Back contact battery assembly and photovoltaic power generation system

Abstract

The utility model provides a back contact battery assembly and a photovoltaic power generation system. The back contact battery assembly comprises a front plate; the front adhesive film is arranged on the front plate; the at least two battery series sub-assemblies are arranged on the side, away from the front plate, of the front adhesive film, each battery series sub-assembly comprises at least one battery string, each battery string comprises a plurality of battery pieces, each battery piece comprises a first electrode area and a second electrode area which are located on the back face of the corresponding battery piece and are opposite, and the first electrode areas are provided with first welding strips connected with the fine grids; the second electrode area is provided with a second welding strip connected with the fine grid of the other polarity; the battery pieces in one battery series connection sub-assembly are partially overlapped with the battery pieces in another adjacent battery series connection sub-assembly, and the two overlapped battery pieces are connected in parallel through the same first welding strip located on the back sides of the two battery pieces; and the middle bus bar is arranged on the back surface of one of the two overlapped battery pieces, is electrically connected with the first welding strip and is insulated from the second welding strip. Therefore, the edge of the battery piece can be effectively prevented from being crushed during lamination.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to a back-contact battery assembly and a photovoltaic power generation system. Background Art

[0002] Solar cells, also known as photovoltaic cells, are devices that use the photovoltaic effect to directly convert light energy into direct current. The PN junction on the semiconductor in the solar cell can directly convert solar energy into electrical energy through the photovoltaic effect. The most common of these is crystalline silicon solar cells, including monocrystalline silicon solar cells and polycrystalline silicon solar cells. Solar cells are usually in the form of sheets. A solar cell with electrodes of both polarities formed on the back of the cell is a back contact cell.

[0003] In the related art, a plurality of back-contact battery cells are subjected to steps such as string welding, lamination, and packaging to form a back-contact battery assembly. The back-contact battery assembly includes two battery string assemblies arranged at intervals and an intermediate bus bar for connecting the two battery string assemblies in parallel. Since the intermediate bus bar is arranged in the interval area between the two battery string assemblies, the interval area cannot provide good support for the intermediate bus bar, making it easy to crush the battery cells during lamination, resulting in the risk of hidden cracks. In addition, due to the existence of the interval area, the intermediate bus bar can also be seen from the front of the battery assembly, that is, there is a blank space in the middle of the appearance of the battery assembly, which affects the appearance. Utility Model Content

[0004] The embodiments of the present application provide a back-contact cell assembly and a photovoltaic power generation system, which can improve the aesthetics of the back-contact cell assembly while avoiding the risk of hidden cracks in the cell due to lamination.

[0005] In a first aspect, an embodiment of the present application provides a back contact battery assembly, comprising:

[0006] At least two battery series subassemblies, each of which comprises at least one battery string, each of which comprises a plurality of battery cells connected in series, each of which comprises a first electrode region and a second electrode region of opposite polarity located on the back of the battery cell, the first electrode region being provided with a first welding strip connected to a fine grid, and the second electrode region being provided with a second welding strip connected to a fine grid of another polarity; the battery cells in the battery string in one of the battery series subassemblies partially overlap with the battery cells in the battery string in another adjacent battery series subassembly, wherein the two overlapping battery cells are connected in parallel via the same first welding strip, and the first welding strip is located on the back side of the two overlapping battery cells;

[0007] The middle bus bar is arranged on the back side of one of the two battery cells overlapping each other in the two battery series sub-assemblies. The middle bus bar is electrically connected to the first welding strip and is insulated from the second welding strip.

[0008] Optionally, the battery cell is a busbar-less battery cell.

[0009] Optionally, the back-contact battery assembly also includes an intermediate insulating layer, which is located on the side of the first welding strip away from the battery cell, and the intermediate insulating layer forms a first exposed area, and the first exposed area exposes the first welding strip; the intermediate bus bar is arranged on the side of the intermediate insulating layer away from the battery cell, and the intermediate insulating layer insulates the intermediate bus bar from the second welding strip, and the intermediate bus bar is conductively connected to the corresponding exposed first welding strip through the first exposed area.

[0010] Optionally, the intermediate insulating layer covers the first welding strip, and the intermediate insulating layer is provided with a first through hole forming the first exposed area.

[0011] Optionally, the intermediate insulating layer includes a plurality of first intermediate insulating sublayers arranged at intervals, the plurality of first intermediate insulating sublayers cover the first welding strip, and the interval areas between adjacent first intermediate insulating sublayers form the first exposed areas.

[0012] Optionally, the intermediate busbar includes a first conductive body, the intermediate insulating layer includes a plurality of second intermediate insulating sublayers spaced apart from each other, the second intermediate insulating sublayers are formed on the surface of the first conductive body, and the interval areas between adjacent second intermediate insulating sublayers form the first exposed area.

[0013] Optionally, the thickness of the intermediate insulating layer is between 0.05 mm and 0.8 mm.

[0014] Optionally, the width of the intermediate insulating layer is greater than or equal to the width of the intermediate bus bar.

[0015] Optionally, along the series connection direction of the battery cells in the battery string, the intermediate bus bar is located in the middle of one of the two battery cells that overlap with each other in two battery series connection sub-assemblies.

[0016] Optionally, a plurality of the battery cells in each of the battery strings are partially overlapped to form the battery string, and contact regions between the overlaps are not conductively connected.

[0017] Optionally, the overlapping areas of adjacent battery cells in the battery string are provided with series welding strips to fixedly connect the adjacent battery cells, and the series welding strips connect the adjacent battery cells in series, wherein the series welding strips are located on the back side of the adjacent battery cells.

[0018] Optionally, each of the battery series subassemblies includes at least two battery strings, the battery strings in the battery series subassembly are arranged side by side, and two adjacent battery strings in the battery series subassembly are connected in series via a first bus bar, which is arranged on the back of the battery cell.

