A back contact photovoltaic module, a printing plate and a back contact solar stack module

Abstract

The application relates to the technical field of photovoltaic cells, in particular to a back contact photovoltaic module, a conductive glue printing screen and a back contact solar laminated module. The back contact photovoltaic module comprises at least two cell pieces connected in layers, and the cell pieces in adjacent layers are electrically connected through conductive glue. In the two cell pieces in adjacent layers, the positive current output part of one cell piece is connected with one end of the conductive glue, and the negative current output part of the other cell piece is connected with the other end of the conductive glue. In the thickness direction of the back contact photovoltaic module, the conductive glue covers part of the surface of the two cell pieces in adjacent layers, and the bottom of the conductive glue is in a stepped shape. The application electrically connects the two cell pieces in adjacent layers through the conductive glue, the conductive glue can be printed by the conductive glue printing screen at one time, the production efficiency and the yield of the tile structure formed by the two cell pieces in adjacent layers are improved, and the production cost is reduced. The conductive glue is soft and has good adhesion, and can be closely attached to the two cell pieces in adjacent layers.

Description

Technical Field

[0001] This application relates to the field of back-contact battery technology, and in particular to a back-contact photovoltaic module, a printing screen, and a back-contact solar tandem module. Background Technology

[0002] The positive and negative grid lines of the back contact solar cell are located on the back side. When multiple back contact solar cells are connected in a shingled manner, adjacent solar cells need to be connected with the same solder strip. However, the production efficiency of this structure is relatively low. Summary of the Invention

[0003] This application provides a back-contact photovoltaic module, a printing screen, and a back-contact solar tandem module, aiming to improve the production efficiency and yield of back-contact photovoltaic modules.

[0004] This application provides a back-contact photovoltaic module in a first aspect, the back-contact photovoltaic module comprising at least two stacked solar cells, the adjacent stacked solar cells being electrically connected by conductive adhesive;

[0005] In two adjacent stacked battery cells, the positive current output section of one battery cell is connected to one end of the conductive adhesive, and the negative current output section of the other battery cell is connected to the other end of the conductive adhesive.

[0006] Along the thickness direction of the back-contact photovoltaic module, the conductive adhesive covers a portion of the surface of two adjacent stacked solar cells, and the bottom of the conductive adhesive is stepped.

[0007] In one possible design, the back of the solar cell is provided with a fine grid and a main grid, the main grid being connected to the fine grid to collect the current collected by the fine grid;

[0008] Along the stacking direction of the solar cells, the two ends of the conductive adhesive are electrically connected to the main grids of two adjacent stacked solar cells with opposite polarities.

[0009] In one possible design, the back of the solar cell is provided with a fine grid and solder ribbons, the solder ribbons being connected to the fine grids to collect the current collected by the fine grids;

[0010] The back of the battery cell is also provided with an edge connecting line, one end of which is connected to the solder strip, and the other end can extend to the edge of the battery cell.

[0011] In two adjacent stacked battery cells, the edge connection line on one battery cell is a positive current output section, and the edge connection line on the other battery cell is a negative current output section.

[0012] Along the stacking direction of the battery cells, the two ends of the conductive adhesive are electrically connected to the two edge connection lines of the adjacent stack.

[0013] In one possible design, in each of the solar cells, one end of each of the conductive adhesives can only be connected to the grid connected to the positive current output section or the negative current output section.

[0014] In one possible design, the length of the conductive adhesive is L1 along the stacking direction of adjacent solar cells, where 0.5mm≤L1≤8mm;

[0015] Along a direction perpendicular to the stacking direction of adjacent battery cells, the width of the conductive adhesive is L2, 0.2mm≤L2≤5mm.

[0016] In a second aspect, this application provides a printing screen with a plurality of uniformly arranged printing mesh holes, the bottom of which is stepped.

[0017] In one possible design, the printing mesh is provided with a first adhesive groove, a second adhesive groove, and an adhesive channel that are connected to each other.

[0018] The first glue tank and the second glue tank are stepped, and the printing channel is located above the first glue tank and the second glue tank.

[0019] In one possible design, along the thickness direction of the printing screen, the projection surface of the printing channel can cover at least a portion of the projection surface of the first adhesive groove and at least a portion of the projection surface of the second adhesive groove.

