Back contact battery assembly and preparation method thereof, and photovoltaic power generation system

Abstract

The invention discloses a back contact battery assembly and a preparation method thereof. The back contact battery assembly comprises a battery string; the main welding strip comprises a first main welding strip and a second main welding strip; the insulating layer is located on the side, away from the battery piece, of the main welding strip, and the bus bar is insulated from the first main welding strip and the second main welding strip through the insulating layer; the bus bar is arranged on one side, deviating from the battery piece, of the insulating layer; the auxiliary welding strip is arranged on the side, away from the battery piece, of the bus bar, the auxiliary welding strip is electrically connected with the bus bar, and the auxiliary welding strip is electrically connected with one of the first main welding strip and the second main welding strip.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a back-contact battery assembly and a preparation method thereof. Background Art

[0002] The 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 technology. However, in order to achieve the connection between the bus bar and the welding strip of the same polarity, a complex process is often required, such as opening a hole at a preset position of the bus bar, and then injecting solder paste into the hole position. The solder paste is connected to the welding strip of the same polarity at the same time to achieve electrical connection with the welding strip of the same polarity. This method has a complex process and high operating precision. It is not easy to automate production and is not conducive to large-scale production. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a back-contact battery assembly, which can achieve electrical connection between the bus bar and the welding strip of the same polarity without complicated processes while hiding the bus bar, which is conducive to realizing automated production and has low requirements for automation precision, which is conducive to improving production yield.

[0004] The technical problem to be solved by the present invention is also to provide a method for preparing a back-contact battery assembly, which is conducive to realizing automated production and does not require high automation accuracy, thereby helping to improve production yield.

[0005] In order to solve the above problems, the present invention provides a back contact battery assembly, comprising:

[0006] A battery string, wherein the battery string comprises at least two battery cells connected in series, each of the battery cells comprises a first doping region and a second doping region located on the back of the battery cell, a first gate line is disposed on the first doping region, and a second gate line is disposed on the second doping region;

[0007] A main welding strip, the main welding strip comprising a first main welding strip and a second main welding strip, the first main welding strip is electrically connected to the first gate line, and the second main welding strip is electrically connected to the second gate line;

[0008] An insulating layer, located on a side of the main welding strip facing away from the battery cell, wherein the insulating layer insulates the bus bar from the first main welding strip and the second main welding strip;

[0009] A bus bar, the bus bar is arranged on a side of the insulating layer away from the battery cell;

[0010] A secondary welding strip, wherein the secondary welding strip is arranged on a side of the bus bar away from the battery cell, the secondary welding strip is electrically connected to the bus bar, and the secondary welding strip is electrically connected to one of the first main welding strip and the second main welding strip.

[0011] In some embodiments, the insulating layer covers the main welding strip, and the contact point between the main welding strip and the edge of the insulating layer includes a first contact point and a second contact point;

[0012] The secondary welding strip crosses the insulating layer along the extension direction of the main welding strip and is in electrical contact with the first contact point and the second contact point respectively.

[0013] In some embodiments, one end of the secondary welding strip extends beyond the first contact point;

[0014] And / or, the other end of the auxiliary welding strip exceeds the second contact point.

[0015] In some embodiments, the auxiliary welding strip includes a first auxiliary welding strip and a second auxiliary welding strip, the first auxiliary welding strip is electrically connected to the first main welding strip, and the second auxiliary welding strip is electrically connected to the second main welding strip.

[0016] In some embodiments, the first secondary welding strip is electrically connected to the first main welding strip, and the second secondary welding strip is not provided;

[0017] Alternatively, the second auxiliary welding strip is electrically connected to the second main welding strip, and the first auxiliary welding strip is not provided.

[0018] In some embodiments, the main welding strip and the auxiliary welding strip both extend along the second direction, the insulating layer and the bus bar both extend along the first direction, and the first direction intersects with the second direction.

[0019] In some embodiments, the width of the insulating layer is greater than or equal to the width of the bus bar.

[0020] In some embodiments, along the series connection direction of the battery cells in the battery string, the insulating layer and the bus bar are located in the middle area of ​​the battery cells at the end positions in the battery string.

[0021] In some embodiments, the insulating layer is black or white or transparent.

[0022] In some embodiments, the solar cell is a busbarless solar cell.

[0023] In some embodiments, the secondary main grid is electrically connected to the bus bar by welding.

[0024] In some embodiments, the secondary main grid is electrically connected to the first main welding strip by welding.

[0025] In some embodiments, the secondary main grid is electrically connected to the second main welding strip by welding.

