Back contact battery assembly and photovoltaic system

Abstract

The invention relates to the technical field of solar cells, and provides a back contact cell assembly and a photovoltaic system.The back contact cell assembly comprises a plurality of cell string units, and back contact cell pieces, covered with insulating strips and bus bars, in cell strings of the cell string units are first cell pieces; and the back contact battery piece which is not covered with the insulating strip and the bus bar is a second battery piece. And the length W of the first battery piece in the first direction meets the following relational expression: W is greater than or equal to W0 + D1 + (1-a%) * (D2-D1). Therefore, on one hand, the insulating strip and the bus bar are arranged on the back surface of the back contact battery piece of the battery string, so that the effective light receiving area of the assembly can be increased, and the attractiveness of the assembly is improved. And on the other hand, the size of the first battery piece covered with the insulating strip and the bus bar is specially designed, and the size of the first battery piece covered with the insulating strip and the bus bar in the first direction is correspondingly increased, so that the double-sided rate of the module can be improved, and the power of the module can be ensured.

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] The back contact battery module is usually composed of a back contact battery cell array, which includes a plurality of back contact battery strings. At present, in the back contact battery module, the edge bus bar is usually arranged at the edge of the battery string and outside the battery string to realize the series connection between the battery strings, and the middle bus bar is arranged in the middle spacing area to realize the parallel connection between the battery strings. However, in such a method, a certain space needs to be reserved at the edge and the middle of the module to place the bus bar, which will reduce the effective light receiving area of ​​the module and also affect the aesthetics of the module.

[0003] In the related art, in order to solve this technical problem, in some solutions, the bus bar is set on the back of the battery cell, and an insulating strip is set between the bus bar and the battery cell. Although this setting method can hide the bus bar, it will cause the bifaciality of the component to decrease, thereby affecting the power of the component. Summary of the invention

[0004] The present application provides a back-contact cell assembly and a photovoltaic system.

[0005] The present application is implemented as follows: the back-contact battery assembly of the embodiment of the present application includes a plurality of battery string units, the battery string unit includes a battery string, an insulating bar and a bus bar, the battery string includes a plurality of back-contact battery sheets connected in series along a first direction, the insulating bar is at least partially arranged on the battery string and extends along a second direction, the second direction intersects with the first direction, the insulating bar covers a partial area of ​​at least one of the back-contact battery sheets in the battery string, the bus bar is arranged on the insulating bar, and the bus bar is arranged on each of the insulating bars;

[0006] In the battery string, the back contact battery sheet covered with the insulating strip and the bus bar is a first battery sheet, and the back contact battery sheet not covered with the insulating strip and the bus bar is a second battery sheet;

[0007] The length W of the first battery cell in the first direction satisfies the following relationship:

[0008] W≥W0+D1+(1-a%)*(D2-D1);

[0009] Wherein, W0 is the length of the second battery cell in the first direction, D1 is the length of the portion of the bus bar located on the first battery cell in the first direction, D2 is the length of the portion of the insulating strip located on the first battery cell in the first direction, and a% is the transmittance of the insulating strip.

[0010] In some embodiments, at least one of the back-contact cells at both ends of the cell string is the first cell, and the insulating strip only covers a portion of the back-contact cell at the end of the cell string.

[0011] In some embodiments, one end of the battery string is a first output end, and the other end is a second output end, the back contact battery cells at both ends of the battery string are the first battery cells, and the two first battery cells are both provided with the insulating strip and the bus bar;

[0012] The bus bar located on one of the first battery slices is electrically connected to the first output end, and the bus bar located on another of the first battery slices is electrically connected to the second output end.

[0013] In some embodiments, in the battery string, the second back-contact battery cell close to one end of the battery string is the first battery cell.

[0014] In some embodiments, in the battery string, the second back contact battery cell near the other end of the battery string is also the first battery cell;

[0015] One end of the battery string is a first output end, and the other end is a second output end. The insulating strip and the bus bar are provided on the two first battery cells. The bus bar on one of the first battery cells is electrically connected to the first output end, and the bus bar on the other first battery cell is electrically connected to the second output end.

[0016] In some embodiments, one end of the battery string is a first output end, and the other end is a second output end, the back contact battery cell located at the other end of the battery string is also the first battery cell, and the two first battery cells are provided with the insulating strip and the bus bar, wherein the bus bar on one of the first battery cells is electrically connected to the first output end, and the bus bar on the other first battery cell is electrically connected to the second output end.

