Back contact cell assembly, preparation method therefor, and photovoltaic system

Abstract

The present disclosure provides a back contact cell assembly, a preparation method therefor, and a photovoltaic system. A first doped layer and a second doped layer each extending in a first direction are disposed on a back surface of a cell of the assembly. A solder ribbon extending in a third direction is separately electrically connected to the first doped layer of the cell and the second doped layer of an adjacent cell. An included angle between the first direction and the third direction is an acute angle.

Description

Back contact cell assembly, preparation method thereof and photovoltaic system

[0001] Cross-reference to related applications

[0002] The present disclosure claims priority to the Chinese patent application No. 202411077547.1, filed on August 5, 2024, entitled "Back contact cell assembly, preparation method thereof and photovoltaic system", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure belongs to the technical field of solar cells, and particularly relates to a back contact cell assembly, a preparation method thereof and a photovoltaic system. BACKGROUND

[0004] At present, the back contact cell refers to a solar cell in which no electrode is arranged on the light-receiving surface of a cell piece, and the positive and negative electrodes are arranged on the back light side of the cell piece, so that the electrode can reduce the shading of the cell piece, increase the short-circuit current of the cell piece, and improve the energy conversion efficiency of the cell piece. However, in the prior art, the electrodes and the solder strip of the back contact cell are arranged on the back surface of the cell piece. Due to thermal expansion and contraction, the solder strip will displace relative to the cell piece, which can cause the solder strip to break or separate from the cell piece. SUMMARY

[0005] The present disclosure provides a back contact cell assembly, a preparation method thereof and a photovoltaic system, which aims to solve the problem that the solder strip is easily separated from the cell piece during use of the photovoltaic cell.

[0006] The back contact cell assembly provided by the present disclosure includes a cell string and a solder strip. The cell string includes a plurality of cell pieces. The cell piece has opposite front and back surfaces. The back surface is provided with a first doped layer and a second doped layer. The first doped layer and the second doped layer extend along a first direction and are alternately distributed along a second direction. The first direction and the second direction intersect. The solder strip is arranged on at least two cell pieces and electrically connected to the first doped layer of the cell piece and the second doped layer of the adjacent cell piece, respectively. The solder strip extends along a third direction and is alternately distributed along the second direction. The included angle between the first direction and the third direction is an acute angle. The doping polarities of the first doped layer and the second doped layer are opposite.

[0007] In some embodiments, the included angle α between the first direction and the third direction satisfies the following relationship: 0 < tan α ≤ D / L.

[0008] L is the total length of the first and last cell in the battery string in the first direction, and D is the width of any one doped layer of the cell in the second direction.

[0009] In some embodiments, the first doped layer and the second doped layer have equal width in the second direction.

[0010] In some embodiments, the center distance of two adjacent solder strips in the second direction is equal.

[0011] The center distance of two adjacent doped layers is equal.

[0012] The center distance of two adjacent doped layers is equal to the center distance of two adjacent solder strips.

[0013] In some embodiments, the back surface is provided with a first grid line and a second grid line, the first grid line and the second grid line extend in the first direction and are alternately distributed in the second direction, the first grid line is arranged on the first doped layer, the second grid line is arranged on the second doped layer, and the solder strip covers the first grid line of the cell and the second grid line of the adjacent cell.

[0014] In some embodiments, the center distance of two adjacent grid lines is equal.

[0015] The center distance of two adjacent grid lines is equal to the center distance of two adjacent solder strips.

[0016] In some embodiments, a plurality of solder strips are arranged in parallel.

[0017] The first grid line, the second grid line, the first doped layer and the second doped layer are arranged in parallel.

[0018] In some embodiments, the solder strip includes a first side and a second side, both of which extend in the third direction, and on any cell, the first side includes a starting segment and a tail segment, and the distance between the grid line and the starting segment is greater than the distance between the grid line and the tail segment.

[0019] In some embodiments, the cell is rectangular, and the cell includes a first cell and a second cell arranged in the first direction, and the cell includes a first edge and a second edge distributed in the second direction, the first edge closest to the first grid line of the first cell is the first grid line, and the second edge closest to the second grid line of the second cell is the second grid line.

[0020] In some embodiments, the solder strip is in a long strip shape, and a width of the solder strip is less than a pitch between the first and second grid lines.

[0021] In some embodiments, the solder strip includes a first solder strip and a second solder strip, the first and second solder strips extend along the third direction and are alternately distributed along a second direction.

[0022] The first solder strip covers and connects the first doped layer of the first cell or the first grid line and the second doped layer of the second cell or the second grid line.

[0023] The second solder strip covers and connects the second doped layer of the first cell or the second grid line and the first doped layer of another second cell or the first grid line.

[0024] In some embodiments, a distance between the starting segment and the first edge of the cell is less than a distance between the tail segment and the first edge of the cell.

[0025] In some embodiments, the first edge of the cell is parallel to the doped layer or the grid line.

[0026] The present disclosure provides a preparation method of a back contact cell assembly, the preparation method comprising:

[0027] Placing a plurality of cells along a first direction to form an array of cell strings;

[0028] Laying a solder strip along a third direction on a back surface of the cell, the solder strip being in a strip shape to at least partially cover a doped layer of the cell or a grid line disposed on the doped layer, wherein an included angle between the first direction and the third direction is an acute angle;

[0029] The solder strip is disconnected at a predetermined position;

[0030] Placing an adhesive film and a back plate on a side of the cell provided with the solder strip to form a to-be-laminated piece;

[0031] Framing and installing the to-be-laminated piece, and welding a junction box to form a back contact cell assembly.

[0032] The photovoltaic system provided by the present disclosure includes the back contact cell assembly according to any one of the above embodiments.

