Back contact battery assembly and photovoltaic system

Abstract

The invention is suitable for the technical field of solar cells, and provides a back contact cell module and a photovoltaic system. The back contact battery assembly comprises a first battery string and a second battery string; the first battery string comprises a first battery piece, a second battery piece and a series welding strip, and the second battery string comprises a third battery piece; the parallel welding strip is electrically connected with a plurality of first-polarity electric connection structures of the first battery piece and the third battery piece; the bus bar is arranged on the first battery piece and is electrically connected with the parallel welding strip; the insulating strip is used for electrically isolating the bus bar from the series welding strip; the last electric connection structure of the parallel welding strip connected with the first battery piece is a first structure; the first section and the second section of the parallel welding strip are electrically connected with the electric connection structure of the first polarity of the first battery piece and located on the two sides of the bus bar respectively, and the first section is located between the bus bar and the first structure; under the condition that AM 1.5 illumination is applied to the back contact battery assembly, the current measured by the first section is larger than the current measured by the second section.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a back-contact cell assembly and a photovoltaic system. Background Art

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

[0003] In the prior art, solder ribbons are typically used to connect several back-contact solar cells, and busbars are then used to connect the ribbons to achieve electrical connection between the back-contact solar cells. However, the busbars are often offset from the solar cells, making them easily visible from the front of the module, resulting in a poor visual effect. Furthermore, the busbars occupy the space within the module where the solar cells are placed, resulting in lower power generation efficiency.

[0004] Based on this, how to improve the appearance and power generation efficiency of back-contact battery modules has become an urgent problem to be solved. Summary of the Invention

[0005] The present application provides a back-contact cell assembly and a photovoltaic system, aiming to solve the technical problem of how to improve the appearance and power generation efficiency of the back-contact cell assembly in the prior art.

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

[0007] A first battery string and a second battery string each include a plurality of back-contact battery cells connected in series, wherein 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 welding ribbon, wherein the series welding ribbon 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 electrically connecting the first battery cell and the plurality of first polarity electrical connection structures of the third battery cell;

[0009] a bus bar, provided on the first battery cell and electrically connected to the parallel welding ribbon;

[0010] an insulating strip, provided between the bus bar and the series welding strip, electrically isolating the bus bar from the series welding strip;

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

[0012] The first and second sections of the parallel welding ribbon are both electrically connected to the electrical connection structure of the first polarity of the first battery cell and are respectively located on both sides of the bus bar, with the first section being located between the bus bar and the first structure;

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

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

[0015] Specifically, along the direction from the first battery cell to the third battery cell, the first electrical connection structure connected by the parallel welding ribbon at the third battery cell is the second structure;

[0016] W1≤2W3;

[0017] Wherein, W3 is the current measured at the third section of the parallel welding strip, and the third section 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 connected by the parallel welding ribbon at the third battery cell is the second structure;

[0019] W2<W3<W1;

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

[0021] Specifically, W1>2W2.

[0022] Specifically, R1<R2;

[0023] Here, 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 smaller than the resistance per unit length of the series welding ribbon.

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

[0026] Specifically, the cross-sectional area of the first section is larger than the cross-sectional area of the series welding ribbon.

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

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

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

[0030] Specifically, the resistivity per unit length of the first segment is smaller than the resistivity per unit length of the series welding ribbon.

[0031] The present application also provides a photovoltaic system, which includes the above-mentioned back-contact cell assembly.

[0032] In the back-contact cell assembly and photovoltaic system of the embodiments of the present application, since the busbar is provided on the first cell, the busbar electrically isolates the series welding ribbons via an insulating strip, and the busbar electrically connects the parallel welding ribbons, the busbar can be provided on the back of the first cell, making the busbar difficult to observe from the front of the assembly, resulting in a better visual effect, and freeing up more space for the cells, thereby increasing the power generation efficiency of the assembly. At the same time, since the current measured in the first section of the parallel welding ribbon closer to the second cell string is greater than the current measured in the second section when AM1.5 light is applied to the assembly, the welding ribbon section with higher current can be placed closer to the second cell string, connecting with the large amount of current generated by the second cell string and transmitting it to the busbar, thereby improving the busbar's current collection effect.