[0019] Optionally, the intermediate bus bars include at least two, and the two intermediate bus bars include lead-out ends disposed adjacent to each other, and the lead-out ends are used to be connected to a junction box via lead-out wires; wherein the adjacent intermediate bus bars have different polarities.

[0020] Optionally, the two intermediate bus bars are staggered or collinear with each other in the extension direction of the intermediate bus bar, and the spacing between the two lead wires of adjacent lead-out end portions is equal to the spacing between the welding terminals in the junction box.

[0021] Optionally, along the series connection direction of the battery cells in the battery string, the first bus bar is located in the middle of the battery cells at the end positions in the battery string.

[0022] Optionally, two adjacent battery strings in each battery series-connected subassembly partially overlap.

[0023] In a second aspect, an embodiment of the present application further provides a photovoltaic power generation system, comprising a back-contact cell assembly as described in any of the above items.

[0024] The embodiment of the present application provides a back-contact battery assembly and a photovoltaic power generation system, by partially overlapping the battery cells in the battery string in the battery series subassembly with the battery cells in the battery string in another adjacent battery series subassembly, and the two overlapping battery cells are connected in parallel through the same first welding strip, so that the first welding strip can not only be electrically connected to the middle bus bar set on the back of the battery cell, but also play the role of fixing the two battery cells. Furthermore, there is no gap between the overlapping battery cells, which can well hide the first welding strip, and is suitable for making full-screen components. Moreover, this structure can set the middle bus bar on the back of one of the two overlapping battery cells of the two battery series subassemblies, such as being set in the approximate middle of the battery cell, away from the fragile edge part, so that the risk of the edge of the battery cell being crushed and the battery cell being cracked during lamination can be effectively avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0026] In order to more completely understand the present application and its beneficial effects, the following description will be given in conjunction with the accompanying drawings, wherein the same figure numbers represent the same parts in the following description.

[0027] Figure 1 A schematic diagram of the structure of a back-contact battery assembly provided in an embodiment of the present application.

[0028] Figure 2 for Figure 1 A magnified schematic diagram of center A.

[0029] Figure 3 for Figure 1 A first partial schematic diagram of the middle bus bar being arranged at the battery string position.

[0030] Figure 4 for Figure 3 Enlarged schematic diagram of point D in the middle.

[0031] Figure 5 for Figure 4 A cross-sectional view at the first exposed area.

[0032] Figure 6 It is a partial structural diagram of the welding strip, insulating layer and bus bar in the related technology.

[0033] Figure 7 A second partial schematic diagram of an intermediate bus bar provided in an embodiment of the present application being arranged at a battery string position.

[0034] Figure 8 A schematic diagram of the connection between the intermediate bus bar and the welding strip provided in an embodiment of the present application.

[0035] Fig. 9 for Figure 1 Enlarged schematic diagram of point C in the middle.

[0036] Fig.10 This is a partial schematic diagram of two adjacent intermediate bus bars provided in an embodiment of the present application when they are collinear.

[0037] Fig.11 for Figure 1 A magnified schematic diagram of point B in the middle.

[0038] Fig.12 A first partial schematic diagram of a first bus bar provided in an embodiment of the present application being arranged at a battery string position.

[0039] Fig.13 for Fig.12 Enlarged schematic diagram of point H in the middle.

[0040] Fig.14 A schematic diagram of the structure when the lead wire provided in an embodiment of the present application is connected to the middle bus bar.

[0041] Reference numerals:

[0042] 100. Back contact battery assembly;

[0043] 10. Battery series subassembly; 11. Battery string; 111. Battery cell; 11a. First electrode region; 11b. Second electrode region;

[0044] 20. first insulating layer; 21. second exposed area;

[0045] 30. First bus bar;

[0046] 41. First welding strip; 42. Second welding strip; 43. Series welding strip; 44. Third welding strip; 45. Fourth welding strip;

[0047] 50, middle insulating layer; 51, first exposed area; 511, first through hole; 52, first middle insulating sublayer; 53, second middle insulating sublayer;

[0048] 60. middle bus bar; 61. first conductive body; 62. lead end; 70. lead wire; 81. backing film; 82. back plate; 83. opening area. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0050] Reference to "embodiment" or "implementation" herein means that a particular feature, component, or characteristic described in conjunction with the embodiment or implementation may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0051] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are 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 therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0052] 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.

[0053] 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.

[0054] The disclosure below provides a plurality of 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 merely examples, and the purpose is not 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 various specific examples of processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use scenarios of other materials.

[0055] It should be noted that in the related art, a plurality of back-contact battery cells are subjected to steps such as string welding, lamination, and packaging to form a back-contact battery assembly. Among them, the back-contact battery assembly includes two battery string assemblies arranged at intervals and an intermediate bus bar for connecting the two battery string assemblies in parallel. Since the intermediate bus bar is arranged in the interval area between the two battery string assemblies, the interval area cannot provide good support for the intermediate bus bar, making it easy to crush the battery cells during lamination, resulting in the risk of hidden cracks. In addition, due to the existence of the interval area, the intermediate bus bar can also be seen from the front of the battery assembly, that is, there is a blank in the middle of the appearance of the battery assembly, which affects the appearance.

[0056] The embodiments of the present application provide a back-contact battery assembly and a photovoltaic power generation system, which can improve the aesthetics of the back-contact battery assembly while avoiding the risk of hidden cracks in the battery cells caused by lamination. Specifically, by partially overlapping the battery cells in the battery string in the battery series subassembly with the battery cells in the battery string in another adjacent battery series subassembly, the two overlapping battery cells are connected in parallel through the same first welding strip, so that the first welding strip can not only be electrically connected to the middle bus bar set on the back of the battery cell, but also play a role in fixing the two battery cells. Furthermore, there is no gap between the overlapping battery cells, which can well hide the first welding strip, and is suitable for making full-screen components. Moreover, with this structure, the middle bus bar can be set on the back of one of the two overlapping battery cells of the two battery series subassemblies, such as being set in the approximate middle of the battery cell, away from the fragile edge part, so that the risk of hidden cracks in the battery cell caused by the edge of the battery cell being crushed during lamination can be effectively avoided.