[0026] To solve the above problems, the present invention also provides a method for preparing a back contact battery assembly, comprising the following steps:

[0027] A plurality of cells are placed on the assembly of the front plate and the front adhesive film, wherein the back of the cell has a first doping region and a second doping region, the first doping region is provided with a first gate line, and the second doping region is provided with a second gate line;

[0028] Connecting the battery cells in series to form a battery string through main welding strips, wherein the main welding strips include a first main welding strip and a second main welding strip, the first main welding strip is electrically connected to the first grid line, and the second main welding strip is electrically connected to the second grid line;

[0029] Placing an insulating layer on the main welding strip, the insulating layer is located on a side of the main welding strip away from the battery cell, and the insulating layer insulates the bus bar from the first main welding strip and the second main welding strip;

[0030] Placing a bus bar on the insulating layer, wherein the bus bar is arranged on a side of the insulating layer away from the battery cell;

[0031] Placing an auxiliary welding strip on the bus bar, the auxiliary welding strip being arranged on a side of the bus bar away from the battery cell, the auxiliary welding strip being electrically connected to the bus bar, and the auxiliary welding strip being electrically connected to one of the first main welding strip and the second main welding strip, to form a semi-finished product;

[0032] A front plate and a front adhesive film are placed on one side of the semi-finished product, and a back adhesive film and a back plate are placed on the other side of the semi-finished product to form a laminated part, and the laminated part is laminated to obtain a finished product.

[0033] And, a method for preparing a back contact battery assembly, comprising the following steps:

[0034] A plurality of cells are placed on the assembly of the front plate and the front adhesive film, wherein the back of the cell has a first doping region and a second doping region, the first doping region is provided with a first gate line, and the second doping region is provided with a second gate line;

[0035] Connecting the battery cells in series to form a battery string through main welding strips, wherein the main welding strips include a first main welding strip and a second main welding strip, the first main welding strip is electrically connected to the first grid line, and the second main welding strip is electrically connected to the second grid line;

[0036] An insulating layer, a bus bar and an auxiliary welding tape assembly are placed on the main welding tape, the assembly is located on a side of the main welding tape away from the battery cell, the insulating layer insulates the bus bar from the first main welding tape and the second main welding tape, a bus bar and an auxiliary welding tape are sequentially arranged on the insulating layer, the auxiliary welding tape is electrically connected to the bus bar, and the auxiliary welding tape is electrically connected to one of the first main welding tape and the second main welding tape, to form a semi-finished product;

[0037] A front plate and a front adhesive film are placed on one side of the semi-finished product, and a back adhesive film and a back plate are placed on the other side of the semi-finished product to form a laminated part, and the laminated part is laminated to obtain a finished product.

[0038] In some embodiments, the secondary main grid is electrically connected to the bus bar by welding.

[0039] In some embodiments, the secondary main grid is electrically connected to the first main welding strip by welding.

[0040] In some embodiments, the secondary main grid is electrically connected to the second main welding strip by welding.

[0041] In some embodiments, connecting the battery cells in series through a main welding ribbon to form a battery string includes:

[0042] The battery string includes at least three battery cells, the first main welding strip electrically connects the first grid lines of two adjacent battery cells, and the second main welding strip electrically connects the second grid lines of two adjacent battery cells.

[0043] In some embodiments, the first main welding strip is electrically connected to the first gate line by welding;

[0044] And / or, the second main welding strip is electrically connected to the second gate line by welding.

[0045] In some embodiments, the insulating layer, bus bar and secondary welding tape assembly are prepared by the following method:

[0046] Placing a bus bar on the insulating layer to obtain a semi-finished assembly;

[0047] A secondary welding strip is placed at a preset position of the semi-finished assembly to obtain the assembly.

[0048] In some embodiments, the preset position includes a first preset position and a second preset position;

[0049] Placing a first secondary welding strip on a first preset position of the semi-finished assembly so that the first secondary welding strip is electrically connected to the first main welding strip to obtain a first assembly;

[0050] Alternatively, a second secondary welding strip is placed at a second preset position of the semi-finished assembly so that the second secondary welding strip is electrically connected to the second main welding strip to obtain a second assembly.

[0051] Correspondingly, the present invention also provides a photovoltaic power generation system, comprising the back-contact cell assembly or a back-contact cell assembly prepared by the method for preparing the back-contact cell assembly described above.

[0052] The implementation of the present invention has the following beneficial effects:

[0053] The back-contact battery assembly provided by the present invention has a first doping region and a second doping region on the back side of the battery cell, a first grid line is provided on the first doping region, and a second grid line is provided on the second doping region, and by providing a first main welding strip electrically connected to the first grid line and a second main welding strip electrically connected to the second grid line, the current of the first fine grid and the second fine grid can be conducted by the first main welding strip and the second main welding strip.

[0054] In addition, an insulating layer is arranged on the side of the main welding strip facing away from the battery cell, and the insulating layer insulates the bus bar from the first main welding strip and the second main welding strip. The insulating layer isolates the bus bar and the main welding strip, preventing the bus bar from being connected to the heterogeneous welding strip, thereby preventing the battery cell from short circuiting. At the same time, by adding an insulating layer, the welding strip can be completely attached to the electrode area, ensuring that the welding strip can be connected to enough fine grids, making full use of each fine grid on the battery cell, better collecting current, and improving the effect of collecting current.

