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 which respectively comprise a plurality of back contact battery pieces which are connected in series; the first battery string comprises a first battery piece and a second battery piece, and the second battery string comprises a third battery piece; at least part of the structure of the bus bar is arranged on the second battery piece; the insulating strip is used for electrically isolating the welding strip connected with the second battery piece from the bus bar; the parallel welding strip is connected with the bus bar and is connected with the first polarity electric connection structure of the first battery piece and the third battery piece; the parallel welding strip comprises a first section, a second section and a third section, the first section is located on the side, close to the bus bar, of the first structure, the second section is located between the second structure and the third structure, and the third section is located between the first structure and the second 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 battery assembly and a photovoltaic system. Background Art

[0002] Solar cell power generation is a sustainable clean energy source, which can convert sunlight into electrical energy by utilizing the photovoltaic effect of the semiconductor p-n junction.

[0003] In related technologies, a plurality of back-contact battery wafers are usually connected by welding tapes, and then the welding tapes are connected by busbars to realize the electrical connection of each back-contact battery wafer. However, the busbars are usually staggered from the battery wafers and are easily observed from the front of the assembly, resulting in a poor visual effect in appearance. Moreover, the busbars will occupy the space for placing the battery wafers in the assembly, resulting in a low power generation efficiency of the assembly.

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

[0005] The present application provides a back-contact battery 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 battery 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, both including a plurality of serially connected back-contact battery wafers; the first battery string includes a first battery wafer and a second battery wafer, the second battery string includes a third battery wafer, and the first battery wafer is located between the second battery wafer and the third battery wafer;

[0008] A busbar, at least a part of the structure is disposed on the second battery wafer;

[0009] An insulating strip for electrically isolating the welding tape connected to the second battery wafer from the busbar;

[0010] A parallel welding tape for electrically connecting the busbar and electrically connecting a plurality of first-polarity electrical connection structures of the first battery wafer and the third battery wafer; along the direction from the first battery wafer to the third battery wafer, the first and last electrical connection structures connected to the first battery wafer by the parallel welding tape are a first structure and a second structure respectively, and the first electrical connection structure connected to the third battery wafer is a third structure;

[0011] The parallel welding ribbon includes a first section, a second section, and a third section. The first section is located on the side of the first structure close to the bus bar. The second section is located between the second structure and the third structure. The third section is located between the first structure and the second structure;

[0012] When the back contact battery assembly is irradiated with AM1.5 light, L1 > L2;

[0013] Wherein, L1 is the current measured in the first section, and L2 is the current measured in the second section.

[0014] Specifically, the first battery string includes a series welding ribbon that connects the electrical connection structure of the second polarity of the first battery cell and the electrical connection structure of the first polarity of the second battery cell. Along the direction from the second battery cell to the first battery cell, the last electrical connection structure where the series welding ribbon is connected to the second battery cell is the fourth structure, and the first electrical connection structure where the series welding ribbon is connected to the first battery cell is the fifth structure;

[0015] L1 = L2 + L3;

[0016] Wherein, L3 is the current measured in the connection section of the series welding ribbon, and the connection section is located between the fourth structure and the fifth structure.

[0017] Specifically, L1 ≤ 2L2.

[0018] Specifically, R1 < R2;

[0019] Wherein, R1 is the resistance per unit length of the first section, and R2 is the resistance per unit length of the second section.

[0020] Specifically, the first battery string includes a series welding ribbon that connects the electrical connection structure of the second polarity of the first battery cell and the electrical connection structure of the first polarity of the second battery cell; the resistance per unit length of the first section is less than the resistance per unit length of the series welding ribbon.

[0021] Specifically, the ratio of the resistance per unit length of the first section to the resistance per unit length of the series welding ribbon is less than or equal to 3 / 4.

[0022] Specifically, the cross-sectional area of the first section is greater than the cross-sectional area of the series welding ribbon.

[0023] 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.

[0024] Specifically, the cross-sections of the first section and the series connection bus bar 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 connection bus bar.

[0025] Specifically, the cross-sections of the first section and the series connection bus bar are circular, and the diameter of the cross-section of the first section is greater than the diameter of the cross-section of the series connection bus bar.

[0026] Specifically, the resistivity per unit length of the first section is less than the resistivity per unit length of the series connection bus bar.

[0027] This application also provides a photovoltaic system, which includes the back contact battery assembly described above.

[0028] In the back contact battery assembly and the photovoltaic system of the embodiments of this application, since at least part of the structure of the bus bar is arranged on the second cell and the insulating strip electrically isolates the bus bar connected to the second cell from the bus bar, the bus bar can be arranged on the back of the cell, making it difficult to observe the bus bar from the front of the assembly and achieving a better visual effect in appearance. Moreover, more space can be vacated to place the cells, increasing the power generation efficiency of the assembly. At the same time, when the assembly is irradiated with AM1.5 light, the current measured in the first section of the parallel connection bus bar connected to the bus bar is greater than the current measured in the second section connected to the third cell. Therefore, the bus bar can be made closer to the bus bar segment with a larger current, reducing the electrical losses and the heating of the bus bar caused by long-distance transmission of large currents, and improving the power generation efficiency and reliability of the assembly during use.

