Back contact module and manufacturing method

Abstract

Disclosed in the present disclosure are a back contact module and a manufacturing method. The module comprises: a cell string; busbar ribbons comprising first busbar ribbons and second busbar ribbons; an insulating layer on the side of the busbar ribbons facing away from cells; a busbar on the side of the insulating layer facing away from the cells; and interconnect ribbons electrically connected to the busbar and electrically connected to one of the first busbar ribbons and the second busbar ribbons.

Description

Back contact module and preparation method

[0001] Cross-reference to related applications

[0002] The present disclosure refers to the Chinese patent application No. 202411353910.8 entitled "Back contact module and preparation method, photovoltaic power generation system" filed on September 26, 2024, which is incorporated by reference in its entirety into the present disclosure. TECHNICAL FIELD

[0003] The present disclosure relates to the field of photovoltaic technology, in particular, especially relates to a back contact module and a preparation method. BACKGROUND

[0004] The back contact cell is formed into a back contact module through steps such as series welding, laminating and packaging. The back contact module includes a busbar for connecting two cell strings in series. In order to hide the busbar, the busbar is arranged on the back of the cell in the related art. However, in order to realize the connection between the busbar and the solder strip of the same polarity, a complex process is often required, for example, a hole is formed at a predetermined position of the busbar, and then tin paste is injected into the hole, and the tin paste is connected to the solder strip of the same polarity to realize the electrical connection between the busbar and the solder strip of the same polarity. This method is complex and requires high operation precision, and is not easy to automate production, which is not conducive to large-scale production.

[0005] SUMMARY

[0006] The technical problem to be solved by the present disclosure is to provide a back contact module which can realize the electrical connection between the busbar and the solder strip of the same polarity without complex process while hiding the busbar, which is conducive to automated production and does not require high automation precision, and is conducive to improving the production yield.

[0007] The technical problem to be solved by the present disclosure is also to provide a preparation method of a back contact module, which is conducive to automated production and does not require high automation precision, and is conducive to improving the production yield.

[0008] In order to solve the above problems, the present disclosure provides a back contact module, comprising:

[0009] a cell string, the cell string comprising at least two series-connected cell pieces, each cell piece comprising a first doped region and a second doped region on the back of the cell piece, the first doped region being provided with a first grid line, and the second doped region being provided with a second grid line;

[0010] a main solder strip, the main solder strip comprising a first main solder strip and a second main solder strip, the first main solder strip being electrically connected to the first grid line, and the second main solder strip being electrically connected to the second grid line;

[0011] an insulating layer, located on the side of the main solder strip away from the cell piece;

[0012] The busbar is arranged on the side of the insulating layer away from the cell sheet, and the insulating layer insulates the busbar from the first main tab and the second main tab;

[0013] The sub-tab is arranged on the side of the busbar away from the cell sheet, the sub-tab is electrically connected with the busbar, and the sub-tab is electrically connected with one of the first main tab and the second main tab.

[0014] In some embodiments, the insulating layer covers the main tab, and the contact points of the main tab with the edges of the insulating layer include a first contact point and a second contact point;

[0015] The sub-tab crosses the insulating layer along the extension direction of the main tab and is electrically connected with the first contact point and the second contact point, respectively.

[0016] In some embodiments, one end of the sub-tab exceeds the first contact point, or the other end of the sub-tab exceeds the second contact point, or one end of the sub-tab exceeds the first contact point and the other end of the sub-tab exceeds the second contact point.

[0017] In some embodiments, the sub-tab includes a first sub-tab and a second sub-tab, the first sub-tab is electrically connected with the first main tab, and the second sub-tab is electrically connected with the second main tab.

[0018] In some embodiments, the first sub-tab is electrically connected with the first main tab, and the second sub-tab is not arranged;

[0019] Or, the second sub-tab is electrically connected with the second main tab, and the first sub-tab is not arranged.

[0020] In some embodiments, the main tab and the sub-tab extend along a second direction, the insulating layer and the busbar extend along a first direction, and the first direction and the second direction intersect.

[0021] In some embodiments, the width of the insulating layer is greater than or equal to the width of the busbar.

[0022] In some embodiments, along the series connection direction of the cell sheets in the battery string, the insulating layer and the busbar are located in the middle region of the cell sheet at the end position in the battery string.

[0023] In some embodiments, the insulating layer is black or white or transparent.

[0024] In some embodiments, the cell sheet is a main grid-free cell sheet.

[0025] In some embodiments, the sub-tab is electrically connected with the busbar by welding.

[0026] In some embodiments, the sub-tab is electrically connected with the first main tab by welding.

[0027] In some embodiments, the sub-bussing is electrically connected to the second main bussing by soldering.