[0055] Furthermore, a bus bar is arranged on the side of the insulating layer away from the battery cell, and the bus bar is used to collect the current on the welding strip of the same polarity. Furthermore, when the bus bar is hidden on the back contact battery assembly, the current collection effect can be effectively improved by arranging the above-mentioned main welding strip and insulating layer.

[0056] Furthermore, a secondary welding strip is provided on a side of the bus bar away from the battery cell, the secondary welding strip is electrically connected to the bus bar, and the secondary welding strip is electrically connected to one of the first main welding strip and the second main welding strip. By adding the secondary welding strip, the bus bar can be electrically connected to the welding strip of the same polarity without complicated processes.

[0057] In the preparation method of the back-contact battery assembly provided by the present invention, the main welding strip and the battery cell are welded by welding, and the main welding strip, the bus bar and the auxiliary welding strip are electrically connected by welding, thereby avoiding other complicated manufacturing processes such as opening holes in the insulating layer. This is conducive to realizing automated production, and does not require high automation accuracy, which is conducive to improving production yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 is a schematic structural diagram of a back contact battery assembly provided by the present invention;

[0059] Figure 2 It is a flow chart of a method for preparing a back contact battery assembly provided by the present invention;

[0060] Figure 3 It is a flow chart of another method for preparing a back contact battery assembly provided by the present invention. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0062] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention 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 invention.

[0063] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0064] In the description of the present invention, 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 the present invention can be understood according to specific circumstances.

[0065] In the present invention, 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.

[0066] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the examples of various specific processes and materials provided by the present invention, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0067] In the present invention, "preferred" and "better" are only used to describe implementation methods or embodiments with better effects, and it should be understood that they do not constitute a limitation on the scope of protection of the present invention. In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features. In the present invention, when involving numerical ranges, unless otherwise specified, the two endpoints of the numerical range are included.

[0068] The present invention provides a back contact battery assembly, such as Figure 1 As shown, including:

[0069] A battery string 100, wherein the battery string 100 comprises at least two battery cells connected in series, each of the battery cells comprises a first doping region and a second doping region located on the back of the battery cell, a first gate line is disposed on the first doping region, and a second gate line is disposed on the second doping region;

[0070] A main welding strip 200, wherein the main welding strip 200 comprises a first main welding strip 200 and a second main welding strip 200, wherein the first main welding strip 200 is electrically connected to the first gate line, and the second main welding strip 200 is electrically connected to the second gate line;

[0071] An insulating layer 300 is located on a side of the main welding strip 200 away from the battery cell, and the insulating layer 300 insulates the bus bar 400 from the first main welding strip 200 and the second main welding strip 200;

[0072] A bus bar 400, wherein the bus bar 400 is disposed on a side of the insulating layer 300 away from the battery cell;

[0073] The auxiliary welding strip 500 is arranged on a side of the bus bar 400 away from the battery cell, the auxiliary welding strip 500 is electrically connected to the bus bar 400, and the auxiliary welding strip 500 is electrically connected to one of the first main welding strip 200 and the second main welding strip 200.

[0074] The above technical solution is described in detail below:

[0075] (i) Battery string 100 refers to a single power source formed by connecting the negative electrodes of multiple battery cells to the positive electrode of the next battery cell. The battery string 100 is connected in series, that is, by connecting the negative electrode of the first battery cell to the positive electrode of the second battery cell, and the negative electrode of the second battery cell to the positive electrode of the third battery cell, and so on, until all battery cells are connected together in this way. In some embodiments, the battery string 100 may include two battery cells connected in series, three battery cells connected in series, or other larger numbers of battery cells. The number of battery cells to be connected in series can be determined based on actual usage.

[0076] Solar cells, generally speaking, are sheet-like structures, and 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. A solar cell in which electrodes of both polarities are formed on the back side of the cell is a back-contact cell. In some embodiments, when the solar cell 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. The shape of the solar cell can be rectangular or square, and the four corners of the solar cell can have standard corners, cut corners, or rounded corners, which are specifically set according to actual production needs and are not specifically limited here. In some embodiments, the solar cell is a busbarless solar cell. A busbarless solar cell eliminates the busbar line of the solar cell, collects the fine grid current through the welding ribbon of the component, and realizes the battery structure of interconnecting the batteries. Busbarless solar cells can save silver consumption because the battery has no busbar, and more welding ribbons and fine grid contact points reduce the risk of hidden cracks in the solar cell, thereby improving the long-term reliability of the component.