[0033] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 1 is a schematic structural diagram of a back-contact battery assembly provided in one embodiment of the present application;

[0035] Figure 2 1 is a schematic structural diagram of a back-contact battery assembly provided in one embodiment of the present application;

[0036] Description of main 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 ribbon 13, second battery string 20, third battery cell 21, insulating strip 30, bus bar 40, parallel welding ribbon 50, first section 51, second section 58, third section 59; first structure 101, second structure 109. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are merely used to explain the present application and are not intended to limit the present application.

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

[0040] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0041] The disclosure below provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those skilled in the art will appreciate the application of other processes and / or the use scenarios of other materials.

[0042] See also Figure 1 and Figure 2 The back contact battery assembly 100 of the embodiment of the present application includes:

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

[0044] The parallel welding ribbon 50 electrically connects the first battery cell 11 and the third battery cell 21 to form a plurality of first polarity electrical connection structures 111;

[0045] The bus bar 40 is provided on the first cell 11 and electrically connected to the parallel welding ribbon 50;

[0046] The insulating strip 30 is provided between the bus bar 40 and the series welding strip 13 to electrically isolate the bus bar 40 from the series welding strip 13;

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

[0048] The first section 51 and the second section 58 of the parallel welding ribbon 50 are both electrically connected to the first polarity electrical connection structure 111 of the first battery cell 11 and are respectively located on both sides of the bus bar 40 , with the first section 51 being located between the bus bar 40 and the first structure 101 ;

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

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

[0051] In the back-contact battery module 100 of the present embodiment, since the busbar 40 is disposed on the first battery cell 11, the busbar 40 electrically isolates the series welding ribbon 13 via the insulating strip 30, and the busbar 40 electrically connects the parallel welding ribbon 50, the busbar 40 can be disposed on the back of the first battery cell 11, making the busbar 40 difficult to observe from the front of the module, resulting in a better visual effect. Furthermore, more space can be freed up for the battery cells, thereby increasing the module's power generation efficiency. Furthermore, since the current measured in the first section 51 of the parallel welding ribbon 50, which is closer to the second battery string 20, is greater than the current measured in the second section 58 when AM1.5 light is applied to the module, the section of the welding ribbon with higher current can be placed closer to the second battery string 20, connecting with the large amount of current generated by the second battery string 20 and transmitting it to the busbar 40, thereby improving the busbar 40's current collection effect.

[0052] Specifically, back-contact battery assembly 100 includes a first series structure and a second series structure, which are connected in parallel and each include a plurality of battery strings arranged along a first direction. The battery strings include a plurality of back-contact battery cells arranged along a second direction, which intersects the first direction. The battery string in the first series structure is a first battery string 10. The battery string in 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 two, three, four, or another number 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 two, three, four, or another number 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 cell may include a busbar back contact cell or a busbar-free back contact cell, and the specific form of the back contact cell is not limited herein.

[0055] Specifically, the back-contact cell may include grid lines of a first polarity and grid lines of a second polarity, where the first polarity is opposite to the second polarity. The back-contact cell may include a plurality of electrical connection structures 111, which are provided on the grid lines for electrically connecting to the soldering ribbons. The electrical connection structures 111 include 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 provided on the grid lines also include electrical connection structures 111 of a first polarity and electrical connection structures 111 of a second polarity.

[0056] Please note that the explanations and descriptions regarding the back-contact cell are applicable to the first cell 11 , the second cell 12 and the third 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. In other words, the second battery cell 12, the first battery cell 11, and the third battery cell 21 are arranged in sequence.

