A back contact stacked gate cell assembly

Abstract

The application discloses a back contact stacked gate battery assembly, which comprises at least two battery units arranged along a first direction, the battery unit comprising a battery sheet body and a positive current transmission structure and a negative current transmission structure arranged on the back of the battery sheet body; the positive current transmission structure and the negative current transmission structure each comprise a linear conductive element for collecting photo-generated carriers; wherein any one of the positive current transmission structure or the negative current transmission structure of each battery unit has a cantilever part with the same end of the linear conductive element exceeding the edge of the battery sheet body; the adjacent two battery units are conducted through the linear conductive element, forming a stacked series battery assembly. The application replaces the traditional silver paste grid line with the linear conductive element, so that the silver consumption is reduced, the process is simplified, meanwhile, the test point position is extended, and the test sorting efficiency and reliability are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of solar crystalline silicon cells and photovoltaic modules, and specifically relates to a back-contact stacked grid cell module. Background Technology

[0002] Solar crystalline silicon cells are the core components of the photovoltaic industry. Their electrode structure directly determines the cell's photoelectric conversion efficiency, manufacturing cost, and module packaging compatibility. Traditional crystalline silicon cells have the positive and negative electrodes located on opposite sides of the cell. The metal grid lines on the front side block incident light, resulting in significant optical loss and limiting efficiency improvements. Fully back-contact (BC) cells integrate both positive and negative electrodes on the back of the cell, eliminating any metal obstruction on the light-receiving surface. This effectively improves short-circuit current and conversion efficiency, making it one of the mainstream technologies for high-efficiency crystalline silicon cells.

[0003] Existing conventional bifacial photovoltaic (BC) cells employ a metallized structure on the back side with a main grid and a sub-grid, with the positive and negative electrode areas arranged alternately. The sub-grid collects current and then directs it to the main grid, ultimately achieving cell interconnection via solder ribbons welded to the main grid. This structure has several inherent drawbacks: Firstly, both the main and sub-grids are fabricated using silver paste screen printing, and the high cost of silver contributes to high manufacturing costs. Furthermore, the complex grid pattern design not only increases the manufacturing difficulty but also increases the risk of leakage, short circuits, and other defects, making it difficult to guarantee product yield. Secondly, the large area of ​​metal grid lines causes severe shading on the back of the cell, significantly reducing the bifacial power generation capacity of the BC cell module and failing to meet the current market demand for bifacial photovoltaic modules. In addition, the current transmission path formed by the main and sub-grids has significant resistance losses, easily leading to localized blackening of the electroluminescence (EL) layer, affecting the overall performance and lifespan of the cell.

[0004] With the continuous development of photovoltaic technology, stacked busbar metallization technology has been gradually applied. This structure uses an ultra-thin current collection layer combined with conductive wires to replace traditional grid lines, and can use base metal materials instead of silver paste. It has the advantages of low shading, low loss, and low cost. However, stacked busbar technology has not yet been deeply integrated with BC cells. At the same time, in order to improve the power density of modules, the industry generally adopts the stacking packaging process to eliminate the gaps between cells. However, traditional BC cells are limited by the back electrode layout and main busbar structure, which makes it impossible to achieve stable stacking interconnection, becoming a major obstacle to the large-scale application of high-power BC cell modules.

[0005] In addition, the electrode contacts of traditional grid-connected (BC) cells are hidden in the grid area on the back of the cell. During cell sorting and electrical performance testing, it is difficult for probes to accurately align with the electrodes, resulting in cumbersome and inefficient testing operations. Existing grid-less BC cell solutions often achieve interconnection through laser slicing of the entire cell and staggered grid protrusion. This not only requires additional laser cutting processes but also demands a one-to-one correspondence between the positive and negative grid lines, resulting in poor electrode design flexibility. Furthermore, they still rely on printed grid structures, limiting the back-side light-shielding and silver-reducing effects. In summary, existing BC cells and modules still have significant shortcomings in terms of cost, efficiency, bifaciality, packaging compatibility, and testing convenience, urgently requiring a novel structural solution to address these issues.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a back-contact stacked grid battery assembly, thereby overcoming the defects in the prior art.