[0029] Additional aspects and advantages of this application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of this application. Description of the Drawings

[0030] Figure 1 is a schematic structural diagram of a back contact battery assembly provided by an embodiment of this application;

[0031] Figure 2 is a schematic structural diagram of a back contact battery assembly provided by an embodiment of this application;

[0032] Main Element Symbol Description:

[0033] Back contact battery assembly 100, first battery string 10, first cell 11, electrical connection structure 111, second cell 12, series connection bus bar 13, connection section 131, second battery string 20, third cell 21, insulating strip 30, bus bar 40, parallel connection bus bar 50, first section 51, second section 52, third section 53, first structure 101, second structure 102, third structure 103, fourth structure 104, fifth structure 105. Detailed Embodiments

[0034] In order to make the objectives, technical solutions and advantages of the present application more clear and understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, where 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 by referring to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0035] In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "back", "front", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present 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 thus should not be construed as a limitation to the present application.

[0036] In the present application, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the horizontal height of the first feature is lower than that of the second feature.

[0037] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. To simplify the disclosure of the present application, components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present application. In addition, the present application may repeat reference numerals and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not 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 of ordinary skill in the art can be aware of the application of other processes and / or the use scenarios of other materials.

[0038] Please refer to Figure 1 and Figure 2 , the back-contact battery assembly 100 of the embodiment of the present application includes:

[0039] The first battery string 10 and the second battery string 20 both include a plurality of back-contact solar cells connected in series. The first battery string 10 includes a first solar cell 11 and a second solar cell 12, and the second battery string 20 includes a third solar cell 21. The first solar cell 11 is located between the second solar cell 12 and the third solar cell 21.

[0040] The bus bar 40 has at least part of its structure disposed on the second solar cell 12.

[0041] The insulating strip 30 electrically isolates the solder tape connected to the second solar cell 12 from the bus bar 40.

[0042] The parallel solder tape 50 is electrically connected to the bus bar 40 and electrically connected to a plurality of first-polarity electrical connection structures 111 of the first solar cell 11 and the third solar cell 21. Along the direction from the first solar cell 11 to the third solar cell 21, the first and last electrical connection structures 111 connected by the parallel solder tape 50 to the first solar cell 11 are a first structure 101 and a second structure 102 respectively, and the first electrical connection structure 111 connected by the parallel solder tape 50 to the third solar cell 21 is a third structure 103.

[0043] The parallel solder tape 50 includes a first section 51, a second section 52, and a third section 53. The first section 51 is located on the side of the first structure 101 closer to the bus bar 40, the second section 52 is located between the second structure 102 and the third structure 103, and the third section 53 is located between the first structure 101 and the second structure 102.

[0044] When the back-contact battery module is subjected to AM1.5 illumination, L1 > L2.

[0045] Wherein, L1 is the current measured in the first section 51, and L2 is the current measured in the second section 52.

[0046] In the back-contact battery module 100 according to the embodiment of the present application, since at least part of the structure of the bus bar 40 is disposed on the second solar cell 12 and the insulating strip 30 electrically isolates the solder tape connected to the second solar cell 12 from the bus bar 40, the bus bar 40 can be disposed on the back of the solar cell, making it difficult to observe the bus bar 40 from the front of the module and achieving a better visual effect in appearance. Moreover, more space can be vacated to place solar cells, increasing the power generation efficiency of the module. At the same time, when the module is subjected to AM1.5 illumination, the current measured in the first section 51 of the parallel solder tape 50 connected to the bus bar 40 is greater than the current measured in the second section 52 connected to the third solar cell 21. Therefore, the solder tape section with a larger current can be closer to the bus bar 40, reducing the electrical losses and solder tape heating caused by long-distance transmission of large currents, and improving the power generation efficiency and reliability of the module during use.

[0047] Specifically, the back-contact battery assembly 100 includes a first series structure and a second series structure. The first series structure and the second series structure are connected in parallel with each other and both include a plurality of battery strings arranged in a first direction. Each battery string includes a plurality of back-contact battery cells arranged in a second direction, and the second direction intersects the first direction. The battery strings of the first series structure are the first battery strings 10. The battery strings of the second series structure are the second battery strings 20. The first battery strings 10 and the second battery strings 20 are arranged in the second direction.

[0048] 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.

[0049] Specifically, the back-contact battery cells may include main-grid back-contact battery cells or may include non-main-grid back-contact battery cells. The specific form of the back-contact battery cells is not limited herein.

