:

[0005] The first aspect of the present application provides an overlapping shingle photovoltaic module, including:

[0006] At least one overlapping shingle cell string, the overlapping shingle cell string includes a plurality of cells connected in an overlapping shingle manner in a first direction, the first direction is parallel to the plane where the overlapping shingle photovoltaic module is located; the cells include an overlapping area and a non-overlapping area distributed in the first direction; two adjacent cells in the first direction are electrically connected and fixed through a conductive connection layer in the overlapping area;

[0007] At least one cell has a groove in the overlapping area, and the groove is at least used to increase the contact area between the conductive connection layer and the cell in the overlapping area.

[0008] Optionally, in the above overlapping shingle photovoltaic module, the width of the groove increases in the direction from the bottom to the opening of the groove, and the bottom of the groove is a plane.

[0009] Optionally, in the above overlapping shingle photovoltaic module, the groove is an inverted trapezoidal groove, the inclination angle between the side wall and the bottom of the inverted trapezoidal groove is 45° - 75°, the depth of the inverted trapezoidal groove is 20μm - 50μm, and the bottom width of the inverted trapezoidal groove is 40μm - 50μm.

[0010] Optionally, in the above shingled photovoltaic module, the surface of the cell in the overlapping region has grooves extending in a second direction and grooves extending in a third direction, both the second direction and the third direction being parallel to the plane of the cell, so that the grooves extending in the second direction and the grooves extending in the third direction intersect to form a grid structure.

[0011] Optionally, in the above shingled photovoltaic module, for two adjacent cells in a first direction, the two cells are provided with the same grid structure in the overlapping region, and the grid structures on the two cells are arranged in a coincident and opposite manner.

[0012] Optionally, in the above shingled photovoltaic module, the grid structure includes diamond grid units, and one diagonal of the diamond grid unit is parallel to the first direction.

[0013] Optionally, in the above shingled photovoltaic module, the diamond grid unit has a first diagonal and a second diagonal with different lengths;

[0014] For two adjacent cells in a first direction, both of the two cells are provided with a grid structure in the overlapping region, and the centers of the diamond grid units in the two cells are arranged in a coincident and opposite manner. The first diagonal of the diamond grid unit in one cell is parallel to the first direction, and the second diagonal of the diamond grid unit in the other cell is parallel to the first direction.

[0015] Optionally, in the above shingled photovoltaic module, the conductive paste for preparing the conductive connection layer includes a uniformly mixed conductive component, KH-500 silane coupling agent, and ultraviolet light initiator;

[0016] Among them, the conductive component includes silver powder, and also includes graphene and / or carbon nanotubes.

[0017] Optionally, in the above shingled photovoltaic module, the cell has a grid structure formed by grooves in the overlapping region;

[0018] The conductive connection layer is formed by laminating dot-shaped conductive paste located at the grid node positions of the grid structure.

[0019] The second aspect of the present application provides a preparation method for the above-mentioned shingled photovoltaic module, and the preparation method includes:

[0020] Providing cells, the cells including overlapping regions and non-overlapping regions distributed in a first direction; the first direction is parallel to the plane of the shingled photovoltaic module;

[0021] Connecting a plurality of cells in a shingled manner in sequence along the first direction to form a shingled cell string; electrically connecting and fixing the two adjacent cells in the first direction through a conductive connection layer between the overlapping regions.

[0022] Among them, at least one cell has grooves in the overlapping area, and the grooves are at least used to increase the contact area between the conductive connection layer and the cell in the overlapping area.

[0023] With the above technical solution, in the shingled photovoltaic module and its manufacturing method provided by this application, at least one cell is provided with grooves in the overlapping area. Based on the grooves, the contact area between the conductive connection layer and the cell in the overlapping area can be increased. A larger contact area can reduce the contact resistance, can also improve the adhesion between the film layers, and can improve the connection reliability between the cell and the conductive connection layer, so as to improve the connection reliability between the two cells electrically connected and fixed based on the conductive connection layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0025] The structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those who are familiar with this technology to understand and read, and are not used to limit the limited conditions that this application can be implemented. Therefore, they do not have technical substance significance. Any modification of the structure, change of the proportional relationship, or adjustment of the size, without affecting the effects that this application can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in this application.

[0026] Figure 1 It is a cross-sectional view of a shingled photovoltaic module provided by an embodiment of this application;

[0027] Figure 2 It is Figure 1 A top view of a cell in the shingled photovoltaic module shown;

[0028] Figure 3 It is Figure 2 A cross-sectional view along the A-A' direction;

[0029] Figure 4 It is a schematic diagram of the layout principle of a grid structure with a diamond grid unit in a cell;

[0030] Figure 5 It is a schematic diagram of the principle of forming a conductive connection layer of a shingled photovoltaic module provided by an embodiment of this application;

[0031] Figure 6 It is a cross-sectional view of another shingled photovoltaic module provided by an embodiment of this application;

[0032] Figure 7 Another cross-sectional view of the overlapping PV module provided by the embodiment of the present application;

[0033] Figure 8 A schematic flow chart of a method for manufacturing an overlapping PV module provided by the embodiment of the present application.