[0017] In some embodiments, two adjacent back-contact battery cells closest to the same end of the battery string are both the first battery cells, and the insulating strip and the bus bar respectively cover partial areas of the two adjacent first battery cells.

[0018] In some embodiments, one end of the battery string is a first output end, and the other end is a second output end, the two adjacent back-contact battery cells closest to one end of the battery string are both the first battery cells, and the two adjacent back-contact battery cells closest to the other end of the battery string are also both the first battery cells;

[0019] The bus bar disposed near one end of the battery string is electrically connected to the first output end, and the bus bar disposed near the other end of the battery string is electrically connected to the second output end.

[0020] In some embodiments, in the battery string, two adjacent back-contact battery sheets are partially stacked.

[0021] In some embodiments, the back contact battery assembly includes at least one series-connected battery cell group, and the series-connected battery cell group includes two battery string units arranged along the second direction;

[0022] In the series-connected battery cell group, the output ends of two battery strings located on the same side have opposite polarities and are connected in series through the bus bar.

[0023] In some embodiments, the back contact battery assembly includes at least one parallel battery cell group, and the parallel battery cell group includes two battery string units arranged along the first direction;

[0024] In the parallel battery cell group, the polarities of the output ends of the two battery strings that are opposite to each other in the first direction are the same; the bus bar is provided at a position close to the other battery string in one of the battery strings, and the bus bar connects the two output ends of the two adjacent battery strings that are opposite to each other in the first direction.

[0025] The present application also provides a photovoltaic system, which includes the back contact cell assembly described in any one of the above items.

[0026] In the back-contact cell assembly and photovoltaic system in the embodiments of the present application, in the cell string, the back-contact cell covered with insulating strips and bus bars is the first cell, and the back-contact cell not covered with insulating strips and bus bars is the second cell. The length W of the first cell in the first direction satisfies the following relationship: W≥W0+D1+(1-a%)*(D2-D1). W0 is the length of the second cell in the first direction, D1 is the length of the portion of the bus bar located on the first cell in the first direction, D2 is the length of the portion of the insulating strip located on the first cell in the first direction, and a% is the light transmittance of the insulating strip. In this way, on the one hand, by arranging the insulating strips and bus bars on the back side of the back-contact cell of the cell string, the effective light receiving area of ​​the assembly can be increased, and the aesthetics of the assembly can be improved. On the other hand, by performing the above-mentioned special design on the size of the first cell covered with insulating strips and bus bars, the size of the first cell covered by the insulating strips and bus bars in the first direction is correspondingly increased, which can improve the double-sidedness of the assembly and ensure the power of the assembly.

[0027] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a module schematic diagram of a photovoltaic system provided in an embodiment of the present application;

[0029] Figure 2 is a schematic structural diagram of a back-contact battery assembly provided in an embodiment of the present application;

[0030] Figure 3 is a schematic structural diagram of a battery string unit of a back-contact battery assembly provided in an embodiment of the present application;

[0031] Figure 4 is a schematic structural diagram of a series-connected battery cell group of a back-contact battery assembly provided in an embodiment of the present application;

[0032] Figure 5 is a schematic structural diagram of a parallel battery cell group of a back-contact battery assembly provided in an embodiment of the present application;

[0033] Figure 6 is another structural schematic diagram of a battery string unit of a back-contact battery assembly provided in an embodiment of the present application;

[0034] Figure 7 is another structural schematic diagram of a battery string unit of a back-contact battery assembly provided in an embodiment of the present application;

[0035] Figure 8 is another structural schematic diagram of a battery string unit of a back-contact battery assembly provided in an embodiment of the present application;

[0036] Fig. 9 This is another structural schematic diagram of the battery string unit of the back-contact battery assembly provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals 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 should not be construed as limiting 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 intended to limit the present application.

[0038] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "lateral", "longitudinal", etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply 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 the present application.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0040] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0042] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed in itself. In addition, the various specific processes and examples of materials provided by the present application, 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.

[0043] See also Figure 1-Figure 2 The photovoltaic system 1000 in the embodiment of the present application may include the back contact battery assembly 200 in the embodiment of the present application, and the back contact battery assembly 200 in the embodiment of the present application may include a plurality of battery string units 100. Figure 3 As shown, the battery string unit 100 may include a battery string 10 , an insulating bar 20 and a bus bar 30 . The battery string 10 includes a plurality of back-contact battery sheets 11 sequentially connected in series along a first direction.