[0050] Specifically, the back-contact battery cells may include grid lines of a first polarity and grid lines of a second polarity, and the first polarity is opposite to the second polarity. The back-contact battery cells may include a plurality of electrical connection structures 111. The electrical connection structures 111 are provided on the grid lines and are used for electrically connecting the solder tapes. The electrical connection structures 111 include at least one of a pad, solder paste, conductive adhesive, and grid line segments. It can be 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.

[0051] Please note that the explanations and descriptions regarding the back-contact battery cells apply to the first battery cell 11, the second battery cell 12, and the third battery cell 21.

[0052] Specifically, the first battery string 10 includes a first battery cell 11 and a second battery cell 12, the second battery string 20 includes a third battery cell 21, and 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.

[0053] Specifically, at least part of the structure of the bus bar 40 is disposed on the second battery cell 12, and the insulating strip 30 electrically isolates the solder tape connected to the second battery cell 12 from the bus bar 40. Further, the insulating strip 30 is disposed on the side of the solder tape connected to the second battery cell 12 that faces away from the second battery cell 12, and the bus bar 40 is disposed on the side of the insulating strip 30 that faces away from the second battery cell 12. In other words, the insulating strip 30 and the bus bar 40 are sequentially stacked on the side of the solder tape connected to the second battery cell 12 that faces away from the second battery cell 12. The insulating strip 30 is located between the bus bar 40 and the solder tape connected to the second battery cell 12.

[0054] Specifically, the entire structure of the bus bar 40 may be located on the second battery cell 12. Part of the structure of the bus bar 40 may be located on the second battery cell 12, and other parts of the structure may be located between the first battery cell 11 and the second battery cell 12. Part of the structure of the bus bar 40 may be located on the second battery cell 12, another part of the structure may be located between the first battery cell 11 and the second battery cell 12, and the remaining part of the structure may be located on the first battery cell 11. The entire structure of the insulating strip 30 may be located on the second battery cell 12. Part of the structure of the insulating strip 30 may be located on the second battery cell 12, and other parts of the structure may be located between the first battery cell 11 and the second battery cell 12. Part of the structure of the insulating strip 30 may be located on the second battery cell 12, another part of the structure may be located between the first battery cell 11 and the second battery cell 12, and the remaining part of the structure may be located on the first battery cell 11.

[0055] In the first example, the entire structure of the insulating strip 30 and the entire structure of the bus bar 40 are located on the second battery cell 12. In the second example, the entire structure of the bus bar 40 is located on the second battery cell 12, part of the structure of the insulating strip 30 is located on the second battery cell 12, and the other structure of the insulating strip 30 is located between the first battery cell 11 and the second battery cell 12. In the third example, the entire structure of the bus bar 40 is located on the second battery cell 12, part of the structure of the insulating strip 30 is located on the second battery cell 12, another part of the structure is located between the first battery cell 11 and the second battery cell 12, and the other structure is located on the first battery cell 11. In the fourth example, part of the structure of the bus bar 40 is located on the second battery cell 12, and other parts of the structure are located between the first battery cell 11 and the second battery cell 12. Part of the structure of the insulating strip 30 is located on the second battery cell 12, another part of the structure is located between the first battery cell 11 and the second battery cell 12, and the remaining part of the structure is located on the second battery cell 12. In the fifth example, part of the structure of the bus bar 40 is located on the second battery cell 12, another part of the structure is located between the first battery cell 11 and the second battery cell 12, and the remaining part of the structure is located on the first battery cell 11. Part of the structure of the insulating strip 30 is located on the second battery cell 12, another part of the structure is located between the first battery cell 11 and the second battery cell 12, and the remaining part of the structure is located on the first battery cell 11.

[0056] Specifically, the insulating strip 30 includes at least one of POE, EVA, and EPE.

[0057] Specifically, the electrical connection includes at least one of welding, conductive adhesive bonding, and physical conductive contact. No limitation is made here.

[0058] Specifically, the parallel welding strip 50 is electrically connected to the bus bar 40 and electrically connected to a plurality of first-polarity electrical connection structures 111 of the first solar cell 11 and the third solar cell 21. Further, the parallel welding strip 40 can be welded to, adhesively bonded with conductive adhesive to, physically conductively contacted with, etc. the bus bar. The parallel welding strip 40 can be welded to, adhesively bonded with conductive adhesive to, physically conductively contacted with, etc. the first-polarity electrical connection structure 111 of the first solar cell 11. The parallel welding strip 40 can be welded to, adhesively bonded with conductive adhesive to, physically conductively contacted with, etc. the first-polarity electrical connection structure 111 of the third solar cell 21. No limitation is made here.