[0057] Based on this, see Figures 1 to 3 An embodiment of the present application provides a back-contact battery assembly, including a front plate, a front adhesive film, an intermediate bus bar 60 and at least two battery series sub-assemblies 10, wherein the front adhesive film is arranged on the front plate, and the battery series sub-assemblies 10 are arranged on the side of the front adhesive film away from the front plate.

[0058] Among them, each battery series subassembly 10 includes at least one group of battery strings 11, and each battery string 11 includes a plurality of battery cells 111 connected in series. It can be understood that the battery cell 111 can be made of semiconductor materials, such as P-type silicon wafers, which form PN junctions after phosphorus diffusion. Among them, after the semiconductor structure absorbs solar energy, it excites and generates electron-hole pairs. The electron-hole pairs are separated by the self-built electric field of the PN junction inside the semiconductor. The electrons flow into the N region and the holes flow into the P region, thereby forming a photogenerated electric field. Generally speaking, the battery cell 111 is a sheet structure. The side that can absorb light energy and convert it into electrical energy is called the light-absorbing side or the front side, and the other side is called the back side. The solar cell with electrodes of both polarities formed on the back of the battery is a back-contact battery. In the embodiment of the present application, when the battery cell 111 is installed for normal use, the side facing upward is called the front side, and the other side opposite to the front side is called the back side. Each cell 111 includes a first electrode region 11a and a second electrode region 11b of opposite polarity located on the back of the cell 111. The first electrode region 11a is provided with a first welding strip 41 connected to the fine grid, and the second electrode region 11b is provided with a second welding strip 42 connected to the fine grid of the other polarity. In this way, the current of the fine grid can be conducted by the welding strip. It can be understood that, as Figure 1 and Figure 2 As shown, it is a back view of the battery string 11, which includes a first electrode region 11a and a second electrode region 11b arranged alternately, such as, including a plurality of positive electrode regions and negative electrode regions arranged alternately. Each positive electrode region and negative electrode region are substantially parallel to the edge of the battery cell 111 and are arranged alternately, and each battery cell 111 is substantially rectangular, wherein the substantially rectangular battery cell 111 can be, for example, a square, or another rectangle, and can have a standard corner, a cut corner or a rounded corner, which is specifically set according to actual production needs, and is not specifically limited here. At the same time, the number of its positive electrode region and negative electrode region is determined according to the actual size of the battery cell, the width and distance of the positive electrode fine grid line and the negative electrode fine grid line, and is not specifically limited here. Among them, the fine grid line can be set on the back of the battery cell 111 by screen printing, and the welding strip can be set in the positive electrode region and the negative electrode region by lamination welding, so as to form an electrical connection with the fine grid, and play a role in guiding the current. It can also be understood that in the battery string 11, the battery string 11 may include two battery cells 111 connected in series, three battery cells 111 connected in series, or any other greater number of battery cells 111. The specific number of battery cells 111 to be connected in series can be determined based on actual usage.

[0059] Please continue reading Figure 2 and Figure 3In the embodiment of the present application, the battery cell 111a in the battery string 11 in one battery series subassembly 10 partially overlaps with the battery cell 111a in the battery string 11 in another adjacent battery series subassembly 10, wherein the two overlapping battery cells 111a are connected in parallel through the same first welding strip 41, and the first welding strip 41 is located on the back side of the two overlapping battery cells 111a. In this way, it is convenient to weld the first welding strip 41 to the battery cell 111a, and it can effectively prevent the risk of hidden cracking of the battery skin during lamination, and it can also play the role of fixing the two adjacent battery cells 111a together. For example, in the two overlapping battery cells 111, one section of the same first welding strip 41 is welded to the first electrode region 11a of one of the battery cells 111a, and the other section is welded to the first electrode region 11a of the other battery cell 111a. The middle bus bar 60 is arranged on the back of one of the two overlapping battery cells 111a of the two battery series sub-assemblies 10, and the middle bus bar 60 is electrically connected to the first welding strip 41, and is insulated from the second welding strip 42. In this way, by partially overlapping the battery cell 111a in the battery string 11 in the battery series sub-assembly 10 with the battery cell 111a in the battery string 11 in another adjacent battery series sub-assembly 10, the two overlapping battery cells 111a are connected in parallel through the same first welding strip 41, so that the first welding strip 41 can not only be electrically connected to the middle bus bar 60 arranged on the back of the battery cell 111, but also play a role in fixing the two battery cells 111a. It can be understood that the overlapping area of ​​the battery cells is not conductively connected, or in other words, the overlapping area does not need to be provided with a connecting layer such as a conductive glue or other adhesive glue, and the battery cells only need to overlap, or in other words, the two only need to be in contact, and the two overlapping battery cells 111a are fixed and connected in parallel through the same first welding strip 41. Furthermore, there is no gap between the overlapping battery cells 111a, which can well hide the first welding strip 41, and is suitable for making full-screen components. Moreover, with this structure, the intermediate bus bar 60 can be set on the back of one of the two battery cells 111a that overlap each other in the two battery series sub-components 10, such as being set at a position roughly in the middle of the battery cell 111a, away from the fragile edge parts, so that the risk of the edge of the battery cell 111a being crushed during lamination and the battery cell 111a being cracked can be effectively avoided. Furthermore, with this structure, the intermediate bus bar 60 can be set at any position on the back of one of the two battery cells 111a that overlap each other in the two battery series sub-components 10, and the operability is also stronger.