[0077] Doping region, not shown in the figure, refers to a region with specific electrical properties formed in a semiconductor material by a doping process. These regions can be N-type or P-type. N-type doping usually uses pentavalent elements such as phosphorus (P) and arsenic (As), while P-type doping uses trivalent elements such as boron (B) and aluminum (Al). By performing N-type and P-type doping in different regions, a PN junction can be formed. The PN junction is one of the most basic structures in a solar cell and has photoelectric conversion characteristics. In some embodiments, a P-type silicon wafer is selected to form a PN junction after phosphorus diffusion. Among them, after the semiconductor structure absorbs solar energy, it excites and generates electron-hole pairs, and 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. In some embodiments, each cell includes a first doping region and a second doping region of opposite sex located on the back of the cell, the first doping region is a P-type doping region, and the second doping region is an N-type doping region. Correspondingly, the first gate line is a P-type gate line, and the second gate line is an N-type gate line. In some other embodiments, the first doping region is an N-type doping region, and the second doping region is a P-type doping region. Correspondingly, the first gate line is an N-type gate line, and the second gate line is a P-type gate line. In some embodiments, the back side of the back contact cell includes first doping regions and second doping regions alternately distributed along a second direction, such as, including a plurality of P-type doping regions and N-type doping regions alternately arranged. In some embodiments, the first doping region and the second doping region are both parallel to the first direction. In some embodiments, the first direction is the lateral direction of the cell, and the second direction is the longitudinal direction of the cell. The number of the first doping region and the second doping region is determined according to the actual cell size, the width and distance of the P-type gate line and the N-type gate line, and is not specifically limited here.

[0078] The first grid line and the second grid line, which are not shown in the figure, are usually made of silver, aluminum or other conductive materials, and are printed or deposited on the first doped area and the second doped area. The main function of the first grid line and the second grid line is to quickly collect and transmit the electrons generated by the solar cell under light. When sunlight shines on the silicon wafer, the silicon material converts light energy into electrical energy, generating electrons and holes. The function of the first grid line and the second grid line is to guide these electrons to the welding strip of the battery assembly so that they can be collected and used by the external circuit. In some embodiments, the first grid line and the second grid line are arranged alternately along the second direction. In some embodiments, the first grid line and the second grid line both extend along the first direction. In some embodiments, the first direction is the lateral direction of the battery cell, and the second direction is the longitudinal direction of the battery cell. The number of the first grid line and the second grid line is determined according to the actual size of the battery cell, the width and distance of the P-type grid line and the N-type grid line, and is not specifically limited here.

[0079] (ii) Main welding strip 200, also known as tinned copper strip or tin-coated copper strip, is an important auxiliary material for connecting photovoltaic module cells, and plays an important role in connecting cells and transmitting current. The main welding strip 200 includes a first main welding strip 200 and a second main welding strip 200, the first main welding strip 200 is electrically connected to the first grid line, and the second main welding strip 200 is electrically connected to the second grid line. By providing a first main welding strip 200 electrically connected to the first grid line and a second main welding strip 200 electrically connected to the second grid line, the current of the first fine grid and the second fine grid can be conducted by the first main welding strip 200 and the second main welding strip 200. In some embodiments, the first main welding strip 200 and the second main welding strip 200 both extend along the second direction. In some embodiments, the first direction is the transverse direction of the cell, and the second direction is the longitudinal direction of the cell. In some embodiments, the battery string 100 includes at least three battery cells, the first main welding strip 200 electrically connects the first grid lines of two adjacent battery cells, and the second main welding strip 200 electrically connects the second grid lines of two adjacent battery cells. The number of the first main welding strip 200 and the second main welding strip 200 is determined according to the actual size of the battery cell, the width and distance of the first main welding strip 200 and the second main welding strip 200, and is not specifically limited here.

[0080] (III) An insulating layer 300, located on the side of the main welding strip 200 away from the battery cell, and the insulating layer 300 insulates the bus bar 400 from the first main welding strip 200 and the second main welding strip 200. In some embodiments, the insulating layer 300 is 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 side or both sides. It can be understood that the insulating layer 300 may include materials such as ethylene vinyl acetate copolymer, resin material, polyimide, polypropylene or polyethylene, and may also include an acrylic adhesive layer.

[0081] The thickness of the insulating layer 300 cannot be too thick or too thin. If the insulating layer 300 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. In some embodiments, the thickness of the insulating layer 300 is 0.05 mm to 0.8 mm. In this way, the insulating layer 300 is neither too thin nor too thick. Exemplary thicknesses of the insulating layer 300 are 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, and 0.8 mm, but are not limited to the above.

[0082] In some embodiments, the insulating layer 300 extends along a first direction; preferably, the length of the insulating layer 300 along the first direction is the same as the length of the battery cell, and the insulating layer 300 is continuous and uninterrupted, so that it is easier to set the insulating layer 300 on the battery cell and more conducive to automated production.

[0083] In some embodiments, the width of the insulating layer 300 is greater than or equal to the width of the busbar 400. If the width of the insulating layer 300 is too narrow, the busbar 400 will be exposed, and there is a risk that the busbar 400 will contact the heterogeneous doped region or heterogeneous solder strip, thereby causing a short circuit problem.

[0084] In some embodiments, the insulating layer 300 is black, white or transparent. The insulating layer 300 can be black, so that the busbar 400 can be better hidden. The insulating layer 300 can also be white, so that the reflected light from the back of the battery cell to the battery cell can be increased, making full use of the light. Of course, the insulating layer 300 can also be transparent. The present invention does not specifically limit the color of the insulating layer 300.