[0044] In each battery string 10, the back contact battery cells 11 in the battery string 10 can be connected in series in sequence along the first direction through positive electrode welding strips and negative electrode welding strips. The number of back contact battery cells 11 in each battery string 10 can be the same. Each battery string 10 has a first output terminal and a second output terminal relative to each other. The first output terminal is the positive electrode welding strip or the negative electrode welding strip on the back contact battery cell 11 at one end of the battery string 10, and the second output terminal is the positive electrode welding strip or the negative electrode welding strip on the back contact battery 11 at the other end of the battery string 10. The polarity of the first output terminal and the second output terminal are opposite, one of which is the positive electrode output terminal and the other is the negative electrode output terminal. It should be pointed out that the way in which the back contact battery cells 11 in the battery string 10 are connected in series through welding strips is a conventional welding strip connection method in the prior art, which will not be described in detail here.

[0045] Specifically, Figure 2As shown, in some embodiments, the back contact battery assembly 200 may include two battery string units 100 arranged along a first direction and a plurality of battery string units 100 arranged along a second direction (eg, Figure 2 The second direction intersects with the first direction, and preferably the first direction is perpendicular to the second direction.

[0046] See also Figure 3 In the battery string unit 100, the insulating strip 20 is at least partially disposed on the battery string 10 and extends along the second direction, and the insulating strip 20 covers a partial area of ​​at least one back contact battery cell 11 in the battery string 10. The bus bar 30 is disposed on the insulating strip 20, and the bus bar 30 is electrically connected to the first output terminal or the second output terminal of the battery string 10. Specifically, each battery string unit 100 includes at least one insulating strip 20 and at least one bus bar 30. The size of each back contact battery cell 11 in the second direction is substantially the same. The bus bar 30 is electrically connected to one of the positive electrode welding strip and the negative electrode welding strip, and is insulated and isolated from the other by the insulating strip 20 to realize the extraction of current.

[0047] Specifically, in the embodiment of the present application, the bus bar 30 may be continuously extended along the second direction or may be discontinuously extended along the second direction. In some examples, the bus bar 30 may be electrically connected to the welding strip of the same polarity by punching holes in the insulating strip 20 (i.e., the insulating strip 20 is continuously extended and punched). In other examples, the insulating strip 20 may be set to an intermittent structure (i.e., the insulating strip 20 is discontinuously extended) to achieve electrical connection between the bus bar 30 and the welding strip of the same polarity and insulation between the bus bar 30 and the welding strip of the opposite polarity.

[0048] like Figure 3 As shown, in the battery string 10, the back contact battery cell 11 covered with the insulating strip 20 and the bus bar 30 is a first battery cell 111, and the back contact battery cell 11 not covered with the insulating strip 20 and the bus bar 30 is a second battery cell 112;

[0049] The length W of the first battery cell 111 in the first direction satisfies the following relationship:

[0050] W≥W0+D1+(1-a%)*(D2-D1);

[0051] Among them, W0 is the length of the second battery cell 112 in the first direction, D1 is the length of the portion of the bus bar 30 located on the first battery cell 111 in the first direction, D2 is the length of the portion of the insulating strip 20 located on the first battery cell 111 in the first direction, and a% is the transmittance of the insulating strip 20.

[0052] In the present application, in order to avoid a large size difference between the first battery cell 111 and the second battery cell 112, it is preferred that W = W0 + D1 + (1-a%) * (D2-D1) 。

[0053] In the back-contact cell assembly 200 and the photovoltaic system 1000 of the embodiment of the present application, on the one hand, by setting the insulating strip 20 and the bus bar 30 on the back side of the back-contact cell 11 of the cell string 10, the effective light receiving area of ​​the assembly can be increased, and the aesthetics of the assembly can be improved. On the other hand, by performing the above-mentioned special design on the size of the first cell 111 covered with the insulating strip 20 and the bus bar 30, the size of the first cell 111 covered by the insulating strip 20 and the bus bar 30 is correspondingly increased in the first direction, so that the bifaciality of the assembly can be increased and the power of the assembly can be guaranteed.

[0054] It is not difficult to understand that in the components of the related art, the size of all battery cells is the same. Since the insulating strip 20 and the bus bar 30 are set on the back of the battery cell, the back will be blocked. Although the purpose of hiding the bus bar 30 is met, it will cause the bifaciality to decrease. Based on this, the inventor of the present application, out of consideration of the bifaciality and efficiency of the component, after repeated research and demonstration, designed the size of the first battery cell 111 covered with the insulating strip 20 and the bus bar 30 based on the size of the second battery cell 112 not covered with the insulating strip 20 and the bus bar 30, the transmittance and width of the insulating strip 20, and the width of the bus bar 30, thereby obtaining the above formula. After research and demonstration by the inventor, it was found that when the size of the first battery cell 110 satisfies the above formula, the bifaciality of the back contact battery assembly 200 can at least be guaranteed to be equivalent to or even higher than the bifaciality in the traditional technical solution.