[0033] In the back contact battery assembly of the embodiment of the present disclosure, the back contact battery assembly comprises a battery string and a solder strip, the battery string comprises a plurality of battery pieces, the battery piece has opposite front and back surfaces, the back surface is provided with a first doped layer and a second doped layer, the first doped layer and the second doped layer extend along a first direction and are alternately distributed along a second direction, wherein the first direction and the second direction intersect, the solder strip is arranged on at least two battery pieces and respectively electrically connects the first doped layer of the battery piece and the second doped layer of the adjacent battery piece, the solder strip extends along a third direction and is alternately distributed along the second direction, wherein the included angle between the first direction and the third direction is an acute angle, and the doping polarities of the first doped layer and the second doped layer are opposite. In this way, the solder strip can be arranged to be inclined to the doped layer at an acute angle, so as to increase the contact area of the solder strip and the battery piece, thereby increasing the electrical contact area of the solder strip and the doped layer and improving the conduction efficiency of the doped layer to the solder strip. At the same time, the inclined arrangement of the solder strip can relieve the problem of stress concentration, so as to ensure the stable connection of the solder strip and the battery piece. BRIEF DESCRIPTION OF DRAWINGS

[0034] FIG. 1 is a schematic diagram of a partial planar structure of a back contact battery assembly according to an embodiment of the present disclosure;

[0035] FIG. 2 is another schematic diagram of a partial planar structure of a back contact battery assembly according to an embodiment of the present disclosure;

[0036] FIG. 3 is a schematic diagram of a module structure of a back contact battery assembly according to an embodiment of the present disclosure;

[0037] FIG. 4 is still another schematic diagram of a partial planar structure of a back contact battery assembly according to an embodiment of the present disclosure;

[0038] FIG. 5 is yet another schematic diagram of a partial planar structure of a back contact battery assembly according to an embodiment of the present disclosure;

[0039] FIG. 6 is a flowchart of a preparation method of a back contact battery assembly according to an embodiment of the present disclosure;

[0040] FIG. 7 is a schematic diagram of a photovoltaic system according to an embodiment of the present disclosure.

[0041] Main element symbol explanation: back contact battery assembly 100, back surface 12, first grid line 121, second grid line 122, first doped layer 123, second doped layer 124, first edge 13, second edge 14, first battery piece 101, second battery piece 102, first solder strip 21, second solder strip 22, first side 23, starting section 231, tail section 232, second side 24, battery string 200, photovoltaic system 300. DETAILED DESCRIPTION

[0042] In order to make the objects, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below with reference to the drawings and embodiments. The examples of the embodiments are shown in the drawings, wherein the same or similar notations denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only, and are only used to explain the present disclosure, and cannot be understood as limitations to the present disclosure. In addition, it should be understood that the specific embodiments described herein are only used to explain the present disclosure, and are not used to limit the present disclosure.

[0043] 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 based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present disclosure and simplifying 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 to the present disclosure.

[0044] 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 the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present disclosure, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0045] In the description of the present disclosure, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, or 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.

[0046] In the present disclosure, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the 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 "upper", "above" and "on" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "below", "under" and "under" of the first feature to the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0047] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present disclosure. For the purpose of simplicity, the elements and settings of particular examples in the following are described. Of course, they are merely examples and are not intended to limit the present disclosure. Furthermore, the present disclosure can repeat reference numerals and / or letters in various examples and / or throughout the specification. This repetition is for the purpose of simplicity and clarity and is not in itself a limitation of the various embodiments and / or settings discussed in the present disclosure. Also, the various embodiments of the present disclosure provide examples of various processes and materials. However, one skilled in the art will appreciate that other processes and / or materials can be used.

[0048] In the related art, a solar cell is a semiconductor device that directly converts the energy of sunlight into electricity. The solar cell utilizes the photovoltaic effect to excite electrons by absorbing photons and to guide these electrons to generate electric current by the built-in electric field. The back contact cell refers to a solar cell in which the light-receiving surface of the cell sheet is free of electrodes, and the positive and negative electrodes are arranged on the back light side of the cell sheet, so that the shading of the cell sheet by the electrodes can be reduced, the short-circuit current of the cell sheet can be increased, and the energy conversion efficiency of the cell sheet can be improved. However, in the prior art, the electrodes and the solder strip of the back contact cell are arranged on the back surface of the cell sheet. Due to thermal expansion and contraction, the solder strip will displace relative to the cell sheet, which can cause the solder strip to break or separate from the cell sheet. In the embodiments of the present disclosure, the solder strip can be arranged at an acute angle with the doped layer to increase the contact area between the solder strip and the cell sheet, thereby increasing the electrical contact area between the solder strip and the doped layer and improving the electrical conductivity efficiency of the doped layer to the solder strip. At the same time, the inclined arrangement of the solder strip can alleviate the problem of stress concentration to ensure stable connection between the solder strip and the cell sheet.

[0049] Embodiment one

[0050] Referring to FIGS. 1, 2 and 3, a back contact cell assembly 100 provided by the present disclosure includes a cell string 200 and a solder strip (not labeled in the figure), and the cell string 200 includes a plurality of cell sheets (not labeled in the figure). The cell sheet has opposite front and back surfaces 12, and the back surface 12 is provided with a first doped layer 123 and a second doped layer 124. The first doped layer 123 and the second doped layer 124 extend along a first direction and are alternately distributed along a second direction, wherein the first direction and the second direction intersect. The solder strip is arranged on at least two cell sheets and electrically connected to the first doped layer 123 of the cell sheet and the second doped layer 124 of the adjacent cell sheet, respectively. The solder strip extends along a third direction and is alternately distributed along the second direction, wherein the included angle between the first direction and the third direction is an acute angle, and the doping polarity of the first doped layer 123 and the second doped layer 124 is opposite.