[0059] Specifically, along the direction from the first solar cell 11 to the third solar cell 21, the first and last electrical connection structures 111 where the parallel welding strip 50 is connected to the first solar cell 11 are the first structure 101 and the second structure 102 respectively, and the first electrical connection structure 111 where the parallel welding strip 50 is connected to the third solar cell 21 is the third structure 103. It can be understood that the direction from the first solar cell 11 to the third solar cell 21 is also Figure 1 the direction from top to bottom in Figure 2 the direction from left to right in

[0060] Specifically, the parallel welding strip 50 includes a first section 51, a second section 52, and a third section 53. The first section 51 is located on the side of the first structure 101 close to the bus bar 40. The second section 52 is located between the second structure 102 and the third structure 103. The third section 53 is located between the first structure 101 and the second structure 102. That is, the first section 51 and the second section 52 are respectively located on both sides of the third section 53. In other words, the first section 51, the first structure 101, the third section 53, the second structure 102, the second section 52, and the third structure 103 are arranged in sequence.

[0061] In Figure 1 the example, the number of the parallel welding strips 50 is 7. It can be understood that in other examples, the number of the parallel welding strips 50 can be 1, 2, 3, 8, or other numbers, and no limitation is made here.

[0062] Specifically, the parallel welding strip 50 is electrically connected to the bus bar 40 and the electrical connection structures with the same polarity in the first solar cell 11 and the third solar cell 21. That is, the parallel welding strip 50 connects the first solar cell 11 and the third solar cell 21 in parallel.

[0063] Specifically, in the test of the back-contact battery module 100, under standard test conditions, L1 > L2. The standard test conditions are to conduct the test under AM1.5, 1000 W / m 2 , and 25 °C.

[0064] Please refer to Figure 1 and Figure 2 , in some embodiments, the first battery string 10 includes a series welding strip 13. The series welding strip 13 connects the electrical connection structure 111 of the second polarity of the first battery cell 11 and the electrical connection structure 111 of the first polarity of the second battery cell 12. Along the direction from the second battery cell 12 to the first battery cell 11, the last electrical connection structure 111 where the series welding strip 13 is connected to the second battery cell 12 is the fourth structure 104, and the first electrical connection structure 111 where the series welding strip 13 is connected to the first battery cell 11 is the fifth structure 105;

[0065] L1 = L2 + L3;

[0066] wherein, L3 is the current measured on the connection section 131 of the series welding strip 13, and the connection section 131 is located between the fourth structure 104 and the fifth structure 105.

[0067] In this way, the current measured on the first section 51 is equal to the sum of the current measured on the second section 52 and the current measured on the series welding strip 13, so that the currents of the first battery string 10 and the second battery string 20 are all collected to the bus bar 40 through the first section 51, which is relatively concentrated, making the bus bar 40 better at collecting current.

[0068] In Figure 1 example, the number of series welding strips 13 is 7. It can be understood that in other examples, the number of series welding strips 13 can be 1, 2, 3, 8, or other numbers, which are not limited herein.

[0069] It can be understood that the series welding strip 13 connects the electrical connection structure of the second polarity of the first battery cell 11 and the electrical connection structure of the first polarity of the second battery cell 12, that is, the series welding strip 13 connects the first battery cell 11 and the second battery cell 12 in series.

[0070] It can be understood that since the insulating strip 30 electrically isolates the welding strip connected to the second battery cell 12 from the bus bar 40, and the bus bar 40 is electrically connected to the first section 51 of the parallel welding strip 50, the current L2 measured on the second section 52, which is also the total current of the second battery string 20, will be delivered to the bus bar 40 through the first section 51 that is electrically connected to the second section 52. Second, the series welding strip 13 connects the first battery cell 11 and the second battery cell 12 in series, and the current L3 measured on the series welding strip 13 will be delivered to the first section 51 that is electrically connected to the first battery cell 11 through the series welding strip 13 and the first battery cell 11. Therefore, L1 = L2 + L3.

[0071] Please refer to Figure 1 and Figure 2 , in some embodiments, L1 ≤ 2L2.

[0072] In this way, the current measured in the first section 51 is less than or equal to twice the current measured in the second section 52, and a current margin can be reserved for heat loss. Moreover, a floating space can be reserved for the power generation scheduling strategy of the photovoltaic system, making the power generation scheduling of the photovoltaic system more reasonable.

[0073] Specifically, L1 is, for example, 2L2, 1.8L2, 1.7L2, 1.5L2, 1.2L2, L2, 0.8L2, 0.6L2, 0.5L2, 0.3L2, 0.2L2, 0.1L2. It is not limited herein.

[0074] Please refer to Figure 1 and Figure 2 , in some embodiments, R1 < R2; where R1 is the resistance per unit length of the first section 51, and R2 is the resistance per unit length of the second section 52.