[0034] Reference numerals:

[0035] 100 - cell; 101 - overlapping area; 102 - non - overlapping area; 103 - conductive connection layer; 104 - groove; 105 - backplane; 106 - adhesive layer; 107 - dot - shaped conductive paste; F1 - first direction; F2 - second direction; F3 - third direction; F4 - fourth direction; L1 - first diagonal; L2 - second diagonal; S1 - first plane. Detailed implementation manners

[0036] Next, the embodiments in the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Those of ordinary skill in the art will know that with the development of technology and the emergence of new scenarios, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems.

[0037] In the context of the rapid development of the photovoltaic industry, overlapping PV modules have gradually become one of the mainstream technical directions in the industry due to their high - efficiency power generation performance and compact structure design. At present, the interconnection of cells in overlapping PV modules is mostly achieved by means of conductive adhesives, solder tapes, etc. These traditional interconnection technologies have played a certain role in improving the energy density and power generation efficiency of modules. However, with the expansion of application scenarios and the improvement of performance requirements, their limitations have become increasingly prominent, and better interconnection technologies are urgently needed to promote the further upgrade of overlapping cell module technologies.

[0038] In an overlapping PV module, after laying cells in an overlapping manner in the overlapping area, adjacent cells can also be electrically connected by solder tapes. Although this method can eliminate the gap between adjacent cells through the overlapping structure, it still needs to use solder tapes to achieve the interconnection between cells. Since solder tape welding requires high - temperature operation, it is easy to cause problems such as hidden cracks and fragments in the cells; moreover, the welding process is complex, with high requirements for equipment and operators, low production efficiency, and increased manufacturing costs.

[0039] To solve the above problems brought by solder tapes, in another overlapping PV module, conductive adhesives can be used to achieve the electrical connection and bonding fixation of adjacent cells in the overlapping area. In this method, due to the poor weather resistance of conductive adhesives during long - term use, in complex environments such as high temperature and high humidity, their conductivity is easily attenuated and the bonding strength decreases, resulting in the failure of cell interconnection and affecting the life of the module.

[0040] Moreover, the internal resistance loss of the shingled photovoltaic module prepared by the current conventional technology is relatively large, the improvement of the energy conversion efficiency is limited, and it is difficult to meet the growing demand for high-efficiency power generation.

[0041] In view of this, the embodiments of the present application provide a shingled photovoltaic module, and the shingled photovoltaic module includes:

[0042] At least one shingled battery string, the shingled battery string includes a plurality of battery wafers sequentially connected in a shingled manner along a first direction, and the first direction is parallel to the plane where the shingled photovoltaic module is located; the battery wafers include an overlapping area and a non-overlapping area distributed along the first direction; two adjacent battery wafers in the first direction are electrically connected and fixed through a conductive connection layer between the overlapping areas;

[0043] At least one battery wafer has a groove in the overlapping area, and the groove is at least used to increase the contact area between the conductive connection layer and the battery wafer in the overlapping area.

[0044] In the embodiments of the present application, the connection and fixation between two adjacent battery wafers are realized through the conductive connection layer between the overlapping areas, and the contact area between the conductive connection layer and the battery wafer can be increased through the grooves on the battery wafers. The larger contact area can reduce the contact resistance, improve the adhesion between the film layers, and improve the connection reliability between the battery wafer and the conductive connection layer, so as to improve the connection reliability between the two battery wafers electrically connected and fixed based on the conductive connection layer.

[0045] Optionally, an ultraviolet light initiator can be added to the conductive paste for preparing the conductive connection layer, so that the conductive paste can be cured by ultraviolet light irradiation at a low temperature, thereby avoiding problems such as silver paste delamination and high-temperature sintering damage caused by high-temperature welding, so as to form a stable and reliable electrical connection.

[0046] Optionally, the conductive paste can be added with a weather-resistant coupling agent to improve the weather resistance of the conductive connection layer, so as to ensure the performance of the conductive connection layer in complex environments such as high temperature and high humidity.

[0047] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] Refer to Figures 1 - 3 , Figure 1 which is a sectional view of a shingled photovoltaic module provided by the embodiments of the present application, Figure 2 is Figure 1 a top view of a battery wafer in the shingled photovoltaic module shown in Figure 3 is Figure 2 a sectional view along the A-A' direction. Among them, Figure 1It is a sectional view of a shingled photovoltaic module along the length direction of a shingled cell string (i.e., the following first direction F1), and the section is parallel to the thickness direction of the cell 100.

[0049] As Figure 1 and Figure 2 shown, the shingled photovoltaic module includes: at least one shingled cell string, the shingled cell string includes a plurality of cells 100 sequentially connected in a shingled manner along the first direction F1, and the first direction F1 is parallel to the plane where the shingled photovoltaic module is located (let this plane be the first plane S1); the cell 100 includes an overlapping region 101 and a non-overlapping region 102 distributed along the first direction F1; two adjacent cells 100 in the first direction F1 are electrically connected and fixed through a conductive connection layer 103 between the overlapping regions 101; at least one cell 100 has a groove 104 in the overlapping region 101, and the groove 104 is at least used to increase the contact area between the conductive connection layer 103 and the cell 100 in the overlapping region 101.