[0051] As shown in FIGS. 1 and 2, in some optional embodiments, the cell sheet includes a first cell sheet 101 and a second cell sheet 102 arranged in sequence along the first direction.

[0052] As shown in FIG. 2, in some optional embodiments, the back surface of the cell sheet is provided with grid lines, the grid lines include first grid lines 121 and second grid lines 122, the first grid lines 121 are arranged on the first doped layer 123, the second grid lines 122 are arranged on the second doped layer 124, and the first grid lines 121 and the second grid lines 122 extend along the first direction and are alternately distributed along the second direction.

[0053] As shown in FIG. 2, in some optional embodiments, the solder strip includes first solder strips 21 and second solder strips 22, the first solder strips 21 and the second solder strips 22 extend along the third direction and are alternately distributed along the second direction.

[0054] In the back contact battery assembly 100 of the embodiment of the present disclosure, the back contact battery assembly 100 includes a cell string 200 and a solder strip, the cell string 200 includes a plurality of cell sheets, the cell sheet has opposite front and back surfaces 12, the back surface 12 is provided with a first doped layer 123 and a second doped layer 124, the first doped layer 123 and the second doped layer 124 extend along the first direction and are alternately distributed along the second direction, wherein the first direction and the second direction intersect, the solder strip is arranged on at least two cell sheets and respectively electrically connects the first doped layer 123 of the cell sheet and the second doped layer 124 of the adjacent cell sheet, the solder strip extends along the third direction and is alternately distributed along the second direction, wherein the included angle between the first direction and the third direction is an acute angle, and the doping polarities of the first doped layer 123 and the second doped layer 124 are opposite. In this way, the solder strip can be arranged to be inclined to the doped layer at an acute angle, so as to increase the contact area of the solder strip and the cell sheet, thereby increasing the electrical contact area of the solder strip and the doped layer and improving the conduction efficiency of the doped layer to the solder strip. At the same time, the inclined arrangement of the solder strip can relieve the problem of stress concentration, so as to ensure the stable connection of the solder strip and the cell sheet and improve the connection stability of the solder strip and the cell sheet.

[0055] In the present embodiment, the front surface of the cell sheet is used to receive light, and the back surface 12 of the cell sheet includes a plurality of alternately arranged first doped layers 123 and second doped layers 124, the first doped layers 123 and the second doped layers 124 both extend along the first direction to form a photoelectric current.

[0056] Specifically, the first doped layer 123 of the cell sheet and the second doped layer 124 of the adjacent cell sheet can be connected together by the solder strip, and the second doped layer 124 of the cell sheet and the first doped layer 123 of another adjacent cell sheet can be connected together by the solder strip. That is, a plurality of cell sheets can be connected together by the solder strip to form a cell string 200 distributed along the first direction. Of course, in some embodiments, the solder strip located at the end of the cell string 200 can only connect one doped layer and extend relative to the cell sheet to connect a bus bar or the like structure.

[0057] It can be understood that in the battery string 200, the battery string 200 can include two battery pieces in series, three battery pieces in series, or other more number of battery pieces, and the number of battery pieces to be connected in series can be determined according to actual use. In addition, in the embodiments of the present disclosure, the size and type of the battery piece are not limited, and the specifications and sizes of adjacent battery pieces can be the same or different to meet different needs.

[0058] In the embodiments of the present disclosure, the specific arrangement of adjacent battery pieces is not limited to meet different needs. In one embodiment, the edges of two adjacent battery pieces are at least partially stacked together; in another embodiment, two adjacent battery pieces can be spaced apart. The spacing between two adjacent battery pieces is within a suitable range, which can avoid small operating space and difficult welding caused by small spacing, and can also avoid wasting component space and increasing cost caused by large spacing.

[0059] In the embodiments of the present disclosure, the doping type of the first doped layer 123 and the second doped layer 124 is not limited, for example, the first doped layer 123 and the second doped layer 124 can be a P-type doped layer and an N-type doped layer, respectively; or the first doped layer 123 can be an N-type doped layer and the second doped layer 124 can be a P-type doped layer, as long as the polarity of the two is opposite to meet different needs. In some embodiments, the first doped layer 123 can be a P-type polysilicon layer, a P-type amorphous silicon layer, or a P-type microcrystalline silicon layer, which is not limited here. Similarly, the second doped layer 124 can be an N-type polysilicon layer, an N-type amorphous silicon layer, or an N-type microcrystalline silicon layer, which is not limited here. When the first doped layer 123 is a P-type doped layer and the second doped layer 124 is an N-type doped layer, a P-type gate line can be further provided on the first doped layer 123, and an N-type gate line can be further provided on the second doped layer 124, which is not limited here.

[0060] In some embodiments, P-type doping refers to doping group III elements, including boron, aluminum, gallium, indium, thallium, and the like; N-type doping refers to doping group V elements, including nitrogen, phosphorus, arsenic, antimony, bismuth, and the like, which is not limited here.

[0061] In addition, in some embodiments, the first doped layer 123 and the second doped layer 124 can also be a composite type of doping, for example, N-type doping also includes a small amount of P-type doping elements. Among them, the content of N-type doping elements of the second doped layer 124 is higher than 20% of the content of P-type doping elements to ensure that the polarity of the first doped layer 123 is opposite.

