Back contact cell assembly and photovoltaic system

Abstract

The application is suitable for the technical field of solar cells, and provides a back contact cell assembly and a photovoltaic system. The back contact cell assembly comprises a first cell string and a second cell string; the first cell string comprises a first cell piece, a second cell piece and a series welding strip, and the second cell string comprises a third cell piece; a parallel welding strip; a plurality of electric connection structures of a first polarity electrically connecting the first cell piece and the third cell piece; a bus bar arranged on the first cell piece and electrically connected with the parallel welding strip; an insulating strip electrically isolating the bus bar and the series welding strip; the last electric connection structure of the parallel welding strip connected with the first cell piece is a first structure; a first section and a second section of the parallel welding strip are both electrically connected with the electric connection structure of the first polarity of the first cell piece and are respectively located on two sides of the bus bar, and the first section is located between the bus bar and the first structure; in the case that the back contact cell assembly is subjected to AM1.5 light, the current measured by the first section is greater than the current measured by the second section.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and more particularly to a back-contact battery module and photovoltaic system. Background Technology

[0002] Solar cell power generation is a sustainable and clean energy source that uses the photovoltaic effect of semiconductor pn junctions to convert sunlight into electrical energy.

[0003] In related technologies, several back-contact solar cells are typically connected using solder ribbons, and then the solder ribbons are connected using busbars to achieve electrical connection between the back-contact solar cells. However, the busbars are usually offset from the solar cells, making them easily visible from the front of the module, resulting in a poor visual appearance. Moreover, the busbars occupy the space inside the module where the solar cells are placed, leading to lower power generation efficiency of the module.

[0004] Therefore, improving the appearance and power generation efficiency of back-contact battery modules has become an urgent problem to be solved. Summary of the Invention

[0005] This application provides a back-contact battery module and a photovoltaic system, aiming to solve the technical problem of how to improve the appearance and power generation efficiency of back-contact battery modules in the prior art.

[0006] This application is implemented as follows: the back contact battery assembly of this application embodiment includes:

[0007] The first battery string and the second battery string each include a plurality of back contact battery cells connected in series, and the back contact battery cells include a plurality of electrical connection structures; the first battery string includes a first battery cell, a second battery cell and a series solder strip, the series solder strip electrically connects the electrical connection structure of the first polarity of the second battery cell to the electrical connection structure of the second polarity of the first battery cell; the second battery string includes a third battery cell, and the first battery cell is located between the second battery cell and the third battery cell;

[0008] Parallel welding strips, an electrical connection structure that electrically connects the first battery cell and the third battery cell to several first polarities;

[0009] A busbar is disposed on the first battery cell and electrically connected to the parallel welding strip;

[0010] An insulating strip is disposed between the busbar and the series solder strip to electrically isolate the busbar from the series solder strip;

[0011] Along the direction from the first battery cell to the third battery cell, the last electrical connection structure of the parallel solder strip connected to the first battery cell is the first structure;

[0012] The first and second segments of the parallel welding strip are both electrically connected to the electrical connection structure of the first polarity of the first battery cell, and are located on both sides of the busbar, with the first segment located between the busbar and the first structure.

[0013] When AM1.5 illumination is applied to the back contact battery assembly, W1 > W2;

[0014] Wherein, W1 is the current measured in the first segment, and W2 is the current measured in the second segment.

[0015] Specifically, along the direction from the first battery cell to the third battery cell, the first electrical connection structure where the parallel solder strip connects to the third battery cell is the second structure;

[0016] W1≤2W3;

[0017] Wherein, W3 is the current measured in the third segment of the parallel welding strip, and the third segment is located between the first structure and the second structure.

[0018] Specifically, along the direction from the first battery cell to the third battery cell, the first electrical connection structure where the parallel solder strip connects to the third battery cell is the second structure;

[0019] W2 < W3 < W1;

[0020] Wherein, W3 is the current measured in the third segment of the parallel welding strip, and the third segment is located between the first structure and the second structure.

[0021] Specifically, W1 > 2W2.

[0022] Specifically, R1 < R2;

[0023] Wherein, R1 is the resistance per unit length of the first segment, and R2 is the resistance per unit length of the second segment.

[0024] Specifically, the resistance per unit length of the first segment is less than the resistance per unit length of the series solder strips.

[0025] Specifically, the ratio of the resistance per unit length of the first segment to the resistance per unit length of the series solder strip is less than or equal to 3 / 4.

[0026] Specifically, the cross-sectional area of ​​the first segment is larger than the cross-sectional area of ​​the tandem welding strips.

[0027] Specifically, the cross-sections of the first segment and the tandem welding strips are rectangular, and the width of the cross-section of the first segment is greater than the width of the cross-section of the tandem welding strips.

[0028] Specifically, the cross-sections of the first segment and the tandem welding strips are rectangular, and the thickness of the cross-section of the first segment is greater than the thickness of the cross-section of the tandem welding strips.