[0055] In addition, the back contact cell assembly 200 utilizes the photovoltaic effect to receive light and convert light energy into electrical energy. After the bus bar 30 is placed on the back of the back contact cell 11, due to the different light transmittances of the insulating material and the bus bar 30 itself, the different shielding of light will affect the absorption of light by the back of the assembly, thereby affecting the bifaciality of the assembly and reducing the power of the assembly. In the present application, by increasing the area of ​​the shielded back contact cell 11 (i.e., the first cell 111), the current and voltage differences between the cells can be balanced, the bifaciality of the assembly can be increased, and the power of the assembly can be increased.

[0056] Specifically, Figure 2 As shown, in Figure 2 In the example shown, the back-contact battery assembly 200 may include twelve battery string units 100 arranged in six columns in the second direction, each column including two battery string units 100 arranged in the first direction.

[0057] like Figure 2 As shown, in the back contact battery assembly 200, the plurality of bus bars 30 include a plurality of edge bus bars and a plurality of middle bus bars, the edge bus bars are located at the positions of the two ends of the back contact battery assembly 200 in the first direction, and the middle bus bars are located in the middle position of the back contact battery assembly 200, which can be set in the middle position or can be set to one side, and the specific details are not limited here. It is not difficult to understand that in the embodiment of the present application, all the bus bars 30 are located on the back side of the back contact battery sheet 11 to achieve the hiding of the bus bars 30.

[0058] See also Figure 4 In the embodiment of the present application, the back contact battery assembly 200 includes at least one series-connected battery cell group 210, and the series-connected battery cell group 210 includes two battery string units 100 arranged along the second direction. In the series-connected battery cell group 210, the two battery strings 10 are connected in series with each other through a bus bar 30 (i.e., the edge bus bar described above). In the series-connected battery cell group 210, the output terminals of the two battery strings 10 on the same side have opposite polarities. For example, the output terminal on one side of one battery string 10 is a positive output terminal, and the output terminal on the same side of the other battery string 10 is a negative output terminal. The two are electrically connected through the bus bar 30 to realize the series connection of the battery strings 10.

[0059] Specifically, Figure 2 and Figure 4 As shown, two battery string units 100 in the series battery cell group 210 can be provided with two bus bars 30, and the two bus bars 30 located at the edge of the component on the two battery string units 100 are electrically connected. They can be integrally formed or separately formed, and there is no specific limitation here. The two bus bars 30 located in the middle position of the component on the two battery string units 100 are separately arranged, and the polarities of the two bus bars 30 are opposite, and both are electrically connected to the positive and negative poles of the junction box respectively.

[0060] In addition, if Figure 5 As shown, in the back contact battery assembly 200, the back contact battery assembly 200 includes at least one parallel battery cell group 220, and the parallel battery cell group 220 includes two battery string units 100 arranged along the first direction. In the parallel battery cell group 220, the polarities of the output ends of the two battery strings 10 opposite to each other in the first direction are the same, that is, the polarities of the two output ends of the two battery strings 100 opposite to each other at the middle position of the assembly are the same. A bus bar 30 (i.e., the middle bus bar described above) is provided at a position close to another battery string 10 in one of the battery strings 10, and the bus bar 30 electrically connects the two output ends of the two adjacent battery strings 10 opposite to each other in the first direction.

[0061] Specifically, Figure 2 and Figure 5As shown, one of the two battery string units 100 in the parallel battery cell group 220 has two bus bars 30, which are electrically connected to the first output end and the second output end of the battery string 10 respectively, one bus bar 30 is located at the edge of the component, and the other bus bar 30 is located in the middle of the component. The other battery string unit 100 may have only one bus bar 30 and is located at the other edge of the component. In this case, one output end of the battery string 10 of the battery string unit 100 is electrically connected to the bus bar 30 of the previous battery string unit 100 located in the middle of the component, and the polarities of the output ends of the two battery strings 10 electrically connected to the bus bar 30 located in the middle of the component are the same to achieve parallel connection between the two battery strings 10.

[0062] As shown above, in an embodiment of the present application, the back-contact battery cells 11 in the battery string 10 are connected in series through positive electrode welding strips and negative electrode welding strips. In the battery string 10, the first output end and the second output end of the battery string 10 are respectively the positive electrode welding strip and the negative electrode welding strip on the two back-contact battery cells 11 located at the ends of the battery string 10.