[0062] In the back contact battery assembly 100 of the embodiments of the present disclosure, the first direction and the second direction can be perpendicular directions, at this time, the battery piece can be rectangular, and the first direction and the second direction are also edge directions of the battery piece, so as to maximize the use of the area of the battery piece. The solder strip is arranged on at least two battery pieces in the third direction, and electrically connected to the first doped layer 123 of the battery piece and the second doped layer 124 of the adjacent battery piece, respectively. The solder strip is alternately distributed in the second direction to connect the opposite doped layers of the adjacent battery pieces to form the battery string 200, wherein the included angle between the first direction and the third direction is an acute angle. By arranging the solder strip to be inclined at an acute angle with the doped layer, the contact area of the solder strip with the battery piece is significantly increased, thereby increasing the electrical contact area of the solder strip with the doped layer and enhancing the conduction efficiency. At the same time, the inclined design of the solder strip can effectively alleviate the stress concentration problem, ensure the stability of the connection between the solder strip and the battery piece, and reduce the connection failure caused by mechanical stress or temperature change. The firm connection between the solder strip and the doped layer ensures the stable electrical connection between the battery pieces, and improves the reliability and service life of the back contact battery assembly 100.

[0063] In the back contact battery assembly 100 of the embodiments of the present disclosure, the solder strip is actively arranged to be inclined at an acute angle with the doped layer, which can reduce the process difficulty of the back contact battery assembly 100, reduce the alignment requirement in the welding process, improve the fault tolerance and precision of welding, and reduce the manufacturing complexity. The inclined arrangement mode is easier to operate by automatic equipment, improves the production efficiency, reduces manual intervention, and reduces the production cost. The acute-angled and inclined design of the solder strip helps to disperse mechanical stress, reduce stress concentration at the welding point, and improve the reliability and durability of the welding point.

[0064] In the embodiments of the present disclosure, the type of the battery piece is not limited to meet different needs. For example, the battery piece can be a type without grid lines, and the current conduction is realized by direct connection between the solder strip and the doped layer. In addition, in the embodiments of the present disclosure, the width of the doped layer of the battery piece in the second direction is equal.

[0065] It can be understood that in such embodiments, the back contact battery assembly 100 can further include a frame, a back plate, photovoltaic glass and a film. The film can be filled between the front surface and the back surface 12 of the battery piece, the photovoltaic glass, the adjacent battery piece and the like, and can be a transparent adhesive with good light transmission performance and aging resistance, for example, the film can use EVA film or POE film, which can be selected according to actual conditions, and is not limited herein.

[0066] The photovoltaic glass can be covered on the adhesive film on the front of the cell piece. The photovoltaic glass 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. At the same time, the adhesive film can bond the photovoltaic glass and the cell piece together, and the presence of the adhesive film can seal and insulate the cell piece and prevent water and moisture.

[0067] The back plate can be attached to the adhesive film on the back of the cell piece 12. 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 usually be tempered glass, organic glass, aluminum alloy TPT composite adhesive film, etc. The specific setting can be made according to the specific situation, which is not limited here. The whole composed of the back plate, the cell piece, the adhesive film and the photovoltaic glass can be set on the frame. The frame is the main external support structure of the whole back contact battery assembly 100, and can stably support and install the back contact battery assembly 100. For example, the back contact battery assembly 100 can be installed at the required installation position through the frame.

[0068] Embodiment two

[0069] Please refer to FIG. 1 and FIG. 2. In some optional embodiments, the included angle α between the first direction and the third direction satisfies the following relationship: 0 < tan α ≤ D / L.

[0070] Wherein, L is the total length of the first cell piece and the last cell piece in the cell string 200 along the first direction, and D is the width of any one doped layer of the cell piece along the second direction.

[0071] In this way, the inclination angle of the welding strip can be obtained according to the length of the cell string 200, and the angle can be adjusted for cell strings 200 of different lengths and different types, so that one welding strip can completely cover the doped layers on the same straight line of multiple cell pieces. In this way, the process can be facilitated, and after the welding strip is connected in series with multiple cell pieces, laser is used for selective cutting to form cell strings 200 in pairs.

[0072] Specifically, according to the length of the cell string 200 and the width of the doped layer, the inclination angle of the welding strip is flexibly adjusted to adapt to the specific needs of different cell strings 200, and to ensure that the welding strip can completely cover the doped layer. Then, by accurately calculating the included angle α, the welding strip can extend along a straight line when covering the doped layer, improving the efficiency and consistency of welding. One welding strip can completely cover the doped layers of multiple cell pieces on the process production line, simplifying the welding process, reducing the welding steps, and improving the production efficiency. After the welding strip is connected in series with multiple cell pieces, laser is used for selective cutting to form cell strings 200 in pairs. This method is efficient and accurate, and reduces the complexity in the production process.

[0073] For example, the battery string 200 can be uniformly distributed with 9 battery pieces along the first direction, and L is the distance between the farthest ends of the 9 battery pieces. According to the length and the width of the doped layer in the second direction, the inclination angle a is calculated so that the solder strip can be arranged at an angle of a.

[0074] In the embodiments of the present disclosure, the range of the included angle between the first direction and the third direction is not limited to meet different needs. In this way, the length of the different battery string 200 and the width of the doped layer in the second direction can be adjusted.

[0075] Furthermore, the width of the first doped layer 123 and the second doped layer 124 in the second direction is equal. In this way, the first doped layer 123 and the second doped layer 124 can be distributed, and the solder strip can be uniformly arranged on the back surface 12, so that the solder strip can be arranged on the corresponding doped layer after being disconnected. The doped layer can be uniformly distributed, and the solder strip can be uniformly covered on the back surface 12 to ensure uniform current output.

[0076] Furthermore, in the second direction, the center distance of the adjacent two solder strips is equal;

[0077] The center distance of the adjacent two doped layers is equal;

[0078] The center distance of the adjacent two doped layers is equal to the center distance of the adjacent two solder strips.