[0029] Specifically, the cross-sections of the first segment and the tandem welding strips are rectangular, and the diameter of the cross-section of the first segment is larger than the diameter of the cross-section of the tandem welding strips.

[0030] Specifically, the resistivity per unit length of the first segment is less than the resistivity per unit length of the series-connected solder strips.

[0031] This application also provides a photovoltaic system, which includes the aforementioned back contact battery assembly.

[0032] In the back-contact battery module and photovoltaic system of this application embodiment, since the busbar is located on the first battery cell, the busbar is electrically isolated from the series solder strips by an insulating strip, and the busbar is electrically connected to the parallel solder strips, the busbar can be located on the back of the first battery cell. This makes the busbar difficult to observe from the front of the module, resulting in a better visual effect and freeing up more space to place the battery cells, thus increasing the module's power generation efficiency. Simultaneously, when AM1.5 illumination is applied to the module, the current measured in the first segment of the parallel solder strip closer to the second battery string is greater than the current measured in the second segment. Therefore, the solder strip segment with the larger current can be placed closer to the second battery string, connecting with and transmitting the large current generated by the second battery string to the busbar, resulting in better current collection by the busbar.

[0033] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a back contact battery assembly provided in one embodiment of this application;

[0035] Figure 2 This is a schematic diagram of the structure of a back contact battery assembly provided in one embodiment of this application;

[0036] Explanation of key component symbols:

[0037] Back contact battery assembly 100, first battery string 10, first battery cell 11, electrical connection structure 111, second battery cell 12, series welding strip 13, second battery string 20, third battery cell 21, insulating strip 30, busbar 40, parallel welding strip 50, first segment 51, second segment 58, third segment 59; first structure 101, second structure 109. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0039] In the description of this application, it should be understood that the terms "upper", "lower", "back", "front", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0040] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0041] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0042] Please see Figure 1 and Figure 2 The back contact battery assembly 100 of this application embodiment includes:

[0043] The first battery string 10 and the second battery string 20 both include a plurality of back contact battery cells connected in series. The back contact battery cells include a plurality of electrical connection structures 111. The first battery string 10 includes a first battery cell 11, a second battery cell 12 and a series solder strip 13. The series solder strip 13 electrically connects the first polarity electrical connection structure 111 of the second battery cell 12 and the second polarity electrical connection structure 111 of the first battery cell 11. The second battery string 20 includes a third battery cell 21. The first battery cell 11 is located between the second battery cell 12 and the third battery cell 21.

[0044] Parallel welding strip 50, several first polarity electrical connection structures 111 electrically connecting the first battery cell 11 and the third battery cell 21;

[0045] Busbar 40 is disposed on the first battery cell 11 and electrically connected to parallel welding strip 50;

[0046] An insulating strip 30 is disposed between the busbar 40 and the series solder strip 13 to electrically isolate the busbar 40 and the series solder strip 13.

[0047] Along the direction from the first battery cell 11 to the third battery cell 21, the last electrical connection structure 111 to which the parallel welding strip 50 is connected to the first battery cell 11 is the first structure 101;

[0048] The first segment 51 and the second segment 58 of the parallel welding strip 50 are both electrically connected to the first polarity electrical connection structure 111 of the first battery cell 11, and are located on both sides of the busbar 40 respectively. The first segment 51 is located between the busbar 40 and the first structure 101.

[0049] When AM1.5 illumination is applied to the back contact battery assembly 100, W1 > W2;

[0050] Wherein, W1 is the current measured in the first segment 51, and W2 is the current measured in the second segment 58.

[0051] In the back-contact battery module 100 of this application embodiment, since the busbar 40 is disposed on the first battery cell 11, the busbar 40 is electrically isolated from the series solder strip 13 by the insulating strip 30, and the busbar 40 is electrically connected to the parallel solder strip 50, the busbar 40 can be disposed on the back of the first battery cell 11. This makes the busbar 40 difficult to observe from the front of the module, resulting in a better visual effect and freeing up more space to place the battery cells, thus increasing the module's power generation efficiency. Simultaneously, since the current measured in the first segment 51 of the parallel solder strip 50 closer to the second battery string 20 is greater than the current measured in the second segment 58 when the module is illuminated with AM1.5 light, the solder strip segment with the larger current can be placed closer to the second battery string 20, connecting with and transmitting the large current generated by the second battery string 20 to the busbar 40, thus improving the current collection effect of the busbar 40.

[0052] Specifically, the back-contact battery assembly 100 includes a first series structure and a second series structure, which are connected in parallel and each includes a plurality of battery strings arranged along a first direction. Each battery string includes a plurality of back-contact battery cells arranged along a second direction, which intersects the first direction. The battery string of the first series structure is a first battery string 10. The battery string of the second series structure is a second battery string 20. The first battery string 10 and the second battery string 20 are arranged along the second direction.