[0028] To solve the above problems, the present disclosure also provides a preparation method of a back contact module, comprising the following steps:

[0029] Placing a plurality of battery pieces on the combination of the front plate and the front adhesive film, the back surface of the battery piece having a first doped region and a second doped region, the first doped region being provided with a first grid line, and the second doped region being provided with a second grid line;

[0030] Serially connecting the battery pieces by a main bussing to form a battery string, the main bussing comprising a first main bussing and a second main bussing, the first main bussing being electrically connected to the first grid line, and the second main bussing being electrically connected to the second grid line;

[0031] Placing an insulating layer on the main bussing, the insulating layer being located on the side of the main bussing away from the battery piece, the insulating layer insulating the busbar from the first main bussing and the second main bussing; placing a busbar on the insulating layer, the busbar being located on the side of the insulating layer away from the battery piece; placing a sub-bussing on the busbar, the sub-bussing being located on the side of the busbar away from the battery piece, the sub-bussing being electrically connected to the busbar, and the sub-bussing being electrically connected to one of the first main bussing and the second main bussing, to form a semi-finished product; or,

[0032] Placing the combination of the insulating layer, the busbar and the sub-bussing on the main bussing, the combination being located on the side of the main bussing away from the battery piece, the insulating layer insulating the busbar from the first main bussing and the second main bussing, the busbar and the sub-bussing being sequentially arranged on the insulating layer, the sub-bussing being electrically connected to the busbar, and the sub-bussing being electrically connected to one of the first main bussing and the second main bussing, to form the semi-finished product;

[0033] Placing a front plate and a front adhesive film on one side of the semi-finished product, and placing a back adhesive film and a back plate on the other side of the semi-finished product, to form a to-be-laminated piece, laminating the to-be-laminated piece, to obtain a finished product.

[0034] In addition, a preparation method of a back contact module is provided, comprising the following steps:

[0035] Placing a plurality of battery pieces on the combination of the front plate and the front adhesive film, the back surface of the battery piece having a first doped region and a second doped region, the first doped region being provided with a first grid line, and the second doped region being provided with a second grid line;

[0036] Serially connecting the battery pieces by a main bussing to form a battery string, the main bussing comprising a first main bussing and a second main bussing, the first main bussing being electrically connected to the first grid line, and the second main bussing being electrically connected to the second grid line;

[0037] placing the assembly of the insulating layer, the busbar and the auxiliary welding strip on the main welding strip, the assembly being located on the side of the main welding strip away from the battery piece, the insulating layer insulating the busbar from the first main welding strip and the second main welding strip, the busbar and the auxiliary welding strip being sequentially arranged on the insulating layer, the auxiliary welding strip being electrically connected with the busbar, and the auxiliary welding strip being electrically connected with one of the first main welding strip and the second main welding strip, to form a semi-finished product;

[0038] placing a front plate and a front adhesive film on one side of the semi-finished product, and placing a back adhesive film and a back plate on the other side of the semi-finished product, to form a to-be-laminated product, laminating the to-be-laminated product to obtain a finished product.

[0039] In some embodiments, the auxiliary welding strip is electrically connected with the busbar by welding.

[0040] In some embodiments, the auxiliary welding strip is electrically connected with the first main welding strip by welding.

[0041] In some embodiments, the auxiliary welding strip is electrically connected with the second main welding strip by welding.

[0042] In some embodiments, the battery pieces are connected in series by the main welding strip to form a battery string, comprising:

[0043] The battery string comprises at least 3 battery pieces, the first main welding strip electrically connecting the first grid lines of two adjacent battery pieces, and the second main welding strip electrically connecting the second grid lines of the two adjacent battery pieces.

[0044] In some embodiments, the first main welding strip is electrically connected with the first grid line by welding; or, the second main welding strip is electrically connected with the second grid line by welding; or, the first main welding strip is electrically connected with the first grid line by welding, and the second main welding strip is electrically connected with the second grid line by welding.

[0045] In some embodiments, the assembly of the insulating layer, the busbar and the auxiliary welding strip is prepared by the following method:

[0046] placing the busbar on the insulating layer to obtain an assembly semi-finished product;

[0047] placing the auxiliary welding strip on the preset position of the assembly semi-finished product to obtain the assembly.

[0048] In some embodiments, the preset position comprises a first preset position and a second preset position.

[0049] placing the first auxiliary welding strip on the first preset position of the assembly semi-finished product, so that the first auxiliary welding strip is electrically connected with the first main welding strip, to obtain a first assembly;

[0050] Or, a second sub-welding strip is placed in a second preset position of the assembly semi-finished product, so that the second sub-welding strip is electrically connected with the second main welding strip, and a second assembly is obtained.

[0051] Correspondingly, the disclosure also provides a photovoltaic power generation system comprising the back contact assembly or the back contact assembly prepared by the preparation method of the back contact assembly.

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

[0053] The back contact assembly provided by the disclosure is provided with a first doped region and a second doped region on the back surface of the cell piece, a first grid line is arranged on the first doped region, and a second grid line is arranged on the second doped region. By arranging the first main welding strip electrically connected with the first grid line and the second main welding strip electrically connected with 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] And, an insulating layer is arranged on the side of the main welding strip away from the cell piece, 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, prevents the bus bar from being connected with the opposite welding strip, and prevents the cell piece from being short-circuited; at the same time, by additionally arranging the insulating layer, the welding strip can be completely attached to the electrode area, it is ensured that the welding strip can be connected with a sufficient number of fine grids, each fine grid on the cell piece is fully utilized, the current is better collected, and the effect of collecting the current is improved.