[0079] In this way, after the doped layer is uniformly distributed on the back surface 12 of the battery piece, the solder strip can also be uniformly arranged on the back surface 12 of the battery piece, and the center distance between the adjacent solder strips is equal to the center distance between the adjacent doped layers, so that the solder strip and the doped layer can be accurately arranged, and each doped layer can effectively connect the solder strip.

[0080] In the embodiments of the present disclosure, the center distance of the adjacent two solder strips is not limited to meet different needs. For example, the center distance of the adjacent two solder strips can be greater than or equal to 100 μm, and preferably, the center distance of the adjacent two solder strips can be 300 μm.

[0081] Embodiment three

[0082] Please refer to FIG. 3 and FIG. 4, in some optional embodiments, the back surface 12 is provided with a first grid line 121 and a second grid line 122, the first grid line 121 and the second grid line 122 extend along the first direction and are alternately distributed along the second direction, the first grid line 121 is arranged on the first doped layer 123, the second grid line 122 is arranged on the second doped layer 124, and the solder strip (not marked in the figure) covers the first grid line 121 of the battery piece (not marked in the figure) and the second grid line 122 of the adjacent battery piece.

[0083] Thus, the first doped layer 123 and the second doped layer 124 can be guided out of current by the first grid line 121 and the second grid line 122, so that the current can be converged and conducted by the solder ribbon.

[0084] Specifically, the first grid line 121 and the second grid line 122 are alternately distributed on the back surface 12 of the cell sheet, ensuring the uniformity of current collection and conduction, and reducing current loss. The first grid line 121 is independently arranged on the first doped layer 123, and the second grid line 122 is independently arranged on the second doped layer 124, avoiding the interference of the grid lines on the same doped layer, and improving the efficiency of current guidance. The solder ribbon covers the first grid line 121 and the second grid line 122 of the adjacent cell sheet, and the current between the multiple cell sheets is converged by the solder ribbon, ensuring efficient conduction of the current.

[0085] Further, in the process preparation of the battery string 200, the solder ribbon can cover the grid lines of multiple cell sheets on the same straight line at one time along the third direction, improving the efficiency of soldering, reducing the soldering steps and time, and being suitable for large-scale production. The design of the solder ribbon attached to the grid line at a certain angle facilitates the operation of the automatic equipment, improves the production precision and consistency. The connection between the solder ribbon and the grid line increases the mechanical strength and stability of the back contact battery assembly 100, prolonging the service life.

[0086] Further, the spacing between the first grid line 121 and the second grid line 122 is flexibly adjusted according to actual needs. The first grid line 121 and the second grid line 122 can be arranged at equal intervals, which can ensure uniform distribution of current and improve the overall efficiency of the back contact battery assembly 100; non-equal interval arrangement can optimize the current conduction path for specific application scenarios, reducing the problem of local overheating or excessive resistance. The combination of part of the equal interval and part of the non-equal interval can combine the advantages of both, flexibly adjust according to specific needs, and optimize the performance of the back contact battery assembly 100.

[0087] Further, the center distance of the adjacent two grid lines is equal;

[0088] The center distance of the adjacent two grid lines is equal to the center distance of the adjacent two solder ribbons. Thus, after the grid lines are uniformly distributed on the back surface 12 of the cell sheet, the solder ribbons can also be uniformly arranged on the back surface 12 of the cell sheet, and the center distance between the adjacent solder ribbons is equal to the center distance between the adjacent grid lines, so that the solder ribbons and the grid lines can be accurately arranged, ensuring that each grid line can effectively connect the solder ribbon.

[0089] In addition, in the embodiments of the present disclosure, the equal center distance means that the distance between the structure centers of two adjacent structures is equal to the distance between the structure centers of another two adjacent structures. The "equal" in the process preparation can be a tolerance ratio of 0.9-1.1, that is, when the rated center distance is 1, the maximum error distance can be 1.1 times of the rated distance, and the minimum error distance can be 0.9 times of the rated distance.

[0090] Further, the plurality of solder strips are arranged in parallel.

[0091] The first gate line 121, the second gate line 122, the first doped layer 123, and the second doped layer 124 are arranged in parallel.

[0092] In this way, the gate lines and the doped layers are arranged in parallel on the back surface 12 of the cell sheet, which can make the cell sheet more regular as a whole. The plurality of solder strips are arranged in parallel on the back surface 12 of the cell sheet and are uniformly distributed in a direction perpendicular to the third direction, ensuring that the distances between the solder strips are consistent and forming a regular layout. Moreover, the solder strips can be arranged correspondingly to the gate lines or the doped layers.

[0093] Embodiment Four

[0094] Referring to FIGS. 4 and 5, in some optional embodiments, the solder strip (not labeled in the figure) includes a first side 23 and a second side 24, both of which extend along the third direction. On any cell sheet (not labeled in the figure), the first side 23 includes a starting section 231 and a tail section 232, and the distance between the gate line and the starting section 231 is greater than the distance between the gate line and the tail section 232.

[0095] In this way, the solder strip is arranged along the third direction on each cell sheet, and the position of the solder strip on the first side 23 of any cell sheet is different from that of the gate line, so that the solder strip can cover the gate line and improve the connection ability with the gate line.

[0096] Specifically, the solder strip is rectangular, and the first side 23 and the second side 24 are arranged along the third direction. The solder strip is arranged along the third direction to ensure that the solder strip covers the gate line, increases the contact area of the solder strip with the gate line, and improves the current conduction efficiency. The distances between the starting section 231 and the tail section 232 of the solder strip and the gate line are different, which ensures the optimal position of the solder strip on the cell sheet and improves the connection ability and stability of the solder strip with the gate line.