[0053] Specifically, the first battery string 10 includes a plurality of back-contact battery cells connected in series. For example, the first battery string 10 includes 2, 3, 4, or other numbers of battery cells. Similarly, the second battery string 20 includes a plurality of back-contact battery cells connected in series. For example, the second battery string 20 includes 2, 3, 4, or other numbers of battery cells. The number of battery cells in the first battery string 10 and the second battery string 20 is not limited herein.

[0054] Specifically, the back contact solar cell may include a back contact solar cell with a main grid or a back contact solar cell without a main grid. The specific form of the back contact solar cell is not limited here.

[0055] Specifically, the back contact cell may include grid lines of a first polarity and grid lines of a second polarity, the first polarity being opposite to the second polarity. The back contact cell may include several electrical connection structures 111 disposed on the grid lines for electrically connecting solder strips. The electrical connection structure 111 includes at least one of solder pads, solder paste, conductive adhesive, and grid line segments. It is understood that the grid lines include grid lines of a first polarity and grid lines of a second polarity, and the electrical connection structures 111 disposed on the grid lines also include electrical connection structures of both first and second polarities.

[0056] Please note that the explanations and instructions regarding the back contact battery cells apply to the first battery cell 11, the second battery cell 12, and the third battery cell 21.

[0057] Specifically, the first battery string 10 includes a first battery cell 11 and a second battery cell 12, and the second battery string 20 includes a third battery cell 21. The first battery cell 11 is located between the second battery cell 12 and the third battery cell 21. That is to say, the second battery cell 12, the first battery cell 11, and the third battery cell 21 are arranged in sequence.

[0058] Specifically, the series solder strip 13 electrically connects the first polarity electrical connection structure of the second battery cell 12 to the second polarity electrical connection structure of the first battery cell 11. That is, the series solder strip 13 connects the first battery cell 11 and the second battery cell 12 in series.

[0059] exist Figure 1In the example, the number of tandem solder strips 13 is 7. It is understood that in other examples, the number of tandem solder strips 13 may be 1, 2, 3, 8 or other numbers, and is not limited here.

[0060] Specifically, a busbar 40 is disposed on the first solar cell 11 and electrically connected to the parallel solder strip 50. An insulating strip 30 is disposed between the busbar 40 and the series solder strip 13, electrically isolating the busbar 40 from the series solder strip 13. Further, the insulating strip 30 is disposed on the side of the series solder strip 13 connected to the first solar cell 11 that faces away from the first solar cell 11, and the busbar 40 is disposed on the side of the insulating strip 30 that faces away from the first solar cell 11. In other words, the insulating strip 30 and the busbar 40 are sequentially stacked on the side of the series solder strip 13 connected to the first solar cell 11 that faces away from the first solar cell 11. The insulating strip 30 is located between the busbar 40 and the series solder strip 13 connected to the first solar cell 11.

[0061] Specifically, the insulating strip 30 may have a through-hole, through which the busbar 40 is electrically connected to the parallel solder strip 50. A conductive element may be provided within the through-hole, electrically connecting the busbar 40 and the parallel solder strip 50. The conductive element includes at least one of solder paste, conductive adhesive, and a metal block. Alternatively, no conductive element may be provided within the through-hole. For example, the busbar 40 may protrude from the through-hole, pass through the through-hole, and be electrically connected to the parallel solder strip 50. Another example is that the parallel solder strip 50 may protrude from the through-hole, pass through the through-hole, and be electrically connected to the busbar 40. Yet another example is that both the busbar 40 and the parallel solder strip 50 may protrude from the through-hole and be electrically connected within the through-hole.

[0062] Specifically, the insulating strip 30 includes at least one of POE, EVA, and EPE.

[0063] Specifically, at least a portion of the busbar 40 is located on the first battery cell 11. Further, the entire busbar 40 may be located on the first battery cell 11. Alternatively, a portion of the busbar 40 may be located on the first battery cell 11, with other portions located between the first battery cell 11 and the second battery cell 12. Or, a portion of the busbar 40 may be located on the first battery cell 11, another portion between the first battery cell 11 and the second battery cell 12, with the remainder located on the second battery cell 12. The insulating strip 30 may be entirely located on the first battery cell 11. Alternatively, a portion of the insulating strip 30 may be located on the first battery cell 11, with other portions located between the first battery cell 11 and the second battery cell 12. Or, a portion of the insulating strip 30 may be located on the first battery cell 11, another portion between the first battery cell 11 and the second battery cell 12, with the remainder located on the second battery cell 12.

[0064] Specifically, the insulating strip 30 is located between the busbar 40 and the series solder strip 13. The insulating strip 30 may be entirely located between the busbar 40 and the series solder strip 13. Alternatively, a portion of the insulating strip 30 may be located between the busbar 40 and the series solder strip 13, with the remainder located outside of these two sections.

[0065] Specifically, along the direction from the first battery cell 11 to the third battery cell 21, the last electrical connection structure 111 to which the parallel welding strip 50 connects to the first battery cell 11 is the first structure 101. It can be understood that the direction from the first battery cell 11 to the third battery cell 21, that is... Figure 1 The direction from top to bottom in the middle, Figure 2 The direction from left to right in the middle.