[0060] It can be understood that the partial overlapping arrangement of the battery cell 111a in the battery string 11 in the battery series subassembly 10 and the battery cell 111a in the battery string 11 in another adjacent battery series subassembly 10 means that the battery cell 111a in the battery string 11 in the battery series subassembly 10 overlaps a portion of the area with the battery cell 111a in the battery string 11 in another adjacent battery series subassembly 10. Wherein, illustratively, the overlapping width range can be 0 mm to 0.5 mm, such as, the overlapping width range can be 0 mm, 0.1 mm, 0.2 mm, 0.4 mm or 0.5 mm, and the present application is not limited thereto.

[0061] It should be noted that in order to hide the busbar, it is placed on the back of the battery in the related art. In order to prevent the battery from short-circuiting, an insulating layer is usually covered on the battery to insulate the busbar from the battery as a whole. Although this method can prevent the busbar from short-circuiting the battery, it will make the current collection effect poor.

[0062] Based on this, in some embodiments, please refer to Figures 3 to 5 In order to better realize the electrical connection between the middle bus bar 60 and the first welding strip 41 and the insulation between the middle bus bar 60 and the second welding strip 42, the back contact battery assembly 100 may further include an intermediate insulating layer 50, which is located on the side of the first welding strip 41 away from the battery cell 111a, and the middle insulating layer 50 is formed with a first exposed area 51, and the first exposed area 51 exposes the first welding strip 41. Among them, the middle bus bar 60 is arranged on the side of the middle insulating layer 50 away from the battery cell 111a, and the middle insulating layer 50 insulates the middle bus bar 60 from the second welding strip 42, and the middle bus bar 60 is conductively connected to the corresponding exposed first welding strip 41 through the first exposed area 51. Thus, with the perspective when the back side of the battery cell 111a is facing upward as a reference, the middle bus bar 60 is located on the top layer of the first welding strip 41, or the first welding strip 41 is located on the side of the middle bus bar 60 facing the battery cell 111a. Thus, even if the middle insulating layer 50 is provided, the first welding strip 41 can be completely attached to the electrode area, that is, it can ensure that the first welding strip 41 is connected to a sufficient number of fine grids, making full use of each fine grid on the battery cell 111a, better collecting current, and improving the effect of collecting current. It can be understood that this structure of the back contact battery assembly 100 can effectively improve the effect of current collection while hiding the middle bus bar 60.

[0063] In particular, the above structure of the present application is more suitable for a battery cell without a main grid. It can be understood that a battery cell without a main grid refers to a battery cell 111 in which a fine grid is provided but no main grid is provided, and a welding strip is directly provided on the electrode area of ​​the original main grid, and the current on the fine grid is directly derived through the electrical connection between the welding strip and the fine grid. In this way, the more the welding strip is attached to the battery cell 111, the more fine grids it can be connected to, thereby deriving more current. The less the welding strip is attached to the battery cell 111, the less the part that can be connected to the fine grid, thereby deriving less current. For your understanding, please refer to Figure 6 If the welding strip 40c is set on the side of the middle bus bar 30c away from the battery cell 111c, that is, with the perspective when the back of the battery cell 111c is facing upward as a reference, the welding strip 40c is set on the top layer of the middle bus bar 30c. At this time, a part of the welding strip 40c will be blocked by the middle bus bar 30c and the middle insulating layer 20c, so that the welding strip 40c cannot be completely attached to the battery cell 111c. In this way, some fine grids on the battery cell 111c cannot be connected to the welding strip 40c, and the current of some fine grids is lost. In the present application, by setting the specific positions of the first welding strip 41, the intermediate insulating layer 50 and the intermediate bus bar 60, and setting the specific structure of the intermediate insulating layer 50, that is, by setting the intermediate insulating layer 50 on the side of the first welding strip 41 away from the battery cell 111a, the intermediate insulating layer 50 is formed with a first exposed area 51, and the first exposed area 51 exposes the first welding strip 41 of the first electrode area 11a, and the intermediate bus bar 60 is set on the side of the intermediate insulating layer 50 away from the battery cell 111, and the intermediate insulating layer 50 insulates the intermediate bus bar 60 from the second welding strip 42 of the second electrode area 11b, and the intermediate bus bar 60 is conductively connected to the first exposed welding strip 41 corresponding to the first exposed area 51. Specifically, taking the viewing angle when the back of the battery cell 111a is facing upward as a reference, please refer to Figure 5 The middle bus bar 60 is located on the top layer of the first welding strip 41, or the first welding strip 41 is located on the side of the middle bus bar 60 facing the battery cell 111a. In this way, even if the middle insulating layer 50 is provided, the first welding strip 41 can be completely attached to the electrode area, that is, it can be ensured that the first welding strip 41 is connected to enough fine grids, making full use of each fine grid of the battery cell 111a, better collecting current, and improving the effect of collecting current.

[0064] In some embodiments, in order to better connect the first welding ribbon 41 to the middle bus bar 60 and not prevent the first welding ribbon 41 from being completely attached to the electrode area of ​​the battery cell 111, as shown in FIG. Figure 4 and Figure 5As shown, the middle insulating layer 50 covers the first welding strip 41 and the second welding strip 42, and the middle insulating layer 50 is provided with a first through hole 511 forming the first exposed area 51. That is, the first through hole 511 penetrating along the thickness direction of the middle insulating layer 50 forms the first exposed area 51. Among them, the intermediate insulating layer 50 covers the first welding strip 41 of the first electrode area 11a and the second welding strip 42 of the second electrode area 11b, and because the intermediate insulating layer 50 has a first through hole 511, the first through hole 511 can expose the first welding strip 41 of the first electrode area 11a, so that the intermediate bus bar 60 can be connected to the first welding strip 41 at the first through hole 511, and the intermediate insulating layer 50 can prevent the intermediate bus bar 60 from short-circuiting the battery cell 111. In addition, due to the existence of the first through hole 511, the intermediate insulating layer 50 will not hinder the conductive connection between the intermediate bus bar 60 and the first welding strip 41, and it is also convenient to completely attach the first welding strip 41 to the battery cell 111a, so that the first welding strip 41 can be connected to more fine grids.