[0020] In one possible design, the printing screen is provided with a first abutting surface and a second abutting surface, the first abutting surface being used to connect with one of the adjacent stacked battery cells, and the second abutting surface being used to connect with the other of the adjacent stacked battery cells.

[0021] The first abutting surface and the second abutting surface are connected to form a stepped surface.

[0022] This application provides a back-contact solar tandem module in a third aspect, the back-contact solar tandem module including a top cell, an intermediate connecting layer and a bottom cell, the intermediate connecting layer being connected between the top cell and the bottom cell;

[0023] The top cell is one of a perovskite cell, a cadmium telluride solar cell, a copper indium gallium selenide solar cell, or a gallium arsenide solar cell, and the bottom cell is the back-contact photovoltaic module described above.

[0024] The beneficial effects of this application embodiment are as follows: This application embodiment uses conductive adhesive to electrically connect two adjacent stacked battery cells. The conductive adhesive can be printed in one go by a printing screen, which helps to improve the production efficiency and yield of forming a shingled structure between two adjacent battery cells and reduce production costs.

[0025] In addition, the conductive adhesive is soft and has good adhesion, allowing it to adhere tightly to two adjacent stacked solar cells. The conductive adhesive also exhibits high strength, tensile strength, and fatigue resistance, ensuring the stability of the connection between two adjacent stacked solar cells.

[0026] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the photovoltaic module provided in this application;

[0028] Figure 2 A top view of the shingled connection of adjacent solar cells (with main busbars) provided in this application;

[0029] Figure 3 A top view of the shingled connection of adjacent solar cells (without main busbars) provided in this application;

[0030] Figure 4 for Figure 3 Schematic diagram of the middle section;

[0031] Figure 5 A side view of the shingled connection of adjacent solar cells provided in this application;

[0032] Figure 6 A side view of the shingled connection of adjacent solar cells provided in this application;

[0033] Figure 7 A top view of the printing screen provided in this application;

[0034] Figure 8 A side view of a portion of the structure of the printing screen provided in this application;

[0035] Figure 9 A side view of the printing screen and the battery cell provided in this application;

[0036] Figure 10 A side view of the printing screen and the battery cell provided in this application;

[0037] Figure 11 Side view of the printing screen, battery cells and assembly platform provided in this application.

[0038] Figure label:

[0039] 100-back contact photovoltaic module;

[0040] 101 - First cover plate;

[0041] 102 - First adhesive film;

[0042] 103 - Battery string assembly;

[0043] 104 - Second film;

[0044] 105 - Second cover plate;

[0045] 10-cell battery;

[0046] 10a - First solar cell;

[0047] 10b - Second solar cell;

[0048] 11a - Positive current output section;

[0049] 11b - Negative current output section;

[0050] 111-Fine grid;

[0051] 112 - Main gate;

[0052] 113 - Edge connection line;

[0053] 20-Conductive adhesive;

[0054] 21-Part One;

[0055] 22 - Part Two;

[0056] 30-Printing screen;

[0057] 31 - Printing mesh;

[0058] 311 - First glue tank;

[0059] 312 - Second glue tank;

[0060] 313 - Printing Passage;

[0061] 32 - First contact surface;

[0062] 33 - Second contact surface;

[0063] 40 - Assembly platform.

[0064] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation

[0065] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0066] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0067] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0068] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0069] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when referring to an element being connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected through an intermediate element.

[0070] In the field of photovoltaic power generation technology, the back-contact photovoltaic module 100 is the core component that converts solar energy into electrical energy. Figure 1 This is a schematic diagram of the structure of a back-contact photovoltaic module 100. The back-contact photovoltaic module 100 includes a first cover plate 101, a first encapsulant film 102, a battery string group 103, a second encapsulant film 104, and a second cover plate 105 stacked along its own thickness direction Z. The first cover plate 101 and the battery string group 103 are sealed and fixed together by the first encapsulant film 102, and the second cover plate 105 and the battery string group 103 are sealed and fixed together by the second encapsulant film 104.

[0071] Specifically, the first cover plate 101 and / or the second cover plate 105 can be photovoltaic glass with high light transmittance, such as double-coated glass. The first cover plate 101 and the second cover plate 105 are used to protect the internal encapsulation materials and battery strings from mechanical damage and external environmental corrosion, and have waterproof and moisture-proof capabilities. During the lamination process of the back-contact photovoltaic module 100, the first encapsulant film 102 and the second encapsulant film 104 are used to encapsulate the battery string group 103, preventing the external environment from affecting the performance of the battery string group 103, and at the same time, they can also bond the first cover plate 101, the battery string group 103 and the second cover plate 105 into a whole.