[0066] Specifically, the first segment 51 and the second segment 58 of the parallel welding strip 50 are both electrically connected to the first polarity electrical connection structure 111 of the first battery cell 11, and are located on both sides of the busbar 40, with the first segment 51 located between the busbar 40 and the first structure 101.

[0067] In other words, the parallel welding strip 50 electrically connects the first polarity of the first battery cell 11 and the first polarity of the third battery cell 21. The parallel welding strip 50 includes a first segment 51 and a second segment 58, both of which are electrically connected to the first polarity of the first battery cell 11, and are located on the side of the busbar 40 facing the third battery cell 21 and the side away from the third battery cell 21, respectively.

[0068] In other words, along the direction from the first battery cell 11 to the third battery cell 21, the second segment 58, the busbar 40, the first segment 51, and the first structure 101 are arranged sequentially.

[0069] exist Figure 1 In the example, the number of parallel solder strips 50 is 7. It is understood that in other examples, the number of parallel solder strips 50 may be 1, 2, 3, 8 or other numbers, and is not limited here.

[0070] Specifically, in the back contact battery assembly 100 test, under standard test conditions, L1 > L2. The standard test conditions are AM1.5 and 1000W / m. 2 The test was conducted at 25℃.

[0071] Please see Figure 1 and Figure 2 In some embodiments, the first electrical connection structure 111 where the parallel welding strip 50 is connected to the third battery cell 21 along the direction from the first battery cell 11 to the third battery cell 21 is the second structure 109.

[0072] W1≤2W3;

[0073] W3 is the current measured in the third segment 59 of the parallel welding strip 50, which is located between the first structure 101 and the second structure 109.

[0074] This ensures that the current measured in the first segment 51 of the parallel welding strip 50 is less than or equal to twice the current measured in the third segment 59, allowing for a current margin to account for heat loss. Furthermore, it allows for flexibility in the photovoltaic system's power generation dispatch strategy, making the power generation dispatch of the photovoltaic system more rational.

[0075] Specifically, W1 can be, for example, 2W3, 1.9W3, 1.8W3, 1.7W3, 1.5W3, 1.2W3, W3, 0.8W3, 0.6W3, 0.5W3, 0.3W3, 0.2W3, or 0.1W3. No specific limit is imposed here.

[0076] Specifically, the parallel welding strip 50 connects several electrical connection structures 111 of the first polarity of the first battery cell 11 and several electrical connection structures 111 of the first polarity of the third battery cell 21. The electrical connection structures 111 connected by the parallel welding strip 50 are arranged along the extension direction of the parallel welding strip 50. Along the direction from the first battery cell 11 to the third battery cell 21, one end of the third segment 59 is electrically connected to the last electrical connection structure 111 of the first battery cell 11, i.e., the first structure 101, and the other end of the third segment 59 is electrically connected to the first electrical connection structure 111 of the third battery cell 21, i.e., the second structure 109.

[0077] In other words, along the direction from the first battery cell 11 to the third battery cell 21, the third segment 59 is located between the last electrical connection structure 111 of the first battery cell 11 and the first electrical connection structure 111 of the third battery cell 21.

[0078] Please see Figure 1 and Figure 2 In some embodiments, the first electrical connection structure 111 where the parallel welding strip 50 is connected to the third battery cell 21 along the direction from the first battery cell 11 to the third battery cell 21 is the second structure 109.

[0079] W2 < W3 < W1;

[0080] W3 is the current measured in the third segment 59 of the parallel welding strip 50, which is located between the first structure 101 and the second structure 109.

[0081] In this way, the current measured in the third segment 59 of the parallel welding strip 50 is less than the current measured in the first segment 51 and greater than the current measured in the second segment 58, so that the current carried by the third segment 59 is within a suitable range. This can avoid the insufficient power generation efficiency of the second battery string 20 due to the current carried by the third segment 59 being too small, and can also avoid the excessive heat generation and current loss due to the current carried by the third segment 59 being too large.

[0082] Please see Figure 1 and Figure 2 In some embodiments, W1 > 2W2.

[0083] Thus, the current measured in the first segment 51 is more than twice the current measured in the second segment 58, resulting in a larger current carried by the first segment 51 and a higher power generation efficiency of the module.

[0084] Specifically, W1 can be, for example, 2.1W2, 2.5W2, 3W2, 5W2, 8W2, 10W2, 20W2, 50W2, 80W2, etc. No specific limit is imposed here.

[0085] Please see Figure 1 and Figure 2 In some embodiments, R1 < R2; where R1 is the resistance per unit length of the first segment 51 and R2 is the resistance per unit length of the second segment 58.

[0086] Thus, the resistance per unit length of the first segment 51 is less than that of the second segment 58, resulting in a smaller resistance per unit length of the first segment 51 with a larger current. This reduces the larger heat loss caused by the larger current, which is beneficial to improving the power generation efficiency of the back contact battery module 100.