[0075] In this way, the resistance per unit length of the first section 51 is less than the resistance per unit length of the second section 52, so that 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 larger current, which is beneficial to improving the power generation efficiency of the back-contact battery module 100.

[0076] Specifically, R1 is, for example, 0.9R2, 0.8R2, 0.6R2, 0.5R2, 0.3R2, 0.2R2, 0.1R2. It is not limited herein.

[0077] Please refer to Figure 1 and Figure 2 , in some embodiments, the first battery string 10 includes a series welding tape 13, and the series welding tape 13 connects the electrical connection structure of the second polarity of the first battery cell 11 and the electrical connection structure of the first polarity of the second battery cell 12; the resistance per unit length of the first section 51 is less than the resistance per unit length of the series welding tape 13.

[0078] 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 larger current, which is beneficial to improving the power generation efficiency of the back-contact battery module 100.

[0079] Specifically, the first section 51 is located on the first battery cell 11 and on the side of the bus bar 40 facing the third battery cell 21.

[0080] Please refer to Figure 1 and Figure 2, in some embodiments, the ratio of the resistance per unit length of the first section 51 to the resistance per unit length of the series connecting 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, 0.05.

[0081] In this way, making the ratio of the resistance per unit length of the first section 51 to the resistance per unit length of the series connecting strip 13 within a suitable range can avoid the poor effect of reducing heat loss caused by too large a ratio, which is beneficial to improving the power generation efficiency of the back contact battery module 100.

[0082] Please refer to Figure 1 and Figure 2 , in some embodiments, the ratio of the resistance per unit length of the first section 51 to the resistance per unit length of the series connecting 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, 0.05.

[0083] In this way, further optimizing the ratio of the resistance per unit length of the first section 51 to the resistance per unit length of the series connecting strip 13 can further reduce the heat loss caused by large current.

[0084] Please refer to Figure 1 and Figure 2 , in some embodiments, the ratio of the resistance per unit length of the first section 51 to the resistance per unit length of the series connecting 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, 0.02.

[0085] In this way, even further optimizing the ratio of the resistance per unit length of the first section 51 to the resistance per unit length of the series connecting strip 13 can even further reduce the heat loss caused by large current.

[0086] Please note that the ratio of the resistance per unit length of the first section 51 to the resistance per unit length of the series connecting strip 13 can be a fixed value within the aforementioned range or can fluctuate within the aforementioned range, which is not limited herein.

[0087] Please refer to Figure 1 and Figure 2 , in some embodiments, the cross-sectional area of the first section 51 is larger than the cross-sectional area of the series connecting strip 13.

[0088] 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 connecting strip 13, the resistance per unit length of the first section 51 is made less than the resistance per unit length of the series connecting strip 13, so that the heat loss of the first section 51 carrying a large current can be reduced.

[0089] Specifically, the ratio of the cross-sectional area of the series soldering ribbon 13 to the cross-sectional area of the first section 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, 0.05. In this way, the ratio of the cross-sectional area of the series soldering ribbon 13 to the cross-sectional area of the first section 51 is within a suitable range, so that the ratio of the resistance per unit length of the first section 51 to the series soldering ribbon 13 is within a suitable range, which can avoid the poor effect of reducing heat loss caused by too large a ratio and is beneficial to improving the power generation efficiency of the back contact battery module 100.

[0090] Please note that the ratio of the cross-sectional area of the first section 51 to the cross-sectional area of the second section 52 can be a fixed value within the aforementioned range or can fluctuate within the aforementioned range, and is not limited herein.

[0091] Specifically, the cross-sectional area of the first section 51 is 0.027 mm 2 -0.3 mm 2 . For example, it is 0.027 mm 2 , 0.029 mm 2 , 0.03 mm 2 , 0.05 mm 2 , 0.1 mm 2 , 0.15 mm 2 , 0.2 mm 2 , 0.25 mm 2 , 0.27 mm 2 , 0.3 mm 2 .

[0092] Specifically, the cross-sectional area of the series soldering ribbon 13 is 0.02 mm 2 -0.2 mm 2 . For example, it is 0.02 mm 2 , 0.022 mm 2 , 0.03 mm 2 , 0.08 mm 2 , 0.1 mm 2 , 0.15 mm 2 , 0.18 mm 2 , 0.2 mm 2 .

[0093] Please refer to Figure 1 and Figure 2 , in some embodiments, the cross-sections of the first section 51 and the series soldering ribbon 13 are rectangular, and the width of the cross-section of the first section 51 is greater than the width of the cross-section of the series soldering ribbon 13.

[0094] In this way, by adjusting the width of the cross-section of the first section 51 with a rectangular cross-section to be larger than that of the series connection ribbon 13, the cross-sectional area of the first section 51 is made larger than that of the series connection ribbon 13, so that the resistance per unit length of the first section 51 is less than that of the series connection ribbon 13, thereby reducing the heat loss of the first section 51 carrying a large current.