[0050] Optionally, a groove 104 with a required graphic structure can be formed in the overlapping region 101 by laser etching or other patterning processes, and the specific process means for forming the groove 104 are not limited in the embodiments of the present application.

[0051] The cell 100 can be a main-gridless cell, or a heterojunction cell, or a perovskite cell, or a crystalline silicon cell, etc. The type of the cell 100 is not limited in the embodiments of the present application.

[0052] In the embodiments of the present application, at least one cell 100 is provided with a groove 104 in the overlapping region 101. Based on the groove 104, the contact area between the conductive connection layer 103 and the cell 100 in the overlapping region 101 can be increased. A larger contact area can reduce the contact resistance, and can also improve the adhesion between the film layers, and can improve the connection reliability between the cell 100 and the conductive connection layer 103, so as to improve the connection reliability between the two cells 100 electrically connected and fixed based on the conductive connection layer 103.

[0053] The cell 100 includes opposite first and second surfaces. The first surface includes a positive grid line, and the second surface has a negative grid line. In the same shingled cell string, for two adjacent cells 100 in the first direction F1, in the overlapping region 101, the positive grid line on the first surface of one cell 100 is electrically connected to the negative grid line on the second surface of the other cell 100 through the conductive connection layer 103. In this way, adjacent two cells 100 can realize the connection of the positive and negative grid lines through the conductive connection layer 103 between their relative overlapping regions 101, and each cell 100 in the same shingled cell string can be connected in series only based on the conductive connection layer 103 without additional solder tapes for electrical connection.

[0054] The first surface and / or the second surface has a passivation layer to reduce carrier surface recombination and improve power generation efficiency. Optionally, the passivation layer can be a SiNx thin film, or an AlOx thin film, or a multi-film stack structure of a SiNx thin film and an AlOx thin film.

[0055] In the overlapping region 101, in order to improve the adhesion of the conductive connection layer 103 to the surface of the cell 100, the passivation layer on the surface of the cell 100 can be roughened to increase its surface roughness, thereby improving the adhesion stability of the conductive connection layer 103 on the surface of the overlapping region. Moreover, the roughened surface of the passivation layer can also reduce the reflectivity of light, thereby improving the power generation efficiency of the cell 100. Optionally, the surface roughening of the passivation layer can be achieved by plasma treatment, and a mixed gas of Ar and O2 can be used to form a plasma for plasma treatment of the cell surface.

[0056] For the side surface of the cell 100 provided with the groove 104, the passivation layer on this surface and the side walls and bottom of the groove 104 inside this surface can be simultaneously subjected to plasma treatment, which can enhance the surface roughness of the cell and also enhance the surface activity.

[0057] Based on other embodiments, in one embodiment, as Figure 2 shown, the surface of the cell 100 in the overlapping region 101 has grooves 104 extending in the second direction F2 and grooves 104 extending in the third direction F3. Both the second direction F2 and the third direction F3 are parallel to the plane where the cell 100 is located, so that the grooves 104 extending in the second direction F2 and the grooves 104 extending in the third direction F3 intersect to form a grid structure.

[0058] Forming a grid structure based on the intersecting grooves 104 in the overlapping region 101 of the cell 100 can greatly increase the contact area between the conductive connection layer 103 and the cell 100 in the overlapping region 101, so as to better improve the adhesion between the film layers and greatly reduce the contact resistance.

[0059] Based on other embodiments, in one embodiment, for two adjacent solar cells 100 in the first direction F1, the two solar cells 100 are provided with the same grid structure in the overlapping region 101, and the grid structures on the two solar cells 100 are arranged in a coincident and opposite manner. In this way, in the direction perpendicular to the plane of the photovoltaic module, the grid structures on two adjacent solar cells 100 are vertically overlapped, that is, the vertical projections of the grid structures on two adjacent solar cells 100 on the first plane S1 coincide, and the grooves 104 in two adjacent solar cells 100 are vertically opposite to form a microchannel, which can enable the conductive paste forming the conductive connection layer 103 to flow based on the microchannel during lamination and fixation, so that the conductive paste completely fills the grooves 104, thereby improving the adhesion stability between the conductive connection layer 103 and the solar cell 100 and reducing the connection resistance.

[0060] In the overlapping region 101, the conductive connection layer 103 between two adjacent solar cells 100 includes a full-surface conductive base layer, and the surface of the full-surface conductive base layer has a conductive grid conformal to the grid structure. The grid structure can accommodate more conductive paste to reduce the thickness of the full-surface conductive base layer, thereby reducing the thickness of the shingled photovoltaic module. In addition, the conductive grid filled in the grid structure can ensure the adhesion and electrical connection reliability between the solar cells 100. In particular, the conductive grid can also achieve a good stress buffering effect, disperse the stress between the solar cells 100, and avoid cracks or even fragmentation problems of the solar cells 100 due to stress.

[0061] In one embodiment, as Figure 2 shown, the grid structure includes diamond grid units, one diagonal of the diamond grid unit is parallel to the first direction F1, and the other diagonal of the corresponding diamond grid unit is perpendicular to the first direction F1. In this way, since one diagonal of the diamond grid unit is parallel to the first direction F1 and the other diagonal is perpendicular to the first direction F1, the diamond-shaped conductive grid formed based on the diamond grid unit can buffer stress in its two diagonal directions, release the stress received by the solar cell 100 along the two diagonal directions of the diamond grid unit, better release the stress between the solar cells 100, and better avoid cracks or even fragmentation problems of the solar cells 100 due to stress.