[0087] Specifically, R1 can be, for example, 0.9R2, 0.8R2, 0.6R2, 0.5R2, 0.3R2, 0.2R2, or 0.1R2. No specific limit is imposed here.

[0088] Please see Figure 1 and Figure 2 In some embodiments, the resistance per unit length of the first segment 51 is less than the resistance per unit length of the series solder strip 13.

[0089] This results in a smaller resistance per unit length for the first segment 51 with a larger current, thereby reducing the significant heat loss caused by the larger current and improving the power generation efficiency of the back contact battery module 100.

[0090] Please see Figure 1 and Figure 2In some embodiments, the ratio of the resistance per unit length of the first segment 51 to the resistance per unit length of the series solder strip 13 is less than or equal to 3 / 4. For example, it is 0.75, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, or 0.05.

[0091] This ensures that the ratio of the resistance per unit length of the first segment 51 to the series welding strip 13 is within a suitable range, avoiding a poor effect in reducing heat loss due to an excessively large ratio, and thus improving the power generation efficiency of the back contact battery module 100.

[0092] Please see Figure 1 and Figure 2 In some embodiments, the ratio of the resistance per unit length of the first segment 51 to the resistance per unit length of the series solder strip 13 is less than or equal to 1 / 2. For example, it is 0.5, 0.49, 0.45, 0.4, 0.3, 0.2, 0.1, or 0.05.

[0093] In this way, the ratio of the resistance per unit length of the first segment 51 to the resistance per unit length of the series solder strip 13 is further optimized, thereby further reducing the heat loss caused by high current.

[0094] Please see Figure 1 and Figure 2 In some embodiments, the ratio of the resistance per unit length of the first segment 51 to the resistance per unit length of the series solder strip 13 is less than or equal to 1 / 4. For example, it is 0.25, 0.24, 0.22, 0.2, 0.19, 0.17, 0.15, 0.14, 0.12, 0.1, 0.05, or 0.02.

[0095] This further optimizes the ratio of the resistance per unit length of the first segment 51 to the resistance per unit length of the series solder strip 13, and further reduces the heat loss caused by high current.

[0096] Please note that the ratio of the resistance per unit length of the first segment 51 to the resistance per unit length of the series solder strip 13 can be a fixed value within the aforementioned range, or it can fluctuate within the aforementioned range; no limitation is made here.

[0097] Please see Figure 1 and Figure 2 In some embodiments, the cross-sectional area of ​​the first segment 51 is larger than the cross-sectional area of ​​the tandem solder strip 13.

[0098] In this way, by adjusting the cross-sectional area of ​​the first segment 51 to be larger than that of the series welding strip 13, the resistance per unit length of the first segment 51 is less than that per unit length of the series welding strip 13, thereby reducing the heat loss of the first segment 51 carrying a large current.

[0099] Specifically, the ratio of the cross-sectional area of ​​the series solder strip 13 to the cross-sectional area of ​​the first segment 51 is less than or equal to 3 / 4. For example, it is 0.75, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, or 0.05. This ensures that the ratio of the cross-sectional area of ​​the series solder strip 13 to the cross-sectional area of ​​the first segment 51 is within a suitable range, thus ensuring that the ratio of the resistance per unit length of the first segment 51 to the series solder strip 13 is within a suitable range. This avoids a ratio that is too large, which would result in a poor effect on reducing heat loss and is beneficial for improving the power generation efficiency of the back contact battery module 100.

[0100] Please note that the ratio of the cross-sectional area of ​​the first segment 51 to the cross-sectional area of ​​the second segment 58 can be a fixed value within the aforementioned range, or it can fluctuate within the aforementioned range; no limitation is imposed here.

[0101] Specifically, the cross-sectional area of ​​the first segment 51 is 0.027 mm². 2 -0.3mm 2 For example, 0.027mm. 2 0.029mm 2 0.03mm 2 0.05mm 2 0.1mm 2 0.15mm 2 0.2mm 2 0.25mm 2 0.27mm 2 0.3mm 2 .

[0102] Specifically, the cross-sectional area of ​​the tandem welding strip 13 is 0.02 mm. 2 -0.2mm 2 For example, 0.02mm 2 0.022mm 2 0.03mm 2 0.08mm 2 0.1mm 2 0.15mm 2 0.18mm 2 0.2mm 2 .

[0103] Please see Figure 1 and Figure 2 In some embodiments, the cross-sections of the first segment 51 and the tandem solder strip 13 are rectangular, and the width of the cross-section of the first segment 51 is greater than the width of the cross-section of the tandem solder strip 13.

[0104] Thus, by adjusting the width of the cross-section of the first segment 51, which has a rectangular cross-section, to be larger than that of the series welding strip 13, the cross-sectional area of ​​the first segment 51 is larger than that of the series welding strip 13. This makes the resistance per unit length of the first segment 51 smaller than that per unit length of the series welding strip 13, thereby reducing the heat loss of the first segment 51 that carries a large current.

