Battery piece, battery string, preparation method of battery string and photovoltaic module

Abstract

The invention provides a battery piece, a battery string, a preparation method of the battery string and a photovoltaic module. A first grid line layer of the battery piece comprises a plurality of first interconnection main grids which are arranged at intervals, a second main grid layer is arranged on the back face of the battery piece, the second main grid layer is provided with a plurality of second interconnection main grids and a plurality of current collection enhancing main grids, and the first interconnection main grids and the second interconnection main grids are arranged in a one-to-one correspondence mode in the thickness direction of the battery piece. The two sides of each first interconnection main grid are respectively provided with at least one current collection enhancement main grid. According to the battery piece provided by the invention, the current collection capability of the battery piece is improved, the current transmission loss is reduced, the filling factor of a photovoltaic module is improved, meanwhile, the optical loss caused by optical shielding on the front surface of the battery piece is reduced, the short-circuit current is improved, and the short-circuit current and the filling factor are optimized at the same time.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a method for preparing solar cells, solar cell strings, solar cell strings, and photovoltaic modules. Background Technology

[0002] Improving the efficiency of photovoltaic modules is a crucial issue for the photovoltaic cell industry. In traditional cell layout design, when the positive and negative busbars are located on opposite sides of the cell, the positive and negative busbars on the two sides of the cell are arranged opposite each other along the thickness direction of the cell.

[0003] In general, the main technical means to reduce current transmission losses and improve the fill factor of photovoltaic modules is to increase the number of busbars. However, a larger number of busbars means more optical shading of the cells, especially the front side of the cells, which negatively impacts the short-circuit current of the photovoltaic module. Therefore, there are limits to the increase in the number of busbars.

[0004] Therefore, optimizing the balance between short-circuit current and fill factor is a problem that needs to be considered to improve the efficiency of photovoltaic modules. Summary of the Invention

[0005] The first aspect of this application provides a solar cell having a front side and a back side. A first main grid layer is disposed on the front side, the first grid layer including a plurality of spaced-apart first interconnect main grids. A second main grid layer is disposed on the back side, the second main grid layer having a plurality of second interconnect main grids and a plurality of current collection enhancement main grids.

[0006] Multiple first interconnect main grids and multiple second interconnect main grids are arranged in a one-to-one correspondence in the thickness direction of the solar cell, and at least one current collection enhancement grid is arranged on both sides of each first interconnect main grid.

[0007] A second aspect of this application provides a battery string, which is formed by connecting the battery cells of the first aspect of this application in series. Current collection enhancement strips are correspondingly provided on the current collection enhancement main grid, and different interconnecting strips are respectively provided on the first interconnecting main grid and the second interconnecting main grid of the same battery cell.

[0008] In the same cell, the current harvesting enhancement solder strip transmits current to the interconnect solder strip through a lateral conductive structure.

[0009] In two adjacently arranged solar cells, the first interconnecting main grid of one solar cell and the second interconnecting main grid of the other solar cell are electrically connected by interconnecting strips.

[0010] The third aspect of this application provides a battery string, which is formed by connecting battery cells as described in the first aspect of this application. Current collection enhancement strips are welded on the current collection enhancement grid, and different interconnection strips are welded to the first interconnect grid and the second interconnect grid of the same battery cell respectively. Multiple current collection enhancement strips and multiple interconnection strips form a strip layer on the back of the battery cell.

[0011] A connecting solder strip is provided on the side of the solder strip layer facing away from the second main gate layer. The connecting solder strip extends laterally and is electrically connected to each current collection enhancement solder strip and each interconnecting solder strip in the solder strip layer.

[0012] The fourth aspect of this application provides a method for preparing a battery string, comprising:

[0013] On the stringing equipment, first lay the current harvesting enhancement ribbon and the interconnect ribbon, then lay the solar cells face down on the current harvesting enhancement ribbon and the interconnect ribbon; or,

[0014] A current-collecting enhancement solder strip is laid and fixed on the back of the solar cell. Interconnect solder strips are then laid on a stringing machine. The solar cell with the current-collecting enhancement solder strip already laid on it is placed face down on the interconnect solder strips; or...

[0015] Interconnecting ribbons and cells are alternately laid on a stringing equipment to form a pre-connected cell string. Current collection enhancement ribbons are laid and fixed on the back of each cell in the pre-connected cell string.

[0016] The fifth aspect of this application provides a method for preparing a battery string, comprising:

[0017] First, lay the connecting strips on the stringing equipment. Then, lay the current collection enhancement strips and interconnecting strips on the connecting strips. Finally, lay the solar cells face down on the current collection enhancement strips and interconnecting strips; or...

[0018] Interconnecting ribbons and cells are alternately laid on a stringing equipment to form a pre-connected cell string. Current collection enhancement ribbons are laid and fixed on the back of each cell in the pre-connected cell string. Connecting ribbons are laid on the current collection enhancement ribbons and interconnecting ribbons.

[0019] The sixth aspect of this application provides a photovoltaic module, including the battery strings of the third and fourth aspects of this application.

[0020] Beneficial effects:

[0021] The solar cell provided in the first aspect of this application, in addition to having main grids on the back side corresponding to the number of main grids on the front side for interconnection, also improves the current collection capability of the solar cell by setting multiple current collection enhancement grids, reduces current transmission loss, and improves the fill factor of the photovoltaic module. Simultaneously, it does not design current collection enhancement grids on the front side of the solar cell, thus avoiding optical losses caused by optical shading on the front side of the solar cell, increasing short-circuit current, and thereby improving the conversion efficiency of the solar cell. The solar cell provided in the first aspect of this application simultaneously optimizes short-circuit current and fill factor.

[0022] The battery string provided in the second aspect of this application integrates the current collection enhancement function and the interconnection function in the battery string by correspondingly setting current collection enhancement solder strips, interconnection solder strips used in conventional series battery cells, and lateral conductive structures on the current collection enhancement grid, thereby enhancing the current collection performance of the battery string.

[0023] The battery string provided in the third aspect of this application integrates the current collection enhancement function and the interconnection function in the electric field string by correspondingly setting current collection enhancement solder strip, interconnection solder strip used in conventional series battery cells, and connecting solder strip on the current collection enhancement grid, thereby enhancing the current collection performance of the battery string.

[0024] The battery string preparation methods provided in the fourth and fifth aspects of this application are applicable to the preparation of the battery strings provided in this application, simplifying the preparation steps and improving the battery string preparation efficiency.

[0025] The photovoltaic module provided in the sixth aspect of this application reduces optical losses on the front side of the photovoltaic module. Furthermore, by setting a current-collecting enhancement grid and corresponding current-collecting enhancement solder strips on the back of the cells to enhance current collection, the current loss of the photovoltaic module is reduced, the fill factor of the photovoltaic module is increased, and the power gain of the photovoltaic module is achieved, resulting in a high-power photovoltaic module. At the cell string and photovoltaic module ends, current-collecting enhancement solder strips are correspondingly set on the current-collecting enhancement grid. The cross-section of the solder strips is wider than that of the grid, reducing the transmission resistance between cells and thus reducing transmission losses. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of a typical solar cell main grid structure;

[0028] Figure 2 yes Figure 1Schematic diagram of cross-sectional structure along the MM direction;

[0029] Figure 3 It is by Figure 1 A schematic diagram of the back structure of a battery string made from the shown battery cells;

[0030] Figure 4 yes Figure 3 The diagram shows a cross-sectional structure of the battery string along the NN direction.

[0031] Figure 5 yes Figure 3 The diagram shows a cross-sectional view of the battery string along the EE direction.