[0072] The battery string group 103 can be one or more. If there are multiple battery string groups 103, they can be connected in series, in parallel, or in a mixed configuration. A mixed configuration means that multiple battery string groups 103 are connected in both series and parallel, which can provide higher voltage and capacity. One end of the busbar is connected to the battery string group 103, and the other end is connected to the junction box to lead out the electrical energy generated by the back-contact photovoltaic module 100 and connect it to an external load.

[0073] The materials of the first film 102 and the second film 104 can be one of the following: ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), polyvinyl butyral (PVB), etc., or they can be EPE film (EVA-POE-EVA co-extrusion structure) or EP film (EVA-POE co-extrusion structure).

[0074] It is understood that other layers may be provided between the first cover plate 101 and the first adhesive film 102, between the first adhesive film 102 and the battery string group 103, between the battery string group 103 and the second adhesive film 104, and between the second adhesive film 104 and the second cover plate 105. The specific number of layers for the back contact photovoltaic module 100 can be set according to the actual situation, and this embodiment does not limit it.

[0075] In this embodiment, the back-contact photovoltaic module 100 connects individual solar cells in series and parallel, encapsulates them, and connects them with external wires, thus becoming a solar cell module that can be used independently as a photovoltaic power source. The back-contact photovoltaic module 100 absorbs sunlight and directly converts solar radiation energy into the required electrical energy output using the photovoltaic effect.

[0076] Figure 2This is a schematic diagram of a partial structure showing the stacked connection of adjacent solar cells 10. The adjacent stacked solar cells 10 are electrically connected by conductive adhesive 20. In the two adjacent stacked solar cells 10, along the thickness direction Z of the back-contact photovoltaic module 100, the conductive adhesive 20 can cover part of the surface of the two adjacent stacked solar cells 10, so that the positive current output part 11a of one solar cell 10 is connected to one end of the conductive adhesive 20, and the negative current output part 11b of the other solar cell 10 is connected to the other end of the conductive adhesive 20, thereby realizing the electrical connection of the two adjacent stacked solar cells 10 by the conductive adhesive 20.

[0077] For example, two adjacent stacked battery cells 10 are a first battery cell 10a and a second battery cell 10b. The edge of the first battery cell 10a overlaps the edge of the second battery cell 10b, so that the positive current output part 11a of the first battery cell 10a and the negative current output part 11b of the second battery cell 10b are close to each other. One end of the conductive adhesive 20 can cover part of the positive current output part 11a of the first battery cell 10a, and the other end of the conductive adhesive 20 can cover part of the negative current output part 11b of the second battery cell 10b. The two ends of the conductive adhesive 20 are connected to the positive current output part 11a of the first battery cell 10a and the negative current output part 11b of the second battery cell 10b, respectively. The conductive adhesive 20 electrically connects the adjacent stacked first battery cell 10a and the second battery cell 10b, thereby realizing the electrical connection between the first battery cell 10a and the second battery cell 10b, and thus realizing the series connection between the first battery cell 10a and the second battery cell 10b.

[0078] In this embodiment, conductive adhesive 20 is used to electrically connect two adjacent stacked battery cells 10. The conductive adhesive 20 can be printed in one go by printing screen 30, which helps to improve the production efficiency and yield of forming a shingled structure between two adjacent battery cells 10 and reduce production costs.

[0079] In addition, the conductive adhesive 20 is soft and has good adhesion, enabling it to adhere tightly to two adjacent stacked solar cells 10. The conductive adhesive 20 also has high strength, tensile strength, and fatigue resistance, ensuring the stability of the connection between the two adjacent stacked solar cells 10.

[0080] In some embodiments, the solar cell 10 may be a solar cell with a main grid, or the solar cell 10 may be a solar cell without a main grid.

[0081] Specifically, in one embodiment, please refer to [link / reference needed]. Figure 2 When the solar cell 10 is a solar cell with a main grid, a fine grid 111 and a main grid 112 are provided on the back side of the solar cell 10. The fine grid 111 is used to collect photogenerated carriers, and the main grid 112 is used to collect the current of the fine grid 111. The main grid 112 is connected to the fine grid 111 to collect the current collected by the fine grid 111.