[0105] Specifically, the ratio of the width of the cross-section of the series solder strip 13 to the width of the cross-section of the first segment 51 is less than or equal to 3 / 4. For example, it is 0.75, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, or 0.05. This ensures that the ratio of the width of the cross-section of the series solder strip 13 to the width of the cross-section of the first segment 51 is within a suitable range, thus ensuring that the ratio of the resistance per unit length of the first segment 51 to that of the series solder strip 13 is within a suitable range. This avoids a ratio that is too large, which would result in a poor effect on reducing heat loss and is beneficial for improving the power generation efficiency of the back contact battery module 100.

[0106] Please note that the ratio of the width of the first segment 51 to the width of the second segment 58 can be a fixed value within the aforementioned range, or it can fluctuate within the aforementioned range; no limitation is imposed here.

[0107] Specifically, the width of the cross-section of the first segment 51 is greater than or equal to 0.8 mm. For example, it can be 0.8 mm, 0.9 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 5 mm, 8 mm, or 10 mm. This ensures the width of the cross-section of the first segment 51 is within a suitable range, avoiding excessive resistance and heat loss caused by an excessively small width. Preferably, the width of the cross-section of the first segment 51 is between 0.8 mm and 2 mm.

[0108] Specifically, the width of the cross-section of the tandem solder strip 13 is 0.6mm to 1.5mm. For example, it can be 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, or 1.5mm. This ensures that the width of the cross-section of the tandem solder strip 13 is within a suitable range, avoiding excessive resistance, excessive heat loss, and difficulty in soldering due to an excessively small width, and also avoiding high costs due to an excessively large width.

[0109] Please see Figure 1 and Figure 2 In some embodiments, the cross-sections of the first segment 51 and the tandem solder strip 13 are rectangular, and the thickness of the cross-section of the first segment 51 is greater than the thickness of the cross-section of the tandem solder strip 13.

[0110] Thus, by adjusting the thickness of the cross-section of the first segment 51, which has a rectangular cross-section, to be larger than that of the series welding strip 13, the cross-sectional area of ​​the first segment 51 is larger than that of the series welding strip 13. This makes the resistance per unit length of the first segment 51 less than that per unit length of the series welding strip 13, thereby reducing the heat loss of the first segment 51 that carries a large current.

[0111] Specifically, the ratio of the thickness of the cross-section of the series solder strip 13 to the thickness of the cross-section of the first segment 51 is less than or equal to 3 / 4. For example, it is 0.75, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, or 0.05. This ensures that the ratio of the thickness of the cross-section of the series solder strip 13 to the thickness of the cross-section of the first segment 51 is within a suitable range, thus ensuring that the ratio of the resistance per unit length of the first segment 51 to the series solder strip 13 is within a suitable range. This avoids a ratio that is too large, which would result in a poor effect on reducing heat loss and is beneficial for improving the power generation efficiency of the back contact battery module 100.

[0112] Please note that the ratio of the thickness of the first segment 51 to the thickness of the second segment 58 can be a fixed value within the aforementioned range, or it can fluctuate within the aforementioned range, and is not limited here.

[0113] Specifically, the thickness of the cross-section of the first segment 51 is greater than or equal to 0.11 mm. For example, it can be 0.11 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.25 mm, 0.267 mm, 0.3 mm, 0.5 mm, or 1 mm. This ensures the thickness of the cross-section of the first segment 51 is within a suitable range, avoiding excessive resistance and heat loss caused by an excessively small thickness. Preferably, the thickness of the cross-section of the first segment 51 is between 0.11 mm and 0.267 mm.

[0114] Specifically, the thickness of the cross-section of the tandem solder strip 13 is 0.08mm to 0.20mm. For example, it is 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.13mm, 0.15mm, 0.18mm, 0.19mm, or 0.2mm. This ensures that the thickness of the cross-section of the tandem solder strip 13 is within a suitable range, avoiding excessive resistance, excessive heat loss, and difficulty in soldering caused by excessive thickness, and also avoiding high costs caused by excessive thickness.

[0115] Please see Figure 1 and Figure 2 In some embodiments, the cross-sections of the first segment 51 and the tandem welding strip 13 are circular, and the diameter of the cross-section of the first segment 51 is larger than the diameter of the cross-section of the tandem welding strip 13.

[0116] Thus, by adjusting the diameter of the first segment 51, which has a circular cross-section, to be larger than that of the series welding strip 13, the cross-sectional area of ​​the first segment 51 is larger than that of the series welding strip 13, thereby making the resistance per unit length of the first segment 51 less than that per unit length of the series welding strip 13, thereby reducing the heat loss of the first segment 51 that carries a large current.

