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 battery string is arranged on the side, away from the front plate, of the front adhesive film and provided with a plurality of battery pieces connected in series, each battery piece comprises a first electrode area and a second electrode area which are located on the back face of the battery piece and are opposite, and the first electrode areas and the second electrode areas are provided with welding strips connected with the fine grids; the first insulating layer is located on the side, away from the battery piece, of the welding strip, an exposed area is formed on the first insulating layer, and the exposed area exposes the welding strip of the first electrode area or the welding strip of the second electrode area; the first bus bar is arranged on the side, away from the battery piece, of the first insulating layer, the first bus bar is insulated from one of the first electrode area and the second electrode area through the first insulating layer, and the first bus bar is electrically connected with the exposed welding strip corresponding to the exposed area. Thus, even if the first insulating layer is arranged, it can be guaranteed that the welding strip is connected with enough fine grids, current can be better collected, and the first bus bar can be hidden.

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. Among them, the back-contact battery assembly includes a bus bar for connecting two battery strings in series. In order to hide the bus bar, it is set on the back of the battery in the related art. In order to prevent the battery cell from short-circuiting, an insulating layer is usually applied to the battery cell to insulate the bus bar from the battery cell as a whole. Although this method can prevent the bus bar from short-circuiting the battery cell, it will make the current collection effect poor. Utility Model Content

[0004] The embodiments of the present application provide a back-contact battery assembly and a photovoltaic power generation system, which can improve the current collection effect of the bus bar in the back-contact battery assembly.

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

[0006] front panel;

[0007] A front adhesive film, disposed on the front plate;

[0008] A battery string is arranged on a side of the front adhesive film away from the front plate, the battery string comprises a plurality of battery cells connected in series, each of the battery cells comprises a first electrode region and a second electrode region of opposite polarity located on the back of the battery cell, and the first electrode region and the second electrode region are respectively provided with a welding strip connected to a fine grid;

[0009] A first insulating layer is located on a side of the soldering strip away from the battery cell, the first insulating layer is formed with an exposed area, and the soldering strip of the first electrode region or the soldering strip of the second electrode region is exposed in the exposed area; and

[0010] A first bus bar is arranged on a side of the first insulating layer away from the battery cell, the first insulating layer insulates the first bus bar from one of the first electrode region and the second electrode region, and the first bus bar is conductively connected to the exposed welding strip corresponding to the exposed area.

[0011] Optionally, the battery cell is a busbar-less battery cell.

[0012] Optionally, the first insulating layer covers the soldering strip in the first electrode region and the soldering strip in the second electrode region, and the first insulating layer is provided with a through hole forming the exposed area.

[0013] Optionally, the first insulating layer includes a plurality of first insulating sublayers spaced apart from each other, the plurality of first insulating sublayers cover the welding strip of the first electrode region or the welding strip of the second electrode region, and the spacing area between adjacent first insulating sublayers forms the exposed area.

[0014] Optionally, the first busbar includes a conductive body, the first insulating layer includes a plurality of second insulating sublayers spaced apart from each other, the second insulating sublayers are formed on the conductive body, and the spaced areas between adjacent second insulating sublayers form the exposed areas.

[0015] Optionally, the thickness of the first insulating layer is between 0.05 mm and 0.8 mm.

[0016] Optionally, a width of the first insulating layer is greater than or equal to a width of the first bus bar.

[0017] Optionally, a plurality of the battery sheets are partially overlapped to form the battery string, and the contact regions between the overlaps are not conductively connected.

[0018] 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.

[0019] Optionally, along the series connection direction of the battery cells in the battery string, the first insulating layer and the first bus bar are located in the middle of the battery cells at the end positions in the battery string.

[0020] Optionally, the back-contact battery assembly includes at least two battery strings, the battery strings are arranged side by side, and two adjacent battery strings are connected in series via the first bus bar.

[0021] Optionally, two adjacent battery strings partially overlap.