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

[0059] exist Figure 1In the example of , the number of the series welding ribbons 13 is 7. It can be understood that in other examples, the number of the series welding ribbons 13 can be 1, 2, 3, 8 or other numbers, which are not limited here.

[0060] Specifically, the bus bar 40 is provided on the first cell 11 and electrically connected to the parallel welding ribbon 50. The insulating bar 30 is provided between the bus bar 40 and the series welding ribbon 13, electrically isolating the bus bar 40 from the series welding ribbon 13. Furthermore, the insulating bar 30 is provided on the side of the series welding ribbon 13 connected to the first cell 11 that faces away from the first cell 11, and the bus bar 40 is provided on the side of the insulating bar 30 that faces away from the first cell 11. In other words, the insulating bar 30 and the bus bar 40 are stacked sequentially on the side of the series welding ribbon 13 connected to the first cell 11 that faces away from the first cell 11. The insulating bar 30 is located between the bus bar 40 and the series welding ribbon 13 connected to the first cell 11.

[0061] Specifically, the insulating strip 30 may be formed with a through-hole, through which the busbar 40 is electrically connected to the parallel solder ribbon 50. A conductive member may be provided in the through-hole, electrically connecting the busbar 40 and the parallel solder ribbon 50. The conductive member includes at least one of solder paste, conductive glue, and a metal block. The through-hole may also be free of a conductive member. For example, the busbar 40 may protrude from the through-hole, pass through the through-hole, and electrically connect to the parallel solder ribbon 50. In another example, the parallel solder ribbon 50 may protrude from the through-hole, pass through the through-hole, and electrically connect to the busbar 40. In another example, both the busbar 40 and the parallel solder ribbon 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 part of the structure of the bus bar 40 is provided on the first battery cell 11. Furthermore, the entire structure of the bus bar 40 may be located on the first battery cell 11. The bus bar 40 may have a part of its structure located on the first battery cell 11, and the remaining part of its structure is located between the first battery cell 11 and the second battery cell 12. The bus bar 40 may have a part of its structure located on the first battery cell 11, another part of its structure is located between the first battery cell 11 and the second battery cell 12, and the remaining part of its structure is located on the second battery cell 12. The entire structure of the insulating strip 30 may be located on the first battery cell 11. The insulating strip 30 may have a part of its structure located on the first battery cell 11, and the remaining part of its structure is located between the first battery cell 11 and the second battery cell 12. The insulating strip 30 may have a part of its structure located on the first battery cell 11, another part of its structure is located between the first battery cell 11 and the second battery cell 12, and the remaining part of its structure is located on the second battery cell 12.

[0064] Specifically, the insulating strip 30 is located between the bus bar 40 and the series welding ribbon 13. The entire structure of the insulating strip 30 may be located between the bus bar 40 and the series welding ribbon 13. The insulating strip 30 may also be partially located between the bus bar 40 and the series welding ribbon 13, with the remaining structure located outside the bus bar 40 and the series welding ribbon 13.

[0065] Specifically, along the direction from the first battery cell 11 to the third battery cell 21, the last electrical connection structure 111 connected by the parallel welding ribbon 50 at 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 From top to bottom, Figure 2 From left to right in the direction.

[0066] Specifically, the first section 51 and the second section 58 of the parallel welding ribbon 50 are both electrically connected to the first polarity electrical connection structure 111 of the first battery cell 11 and are respectively located on both sides of the bus bar 40 , with the first section 51 being located between the bus bar 40 and the first structure 101 ;

[0067] In other words, the parallel welding ribbon 50 electrically connects the first polarity electrical connection structure of the first battery cell 11 and the first polarity electrical connection structure of the third battery cell 21. The parallel welding ribbon 50 includes a first section 51 and a second section 58. The first section 51 and the second section 58 are both electrically connected to the first polarity electrical connection structure of the first battery cell 11 and are respectively located on the side of the bus bar 40 facing the third battery cell 21 and the side facing away from the third battery cell 21.