[0117] Specifically, the ratio of the diameter of the cross-section of the series welding strip 13 to the diameter of the cross-section of the first segment 51 is less than or equal to 3 / 4. For example, it is 0.75, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, or 0.05. This ensures that the ratio of the diameter of the cross-section of the series welding strip 13 to the diameter of the cross-section of the first segment 51 is within a suitable range, thus ensuring that the ratio of the resistance per unit length of the first segment 51 to that of the series welding strip 13 is within a suitable range. This avoids a ratio that is too large, which would result in a poor reduction in heat loss and is beneficial for improving the power generation efficiency of the back contact battery module 100.

[0118] Please note that the ratio of the diameter of the cross section of the first segment 51 to the diameter of the cross section of the second segment 58 can be a fixed value within the aforementioned range, or it can fluctuate within the aforementioned range, and is not limited here.

[0119] Specifically, the diameter of the cross-section of the first segment 51 is greater than or equal to 0.16 mm. For example, it can be 0.16 mm, 0.17 mm, 0.18 mm, 0.2 mm, 0.25 mm, 0.267 mm, 0.3 mm, 0.347 mm, 0.5 mm, or 1 mm. This ensures the diameter of the cross-section of the first segment 51 is within a suitable range, avoiding excessive resistance and heat loss caused by an excessively small diameter. Preferably, the diameter of the cross-section of the first segment 51 is between 0.16 mm and 0.347 mm.

[0120] Specifically, the diameter of the cross-section of the tandem solder strip 13 is 0.12mm to 0.26mm. For example, it is 0.12mm, 0.13mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.23mm, 0.24mm, 0.25mm, or 0.26mm. This ensures that the diameter of the cross-section of the tandem solder strip 13 is within a suitable range, avoiding excessive resistance, excessive heat loss, and difficulty in soldering caused by an excessively small diameter, and also avoiding the high cost caused by an excessively large diameter.

[0121] Please see Figure 1 and Figure 2 In some embodiments, the resistivity per unit length of the first segment 51 is less than the resistivity per unit length of the series solder strip 13.

[0122] Thus, by adjusting the resistivity of the first segment 51 in the parallel welding strip 50 to be smaller than that of the series welding strip 13, the resistance per unit length of the first segment 51 is less than that per unit length of the series welding strip 13, thereby reducing the heat loss of the first segment 51 carrying a large current.

[0123] Specifically, the ratio of the resistivity per unit length of the first segment 51 to the resistivity per unit length of the series solder strip 13 is less than or equal to 3 / 4. For example, ratios such as 0.75, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, and 0.05 are used. This ensures that the ratio of the resistivity per unit length of the first segment 51 to the resistivity per unit length of the series solder strip 13 is within a suitable range. This avoids a ratio that is too large, which would result in a poor reduction in heat loss and is beneficial for improving the power generation efficiency of the back contact battery module 100.

[0124] Please note that the ratio of the resistivity per unit length of the first segment 51 to the resistivity per unit length of the series solder strip 13 can be a fixed value within the aforementioned range, or it can fluctuate within the aforementioned range, and is not limited here.

[0125] Specifically, the resistivity per unit length of the first segment 51 is 1.6 × 10⁻⁶. -8 Ω·m-2.82×10 -8 Ω·m.

[0126] Specifically, the resistivity per unit length of the series solder strip 13 is 1.68 × 10⁻⁶. -8 Ω·m-2.82×10 -8 Ω·m.

[0127] Specifically, the first paragraph 51 includes at least one of copper solder strip and copper-aluminum solder strip.

[0128] Specifically, the tandem solder strip 13 includes at least one of copper solder strip and copper-aluminum solder strip.

[0129] In some examples, the cross-sectional area of ​​the first segment 51 gradually increases along the direction from the third cell 21 to the first cell 11. This allows the gradual change in the cross-sectional area of ​​the first segment 51 to adapt to the gradual change in current, reducing heat loss and material costs.

[0130] In addition, the battery module may also include a metal frame, a backsheet, photovoltaic glass, and an encapsulating film. The encapsulating film can be filled between the front and back of the back-contact cells, as well as between the photovoltaic glass and adjacent cells. As a filler, it can be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulating film can be EVA film or POE film. The specific choice can be made according to the actual situation and is not limited here.

[0131] Photovoltaic glass can be applied to the encapsulating film on the front side of the back contact solar cell. This photovoltaic glass can be ultra-clear glass, possessing high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, ultra-clear glass can achieve a light transmittance of over 92%, protecting the back contact solar cell while minimizing impact on its efficiency. Simultaneously, the encapsulating film bonds the photovoltaic glass and the back contact solar cell together, providing sealing, insulation, and waterproofing / moisture protection for the back contact solar cell.

[0132] The backsheet can be attached to the adhesive film on the back of the back contact solar cells. The backsheet protects and supports the cells, providing reliable insulation, water resistance, and aging resistance. Multiple backsheet options are available, typically including tempered glass, acrylic glass, aluminum alloy TPT composite adhesive film, etc., with specific choices depending on the specific circumstances. The backsheet, back contact solar cells, adhesive film, and photovoltaic glass can be mounted on a metal frame. The metal frame serves as the main external support structure for the entire solar module, providing stable support and installation. For example, the solar module can be installed at the desired location using the metal frame.