[0085] (iv) Busbar 400, the busbar 400 is arranged on the side of the insulating layer 300 away from the battery cell; busbar 400 is a metal conductive bar connecting the battery cells, usually made of materials with good conductivity such as silver, aluminum or copper, and the main function of busbar 400 is to collect the current on the battery cell and transmit it to the output end of the component. In some embodiments, the busbar 400 extends along a first direction; preferably, the length of the busbar 400 along the first direction is the same as the length of the battery cell, and the busbar 400 is continuous and uninterrupted, so that it is easier to set the busbar 400 on the battery cell and more conducive to automated production.

[0086] In some embodiments, along the series connection direction of the battery cells in the battery string 100, the insulating layer 300 and the bus bar 400 are located in the middle area of ​​the battery cells at the end positions in the battery string 100. In this way, the bus bar 400 can be hidden on the back of the back contact battery assembly, so that the appearance color of the front of the assembly is consistent, such as achieving a full black effect, which is conducive to the full black design of the back contact battery assembly. It can also effectively shorten the transmission distance of the current and reduce the risk of transmission loss and edge cracking of the welding strip.

[0087] (V) Auxiliary welding strip 500, wherein the auxiliary welding strip 500 is arranged on a side of the bus bar 400 away from the battery cell, the auxiliary welding strip 500 is electrically connected to the bus bar 400, and the auxiliary welding strip 500 is electrically connected to one of the first main welding strip 200 and the second main welding strip 200.

[0088] In some embodiments, the material of the secondary welding tape 500 is the same as that of the primary welding tape 200 , and may be a tinned copper tape or a tin-coated copper tape.

[0089] In some embodiments, the insulating layer 300 covers the main welding strip 200, and the contact points between the main welding strip 200 and the edge of the insulating layer 300 include a first contact point and a second contact point; the auxiliary welding strip 500 spans the insulating layer 300 along the extension direction of the main welding strip 200, and is in electrical contact with the first contact point and the second contact point respectively. Preferably, one end of the auxiliary welding strip 500 exceeds the first contact point; and / or, the other end of the auxiliary welding strip 500 exceeds the second contact point.

[0090] In some embodiments, the auxiliary welding strip 500 includes a first auxiliary welding strip 500 and a second auxiliary welding strip 500, the first auxiliary welding strip 500 is electrically connected to the first main welding strip 200, and the second auxiliary welding strip 500 is electrically connected to the second main welding strip 200; if the first auxiliary welding strip 500 is electrically connected to the first main welding strip 200, the second auxiliary welding strip 500 is not set; or, if the second auxiliary welding strip 500 is electrically connected to the second main welding strip 200, the first auxiliary welding strip 500 is not set.

[0091] In some embodiments, the main welding strip 200 and the auxiliary welding strip 500 both extend along the second direction, the insulating layer 300 and the bus bar 400 both extend along the first direction, and the first direction intersects the second direction. Preferably, the first direction and the second direction are perpendicular.

[0092] In some embodiments, the auxiliary main grid is electrically connected to the bus bar 400 by welding; the auxiliary main grid is electrically connected to the first main welding strip 200 by welding; and the auxiliary main grid is electrically connected to the second main welding strip 200 by welding. In other words, in some embodiments, the main welding strip 200 and the battery cell are welded by welding, and the main welding strip 200, the bus bar 400 and the auxiliary welding strip 500 are electrically connected by welding, which avoids other complicated manufacturing processes such as opening holes in the insulating layer 300, which is conducive to realizing automated production, and does not require high automation precision, which is conducive to improving production yield.

[0093] In summary, the back-contact battery assembly provided by the present invention has a first doping region and a second doping region on the back of the battery cell, a first gate line is provided on the first doping region, and a second gate line is provided on the second doping region, and by providing a first main welding strip 200 electrically connected to the first gate line and a second main welding strip 200 electrically connected to the second gate line, the current of the first fine grid and the second fine grid can be conducted by the first main welding strip 200 and the second main welding strip 200.

[0094] In addition, an insulating layer 300 is arranged on the side of the main welding strip 200 away from the battery cell. The insulating layer 300 insulates the bus bar 400 from the first main welding strip 200 and the second main welding strip 200. The insulating layer 300 isolates the bus bar 400 and the main welding strip 200, preventing the bus bar 400 from being connected to the heterogeneous welding strip, thereby preventing the battery cell from short-circuiting. At the same time, by adding the insulating layer 300, the welding strip can be completely attached to the electrode area, ensuring that the welding strip can be connected to enough fine grids, making full use of each fine grid on the battery cell, better collecting current, and improving the effect of collecting current.