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

[0069] exist Figure 1 In the example of , the number of parallel welding ribbons 50 is 7. It can be understood that in other examples, the number of parallel welding ribbons 50 can be 1, 2, 3, 8 or other numbers, which are not limited here.

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

[0071] See also Figure 1 and Figure 2 In some embodiments, along the direction from the first battery cell 11 to the third battery cell 21 , the first electrical connection structure 111 to which the parallel welding ribbon 50 is connected at the third battery cell 21 is the second structure 109 ;

[0072] W1≤2W3;

[0073] Wherein, W3 is the current measured by the third section 59 of the parallel welding ribbon 50 , and the third section 59 is located between the first structure 101 and the second structure 109 .

[0074] This ensures that the current measured by the first section 51 of the parallel welding ribbon 50 is less than or equal to twice the current measured by the third section 59, leaving enough current for heat dissipation. Furthermore, this allows for more flexibility in the photovoltaic system's power generation scheduling strategy, making it more rational.

[0075] Specifically, W1 is, for example, 2W3, 1.9W3, 1.8W3, 1.7W3, 1.5W3, 1.2W3, W3, 0.8W3, 0.6W3, 0.5W3, 0.3W3, 0.2W3, and 0.1W3, but is not limited here.

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

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

[0078] See also Figure 1 and Figure 2 In some embodiments, along the direction from the first battery cell 11 to the third battery cell 21 , the first electrical connection structure 111 to which the parallel welding ribbon 50 is connected at the third battery cell 21 is the second structure 109 ;

[0079] W2<W3<W1;

[0080] Wherein, W3 is the current measured by the third section 59 of the parallel welding ribbon 50 , and the third section 59 is located between the first structure 101 and the second structure 109 .

[0081] In this way, the current measured by the third section 59 of the parallel welding ribbon 50 is smaller than the current measured by the first section 51 and larger than the current measured by the second section 58, so that the current carried by the third section 59 is within an appropriate range. This can avoid insufficient power generation efficiency of the second battery string 20 caused by the current carried by the third section 59 being too small, and can also avoid excessive heat generation and current loss caused by the current carried by the third section 59 being too large.

[0082] See also Figure 1 and Figure 2 , in some embodiments, W1>2W2.

[0083] In this way, the current measured by the first section 51 is greater than twice the current measured by the second section 58, so that the current carried by the first section 51 is larger and the power generation efficiency of the component is higher.

[0084] Specifically, W1 is, for example, 2.1W2, 2.5W2, 3W2, 5W2, 8W2, 10W2, 20W2, 50W2, 80W2, etc. This is not limited here.

[0085] See also Figure 1 and Figure 2 In some embodiments, R1<R2; wherein 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] In this way, the resistance per unit length of the first section 51 is smaller than the resistance per unit length of the second section 58 , so that the resistance per unit length of the first section 51 with a larger current is smaller, thereby reducing the larger heat loss caused by the larger current, which is beneficial to improving the power generation efficiency of the back-contact battery assembly 100.

[0087] Specifically, R1 is, for example, 0.9R2, 0.8R2, 0.6R2, 0.5R2, 0.3R2, 0.2R2, or 0.1R2, but is not limited here.

[0088] See also Figure 1 and Figure 2 In some embodiments, the resistance per unit length of the first segment 51 is smaller than the resistance per unit length of the series solder ribbon 13 .

[0089] In this way, the resistance per unit length of the first section 51 with a larger current is smaller, thereby reducing the large heat loss caused by the large current, which is beneficial to improving the power generation efficiency of the back contact battery assembly 100.

[0090] See also 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 ribbon 13 is less than or equal to 3 / 4, for example, 0.75, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, or 0.05.

[0091] In this way, the ratio of the resistance per unit length of the first section 51 to the resistance per unit length of the series welding ribbon 13 is within an appropriate range, which can avoid the poor effect of reducing heat loss caused by an excessively large ratio, and is beneficial to improving the power generation efficiency of the back-contact battery assembly 100.