[0055] Furthermore, the bus bar is arranged on the side of the insulating layer away from the cell piece, and the bus bar is used for collecting the current on the welding strip of the same polarity. Further, when the bus bar is hidden on the back contact assembly, by arranging the main welding strip and the insulating layer, the effect of collecting the current can be effectively improved.

[0056] Further, the sub-welding strip is arranged on the side of the bus bar away from the cell piece, the sub-welding strip is electrically connected with the bus bar, and the sub-welding strip is electrically connected with one of the first main welding strip and the second main welding strip. By increasing the sub-welding strip, the bus bar can be electrically connected with the welding strip of the same polarity without complex process.

[0057] In the preparation method of the back contact assembly provided by the disclosure, the main welding strip and the cell piece are welded by welding, and the main welding strip, the bus bar and the sub-welding strip are electrically connected by welding, which avoids other complex manufacturing processes such as hole opening on the insulating layer, which is conducive to realizing automatic production and has low requirements for automatic precision, and is conducive to improving the production yield. BRIEF DESCRIPTION OF DRAWINGS

[0058] FIG. 1 is a structural schematic diagram of the back contact assembly provided by the disclosure;

[0059] FIG. 2 is a flowchart of one preparation method of the back contact assembly provided by the disclosure.

[0060] Reference signs: 100, battery string; 200, main welding strip; 300, insulation layer; 400, busbar; 500, sub welding strip. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below in combination with the drawings and embodiments. The examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present disclosure, and cannot be understood as a limitation on the present disclosure. In addition, it should be understood that the specific embodiments described herein are only used to explain the present disclosure and cannot be used to limit the present disclosure.

[0062] In the description of the present disclosure, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present disclosure and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present disclosure.

[0063] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more features. In the description of the present disclosure, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0064] In the description of the present disclosure, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present disclosure can be understood according to the specific circumstances.

[0065] In the present disclosure, unless specifically stated and limited otherwise, a first feature "on" or "under" a second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "over" the second feature includes that the first feature is directly above and obliquely above the second feature, or only means that the first feature is higher in horizontal height than the second feature. The first feature "under", "below" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or only means that the first feature is lower in horizontal height than the second feature.

[0066] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present disclosure. For the purpose of simplifying the present disclosure, the components and settings of specific examples are described in the following. Of course, they are only examples, and the purpose is not to limit the present disclosure. In addition, the present disclosure can repeatedly refer to reference numerals and / or reference letters in different examples, and such 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 disclosure provides examples of various specific processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0067] In the present disclosure, "preferably", "more preferably" only describe the implementation manner or embodiment with better effect, and it should be understood that it does not constitute a limitation on the protection scope of the present disclosure. In the present disclosure, in the technical features described in an open manner, both the closed technical solution composed of the listed features and the open technical solution containing the listed features are included. In the present disclosure, if no special instructions are given, the numerical interval includes both endpoints of the numerical interval.

[0068] The present disclosure provides a back contact assembly, as shown in FIG. 1, comprising:

[0069] A battery string 100, the battery string 100 comprising at least 2 pieces of series-connected battery pieces, each battery piece comprising a first doped region and a second doped region on the back surface of the battery piece, the first doped region being provided with a first grid line, and the second doped region being provided with a second grid line;

[0070] A main solder strip 200, the main solder strip 200 comprising a first main solder strip 200 and a second main solder strip 200, the first main solder strip 200 being electrically connected with the first grid line, and the second main solder strip 200 being electrically connected with the second grid line;

[0071] An insulating layer 300, located on the side of the main solder strip 200 away from the battery piece;

[0072] The bus bar 400 is arranged on the side of the insulating layer 300 away from the battery piece, and the insulating layer 300 insulates the bus bar 400 from the first main solder strip 200 and the second main solder strip 200;

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

[0074] The above technical solutions are described in detail below:

[0075] (1) The battery string 100 refers to a single power source formed by connecting the negative electrode of a plurality of battery pieces to the positive electrode of the next battery piece. The connection mode of the battery string 100 is series connection, that is, by connecting the negative electrode of the first battery piece to the positive electrode of the second battery piece, the negative electrode of the second battery piece to the positive electrode of the third battery piece, and so on, until all the battery pieces are connected together in this way. In some embodiments, the battery string 100 can include two battery pieces in series, three battery pieces in series, or more battery pieces in series, and the number of battery pieces to be connected in series can be determined according to actual use.