[0095] Furthermore, a bus bar 400 is arranged on the side of the insulating layer 300 away from the battery cell, and the bus bar 400 is used to collect the current on the welding strip of the same polarity. Furthermore, when the bus bar 400 is hidden on the back contact battery assembly, the current collection effect can be effectively improved by arranging the above-mentioned main welding strip 200 and insulating layer 300.

[0096] Furthermore, a secondary welding strip 500 is provided on a side of the bus bar 400 away from the battery cell, the secondary welding strip 500 is electrically connected to the bus bar 400, and the secondary welding strip 500 is electrically connected to one of the first main welding strip 200 and the second main welding strip 200. By adding the secondary welding strip 500, the bus bar 400 can be electrically connected to the welding strip of the same polarity without complicated processes.

[0097] Accordingly, the present invention provides a method for preparing a back contact battery assembly, such as Figure 2 As shown, the following steps are included:

[0098] A plurality of cells are placed on the assembly of the front plate and the front adhesive film, wherein the back of the cell has a first doping region and a second doping region, the first doping region is provided with a first gate line, and the second doping region is provided with a second gate line;

[0099] The battery cells are connected in series through a main welding strip 200 to form a battery string 100, wherein the main welding strip 200 includes a first main welding strip 200 and a second main welding strip 200, wherein the first main welding strip 200 is electrically connected to the first grid line, and the second main welding strip 200 is electrically connected to the second grid line;

[0100] An insulating layer 300 is placed on the main welding strip 200, the insulating layer 300 is located on a side of the main welding strip 200 away from the battery cell, and the insulating layer 300 insulates the bus bar 400 from the first main welding strip 200 and the second main welding strip 200;

[0101] A bus bar 400 is placed on the insulating layer 300 , and the bus bar 400 is arranged on a side of the insulating layer 300 away from the battery cell;

[0102] A secondary welding tape 500 is placed on the bus bar 400, the secondary welding tape 500 is arranged on a side of the bus bar 400 away from the battery cell, the secondary welding tape 500 is electrically connected to the bus bar 400, and the secondary welding tape 500 is electrically connected to one of the first main welding tape 200 and the second main welding tape 200, to form a semi-finished product;

[0103] A front plate and a front adhesive film are placed on one side of the semi-finished product, and a back adhesive film and a back plate are placed on the other side of the semi-finished product to form a laminated part, and the laminated part is laminated to obtain a finished product.

[0104] Furthermore, the present invention also provides a method for preparing a back contact battery assembly, such as Figure 3 As shown, the following steps are included:

[0105] A plurality of cells are placed on the assembly of the front plate and the front adhesive film, wherein the back of the cell has a first doping region and a second doping region, the first doping region is provided with a first gate line, and the second doping region is provided with a second gate line;

[0106] The battery cells are connected in series through a main welding strip 200 to form a battery string 100, wherein the main welding strip 200 includes a first main welding strip 200 and a second main welding strip 200, wherein the first main welding strip 200 is electrically connected to the first grid line, and the second main welding strip 200 is electrically connected to the second grid line;

[0107] An insulating layer 300, a bus bar 400 and an auxiliary welding tape 500 assembly are placed on the main welding tape 200, the assembly is located on the side of the main welding tape 200 away from the battery cell, the insulating layer 300 insulates the bus bar 400 from the first main welding tape 200 and the second main welding tape 200, the bus bar 400 and the auxiliary welding tape 500 are sequentially arranged on the insulating layer 300, the auxiliary welding tape 500 is electrically connected to the bus bar 400, and the auxiliary welding tape 500 is electrically connected to one of the first main welding tape 200 and the second main welding tape 200, to form a semi-finished product;

[0108] A front plate and a front adhesive film are placed on one side of the semi-finished product, and a back adhesive film and a back plate are placed on the other side of the semi-finished product to form a laminated part, and the laminated part is laminated to obtain a finished product.

[0109] In the above two preparation methods, in some embodiments, the auxiliary main grid is electrically connected to the bus bar 400 by welding; the auxiliary main grid is electrically connected to the first main welding strip 200 by welding; and the auxiliary main grid is electrically connected to the second main welding strip 200 by welding. In some embodiments, the first main welding strip 200 is electrically connected to the first grid line by welding; and / or, the second main welding strip 200 is electrically connected to the second grid line by welding. That is to say, in some embodiments, the main welding strip 200 and the battery cell are welded by welding, and the main welding strip 200, the bus bar 400 and the auxiliary welding strip 500 are electrically connected by welding, which avoids other complex manufacturing processes such as opening holes in the insulating layer 300, which is conducive to realizing automated production, and does not require high automation accuracy, which is conducive to improving production yield.

[0110] In addition, in some embodiments, the battery cells are connected in series through the main welding ribbon 200 to form a battery string 100, including: the battery string 100 includes at least 3 battery cells, the first main welding ribbon 200 electrically connects the first grid lines of two adjacent battery cells, and the second main welding ribbon 200 electrically connects the second grid lines of two adjacent battery cells.