[0062] Referring to Figure 4 , Figure 4 is a schematic diagram of the layout principle of the grid structure with diamond grid units in the solar cell. For the convenience of illustration, Figure 4 only shows one diamond grid unit of each of two adjacent solar cells 100. Among them, Figure 4 the left and right figures in Figure 4The right middle figure is a top view of the diamond grid cells in the two solar cells 100 after being connected in an overlapping region 101 by the shingling method.

[0063] In Figure 4 the shown manner, the diamond grid cells have a first diagonal line L1 and a second diagonal line L2 with different lengths; for two adjacent solar cells 100 in the first direction F1, both of the two solar cells 100 are provided with a grid structure in the overlapping region 101, the centers of the diamond grid cells in the two solar cells 100 are arranged in a relative coincidence manner, the first diagonal line L1 of the diamond grid cell in one solar cell 100 is parallel to the first direction F1, and the second diagonal line L2 of the diamond grid cell in the other solar cell 100 is parallel to the first direction F1. It can be set that the length of the first diagonal line L1 is greater than the length of the second diagonal line L2. When the diamond conductive grid formed based on the grid structure is stressed, it can buffer the stress through micro-deformation, and more stress can be released along the length direction of the first diagonal line L1 with a larger length in the same diamond grid cell.

[0064] In this way, in two adjacent solar cells 100, the first diagonal line L1 of the diamond grid cell of one of them is parallel to the first direction F1, and the first diagonal line L1 of the diamond grid cell of the other is parallel to the fourth direction F4. The fourth direction F4 is perpendicular to the first direction F1 and parallel to the first plane S1, which can enable one solar cell 100 to release stress mainly along the first direction F1 and enable the other solar cell 100 to release stress mainly along the fourth direction F4. The first direction F1 and the fourth direction F4 for releasing stress are orthogonally perpendicular, and the stress between the two solar cells 100 can be released better.

[0065] As Figure 3 shown, the width of the groove 104 increases in the direction from the bottom to the opening of the groove 104 ( Figure 3 the direction from bottom to top in Figure 3 ), and the bottom of the groove 104 is a plane. Compared with a triangular groove (or V-shaped groove),

[0066] Optionally, the groove 104 is as Figure 3The inverted trapezoidal groove shown has an inclination angle β between the side wall and the bottom of the inverted trapezoidal groove of 45° to 75°, for example, this inclination angle β can be 60° ± 5°; the depth of the inverted trapezoidal groove is 20 μm to 50 μm, for example, this depth can be 25 μm to 35 μm, specifically it can be 30 μm; the bottom width of the inverted trapezoidal groove is 40 μm to 50 μm, for example, this width can be 45 μm. When the inverted trapezoidal groove has the above-mentioned value ranges of inclination angle, depth, and bottom width, it can make the conductive paste forming the conductive connection layer 103 completely fill the trench 104.

[0067] The trench 104 with the required graphic structure can be formed on the cutting edge of the battery cell 100 through a laser etching process. The trench 104 with the above size parameters can balance the mechanical interlocking strength of the battery cell 100 in the overlapping area 101 and the processing feasibility of the battery cell 100. If the depth of the trench 104 is too small or the inclination angle β is too small, it will cause the adhesion between the conductive connection layer 103 and the surface of the battery cell to decrease. If the depth of the trench 104 is too large or the inclination angle β is too large, not only will it be easy for air bubbles to appear due to incomplete filling of the conductive paste in the trench 104, but the too-deep trench and the larger inclination angle β can also affect the mechanical strength of the battery cell 100 and increase the risk of brittleness. In the embodiment of the present application, the inverted trapezoidal groove is adopted, which can not only ensure bubble-free filling of the conductive paste in the trench 104 compared with the V-shaped trench, but also provide a basis for the stable surface adhesion between the conductive connection layer 103 formed based on the conductive paste and the surface of the battery cell.

[0068] Reference Figure 5 , Figure 5 is a schematic diagram of the principle of forming a conductive connection layer of a shingled photovoltaic module provided by an embodiment of the present application. On the basis of the above-mentioned implementation manner, the battery cell 100 has a grid structure formed by the trench 104 in the overlapping area 101. The grid structure includes but is not limited to Figure 5 the rhombic grid unit shown. The grid structure can include a rectangular grid unit, a triangular grid unit, a regular pentagonal grid unit, etc. The conductive connection layer 103 is formed by laminating dot-shaped conductive paste at the grid node positions of the grid structure.

[0069] When preparing the shingled photovoltaic module, dot-shaped conductive paste 107 is formed on the surface of the overlapping area 101 of the battery cell 100, and a plurality of dot-shaped conductive paste 107 distributed in a dot matrix are formed on the surface of the overlapping area 101. Optionally, as Figure 5 shown, a dot-shaped conductive paste 107 can be formed on each grid node of the grid structure respectively, or a dot-shaped conductive paste 107 can be formed on some grid nodes of the grid structure respectively. When the overlapping areas 101 of two battery cells 100 are pressed together relatively, the conductive paste of the dot-shaped conductive paste 107 can flow along the trench 104 at the grid node, and can better fill the trench 104.