[0022] Optionally, two battery strings arranged side by side and connected in series through the first bus bar form a battery series sub-assembly, and the back-contact battery assembly includes at least two groups of battery series sub-assemblies; along the series connection direction of the battery cells in the battery string, the two battery series sub-assemblies are arranged side by side with an interval, a second insulating layer is arranged between the two battery series sub-assemblies, the second insulating layer blocks the gap between the two battery series sub-assemblies, and an intermediate bus bar is arranged on the side of the second insulating layer away from the front side of the battery cells, and the intermediate bus bar connects the two battery series sub-assemblies in parallel.

[0023] Optionally, the first insulating layer and / or the second insulating layer is black or white or transparent.

[0024] 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.

[0025] The embodiment of the present application provides a back-contact battery assembly and a photovoltaic power generation system, wherein welding strips connected to fine grids are respectively provided in the first electrode region and the second electrode region on the back of the battery cell, so that the current of the fine grid can be conducted by the welding strips. In addition, a first insulating layer is provided on the side of the welding strip away from the battery cell, and the exposed area of ​​the first insulating layer exposes the welding strip of the first electrode region or the welding strip of the second electrode region, so that when the first bus bar is provided on the side of the first insulating layer away from the battery cell, the first insulating layer can insulate the first bus bar from one of the first electrode region and the second electrode region, and the first bus bar is conductively connected to the exposed welding strip corresponding to the exposed area, which prevents the battery cell from short-circuiting. At the same time, this structure can make the welding strip completely fit in the electrode region, and even if the first insulating layer is provided, it can ensure that the welding strip can be connected to enough fine grids, fully utilizing each fine grid on the battery cell, better collecting current, and improving the effect of collecting current. It can be understood that this structure of the back-contact battery assembly can effectively improve the effect of current collection while hiding the first bus bar. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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.

[0027] 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.

[0028] Figure 1A schematic diagram of the first partial structure of a back-contact battery assembly provided in an embodiment of the present application.

[0029] Figure 2 for Figure 1 A magnified schematic diagram of center A.

[0030] Figure 3 for Figure 2 A partial cross-sectional view at the through hole location.

[0031] Figure 4 It is a partial structural diagram of the welding strip, insulating layer and bus bar in the related technology.

[0032] Figure 5 A schematic diagram of the second partial structure of the back-contact battery assembly provided in an embodiment of the present application.

[0033] Figure 6 A schematic diagram of the connection between the first bus bar and the welding strip provided in an embodiment of the present application.

[0034] Figure 7 A schematic diagram of the partial structure of a battery series subassembly provided in an embodiment of the present application.

[0035] Figure 8 A schematic diagram of the structure of the intermediate bus bar provided in an embodiment of the present application.

[0036] Fig. 9 for Figure 1 A magnified schematic diagram of point B in the middle.

[0037] Reference numerals:

[0038] 100. Back contact battery assembly;

[0039] 10. Battery series subassembly; 11. Battery string; 111. Battery cell; 11a. First electrode region; 11b. Second electrode region;

[0040] 20, first insulating layer; 21, exposed area; 211, through hole; 22, first insulating sublayer; 23, second insulating sublayer;

[0041] 30. first bus bar; 31. conductive body;

[0042] 40. welding strip; 41. first welding strip; 42. second welding strip; 43. series welding strip;

[0043] 50. A second insulating layer;

[0044] 60. Intermediate bus bar. DETAILED DESCRIPTION

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] It should be noted that in the related art, multiple back-contact battery cells can be formed into a back-contact battery assembly through steps such as string welding, lamination, and packaging. Among them, the back-contact battery assembly includes a bus bar for connecting two battery strings in series. In order to hide the bus bar, it is set on the back of the battery in the related art. In order to prevent the battery cell from short-circuiting, an insulating layer is usually used to cover the battery cell to insulate the bus bar from the battery cell as a whole. Although this method can prevent the bus bar from short-circuiting the battery cell, it will make the current collection effect poor.