[0076] The battery piece is generally in a sheet structure, 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. Both polar electrodes are formed on the back side of the solar cell, which is a back contact solar cell. In some embodiments, when the battery piece is normally used and installed, the side facing up is called the front side, and the other side opposite the front side is called the back side. The shape of the battery piece can be rectangular or square, and the four corners of the battery piece can have standard corners, cut corners, or rounded corners, which can be set according to actual production needs and are not limited here. In some embodiments, the battery piece is a main grid-free battery piece. The main grid-free battery piece cancels the main grid line of the battery piece, collects fine grid current through the solder strip of the module, and realizes battery interconnection. The main grid-free battery piece can save silver consumption because the battery has no main grid, and more solder strip and fine grid contact points reduce the risk of battery piece cracking and improve the long-term reliability of the module.

[0077] Doped regions, not shown in the figure, are regions of a semiconductor material that have been formed by a doping process to have specific electrical properties. These regions can be either N-type or P-type. N-type doping typically uses pentavalent elements such as phosphorus (P), arsenic (As), etc., while P-type doping uses trivalent elements such as boron (B), aluminum (Al), etc. By performing N-type and P-type doping in different regions, a P-N junction can be formed. The P-N junction is one of the basic structures in a solar cell, and has the property of converting light into electricity. In some embodiments, a P-type silicon wafer is selected, and after phosphorus diffusion, a P-N junction is formed. In some embodiments, each cell includes a first doped region and a second doped region on the back of the cell, the first doped region is a P-type doped region, and the second doped region is an N-type doped region. Correspondingly, the first grid line is a P-type grid line, and the second grid line is an N-type grid line. In some other embodiments, the first doped region is an N-type doped region, and the second doped region is a P-type doped region. Correspondingly, the first grid line is an N-type grid line, and the second grid line is a P-type grid line. In some embodiments, the back of the back contact cell includes first doped regions and second doped regions that are alternately distributed along a second direction, such as a plurality of P-type doped regions and N-type doped regions that are alternately arranged. In some embodiments, the first doped regions and the second doped regions are both parallel to the first direction. In some embodiments, the first direction is a lateral direction of the cell, and the second direction is a longitudinal direction of the cell. The number of the first doped regions and the second doped regions is determined according to the actual size of the cell, the width and distance of the P-type grid line and the N-type grid line, and is not specifically limited herein.

[0078] First and second grid lines, not shown in the figure, are typically made of silver, aluminum or other conductive materials, and are printed or deposited on the first and second doped regions. The main function of the first and second grid lines is to quickly collect and transport the electrons generated by the solar cell under light. When sunlight shines on the silicon wafer, the silicon material will convert light energy into electrical energy to generate electrons and holes. The function of the first and second grid lines is to guide these electrons to the ribbon of the cell assembly, so that they can be collected and utilized by the external circuit. In some embodiments, the first and second grid lines are alternately arranged along the second direction. In some embodiments, the first and second grid lines both extend along the first direction. In some embodiments, the first direction is a lateral direction of the cell, and the second direction is a longitudinal direction of the cell. The number of the first and second grid lines is determined according to the actual size of the cell, the width and distance of the P-type grid line and the N-type grid line, and is not specifically limited herein.

[0079] (ii) main solder ribbons 200, also known as solder ribbons, tin-coated copper ribbons or tin-coated copper ribbons, are important auxiliary materials for connecting photovoltaic module cells, playing an important role in connecting cells and transmitting current. The main solder ribbons 200 include first main solder ribbons 200 and second main solder ribbons 200, the first main solder ribbons 200 are electrically connected with the first grid lines, and the second main solder ribbons 200 are electrically connected with the second grid lines. By setting the first main solder ribbons 200 electrically connected with the first grid lines and the second main solder ribbons 200 electrically connected with the second grid lines, the current of the first fine grid and the second fine grid can be conducted by the first main solder ribbons 200 and the second main solder ribbons 200. In some embodiments, the first main solder ribbons 200 and the second main solder ribbons 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 cell string 100 includes at least 3 cells, the first main solder ribbons 200 electrically connect the first grid lines of two adjacent cells, and the second main solder ribbons 200 electrically connect the second grid lines of two adjacent cells. The number of first main solder ribbons 200 and second main solder ribbons 200 is determined according to the actual size of the cell, the width and distance of the first main solder ribbons 200 and the second main solder ribbons 200, which is not limited here.

[0080] (iii) an insulation layer 300 is located on the side of the main solder ribbons 200 away from the cell, and the insulation layer 300 insulates the bus bar 400 from the first main solder ribbons 200 and the second main solder ribbons 200. In some embodiments, the insulation layer 300 is an insulating glue, which can also be a non-conductive adhesive tape or an insulating film, such as a PET or PI adhesive tape with acrylic or silicone glue, or a PET or PI substrate with a single-sided or double-sided film of ethylene-vinyl acetate copolymer or hot melt adhesive. It can be understood that the insulation layer 300 can include ethylene-vinyl acetate copolymer, resin material, polyimide or polypropylene or polyethylene material, and can also include an acrylic adhesive layer.