[0082] Please continue to refer to this. Figure 2 Along the stacking direction X of the solar cells 10, the two ends of the conductive adhesive 20 are electrically connected to the main grids 112 of opposite polarity in the two adjacent solar cells 10. That is, in the two main grids 112 of opposite polarity in the two adjacent solar cells 10, one main grid 112 is the positive current output section 11a mentioned above, and the other main grid 112 is the negative current output section 11b mentioned above.

[0083] For example, two adjacent stacked battery cells 10 are a first battery cell 10a and a second battery cell 10b. Both the first battery cell 10a and the second battery cell 10b have multiple positive electrode grids, multiple negative electrode grids, multiple positive electrode main grids, and multiple negative electrode main grids on their back surfaces. The multiple positive electrode grids and multiple negative electrode grids are alternately distributed along the stacking direction X of the battery cells 10 and extend along a direction Y perpendicular to the stacking direction of the battery cells 10. The multiple positive electrode main grids and multiple negative electrode main grids are also alternately distributed along a direction Y perpendicular to the stacking direction of the battery cells 10 and extend along the stacking direction X of the battery cells 10. The positive electrode main grids are connected to the positive electrode grids, and the negative electrode main grids are connected to the negative electrode grids.

[0084] When the first battery cell 10a and the second battery cell 10b are stacked, the positive main grid of the first battery cell 10a and the negative main grid of the second battery cell 10b are positioned opposite each other. One end of the conductive adhesive 20 can cover part of the positive main grid of the first battery cell 10a, and the other end of the conductive adhesive 20 can cover part of the negative main grid of the second battery cell 10b. This allows the conductive adhesive 20 to connect the positive main grid of the first battery cell 10a and the negative main grid of the second battery cell 10b, thereby connecting the positive and negative electrodes of the two adjacent stacked battery cells 10 in sequence, adding the voltage and power, and improving the overall performance.

[0085] Similarly, at this time, the negative main grid of the first battery cell 10a and the positive main grid of the second battery cell 10b are arranged opposite each other, one end of the conductive adhesive 20 is connected to the negative main grid of the first battery cell 10a, and the other end of the conductive adhesive 20 is connected to the positive main grid of the second battery cell 10b.

[0086] Figure 3 This is a schematic diagram of a partial structure of adjacent battery cells 10 stacked together. In another embodiment, when the battery cell 10 is a gridless battery cell 10, a fine grid 111 and a solder ribbon are provided on the back side of the battery cell 10. The fine grid 111 is used to collect photogenerated carriers, and the solder ribbon is connected to the fine grid 111 to collect the current collected by the fine grid 111.

[0087] For example, two adjacent stacked battery cells 10 are a first battery cell 10a and a second battery cell 10b. Both the first battery cell 10a and the second battery cell 10b have multiple positive electrode grids, multiple negative electrode grids, and multiple solder ribbons on their back surfaces. The multiple positive electrode grids and multiple negative electrode grids are alternately distributed along the stacking direction X of the battery cells 10 and extend along a direction Y perpendicular to the stacking direction of the battery cells 10. The multiple solder ribbons are also alternately distributed along a direction Y perpendicular to the stacking direction of the battery cells 10 and extend along the stacking direction X of the battery cells 10. Among adjacent solder ribbons, one solder ribbon is connected to the positive electrode grid, and the other solder ribbon is connected to the negative electrode grid.

[0088] Please continue to refer to this. Figure 3 The back of the battery cell 10 is also provided with an edge connecting line 113. One end of the edge connecting line 113 is connected to the solder strip, and the other end can extend to the edge of the battery cell 10. That is, among adjacent edge connecting lines 113, one edge connecting line 113 is connected to the positive electrode grid through the solder strip, making the edge connecting line 113 a positive electrode edge connecting line, and the other edge connecting line 113 is connected to the negative electrode grid, making the edge connecting line 113 a negative electrode edge connecting line.

[0089] It should be noted that the edge connection line 113 is a wire located at the edge of the solar cell 10, used to collect the current from the fine grid 111 at the edge of the solar cell. In gridless solar cells, the solder ribbons are all positioned at a certain distance from the edge of the solar cell to prevent microcracks at the edge of the cell caused by the strength of the solder ribbons during packaging. By setting the edge connection line 113 at the edge of the solar cell 10, the collection of edge current of the solar cell 10 is ensured.