[0070] Optionally, the diameter of the dot-shaped conductive paste 107 may be 150 μm to 250 μm, for example, it may be 200 μm. Multiple dot-shaped conductive pastes 107 distributed in a dot matrix can be formed on the surface of the overlapping area 101 through a precision screen printing process.

[0071] When the grid structure includes diamond grid units, the diagonal length of the diamond grid unit may be 0.6 mm to 1.0 mm, for example, it may be 0.8 mm. The two diagonal lengths of the diamond grid unit may be equal, for example, both diagonals may be 0.8 mm, so that the distance between two adjacent dot-shaped conductive pastes 107 can be 0.8 mm. In other ways, the two diagonal lengths of the diamond grid unit may also be unequal.

[0072] Such as Figure 5 As shown, based on the grid structure formed by the trench 104 in the embodiment of the present application, multiple dot-shaped conductive pastes 107 arranged in a dot matrix can be formed on the surface of the battery chip through the conductive paste, and a conductive connection layer 103 can be formed by lamination in subsequent process steps based on the multiple dot-shaped conductive pastes 107. In the embodiment of the present application, based on the adapted grid structure and the conductive paste, innovation can be made in the interconnection method of the battery chip 100 as Figure 5 shown. When coating the conductive paste, it is not necessary to coat the entire surface or perform continuous linear coating like conventional silver paste. Instead, multiple discontinuous dot-shaped conductive pastes 107 can be formed as Figure 5 shown. By precisely controlling the size of the dot-shaped conductive paste 107 in the dot matrix and the size of the diamond grid unit in the grid structure, while ensuring the conductive performance, the consumption of the conductive paste can be reduced by 40%. Additionally, through the dot-shaped conductive pastes 107 distributed in a dot matrix, the shrinkage stress during the lamination process can be effectively buffered, and crack generation can be inhibited.

[0073] Moreover, the conduction path between the battery chips 100 can be realized through a cold pressing bonding process, and combined with the electron tunneling effect of graphene and / or carbon nanotubes in the conductive paste, excellent electrical connection reliability can be ensured.

[0074] Refer to Figure 6 , Figure 6 which is a cross-sectional view of another overlapping tile photovoltaic module provided by the embodiment of the present application. On the basis of other embodiments, Figure 6 the overlapping tile photovoltaic module shown also includes a backplane 105. The overlapping tile battery string is adhesively fixed on the surface of the backplane 105 through an adhesive layer 106.

[0075] In Figure 1 and Figure 6 shown ways, the planes where each battery chip 100 is located are parallel, and all are parallel to the first plane S1. In the same overlapping tile battery string, each battery chip 100 forms a vertical step structure.

[0076] Reference Figure 7 , Figure 7 is a sectional view of another overlapping photovoltaic module provided by an embodiment of the present application. On the basis of other embodiments, Figure 7 in the overlapping photovoltaic module shown, the planes where each cell 100 is located are all parallel and have the same included angle with the first plane S1.

[0077] As described above, the conductive connection layer 103 is prepared from a conductive paste. The conductive paste for preparing the conductive connection layer includes a uniformly mixed conductive component, KH-500 silane coupling agent, and a UV initiator; wherein, the conductive component includes silver powder and also includes graphene and / or carbon nanotubes. Optionally, the conductive component includes silver powder, graphene, and carbon nanotubes at the same time. The material properties of the conductive paste of this component can better adapt to the trapezoidal groove, not only can better fill the groove 104, but also can make the conductive connection layer 103 have a lower connection resistance and weather resistance.

[0078] Since the conductive component includes silver powder and also includes graphene and / or carbon nanotubes, and both graphene and carbon nanotubes are good conductive materials, the conductivity of the conductive paste can be improved. Therefore, while reducing the content of precious metal silver, the conductivity of the conductive paste can be ensured. Moreover, compared with the powdery silver powder, graphene and carbon nanotubes also have a larger two-dimensional size, which can improve the toughness of the conductive connection layer 103, and can also form a three-dimensional conductive network after uniform mixing and curing to form better conductivity and improve the electrical connection reliability between the cells 100.

[0079] Optionally, in the conductive paste, the silver powder content is 50wt% - 60wt%, such as 55wt%; the graphene content is 1wt% - 3wt%, such as 2wt%; the carbon nanotube content is 0.5wt% - 2wt%, such as 1wt%. In a conventional silver paste, the silver powder content is relatively high (the silver powder content exceeds 80wt%). In the embodiment of the present application, the conductive component can make the conductive connection layer 103 have good conductivity and can reduce the content of silver powder, forming a conductive paste with a low silver content.

[0080] Optionally, in the conductive paste, the content of KH-500 silane coupling agent is 0.5 wt% - 1.5 wt%, for example, it can be 1 wt%. The KH-500 silane coupling agent in the conductive paste can be used as a modifying substance. The modifying substance in the conductive paste can improve the adhesion between the conductive connection layer 103 and the passivation layer to ≥5 N / mm through chemical bonding. Specifically, the silicon alkyl group in the KH-550 silane coupling agent can react with active groups such as hydroxyl groups on the surface of the passivation layer to form a stable chemical bond. This chemical bonding not only enhances the adhesion between the conductive connection layer 103 and the passivation layer, but also improves the weather resistance and chemical stability of the conductive connection layer 103, enabling the conductive connection layer 103 to maintain excellent electrical conductivity and mechanical strength during long-term use.