[0065] Exemplarily, the middle insulating layer 50 can be an insulating adhesive, or a non-conductive tape or insulating film, such as a PET or PI tape with acrylic acid or silicone, or a PET or PI substrate coated with ethylene-vinyl acetate copolymer or hot melt adhesive on one or both sides. It can be understood that the middle insulating layer 50 can include materials such as ethylene-vinyl acetate copolymer, resin material, polyimide or polypropylene or polyethylene, and can also include an acrylic adhesive layer.

[0066] It should be noted that the thickness of the intermediate insulating layer 50 cannot be made too thick or too thin. If the intermediate insulating layer 50 is too thin, it is not convenient to operate during pasting, it is easy to deform when pulled, and there is a risk of damage to long-term insulation. If it is too thick, the height difference will increase, and the stress generated during the lamination process is large, which is easy to cause fragments and increase the risk of cold soldering. Based on this, in the embodiment of the present application, the thickness of the intermediate insulating layer 50 can be set between 0.05 mm and 0.8 mm. In this way, the intermediate insulating layer 50 will not be too thin or too thick. For example, the thickness of the intermediate insulating layer 50 can be 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm or 0.8 mm.

[0067] The width of the intermediate insulating layer 50 is greater than or equal to the width of the intermediate bus bar 60. If the width of the intermediate insulating layer 50 is too narrow, the intermediate bus bar 60 will be exposed, and there is a risk of the intermediate bus bar 60 contacting with the opposite electrode area or the opposite welding strip and causing a short circuit.

[0068] Alternatively, in some embodiments, in order not to prevent the first welding ribbon 41 from being completely attached to the electrode area of ​​the battery cell 111, please refer to Figure 7The middle insulating layer 50 includes a plurality of first middle insulating sublayers 52 arranged at intervals, and the plurality of first middle insulating sublayers 52 cover the second welding strips 42, and the intervals between adjacent first middle insulating sublayers 52 form first exposed areas 51. In this way, the first middle insulating sublayers 52 only cover the second welding strips 42 that need to be insulated, and the first welding strips 41 welded to the middle bus bar 60 can be completely attached to the electrode area corresponding to the battery cell 111a due to the existence of the first exposed area 51, so that the first welding strips 41 can be connected to more fine grids.

[0069] Exemplarily, the first intermediate insulating sublayer 52 can be an insulating adhesive, or it can be a non-conductive tape or insulating film, such as, it can be a PET or PI tape with acrylic acid or silicone, or a PET or PI substrate with ethylene-vinyl acetate copolymer or hot melt adhesive coated on one side or both sides. It can be understood that the first intermediate insulating sublayer 52 can include materials such as ethylene-vinyl acetate copolymer, resin material, polyimide or polypropylene or polyethylene, and can also include an acrylic adhesive layer.

[0070] Alternatively, in some other embodiments, in order not to prevent the first welding strip 41 from being completely attached to the electrode area of ​​the battery cell 111, please refer to Figure 8 , the middle bus bar 60 includes a first conductive body 61, the middle insulating layer 50 includes a plurality of second middle insulating sublayers 53 arranged at intervals, the second middle insulating sublayers 53 are formed on the surface of the first conductive body 61, and the interval area between adjacent second middle insulating sublayers 53 forms a first exposed area 51. In this way, the first welding strip 41 can be welded to the middle bus bar 60 at the first exposed area 51, and since the first conductive body 61 of the middle bus bar 60 is covered by the second middle insulating sublayer 53 except for the first exposed area 51, when the middle bus bar 60 is arranged on the battery cell 111, the second middle insulating sublayer 53 can prevent the middle bus bar 60 from being electrically connected to the second welding strip 42 that needs to be insulated. The existence of the first exposed area 51 can make the first welding strip 41 welded to the middle bus bar 60 completely fit on the electrode area corresponding to the battery cell 111a, so that the first welding strip 41 can be connected to more fine grids.

[0071] Exemplarily, the second intermediate insulating sublayer 53 may be an insulating adhesive, or may be a non-conductive tape or insulating film, such as a PET or PI tape with acrylic acid or silicone, or a PET or PI substrate coated with ethylene-vinyl acetate copolymer or hot melt adhesive on one or both sides. It is understood that the second insulating sublayer may include ethylene-vinyl acetate copolymer, resin material, polyimide or polypropylene or polyethylene and other materials, and may also include an acrylic adhesive layer. Of course, the second intermediate insulating sublayer 53 may also be an insulating coating directly coated on the first conductive body 61, and the thickness of the insulating coating may be between 5 microns and 150 microns, which is not limited in this application. It is understood that by setting the above structure, the intermediate bus bar 60 can be hidden on the back of the back contact battery assembly 100, so that the appearance color of the front of the assembly can be consistent, such as achieving a full black effect, which is conducive to the full black design of the back contact battery assembly 100, or achieving a full screen effect, that is, there is no gap between each battery cell due to overlap.

[0072] Among them, in the back contact battery assembly 100, the middle insulating layer 50 can be black, so that the middle bus bar 60 can be better hidden. The middle insulating layer 50 can also be white, so that the reflected light from the back of the battery cell 111 to the front of the battery cell 111 can be increased, and the light can be fully utilized. Of course, the middle insulating layer 50 can also be transparent, so this application does not limit it here.