[0095] Specifically, the ratio of the width of the cross-section of the series connection ribbon 13 to the width of the cross-section of the first section 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, 0.05. In this way, the ratio of the width of the cross-section of the series connection ribbon 13 to the width of the cross-section of the first section 51 is within a suitable range, so that the ratio of the resistance per unit length of the first section 51 to that of the series connection ribbon 13 is within a suitable range, which can avoid the poor effect of reducing heat loss caused by too large a ratio and is beneficial to improving the power generation efficiency of the back contact battery module 100.

[0096] 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 52 can be a fixed value within the aforementioned range or can fluctuate within the aforementioned range, which is not limited here.

[0097] Specifically, the width of the cross-section of the first section 51 is greater than or equal to 0.8 mm. For example, it is 0.8 mm, 0.9 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 5 mm, 8 mm, 10 mm. In this way, the width of the cross-section of the first section 51 is within a suitable range, which can avoid too large resistance and too large heat loss caused by too small width of the cross-section of the first section 51. Preferably, the width of the cross-section of the first section 51 is 0.8 mm - 2 mm.

[0098] Specifically, the width of the cross-section of the series connection ribbon 13 is 0.6 mm to 1.5 mm. For example, it is 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, 1.5 mm. In this way, the width of the cross-section of the series connection ribbon 13 is within a suitable range, which can avoid too large resistance, too large heat loss, and difficulty in welding caused by too small width, and can also avoid too high cost caused by too large width.

[0099] Please refer to Figure 1 and Figure 2 In some embodiments, the cross-sections of the first section 51 and the series connection ribbon 13 are rectangular, and the thickness of the cross-section of the first section 51 is greater than the thickness of the cross-section of the series connection ribbon 13.

[0100] Thus, by adjusting the thickness of the cross-section of the first section 51 with a rectangular cross-section to be larger than that of the series connection strip 13, the cross-sectional area of the first section 51 is made larger than that of the series connection strip 13, so that the resistance per unit length of the first section 51 is less than that of the series connection strip 13, thereby reducing the heat loss of the first section 51 carrying a large current.

[0101] Specifically, the ratio of the thickness of the cross-section of the series connection strip 13 to the thickness of the cross-section of the first section 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, 0.05. In this way, the ratio of the thickness of the cross-section of the series connection strip 13 to the thickness of the cross-section of the first section 51 is within a suitable range, so that the ratio of the resistance per unit length of the first section 51 to that of the series connection strip 13 is within a suitable range, which can avoid the poor effect of reducing heat loss caused by too large a ratio and is beneficial to improving the power generation efficiency of the back contact battery module 100.

[0102] 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 52 can be a fixed value within the aforementioned range or can fluctuate within the aforementioned range, and is not limited herein.

[0103] Specifically, the thickness of the cross-section of the first section 51 is greater than or equal to 0.11 mm. For example, it is 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, 1 mm. In this way, the thickness of the cross-section of the first section 51 is within a suitable range, which can avoid too large resistance and too large heat loss caused by too small thickness of the cross-section of the first section 51. Preferably, the thickness of the cross-section of the first section 51 is 0.11 mm - 0.267 mm.

[0104] Specifically, the thickness of the cross-section of the series connection strip 13 is 0.08 mm to 0.20 mm. For example, it is 0.08 mm, 0.09 mm, 0.1 mm, 0.11 mm, 0.13 mm, 0.15 mm, 0.18 mm, 0.19 mm, 0.2 mm. In this way, the thickness of the cross-section of the series connection strip 13 is within a suitable range, which can avoid too large resistance, too large heat loss, and difficulty in welding caused by too small thickness, and can also avoid too high cost caused by too large thickness.

[0105] Please refer to Figure 1 and Figure 2 , in some embodiments, the cross-sections of the first section 51 and the series connection strip 13 are circular, and the diameter of the cross-section of the first section 51 is greater than the diameter of the cross-section of the series connection strip 13.

[0106] Thus, by adjusting the diameter of the cross-section of the first section 51 with a circular cross-section to be larger than that of the series soldering tape 13, the cross-sectional area of the first section 51 is made larger than that of the series soldering tape 13, so that the resistance per unit length of the first section 51 is less than that of the series soldering tape 13, thereby reducing the heat loss of the first section 51 carrying a large current.

[0107] Specifically, the ratio of the diameter of the cross-section of the series soldering tape 13 to the diameter of the cross-section of the first section 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, 0.05. Thus, the ratio of the diameter of the cross-section of the series soldering tape 13 to the diameter of the cross-section of the first section 51 is within a suitable range, so that the ratio of the resistance per unit length of the first section 51 to that of the series soldering tape 13 is within a suitable range, which can avoid the poor effect of reducing heat loss caused by too large a ratio and is beneficial to improving the power generation efficiency of the back-contact battery module 100.