[0081] The thickness of the insulation layer 300 cannot be too thick or too thin. If the insulation layer 300 is too thin, it is not convenient to operate when pasting, and it is easy to deform when pulling, and there is a risk of damage to long-term insulation. If it is too thick, it will increase the height difference, and the stress generated during the lamination process will cause the pieces to be broken, increasing the risk of false welding. In some embodiments, the thickness of the insulation layer 300 is 0.05mm to 0.8mm. In this way, the insulation layer 300 will neither be too thin nor too thick. The exemplary thickness of the insulation layer 300 is 0.05mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, but is not limited to the above list.

[0082] In some embodiments, the insulating layer 300 extends along the first direction; in some implementations, the length of the insulating layer 300 along the first direction is the same as the length of the cell sheet, and the insulating layer 300 is continuous and uninterrupted, so that it is easier to set the insulating layer 300 on the cell sheet, 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 bus bar 400. If the width of the insulating layer 300 is too narrow, the bus bar 400 will be exposed, and there is a risk that the bus bar 400 will contact the differently doped area or the differently soldered ribbon, thereby causing a short circuit.

[0084] In some embodiments, the insulating layer 300 is black or white or transparent. The insulating layer 300 can be black, so that the bus bar 400 can be better hidden. The insulating layer 300 can also be white, so that the reflected light from the back of the cell sheet can be reflected to the cell sheet, making full use of the light. Of course, the insulating layer 300 can also be transparent. The present disclosure does not make specific limitations on the color of the insulating layer 300.

[0085] (Four) the bus bar 400, the bus bar 400 is arranged on the side of the insulating layer 300 away from the cell sheet; the bus bar 400 is a metal conductive strip for connecting the cell sheet, which is usually made of materials with good conductive properties such as silver, aluminum or copper, and the main function of the bus bar 400 is to collect the current on the cell sheet and transmit it to the output end of the module. In some embodiments, the bus bar 400 extends along the first direction; in some implementations, the length of the bus bar 400 along the first direction is the same as the length of the cell sheet, and the bus bar 400 is continuous and uninterrupted, so that it is easier to set the bus bar 400 on the cell sheet, and more conducive to automated production.

[0086] In some embodiments, along the series connection direction of the cell sheets in the cell string 100, the insulating layer 300 and the bus bar 400 are located in the middle region of the cell sheet at the end position in the cell string 100. In this way, the bus bar 400 can be hidden on the back of the back contact module, so that the appearance color of the front of the module is consistent, such as achieving a full black effect, which is conducive to the full black design of the back contact module. Also, the transmission distance of the current can be effectively shortened, and the risk of solder ribbon transmission loss and edge cracking can be reduced.

[0087] (Five) the auxiliary solder ribbon 500, the auxiliary solder ribbon 500 is arranged on the side of the bus bar 400 away from the cell sheet, the auxiliary solder ribbon 500 is electrically connected with the bus bar 400, and the auxiliary solder ribbon 500 is electrically connected with one of the first main solder ribbon 200 and the second main solder ribbon 200.

[0088] In some embodiments, the material of the auxiliary solder ribbon 500 is the same as the material of the main solder ribbon 200, which can be a tin-plated copper ribbon or a tin-coated copper ribbon.

[0089] In some embodiments, the insulating layer 300 covers the main solder strip 200, the contact points of the main solder strip 200 with the edges of the insulating layer 300 include a first contact point and a second contact point; the auxiliary solder strip 500 crosses the insulating layer 300 along the extension direction of the main solder strip 200 and is in electrical contact with the first contact point and the second contact point, respectively. In some embodiments, one end of the auxiliary solder strip 500 is beyond the first contact point; or, the other end of the auxiliary solder strip 500 is beyond the second contact point; or, one end of the auxiliary solder strip 500 is beyond the first contact point and the other end of the auxiliary solder strip 500 is beyond the second contact point.

[0090] In some embodiments, the auxiliary solder strip 500 includes a first auxiliary solder strip 500 and a second auxiliary solder strip 500, the first auxiliary solder strip 500 is in electrical connection with the first main solder strip 200, and the second auxiliary solder strip 500 is in electrical connection with the second main solder strip 200; when the first auxiliary solder strip 500 is in electrical connection with the first main solder strip 200, the second auxiliary solder strip 500 is not arranged; or, when the second auxiliary solder strip 500 is in electrical connection with the second main solder strip 200, the first auxiliary solder strip 500 is not arranged.

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

[0092] In some embodiments, the auxiliary solder strip is in electrical connection with the bus bar 400 by welding; the auxiliary solder strip is in electrical connection with the first main solder strip 200 by welding; and the auxiliary solder strip is in electrical connection with the second main solder strip 200 by welding. That is, in some embodiments, the main solder strip 200 and the battery piece are welded by welding, and the main solder strip 200, the bus bar 400 and the auxiliary solder strip 500 are electrically connected by welding, which avoids other complex manufacturing processes such as hole opening on the insulating layer 300, which is conducive to automatic production and has low requirements for automation precision, thereby improving the production yield.