[0081] In the overlapping shingle photovoltaic module conventionally connected by solder tapes, when tested at high temperature and high humidity (84°C / 85% RH), after 1000 hours, the resistivity of the connection resistance between the cells increases by 30%, and the adhesion between the solder tape and the surface passivation layer of the cell is less than 3 N / mm, which is prone to the problem of cell interconnection failure.

[0082] In the embodiment of the present application, two adjacent cells 100 are directly electrically connected and fixed through the conductive connection layer 103 formed by the conductive paste between the overlapping regions 101. The conductive connection layer formed by the conductive paste has good weather resistance and good reliability and stability in a high temperature and high humidity environment. Moreover, the KH-500 silane coupling agent in the conductive paste can improve the adhesion between the conductive connection layer 103 and the surface passivation layer of the cell through chemical bonding. Experimental data show that the adhesion between the conductive connection layer 103 and the passivation layer can be increased to 5 N / mm. Therefore, the conductive connection layer 103 formed based on the conductive paste provided in the embodiment of the present application can greatly improve the weather resistance in a high temperature and high humidity environment, the resistivity is relatively stable after long-term use, and the problem of cell interconnection failure can be effectively avoided.

[0083] In the overlapping shingle photovoltaic module conventionally connected by solder tapes, the series connection between the cells needs to be achieved through a welding process, and the welding temperature generally exceeds 200°C. However, the thickness of the cell 100 is relatively thin. Taking a thin silicon solar cell as an example, the high welding temperature will cause the fragmentation rate of the cell to exceed 20%, which greatly affects the yield. Moreover, welding makes the module preparation process complex. The welding of all cells in a single module takes more than 10 minutes, resulting in low production efficiency and high manufacturing cost.

[0084] In the shingled photovoltaic module provided by the embodiment of the present application, a conductive connection layer can be directly prepared by conductive paste. The conductive paste can be directly cured by low-temperature light irradiation without a high-temperature welding process, thus avoiding the chip-breaking problem caused by high-temperature welding and improving the product yield. Moreover, compared with the conventional process that requires welding each cell one by one, the low-temperature light-curing process can simultaneously perform low-temperature light curing on the conductive paste in the entire shingled cell string or the entire photovoltaic module, making the module preparation process simple, improving the production efficiency, and reducing the manufacturing cost.

[0085] For a shingled photovoltaic module that uses conventional silver paste for connection between cells, in order to ensure the adhesion between cells, a large amount of silver paste is required, and the silver paste consumption exceeds 20 mg / cell, resulting in a high cost. Moreover, the interconnection resistance of the conventional silver paste exceeds 0.5 mΩ•cm², the CTM loss of the module output power exceeds 3%, and there are problems such as silver paste cracking and silver paste layer failure caused by stress concentration at the shingled edge.

[0086] In the shingled photovoltaic module provided by the embodiment of the present application, a groove 104 is provided in the overlapping region 101. The conductive connection layer 103 not only includes a whole-surface conductive base layer between the opposite surfaces of two cells, but also includes a conductive grid in the groove 104. Based on the conductive grid, the conductivity of the conductive connection layer 103 and the adhesion to the two cells 100 can be effectively ensured, thereby effectively reducing the thickness of the whole-surface conductive base layer, reducing the consumption of conductive paste, and reducing the manufacturing cost. By adding graphene and / or carbon nanotubes to the conductive component to enhance conductivity and cooperating with the groove 104 in the overlapping region 101, the consumption of the conductive paste between two adjacent cells 100 in the overlapping region 101 can be greatly reduced. The consumption of the conductive paste can be reduced to 12 mg / cell, and the material cost is reduced to 40%.

[0087] Moreover, the present application uses a new type of conductive paste to prepare the conductive connection layer 103. The conductive component in the conductive paste includes not only silver powder but also graphene and / or carbon nanotubes. Graphene and carbon nanotubes have excellent conductivity and large two-dimensional sizes. After the conductive paste is cured into the conductive connection layer 103, a three-dimensional conductive network can be formed in the conductive connection layer, effectively reducing the interconnection resistance between cells and reducing the loss of the output power CTM. Moreover, since graphene and carbon nanotubes have larger two-dimensional sizes and greater toughness than silver powder and also have a stress buffering effect, the toughness of the conductive connection layer 103 can be improved, effectively preventing the conductive connection layer 103 from cracking and the problem of failure of the conductive connection layer 103 caused by stress concentration at the shingled edge.

[0088] Since the conductive paste includes a UV initiator, the conductive paste can be cured at low temperature by UV light irradiation. It can be rapidly cured in 5 minutes under the low temperature condition of 80°C to 120°C, effectively solving the problems such as easy delamination and high-temperature sintering damage of traditional silver paste, and providing a reliable interconnection material guarantee for the shingled photovoltaic module. While the conventional silver paste sintering takes 30 minutes, the present application can increase the production efficiency by 6 times, greatly simplify the process flow, and reduce the equipment and labor costs.