[0090] Please continue to refer to this. Figure 3 Along the stacking direction X of the battery cell 10, the two ends of the conductive adhesive 20 are electrically connected to the two edge connection lines 113 of the adjacent stack. That is, in the two adjacent stacked battery cells 10, the edge connection line 113 on one battery cell 10 is the positive current output section 11a, and the edge connection line 113 on the other battery cell 10 is the negative current output section 11b.

[0091] In other words, when the first battery cell 10a and the second battery cell 10b are stacked, the positive electrode edge connection line of the first battery cell 10a is positioned opposite to the negative electrode edge connection line of the second battery cell 10b. One end of the conductive adhesive 20 can cover part of the positive electrode edge connection line of the first battery cell 10a, and the other end of the conductive adhesive 20 can cover part of the negative electrode edge connection line of the second battery cell 10b. This allows the conductive adhesive 20 to connect the positive electrode edge connection line of the first battery cell 10a and the negative electrode edge connection line of the second battery cell 10b, thereby connecting the positive and negative electrodes of the two adjacent stacked battery cells 10 in sequence, adding the voltage and power, and improving the overall performance.

[0092] Similarly, at this time, the negative electrode edge connection line of the first battery cell 10a is positioned opposite to the positive electrode edge connection line of the second battery cell 10b, one end of the conductive adhesive 20 is connected to the negative electrode edge connection line of the first battery cell 10a, and the other end of the conductive adhesive 20 is connected to the positive electrode edge connection line of the second battery cell 10b.

[0093] It should be noted that when the conductive adhesive 20 covers the surface of the battery cell 10 along the stacking direction X of adjacent battery cells 10, the conductive adhesive 20 may also cover part of the fine grid 111. However, in each battery cell 10, one end of each conductive adhesive 20 can only be connected to the fine grid 111 connected to either the positive current output section 11a or the negative current output section 11b. That is, in each battery cell 10, one end of the conductive adhesive 20 can only cover the fine grid 111 of the same polarity, avoiding the conductive adhesive 20 from connecting to fine grids 111 of different polarities.

[0094] Figure 4 This is a schematic diagram of a partial structure where adjacent solar cells 10 are stacked and connected. Along the stacking direction X of the adjacent solar cells 10, the length of the conductive adhesive 20 is L1, 0.5mm≤L1≤8mm.

[0095] For example, along the stacking direction X of adjacent battery cells 10, the length of the conductive adhesive 20 can be 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, etc. The specific length can be set according to actual conditions, and this embodiment does not limit it.

[0096] In this embodiment, the length of the conductive adhesive 20 along the stacking direction X of adjacent battery cells 10 should not be too long or too short. If the length of the conductive adhesive 20 is too long (e.g., L1 > 8 mm), the amount of conductive adhesive 20 used will be large, increasing costs; if the length of the conductive adhesive 20 is too short (e.g., L1 < 0.5 mm), the amount of conductive adhesive 20 used will be small, affecting the connection stability of the two adjacent stacked battery cells 10. Therefore, when the length of the conductive adhesive 20 along the stacking direction X of adjacent battery cells 10 is set between 0.5 mm and 8 mm, the connection stability of the two adjacent stacked batteries is ensured while saving costs.

[0097] Please continue to refer to this. Figure 4 Along the direction Y, which is perpendicular to the stacking direction of the adjacent battery cells 10, the width of the conductive adhesive 20 is L2, 0.2mm≤L2≤5mm.

[0098] For example, the width of the conductive adhesive 20 along the direction Y, which is perpendicular to the stacking direction of the adjacent battery cells 10, can be 0.2mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, etc. The specific width can be set according to the actual situation, and this embodiment does not limit it.

[0099] In this embodiment, the width of the conductive adhesive 20 should not be too long or too short along the direction Y perpendicular to the stacking direction of adjacent battery cells 10. If the length of the conductive adhesive 20 is too long (e.g., L2 > 5 mm), the conductive adhesive 20 may cover two different polarities of fine grids 111, causing the fine grids 111 of different polarities on the same battery cell 10 to be electrically connected. If the length of the conductive adhesive 20 is too short (e.g., L2 < 0.2 mm), there is a risk that some of the conductive adhesive 20 may not cover the positive current output section 11a or the negative current output section 11b, affecting the stability of current transmission.