[0032] Figure 6 This is a schematic diagram of the back grid line structure of the battery cell in one embodiment of the first aspect of this application;

[0033] Figure 7 yes Figure 6 A schematic diagram of the cross-sectional structure along the FF direction;

[0034] Figure 8 This is a schematic diagram of a battery cell grid line structure containing lateral transmission grid lines in another embodiment of the first aspect of this application;

[0035] Figure 9 This is a schematic diagram of the back grid line structure of a battery cell containing a conductive layer in another embodiment of the first aspect of this application;

[0036] Figure 10 This is a simplified side view of a battery cell with a single-layer conductive layer in another embodiment of the first aspect of this application;

[0037] Figure 11 This is a simplified side view of a battery cell with a double-layer structure in another embodiment of the first aspect of this application;

[0038] Figure 12 This is a simplified side view of another battery cell structure with a double-layer structure in the conductive layer of another embodiment of the first aspect of this application;

[0039] Figure 13 This is a simplified side view of a battery cell with a three-layer conductive layer in a further embodiment of the first aspect of this application;

[0040] Figure 14 This is a simplified side view of another battery cell structure with a three-layer conductive layer in a further embodiment of the first aspect of this application;

[0041] Figure 15 This is a top view of the rear structure of the battery string in one embodiment of the second aspect of this application;

[0042] Figure 16 Is it like this? Figure 15 A schematic diagram of a cross-sectional structure of the battery string shown;

[0043] Figure 17 This is a top view of the rear structure of the battery string in another embodiment of the second aspect of this application;

[0044] Figure 18 Is it like this? Figure 17 A schematic diagram of a cross-sectional structure of the battery string shown;

[0045] Figure 19 Is it like this? Figure 17 Another cross-sectional view of the battery string shown;

[0046] Figure 20 Is it like this? Figure 17 Another cross-sectional structural diagram of the battery string shown;

[0047] Figure 21 This is a side view of the battery string structure in another embodiment of the second aspect of this application;

[0048] Figure 22 This is a top view of the rear structure of the battery string in one embodiment of the third aspect of this application;

[0049] Figure 23 Is it like this? Figure 22 A schematic diagram of a cross-sectional structure of the battery string shown;

[0050] Figure 24 This is a schematic flowchart of a method for preparing a battery string according to an embodiment of the fourth aspect of this application;

[0051] Figure 25 This is a schematic diagram of the process for preparing a battery string in another embodiment of the fourth aspect of this application;

[0052] Figure 26 This is a schematic diagram of the process for preparing a battery string in another embodiment of the fifth aspect of this application;

[0053] Figure 27 This is a schematic diagram of the process for preparing a battery string in another embodiment of the fifth aspect of this application.

[0054] Figure label:

[0055] Battery cell-1;

[0056] First interconnect main gate - 11; Second interconnect main gate - 12; Current harvesting enhancement main gate - 13; Pad - 14; Main gate line - 15; Harpoon line - 151; Lateral transmission gate line - 16; Lateral transmission segment - 161; Conductive layer - 17; Conductive adhesive layer - 171; Adhesive block - 1711; Conductive interconnect layer - 172; Buffer layer - 173; Buffer protection block - 1731; Conductive layer electrical transmission portion - 17a; Battery string - 2; Current harvesting enhancement solder ribbon - 21; Interconnect solder ribbon - 22; Connecting solder ribbon - 23; Adhesive dot - 3; First side - L. Detailed Implementation

[0057] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0058] In the description of this application, it should be noted that the terms "first", "second", and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0059] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0060] like Figure 1 As shown, a typical solar cell 1 in battery technologies including, but not limited to, TOP (ConTunnel Oxide Passivated Contact), PERC (Passivated Emitter and Rear Cell), and HJT (Heterojunction Technology) has a number and position of main grids on its front and back sides, respectively. In a typical solar cell 1, the main grid includes main grid lines 15, a plurality of pads 14 evenly spaced on the main grid lines 15, and harpoon lines 151 connected to the edge of the solar cell 1. In some examples, the main grid lines 15 of the solar cell 1 generally do not extend directly to the edge of the solar cell 1; the main grid lines 15 have pads 14 at both ends in their extension direction, and the starting ends of the harpoon lines 151 are connected to the pads 14 at both ends of the main grid lines 15, with the openings of the harpoon lines 151 facing the edge of the solar cell 1.

[0061] A first interconnecting main grid 1 is disposed on the front side of the solar cell 1, and a second interconnecting main grid 2, corresponding to the position of the first interconnecting main grid 1, is disposed on the back side. Typically, the main grid lines 15 of the solar cell 1 extend along the grid direction, passing through multiple pads 14 disposed on the surface of the solar cell 1. The pads 14 are electrically connected to the main grid lines 15, and the main grid lines 15 of the solar cell 1 are connected to external solder strips through the pads 14 to form a cell string 2. The pads 14 are used to ensure reliable contact between the main grid lines 15 and the solder strips. The harpoon wire 151 prevents breakage and microcracks at the edge of the solar cell 1 due to protrusions of the solder strips corresponding to the main grid during the post-welding flow process and lamination, and also prevents grid breakage caused by solder strip movement between two interconnected solar cells 1, ensuring current collection at the cell edge. The distance from the starting end of the harpoon wire 151 to the nearest edge of the solar cell 1 is 4mm to 9mm. Figure 2 As shown, the main grids on the front and back of the typical battery cell 1 are arranged in a one-to-one correspondence. That is, the first interconnecting main grid 1 and the second interconnecting main grid 2 are respectively arranged in a one-to-one correspondence on the front and back sides, meaning that the positions and numbers of the first interconnecting main grid 1 and the second interconnecting main grid 2 are consistent. Figures 3 to 5 As shown, in a typical cell string 2, one part of the interconnecting solder ribbon 22 is soldered to the front side of one of the two adjacent cells 1, and the other part of the interconnecting solder ribbon 22 passes through the space between the opposite sides of the two adjacent cells 1 and wraps around to the back side of the other adjacent cell 1. The remaining part of the interconnecting solder ribbon 22 is then soldered to the back side of one of the two adjacent cells 1. This typical cell 1 and cell string 2 can improve current collection capacity, reduce current transmission loss, and increase the fill factor of the photovoltaic module by increasing the number of main grids and solder ribbons, thereby improving efficiency. However, this method also causes more severe optical shading, resulting in a loss of short-circuit current in the photovoltaic module.

[0062] To address the aforementioned problems, embodiments of this application provide a method for fabricating a solar cell, a solar cell string, a solar cell string, and a photovoltaic module. For example... Figures 6 to 7 As shown, the first aspect of this application provides a battery cell 1, which has a front side and a back side. A first main grid layer is disposed on the front side, and the first main grid layer includes a plurality of first interconnect main grids 1 spaced apart. A second main grid layer is disposed on the back side, and the second main grid layer is disposed with a plurality of second interconnect main grids 2 and a plurality of current collection enhancement main grids 13.

[0063] Multiple first interconnecting main grids 1 and multiple second interconnecting main grids 2 are arranged in a one-to-one correspondence in the thickness direction of the cell 1, and at least one current collection enhancement grid 13 is arranged on both sides of each first interconnecting main grid 1.

[0064] The solar cell 1 provided in the first aspect of this application, in addition to the main grids on the back side corresponding to the number of main grids on the front side and used for interconnection, also improves the current collection capability of the solar cell 1 by setting multiple current collection enhancement grids 13, reduces current transmission loss, and improves the fill factor of the photovoltaic module. At the same time, the current collection enhancement grids 13 are not designed on the front side of the solar cell 1, which avoids optical loss caused by optical shading on the front side of the solar cell 1, increases short-circuit current, and thus improves the electric field conversion efficiency.

[0065] Furthermore, compared to the battery cell 1 in the prior art, multiple current collection enhancement grids 13 can be added to the back of the battery cell 1 to improve its current collection capability without adding optical obstruction to the front side, thus ensuring its short-circuit current.

[0066] The solar cell 1 provided in the first aspect of this application simultaneously optimizes and improves the short-circuit current and fill factor.

[0067] In some optional embodiments of the first aspect of this application, the same number of current-collecting enhancement main gates 13 are respectively provided on both sides of each first interconnect main gate 1. In some examples, one to three current-collecting enhancement main gates 13 are respectively provided on both sides of each first interconnect main gate 1.

[0068] In some optional embodiments of the first aspect of this application, the second interconnecting main grid 2 divides the solar cell 1 into multiple current enhancement regions, and multiple current collection enhancement main grids 13 are evenly spaced in each current enhancement region. In these embodiments, the current collection efficiency can be further enhanced and the current gain of each current enhancement region of the solar cell 1 can be balanced.