[0089] Optionally, 365 nm UV light (150 Mw / cm 2 ) can be used for low-temperature light curing. The UV initiator in the conductive paste can be the TPO-L UV initiator, which can enable the conductive paste to achieve rapid curing below 80°C within 5 minutes, completely breaking through the technical limitation that traditional silver paste must rely on high-temperature sintering above 200°C. The TPO-L UV initiator can synergistically act with the KH-550 silane coupling agent, effectively solving the problem of poor compatibility between ordinary UV-curable materials and silver powder, while ensuring the interfacial bonding strength, completely avoiding the risk of thermal damage to temperature-sensitive batteries such as heterojunction / perovskite at high temperatures.

[0090] When forming the conductive connection layer 103 based on the conductive paste provided by the embodiments of the present application, the connection and fixation between the battery chips 100 can be achieved through a cold pressing bonding process. The densification connection of the silver powder particles in the conductive paste can be realized under the precise pressure of 5 - 10 MPa, and at the same time, the three-dimensional conductive network of activated carbon nanotubes / graphene in the conductive paste is activated. This process can make full use of the self-aligning structure design of the trapezoidal groove at the edge of the battery chip, improving the shingled alignment accuracy to ±20 μm (±100 μm for the traditional process). Not only can the fragment rate be controlled below 5%, but also the interconnection resistivity can be significantly reduced from the traditional 0.5 mΩ•cm² to 0.2 mΩ•cm². The whole set of preparation process of the shingled photovoltaic module can achieve an efficient and low-temperature interconnection solution through roll-to-roll pre-coating of the conductive paste and precise cold pressing, providing a perfect solution for the reliable connection of ultra-thin batteries with a thickness of no more than 80 μm. Moreover, the roll-to-roll pre-coating of the conductive paste process is convenient for realizing the automated and continuous production of the shingled photovoltaic module, meeting the requirements of modern industrial production.

[0091] In the overlapping shingle PV module provided by the embodiments of the present application, specific grooves 104 are formed in the overlapping area, innovating in the structure of the cell 100; a novel conductive paste for preparing the conductive connection layer 103 is provided, innovating in the material of the cell 100; based on the structure of the grooves 104, dot-shaped conductive pastes 107 arranged in a lattice can be formed by the above-mentioned conductive paste to form the required conductive connection layer 103, innovating in the preparation process of the overlapping shingle PV module. Based on these innovations, the weather resistance of the overlapping shingle PV module can be improved, the problem of welding damage can be avoided, the amount of conductive paste used can be reduced, the connection resistance loss can be reduced, the production efficiency and product yield can be improved, and the performance bottleneck of the module can be broken through.

[0092] Based on the overlapping shingle PV module provided by the above embodiments, another embodiment of the present application further provides a method for preparing an overlapping shingle PV module. This preparation method is used to prepare the overlapping shingle PV module provided by any one of the above embodiments, and this preparation method can be as Figure 8 shown.

[0093] Referring to Figure 8 , Figure 8 which is a schematic flow chart of a method for preparing an overlapping shingle PV module provided by an embodiment of the present application. This preparation method includes:

[0094] Step S11: Provide a cell 100, which includes an overlapping area 101 and a non-overlapping area 102 distributed along a first direction F1; the first direction F1 is parallel to the plane where the overlapping shingle PV module is located.

[0095] Step S12: Connect a plurality of cells 100 in a shingle manner along the first direction F1 in sequence to form a shingle cell string; two adjacent cells 100 in the first direction F1 are electrically connected and fixed through a conductive connection layer 103 between the overlapping areas 101;

[0096] wherein, at least one cell 100 has grooves 104 in the overlapping area 101, and the grooves 104 are at least used to increase the contact area between the conductive connection layer 103 and the cell 100 in the overlapping area 101.

[0097] After the grooves 104 are formed, the surface of the cell 100 can be subjected to plasma treatment to increase the roughness of the passivation layer on the cell surface and the inner wall of the grooves 104 inside the cell surface, and the surface activity can also be increased to facilitate improving the adhesion of the subsequently formed conductive connection layer 103 on the cell surface.

[0098] As described above, the conductive connection layer 103 is prepared based on the conductive paste. The conductive paste includes graphene and / or carbon nanotubes to enhance the conductive performance and reduce the silver powder content. Equivalent to 80% of the silver content in the conventional silver paste, in this application, the silver powder content can be reduced to 55%, and the material cost can be reduced by 40%.

[0099] Moreover, the conductive paste also includes KH-500 silane coupling agent and ultraviolet light initiator, which can solve the adhesion problem between the conductive paste and the passivation layer. Based on the ultraviolet light initiator, low-temperature light curing at 80°C to 120°C can be achieved, avoiding damage to the performance of the battery chip caused by high-temperature welding (greater than 20°C), and being applicable to temperature-sensitive battery chips; based on the KH-500 silane coupling agent, the adhesion of the conductive connection layer 103 can be increased to ≥5 N / mm, and the increase in resistivity after aging test is only 8%, which is much better than the traditional process. In addition, the preparation method provided by the embodiments of this application can adopt the roll-to-roll pre-coated conductive paste process to replace single-piece printing, and cooperate with cold pressing bonding and self-aligning structure to achieve low-energy consumption, high-precision, and continuous production.