[0052] The embodiment of the present application provides a back-contact battery assembly and a photovoltaic power generation system, which can improve the current collection effect of the busbar in the back-contact battery assembly. In the present application, by setting a first insulating layer on the side of the welding strip away from the battery cell, and the exposed area of ​​the first insulating layer exposes the welding strip of the first electrode area or the welding strip of the second electrode area, so that when the first busbar is set on the side of the first insulating layer away from the battery cell, the first insulating layer can insulate the first busbar from one of the first electrode area and the second electrode area, and the first busbar is conductively connected to the exposed welding strip corresponding to the exposed area, which prevents the battery cell from short-circuiting. At the same time, this structure can make the welding strip completely fit in the electrode area. Even if the first insulating layer is set, it can ensure that the welding strip can be connected to enough fine grids, make full use of each fine grid on the battery cell, better collect current, and improve the effect of collecting current. It can be understood that this structure of the back-contact battery assembly can effectively improve the effect of current collection while hiding the first busbar. This will be explained in conjunction with the accompanying drawings below.

[0053] Based on this, see Figures 1 to 3 , the embodiment of the present application provides a back-contact battery assembly 100, including a battery string 11, a first insulating layer 20 and a first bus bar 30. Among them, the 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 and the second electrode region 11b are each provided with a welding strip 40 connected to the fine grid, so that the current of the fine grid can be conducted by the welding strip 40. It can be understood that Figure 1 and Figure 2As 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 40 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.

[0054] 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.

[0055] Please continue reading Figure 2 and Figure 3 In the embodiment of the present application, the first insulating layer 20 is disposed on the side of the soldering strip 40 away from the battery cell 111, and the first insulating layer 20 is formed with an exposed area 21, and the exposed area 21 exposes the soldering strip 40 of the first electrode region 11a or the soldering strip 40 of the second electrode region 11b. Among them, the first bus bar 30 is disposed 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 one of the first electrode region 11a and the second electrode region 11b, and the first bus bar 30 is conductively connected to the exposed soldering strip 40 corresponding to the exposed area 21. Thus, with the perspective when the back side of the battery cell 111 is facing upward as a reference, the first bus bar 30 is located on the top layer of the welding strip 40, or the welding strip 40 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 welding strip 40 can be completely attached to the electrode area, that is, it can ensure that the welding strip 40 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.

[0056] 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 40 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 40 and the fine grid. In this way, the more the welding strip 40 is attached to the battery cell 111, the more fine grids can be connected to it, thereby deriving more current. The less the welding strip 40 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 4 If the welding ribbon 40c is arranged on the side of the first bus bar 30c away from the battery cell 111, that is, with the perspective when the back side of the battery cell 111c faces upward as a reference, the welding ribbon 40c is arranged on the top layer of the first bus bar 30c. At this time, a part of the welding ribbon 40c will be blocked by the first bus bar 30c and the first insulating layer 20c, so that the welding ribbon 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 ribbon 40c, and the current of some fine grids is lost. In the present application, by setting the specific positions of the welding strip 40, the first insulating layer 20 and the first bus bar 30, and setting the specific structure of the first insulating layer 20, that is, by setting the first insulating layer 20 on the side of the welding strip 40 away from the battery cell 111, the first insulating layer 20 is formed with an exposed area 21, and the exposed area 21 exposes the welding strip 40 of the first electrode area 11a or the welding strip 40 of the second electrode area 11b, and the first bus bar 30 is set on the side of the first insulating layer 20 away from the battery cell 111. The first insulating layer 20 insulates the first bus bar 30 from one of the first electrode area 11a and the second electrode area 11b, and the first bus bar 30 is conductively connected to the welding strip 40 corresponding to the exposed area 21. Specifically, with the perspective when the back of the battery cell 111 is facing upward, please refer to Figure 3 The first bus bar 30 is located on the top layer of the welding strip 40, or in other words, the welding strip 40 is located on the side of the first bus bar 30 facing the battery cell 111. In this way, even if the first insulating layer 20 is provided, the welding strip 40 can be completely attached to the electrode area, that is, it can be ensured that the welding strip 40 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.