[0092] See also 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 ribbon 13 is less than or equal to 1 / 2, for example, 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 section 51 to the resistance per unit length of the series solder ribbon 13 is further optimized, thereby further reducing the heat loss caused by the high current.

[0094] See also 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 ribbon 13 is less than or equal to 1 / 4, for example, 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] In this way, the ratio of the resistance per unit length of the first section 51 to the resistance per unit length of the series solder ribbon 13 is further optimized, and the heat loss caused by the high current is further reduced.

[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 ribbon 13 may be a fixed value within the aforementioned range, or may fluctuate within the aforementioned range, which is not limited herein.

[0097] See also 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 series welding ribbon 13 .

[0098] In this way, by adjusting the cross-sectional area of the first section 51 to be larger than the cross-sectional area of the series welding ribbon 13, the resistance per unit length of the first section 51 is made smaller than the resistance per unit length of the series welding ribbon 13, thereby reducing the heat loss of the first section 51 carrying a larger current.

[0099] Specifically, the ratio of the cross-sectional area of the series ribbon 13 to the cross-sectional area of the first segment 51 is less than or equal to 3 / 4. Examples include 0.75, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, and 0.05. This ensures that the ratio of the cross-sectional area of the series ribbon 13 to the cross-sectional area of the first segment 51 falls within a suitable range, thereby ensuring that the ratio of the resistance per unit length of the first segment 51 to the series ribbon 13 falls within a suitable range. This avoids the poor heat loss reduction effect caused by an excessively large ratio, thereby improving the power generation efficiency of the back-contact battery assembly 100.

[0100] Please note that the ratio of the cross-sectional area of the first section 51 to the cross-sectional area of the second section 58 may be a fixed value within the aforementioned range, or may fluctuate within the aforementioned range, which is not limited herein.

[0101] Specifically, the cross-sectional area of the first section 51 is 0.027 mm 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 series 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] See also Figure 1 and Figure 2 In some embodiments, the cross-sections of the first segment 51 and the series welding ribbon 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 series welding ribbon 13 .

[0104] In this way, by adjusting the width of the cross-section of the first segment 51 with a rectangular cross-section to be larger than the series welding ribbon 13, the cross-sectional area of the first segment 51 is made larger than the series welding ribbon 13, so that the resistance per unit length of the first segment 51 is smaller than the resistance per unit length of the series welding ribbon 13, thereby reducing the heat loss of the first segment 51 that carries a larger current.

[0105] Specifically, the ratio of the cross-sectional width of the series ribbon 13 to the cross-sectional width of the first segment 51 is less than or equal to 3 / 4. Examples include 0.75, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, and 0.05. This ensures that the ratio of the cross-sectional width of the series ribbon 13 to the cross-sectional width of the first segment 51 is within a suitable range, thereby ensuring that the ratio of the resistance per unit length of the first segment 51 to the series ribbon 13 is within a suitable range. This avoids the poor heat loss reduction effect caused by an excessively large ratio, thereby improving the power generation efficiency of the back-contact battery assembly 100.

[0106] Please note that the ratio of the width of the cross section of the first section 51 to the width of the cross section of the second section 58 may be a fixed value within the aforementioned range, or may fluctuate within the aforementioned range, which is not limited here.

[0107] Specifically, the cross-sectional width of the first section 51 is greater than or equal to 0.8 mm. Examples include 0.8 mm, 0.9 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 5 mm, 8 mm, and 10 mm. This ensures that the cross-sectional width of the first section 51 is within an appropriate range, avoiding excessive resistance and heat loss caused by an excessively small cross-sectional width of the first section 51. Preferably, the cross-sectional width of the first section 51 is between 0.8 mm and 2 mm.