[0069] In some optional embodiments of the first aspect of this application, the width of the current harvesting enhancement main gate 13 is 10μm to 25μm, and the height is 5μm to 15μm. A pad 14 is provided on the current harvesting main gate, with a width of 0.4μm to 1μm, a length of 0.4mm to 1.5mm, and a height of 5μm to 15μm. For example, the width of the current harvesting enhancement main gate 13 can be 10μm, 15μm, 20μm, or 25μm, and the height can be 5μm, 10μm, or 15μm, etc. The width of the pad 14 on the current harvesting main gate can be 0.1μm, 0.6μm, 0.8μm, or 1μm, the length can be 0.4μm, 0.6μm, 0.8μm, 1μm, 1.2μm, or 1.5μm, etc., and the height can be 5μm, 10μm, or 15μm, etc.

[0070] In some optional embodiments of the first aspect of this application, the two ends of the second interconnecting main grid 2 are provided with harpoon lines 151 with openings facing the edge of the battery cell 1, and at least one end of the current collection enhancement main grid 13 extends in a straight line along its own length direction to the edge of the battery cell 1.

[0071] In some optional embodiments of the first aspect of this application, the two ends of the first interconnect main grid 1 are provided with fork lines 151 with openings facing the edge of the cell 1. Both ends of the first interconnect main grid 1 and both ends of the second interconnect main grid 2 are provided with fork lines 151, which can facilitate the connection with interconnecting solder ribbons 22 during the subsequent fabrication of the cell string 2, and avoid cell breakage and microcracks caused by the main grid and the corresponding solder ribbon forming a protrusion at the edge of the cell 1, thereby improving the fabrication quality of the cell string 2, avoiding grid breakage and ensuring the electrical performance and photoelectric conversion efficiency of the cell 1.

[0072] like Figure 6 As shown, at least one end of the current collection enhancement grid 13 does not have a fork wire 151. Since the grid enhances current collection capability and does not participate in the welding of the battery string 2 to the interconnecting solder strip 22 during manufacturing, the absence of a fork wire 151 at the edge of the battery cell 1 saves on grid paste usage and reduces manufacturing costs. In some examples, the grid paste for the battery collection enhancement grid includes, but is not limited to, silver paste, silver-coated copper paste, and copper paste. Besides using conventional printing and sintering processes, the battery collection enhancement grid can also be constructed using copper electroplating processes to achieve cost reduction.

[0073] like Figure 7 and Figure 8 As shown, the first interconnecting main grid 1 and the second interconnecting main grid 2 are arranged in a one-to-one correspondence in number and position on the front and back sides of the battery cell 1. The current collection enhancement main grid 13 is located only on the back side of the battery cell 1 and is located on at least one side of the second interconnecting main grid 2.

[0074] The solar cell 1 includes a lateral conductive structure disposed on the back side, and a plurality of second interconnect main grids 2 and a plurality of current collection enhancement main grids 13 are electrically connected in the lateral direction through the lateral conductive structure, which is perpendicular to the extension direction of the second interconnect main grids.

[0075] The transverse direction is coplanar with the extension direction of the main grid of the second main grid layer and perpendicular to the thickness direction of the cell 1.

[0076] The lateral conductive structure enables the second interconnecting main grid 2 and the current collection enhancement main grid 13 on the back of the battery cell 1 to be electrically connected. In the subsequent process of forming the battery string 2, all the solder strips on the back can also be electrically connected, reducing the loss caused by lateral current transmission only by the fine grid, improving energy conversion efficiency and battery performance.

[0077] In some optional embodiments of this application, in the extension direction of the second interconnecting main grid, the lateral conductive structure is disposed close to the first side L, the first side L being one of the two opposite sides of the battery cell 1, and the distance between the lateral conductive structure and the first side L is 0.1mm to 2mm.

[0078] In some optional embodiments of this application, the battery cell 1 is a half-cell battery cell 1, and the first side L is formed with a cut surface.

[0079] In some specific examples, the typical stringing arrangement is with the cut surfaces facing forward. That is, the cut surfaces of multiple battery cells 1 in the battery string 2 are aligned with the current transmission direction in the battery string 2. The transverse conductive structure is positioned close to the cut surfaces to further shorten the current transmission distance, reduce voltage drop and energy loss, and significantly improve the output efficiency of the battery string 2.

[0080] In some optional embodiments, both the second interconnect main gate 2 and the current collection enhancement main gate 13 are provided with a plurality of pads 14 spaced apart along the extension direction of the main gate. In the lateral direction, the plurality of pads 14 are spaced apart and aligned to form a pad row. The lateral conductive structure covers the pad row closest to the first side L in the thickness direction of the cell 1.

[0081] In some optional embodiments, the spacing between the pad row closest to the first side L and the first side L is 0.1mm to 2mm, such as 0.1mm, 0.5mm, 1mm, 1.5mm, or 2mm. In some specific examples, the pad row is moved outwards from the first side L, and in the thickness direction of the cell 1, the lateral conductive structure contacts and covers the pad row closest to the first side L. Since the contact surface between the pad 14 and the lateral conductive structure is larger than the contact surface between the main bus line 15 and the lateral conductive structure, the contact arrangement between the lateral conductive structure and the pad row can have a better contact effect, improving the quality of lateral current transmission. The electrical connection between the lateral conductive structure and the pad row closest to the first side L can also improve the current collection capability at the edge of the cell 1.

[0082] like Figure 8 As shown, in some optional embodiments of the first aspect of this application, the lateral conductive structure includes a lateral transmission gate line 16 disposed on the back side and disposed in the same layer as the second gate line layer, and a plurality of second interconnecting main gates 2 and a plurality of current collection enhancement main gates 13 are electrically connected in the lateral direction through the lateral transmission gate line 16.

[0083] In these embodiments, the lateral transmission gate lines 16 can be fabricated simultaneously during the steps of fabricating the second interconnecting main gate 2 and the multiple current collection enhancement main gates 13 using processes such as screen printing.

[0084] In some optional embodiments of this application, the lateral transmission gate line 16 includes a plurality of lateral transmission segments 161, each lateral transmission segment 161 having its two ends connected to two adjacent current collection enhancement main gates 13, or connected to an adjacent current collection enhancement main gate 13 and a second interconnecting main gate 2.

[0085] In some optional embodiments of this application, the thickness of the lateral transmission gate line 16 is 5μm to 50μm, such as 5μm, 10μm, 20μm, 30μm, 40μm, or 50μm, and the width is 20μm to 2000μm, such as 20μm, 100μm, 500μm, 1000μm, 1500μm, or 2000μm. In these embodiments, the lateral transmission gate line 16 can be prepared using silver paste.

[0086] It should be noted that, in the embodiments of this application, "thickness" refers to the dimension along the direction from the front to the back of the battery cell or from the back to the front. "Width" refers to the dimension along the shorter side in the direction parallel to the front or back of the battery cell.

[0087] In some optional embodiments of this application, the lateral transmission gate line 16 is fabricated using copper wire, and the width of the lateral transmission gate line 16 is 500 μm to 2000 μm. In these embodiments, the lateral transmission gate line 16 can be constructed using an electroplating copper process to form a conductive copper layer, thereby reducing the fabrication cost of the gate line. The larger the width of the lateral transmission gate line 16 within this range, the lower the current transmission loss.

[0088] In some optional embodiments of this application, the length of the lateral transmission gate line 16 is equal to the spacing between the two most distant current-collecting enhancement main gates 13 in the lateral direction. In these embodiments, the length of the lateral transmission gate line 16 is set to the shortest length that allows all the second interconnecting main gates 2 and the current-collecting enhancement main gates 13 to be electrically connected in the lateral direction via the lateral transmission gate line 16, which can save the amount of gate line metal paste used and reduce manufacturing costs.

[0089] like Figure 9 As shown, in some other embodiments of the first aspect of this application, the lateral conductive structure includes a conductive layer 17, which is disposed on the side of the second main gate layer opposite to the first main gate layer and is electrically connected to the second interconnect main gate 2 and the current collection enhancement main gate 13.

[0090] In some embodiments of the first aspect of this application, in the lateral direction, the length of the conductive layer 17 is greater than the spacing between the two furthest current collection enhancement main grids 13 and less than the spacing between the two opposite sides of the battery cell 1. In these embodiments, the conductive layer 17 comprises conductive adhesive, and the lateral length of the conductive layer 17 is equal to that of the side of the battery cell 1. This helps to alleviate edge damage and microcracks caused by mechanical stress at various points on the edge of the battery cell 1 during the subsequent formation of the battery string 2. The full-coverage design of the conductive layer 17 in the lateral direction during the welding process avoids the impact of thermal expansion differences on the structure of the battery cell 1.