[0093] In summary, the back contact assembly provided by the present disclosure is provided with a first doped region and a second doped region on the back of the battery piece, a first grid line on the first doped region, and a second grid line on the second doped region. By arranging the first main solder strip 200 electrically connected with the first grid line and the second main solder strip 200 electrically connected with the second grid line, the current of the first fine grid and the second fine grid can be conducted by the first main solder strip 200 and the second main solder strip 200.

[0094] And, the insulating layer 300 is arranged on the side of the main welding strip 200 away from the battery sheet, 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 separates the bus bar 400 and the main welding strip 200, prevents the bus bar 400 from being connected with the welding strip of the opposite polarity, and prevents the battery sheet from being short-circuited; meanwhile, the welding strip can be completely attached to the electrode area by additionally arranging the insulating layer 300, the welding strip can be connected with a sufficient number of fine grids, each fine grid on the battery sheet is fully utilized, the current is better collected, and the current collection effect is improved.

[0095] Furthermore, the bus bar 400 is arranged on the side of the insulating layer 300 away from the battery sheet, the bus bar 400 is used for collecting the current on the welding strip of the same polarity, and further, when the bus bar 400 is hidden on the back contact assembly, the current collection effect can be effectively improved by arranging the main welding strip 200 and the insulating layer 300.

[0096] Further, the auxiliary welding strip 500 is arranged on the side of the bus bar 400 away from the battery sheet, the auxiliary welding strip 500 is electrically connected with the bus bar 400, and the auxiliary welding strip 500 is electrically connected with one of the first main welding strip 200 and the second main welding strip 200. By increasing the auxiliary welding strip 500, the bus bar 400 can be electrically connected with the welding strip of the same polarity without a complex process.

[0097] Correspondingly, the disclosure provides a preparation method of a back contact assembly, as shown in FIG. 2, comprising the following steps:

[0098] Placing a plurality of battery sheets on the combination of the front plate and the front adhesive film, the back surface of the battery sheet having a first doped area and a second doped area, the first doped area being provided with a first grid line, and the second doped area being provided with a second grid line;

[0099] The battery sheets are connected in series by the main welding strip 200 to form a battery string 100, the main welding strip 200 comprising a first main welding strip 200 and a second main welding strip 200, the first main welding strip 200 being electrically connected with the first grid line, and the second main welding strip 200 being electrically connected with the second grid line;

[0100] The insulating layer 300 is arranged on the main welding strip 200, the insulating layer 300 being located on the side of the main welding strip 200 away from the battery sheet, the insulating layer 300 insulating the bus bar 400 from the first main welding strip 200 and the second main welding strip 200; the bus bar 400 is arranged on the insulating layer 300, the bus bar 400 being arranged on the side of the insulating layer 300 away from the battery sheet; the auxiliary welding strip 500 is arranged on the bus bar 400, the auxiliary welding strip 500 being arranged on the side of the bus bar 400 away from the battery sheet, the auxiliary welding strip 500 being electrically connected with the bus bar 400, and the auxiliary welding strip 500 being electrically connected with one of the first main welding strip 200 and the second main welding strip 200, to form a semi-finished product; or,

[0101] Place the insulating layer, the busbar and the sub-welding strip assembly on the main welding strip, the assembly is located on the side of the main welding strip away from the battery sheet, the insulating layer insulates the busbar from the first main welding strip and the second main welding strip, the busbar and the sub-welding strip are sequentially arranged on the insulating layer, the sub-welding strip is electrically connected with the busbar, and the sub-welding strip is electrically connected with one of the first main welding strip and the second main welding strip, thereby forming a semi-finished product;

[0102] Place the front plate and the front adhesive film on one side of the semi-finished product, and place the back adhesive film and the back plate on the other side of the semi-finished product, thereby forming a to-be-laminated piece, laminating the to-be-laminated piece, and obtaining a finished product.

[0103] In the above preparation method, in some embodiments, the sub-welding strip is electrically connected with the busbar 400 by welding; the sub-welding strip is electrically connected with the first main welding strip 200 by welding; and the sub-welding strip is electrically connected with the second main welding strip 200 by welding. In some embodiments, the first main welding strip 200 is electrically connected with the first grid line by welding; or, the second main welding strip 200 is electrically connected with the second grid line by welding; or, the first main welding strip 200 is electrically connected with the first grid line by welding, and the second main welding strip 200 is electrically connected with the second grid line by welding. That is, in some embodiments, the main welding strip 200 and the battery sheet are welded by welding, and the main welding strip 200, the busbar 400 and the sub-welding strip 500 are electrically connected by welding, avoiding other complex manufacturing processes such as hole opening on the insulating layer 300. This is also conducive to realizing automatic production and does not require high automation precision, thereby improving production yield.

[0104] In addition, in some embodiments, the battery sheet is connected in series by the main welding strip 200 to form a battery string 100, including that the battery string 100 includes at least 3 battery sheets, the first main welding strip 200 electrically connects the first grid lines of two adjacent battery sheets, and the second main welding strip 200 electrically connects the second grid lines of two adjacent battery sheets.