[0111] In some embodiments, the insulating layer 300, the bus bar 400 and the secondary welding ribbon 500 assembly are manufactured by the following method:

[0112] A bus bar 400 is placed on the insulating layer 300 to obtain a semi-finished assembly; an auxiliary welding strip 500 is placed at a preset position of the semi-finished assembly to obtain an assembly. Preferably, the preset position includes a first preset position and a second preset position; a first auxiliary welding strip 500 is placed at the first preset position of the semi-finished assembly so that the first auxiliary welding strip 500 is electrically connected to the first main welding strip 200 to obtain a first assembly; or a second auxiliary welding strip 500 is placed at the second preset position of the semi-finished assembly so that the second auxiliary welding strip 500 is electrically connected to the second main welding strip 200 to obtain a second assembly.

[0113] In some embodiments, a front panel, such as photovoltaic glass, may cover the adhesive film on the front side of the cell. The front panel may 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 cell without affecting the efficiency of the cell as much as possible.

[0114] At the same time, the front adhesive film can bond the front panel and the battery cell together. The presence of the front adhesive film can seal, insulate, and protect the battery cell from water and moisture.

[0115] In some embodiments, the backplane can be attached to the adhesive film on the back of the battery cell. The backplane can protect and support the battery cell 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 adhesive film, KPC, CPC, etc. It can be set according to specific circumstances and is not limited here. The whole composed of the backplane, battery cell, adhesive film and front plate can be set on a metal frame. The metal frame serves as the main external support structure of the entire back contact battery assembly and can stably support and install the back contact battery assembly. For example, the back contact battery assembly can be installed at the required installation position through the metal frame.

[0116] At the same time, the adhesive film can bond the optical backplane and the battery cell together. The presence of the adhesive film can seal, insulate, and make the battery cell waterproof and moisture-proof.

[0117] Furthermore, the present invention also provides a photovoltaic power generation system 1, including the back contact battery assembly or the back contact battery assembly prepared by the preparation method of the back contact battery assembly described above. The photovoltaic power generation system 1 can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water surface power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the photovoltaic power generation system 1 are not limited to this, that is, the photovoltaic power generation system 1 can be applied in all fields where solar energy is required to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic power generation system 1 may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple battery assemblies 10. For example, multiple battery assemblies 10 can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter to convert it into the alternating current required by the mains power grid and then connected to the mains network to realize solar power supply.

[0118] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0119] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A back contact battery assembly, characterized in that: include: A battery string, wherein the battery string comprises at least two battery cells connected in series, each of the battery cells comprises a first doping region and a second doping region located on the back of the battery cell, a first gate line is disposed on the first doping region, and a second gate line is disposed on the second doping region; A main welding strip, the main welding strip comprising a first main welding strip and a second main welding strip, the first main welding strip is electrically connected to the first gate line, and the second main welding strip is electrically connected to the second gate line; An insulating layer, located on a side of the main welding strip facing away from the battery cell, wherein the insulating layer insulates the bus bar from the first main welding strip and the second main welding strip; A bus bar, the bus bar is arranged on a side of the insulating layer away from the battery cell; A secondary welding strip, wherein the secondary welding strip is arranged on a side of the bus bar away from the battery cell, the secondary welding strip is electrically connected to the bus bar, and the secondary welding strip is electrically connected to one of the first main welding strip and the second main welding strip.

2. The back contact battery assembly according to claim 1, characterized in that: The insulating layer covers the main welding strip, and the contact points between the main welding strip and the edge of the insulating layer include a first contact point and a second contact point; The secondary welding strip crosses the insulating layer along the extension direction of the main welding strip and is in electrical contact with the first contact point and the second contact point respectively.

3. The back contact battery assembly according to claim 2, characterized in that: One end of the secondary welding strip exceeds the first contact point; And / or, the other end of the auxiliary welding strip exceeds the second contact point.

4. The back contact battery assembly according to claim 1, characterized in that: The auxiliary welding strip includes a first auxiliary welding strip and a second auxiliary welding strip, the first auxiliary welding strip is electrically connected to the first main welding strip, and the second auxiliary welding strip is electrically connected to the second main welding strip.

5. The back contact battery assembly according to claim 4, characterized in that: The first auxiliary welding strip is electrically connected to the first main welding strip, and the second auxiliary welding strip is not provided; Alternatively, the second auxiliary welding strip is electrically connected to the second main welding strip, and the first auxiliary welding strip is not provided.

6. The back contact battery assembly according to claim 1, characterized in that: The main welding strip and the auxiliary welding strip both extend along the second direction, the insulating layer and the bus bar both extend along the first direction, and the first direction intersects with the second direction.

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

8. The back contact battery assembly according to claim 1, characterized in that: Along the series connection direction of the battery cells in the battery string, the insulating layer and the bus bar are located in the middle area of ​​the battery cells at the end positions in the battery string.

9. The back contact battery assembly according to claim 1, characterized in that: The insulating layer is black, white or transparent.