[0091] In some embodiments of the first aspect of this application, the conductive layer 17 is laid across the entire back surface of the solar cell 1, which is particularly suitable for single-glass photovoltaic modules. Laying the conductive layer 17 across the entire back surface can further enhance the current transmission function of the lateral conductive structure and improve current collection capability.

[0092] In some alternative embodiments, such as Figure 9 small picture a As shown, multiple pads 14 are spaced apart along the extension direction of the main grid on both the second interconnect main grid 2 and the current collection enhancement main grid 13. In the lateral direction, the multiple pads 14 are spaced apart and aligned to form a pad row. The lateral conductive structure covers the first pad row closest to the first side L in the thickness direction of the cell 1. The distance between the first pad row and the first side L is 0.1mm to 2mm.

[0093] In some embodiments of the first aspect of this application, the conductive layer 17 is elongated, and in the direction of extension of the second interconnect main grid, the width of the conductive layer 17 is less than half the width of the solar cell 1, and one long side of the conductive layer 17 is aligned with the first side L. In these embodiments, the conductive layer 17 is elongated, which can reduce the manufacturing cost of the solar cell 1 and avoid the degree of shading of the back light by the conductive layer 17 on the back of the solar cell 1 during the manufacturing process of the double-glass photovoltaic module, thereby ensuring the bifaciality factor (the ratio of the power generation capacity on the back of the photovoltaic module to the power on the front, i.e., the maximum power bifaciality factor) of the double-glass photovoltaic module.

[0094] like Figure 10 As shown, in some optional embodiments of the first aspect of this application, the conductive layer 17 is a single-layer structure, and the conductive layer 17 is made of conductive adhesive. The conductive adhesive in photovoltaic modules is a special adhesive that combines conductive and adhesive functions. Conductive adhesive generally consists of two parts: a matrix and a conductive filler. Commonly used matrices include epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane, and acrylic resin, etc. Conductive fillers typically include carbon, metal, and metal oxides. The conductive filler can be metal powders such as gold, silver, and copper.

[0095] In some examples, the width of the conductive layer 17 is 0.5 mm to 2 mm, and the thickness of the conductive layer 17 is 5 μm to 200 μm.

[0096] like Figures 11 to 12 As shown, in some optional embodiments of the first aspect of this application, the conductive layer 17 includes a conductive adhesive layer 171 and a conductive interconnect layer 172 stacked on the second main gate layer. The conductive interconnect layer 172 is continuously laid on the conductive adhesive layer 171 in the transverse direction. The conductive interconnect layer 172 is bonded to and electrically connected to the second main gate layer through the conductive adhesive layer 171.

[0097] In some optional embodiments of the first aspect of this application, the conductive adhesive layer 171 is made of conductive adhesive, and the width of the conductive adhesive layer 171 is 0.5mm to 2mm, for example, 0.5mm, 1mm, 1.5mm or 2mm, etc. The thickness of the conductive adhesive layer 171 is 5μm to 200μm, for example, 5μm, 10μm, 50μm, 100μm, 150μm or 200μm, etc. The conductive interconnect layer 172 is made of conductive metal material (e.g., copper strip), and the width of the conductive interconnect layer 172 is 0.5mm to 2mm, for example, 0.5mm, 1mm, 1.5mm or 2mm, etc. The thickness of the conductive interconnect layer 172 is 10μm to 100μm, for example, 10μm, 30μm, 50μm, 70μm, 90μm or 100μm, etc.

[0098] like Figure 11 As shown, in some examples of these embodiments, the conductive adhesive layer 171 includes a plurality of spaced adhesive blocks 1711, with each second interconnect main gate 2 and each current harvesting enhancement main gate 13 correspondingly provided with an adhesive block 1711. The aforementioned conductive interconnect layer 172 is provided on the side of all adhesive blocks 1711 facing away from the second main gate layer. The current of the second interconnect main gate 2 and the current harvesting enhancement main gate 13 is transmitted to the conductive interconnect layer 172 through the conductive effect of the adhesive blocks. The conductive interconnect layer 172 is used to laterally collect the current of all the second interconnect main gates 2 and all the current harvesting enhancement main gates 13.

[0099] like Figure 12 As shown, in some examples of these embodiments, the conductive adhesive layer 171 is continuously laid on the second main gate layer in the lateral direction, and the conductive adhesive layer 171 is bonded to each second interconnect main gate 2 and each current collection enhancement main gate 13. In these embodiments, the conductive adhesive layer 171 extends laterally through the corresponding positions of each second interconnect main gate 2 and each current collection enhancement main gate 13, which can reduce current transmission loss.

[0100] In some optional embodiments of the first aspect of this application, the conductive layer 17 further includes a buffer layer 173 disposed on the side of the conductive interconnect layer 172 opposite to the conductive adhesive layer 171. The buffer layer 173 includes a plurality of buffer protection blocks 1731 disposed at intervals, and the interval between two adjacent buffer protection blocks 1731 corresponds to at least one second interconnect main gate 2.

[0101] In these embodiments, the lateral conductive structure is provided with a three-layer structure, including a conductive adhesive layer 171, a conductive interconnect layer 172, and a buffer layer 173 stacked on the second main gate layer.

[0102] like Figure 13As shown, in some optional embodiments of this application, the spacing between two adjacent buffer protection blocks 1731 in the buffer layer 173 corresponds to a second interconnecting main gate 2, and the buffer protection blocks 1731 cover the current collection enhancement main gate 13.

[0103] like Figure 14 As shown, in some optional embodiments of this application, the conductive layer 17 further includes a buffer layer 173 disposed on the side of the conductive interconnect layer 172 facing away from the conductive adhesive layer 171. The buffer layer 173 includes a plurality of buffer protection blocks 1731 disposed at intervals. The interval between two adjacent buffer protection blocks 1731 corresponds one-to-one with each main gate in the second main gate layer. Each main gate in the second main gate layer includes a second interconnect main gate 2 and a current collection enhancement main gate 13.

[0104] In some examples of these embodiments, the buffer layer 173 and the conductive interconnect layer 172 are bonded together using a layer of conductive adhesive or other non-conductive adhesive material.

[0105] In these embodiments, the buffer layer 173 is provided so that when the battery string 2 is subsequently manufactured, the height of the buffer layer 173 is set to be consistent with that of the interconnect solder ribbon 22. This avoids the interconnect solder ribbon 22 being placed on the battery cell 1, which would cause excessive stress concentration in the battery cell 1 due to the significant height difference between the interconnect solder ribbon 22 and the surface of the battery cell 1, thereby causing microcracks. This ensures the power generation efficiency of the battery cell 1, protects the electrical performance of the battery cell 1, and extends the life of the photovoltaic module.

[0106] In some examples of these embodiments, the spacing between two adjacent buffer protection blocks 1731 is 1mm to 3mm, such as 1mm, 2mm, or 3mm. The thickness of the buffer layer 173 is 0.05mm to 0.3mm, such as 0.05mm, 0.1mm, 0.2mm, or 0.3mm. The buffer protection block 1731 is made of polyolefin polymer material or conductive metal material. The polyolefin polymer material is a flexible material, including but not limited to EVA (Ethylene Vinyl Acetate Copolymer), PO (Polyolefins), etc., and the conductive metal material includes copper and aluminum, that is, the buffer layer 173 is a copper layer or an aluminum layer. The buffer layer 173 and the conductive interconnect layer 172 are stacked together, and the current collection enhancement solder ribbon 21 is in electrical contact with the conductive interconnect layer 172 so that the current collected by the current collection enhancement solder ribbon 21 flows into the interconnect solder ribbon 22.

[0107] The second aspect of this application provides a battery string 2, which is formed by connecting battery cells 1 provided in the first aspect of this application in series. A current collection enhancement main grid 13 is provided with a corresponding current collection enhancement solder strip 21. The first interconnecting main grid 1 and the second interconnecting main grid 2 of the same battery cell 1 are respectively provided with different interconnecting solder strips 22.

[0108] In the same solar cell 1, the current harvesting enhancement ribbon 21 transmits current to the interconnect ribbon 22 through the lateral conductive structure;

[0109] In two adjacently arranged solar cells 1, the first interconnecting main busbar 1 of one solar cell 1 and the second interconnecting main busbar 2 of the other solar cell 1 are electrically connected by interconnecting solder strips 22.