[0057] In some embodiments, in order to better connect the welding ribbon 40 to the first bus bar 30 and not prevent the welding ribbon 40 from being completely attached to the electrode area of ​​the battery cell 111, as shown in FIG. Figure 2 and Figure 3As shown, the first insulating layer 20 may be provided with a through hole 211 forming the exposed area 21, that is, the through hole 211 penetrating along the thickness direction of the first insulating layer 20 forms the exposed area 21. The first insulating layer 20 covers the welding strip 40 of the first electrode region 11a and the welding strip 40 of the second electrode region 11b, and since the first insulating layer 20 has the through hole 211, the through hole 211 can expose one of the welding strip 40 of the first electrode region 11a and the welding strip 40 of the second electrode region 11b, so that the first bus bar 30 can be connected to the welding strip 40 at the through hole 211, and the first insulating layer 20 can prevent the first bus bar 30 from short-circuiting the battery cell 111. In addition, due to the existence of the through hole 211, the first insulating layer 20 will not hinder the conductive connection between the first bus bar 30 and the welding strip 40, and it is also convenient to completely attach the welding strip 40 to the battery cell 111, so that the welding strip 40 can be connected to more fine grids.

[0058] For ease of understanding, please refer to Figure 2 The first electrode region 11a is provided with a first welding strip 41, and the second electrode region 11b is provided with a second welding strip 42. The first insulating layer 20 covers the first welding strip 41 of the first electrode region 11a and the second welding strip 42 of the second electrode region 11b, forming a through hole 211 in the exposed area 21 corresponding to the exposed second welding strip 42, so that the first bus bar 30 can be connected to the second welding strip 42 at the through hole 211.

[0059] Exemplarily, the first insulating layer 20 can be an insulating adhesive, or it can 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 side or both sides. It can be understood that the first insulating layer 20 can include materials such as ethylene-vinyl acetate copolymer, resin material, polyimide or polypropylene or polyethylene, and can also include an acrylic adhesive layer.

[0060] It should be noted that the thickness of the first insulating layer 20 cannot be too thick or too thin. If the first insulating layer 20 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 first insulating layer 20 can be set between 0.05 mm and 0.8 mm. In this way, the first insulating layer 20 will not be too thin or too thick. For example, the thickness of the first insulating layer 20 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.

[0061] The width of the first insulating layer 20 is greater than or equal to the width of the first bus bar 30. If the width of the first insulating layer 20 is too narrow, the first bus bar 30 will be exposed, and there is a risk of short circuit due to the first bus bar 30 contacting with the opposite electrode area or the opposite welding strip.

[0062] The first bus bar 30 may be a conventional bus bar or a bus bar with a special processing structure, such as a bus bar with a hollow, perforated, woven structure, etc. It is understandable that the special processing structure can effectively reduce the risk of poor solder joints caused by thermal stress deformation caused by temperature changes during welding, lamination, etc.

[0063] Alternatively, in some embodiments, in order not to prevent the soldering tape 40 from being completely attached to the electrode area of ​​the battery cell 111, please refer to Figure 5 The first insulating layer 20 includes a plurality of first insulating sublayers 22 arranged at intervals, and the plurality of first insulating sublayers 22 cover the welding strips 40 of the first electrode region 11a or the welding strips 40 of the second electrode region 11b, and the interval regions between adjacent first insulating sublayers 22 form bare regions 21. In this way, the first insulating sublayer 22 only covers the welding strips 40 that need to be insulated, and the welding strips 40 welded to the first bus bar 30 can be completely attached to the electrode region corresponding to the battery cell 111 due to the existence of the bare regions 21, so that the welding strips 40 can be connected to more fine grids.

[0064] For ease of understanding, please refer to Figure 5 The first electrode region 11a is provided with a first welding strip 41, and the second electrode region 11b is provided with a second welding strip 42. The first insulating sublayer 22 covers the first welding strip 41 of the first electrode region 11a, and the exposed area 21 exposes the second welding strip 42 correspondingly, so that the first bus bar 30 can be connected to the second welding strip 42 at the exposed area 21.