[0073] Preferably, along the series connection direction of the battery cells 111 in the battery string 11 (such as the second direction H2), the middle bus bar 60 is located in the middle of one of the two battery cells 111a that overlap each other in the two battery series subassemblies 10, so that the middle bus bar 60 can be away from the fragile edge of the battery cell 111a, so that the risk of the battery cell 111a being crushed and cracked can be effectively avoided during lamination. Such a setting can also effectively shorten the transmission distance of the current and reduce the transmission loss of the first welding strip 41.

[0074] In some embodiments, as shown in the figure, each battery series subassembly 10 includes at least two battery strings 11, and the battery strings 11 in the battery series subassembly 10 are arranged side by side. Two adjacent battery strings 11 in the battery series subassembly 10 are connected in series through the first bus bar 30, and the first bus bar 30 is arranged on the back of the battery cell 111. Specifically, the first bus bar 30 is arranged on the back of the battery cell 111 at the end of the battery string 11. It can be understood that the first bus bar 30 is arranged on the back of the battery cell 111, which is more conducive to forming a full-screen component. In addition, the middle bus bar 60 is also arranged on the back of the battery cell 111, so that all bus bars can be hidden, further reducing the area of ​​the non-battery cell 111 area and increasing the proportion of the effective screen (battery cell 111 area). Under the condition of ensuring that the size of the component remains unchanged and meeting the electrical structure design, a larger area of ​​battery cells 111 can be accommodated for power generation, thereby increasing the component power and component conversion efficiency, and reducing the unit watt cost.

[0075] Among them, two adjacent battery strings in each battery series subassembly partially overlap. That is, in the extension direction of the first bus bar 30 (such as the first direction H1), two adjacent battery strings 11 can partially overlap. In this way, the first bus bar 30 can be better hidden. It is more conducive to the production of full-screen components. Of course, in some other embodiments, in the extension direction of the first bus bar 30, if two adjacent battery strings 11 are spaced apart, a first insulating layer 20 can be set in the spacing area to shield the first bus bar 30 at the spacing area.

[0076] In the embodiment of the present application, the first bus bar 30 and the middle bus bar 60 can be conventional bus bars or bus bars with special processing structures, such as bus bars with hollow, perforated, woven structures, etc. It can be understood that the special processing structure can effectively reduce the risk of poor solder joints caused by thermal stress deformation caused by temperature changes in welding, lamination, etc.

[0077] Since the specific number of battery series sub-assemblies is not limited in this application, the number of the intermediate bus bars 60 can also be specifically set according to actual conditions. For example, Fig. 9 As shown, the intermediate busbars 60 include at least two, and the two intermediate busbars 60 include adjacent lead-out ends 62, which are used to connect to the junction box through lead-out wires 70; wherein adjacent intermediate busbars 60 have different polarities.

[0078] See also Fig. 9 , the two middle bus bars 60 are staggered with each other in the extending direction of the middle bus bars 60. Fig.10, the two middle bus bars 60 are collinear in the extension direction of the middle bus bar 60. The spacing L1 between the two lead wires 70 of the adjacent lead end portions 62 is equal to the spacing between the welding terminals in the junction box. In this way, the welding terminals in the junction box can be better matched without redesigning the junction box.

[0079] It is understandable that the width of the intermediate insulating layer 50 below the lead-out end portion 62 is at least greater than the width of the intermediate bus bar 60 to prevent the intermediate bus bar 60 from contacting with anisotropic welding strips or anisotropic electrode regions to cause a short circuit.

[0080] Exemplarily, each battery series subassembly 10 includes two battery strings 11 connected in series by a first bus bar 30. The number of the intermediate bus bars 60 can be set according to actual conditions, for example, the number of the intermediate bus bars 60 can be set to four, and two adjacent intermediate bus bars 60 are connected to one junction box, so that four intermediate bus bars can be connected to three junction boxes.

[0081] In order to more clearly explain the specific structure of the battery string in the battery series sub-assembly, please refer to Figure 1 In the battery series subassembly 10, each battery string 11 includes a plurality of battery cells 111 connected in series, wherein Fig.11 , multiple battery cells 111 are partially overlapped to form a battery string 11, and the contact areas between the overlaps are not conductively connected, that is, no conductive glue or other adhesive is required between the overlapped areas, and the battery cells are simply overlapped together. Among them, the overlapping areas of adjacent battery cells 111 in the battery string 11 are provided with series welding strips 43 to fix the adjacent battery cells 111, and the series welding strips 43 connect the adjacent battery cells 111 in series, wherein the series welding strips 43 are located on the back side of the adjacent battery cells 111. In this way, there is no gap between the battery cells 111 and the battery cells 111, so that the series welding strips 43 can be better hidden, and the overlapping arrangement between the battery cells 111 can reduce the size of the battery string 11, thereby making the occupied space of the battery string 11 smaller. In other words, when the size of the battery string 11 is constant, more battery cells 111 can be placed to increase the power of the battery string 11 and reduce the cost per watt. Furthermore, the series welding strip 43 not only connects the battery cells 111 in series, but also fixes two adjacent battery cells 111 . This is a one-piece multi-purpose device, which reduces the number of steps required to make the battery string 11 and saves materials.

[0082] Furthermore, since the battery cells 111 in the battery string 11 overlap with each other, that is, there is no gap between the battery cells 111, there is no need to set a shielding insulating layer in the gap between the battery cells 111 to hide the series welding strips 43, thereby reducing the use of shielding insulating layers, reducing production costs, and making rework easier.

[0083] It can be understood that the partial overlapping arrangement of multiple battery cells 111 in the battery string 11 means that adjacent battery cells 111 in the battery string 11 overlap a portion of the area. Exemplarily, the overlapping width range may be 0 mm to 0.5 mm, such as 0 mm, 0.1 mm, 0.2 mm, 0.4 mm or 0.5 mm, and the present application does not limit this.