[0110] In some optional embodiments of the second aspect of this application, in the direction of current transmission of the solder strip, the lateral conductive structure is disposed close to the first side L, which is located at the current outflow end of the cell 1. In these embodiments, the positioning of the lateral conductive structure can help the current collected on the main grid to be efficiently and quickly transmitted to the next cell 1 through the interconnect solder strip 22, shortening the current transmission path between cells 1 in the cell string 2 and reducing transmission loss. The first side is one of the two opposite sides of the cell.

[0111] like Figure 15 and Figure 16 As shown, in some optional embodiments of the second aspect of this application, the battery string 2 adopts the following... Figure 8 The battery cells 1 shown are obtained by connecting them in series via interconnecting ribbons 22. The difference between the interconnecting ribbons 22 and the lateral conductive structure is that the interconnecting ribbons 22 are used when making the battery string, while the lateral conductive structure is formed when making the battery cells.

[0112] Figure 16 The cross-section shown is for Figure 15 The cross-section obtained by transversely cutting the battery string 2 along the transverse transmission grid line 16.

[0113] The second interconnect main grid 2 and the current collection enhancement main grid 13 collect the fine grid current and transmit it to the interconnect solder strip 22 and the current collection enhancement solder strip 21. The current on the current collection enhancement solder strip 21 is transmitted to the interconnect solder strip 22 through the lateral transmission grid line 16. The interconnect solder strip 22 is interconnected with the front side of the next cell 1 to form a cell string 2.

[0114] In some embodiments of the second aspect of this application, the width of both the interconnecting solder strip 22 and the current collection enhancement solder strip 21 is 0.18 mm to 1.5 mm, for example, 0.18 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, 1.3 mm, or 1.5 mm, and the thickness is 0.08 mm to 0.5 mm, for example, 0.08 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, or 0.5 mm, and the melting point is 130°C to 185°C, for example, 130°C, 145°C, 165°C, or 185°C. The cross-sectional shape of the interconnecting solder strip 22 and the current collection enhancement solder strip 21 includes, but is not limited to, circles, rectangles, and triangles. The cross-sectional shapes of the interconnecting solder strip 22 and the current collection enhancement solder strip 21 may be the same or different. The lateral transmission grid line 16 contacts the second interconnecting main grid 2 and the current collection enhancement main grid 13 respectively to achieve electrical connection.

[0115] In some embodiments of the second aspect of this application, the width of the interconnect solder strip 22 is greater than the width of the current collection enhancement solder strip 21, and the ratio of the width of the interconnect solder strip 22 to the width of the current collection enhancement solder strip 21 is 1.1:1 to 2:1. While reducing the manufacturing cost, the current collection capability is effectively improved by setting the current collection enhancement solder strip 21, thereby improving the battery efficiency.

[0116] like Figure 17 As shown, in some optional embodiments of the second aspect of this application, the battery string 2 adopts the following... Figure 9 The battery cell 1 shown is obtained by connecting it in series via interconnecting ribbons 22.

[0117] In these embodiments, the current-collecting enhancement solder strip 21, which is correspondingly welded onto the current-collecting enhancement main grid 13, is electrically connected to the conductive layer 17. A portion of the same interconnect solder strip 22 is correspondingly welded to the second interconnect main grid 2 on the back side of one of the two adjacent battery cells 1, and the interconnect solder strip 22 is electrically contacted with the conductive layer 17. Then, it is wound upward from the first side L of one of the two adjacent battery cells 1 to the front side of the other of the two adjacent battery cells 1 and welded to the first interconnect main grid 1 on the front side of the other of the two adjacent battery cells 1, thereby completing the series connection of the battery cells 1.

[0118] like Figure 18 As shown, in some optional embodiments of the second aspect of this application, the battery string 2 adopts the following... Figures 10 to 12 Battery strings 2 are prepared using any one of the various battery cells 1 shown. Figures 10 to 12 The battery cells 1 shown all have a conductive layer 17, which has a single-layer or double-layer structure. Figure 18 The conductive layer 17 is shown as a single layer structure. Figure 18As can be seen, both the interconnecting ribbon 22 and the current harvesting enhancement ribbon 21 are electrically connected to the conductive layer 17. The conductive layer 17 transfers the current from the current harvesting enhancement ribbon 21 to the interconnecting ribbon 22 and interconnects with the next solar cell 1. The conductive layer 17 is located between the main busbar and the ribbon. Figure 18 The cross-section of battery string 2 is a cross-section obtained by transversely cutting one of the battery cells 1 along the first side L of battery string 2. The following... Figures 19 to 23 The cross section of battery string 2 is also the cross section obtained by transversely cutting one of the battery cells 1 of battery string 2 along the first side L.

[0119] like Figure 19 As shown, in some optional embodiments of the second aspect of this application, the battery string 2 adopts the following... Figure 14 The battery string 2 is fabricated in the shown battery cell 1. On the back side of the battery string 2, interconnecting solder ribbons 22 are soldered to the corresponding second interconnecting main grid 2, and the portion of the interconnecting solder ribbons 22 near the first side L of the battery cell 1 is electrically connected to the conductive layer electrical transport portion 17a. The conductive layer electrical transport portion 17a includes a single conductive interconnecting layer 172 or includes a stacked conductive adhesive layer 171 and conductive interconnecting layers 172. Current harvesting enhancement solder ribbons 21 are soldered to the corresponding current harvesting enhancement main grid 13, and the portion of the current harvesting enhancement solder ribbons 21 near the first side L of the battery cell 1 is electrically connected to the conductive layer electrical transport portion 17a.

[0120] Figure 14 The conductive layer 17 of the shown battery cell 1 includes a buffer layer 173. For example... Figure 19 The portions of the interconnecting solder ribbon 22 near the first side L of the cell 1 and the portions of the current collection enhancement solder ribbon 21 near the first side L of the cell 1 are alternately arranged in the intervals between two adjacent buffer blocks on the buffer layer 173. In some examples, the height of the buffer layer 173 is consistent with the height of the interconnecting solder ribbon 22, reducing the risk of microcracks caused by the height difference between the interconnecting solder ribbon 22 and the back surface of the cell 1 during the formation of the cell string 2, thus ensuring current collection efficiency. Furthermore, the height of the current collection enhancement solder ribbon 21 is also consistent with the height of the buffer layer 173, which can further reduce the risk of microcracks caused by uneven stress at the edge of the cell 1.

[0121] like Figure 20 As shown, in another example of the embodiments of the second aspect of this application, in some optional embodiments of the second aspect of this application, the battery string 2 adopts as follows: Figure 13 The battery string 2 is fabricated in the battery cell 1 shown.

[0122] In some examples of these embodiments, the top of the current-harvesting enhancement solder strip 21 abuts against the corresponding buffer protection block 1731, and the lower part of the end where the current-harvesting enhancement solder strip 21 and the buffer protection block 1731 abut against the contact is electrically connected to the conductive layer electrical transport portion 17a, that is, in Figure 20When an observer looks at the cross-section of the battery string 2 from the first side L of the battery cell 1, only the buffer protection block 1731 can be seen. Therefore, the current collection enhancement solder strip 21 is indicated by a white dashed line.

[0123] In other examples of these embodiments, the current-harvesting enhanced solder strip 21 is electrically connected to the conductive layer electrical transport portion 17a below the end facing the first side L, and a buffer protection block 1731 is wrapped around the outer periphery of the end of the current-harvesting enhanced solder strip 21 facing the first side L. That is, in Figure 20 An observer looking at the cross-section of the battery string 2 from the first side L of the battery cell 1 can only see the buffer protection block 1731 or the buffer protection block 1731 wrapping the current collection enhancement solder ribbon 21. Therefore, the current collection enhancement solder ribbon 21 is indicated by a white dashed line. The buffer protection block 1731 is set at the same height as the interconnect solder ribbon 22.