[0108] Specifically, the cross-sectional width of the series soldering ribbon 13 is 0.6 mm to 1.5 mm. Examples include 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, and 1.5 mm. This ensures that the cross-sectional width of the series soldering ribbon 13 is within an appropriate range, avoiding excessive resistance, heat loss, and difficulty in soldering caused by a too small width, as well as the higher costs associated with an excessively large width.

[0109] See also Figure 1 and Figure 2 In some embodiments, the cross-sections of the first segment 51 and the series welding ribbon 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 series welding ribbon 13 .

[0110] In this way, by adjusting the thickness of the cross-section of the first segment 51 with a rectangular cross-section to be larger than the series welding ribbon 13, the cross-sectional area of the first segment 51 is made larger than the series welding ribbon 13, so that the resistance per unit length of the first segment 51 is smaller than the resistance per unit length of the series welding ribbon 13, thereby reducing the heat loss of the first segment 51 that carries a larger current.

[0111] Specifically, the ratio of the cross-sectional thickness of the series ribbon 13 to the cross-sectional thickness of the first segment 51 is less than or equal to 3 / 4. Examples include 0.75, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, and 0.05. This ensures that the ratio of the cross-sectional thickness of the series ribbon 13 to the cross-sectional thickness of the first segment 51 falls within a suitable range, thereby ensuring that the ratio of the resistance per unit length of the first segment 51 to the series ribbon 13 falls within a suitable range. This avoids the poor heat loss reduction effect caused by an excessively large ratio, thereby improving the power generation efficiency of the back-contact battery assembly 100.

[0112] Please note that the ratio of the thickness of the cross section of the first section 51 to the thickness of the cross section of the second section 58 may be a fixed value within the aforementioned range, or may fluctuate within the aforementioned range, which is not limited herein.

[0113] Specifically, the cross-sectional thickness of the first section 51 is greater than or equal to 0.11 mm. Examples include 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, and 1 mm. This ensures that the cross-sectional thickness of the first section 51 is within an appropriate range, avoiding excessive resistance and heat loss caused by a thin cross-sectional thickness of the first section 51. Preferably, the cross-sectional thickness of the first section 51 is between 0.11 mm and 0.267 mm.

[0114] Specifically, the cross-sectional thickness of the series soldering ribbon 13 is 0.08 mm to 0.20 mm. Examples include 0.08 mm, 0.09 mm, 0.1 mm, 0.11 mm, 0.13 mm, 0.15 mm, 0.18 mm, 0.19 mm, and 0.2 mm. This ensures that the cross-sectional thickness of the series soldering ribbon 13 is within an appropriate range, avoiding excessive resistance, heat loss, and difficulty in soldering caused by a too-small thickness, and also avoiding the high cost caused by an excessively large thickness.

[0115] See also Figure 1 and Figure 2 In some embodiments, the cross-sections of the first segment 51 and the series welding ribbon 13 are circular, and the diameter of the cross-section of the first segment 51 is greater than the diameter of the cross-section of the series welding ribbon 13 .

[0116] In this way, by adjusting the diameter of the cross-section of the first section 51 with a circular cross-section to be larger than the series welding ribbon 13, the cross-sectional area of the first section 51 is made larger than the series welding ribbon 13, so that the resistance per unit length of the first section 51 is smaller than the resistance per unit length of the series welding ribbon 13, thereby reducing the heat loss of the first section 51 that carries a larger current.

[0117] Specifically, the ratio of the cross-sectional diameter of the series ribbon 13 to the cross-sectional diameter of the first segment 51 is less than or equal to 3 / 4. Examples include 0.75, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, and 0.05. This ensures that the ratio of the cross-sectional diameter of the series ribbon 13 to the cross-sectional diameter of the first segment 51 is within a suitable range, thereby ensuring that the ratio of the resistance per unit length of the first segment 51 to the series ribbon 13 is within a suitable range. This avoids the poor heat loss reduction effect caused by an excessively large ratio, thereby improving the power generation efficiency of the back-contact battery assembly 100.