[0065] Exemplarily, the first insulating sublayer 22 can be an insulating adhesive, or it can 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 side or both sides. It can be understood that the first insulating sublayer 22 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] Alternatively, in some other embodiments, in order not to prevent the welding strip 40 from being completely attached to the electrode area of ​​the battery cell 111, please refer to Figure 6, the first bus bar 30 includes a conductive body 31, the first insulating layer 20 includes a plurality of second insulating sublayers 23 arranged at intervals, the second insulating sublayers 23 are formed on the surface of the conductive body 31, and the interval area of ​​adjacent second insulating sublayers 23 forms an exposed area 21. In this way, the welding strip 40 can be welded to the first bus bar 30 at the exposed area 21, and since the conductive body 31 of the first bus bar 30 is covered by the second insulating sublayer 23 except for the exposed area 21, when the first bus bar 30 is set on the battery cell 111, the second insulating layer 50 can prevent the first bus bar 30 from being electrically connected to the welding strip 40 that needs to be insulated. The existence of the exposed area 21 can make the welding strip 40 welded to the first bus bar 30 completely fit on the electrode area corresponding to the battery cell 111, so that the welding strip 40 can be connected to more fine grids.

[0067] Exemplarily, the second insulating sublayer 23 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 second insulating sublayer can include materials such as ethylene-vinyl acetate copolymer, resin material, polyimide or polypropylene or polyethylene, and can also include an acrylic adhesive layer. Of course, the second insulating sublayer 23 can also be an insulating coating directly applied on the conductive body 31, and the thickness of the insulating coating can be between 5 microns and 150 microns, which is not limited in this application.

[0068] It can be understood that through the setting of the above-mentioned structure, the first bus bar 30 can be hidden on the back side of the back contact battery assembly 100, so that the appearance color of the front side of the assembly can be made consistent, such as achieving a full black effect, which is conducive to the full black design of the back contact battery assembly 100.

[0069] 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.

[0070] In some embodiments, see Figure 7 The back-contact battery assembly 100 includes at least two battery strings 11 , which are arranged side by side, and two adjacent battery strings 11 are connected in series through a first bus bar 30 .

[0071] In the extension direction of the first bus bar 30 (such as the first direction H1), two adjacent battery strings 11 may partially overlap each other. In this way, the first bus bar 30 can be better hidden. Of course, in some other embodiments, in the extension direction of the first bus bar 30, if two adjacent battery strings 11 are arranged at intervals, a first insulating layer 20 may be arranged in the interval area to shield the first bus bar 30 in the interval area.

[0072] Understandably, see Figures 7 and 8 , two battery strings 11 arranged side by side and connected in series through the first bus bar 30 form a battery series subassembly 10, and the back contact battery assembly 100 includes at least two groups of battery series subassemblies 10. Along the series connection direction of the battery cells 111 in the battery string 11 (such as the second direction H2), the two battery series subassemblies 10 are arranged side by side at intervals, and a second insulating layer 50 is arranged between the two battery series subassemblies 10, and the second insulating layer 50 blocks the gap between the two battery series subassemblies 10. The side of the second insulating layer 50 away from the front of the battery cell 111 is provided with an intermediate bus bar 60, and the intermediate bus bar 60 connects the two battery series subassemblies 10 in parallel.

[0073] It can be understood that the second insulating layer 50 can be black, white or transparent, wherein when the second insulating layer 50 is black, the middle bus bar 60 can be better shielded.

[0074] 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.

[0075] In the battery series subassembly 10, each battery string 11 includes a plurality of battery cells 111 connected in series. Fig. 9, 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, there is no need to set conductive glue or other adhesive glue between the overlapped areas, and the battery cells are only 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.

[0076] 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.

[0077] 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.

[0078] Among them, 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 cells 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 transmission loss of the welding ribbon 40 and the risk of edge cracking can be reduced.

[0079] Exemplarily, the thickness of the first bus bar 30 may be between 0.06 mm and 0.3 mm, and the width may be between 8 mm and 20 mm. The first bus bar 30 may be made of tinned copper bus bar, conductive copper foil or aluminum-based copper strip.

[0080] It is understandable that in some other embodiments, the back contact battery assembly 100 may also include a metal frame, a back plate, a front plate, a front adhesive film, and a back adhesive film.

[0081] The front panel 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 panel, and the battery string is arranged on the side of the front adhesive film away from the front panel. The front adhesive film can bond the front panel and the battery cells of the battery string together. The presence of the front adhesive film can seal and insulate the battery cell 111 and make it waterproof and moisture-proof.

[0082] 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.