[0124] like Figure 21 As shown, the second aspect of this application provides a battery string 2, which adopts the method described in this application. Figure 13 or Figure 14 The solar cells 1 are connected in series. The back of one of the two adjacent solar cells 1 overlaps the front of the other solar cell 1 through its own conductive layer 17, achieving negative-pitch series connection. The interconnecting ribbon 22 does not need to wrap from the front of one solar cell 1 to the back of the other solar cell 1 for series connection. The interconnecting ribbon extends from the front of one adjacent solar cell 1 through the conductive layer 17 to the back of the other adjacent solar cell 1, shortening the required length of the interconnecting ribbon 22. Figure 9 The first pad row, which is located near the first side L, is moved outward, so that the conductive layer 17 has a better electrical contact effect on the first pad row and reduces current transmission loss.

[0125] like Figure 22 As shown, a third aspect of this application also provides a battery string 2. The battery string 2 adopts the method described in this application. Figure 6 and Figure 7 The battery cells 1 shown are connected in series. Current collection enhancement main grid 13 is welded with current collection enhancement solder ribbon 21. The first interconnect main grid 1 and the second interconnect main grid 2 of the same battery cell 1 are respectively welded with different interconnect solder ribbons 22. Multiple current collection enhancement solder ribbons 21 and multiple interconnect solder ribbons 22 form a solder ribbon layer on the back side of the battery cell 1.

[0126] A connecting solder strip 23 is provided on the side of the solder strip layer facing away from the second main gate layer. The connecting solder strip 23 extends laterally and is electrically connected to each current collection enhancement solder strip 21 and each interconnecting solder strip 22 in the solder strip layer.

[0127] In some optional embodiments of the third aspect of this application, in the direction of solder ribbon current transmission, the connecting solder ribbon 23 is disposed close to the first side L, and the first side L is located at the current outflow end of the cell 1. The connecting solder ribbon 23 is disposed corresponding to the first pad row close to the first side L, which facilitates the efficient transmission of the current collected by the current collection enhancement solder ribbon 21 to the interconnecting solder ribbon 22, and then the rapid transmission of current between the cells 1, thereby reducing current transmission loss.

[0128] In some optional embodiments of the third aspect of this application, the width of the connecting solder strip 23 is 0.5mm to 2mm, for example, 0.5mm, 1mm, 1.5mm, or 2mm, and the thickness of the connecting solder strip 23 is 10μm to 100μm, for example, 10μm, 30μm, 60μm, 80μm, or 100μm. The connecting solder strip 23 is disposed on the second main grid layer by welding. The connecting solder strip 23 is a tin-plated copper strip. In these embodiments, the interconnecting solder strip 22 and the current collection enhancement solder strip 21 on the battery cell 1 in the battery string 2 are electrically connected by welding the connecting solder strip 23 after the battery string 2 is formed.

[0129] The fourth aspect of this application provides a method for preparing a battery string 2, wherein the battery string 2 is the same as the battery string 2 of the second aspect of this application, comprising:

[0130] First, the current collection enhancement solder ribbon 21 and the interconnection solder ribbon 22 are laid on the back of the battery cell 1 on the stringing equipment. Then, the battery cell 1 is laid face down on the current collection enhancement solder ribbon 21 and the interconnection solder ribbon 22.

[0131] like Figure 24 As shown, the specific method and process include:

[0132] S10: Lay the current collection enhancement solder ribbon 21 of the first battery cell 1 at the starting position of the battery string 2 and lay the interconnection solder ribbon 22 on the back of the first battery cell 1 on the stringing equipment. The laying order of the current collection enhancement solder ribbon 21 and the interconnection solder ribbon 22 can be interchanged in this step.

[0133] In some specific examples, the laying process uses a traction mechanism to place the cut welding strips in a designated location.

[0134] S11: Lay out the first solar cell 1;

[0135] S12: Lay the current collection enhancement solder ribbon 21 of the second battery cell 1 on the side of the first battery cell 1 (the side opposite to the first side L of the battery cell 1), lay the interconnection solder ribbon 22 of the second battery cell 1, part of the interconnection solder ribbon 22 of the second battery cell 1 is in the same layer as the current collection enhancement solder ribbon 21 of the second battery cell 1, that is, it is set on the back of the second battery cell 1, and the other part is set on the front of the first battery cell 1 to electrically connect the first battery cell 1 and the second battery cell 1, and then lay the second battery cell 1.

[0136] S14: Repeat step S12 above to lay the remaining battery cells 1 in the battery string 2 on the side of the second battery cell 1 (the side opposite to the first side L of the battery cell 1) until the battery string 2 is laid down. The end battery cell 1 of the battery string 2 is laid down, and the interconnecting solder strip 22 is laid on the front side of the end battery cell 1.

[0137] The solder ribbon can be laid completely before infrared welding, or welding can be performed while laying the solder ribbon. The welding process uses infrared welding. During welding, tooling is pressed onto the solder ribbon on the front side of the solar cell 1 to fix the solder ribbon. Infrared lamps (tungsten halogen lamps or ceramic heating tubes) emit infrared rays with a wavelength of 800-1500nm to directly heat the contact area between the solder ribbon and the grid line of the solar cell 1, causing the solder to melt and form a connection to complete the fabrication of the solar cell string 2.

[0138] The fourth aspect of this application provides another method for preparing a battery string 2, wherein the battery string 2 is the same as the battery string 2 of the second aspect of this application, comprising:

[0139] A current collection enhancement ribbon 21 is laid and fixed on the back of the cell 1. An interconnect ribbon 22 is laid on the stringing equipment. The cell 1 with the current collection enhancement ribbon 21 laid on it is laid on the interconnect ribbon 22 with the back side facing down.

[0140] The fourth aspect of this application provides a method for preparing a battery string 2, wherein the battery string 2 is the same as the battery string 2 of the second aspect of this application, comprising:

[0141] Interconnecting solder ribbons 22 and battery cells 1 are alternately laid on a stringing equipment to form a pre-connected battery string. Current collection enhancement solder ribbons 21 are laid and fixed on the back of each battery cell 1 in the pre-connected battery string.

[0142] like Figure 25 As shown, in some examples of these embodiments, the battery cell 1 is as follows: Figure 9 The battery cell 1 shown has a conductive layer 17. The specific manufacturing method of the battery string 2 includes:

[0143] S20: With the back side of the solar cell 1 facing upwards, a fixing adhesive is printed at the current collection enhancement grid 13 position. The fixing adhesive includes, but is not limited to, thermosetting adhesive and UV adhesive. The number of adhesive dots 3 is 3-12, for example, 3, 5, 7, 9, or 12; the shape of the adhesive dots 3 includes, but is not limited to, circular or rectangular; the area of ​​the adhesive dots 3 is 0.5 mm². 2 ~2mm 2 For example, it can be 0.5mm. 2 1mm 2 1.5mm 2 or 2mm 2 The adhesive height ranges from 5μm to 50μm, for example, it can be 5μm, 10μm, 20μm, 30μm, 40μm or 50μm, etc.

[0144] S21: A current collection enhancement welding ribbon 21 is laid on the back of the battery cell 1. The current collection enhancement welding ribbon 21 is fixed by a curing process, and the battery cell 1 is flipped so that the front side is facing up and the back side is facing down, which is consistent with the feeding method of conventional string welding.

[0145] S22: Lay the interconnecting ribbon 22 on the back of the first cell 1 on the stringing equipment.

[0146] S23: The first battery cell 1 processed in step S21 is laid face down on its corresponding interconnection ribbon 22;

[0147] S24: Lay the interconnecting ribbon 22 of the second battery cell 1 on the side of the first battery cell 1 (the side opposite to the first side L of the battery cell 1). Part of the interconnecting ribbon 22 of the second battery cell 1 is laid on the stringing equipment, and this part is set on the back of the second battery cell 1. The other part of the interconnecting ribbon 22 of the second battery cell 1 is set on the front of the first battery cell 1 to electrically connect the first battery cell 1 and the second battery cell 1. Then lay the second battery cell 1 processed in step S21.

[0148] S25: Repeat steps S22 to S24 above to lay the remaining battery cells 1 in the battery string 2 on the side of the second battery cell 1 (the side opposite to the first side L of the battery cell 1) until the end battery cell 1 of the battery string 2 is laid. The interconnecting solder strip 22 is laid on the front side of the end battery cell 1 to complete the fabrication of the battery string 2.

[0149] In these examples, the welding strips can be laid completely before infrared welding is performed, or the welding strips can be laid and welded simultaneously.