[0133] The photovoltaic system of this application embodiment includes the back contact battery module 100 of any of the above.

[0134] In the photovoltaic system of this application embodiment, since the busbar 40 is disposed on the first cell 11 in the back-contact battery module 100, the busbar 40 is electrically isolated from the series solder strip 13 by the insulating strip 30, and the busbar 40 is electrically connected to the parallel solder strip 50, the busbar 40 can be disposed on the back of the first cell 11. This makes the busbar 40 difficult to observe from the front of the module, resulting in a better visual effect and freeing up more space to place the cells, thus increasing the power generation efficiency of the module. At the same time, since the current measured in the first segment 51 of the parallel solder strip 50, which is closer to the second cell string 20, is greater than the current measured in the second segment 58, the solder strip segment with the larger current can be placed closer to the second cell string 20, connecting with and transmitting the large current generated by the second cell string 20 to the busbar 40, thus improving the current collection effect of the busbar 40.

[0135] In this embodiment, the photovoltaic system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system are not limited to these; that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0136] In the description of this specification, the references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0137] Furthermore, the above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A back-contact battery assembly, characterized in that, include: The first battery string and the second battery string each include a plurality of back contact battery cells connected in series, and the back contact battery cells include a plurality of electrical connection structures; the first battery string includes a first battery cell, a second battery cell and a series solder strip, the series solder strip electrically connects the electrical connection structure of the first polarity of the second battery cell to the electrical connection structure of the second polarity of the first battery cell; the second battery string includes a third battery cell, and the first battery cell is located between the second battery cell and the third battery cell; Parallel welding strips, an electrical connection structure that electrically connects the first battery cell and the third battery cell to several first polarities; A busbar is disposed on the first battery cell and electrically connected to the parallel welding strip; An insulating strip is disposed between the busbar and the series solder strip to electrically isolate the busbar from the series solder strip; Along the direction from the first battery cell to the third battery cell, the last electrical connection structure of the parallel solder strip connected to the first battery cell is the first structure; The first and second segments of the parallel welding strip are both electrically connected to the electrical connection structure of the first polarity of the first battery cell, and are located on both sides of the busbar, with the first segment located between the busbar and the first structure. When AM1.5 illumination is applied to the back contact battery assembly, W1 > W2; Wherein, W1 is the current measured in the first segment, and W2 is the current measured in the second segment.

2. The back contact battery assembly according to claim 1, characterized in that, Along the direction from the first battery cell to the third battery cell, the first electrical connection structure where the parallel solder strip connects to the third battery cell is a second structure; W1≤2W3; Wherein, W3 is the current measured in the third segment of the parallel welding strip, and the third segment is located between the first structure and the second structure.

3. The back contact battery assembly according to claim 1, characterized in that, Along the direction from the first battery cell to the third battery cell, the first electrical connection structure where the parallel solder strip connects to the third battery cell is a second structure; W2 < W3 < W1; Wherein, W3 is the current measured in the third segment of the parallel welding strip, and the third segment is located between the first structure and the second structure.

4. The back contact battery assembly according to claim 1, characterized in that, W1 > 2W2.

5. The back contact battery assembly according to claim 1, characterized in that, R1 < R2; Wherein, R1 is the resistance per unit length of the first segment, and R2 is the resistance per unit length of the second segment.

6. The back contact battery assembly according to claim 1, characterized in that, The resistance per unit length of the first segment is less than the resistance per unit length of the series solder strips.

7. The back contact battery assembly according to claim 6, characterized in that, The ratio of the resistance per unit length of the first segment to the resistance per unit length of the series solder strip is less than or equal to 3 / 4.

8. The back contact battery assembly according to claim 6, characterized in that, The cross-sectional area of ​​the first segment is larger than the cross-sectional area of ​​the tandem welding strips.

9. The back contact battery assembly according to claim 6, characterized in that, The first segment and the tandem welding strip have rectangular cross-sections, and the width of the first segment's cross-section is greater than the width of the tandem welding strip's cross-section.

10. The back contact battery assembly according to claim 6, characterized in that, The first segment and the tandem welding strip have rectangular cross-sections, and the thickness of the first segment's cross-section is greater than the thickness of the tandem welding strip's cross-section.

11. The back contact battery assembly according to claim 6, characterized in that, The first segment and the tandem welding strips have circular cross-sections, and the diameter of the first segment's cross-section is larger than the diameter of the tandem welding strips' cross-section.

12. The back contact battery assembly according to claim 6, characterized in that, The resistivity per unit length of the first segment is less than the resistivity per unit length of the series-connected solder strips.

13. A photovoltaic system, characterized in that, Includes the back contact battery assembly as described in any one of claims 1-12.

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