[0108] 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 52 can be a fixed value within the aforementioned range or can fluctuate within the aforementioned range, which is not limited herein.

[0109] Specifically, the diameter of the cross-section of the first section 51 is greater than or equal to 0.16 mm. For example, it is 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, 1 mm. Thus, the diameter of the cross-section of the first section 51 is within a suitable range, which can avoid too large resistance and too large heat loss caused by too small diameter of the cross-section of the first section 51. Preferably, the diameter of the cross-section of the first section 51 is 0.16 mm - 0.347 mm.

[0110] Specifically, the diameter of the cross-section of the series soldering tape 13 is 0.12 mm to 0.26 mm. For example, it is 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, 0.26 mm. Thus, the diameter of the cross-section of the series soldering tape 13 is within a suitable range, which can avoid too large resistance, too large heat loss, and difficulty in soldering caused by too small diameter, and can also avoid too high cost caused by too large diameter.

[0111] Please refer to Figure 1 and Figure 2 , in some embodiments, the resistivity per unit length of the first section 51 is less than the resistivity per unit length of the series soldering tape 13.

[0112] Thus, by adjusting the resistivity of the first section 51 in the parallel busbar 50 to be smaller than that of the series busbar 13, the resistance per unit length of the first section 51 is made smaller than that of the series busbar 13, thereby reducing the heat loss of the first section 51 carrying a large current.

[0113] Specifically, the ratio of the resistivity per unit length of the first section 51 to the resistivity per unit length of the series busbar 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, 0.05. In this way, the ratio of the resistivity per unit length of the first section 51 to the resistivity per unit length of the series busbar 13 is within a suitable range, so that the ratio of the resistance per unit length of the first section 51 to the series busbar 13 is within a suitable range, which can avoid the poor effect of reducing heat loss caused by too large a ratio and is beneficial to improving the power generation efficiency of the back-contact battery module 100.

[0114] Please note that the ratio of the resistivity per unit length of the first section 51 to the resistivity per unit length of the series busbar 13 can be a fixed value within the aforementioned range or can fluctuate within the aforementioned range, and is not limited herein.

[0115] Specifically, the resistivity per unit length of the first section 51 is 1.6×10 -8 Ω·m - 2.82×10 -8 Ω·m.

[0116] Specifically, the resistivity per unit length of the series busbar 13 is 1.68×10 -8 Ω·m - 2.82×10 -8 Ω·m.

[0117] Specifically, the first section 51 includes at least one of a copper busbar and a copper-aluminum busbar.

[0118] Specifically, the series busbar 13 includes at least one of a copper busbar and a copper-aluminum busbar.

[0119] In some examples, along the direction from the third cell 21 to the first cell 11, the cross-sectional area of the first section 51 gradually increases. In this way, the gradual change of the cross-sectional area of the first section 51 adapts to the gradual change of the current, reducing the material cost while reducing the heat loss.

[0120] In addition, the battery module may further include a metal frame, a backsheet, a photovoltaic glass, and an encapsulant film. The encapsulant film can be filled between the front and back of the back-contact cells and the photovoltaic glass, adjacent cells, etc. As a filler, it can be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulant film can use an EVA encapsulant film or a POE encapsulant film, and can be specifically selected according to the actual situation, and is not limited herein.

[0121] The photovoltaic glass can be covered on the adhesive film on the front side of the back-contact cell. The photovoltaic glass can be ultra-white glass, which has high light transmittance, high transparency, and excellent physical, mechanical, and optical properties. For example, the light transmittance of the ultra-white glass can reach more than 92%, and it can protect the back-contact cell without affecting its efficiency as much as possible. At the same time, the adhesive film can bond the photovoltaic glass and the back-contact cell together, and the presence of the adhesive film can seal and insulate the back-contact cell and prevent water and moisture.

[0122] The backsheet can be attached to the adhesive film on the back of the back-contact cell. The backsheet can protect and support the back-contact cell, and has reliable insulation, water resistance, and aging resistance. There are multiple choices for the backsheet, which can usually be tempered glass, plexiglass, aluminum alloy TPT composite film, etc., and its specific settings can be determined according to specific circumstances and are not limited here. The overall structure composed of the backsheet, back-contact cell, adhesive film, and photovoltaic glass can be set on a metal frame. The metal frame is the main external support structure of the entire battery module, and can stably support and install the battery module. For example, the battery module can be installed at the required installation position through the metal frame.

[0123] The photovoltaic system of the embodiment of the present application includes the back-contact battery module 100 of any one of the above.