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

[0119] Specifically, the cross-sectional diameter of the first segment 51 is greater than or equal to 0.16 mm. Examples include 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, and 1 mm. This ensures that the cross-sectional diameter of the first segment 51 is within an appropriate range, avoiding excessive resistance and heat loss caused by an excessively small cross-sectional diameter of the first segment 51. Preferably, the cross-sectional diameter of the first segment 51 is between 0.16 mm and 0.347 mm.

[0120] Specifically, the cross-sectional diameter of the series soldering ribbon 13 is 0.12 mm to 0.26 mm. Examples include 0.12 mm, 0.13 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, and 0.26 mm. This ensures that the cross-sectional diameter of the series soldering ribbon 13 is within an appropriate range, avoiding excessive resistance, heat loss, and difficulty in soldering caused by a too small diameter, as well as the higher costs associated with an overly large diameter.

[0121] See also 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 welding ribbon 13 .

[0122] In this way, by adjusting the resistivity of the first section 51 in the parallel welding ribbon 50 to be smaller than that of the series welding ribbon 13, the resistance per unit length of the first section 51 is smaller than the resistance per unit length of the series welding ribbon 13, thereby reducing the heat loss of the first section 51 carrying a larger 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 ribbon 13 is less than or equal to 3 / 4. Examples include 0.75, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, and 0.05. 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 ribbon 13 is within a suitable range, thereby ensuring that the ratio of the resistance per unit length of the first segment 51 to the resistance per unit length of the series solder ribbon 13 is within a suitable range. This avoids the poor heat loss reduction effect caused by an excessively large ratio, thereby facilitating improved power generation efficiency of the back-contact battery assembly 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 welding ribbon 13 may be a fixed value within the aforementioned range, or may fluctuate within the aforementioned range, which is not limited here.

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

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

[0127] Specifically, the first section 51 includes at least one of a copper welding strip and a copper-aluminum welding strip.

[0128] Specifically, the series welding strip 13 includes at least one of a copper welding strip and a copper-aluminum welding strip.

[0129] In some examples, the cross-sectional area of the first segment 51 gradually increases from the third battery cell 21 to the first battery 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 while reducing material costs.

[0130] In addition, the battery assembly may also include a metal frame, a backplane, photovoltaic glass, and an adhesive film. The adhesive film can be filled between the front and back sides of the back contact solar cell, the photovoltaic glass, and adjacent solar cells. As a filler, it can be a transparent colloid with good light transmittance and aging resistance. For example, the adhesive film can be EVA film or POE film. The specific choice can be based on actual conditions and is not limited here.

[0131] Photovoltaic glass can cover the adhesive film on the front of the back-contact cell. The photovoltaic glass can be ultra-clear glass, which has high light transmittance, high transparency, and excellent physical, mechanical, and optical properties. For example, ultra-clear glass can have a light transmittance of over 92%, protecting the back-contact cell while minimizing the impact on the efficiency of the cell. The adhesive film also bonds the photovoltaic glass and the back-contact cell together, providing sealing, insulation, and waterproofing.

[0132] The backsheet can be attached to the film on the back of the back-contact solar cell. It protects and supports the back-contact solar cell and offers reliable insulation, water resistance, and aging resistance. Multiple backsheet options are available, typically including tempered glass, organic glass, and aluminum alloy TPT composite film. The specific backsheet configuration varies depending on the specific situation and is not limited here. The backsheet, back-contact solar cell, film, and photovoltaic glass assembly can be mounted on a metal frame. The metal frame serves as the primary external support structure for the entire solar cell assembly and provides stable support and installation for the assembly. For example, the metal frame allows the assembly to be mounted in the desired location.

[0133] The photovoltaic system of the embodiment of the present application includes any one of the above-mentioned back-contact cell assemblies 100 .