[0100] Based on the grooves 104 in the overlapping region 101 and the plasma treatment on the surface of the battery chip, adjacent two battery chips 100 can form a mechanical locking structure through the conductive connection layer 103 in the overlapping region, enhancing the connection strength.

[0101] The conductive connection layer 103 can be formed by the above-mentioned conductive paste. The conductive paste does not need to be printed in a continuous line. Multiple dot-shaped conductive pastes arranged in a dot matrix can be formed based on the dots of the grid structure, and the conductive connection layer 103 is formed by laminating non-continuous multiple dot-shaped conductive pastes.

[0102] In the description of this application, the embodiments in the specification are described in a progressive, or parallel, or a combination of progressive and parallel ways. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. The embodiments provided by the embodiments of this application can be combined with each other without contradiction.

[0103] It should be noted that in the description of this application, it should be understood that the descriptions of the drawings and embodiments are illustrative rather than restrictive. The same reference numerals throughout the embodiments of the specification identify the same structures. In addition, for the sake of understanding and easy description, the drawings may exaggerate the thickness of some layers, films, panels, regions, etc. At the same time, it can be understood that when an element such as a layer, film, region, or substrate is referred to as "on" another element, the element can be directly on the other element or there may be an intermediate element. In addition, "on..." means positioning the element on or below another element, but essentially does not mean positioning on the upper side of another element according to the direction of gravity.

[0104] The orientation or positional relationship indicated by terms such as "upper", "lower", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component present at the same time.

[0105] It should also be noted that in this text, relative terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that an article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the article or device comprising the above elements.

[0106] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A shingled photovoltaic module, characterized in that, Comprising: At least one shingled battery string, the shingled battery string comprising a plurality of solar cells sequentially connected in a shingled manner along a first direction, the first direction being parallel to the plane of the shingled photovoltaic module; the solar cells comprising an overlapping region and a non-overlapping region distributed along the first direction; two adjacent solar cells in the first direction being electrically connected and fixed through a conductive connection layer between the overlapping regions; At least one of the solar cells has a groove in the overlapping region, the groove being at least for increasing the contact area between the conductive connection layer and the solar cell in the overlapping region.

2. The overlapping tile photovoltaic module according to claim 1, wherein The width of the groove increases in the direction from the bottom to the opening of the groove, and the bottom of the groove is a plane.

3. The overlapping photovoltaic module according to claim 2, wherein The groove is an inverted trapezoidal groove, the inclination angle between the side wall and the bottom of the inverted trapezoidal groove is 45° - 75°, the depth of the inverted trapezoidal groove is 20μm - 50μm, and the bottom width of the inverted trapezoidal groove is 40μm - 50μm.

4. The overlapping photovoltaic module according to claim 1, characterized in that, The surface of the solar cell in the overlapping region has grooves extending along a second direction and grooves extending along a third direction, the second direction and the third direction both being parallel to the plane of the solar cell, so that the grooves extending along the second direction and the grooves extending along the third direction intersect to form a grid structure.

5. The overlapping photovoltaic module according to claim 4, wherein, For two adjacent solar cells in the first direction, the two solar cells are provided with the same grid structure in the overlapping region, and the grid structures on the two solar cells are arranged in a coincident and opposite manner.

6. The overlapping photovoltaic module according to claim 4, characterized in that, The grid structure comprises diamond grid units, and one diagonal of the diamond grid unit is parallel to the first direction.

7. The overlapping photovoltaic module according to claim 6, wherein The diamond grid unit has a first diagonal and a second diagonal with different lengths; For two adjacent solar cells in the first direction, the two solar cells are both provided with the grid structure in the overlapping region, the centers of the diamond grid units in the two solar cells are arranged in a coincident and opposite manner, the first diagonal of the diamond grid unit in one solar cell is parallel to the first direction, and the second diagonal of the diamond grid unit in the other solar cell is parallel to the first direction.

8. The overlapping photovoltaic module according to claim 1, characterized in that, The conductive paste for preparing the conductive connection layer comprises a uniformly mixed conductive component, KH-500 silane coupling agent and a UV initiator; Wherein, the conductive component comprises silver powder and further comprises graphene and / or carbon nanotubes.

9. The overlapping photovoltaic module according to any one of claims 1-8, characterized in that, The solar cell has a grid structure formed by the grooves in the overlapping region; The conductive connection layer is formed by laminating dot-shaped conductive paste located at the grid node positions of the grid structure.

10. A method for preparing an overlapping photovoltaic module according to any one of claims 1-9, characterized in that, The preparation method comprises: Providing solar cells, the solar cells comprising an overlapping region and a non-overlapping region distributed along the first direction; the first direction being parallel to the plane of the shingled photovoltaic module; Sequentially connecting a plurality of the solar cells in a shingled manner along the first direction to form a shingled battery string; two adjacent solar cells in the first direction being electrically connected and fixed through a conductive connection layer between the overlapping regions; Wherein, at least one of the cell wafers has a groove in the overlapping region, and the groove is at least used to increase the contact area between the conductive connection layer and the cell wafer in the overlapping region.

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