[0105] In some embodiments, the insulating layer 300, the busbar 400 and the sub-welding strip 500 assembly are prepared by the following method:

[0106] Place the busbar 400 on the insulating layer 300 to obtain an assembly semi-finished product; and place the sub-welding strip 500 on a preset position of the assembly semi-finished product to obtain an assembly. In some embodiments, the preset position includes a first preset position and a second preset position; place the first sub-welding strip 500 on the first preset position of the assembly semi-finished product, so that the first sub-welding strip 500 is electrically connected with the first main welding strip 200, thereby obtaining a first assembly; or, place the second sub-welding strip 500 on the second preset position of the assembly semi-finished product, so that the second sub-welding strip 500 is electrically connected with the second main welding strip 200, thereby obtaining a second assembly.

[0107] In some embodiments, a front plate, such as a photovoltaic glass, can be covered on the adhesive film on the front of the cell piece, the front plate can be super white glass, which has high light transmittance, high transparency, and has superior physical, mechanical and optical properties, for example, the light transmittance of super white glass can reach more than 92%, which can protect the cell piece without affecting the efficiency of the cell piece as much as possible.

[0108] At the same time, the front adhesive film can bond the front plate and the cell piece together, and the presence of the front adhesive film can seal and insulate the cell piece and prevent water and moisture.

[0109] In some embodiments, the back plate can be attached to the adhesive film on the back of the cell piece, the back plate can protect and support the cell piece, has reliable insulation, water resistance and aging resistance, the back plate can have multiple choices, which can be usually tempered glass, organic glass, aluminum alloy TPT composite adhesive film, KPC, CPC, etc., which can be set according to specific circumstances, which is not limited here. The whole composed of the back plate, the cell piece, the adhesive film and the front plate can be set on the metal frame, the metal frame as the main external supporting structure of the whole back contact assembly, and can stably support and install the back contact assembly, for example, the back contact assembly can be installed at the position required to be installed through the metal frame.

[0110] At the same time, the back adhesive film can bond the light back plate and the cell piece together, and the presence of the adhesive film can seal and insulate the cell piece and prevent water and moisture.

[0111] Further, the present disclosure also provides a photovoltaic power generation system 1 comprising the back contact assembly or the back contact assembly prepared by the preparation method of the back contact assembly above. The photovoltaic power generation system 1 can be applied in photovoltaic power stations, such as ground power stations, roof power stations, water surface power stations, etc., and can also be applied in devices or apparatuses that utilize solar energy to generate electricity, such as user solar power sources, solar street lamps, 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 to say, the photovoltaic power generation system 1 can be applied in all fields that need to use solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic power generation system 1 can comprise a photovoltaic array, a combiner box and an inverter, the photovoltaic array can be an array combination of a plurality of cell assemblies 10, for example, a plurality of cell assemblies 10 can form a plurality of photovoltaic arrays, the photovoltaic arrays are connected to the combiner box, the combiner box can combine the current generated by the photovoltaic arrays, the combined current flows through the inverter to convert into alternating current required by the power grid, and then is connected to the power grid to realize solar power supply.

[0112] In the description of the disclosure, the description of the terms "some embodiments", "exemplary embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least some embodiments or examples of the disclosure. In the description of the disclosure, the exemplary description 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 appropriate manner in one or more embodiments or examples.

[0113] The above disclosure is only a preferred embodiment of the disclosure, and of course cannot be used to limit the scope of the disclosure. Therefore, equivalent changes made in accordance with the claims of the disclosure are still within the scope of the disclosure.

Claims

1. A back contact module, comprising: a battery string, the battery string comprising at least two battery pieces connected in series, each of the battery pieces comprising a first doped region and a second doped region on a back surface of the battery piece, the first doped region having a first busbar disposed thereon, and the second doped region having a second busbar disposed thereon; a main busbar, the main busbar comprising a first main busbar and a second main busbar, the first main busbar being electrically connected to the first busbar, and the second main busbar being electrically connected to the second busbar; an insulating layer, the insulating layer being disposed on a side of the main busbar facing away from the battery piece; a busbar, the busbar being disposed on a side of the insulating layer facing away from the battery piece, the insulating layer insulating the busbar from the first main busbar and the second main busbar; a sub busbar, the sub busbar being disposed on a side of the busbar facing away from the battery piece, the sub busbar being electrically connected to the busbar, and the sub busbar being electrically connected to one of the first main busbar and the second main busbar.

2. The back contact assembly of claim 1, wherein, the insulating layer covers the main busbar, and a contact point of the main busbar with an edge of the insulating layer comprises a first contact point and a second contact point; the sub busbar crosses the insulating layer in an extension direction of the main busbar, and is electrically connected to the first contact point and the second contact point, respectively.

3. The back contact assembly of claim 2, wherein, one end of the sub busbar is beyond the first contact point; or, the other end of the sub busbar is beyond the second contact point; or, one end of the sub busbar is beyond the first contact point, and the other end of the sub busbar is beyond the second contact point.

4. The back contact assembly of claim 1, wherein, the sub busbar comprises a first sub busbar and a second sub busbar, the first sub busbar being electrically connected to the first main busbar, and the second sub busbar being electrically connected to the second main busbar.