[0097] Embodiment Five

[0098] Referring to FIGS. 4 and 5, in some optional embodiments, the battery pieces are rectangular, and the battery pieces include the first battery piece 101 and the second battery piece 102 arranged in sequence along a first direction, the battery pieces include the first edge 13 and the second edge 14 distributed along a second direction, the first battery piece 101 has the first busbar 121 closest to the first edge 13, and the second battery piece 102 has the second busbar 122 closest to the first edge 13; the busbars of the first battery piece 101 and the second battery piece 102 along the first direction are located within the first side 23 and the second side 24.

[0099] In this way, it can be ensured that each busbar is arranged in the solder strip and covered by the solder strip. Meanwhile, the busbars on the same straight line between the adjacent two battery pieces have opposite polarities, so that the solder strip can connect the first battery piece 101 and the second battery piece 102 in series.

[0100] Specifically, the battery pieces are rectangular, which facilitates large-scale production and arrangement and improves space utilization. The battery pieces have the first edge 13 and the second edge 14 distributed along the second direction, which is helpful for reasonable arrangement of the busbars and current collection.

[0101] In the embodiments of the present disclosure, the shape of the battery piece is not limited to meet different needs. For example, the battery piece can be a rectangular or square whole battery piece. Then the square whole battery piece is designed into a corresponding single rectangular battery piece or a single battery piece after cutting (two pieces, three pieces, etc.). The main feature of such a battery piece is that there is no busbar and electrode structure on the front surface, and the positive and negative busbars are distributed on the back surface 12 of the battery piece in sequence and alternately. In addition, in the embodiments of the present disclosure, the number of the first busbar 121 and the second busbar 122, the size range, and the spacing between adjacent busbars are not limited, as long as the busbar can be covered by the solder strip to meet different needs.

[0102] For example, the first busbar 121 can be positive, and the second busbar 122 can be negative. Of course, in other embodiments, they can be opposite, that is, the first busbar 121 can be negative, and the second busbar 122 can be positive, which is not limited here. The alternate distribution of the first busbar 121 and the second busbar 122 and the accurate connection with the solder strip enable the current to be collected and transmitted more effectively, and reduce the fine grid electrical loss.

[0103] In some embodiments, the back contact battery assembly 100 further includes a busbar structure (not shown in the figure), which can connect the solder strips of the same polarity to form a loop with the battery string 200 to guide the current energy out. In the embodiments of the present disclosure, the form of the busbar structure is not limited to meet different needs. For example, the busbar structure can be a wire, a busbar, a conductive tape, or other conductive materials.

[0104] It can be understood that the "first" and "second" in the first cell piece 101 and the second cell piece 102 are relative concepts, which refer to the difference between the two back contact cells. For example, in the example of FIG. 4, the back contact cell on the left is labeled as the first cell piece 101, and the back contact cell on the right is labeled as the second cell piece 102.

[0105] Embodiment six

[0106] Referring to FIGS. 4 and 5, in some optional embodiments, the solder strip is in a long strip shape, and the width of the solder strip is less than the interval between the first grid line 121 and the second grid line 122.

[0107] In this way, when the solder strip is arranged on the cell piece, the problem of short circuit caused by one solder strip simultaneously spanning two grid lines of one cell piece is avoided.

[0108] Specifically, the width of the solder strip is designed to be less than the interval between the first grid line 121 and the second grid line 122, so as to ensure that the solder strip does not simultaneously span and connect two adjacent grid lines when arranged. By controlling the width of the solder strip, the problem of short circuit caused by one solder strip simultaneously spanning two grid lines of one cell piece is avoided, so as to ensure the safe and stable operation of the cell piece.

[0109] Embodiment seven

[0110] Referring to FIGS. 4 and 5, in some optional embodiments, the solder strip includes a first solder strip 21 and a second solder strip 22, the first solder strip 21 and the second solder strip 22 extend along the third direction and are alternately distributed along the second direction;

[0111] The first solder strip 21 covers and connects the first doped layer 123 or the first grid line 121 of the first cell piece 101, and the first solder strip 21 also covers and connects the second doped layer 124 or the second grid line 122 of the second cell piece 102;

[0112] The second solder strip 22 covers and connects the second doped layer 124 or the second grid line 122 of the first cell piece 101, and the second solder strip 22 also covers and connects the first doped layer 123 or the first grid line 121 of another second cell piece 102.

[0113] In this way, the first solder strip 21 and the second solder strip 22 can be sequentially matched to connect the plurality of first cell pieces 101 and the plurality of second cell pieces 102 to form the cell string 200.

[0114] Embodiment eight

[0115] Referring to FIGS. 4 and 5, in some optional embodiments, the distance between the starting segment 231 and the first edge 13 of the cell piece is less than the distance between the tail segment 232 and the first edge 13 of the cell piece.

[0116] Therefore, the welding rib on the battery piece is arranged obliquely relative to the edge of the battery piece, the starting section 231 and the tail section are different in distance from the first edge 13, and the welding rib can cover the corresponding grid line to ensure stable connection with the grid line.

[0117] Specifically, the starting section 231 of the welding rib on the same battery piece is closer to the first edge 13 of the battery piece, and the tail section 232 of the welding rib is farther from the first edge 13 of the battery piece. The arrangement of the welding rib on the battery piece makes the welding rib present an oblique posture relative to the first edge 13 of the battery piece. The starting section 231 and the tail section 232 of the welding rib cover the corresponding grid line to ensure the stability of current conduction. At the same time, the oblique arrangement of the welding rib relative to the battery piece increases the contact area of the welding rib and the grid line, ensuring the stability and efficiency of current conduction. The starting section 231 and the tail section 232 of the welding rib both cover the grid line, effectively preventing the disconnection of the welding rib and the grid line, and improving the reliability of the connection. In addition, the oblique arrangement of the welding rib relative to the edge of the battery piece flexibly adjusts the contact position of the welding rib and the grid line, and adapts to different types and sizes of battery pieces. The obliquely arranged welding rib can effectively disperse mechanical stress, reduce the damage of the welding point caused by stress concentration, and prolong the service life of the back contact battery module 100.