[0134] In the photovoltaic system of the embodiment of the present application, since the busbar 40 in the back-contact cell module 100 is disposed on the first cell 11, the busbar 40 electrically isolates the series welding ribbon 13 via the insulating strip 30, and the busbar 40 electrically connects to the parallel welding ribbon 50, the busbar 40 can be disposed on the back of the first cell 11, making the busbar 40 difficult to observe from the front of the module, resulting in a better visual effect. This also frees up more space for the cells, thereby increasing the module's power generation efficiency. Furthermore, since the current measured in the first section 51 of the parallel welding ribbon 50, which is closer to the second cell string 20, is greater than the current measured in the second section 58 when AM1.5 light is applied to the module, the section of the welding ribbon with higher current can be placed closer to the second cell string 20, connecting with the large amount of current generated by the second cell string 20 and transmitting it to the busbar 40, thereby improving the busbar 40's current collection effect.

[0135] In this embodiment, the photovoltaic system can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water surface power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array can 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 junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter to be converted into the alternating current required by the mains power grid and then connected to the mains power network to achieve solar power supply.

[0136] Throughout this specification, reference to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with an embodiment or example is included in at least one embodiment or example of the present application. In this specification, the illustrative use of the above terms does 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 any one or more embodiments or examples.

[0137] In addition, the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A back contact battery assembly, characterized in that: include: A first battery string and a second battery string each include a plurality of back-contact battery cells connected in series, wherein 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 welding ribbon, wherein the series welding ribbon 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 electrically connecting the first battery cell and the plurality of first polarity electrical connection structures of the third battery cell; a bus bar, provided on the first battery cell and electrically connected to the parallel welding ribbon; an insulating strip, provided between the bus bar and the series welding strip, electrically isolating the bus bar from the series welding strip; Along the direction from the first battery cell to the third battery cell, the last electrical connection structure of the parallel welding ribbon connected to the first battery cell is a first structure; The first and second sections of the parallel welding ribbon are both electrically connected to the electrical connection structure of the first polarity of the first battery cell and are respectively located on both sides of the bus bar, with the first section being located between the bus bar and the first structure; When AM1.5 light is applied to the back contact cell assembly, W1>W2; Wherein, W1 is the current measured in the first section, and W2 is the current measured in the second section.

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 connected by the parallel welding ribbon at the third battery cell is the second structure; W1≤2W3; Wherein, W3 is the current measured at the third section of the parallel welding strip, and the third section 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 connected by the parallel welding ribbon at the third battery cell is the second structure; W2<W3<W1; Wherein, W3 is the current measured at the third section of the parallel welding strip, and the third section is located between the first structure and the second structure.

4. The back contact battery assembly according to claim 1, wherein: W1>2W2.

5. The back contact battery assembly according to claim 1, characterized in that R1<R2; Here, 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 smaller than the resistance per unit length of the series welding ribbon.

7. The back contact battery assembly according to claim 6, characterized in that A ratio of the resistance per unit length of the first segment to the resistance per unit length of the series welding ribbon 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 series welding ribbon.

9. The back contact battery assembly according to claim 6, characterized in that: The cross-sections of the first section and the series welding strip are rectangular, and the width of the cross-section of the first section is greater than the width of the cross-section of the series welding strip.

10. The back contact battery assembly according to claim 6, characterized in that: The cross-sections of the first section and the series welding ribbon are rectangular, and the thickness of the cross-section of the first section is greater than the thickness of the cross-section of the series welding ribbon.

11. The back contact battery assembly according to claim 6, characterized in that: The cross-sections of the first section and the series welding ribbon are circular, and the diameter of the cross-section of the first section is larger than the diameter of the cross-section of the series welding ribbon.

12. The back contact battery assembly according to claim 6, characterized in that: The resistivity per unit length of the first segment is smaller than the resistivity per unit length of the series welding ribbon.

13. A photovoltaic system, characterized in that: A back contact battery assembly comprising any one of claims 1-12.

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