[0063] In the battery string 10, the number of back contact battery cells 11 is an even number, and may also be an even number, which is not specifically limited here. The polarity of the first output terminal and the second output terminal are opposite, one is a positive pole and the other is a negative pole. In this case, in the series battery cell group 210, the first output terminal of one battery string 10 and the second output terminal of another battery string 10 are located on the same side and are connected in series through the bus bar 30. In the parallel battery cell group 220, the polarity of the two output terminals of the two battery strings 10 facing each other is the same.

[0064] See also Figure 3 In some embodiments, in the battery string unit 100, at least one of the back contact battery cells 11 located at the two ends of the battery string 10 is a first battery cell 111, and the insulating strip 20 only covers a partial area of ​​the back contact battery cell 11 located at the end of the battery string 10.

[0065] In this way, by setting the insulating strip 20 and the bus bar 30 on the back contact battery sheet 11 at the end of the battery string 10, the bus bar 30 can be hidden by the back contact battery sheet 11 at the end. At the same time, it is only necessary to increase the size of the back contact battery sheet 11 at the end in the first direction accordingly to improve the double-sidedness of the component and facilitate layout. In addition, setting the bus bar 30 on the back contact battery sheet 11 at the end can facilitate welding the bus bar 30 to the output end of the battery string 10 (the positive electrode welding strip or the negative electrode welding strip on the back contact battery sheet 11 at the end).

[0066] For further information, see Figure 3, one end of the battery string 10 is the first output end, and the other end is the second output end, the back contact battery cells 11 at both ends of the battery string 10 are first battery cells 111, and both first battery cells 111 are provided with insulating strips 20 and bus bars 30. Among them, the bus bar 30 located on one of the first battery cells 111 is electrically connected to the first output end, and the bus bar 30 located on the other first battery cell 111 is electrically connected to the second output end.

[0067] In this way, insulating strips 20 and bus bars 30 are provided on the back contact battery cells 11 at both ends of the battery string unit 100, wherein one bus bar 30 can serve as an edge bus bar in the component, and the other bus bar 30 can serve as an intermediate bus bar in the component, thereby hiding both the edge bus bar and the intermediate bus bar. At the same time, it is only necessary to increase the size of the back contact battery cells 11 at both ends of the battery string 10 for easy layout.

[0068] Specifically, Figure 4 As shown, in such an embodiment, in the series-connected battery cell group 210 of the back-contact battery assembly 200, the bus bars 30 of the two battery string units 100 located at the edge of the assembly can be connected in series to realize the series connection of the two battery string units 100. In this case, the bus bars 30 located at the edge of the assembly in the two battery string units 100 of the series-connected battery assembly can be integrally formed, and the insulating strip 20 can also be integrally formed. Of course, in other implementations, the bus bars 30 located at the edge of the assembly in the two battery string units 100 of the series-connected battery assembly can also be two independently formed parts, and then the two bus bars 30 are electrically connected through a conductive member, and the insulating strip 20 can also be integrally formed or separately formed, and there is no specific limitation here.

[0069] In addition, if Figure 5 As shown, in such an embodiment, in the parallel battery cell group 220 of the back-contact battery assembly 200, one of the two battery string units 100 may have two bus bars 30, one located at the edge of the assembly (acting as an edge bus bar) and one located in the middle of the assembly (acting as a middle bus bar), and the other battery string unit 100 has only one bus bar 30, which is located at the edge of the assembly, and the output end of the battery string 10 of the battery string unit 100 facing the battery string 10 of the other battery string unit 100 is electrically connected to the bus bar 30 of the other battery string unit 100 located in the middle of the assembly, thereby realizing the series connection of the two battery strings 10.

[0070] Of course, in some other embodiments, in the parallel battery cell group 220 of the back-contact battery assembly 200, the two battery string units 100 may also each have two bus bars 30, one located at the edge of the assembly (acting as an edge bus bar), and the other located in the middle of the assembly (acting as a middle bus bar). The two bus bars 30 located in the middle of the assembly can be conductively connected to achieve parallel connection of two battery strings 10, and there is no specific limitation here.

[0071] See also Figure 6 In some embodiments, in the battery string 10, the second back contact battery sheet 11 (i.e. Figure 6 and Figure 7 The second back contact cell 11 from top to bottom along the first direction or the second back contact cell 11 from bottom to top along the first direction is the first cell 111. That is, the insulating strip 20 and the bus bar 30 may be disposed on the back contact cell 11 adjacent to the back contact cell 11 at the end of the battery string 10.