[0118] Embodiment nine

[0119] Please refer to FIG. 4 and FIG. 5, in some optional embodiments, the first edge 13 of the battery piece is arranged parallel to the doped layer or the grid line.

[0120] Therefore, the first edge 13 and the second edge 14 of the battery piece can extend along the first direction, which is the same as the extension direction of the doped layer or the grid line, so that the battery piece can be in a rectangular shape, facilitating large-scale production and arrangement, and improving space utilization.

[0121] Embodiment ten

[0122] Please refer to FIG. 1 and FIG. 6, the preparation method of the back contact battery module 100 provided by the embodiment of the present disclosure comprises:

[0123] 01, placing a plurality of battery pieces (not labeled in the figure) along a first direction to form a battery string 200 array;

[0124] 02, laying a welding rib (not labeled in the figure) on the back surface 12 of the battery piece along a third direction, the welding rib being in a strip shape and at least partially covering a doped layer of the battery piece or a grid line arranged on the doped layer, wherein the included angle between the first direction and the third direction is an acute angle;

[0125] 03, disconnecting the welding rib at a predetermined position;

[0126] 04, placing an adhesive film and a back plate on the side of the battery piece provided with the welding rib to form a to-be-laminated piece;

[0127] 05, frame the to-be-laminated piece and install it, and weld the junction box to form the back contact battery assembly 100.

[0128] In the back contact battery assembly 100 and the preparation method thereof in the embodiments of the present disclosure, the back contact battery assembly 100 comprises a battery string 200 and a solder strip, the battery string 200 comprises a plurality of battery pieces, the battery piece has opposite front and back surfaces 12, the back surface 12 is provided with a first doped layer 123 and a second doped layer 124, the first doped layer 123 and the second doped layer 124 extend along a first direction and are alternately distributed along a second direction, wherein the first direction and the second direction intersect, the solder strip is arranged on at least two battery pieces and respectively electrically connects the first doped layer 123 of the battery piece and the second doped layer 124 of the adjacent battery piece, the solder strip extends along a third direction and is alternately distributed along the second direction, wherein the included angle between the first direction and the third direction is an acute angle, and the doping polarities of the first doped layer 123 and the second doped layer 124 are opposite. In this way, the solder strip can be arranged to be inclined to the doped layer at an acute angle, so as to increase the contact area of the solder strip and the battery piece, thereby increasing the electrical contact area of the solder strip and the doped layer and improving the conduction efficiency of the doped layer to the solder strip. At the same time, the inclined arrangement of the solder strip can relieve the problem of stress concentration, so as to ensure the stable connection of the solder strip and the battery piece.

[0129] Exemplarily, the plurality of battery pieces are placed on the combination of the front plate and the front adhesive film along the first direction to form a battery string 200 array, and the number of battery pieces is not limited, so as to realize the design of different numbers of battery strings 200. The entire production line extends along the first direction as the reference, and all the battery pieces are laid with the front surface downward and the back surface 12 upward, then step 02 is performed, and the solder strip is laid on the plurality of battery pieces along the third direction. At this time, one solder strip can connect the grid lines of all the battery pieces in the same straight line along the third direction. Then, the solder strip at the predetermined position is cut off by laser cutting or other technologies, to form the series-connected battery string 200. The back adhesive film and the back plate are placed on the side of the battery piece provided with the solder strip to form a to-be-laminated piece; finally, the to-be-laminated piece is framed and installed, and the junction box is welded to form the back contact battery assembly 100.

[0130] Specifically, during the process preparation, one solder strip can be arranged on the same straight grid lines of multiple cell pieces at the same time, and then can be disconnected at a predetermined position to ensure that the solder strip can connect the first grid line 121 and the second grid line 122 of the adjacent cell pieces. For example, the solder strip can connect the first grid line 121 of the first cell piece and the second grid line 122 of the second cell piece, and then be disconnected at an end of the second grid line 122 of the second cell piece away from the first cell piece. Similarly, the solder strip can connect the first grid line 121 of the second cell piece and the second grid line 122 of the third cell piece, and then be disconnected at an end of the second grid line 122 of the third cell piece away from the second cell piece. In this way, a continuous cell string 200 can be formed.

[0131] Embodiment eleven

[0132] Referring to FIG. 1 and FIG. 7, the photovoltaic system 300 provided by the embodiments of the present disclosure includes the back contact cell module 100 of any of the above embodiments.

[0133] In the back contact cell module 100, the preparation method thereof, and the photovoltaic system 300 of the embodiments of the present disclosure, the back contact cell module 100 includes a cell string 200 and a solder strip (not labeled in the figure), the cell string 200 includes multiple cell pieces (not labeled in the figure), the cell piece has opposite front and back surfaces 12, the back surface 12 is provided with a first doped layer 123 and a second doped layer 124, the first doped layer 123 and the second doped layer 124 extend along a first direction and are alternately distributed along a second direction, wherein the first direction and the second direction intersect, the solder strip is arranged on at least two cell pieces and respectively electrically connects the first doped layer 123 of the cell piece and the second doped layer 124 of the adjacent cell piece, the solder strip extends along a third direction and is alternately distributed along the second direction, wherein the included angle between the first direction and the third direction is an acute angle, and the doping polarities of the first doped layer 123 and the second doped layer 124 are opposite. In this way, the solder strip can be arranged to be inclined to the doped layer at an acute angle to increase the contact area of the solder strip and the cell piece, thereby increasing the electrical contact area of the solder strip and the doped layer and improving the conduction efficiency of the doped layer to the solder strip. At the same time, the inclined arrangement of the solder strip can relieve the problem of stress concentration to ensure the stable connection of the solder strip and the cell piece.