[0008] To achieve the above objectives, the present invention provides a back-contact stacked grid battery assembly, including at least two battery cells arranged along a first direction. The battery cell includes a battery cell body and a positive current transmission structure and a negative current transmission structure disposed on the back side of the battery cell body. Both the positive current transmission structure and the negative current transmission structure include a linear conductive element for collecting photogenerated charge carriers. In each battery cell, either the positive or negative current transmission structure has a cantilever portion extending beyond the edge of the battery cell body at the same end of its linear conductive element. The two adjacent battery cells are connected by a linear conductive element to form a stacked series battery assembly.

[0009] Preferably, the battery cell includes a first type of battery and a second type of battery. The back of the first type of battery is arranged alternately in parallel with the positive current transmission structure and the negative current transmission structure in that order. The back of the second type of battery is arranged alternately in parallel with the negative current transmission structure and the positive current transmission structure in that order.

[0010] Preferably, the battery assembly is formed by alternating stacking and series connection of a first type of battery and a second type of battery.

[0011] Preferably, the battery assembly is formed by stacking and connecting a single type of battery, either a first type or a second type, in series.

[0012] Preferably, each battery cell further includes a conductive connection structure, and all of the cantilever portion is connected to the conductive connection structure, and the two connected battery cells are connected through the conductive connection structure.

[0013] Preferably, the linear conductive element is a rigid conductive connector or a flexible conductive connector.

[0014] Preferably, the conductive connection structure has a spaced insulating structure located between two connected cantilever portions.

[0015] Preferably, the length of the cantilever is 0.5-5mm.

[0016] Preferably, the overlap width of two adjacent battery cells is 0.1-2 mm.

[0017] Compared with the prior art, one aspect of the present invention has the following beneficial effects: (1) This invention abandons the expensive and complex screen printing silver paste process of traditional BC batteries and uses linear conductive elements as current collection carriers, which significantly reduces the consumption of precious metals and the difficulty of metallization pattern design. At the same time, this structure greatly reduces the metal light-shielding area on the back of the battery, effectively improving the light reflectivity and light-receiving ability on the back of the module, thereby significantly improving the bifaciality of the module and the overall power generation gain while ensuring low-cost manufacturing. (2) By bringing out the electrodes of a single cell, the present invention achieves electrical connection directly through stacking during interconnection, which solves the problem that traditional BC cells cannot achieve stable stacking due to back solder strips or grid lines blocking the connection. It eliminates the physical gap between cells, and the interconnection structure does not occupy the effective light-receiving area and does not affect the current collection in the overlapping area, which can greatly improve the power density and packaging compatibility of the module. (3) The present invention leads out the electrodes of a single battery cell and combines them with a conductive connection structure, which can extend the test contact point of the battery cell to outside the battery cell body. Contact testing can be performed at the edge or outer area of ​​the battery cell, without having to search for tiny contact points in the complex grid area on the back of the battery. The operation is simple and the positioning is accurate, which can improve the efficiency and reliability of battery sorting and electrical performance testing. (4) This invention breaks the strict limitation that the number of positive and negative grid lines must correspond one-to-one in the traditional BC interconnection scheme. The number of positive and negative conductive wires can be designed independently according to the current transmission requirements inside the battery and do not interfere with each other. This asymmetrical electrode layout capability provides great flexibility for the optimization of battery structure, which helps to further balance resistance loss and light shading loss and achieve the optimal battery performance. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the first type of battery according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the second type of battery according to Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of battery cells stacked and connected in series according to Embodiment 1 of the present invention; Figure 4 This is a three-dimensional schematic diagram of the battery cell according to Embodiment 1 of the present invention; Figure 5 This is a schematic diagram showing the distribution of the insulating layer in the conductive connection structure of Embodiment 1 of the present invention; Figure 6 This is a schematic diagram of battery cells stacked and connected in series according to Embodiment 2 of the present invention; Figure 7 This is a schematic diagram of battery cells stacked and connected in series according to Embodiment 3 of the present invention; 10-Battery cell, 10A-Type 1 battery, 10B-Type 2 battery, 101-Battery cell body, 102-Positive current transmission structure, 103-Negative current transmission structure, 104-Cantilever, 105-Conductive connection structure, 106-Insulating layer, 107-Connecting line, 20-Connection point. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0020] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0021] Example 1