[0124] In the photovoltaic system of the embodiment of the present application, since at least part of the structure of the busbar 40 in the back-contact battery module 100 is arranged on the second cell 12 and the insulating strip 30 electrically isolates the solder tape connected to the second cell 12 from the busbar 40, the busbar 40 can be arranged on the back of the cell, making it difficult to observe the busbar 40 from the front of the module and achieving a better visual effect in appearance. Moreover, more space can be vacated to place the cells, increasing the power generation efficiency of the module. At the same time, when the module is irradiated with AM1.5 light, the current measured in the first section 51 of the parallel solder tape 50 connected to the busbar 40 is greater than the current measured in the second section 52 connected to the third cell 21. Therefore, the solder tape section with a larger current can be closer to the busbar 40, reducing the electrical losses and solder tape heating caused by long-distance transmission of large currents, and improving the power generation efficiency and reliability of the module during use.

[0125] In this embodiment, the photovoltaic system can be applied in a photovoltaic power station, such as a ground power station, a rooftop power station, a water surface power station, etc., or can also be applied to devices or apparatuses that use solar energy for power generation, such as a user solar power supply, a solar street lamp, a solar car, a solar building, and so on. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be applied in all fields that require solar power generation. Taking the photovoltaic power generation system network as an example, the photovoltaic system can include a photovoltaic array, a combiner 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 arrays are connected to the combiner box, and the combiner box can collect the current generated by the photovoltaic arrays. The collected current flows through the inverter and is converted into alternating current required by the commercial power grid and then connected to the commercial power grid to achieve solar power supply.

[0126] In the description of this specification, the descriptions with reference to terms such as "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0127] In addition, the above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A back-contact battery component, characterized in that, Comprising: A first battery string and a second battery string, both comprising a plurality of back-contact solar cells connected in series; the first battery string comprises a first solar cell and a second solar cell, the second battery string comprises a third solar cell, and the first solar cell is located between the second solar cell and the third solar cell; A bus bar, at least part of the structure of which is disposed on the second solar cell; An insulating strip that electrically isolates the solder tape connected to the second solar cell from the bus bar; A parallel solder tape that electrically connects the bus bar and electrically connects a plurality of electrical connection structures of the first polarity of the first solar cell and the third solar cell; along the direction from the first solar cell to the third solar cell, the first and last electrical connection structures connected to the first solar cell by the parallel solder tape are a first structure and a second structure respectively, and the first electrical connection structure connected to the third solar cell is a third structure; The parallel solder tape comprises a first section, a second section and a third section, the first section is located on the side of the first structure close to the bus bar, the second section is located between the second structure and the third structure, and the third section is located between the first structure and the second structure; When the back-contact battery assembly is irradiated with AM1.5 light, L1 > L2; Wherein, L1 is the current measured on the first section, and L2 is the current measured on the second section.

2. The back-contact battery assembly according to claim 1, wherein The first battery string comprises a series solder tape that connects the electrical connection structure of the second polarity of the first solar cell and the electrical connection structure of the first polarity of the second solar cell; along the direction from the second solar cell to the first solar cell, the last electrical connection structure connected to the second solar cell by the series solder tape is a fourth structure, and the first electrical connection structure connected to the first solar cell is a fifth structure; L1 = L2 + L3; Wherein, L3 is the current measured on the connection section of the series solder tape, and the connection section is located between the fourth structure and the fifth structure.

3. The back-contact battery assembly according to claim 1, wherein, L1 ≤ 2L2.

4. The back-contact battery assembly according to claim 1, wherein, R1 < R2; Wherein, R1 is the resistance per unit length of the first section, and R2 is the resistance per unit length of the second section.

5. The back-contact battery component according to claim 1, wherein The first battery string comprises a series solder tape that connects the electrical connection structure of the second polarity of the first solar cell and the electrical connection structure of the first polarity of the second solar cell; The resistance per unit length of the first section is less than the resistance per unit length of the series solder tape.

6. The back-contact battery assembly according to claim 5, wherein, The ratio of the resistance per unit length of the first section to the resistance per unit length of the series solder tape is less than or equal to 3 / 4.

7. The back-contact battery assembly according to claim 5, wherein, The cross-sectional area of the first section is larger than the cross-sectional area of the series solder tape.

8. The back-contact battery assembly according to claim 5, characterized in that, The cross-sections of the first section and the series solder tape 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 solder tape.

9. The back-contact battery assembly according to claim 5, wherein, The cross-sections of the first section and the series solder tape 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 solder tape.

10. The back-contact battery assembly according to claim 5, wherein, The cross-sections of the first section and the series solder tape are circular, and the diameter of the cross-section of the first section is greater than the diameter of the cross-section of the series solder tape.

11. The back-contact battery component according to claim 5, characterized in that, The resistivity per unit length of the first segment is less than the resistivity per unit length of the series solder strip.

12. A photovoltaic system, characterized in that, Comprising the back-contact battery assembly according to any one of claims 1-11.

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