[0134] In the present embodiment, the photovoltaic system 300 can be applied in a photovoltaic power station, such as a ground power station, a roof power station, a water surface power station, etc., and can also be applied in a device or apparatus that utilizes solar energy to generate power, such as a user solar power source, a solar street lamp, a solar car, a solar building, etc. Of course, it can be understood that the application scenarios of the photovoltaic system 300 are not limited to this, that is, the photovoltaic system 300 can be applied in all fields that need to utilize solar energy to generate power. Taking a photovoltaic power generation system network as an example, the photovoltaic system 300 can include a photovoltaic array, a combiner box, and an inverter, the photovoltaic array can be an array combination of a plurality of back contact cell assemblies 100, for example, a plurality of back contact cell assemblies 100 can form a plurality of photovoltaic arrays, the photovoltaic arrays are connected to the combiner box, the combiner box can combine the currents generated by the photovoltaic arrays, the combined currents flow through the inverter to be converted into alternating current required by a power grid, and then the alternating current is connected to a power network to realize solar power supply.

[0135] In the description of the present specification, the description referring to the terms "some embodiments", "exemplary embodiments", "examples", "specific examples", 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 one embodiment or example of the present disclosure. In the present specification, 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 one or more embodiments or examples in a suitable manner.

[0136] In addition, the above are only the preferred embodiments of the present disclosure and are not intended to limit the present disclosure. Any modification, equivalent replacement and improvement made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A back contact cell assembly, comprising: a cell string comprising a plurality of cell pieces, the cell pieces having opposite front and back surfaces, the back surface being provided with first and second doped layers, the first and second doped layers extending along a first direction and being alternately distributed along a second direction, wherein the first and second directions intersect; solder strips provided on at least two of the cell pieces and electrically connecting the first doped layer of the cell piece and the second doped layer of an adjacent cell piece, respectively, the solder strips extending along a third direction and being alternately distributed along the second direction, wherein an included angle between the first and third directions is an acute angle; the first and second doped layers having opposite doping polarities.

2. The back contact solar cell assembly of claim 1, wherein, an included angle α between the first and third directions satisfies the following relationship: 0 < tan α ≤ D / L; wherein L is a total length of the most distal ends of a first cell piece and a last cell piece in the cell string along the first direction, and D is a width of any one of the doped layers of the cell pieces along the second direction.

3. The back contact solar cell assembly of claim 1, wherein, the first and second doped layers have equal widths along the second direction.

4. The back contact solar cell assembly of claim 3, wherein, in the second direction, a center distance between two adjacent solder strips is equal; a center distance between two adjacent doped layers is equal; a center distance between two adjacent doped layers is equal to a center distance between two adjacent solder strips.

5. The back contact solar cell assembly of claim 1, wherein, the back surface is provided with first and second grid lines, the first and second grid lines extending along the first direction and being alternately distributed along the second direction, the first grid lines being provided on the first doped layers, and the second grid lines being provided on the second doped layers, the solder strips covering the first grid lines of the cell piece and the second grid lines of an adjacent cell piece.

6. The back contact solar cell assembly of claim 5, wherein, a center distance between two adjacent grid lines is equal; a center distance between two adjacent grid lines is equal to a center distance between two adjacent solder strips.

7. The back contact solar cell assembly of claim 5, wherein, the solder strips are parallel to each other; the first and second grid lines, the first and second doped layers are parallel to each other.

8. The back contact solar cell assembly of claim 5, wherein, the solder strips comprise first and second sides, the first and second sides extending along the third direction, on any cell piece, the first side comprises a start segment and a tail segment, a distance between a grid line and the start segment is greater than a distance between the grid line and the tail segment.

9. The back contact solar cell assembly of claim 8, wherein, the cell pieces are rectangular, the cell pieces comprise first and second cell pieces provided in sequence along the first direction, the cell pieces comprise first and second edges distributed along the second direction, a grid line closest to the first edge of the first cell piece is the first grid line, and a grid line closest to the first edge of the second cell piece is the second grid line.

10. The back contact solar cell assembly of claim 9, wherein, the solder strips are long strips, a width of the solder strips is less than a spacing between the first and second grid lines.

11. The back contact solar cell assembly of claim 9, wherein, the solder strips comprise first and second solder strips, the first and second solder strips extending along the third direction and being alternately distributed along the second direction; The first solder strip covers and connects the first doped layer or the first busbar of the first cell and the second doped layer or the second busbar of the second cell; The second solder strip covers and connects the second doped layer or the second busbar of the first cell and the first doped layer or the first busbar of another second cell.

12. The back contact solar cell assembly of claim 9, wherein, The distance between the starting section and the first edge of the cell is less than the distance between the tail section and the first edge of the cell.

13. The back contact solar cell assembly of claim 9 or 12, wherein, The first edge of the cell is parallel to the doped layer or the busbar.

14. A method for manufacturing a back contact cell module, comprising: placing a plurality of cells in a first direction to form an array of cell strings; laying a solder strip in a third direction on the back of the cells, the solder strip being in a strip shape to at least partially cover one doped layer of the cells or one busbar disposed on the doped layer, wherein the included angle between the first direction and the third direction is an acute angle; cutting the solder strip at a predetermined position; placing a back adhesive film and a back plate on the side of the cells provided with the solder strip to form a to-be-laminated piece; framing and mounting the to-be-laminated piece, and welding a junction box to form a back contact cell module.

15. A photovoltaic system comprising the back contact cell module according to any one of claims 1-13.

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