[0150] In other examples of these embodiments, the battery cell 1 is as follows: Figure 9 The battery cell 1 shown has a conductive layer 17. The specific manufacturing method of the battery string 2 (not shown in the figure) includes:

[0151] S30: Lay the interconnecting ribbon 22 on the back of the first cell 1 on the stringing equipment;

[0152] S31: Lay the first battery cell 1 with its back side facing down on the corresponding interconnecting ribbon 22;

[0153] S32: The interconnecting ribbon 22 of the second battery cell 1 is laid on the side of the first battery cell 1 (the side opposite to the first side L of the battery cell 1). Part of the interconnecting ribbon 22 of the second battery cell 1 is laid on the stringing equipment. This part is set on the back of the second battery cell 1. The other part of the interconnecting ribbon 22 of the second battery cell 1 is set on the front of the first battery cell 1 to electrically connect the first battery cell 1 and the second battery cell 1. Then the second battery cell 1 is laid.

[0154] S33: On the side of the second battery cell 1 (the side opposite to the first side L of battery cell 1), repeat the above steps S22 to S24 to lay the remaining battery cells 1 in the battery string 2 until the end battery cell 1 of the battery string 2 is laid. The interconnecting solder strip 22 is laid on the front side of the end battery cell 1 to complete the fabrication of the pre-connected battery string.

[0155] S34: Adhesive is printed and fixed at the current collection enhancement grid 13 position on the back of each cell in the pre-connected battery string. The adhesive includes, but is not limited to, thermosetting adhesive and UV adhesive; the number of adhesive dots 3 is 3-12; the shape of the adhesive dots 3 includes, but is not limited to, circular or rectangular; the area of ​​the adhesive dots 3 is 0.5 mm². 2 ~2mm 2 The adhesive height is 5μm to 50μm; a current collection enhancement welding ribbon 21 is laid at the corresponding position of the current collection enhancement grid 13 on the back of each battery cell 1, and the current collection enhancement welding ribbon 21 is fixed by the curing process to complete the fabrication of the battery string 2.

[0156] For detailed steps in the above example, please refer to... Figure 27 ,and Figure 27 The difference in the process is that the battery cell 1 already has a conductive layer 17 (lateral conductive structure), so there is no need to weld the connecting strip 23.

[0157] The fifth aspect of this application provides a method for preparing a battery string 2, wherein the battery string 2 is the same as the battery string 2 of the third aspect of this application, comprising:

[0158] First, a connecting ribbon 23 is laid on the stringing equipment. Then, a current collection enhancement ribbon 21 and an interconnecting ribbon 22 are laid on the connecting ribbon 23. Finally, the battery cell 1 is laid face down on the current collection enhancement ribbon 21 and the interconnecting ribbon 22; or,

[0159] Interconnecting solder ribbons 22 and battery cells 1 are alternately laid on a stringing equipment to form a pre-connected battery string. Current collection enhancement solder ribbons 21 are laid and fixed on the back of each battery cell 1 in the pre-connected battery string. Connecting solder ribbons 23 are laid on the current collection enhancement solder ribbons 21 and interconnecting solder ribbons 22.

[0160] like Figure 26 As shown, in some optional embodiments of the fifth aspect of this application, a connecting ribbon 23 is first laid on the stringing equipment, then a current-collecting enhancement ribbon 21 and an interconnecting ribbon 22 are laid on the connecting ribbon 23, and then the battery cell 1 is laid face down on the current-collecting enhancement ribbon 21 and the interconnecting ribbon 22, and the battery string 2 is as follows. Figure 23 The battery string 2 shown in the figure has battery cell 1 as shown in the figure. Figure 6 The specific method for the battery cell 1 shown includes:

[0161] S40: Lay the connecting ribbon 23 of the first battery cell 1 on the stringing equipment;

[0162] S41: Lay the current collection enhancement solder strip 21 of the first cell 1 and the interconnection solder strip 22 on the back of the first cell 1 on the connecting solder strip 23.

[0163] S42: Lay the first battery cell 1 on each of the welding strips of the first battery cell 1 that have been laid in steps S40 and S41;

[0164] S43: A connecting ribbon 23 of the second battery cell 1 is laid on the side of the first battery cell 1 (the side opposite to the first side L of the battery cell 1). A current collection enhancement ribbon 21 of the second battery cell 1 and an interconnecting ribbon 22 on the back of the second battery cell 1 are laid on the connecting ribbon 23 of the second battery cell 1. A portion of the interconnecting ribbon 22 of the second battery cell 1 is laid on the stringing equipment and this portion is set on the back of the second battery cell 1. The other portion of the interconnecting ribbon 22 of the second battery cell 1 is set on the front of the first battery cell 1 to electrically connect the first battery cell 1 and the second battery cell 1. Then the second battery cell 1 is laid.

[0165] S44: Repeat steps S40 to S43 above to lay the remaining battery cells 1 in the battery string 2 on the side of the second battery cell 1 (the side opposite to the first side L of the battery cell 1) until the end battery cell 1 of the battery string 2 is laid. The interconnecting solder strip 22 is laid on the front side of the end battery cell 1 to complete the fabrication of the battery string 2.

[0166] like Figure 27As shown, in some optional embodiments of the fifth aspect of this application, interconnecting solder ribbons 22 and battery cells 1 are alternately laid on a stringing equipment to form a pre-connected battery string. Current collection enhancement solder ribbons 21 are laid and fixed on the back of each battery cell 1 in the pre-connected battery string. Connecting solder ribbons 23 are laid on the current collection enhancement solder ribbons 21 and the interconnecting solder ribbons 22. The battery string 2 is as follows: Figure 23 The battery string 2 shown in the figure has battery cell 1 as shown in the figure. Figure 6 The specific method for the battery cell 1 shown includes:

[0167] S50: Lay out the interconnecting ribbon 22 on the back of the first cell 1 on the stringing equipment;

[0168] S51: Lay the first cell 1 on the interconnecting ribbon 22;

[0169] S52: The interconnecting ribbon 22 of the second battery cell 1 is laid on the side of the first battery cell 1 (the side opposite to the first side L of the battery cell 1). Part of the interconnecting ribbon 22 of the second battery cell 1 is laid on the stringing equipment. This part is set on the back of the second battery cell 1. The other part of the interconnecting ribbon 22 of the second battery cell 1 is set on the front of the first battery cell 1 to electrically connect the first battery cell 1 and the second battery cell 1. Then the second battery cell 1 is laid.

[0170] S53: Repeat steps S50 to S52 to complete the pre-connected battery string;

[0171] S54: Apply a fixing adhesive to the current collection enhancement grid 13 position on the back of the pre-connected battery string. The fixing adhesive includes, but is not limited to, thermosetting adhesive and UV adhesive, with 3-12 adhesive dots 3; the shape of the adhesive dots 3 includes, but is not limited to, circular or rectangular; the area of ​​the adhesive dots 3 is 0.5 mm². 2 ~2mm 2 The adhesive height is 5μm to 50μm; a current collection enhancement welding ribbon 21 is laid at the corresponding position of the current collection enhancement grid 13 on the back of each battery cell 1, and the current collection enhancement welding ribbon 21 is fixed by a curing process.

[0172] S55: Lay and weld the connecting ribbon 23 on the current collection enhancement ribbon 21 and the back interconnect ribbon 22 of each battery cell 1 near the first side L position to complete the fabrication of the battery string 2.

[0173] The sixth aspect of this application provides a photovoltaic module, which includes a battery string 2 of the second and / or third aspects of this application.

[0174] The photovoltaic module provided in the sixth aspect of this application reduces the optical loss on the front side of the photovoltaic module. Furthermore, by setting a current collection enhancement grid 13 and a corresponding current collection enhancement solder strip 21 on the back side of the cell 1 to enhance current collection function, the current loss of the photovoltaic module is reduced and the fill factor of the photovoltaic module is improved. The fill factor can be improved by 0.2% to 2%, thereby achieving a power gain of about 1W to 12W in the photovoltaic module and obtaining a high-power photovoltaic module.

Claims

1. A battery cell, characterized in that, The solar cell has a front side and a back side. The front side has a first main grid layer, which includes a plurality of first interconnect main grids spaced apart. The back side has a second main grid layer, which includes a plurality of second interconnect main grids and a plurality of current collection enhancement main grids. The plurality of first interconnecting main gates and the plurality of second interconnecting main gates are arranged in a one-to-one correspondence in the thickness direction of the solar cell, and at least one current collection enhancement main gate is provided on both sides of each first interconnecting main gate.