[0084] It should also be noted that in the battery series subassembly 10, two adjacent battery strings 11 are connected in series through the first bus bar 30, and the first bus bar 30 is arranged on the back of the battery cell 111. Specifically, the first bus bar 30 is arranged on the back of the battery cell 111 located at the end of the battery string 11. Preferably, along the series connection direction of the battery cells 111 in the battery string 11, the first insulating layer 20 and the first bus bar 30 are located in the middle of the battery cell 111 at the end position in the battery string 11. In this way, the transmission distance of the current can be effectively shortened, and the risk of transmission loss of the welding strip and edge cracking can be reduced.

[0085] For example, the thickness of the first bus bar 30 can be between 0.06 mm and 0.3 mm, and the width can be between 8 mm and 20 mm, so as to reduce the risk of hidden cracks in the battery cells after lamination. The material of the first bus bar 30 can be a tinned copper bus bar, a conductive copper foil, or an aluminum-based copper strip.

[0086] Among them, the specific setting principle of the first bus bar 30 and the first insulating layer 20 is roughly the same as the specific setting principle of the intermediate bus bar 60 and the intermediate insulating layer 50. In order to more clearly illustrate the specific setting of the first bus bar 30 and the first insulating layer 20, this will be explained in conjunction with the accompanying drawings below.

[0087] See also Fig.12 and Fig.13The back of the battery cell 111 at the end of the battery string 11 has a first electrode region 11a and a second electrode region 11b of different polarity, wherein the first electrode region 11a is provided with a third welding strip 44, and the second electrode region 11b is provided with a fourth welding strip 45, and the first insulating layer 20 is provided on the side of the third welding strip 44 and the fourth welding strip 45 away from the battery cell 111, and the first insulating layer 20 forms a second exposed area 21, and the second exposed area 21 exposes the fourth welding strip 45 of the second electrode region 11b. Among them, the first bus bar 30 is provided on the side of the first insulating layer 20 away from the battery cell 111, and the first insulating layer 20 insulates the first bus bar 30 from the third welding strip 44 of the first electrode region 11a, and the first bus bar 30 is conductively connected to the fourth welding strip 45 exposed corresponding to the second exposed area 21. Thus, with the perspective when the back of the battery cell 111 is facing upward as a reference, the first bus bar 30 is located on the top layer of the fourth welding strip 45, or the fourth welding strip 45 is located on the side of the first bus bar 30 facing the battery cell 111. Thus, even if the first insulating layer 20 is provided, the fourth welding strip 45 can be completely attached to the electrode area, that is, it can ensure that the fourth welding strip 45 is connected to a sufficient number of fine grids, making full use of each fine grid on the battery cell 111, better collecting current, and improving the effect of collecting current. It can be understood that this structure of the back contact battery assembly 100 can effectively improve the effect of current collection while hiding the first bus bar 30.

[0088] It can be understood that the specific embodiments of the first insulating layer 20 forming the second exposed area 21 can refer to the various embodiments of the intermediate insulating layer 50 forming the first exposed area 51, which will not be elaborated in this application.

[0089] In the back contact battery assembly 100, the first insulating layer 20 can be black, so that the first bus bar 30 can be better hidden. The first insulating layer 20 can also be white, so that the reflected light from the back of the battery cell 111 to the battery cell 111 can be increased, making full use of the light. Of course, the first insulating layer 20 can also be transparent, so this application does not limit it here.

[0090] Specifically, the back contact battery assembly 100 may include a metal frame, a back plate, a front plate, a front adhesive film, and a back adhesive film.

[0091] The front plate 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 ultra-white glass can reach more than 92%, which can protect the battery cell 111 without affecting the efficiency of the battery cell 111 as much as possible. At the same time, the front adhesive film is arranged on one side of the front plate, and the battery series subassembly 10 is arranged on the side of the front adhesive film away from the front plate. The front adhesive film can bond the front plate and the battery cells of the battery series subassembly 10 together. The presence of the front adhesive film can seal and insulate the battery cell 111 and make it waterproof and moisture-proof.

[0092] Among them, the front film includes one or more of EVA, POE, EPE, and PVB. In this way, EVA film is low in price and has high light transmittance. POE film has good water vapor barrier effect and anti-PID effect. EPE film takes into account the advantages of EVA film and POE film, which is conducive to sealing components, improving the quality of components, and reducing costs. PVB film has higher penetration resistance and meets the performance requirements of glass curtain wall laminated safety glass.

[0093] See also Fig.14 The back plate 82 can be attached to the back adhesive film 81 on the back of the battery cell 111. The back plate 82 can protect and support the battery cell 111, and has reliable insulation, water resistance and aging resistance. There are multiple options for the back plate, which can usually be tempered glass, organic glass, aluminum alloy TPT composite film, KPC, CPC, etc. It can be set according to the specific situation and is not limited here.

[0094] The backing film 81 includes one or more of EVA, POE, EPE, and PVB. Thus, EVA film is cheap and has high light transmittance. POE film has good water vapor barrier effect and anti-PID effect. EPE film combines the advantages of EVA film and POE film, which is conducive to sealing components, improving component quality, and reducing costs. PVB film has higher penetration resistance and meets the performance requirements of glass curtain wall laminated safety glass. For example, please refer to Fig.14 The adhesive film 81 and the back plate 82 both have an opening area 83 at the lead wire 70, so that the lead wire 70 can be welded to the lead end 62 at the opening area 83 and can be extended to the welding terminal of the junction box.

[0095] The whole composed of the back plate 82, the battery cell 111, the front adhesive film, the back adhesive film 81 and the front plate can be set on a metal frame. The metal frame serves as the main external supporting structure of the entire back-contact battery assembly 100 and can provide stable support and installation for the back-contact battery assembly 100. For example, the back-contact battery assembly 100 can be installed at the required installation position through the metal frame.