[0100] In some embodiments, the bottom of the conductive adhesive 20 is stepped along the thickness direction Z of the battery cell 10 to connect two adjacent stacked battery cells 10, thereby ensuring the stability of the connection between the conductive adhesive 20 and the battery cell 10.

[0101] Specifically, Figure 5 This is a side view of two adjacent battery cells 10 stacked together in one embodiment. The conductive adhesive 20 includes a first portion 21 and a second portion 22. In the two adjacent stacked battery cells 10, one battery cell 10 is connected to the first portion 21, and the other battery cell 10 is connected to the second portion 22. The bottom of the first portion 21 and the bottom of the second portion 22 are staggered, so that the bottom of the first portion 21 and the bottom of the second portion 22 are stepped.

[0102] In this embodiment, the top of the first portion 21 and the top of the second portion 22 can be located on the same plane. That is, in this embodiment, the thickness of the first portion 21 and the thickness of the second portion 22 can be different in the thickness direction Z of the battery cell 10.

[0103] Alternatively, please refer to Figure 6 , Figure 6 This is a side view of two adjacent battery cells 10 stacked together in another embodiment. The conductive adhesive 20 includes a first portion 21 and a second portion 22. In the two adjacent stacked battery cells 10, one battery cell 10 is connected to the first portion 21, and the other battery cell 10 is connected to the second portion 22. The first portion 21 and the second portion 22 are staggered, so that the first portion 21 and the second portion 22 are stepped.

[0104] In this embodiment, the top of the first portion 21 and the top of the second portion 22 can also be staggered. That is, in this embodiment, the thickness of the first portion 21 and the thickness of the second portion 22 can be the same in the thickness direction Z of the battery cell 10.

[0105] Alternatively, the conductive adhesive 20 can be in other shapes, as long as it can achieve electrical connection between two adjacent stacked battery cells 10. The specific shape of the conductive adhesive 20 can be set according to the actual situation, and this embodiment does not limit it.

[0106] In some embodiments, the conductive adhesive 20 can be prepared by printing using a printing screen 30. The structure of the printing screen 30 is described in [reference needed]. Figure 7 and 8 , Figure 7 This is a top view of the printing screen 30. The printing screen 30 is provided with a plurality of evenly arranged printing screen holes 31, which penetrate the printing screen 30 along the thickness direction Z. Figure 8 The following is a side view of a portion of the structure of the printing screen 30. The bottom of the printing screen 30 is also provided with a plurality of first abutting surfaces 32 and second abutting surfaces 33 arranged in sequence. The first abutting surfaces 32 and second abutting surfaces 33 are staggered, and the connection between the first abutting surfaces 32 and the second abutting surfaces 33 forms a stepped surface, so that the bottom of the printing screen 30 is stepped.

[0107] When the printing screen 30 is used to print conductive adhesive 20 on the battery cell 10, the first contact surface 32 abuts against one of the two adjacent stacked battery cells 10, and the second contact surface 33 abuts against the other of the two adjacent stacked battery cells 10. This allows the printing screen 30 to make contact with both adjacent stacked battery cells 10. In this way, the force applied by the printing screen 30 to the two adjacent stacked battery cells 10 during the printing process is the same, thereby reducing the risk of the battery cell 10 breaking due to excessive stress at the edge.

[0108] Figure 9 and Figure 10 This is a side view of the printing screen 30 during the printing of conductive adhesive 20 onto the battery cell 10. The printing screen 31 is provided with a first adhesive groove 311, a second adhesive groove 312, and a printing channel 313 that are connected to each other. The first adhesive groove 311 and the second adhesive groove 312 are stepped, and the printing channel 313 is located above the first adhesive groove 311 and the second adhesive groove 312.

[0109] When the conductive adhesive 20 is printed on the battery cell 10 using the printing screen 30, in two adjacent stacked battery cells 10, the first adhesive groove 311 is correspondingly disposed above one of the battery cells 10, and the groove opening of the first adhesive groove 311 is correspondingly disposed above the battery cell 10. The groove opening of the second adhesive groove 312 is correspondingly disposed above the other battery cell 10, and the groove opening of the second adhesive groove 312 is correspondingly disposed above the battery cell 10. The conductive adhesive 20 can flow along the printing channel 313 to the first adhesive groove 311 and the first adhesive groove 311, thereby being printed on the two adjacent stacked battery cells 10, realizing the connection of the two adjacent stacked battery cells 10.