2. The battery cell according to claim 1, characterized in that, The same number of current collection enhancement main gates are respectively provided on both sides of each of the first interconnect main gates; Preferably, a plurality of current harvesting enhancement main gates are provided between two adjacent second interconnecting main gates, and the plurality of current harvesting enhancement main gates are evenly spaced. Preferably, the second interconnecting main grid has harpoon lines with openings facing the edge of the cell at both ends, and at least one end of the current collection enhancement main grid extends in a straight line along its own length to the edge of the cell.

3. The battery cell according to claim 1, characterized in that, The solar cell includes a lateral conductive structure disposed on the back side, and a plurality of second interconnect main grids and a plurality of current harvesting enhancement main grids are electrically connected in the lateral direction through the lateral conductive structure, the lateral direction being perpendicular to the extension direction of the second interconnect main grids; Preferably, in the extension direction of the second interconnecting main grid, the lateral conductive structure is disposed close to the first side, which is one of the two opposite sides of the battery cell; Preferably, the distance between the transverse conductive structure and the first side is 0.1mm-2mm; Preferably, the battery cell is a half-cell battery cell, and the first side has a cut surface; Preferably, both the second interconnect main gate and the current harvesting enhancement main gate are provided with a plurality of pads spaced apart along their respective extension directions. In the lateral direction, the plurality of pads are spaced apart and aligned in rows to form a pad row. In the thickness direction of the cell, the lateral conductive structure contacts and covers the pad row closest to the first side. Preferably, the distance between the pad row closest to the first side and the first side is 0.1mm to 2mm; Preferably, the lateral conductive structure includes a lateral transmission gate line disposed on the back side and in the same layer as the second gate line layer, and a plurality of second interconnect main gates and a plurality of current harvesting enhancement main gates are electrically connected in the lateral direction through the lateral transmission gate line; Preferably, the lateral transmission gate line includes a plurality of lateral transmission segments, and each lateral transmission segment is connected at both ends to two adjacent current collection enhancement main gates, or to adjacent current collection enhancement main gates and the second interconnecting main gate; Preferably, the thickness of the transverse transmission grid line is 5-50 μm and the width is 20-2000 μm; Preferably, the lateral transmission gate line is made of copper wire, and the width of the lateral transmission gate line is 500-2000 μm; Preferably, the length of the lateral transmission gate line is equal to the spacing between the two furthest current collection enhancement main gates in the lateral direction.

4. The battery cell according to claim 3, characterized in that, The lateral conductive structure includes a conductive layer, which is disposed on the side of the second main gate layer opposite to the first main gate layer and is electrically connected to the second interconnect main gate and the current collection enhancement main gate. Preferably, in the lateral direction, the length of the conductive layer is greater than the spacing between the two furthest current collection enhancement main grids and less than the spacing between the two opposite sides of the solar cell. Preferably, the conductive layer is elongated, and in the extension direction of the second interconnecting main gate, the width of the conductive layer is less than half the width of the battery cell, and one long side of the conductive layer is aligned with the first side. Preferably, the conductive layer is a single-layer structure and is made of conductive adhesive; preferably, the width of the conductive layer is 0.5 mm to 2 mm and the thickness of the conductive layer is 5 to 200 μm.

5. The battery cell according to claim 4, characterized in that, The conductive layer includes a conductive adhesive layer and a conductive interconnect layer stacked on the second main gate layer. The conductive interconnect layer is continuously laid on the conductive adhesive layer along the transverse direction. The conductive interconnect layer is bonded to and electrically connected to the second main gate layer through the conductive adhesive layer. Preferably, the conductive adhesive layer is made of conductive adhesive, the width of the conductive adhesive layer is 0.5mm to 2mm, and the thickness of the conductive adhesive layer is 5μm to 200μm; the conductive interconnect layer is made of conductive metal material, the width of the conductive interconnect layer is 0.5mm to 2mm, and the thickness of the conductive interconnect layer is 10μm to 100μm. Preferably, the conductive adhesive layer includes a plurality of spaced adhesive blocks, and each of the second interconnect main gates and each of the current harvesting enhancement main gates is correspondingly provided with an adhesive block. Alternatively, in the lateral direction, the conductive adhesive layer is continuously laid on the second main gate layer, and the conductive adhesive layer is bonded to each of the second interconnect main gates and each of the current collection enhancement main gates; Preferably, the conductive layer further includes a buffer layer disposed on the side of the conductive interconnect layer opposite to the conductive adhesive layer, the buffer layer including a plurality of buffer protection blocks spaced apart, the interval between two adjacent buffer protection blocks corresponding to at least one second interconnect main gate; Preferably, the conductive layer further includes a buffer layer disposed on the side of the conductive interconnect layer opposite to the conductive adhesive layer, the buffer layer including a plurality of buffer protection blocks spaced apart, the spacing between two adjacent buffer protection blocks corresponding one-to-one with the main gate spacing formed in the second main gate layer; Preferably, the buffer protection block is made of polyolefin polymer material or conductive metal material.

6. A battery string, characterized in that, The battery string is formed by connecting battery cells in series as described in any one of claims 1 to 5. Current collection enhancement strips are correspondingly provided on the current collection enhancement main grid. Different interconnecting strips are respectively provided on the first interconnecting main grid and the second interconnecting main grid of the same battery cell. In the same solar cell, the current-collecting enhancement solder strip transmits current to the interconnect solder strip through the lateral conductive structure; In two adjacently arranged solar cells, the first interconnecting main grid of one solar cell and the second interconnecting main grid of the other solar cell are electrically connected by interconnecting strips. Preferably, in the direction of current transmission of the solder strip, the transverse conductive structure is disposed close to the first side, which is one of the two opposite sides of the battery cell.

7. A battery string, characterized in that, The battery string is formed by connecting battery cells as described in claim 1 or 2. Current collection enhancement solder strips are welded on the current collection enhancement grid. The first interconnect grid and the second interconnect grid of the same battery cell are respectively welded with different interconnect solder strips. Multiple current collection enhancement solder strips and multiple interconnect solder strips form a solder strip layer on the back side of the battery cell. A connecting solder strip is provided on the side of the solder strip layer facing away from the second main gate layer. The connecting solder strip extends in the lateral direction and is electrically connected to each of the current collection enhancement solder strips and each of the interconnecting solder strips in the solder strip layer. Preferably, the width of the connecting solder strip is 0.5mm to 2mm, and the thickness of the connecting solder strip is 10μm to 100μm; Preferably, in the direction of current transmission of the solder strip, the connecting solder strip is disposed close to the first side, which is one of the two opposite sides of the battery cell.

8. A method for preparing a battery string as described in claim 6, characterized in that, include: First, the current-collecting enhancement solder strip and the interconnection solder strip are laid on the stringing equipment, and then the battery cell is laid face down on the current-collecting enhancement solder strip and the interconnection solder strip; or, The current-collecting enhancement solder ribbon is laid and fixed on the back side of the solar cell, and the interconnect solder ribbon is laid on the stringing equipment. The solar cell with the current-collecting enhancement solder ribbon already laid on it is placed on the interconnect solder ribbon with its back side facing down; or... The interconnecting solder ribbons and the battery cells are alternately laid on the stringing equipment to form a pre-connected battery string. The current collection enhancement solder ribbon is laid and fixed on the back of each battery cell in the pre-connected battery string.

9. A method for preparing a battery string as described in claim 7, characterized in that, include: First, a connecting solder strip is laid on the stringing equipment. Then, the current collection enhancement solder strip and the interconnecting solder strip are laid on the connecting solder strip. The battery cell is then laid face down on the current collection enhancement solder strip and the interconnecting solder strip. Alternatively, the interconnecting solder strip and the battery cell are alternately laid on the stringing equipment to form a pre-connected battery string. The current collection enhancement solder strip is laid and fixed on the back of each battery cell in the pre-connected battery string. The connecting solder strip is then laid on the current collection enhancement solder strip and the interconnecting solder strip.

10. A photovoltaic module, characterized in that, Includes the battery string as claimed in claim 9 or 10.

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