[0096] On the other hand, an embodiment of the present application further provides a photovoltaic power generation system. It can be understood that the photovoltaic power generation system includes at least one back-contact battery assembly 100 as described above. It can be understood that the back-contact battery assemblies 100 can be electrically connected in parallel or in series, and the specific selection and setting can be made according to actual needs.

[0097] In this embodiment, the photovoltaic power generation system can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the photovoltaic power generation system are not limited to this, that is, the photovoltaic power generation system can be applied in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic power generation system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple back-contact battery assemblies 100. For example, multiple back-contact battery assemblies 100 can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid and then connected to the mains network to achieve solar power supply.

[0098] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments. In the description of this specification, the description of reference 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 representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0099] The back-contact battery assembly and photovoltaic power generation system provided in the embodiments of the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for technical personnel in this field, according to the ideas of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A back contact battery assembly, characterized in that: include: front panel; A front adhesive film, disposed on the front plate; At least two battery series subassemblies are arranged on the side of the front adhesive film away from the front plate, each of the battery series subassemblies includes at least one group of battery strings, each of the battery strings includes a plurality of battery cells connected in series, each of the battery cells includes a first electrode region and a second electrode region of opposite polarities located on the back of the battery cell, the first electrode region is provided with a first welding strip connected to a fine grid, and the second electrode region is provided with a second welding strip connected to a fine grid of another polarity; the battery cells in the battery string in one of the battery series subassemblies partially overlap with the battery cells in the battery string in another adjacent battery series subassembly, wherein the two overlapping battery cells are connected in parallel through the same first welding strip, and the first welding strip is located on the back side of the two overlapping battery cells; The middle bus bar is arranged on the back side of one of the two overlapping battery cells of the two battery series sub-assemblies. The middle bus bar is electrically connected to the first welding strip and is insulated from the second welding strip.

2. The back contact battery assembly according to claim 1, characterized in that: The battery cell is a busbar-less battery cell.

3. The back contact battery assembly according to claim 1, characterized in that: The back-contact battery assembly also includes an intermediate insulating layer, which is located on the side of the first welding strip away from the battery cell, and the intermediate insulating layer forms a first exposed area, and the first exposed area exposes the first welding strip; the intermediate bus bar is arranged on the side of the intermediate insulating layer away from the battery cell, and the intermediate insulating layer insulates the intermediate bus bar from the second welding strip, and the intermediate bus bar is conductively connected to the corresponding exposed first welding strip through the first exposed area.

4. The back contact battery assembly according to claim 3, characterized in that: The middle insulating layer covers the first welding strip and the second welding strip, and the middle insulating layer is provided with a first through hole forming the first exposed area.

5. The back contact battery assembly according to claim 3, characterized in that: The intermediate insulating layer includes a plurality of first intermediate insulating sublayers arranged at intervals, the plurality of first intermediate insulating sublayers cover the second welding strip, and the interval areas between adjacent first intermediate insulating sublayers form the first exposed area.

6. The back contact battery assembly according to claim 3, characterized in that: The intermediate bus bar includes a first conductive body, the intermediate insulating layer includes a plurality of second intermediate insulating sublayers spaced apart from each other, the second intermediate insulating sublayers are formed on the surface of the first conductive body, and the spaced areas between adjacent second intermediate insulating sublayers form the first exposed area.

7. The back contact battery assembly according to claim 3, characterized in that: The thickness of the intermediate insulating layer is between 0.05 mm and 0.8 mm.

8. The back contact battery assembly according to claim 3, characterized in that: The width of the intermediate insulating layer is greater than or equal to the width of the intermediate bus bar.

9. The back contact battery assembly according to any one of claims 1 to 8, characterized in that: Along the series connection direction of the battery cells in the battery string, the intermediate bus bar is located in the middle of one of the two battery cells of the two battery series sub-assemblies that overlap each other.

10. The back contact battery assembly according to any one of claims 1 to 8, characterized in that: A plurality of battery cells in each battery string are partially overlapped to form the battery string, and the contact regions between the overlaps are not conductively connected.

11. The back contact battery assembly according to claim 10, characterized in that: The overlapping areas of the adjacent battery cells in the battery string are provided with series welding strips to fixedly connect the adjacent battery cells, and the series welding strips connect the adjacent battery cells in series, wherein the series welding strips are located on the back side of the adjacent battery cells.

12. The back contact battery assembly according to claim 1, characterized in that: Each of the battery series subassemblies includes at least two battery strings. The battery strings in the battery series subassembly are arranged side by side. Two adjacent battery strings in the battery series subassembly are connected in series via a first bus bar, and the first bus bar is arranged on the back of the battery cell.

13. The back contact battery assembly according to claim 1, characterized in that: The intermediate bus bars include at least two, and the two intermediate bus bars include adjacent lead-out ends, and the lead-out ends are used to be connected to the junction box through lead-out wires; wherein the adjacent intermediate bus bars have different polarities.

14. The back contact battery assembly according to claim 13, characterized in that: The two intermediate bus bars are staggered or collinear with each other in the extension direction of the intermediate bus bar, and the spacing between the two lead wires of the adjacent lead end portions is equal to the spacing between the welding terminals in the junction box.

15. The back contact battery assembly according to claim 12, characterized in that: Along the series connection direction of the battery cells in the battery string, the first bus bar is located in the middle of the battery cells at the end positions in the battery string.

16. The back contact battery assembly according to claim 12, characterized in that: Two adjacent battery strings in each battery series-connected subassembly partially overlap.

17. A photovoltaic power generation system, characterized in that: Comprising a back contact battery assembly as described in any one of claims 1-16.

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