[0072] In this way, the insulating strip 20 and the bus bar 30 are arranged on the second back contact battery cell 11 at the edge of the battery string 10. It is only necessary to extend the positive electrode welding strip or the negative electrode welding strip on the back contact battery cell 11 located at the edge to the position of the bus bar 30 for welding to achieve the electrical connection between the bus bar 30 and the output end, without opening holes or discontinuing processing on the insulating strip 20 to avoid displacement of the insulating strip 20.

[0073] Specifically, in such an embodiment, the insulating strip 20 and the bus bar 30 are only located on the second back contact cell 11 closest to the edge of the cell string 10, and the bifaciality can be improved by simply increasing the size of the cell in the first direction.

[0074] See also Figure 7 In some embodiments, in the battery string 10, the second back contact battery cell 11 near the other end of the battery string 10 is also the first battery cell 111, that is, Figure 7 The second back-contact battery cell 11 from top to bottom along the first direction and the second back-contact battery cell 11 from bottom to top along the first direction are both first battery cells 111 .

[0075] One end of the battery string 10 is a first output end, and the other end is a second output end. Insulation strips 20 and bus bars 30 are provided on the two first battery cells 111. The bus bar 30 on one of the first battery cells 111 is electrically connected to the first output end, and the bus bar 30 on the other first battery cell 111 is electrically connected to the second output end.

[0076] As such, in such a case, one of the two bus bars 30 may serve as an edge bus bar in the assembly and the other bus bar 30 may serve as a middle bus bar in the assembly, thereby hiding both the edge bus bar and the middle bus bar.

[0077] Of course, see Figure 6 ,like Figure 6 As shown, in other embodiments, one end of the battery string 10 is the first output end, and the other end is the second output end, and the back contact battery cell 11 at the other end of the battery string 10 is also the first battery cell 111, and the two first battery cells 111 are provided with insulating strips 20 and bus bars 30, wherein the bus bar 30 on one of the first battery cells 111 is electrically connected to the first output end, and the bus bar 30 on the other first battery cell 111 is electrically connected to the second output end. That is to say, in the case where the battery string unit 100 has two bus bars 30, one of the bus bars 30 can be set on the second back contact battery cell 11 near one end of the battery string 10, and the other bus bar 30 can be set on the back contact battery cell 11 at the other end of the battery string 10, and the specific details are not limited here.

[0078] It is not difficult to understand that in such an embodiment, in the back contact battery assembly 200, all bus bars 30 may be located on the second back contact battery sheet 11 closest to the edge of the battery string 10. Similarly, as described above, it is not difficult to understand that in the series battery cell group 210 of the back contact battery assembly 200, the bus bars 30 of the two battery string units 100 located at the edge of the assembly can be connected in series to achieve the series connection of the two battery string units 100. In this case, the bus bars 30 located at the edge of the assembly in the two battery string units 100 of the series battery cell group 210 can be integrally formed, and the insulating strips 20 can also be integrally formed. Of course, in other implementations, the bus bars 30 located at the edge of the assembly in the two battery string units 100 of the series battery cell group 210 can also be two independently formed parts, and then the two bus bars 30 are electrically connected through a conductive member, and the insulating strips 20 can also be integrally formed or separately formed, which is not specifically limited here.

[0079] In addition, in such an embodiment, as described above, in the parallel battery cell group 220 of the back-contact battery assembly 200, one of the two battery string units 100 may have two bus bars 30, one located at the edge of the assembly (acting as an edge bus bar) and one located in the middle of the assembly (acting as a middle bus bar), and the other battery string unit 100 only has one bus bar 30, which is located at the edge of the assembly, and the output end of the battery string 10 of the battery string unit 100 facing the battery string 10 of the other battery string unit 100 is electrically connected to the bus bar 30 of the other battery string unit 100 located in the middle of the assembly, thereby realizing the series connection of the two battery strings 10.

[0080] Of course, in some other embodiments, in the parallel battery cell group 220 of the back-contact battery assembly 200, both battery string units 100 may have two bus bars 30, one located at the edge of the assembly (acting as an edge bus bar), and one located in the middle of the assembly (acting as a middle bus bar). The two bus bars 30 located in the middle of the assembly can be conductively connected to achieve the series connection of the two battery strings 10, and there is no specific limitation here.

[0081] See also Figure 8 In some embodiments, two adjacent back-contact battery cells 11 closest to the same end of the battery string 10 are both first battery cells 111 , and the insulating strip 20 and the bus bar 30 respectively cover partial areas of the two adjacent first battery cells 111 .