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

11. The back contact battery assembly according to claim 1, characterized in that: The auxiliary main grid is electrically connected to the bus bar by welding.

12. The back contact battery assembly according to claim 1, characterized in that: The auxiliary main grid is electrically connected to the first main welding strip by welding.

13. The back contact battery assembly according to claim 1, characterized in that: The auxiliary main grid is electrically connected to the second main welding strip by welding.

14. A method for preparing a back contact battery assembly according to any one of claims 1 to 13, characterized in that: The following steps are involved: A plurality of cells are placed on the assembly of the front plate and the front adhesive film, wherein the back of the cell has a first doping region and a second doping region, the first doping region is provided with a first gate line, and the second doping region is provided with a second gate line; Connecting the battery cells in series to form a battery string through main welding strips, wherein the main welding strips include a first main welding strip and a second main welding strip, the first main welding strip is electrically connected to the first grid line, and the second main welding strip is electrically connected to the second grid line; Placing an insulating layer on the main welding strip, the insulating layer is located on a side of the main welding strip away from the battery cell, and the insulating layer insulates the bus bar from the first main welding strip and the second main welding strip; Placing a bus bar on the insulating layer, wherein the bus bar is arranged on a side of the insulating layer away from the battery cell; Placing an auxiliary welding strip on the bus bar, the auxiliary welding strip being arranged on a side of the bus bar away from the battery cell, the auxiliary welding strip being electrically connected to the bus bar, and the auxiliary welding strip being electrically connected to one of the first main welding strip and the second main welding strip, to form a semi-finished product; A front plate and a front adhesive film are placed on one side of the semi-finished product, and a back adhesive film and a back plate are placed on the other side of the semi-finished product to form a laminated part, and the laminated part is laminated to obtain a finished product.

15. A method for preparing a back contact battery assembly according to any one of claims 1 to 13, characterized in that: The following steps are involved: A plurality of cells are placed on the assembly of the front plate and the front adhesive film, wherein the back of the cell has a first doping region and a second doping region, the first doping region is provided with a first gate line, and the second doping region is provided with a second gate line; Connecting the battery cells in series to form a battery string through main welding strips, wherein the main welding strips include a first main welding strip and a second main welding strip, the first main welding strip is electrically connected to the first grid line, and the second main welding strip is electrically connected to the second grid line; An insulating layer, a bus bar and an auxiliary welding tape assembly are placed on the main welding tape, the assembly is located on a side of the main welding tape away from the battery cell, the insulating layer insulates the bus bar from the first main welding tape and the second main welding tape, a bus bar and an auxiliary welding tape are sequentially arranged on the insulating layer, the auxiliary welding tape is electrically connected to the bus bar, and the auxiliary welding tape is electrically connected to one of the first main welding tape and the second main welding tape, to form a semi-finished product; A front plate and a front adhesive film are placed on one side of the semi-finished product, and a back adhesive film and a back plate are placed on the other side of the semi-finished product to form a laminated part, and the laminated part is laminated to obtain a finished product.

16. The method for preparing a back contact battery assembly according to claim 14 or 15, characterized in that: The auxiliary main grid is electrically connected to the bus bar by welding.

17. The method for preparing a back contact battery assembly according to claim 14 or 15, characterized in that: The auxiliary main grid is electrically connected to the first main welding strip by welding.

18. The method for preparing a back contact battery assembly according to claim 14 or 15, characterized in that: The auxiliary main grid is electrically connected to the second main welding strip by welding.

19. The method for preparing a back contact battery assembly according to claim 14 or 15, characterized in that: The method of connecting the battery cells in series through the main welding strip to form a battery string comprises: The battery string includes at least three battery cells, the first main welding strip electrically connects the first grid lines of two adjacent battery cells, and the second main welding strip electrically connects the second grid lines of two adjacent battery cells.

20. The method for preparing a back contact battery assembly according to claim 19, characterized in that: The first main welding strip is electrically connected to the first gate line by welding; And / or, the second main welding strip is electrically connected to the second gate line by welding.

21. The method for preparing a back contact battery assembly according to claim 15, characterized in that: The insulating layer, bus bar and auxiliary welding strip assembly are prepared by the following method: Placing a bus bar on the insulating layer to obtain a semi-finished assembly; A secondary welding strip is placed at a preset position of the semi-finished assembly to obtain the assembly.

22. The method for preparing a back contact battery assembly according to claim 21, characterized in that: The preset position includes a first preset position and a second preset position; Placing a first secondary welding strip on a first preset position of the semi-finished assembly so that the first secondary welding strip is electrically connected to the first main welding strip to obtain a first assembly; Alternatively, a second secondary welding strip is placed at a second preset position of the semi-finished assembly so that the second secondary welding strip is electrically connected to the second main welding strip to obtain a second assembly.

23. A photovoltaic power generation system, characterized in that: A method for preparing a back-contact battery assembly comprising the back-contact battery assembly as described in any one of claims 1-13 or the back-contact battery assembly as described in any one of claims 14-22.

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