[0083] The backplane can be attached to the adhesive film on the back of the battery cell 111. The backplane can protect and support the battery cell 111 and has reliable insulation, water resistance and aging resistance. There are multiple options for the backplane, which can usually be tempered glass, organic glass, aluminum alloy TPT composite film, KPC, CPC, etc. The specific settings can be made according to the specific situation and are not limited here.

[0084] The adhesive film includes one or more of EVA, POE, EPE, and PVB. In this way, EVA film is cheap 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.

[0085] The whole composed of the back plate, the battery cell 111, the front adhesive film, the back adhesive film 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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, It is characterized in that include: front panel; A front adhesive film, disposed on the front plate; A battery string is arranged on a side of the front adhesive film away from the front plate, the battery string comprises a plurality of battery cells connected in series, each of the battery cells comprises a first electrode region and a second electrode region of opposite polarity located on the back of the battery cell, and the first electrode region and the second electrode region are respectively provided with a welding strip connected to a fine grid; A first insulating layer is located on a side of the welding strip away from the battery cell, the first insulating layer is formed with an exposed area, and the exposed area exposes the welding strip of the first electrode area or the welding strip of the second electrode area; and A first bus bar is arranged on a side of the first insulating layer away from the battery cell, the first insulating layer insulates the first bus bar from one of the first electrode region and the second electrode region, and the first bus bar is conductively connected to the exposed welding strip corresponding to the exposed area.

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

3. The back contact battery assembly according to claim 1, It is characterized in that The first insulating layer covers the soldering strip in the first electrode region and the soldering strip in the second electrode region, and the first insulating layer is provided with a through hole forming the exposed area.

4. The back contact battery assembly according to claim 1, It is characterized in that The first insulating layer includes a plurality of first insulating sublayers spaced apart from each other, the plurality of first insulating sublayers cover the welding strips of the first electrode region or the welding strips of the second electrode region, and the spaced regions between adjacent first insulating sublayers form the exposed regions.

5. The back contact battery assembly according to claim 1, It is characterized in that The first busbar includes a conductive body, the first insulating layer includes a plurality of second insulating sublayers spaced apart from each other, the second insulating sublayers are formed on the surface of the conductive body, and the spaced areas between adjacent second insulating sublayers form the exposed area.

6. The back contact battery assembly according to claim 1, It is characterized in that The thickness of the first insulating layer is between 0.05 mm and 0.8 mm.

7. The back contact battery assembly according to claim 1, It is characterized in that The width of the first insulating layer is greater than or equal to the width of the first bus bar.

8. The back contact battery assembly according to any one of claims 1 to 7, It is characterized in that A plurality of the battery sheets are partially overlapped to form the battery string, and the contact areas between the overlaps are not conductively connected.

9. The back contact battery assembly according to claim 8, It is 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.

10. The back contact battery assembly according to any one of claims 1 to 7, It is characterized in that Along the series connection direction of the battery cells in the battery string, the first insulating layer and the first bus bar are located in the middle of the battery cells at the end positions in the battery string.

11. The back contact battery assembly according to claim 1, It is characterized in that The back-contact battery assembly includes at least two battery strings, which are arranged side by side, and two adjacent battery strings are connected in series via the first bus bar.

12. The back contact battery assembly according to claim 11, It is characterized in that Two adjacent battery strings partially overlap each other.

13. The back contact battery assembly according to claim 11, It is characterized in that The two battery strings arranged side by side and connected in series through the first bus bar form a battery series sub-assembly, and the back-contact battery assembly includes at least two groups of battery series sub-assemblies; along the series connection direction of the battery cells in the battery string, the two battery series sub-assemblies are arranged side by side with an interval, and a second insulating layer is arranged between the two battery series sub-assemblies, the second insulating layer blocks the gap between the two battery series sub-assemblies, and an intermediate bus bar is arranged on the side of the second insulating layer away from the front of the battery cell, and the intermediate bus bar connects the two battery series sub-assemblies in parallel.

14. The back contact battery assembly according to claim 13, It is characterized in that The first insulating layer and / or the second insulating layer is black, white or transparent.

15. A photovoltaic power generation system, It is characterized in that Comprising a back contact battery assembly as described in any one of claims 1-14.

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