[0110] Along the thickness direction Z of the printing screen 30, the projection surface of the printing channel 313 can cover at least part of the projection surface of the first glue tank 311 and at least part of the projection surface of the second glue tank 312, so that the printing channel 313 is connected to both the first glue tank 311 and the second glue tank 312, so that the conductive adhesive 20 flows along the printing channel 313 to the first glue tank 311 and the second glue tank 312.

[0111] Please continue to refer to this. Figure 9 Along the thickness direction Z of the printing screen 30, the projection surface of the printing channel 313 can completely cover the projection surfaces of the first glue tank 311 and the second glue tank 312. In other words, neither the first glue tank 311 nor the second glue tank 312 has a top wall on the side closest to the printing channel 313, and the printing channel 313 is completely connected to the first glue tank 311 and the second glue tank 312. This allows the conductive adhesive 20 to flow rapidly along the printing channel 313 into the first glue tank 311 and the second glue tank 312, improving production efficiency.

[0112] In this embodiment, the amount of conductive adhesive 20 in the first adhesive tank 311 and the second adhesive tank 312 can be the same, so that the conductive adhesive 20 has a stepped structure. Alternatively, the amount of conductive adhesive 20 in the first adhesive tank 311 and the second adhesive tank 312 can be different, so that the bottom of the conductive adhesive 20 is stepped and the top of the conductive adhesive 20 is flat. The specific method can be set according to the actual situation, and this embodiment does not limit it.

[0113] Please continue to refer to this. Figure 10 Along the thickness direction Z of the printing screen 30, the projection surface of the printing channel 313 covers part of the projection surface of the first adhesive groove 311 and part of the projection surface of the second adhesive groove 312. That is, both the first adhesive groove 311 and the second adhesive groove 312 have a top wall on the side near the printing channel 313. The printing channel 313 is connected to part of the first adhesive groove 311 and part of the second adhesive groove 312. The top walls of the first adhesive groove 311 and the second adhesive groove 312 limit the thickness of the conductive adhesive 20 printed on the two adjacent stacked battery cells 10, thereby ensuring that the thickness of the conductive adhesive 20 finally printed on the two adjacent stacked battery cells 10 is consistent.

[0114] Figure 11 This is a side view of the printing screen 30, the battery cell 10, and the assembly platform 40. When the conductive adhesive 20 is printed on the battery cell 10, the battery cell 10 can be placed on the assembly platform 40. The placement surface of the assembly platform 40 can be set as a stepped surface to better support the stacked battery cells 10, thereby further improving the stability of the shingled battery cells during the printing process.

[0115] This embodiment also provides a back-contact solar tandem module, which includes a top cell, an intermediate connecting layer, and a bottom cell, with the intermediate connecting layer connecting the bottom cell and the top cell. The top cell is one of a perovskite cell, a cadmium telluride solar cell, a copper indium gallium selenide solar cell, or a gallium arsenide solar cell, and the bottom cell is the aforementioned back-contact photovoltaic module or solar cell.

[0116] The intermediate interconnect layer is typically selected from transparent materials with high refractive index. An effective intermediate interconnect layer needs high light transmittance to reduce light reflection and absorption at the interconnect layer interface, and good conductivity to reduce the impact of series resistance on device performance. For example, transparent conductive metal oxide thin films (ITO) can be used as intermediate interconnect layers.

[0117] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A printing screen, characterized in that, The printing screen (30) has a plurality of uniformly arranged printing mesh holes (31), and the bottom of the printing mesh holes (31) is stepped. The printing screen (30) is provided with a first contact surface (32) and a second contact surface (33). The first contact surface (32) is used to connect with one of the adjacent stacked back contact solar cells (10), and the second contact surface (33) is used to connect with the other of the adjacent stacked back contact solar cells (10). The first abutting surface (32) and the second abutting surface (33) are connected to form a stepped surface; The printing mesh (31) is provided with a first glue groove (311), a second glue groove (312) and a printing channel (313) that are connected to each other. The first glue tank (311) and the second glue tank (312) are stepped, and the printing channel (313) is located above the first glue tank (311) and the second glue tank (312).

2. The printing screen according to claim 1, characterized in that, Along the thickness direction (Z) of the printing screen (30), the projection surface of the printing channel (313) can cover at least a portion of the projection surface of the first glue tank (311) and at least a portion of the projection surface of the second glue tank (312).

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