5. The back contact assembly of claim 4, wherein, when the first sub busbar is electrically connected to the first main busbar, the second sub busbar is not provided; or, when the second sub busbar is electrically connected to the second main busbar, the first sub busbar is not provided.

6. The back contact assembly of claim 1, wherein, the main busbar and the sub busbar extend in a second direction, and the insulating layer and the busbar extend in a first direction, the first direction and the second direction intersecting.

7. The back contact assembly of claim 1, wherein, a width of the insulating layer is greater than or equal to a width of the busbar.

8. The back contact assembly of claim 1, wherein, in a series direction of the battery pieces in the battery string, the insulating layer and the busbar are located in a middle region of the battery pieces at end positions in the battery string.

9. The back contact assembly of claim 1, wherein, the insulating layer is black, white or transparent.

10. The back contact assembly of claim 1, wherein, the battery piece is a main busbar-free battery piece.

11. The back contact assembly of claim 1, wherein, the sub busbar is electrically connected to the busbar by welding.

12. The back contact assembly of claim 1, wherein, the sub busbar is electrically connected to the first main busbar by welding.

13. The back contact assembly of claim 1, wherein, the sub busbar is electrically connected to the second main busbar by welding. 14.A method for manufacturing the back contact module according to any one of claims 1 to 13, comprising the following steps: placing a plurality of battery pieces on a combination of a front plate and a front adhesive film, the battery pieces having a first doped region and a second doped region on a back surface of the battery piece, the first doped region having a first busbar disposed thereon, and the second doped region having a second busbar disposed thereon; The battery pieces are connected in series by main welding strips, the main welding strips include first main welding strips and second main welding strips, the first main welding strips are electrically connected with the first grid lines, and the second main welding strips are electrically connected with the second grid lines; An insulating layer is arranged on the main welding strips, the insulating layer is arranged on a side of the main welding strips away from the battery pieces, the insulating layer insulates the bus bar from the first main welding strips and the second main welding strips; a bus bar is arranged on the insulating layer, the bus bar is arranged on a side of the insulating layer away from the battery pieces; a sub welding strip is arranged on the bus bar, the sub welding strip is arranged on a side of the bus bar away from the battery pieces, the sub welding strip is electrically connected with the bus bar, and the sub welding strip is electrically connected with one of the first main welding strips and the second main welding strips, to form a semi-finished product; or, An insulating layer, a bus bar and a sub welding strip assembly are arranged on the main welding strips, the assembly is arranged on a side of the main welding strips away from the battery pieces, the insulating layer insulates the bus bar from the first main welding strips and the second main welding strips, the bus bar and the sub welding strip are sequentially arranged on the insulating layer, the sub welding strip is electrically connected with the bus bar, and the sub welding strip is electrically connected with one of the first main welding strips and the second main welding strips, to form the semi-finished product; A front plate and a front adhesive film are arranged on one side of the semi-finished product, and a back adhesive film and a back plate are arranged on the other side of the semi-finished product, to form a to-be-laminated piece, the to-be-laminated piece is laminated, and a finished product is obtained.

15. The method of making a back contact assembly of claim 14, wherein, The sub welding strip is electrically connected with the bus bar by welding.

16. The method of making a back contact assembly of claim 14, wherein, The sub welding strip is electrically connected with the first main welding strip by welding.

17. The method of making a back contact assembly of claim 14, wherein, The sub welding strip is electrically connected with the second main welding strip by welding.

18. The method of making a back contact assembly of claim 14, wherein, The battery pieces are connected in series by main welding strips, including: The battery string includes at least three battery pieces, the first main welding strips electrically connect the first grid lines of two adjacent battery pieces, and the second main welding strips electrically connect the second grid lines of two adjacent battery pieces.

19. The method of making a back contact assembly of claim 18, wherein, The first main welding strips are electrically connected with the first grid lines by welding; or the second main welding strips are electrically connected with the second grid lines by welding; or the first main welding strips are electrically connected with the first grid lines by welding, and the second main welding strips are electrically connected with the second grid lines by welding.

20. The method of making a back contact assembly of claim 14, wherein, The insulating layer, the bus bar and the sub welding strip assembly are obtained by the following method: A bus bar is arranged on an insulating layer, to obtain an assembly semi-finished product; A sub welding strip is arranged on a preset position of the assembly semi-finished product, to obtain an assembly.

21. The method of making a back contact assembly of claim 20, wherein, The preset position includes a first preset position and a second preset position; A first sub welding strip is arranged on the first preset position of the assembly semi-finished product, so that the first sub welding strip is electrically connected with the first main welding strip, to obtain a first assembly; Or, a second sub welding strip is arranged on the second preset position of the assembly semi-finished product, so that the second sub welding strip is electrically connected with the second main welding strip, to obtain a second assembly.

22. A photovoltaic power system comprising a back contact module according to any one of claims 1 to 13 or a back contact module prepared according to the method of any one of claims 14 to 21.

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