[0022] like Figures 1-5 As shown, a back-contact stacked grid battery assembly includes at least two battery cells 10 arranged along a first direction. Each battery cell 10 includes a battery cell body 101 and a positive current transmission structure 102 and a negative current transmission structure 103 disposed on the back side of the battery cell body 101. Both the positive current transmission structure 102 and the negative current transmission structure 103 include a linear conductive element for collecting photogenerated carriers. The linear conductive element is made of a metal conductive wire. In each battery cell 10, the same end of the linear conductive element of either the positive current transmission structure 102 or the negative current transmission structure 103 has a cantilever portion 104 extending beyond the edge of the battery cell body 101. The two adjacent battery cells 10 are connected through the linear conductive element to form a stacked series battery assembly.

[0023] The battery unit 10 includes a first type battery 10A and a second type battery 10B. The back of the first type battery 10A is arranged alternately in parallel with the positive current transmission structure 102 and the negative current transmission structure 103 in that order. The back of the second type battery 10B is arranged alternately in parallel with the negative current transmission structure 103 and the positive current transmission structure 102 in that order. The battery assembly is formed by alternatingly stacking and connecting the first type battery 10A and the second type battery 10B.

[0024] In this case, more specifically, the cantilever portion 104 of both the first type battery 10A and the second type battery 10B is formed by a metal conductive wire at one end of the positive electrode current transmission structure 102 extending to the edge of the battery cell body, with an extension length of 0.5-5mm; the metal conductive wire at the other end is flush with the edge of the battery cell body or recessed into the edge of the battery cell body by 0.5-5mm; the metal conductive wires at both ends of the negative electrode current transmission structure 103 are flush with the edge of the battery cell body or recessed into the edge of the battery cell body by 0.5-5mm.

[0025] In this case, the battery unit 10 further includes a conductive connection structure 105. The cantilever portion 104 is completely connected to the conductive connection structure 105. The two connected battery units 10 are connected through the conductive connection structure 105. The conductive connection structure 105 adopts a conductive connecting strip. The conductive connection structure 105 is also provided with insulating layers 106 at intervals. When the two battery units are stacked and interconnected, the conductive connection structure 105 of one battery unit is connected to the negative current transmission structure 103 of the adjacent battery unit to achieve conduction (the connection position is recorded as connection point 20). The insulating layer 106 can separate the conductive connection structure 105 from the positive current transmission structure 102 of the adjacent battery unit to avoid short circuit. The stacking width of the two adjacent battery units is 0.1-2mm.

[0026] This design differentiates the positions of the conductive wires at the two poles: the positive pole is exposed outside the cell body, while the negative pole is completely recessed or flush with the surface. During stacking and interconnection, only the conductive connecting strip that overlaps with the exposed cantilever portion 104 of the positive pole is used to achieve conduction with the negative pole of the adjacent cell, preventing unintentional bridging of adjacent dissimilar conductive wires. This reduces the risk of short circuits and leakage in the stacking area, improving the reliability of the battery pack. Compared to the traditional fully flush design, this structure creates an independent, visible, and easily accessible test point on the exposed cantilever portion of the positive pole. Before packaging, probes can be used to directly contact the cantilever portion for testing and visual sorting, without disassembling the battery string or touching the internal grid lines of the stacking area. The testing operation is simple and compatible with automated mass production equipment. Furthermore, the structure where the metal conductive wires are recessed into the edge of the cell body prevents edge scratches, breakage, and delamination during battery handling, stacking, lamination, and packaging. It also reduces the erosion of the conductive wires by external moisture and impurities from the edges, improving the mechanical strength of the battery and the yield of the finished product.