[0082] In this way, by arranging the insulating strip 20 and the bus bar 30 between the two back contact battery cells 11 at the edge of the battery string 10, the area of ​​the region covered with the insulating strip 20 and the bus bar 30 on the first battery cell 111 can be reduced, thereby reducing the risk of hidden cracks caused by the insulating strip 20 and the bus bar 30 stacked on the back contact battery cell 11 during the lamination packaging process. At the same time, the bus bar 30 can be fully welded with the welding ribbon and the hiding operation of the bus bar 30 can be more convenient.

[0083] Specifically, in such an embodiment, in the battery string unit 100 , the insulating strip 20 and the bus bar 30 simultaneously cover partial areas of two adjacent back contact battery cells 11 , that is, one insulating strip 20 and one bus bar 30 correspond to two first battery cells 111 .

[0084] In such an embodiment, it is preferred that the portions of the insulating strip 20 and the bus bar 30 located on the two first battery slices 111 have the same length in the first direction, so that the two first battery slices 111 covered by the insulating strip 20 and the bus bar 30 can be battery slices of the same size, thereby reducing the types of battery slices of different sizes. Of course, in some less preferred embodiments, the portions of the insulating strip 20 and the bus bar 30 located on the two first battery slices 111 may also have different lengths in the first direction, in which case, the two first battery slices 111 corresponding to the same insulating strip 20 and the same bus bar 30 have different lengths in the first direction.

[0085] Further, in such an embodiment, one end of the battery string 10 is a first output end, and the other end is a second output end, the two adjacent back-contact battery cells 11 closest to one end of the battery string 10 are both first battery cells 111, and the two adjacent back-contact battery cells 11 closest to the other end of the battery string 10 are also both first battery cells 111. The bus bar 30 disposed near one end of the battery string 10 is electrically connected to the first output end, and the bus bar 30 disposed near the other end of the battery string 10 is electrically connected to the second output end.

[0086] As such, in such a case, one of the two bus bars 30 may serve as an edge bus bar in the assembly and the other bus bar 30 may serve as a middle bus bar in the assembly, thereby hiding both the edge bus bar and the middle bus bar.

[0087] Similarly, as described above, in such an embodiment, in the series-connected battery cell group 210 of the back-contact battery assembly 200, the bus bars 30 of the two battery string units 100 located at the edge of the assembly can be connected in series to achieve the series connection of the two battery string units 100. In this case, the bus bars 30 located at the edge of the assembly in the two battery string units 100 of the series-connected battery cell group 210 can be integrally formed, and the insulating strip 20 can also be integrally formed. Of course, in other implementations, the bus bars 30 located at the edge of the assembly in the two battery string units 100 of the series-connected battery cell group 210 can also be two independently formed parts, and then the two bus bars 30 are electrically connected through a conductive member, and the insulating strip 20 can also be integrally formed or separately formed, and there is no specific limitation here.

[0088] In addition, in such an embodiment, as described above, in the parallel battery cell group 220 of the back-contact battery assembly 200, one of the two battery string units 100 may have two bus bars 30, one located at the edge of the assembly (acting as an edge bus bar) and one located in the middle of the assembly (acting as a middle bus bar), and the other battery string unit 100 only has one bus bar 30, which is located at the edge of the assembly, and the output end of the battery string 10 of the battery string unit 100 facing the battery string 10 of the other battery string unit 100 is electrically connected to the bus bar 30 of the other battery string unit 100 located in the middle of the assembly, thereby realizing the series connection of the two battery strings 10.

[0089] See also Fig. 9 In some embodiments, in the battery string 10 , two adjacent back-contact battery cells 11 are partially stacked.

[0090] In this way, the distance between two adjacent back contact cells 11 in the cell string 10 can be eliminated, thereby reducing light leakage and increasing the power generation per unit area.

[0091] Specifically, in such an embodiment, in the battery string 10, the back contact battery cells 11 may be stacked sequentially along the first direction, that is, the edge of a subsequent battery cell toward the previous battery cell may be stacked on the edge portion of the previous battery cell.

[0092] Of course, it is understandable that in some embodiments, in the battery string 10, only two edges of some back contact battery cells 11 may be stacked, while other back contact battery cells 11 have spacing between them, which is not specifically limited here.

[0093] In some embodiments, in the parallel battery cell group 220, the back contact battery cells 11 in the two battery strings 10 can also be stacked sequentially along the first direction, that is, in the parallel battery cell group 220, the edge of the rear battery cell facing the front battery cell can be stacked on the edge portion of the front battery cell, and it is only necessary for the two opposite output ends of the same polarity of the two battery strings 10 to be electrically connected to the same bus bar 30 (i.e., the middle bus bar) located in the middle of the component.