[0027] The conductive connection structure 105 can combine the positive electrode conductive wires of the battery into an equipotential body, and the current can be evenly distributed among multiple conductive wires. This avoids uneven impedance of a single conductive wire and excessive local current, solves the series mismatch problem caused by uneven current distribution on the surface of large-size batteries, and improves the overall power generation efficiency of the module.

[0028] Example 2

[0029] like Figure 6 As shown, unlike Embodiment 1, no conductive connection structure 105 is provided. When two adjacent battery cells 10 are stacked and interconnected, the cantilever portion 104 of the first battery cell 10 is mounted on the negative current transmission structure 103 of the second battery cell 10. The connection is achieved through solder, conductive glue, conductive tape, etc. Although there is no conductive connection structure 105, the positive electrode is still exposed, which can achieve precise stacking and series connection and independent electrical performance testing, thus avoiding the problems of short circuit and poor soldering of positive and negative electrodes from the root.

[0030] In this case, as a better solution, a separate connecting line 107 can be added to ensure that the same electrodes of the solar cell are interconnected, thereby reducing the risk of mismatch caused by uneven current on the surface of the solar cell. Similarly, the connecting line needs to be provided with an insulating layer 106 at intervals to avoid short circuits.

[0031] Example 3

[0032] like Figure 7 As shown, unlike Embodiment 1, the battery pack uses the same type of batteries stacked and connected in series. In this case, all batteries of the first type 10A are stacked and interconnected. The conductive connection structure 105 is the same as in Embodiment 1. An insulating layer is provided at the non-conductive connection to avoid short circuits.

[0033] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A back-contact stacked-grid battery module, characterized in that, It includes at least two battery cells arranged along a first direction, each battery cell including a battery cell body and a positive current transmission structure and a negative current transmission structure disposed on the back of the battery cell body. Both the positive current transmission structure and the negative current transmission structure include a linear conductive element for collecting photogenerated charge carriers. In the battery cell, one end of the linear conductive element of the positive electrode current transmission structure extends to the edge of the battery cell body to form a cantilever, and the length of the extended cantilever is 0.5-5mm; the other end is flush with the edge of the battery cell body or recessed into the edge of the battery cell body by 0.5-5mm. Both ends of the linear conductive element of the negative electrode current transmission structure are flush with the edge of the battery cell body or recessed into the edge of the battery cell body by 0.5-5mm. The two adjacent battery cells are connected by a linear conductive element to form a stacked series battery assembly; the stacking width of the two adjacent battery cells is 0.1-2mm.

2. The back-contact stacked grid battery module according to claim 1, characterized in that, The battery cell includes a first type of battery and a second type of battery. The back of the first type of battery is arranged alternately in parallel with the positive current transmission structure and the negative current transmission structure in that order. The back of the second type of battery is arranged alternately in parallel with the negative current transmission structure and the positive current transmission structure in that order.

3. A back-contact stacked-grid battery module according to claim 2, characterized in that, The battery assembly is composed of alternating stacked and connected series of first-type and second-type batteries.

4. A back-contact stacked grid battery assembly according to claim 2, characterized in that, The battery assembly is composed of batteries of one type, namely a first type battery and a second type battery, stacked and connected in series.

5. A back-contact stacked-grid battery module according to claim 1, characterized in that, Each of the battery cells also includes a conductive connection structure, and all of the cantilever portions are connected to the conductive connection structure. Adjacent battery cells are connected through the conductive connection structure.

6. A back-contact stacked grid battery assembly according to claim 5, characterized in that, The linear conductive element is either a rigid conductive connector or a flexible conductive connector.

7. A back-contact stacked-grid battery module according to claim 6, characterized in that, The conductive connection structure is provided with a spaced insulating structure, which is located between two connected cantilever sections.

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