[0094] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0095] In addition, the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A back contact battery assembly, characterized in that: The invention comprises a plurality of battery string units, wherein the battery string units comprise a battery string, an insulating strip and a bus bar, wherein the battery string comprises a plurality of back-contact battery sheets connected in series along a first direction, wherein the insulating strip is at least partially arranged on the battery string and extends along a second direction, wherein the second direction intersects the first direction, wherein the insulating strip covers a partial area of ​​at least one back-contact battery sheet in the battery string, and wherein the bus bar is arranged on the insulating strip, and wherein each of the insulating strips is provided with the bus bar; In the battery string, the back contact battery sheet covered with the insulating strip and the bus bar is a first battery sheet, and the back contact battery sheet not covered with the insulating strip and the bus bar is a second battery sheet; The length W of the first battery cell in the first direction satisfies the following relationship: W ≥ W0+D1+(1-a%)*(D2-D1); Wherein, W0 is the length of the second battery cell in the first direction, D1 is the length of the portion of the bus bar located on the first battery cell in the first direction, D2 is the length of the portion of the insulating strip located on the first battery cell in the first direction, and a% is the transmittance of the insulating strip.

2. The back contact battery assembly according to claim 1, characterized in that: At least one of the back-contact battery cells located at two ends of the battery string is the first battery cell, and the insulating strip only covers a portion of the back-contact battery cell located at the end of the battery string.

3. The back contact battery assembly according to claim 2, characterized in that: One end of the battery string is a first output end, and the other end is a second output end. The back contact battery cells at both ends of the battery string are the first battery cells, and the two first battery cells are both provided with the insulating strip and the bus bar; The bus bar located on one of the first battery slices is electrically connected to the first output end, and the bus bar located on another of the first battery slices is electrically connected to the second output end.

4. The back contact battery assembly according to claim 1, characterized in that: In the battery string, the second back-contact battery cell close to one end of the battery string is the first battery cell.

5. The back contact battery assembly according to claim 4, characterized in that: In the battery string, the second back contact battery cell close to the other end of the battery string is also the first battery cell; One end of the battery string is a first output end, and the other end is a second output end. The insulating strip and the bus bar are provided on the two first battery cells. The bus bar on one of the first battery cells is electrically connected to the first output end, and the bus bar on the other first battery cell is electrically connected to the second output end.

6. The back contact battery assembly according to claim 4, characterized in that: One end of the battery string is a first output end, and the other end is a second output end. The back-contact battery cell located at the other end of the battery string is also the first battery cell. The insulating strip and the bus bar are provided on two of the first battery cells. The bus bar on one of the first battery cells is electrically connected to the first output end, and the bus bar on the other of the first battery cells is electrically connected to the second output end.

7. The back contact battery assembly according to claim 1, characterized in that: The two adjacent back-contact battery cells closest to the same end of the battery string are both the first battery cells, and the insulating strip and the bus bar respectively cover partial areas of the two adjacent first battery cells.

8. The back contact battery assembly according to claim 7, characterized in that: One end of the battery string is a first output end, and the other end is a second output end, the two adjacent back-contact battery cells closest to one end of the battery string are both the first battery cells, and the two adjacent back-contact battery cells closest to the other end of the battery string are also both the first battery cells; The bus bar disposed near one end of the battery string is connected to the first output end, and the bus bar disposed near the other end of the battery string is electrically connected to the second output end.

9. The back contact battery assembly according to claim 1, characterized in that: In the battery string, two adjacent back-contact battery sheets are partially stacked.

10. The back contact battery assembly according to claim 1, characterized in that: The back contact battery assembly includes at least one battery cell group connected in series, and the battery cell group connected in series includes two battery string units arranged along the second direction; In the series-connected battery cell group, the output ends of two battery strings located on the same side have opposite polarities and are connected in series through the bus bar.

11. The back contact battery assembly according to claim 1, characterized in that: The back contact battery assembly includes at least one parallel battery cell group, and the parallel battery cell group includes two battery string units arranged along the first direction; In the parallel battery cell group, the polarities of the output ends of the two battery strings that are opposite to each other in the first direction are the same; the bus bar is provided at a position close to the other battery string in one of the battery strings, and the bus bar connects the two output ends of the two adjacent battery strings that are opposite to each other in the first direction.

12. A photovoltaic system, characterized in that: A back contact battery assembly comprising any one of claims 1-11.

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