Back contact cells and photovoltaic modules

Abstract

This application relates to the field of solar cells, providing a back-contact cell and a photovoltaic module. The back-contact cell includes: a first fine grid and a second fine grid arranged at intervals along a first direction on a second surface of a substrate; a first edge main grid and a second edge main grid respectively disposed on opposite sides of the first and second fine grids along a second direction, the first edge main grid being electrically connected to the first fine grid, and the second edge main grid being electrically connected to the second fine grid; a first edge pad and a second edge pad correspondingly disposed on the side of the first and second edge main grids closest to the fine grids; a first connecting electrode connecting the first edge main grid and the first edge pad; a second connecting electrode connecting the second edge main grid and the second edge pad; a first connecting line and a second connecting line intersecting and electrically contacting the first connecting electrode and the second connecting electrode, respectively, which at least improves the performance and yield of the back-contact cell.

Description

Technical Field

[0001] This application relates to the field of solar cells, and particularly to a back-contact battery and photovoltaic module. Background Technology

[0002] Currently, with the gradual depletion of fossil fuels, solar cells are becoming increasingly widely used as a new energy alternative. A solar cell is a device that converts solar energy into electrical energy. Solar cells utilize the photovoltaic principle to generate charge carriers, and then use electrodes to extract these carriers, thus facilitating the efficient use of electrical energy.

[0003] Back-contact (BC) cells are a common solar cell technology. BC cell technology moves the PN junction and grid contacts to the back of the cell, eliminating grid obstruction on the front and increasing the area of ​​the cell that absorbs sunlight, thereby improving conversion efficiency and generating more electricity.

[0004] However, existing technologies suffer from the problem that charge carriers in the edge region of the back contact battery cannot be fully absorbed, affecting the performance and yield of the back contact battery. Utility Model Content

[0005] This application provides a back-contact battery and a photovoltaic module, which at least helps to solve the problem that the charge carriers in the edge region of the back-contact battery cannot be fully absorbed, thus affecting the performance and yield of the back-contact battery.

[0006] According to some embodiments of the present application, in one aspect of the embodiments of the present application, there is provided a back-contact battery, comprising: a substrate, wherein the substrate comprises a first surface and a second surface opposite to each other; a first doped region and a second doped region located on the second surface; a plurality of fine grids arranged at intervals along a first direction, wherein the fine grids extend along a second direction, the plurality of fine grids comprise a first fine grid and a second fine grid with different polarities, the first fine grid is in electrical contact with the first doped region, and the second fine grid is in electrical contact with the second doped region; a first edge main grid and a second edge main grid, which are respectively arranged on opposite sides of the fine grid in the second direction, the first edge main grid is electrically connected to the first fine grid, and the second edge main grid is electrically connected to the second fine grid; a first edge pad arranged on a side of the first edge main grid close to the fine grids; a second edge pad arranged on a side of the second edge main grid close to the fine grids; a first connecting electrode arranged between the first edge main grid and the first edge pad to connect the first edge main grid and the first edge pad; a second connecting electrode arranged between the second edge main grid and the second edge pad to connect the second edge main grid and the second edge pad; a first connecting wire arranged to intersect with the first connecting electrode and in electrical contact therewith, the first connecting wire being in electrical contact with the first doped region; a second connecting wire arranged to intersect with the second connecting electrode and in electrical contact therewith, the second connecting wire being in electrical contact with the second doped region.

[0007] In some embodiments, a plurality of said first connecting wires are arranged at intervals along said second direction, said first connecting electrode extends along said second direction, and said first connecting wires are arranged to cross said first connecting electrode.

[0008] In some embodiments, the intersection position of said first connecting wire and said first connecting electrode is located in other regions of said first connecting wire except the head and tail ends.

[0009] In some embodiments, the intersection position of said first connecting wire and said first connecting electrode is located at the head and tail ends of said first connecting wire.

[0010] In some embodiments, the pitch between adjacent said first connecting wires is 0.1 mm to 5 mm.

[0011] In some embodiments, said first connecting wire is arranged overlapping with said first connecting electrode, and said first connecting electrode covers said first connecting wire.

[0012] In some embodiments, N is the width of said first connecting electrode, M is the width of said first doped region, Z is the length of said first connecting wire, and W is the width of said first connecting wire; wherein N<M, Z<M, and W<M.

[0013] In some embodiments, N is 0.02mm to 0.5mm and W is 0.01mm to 0.1mm.

[0014] According to some embodiments of this application, another aspect of this application provides a photovoltaic module, including: a battery string, formed by connecting a plurality of back-contact batteries as described in the previous embodiment; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film away from the battery string.

[0015] The technical solution provided in this application has at least the following advantages:

[0016] The back contact battery provided in this application includes multiple fine grids spaced apart on the second surface of a substrate, including a first fine grid and a second fine grid with different polarities; a first edge main grid disposed on one side of opposite sides of the fine grids in a second direction, electrically connected to the first fine grids, for collecting charge carriers absorbed by the first fine grids; a first edge pad disposed on the side of the first edge main grid close to the fine grids; a first connecting electrode connecting the first edge main grid and the first edge pad, for transferring the charge carriers collected by the main grid to the first edge pad; and a first connecting line intersecting and electrically contacting the first connecting electrode, and also electrically contacting a first doped region, for absorbing charge carriers in the doped semiconductor layer within the region and transferring them to the first edge pad through the first connecting electrode. This application embodiment can effectively absorb charge carriers in the edge region of the back contact battery, which is beneficial for improving the performance and yield of the back contact battery. Attached Figure Description

[0017] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A top view of the back contact battery provided in an embodiment of this application;

[0019] Figure 2 A cross-sectional structural diagram of the back contact battery provided in an embodiment of this application;

[0020] Figure 3 A schematic diagram of a partial electrode structure of a back contact battery provided in an embodiment of this application;

[0021] Figure 4 A schematic diagram of another partial electrode structure of the back contact battery provided in an embodiment of this application;

[0022] Figure 5 This is a schematic diagram of another partial electrode structure of the back contact battery provided in an embodiment of this application;

[0023] Figure 6 This is a partial three-dimensional structural diagram of a photovoltaic module provided in an embodiment of this application;

[0024] Figure 7 Provided for the embodiments of this application Figure 6 A partial cross-sectional schematic diagram along the cross-sectional direction AA1.

[0025] Explanation of reference numerals in the attached figures:

[0026] Substrate 100, first surface 101, second surface 102, first doped region 112, second doped region 122, fine grid 103, first fine grid 113, second fine grid 123, first edge main grid 114, second edge main grid 124, first edge pad 115, second edge pad 125, first connecting electrode 116, second connecting electrode 126, first connecting line 117, second connecting line 127, first main grid 118, second main grid 128, first pad 119, second pad 129, back contact battery 20, encapsulation film 21 and cover plate 22, middle region I, side regions II, first direction Y, second direction X. Detailed Implementation

[0027] In back-contact batteries, charge carriers collected by the fine grid need to be gathered at the main grid, then transferred to the pads via the connection electrode between the main grid and the pads, and finally output to the external circuitry. However, the distance between the edge main grid and the pads is relatively large. During the transmission process, the high transmission resistance easily leads to carrier recombination and energy loss, thus affecting the overall conversion efficiency and manufacturing yield of the back-contact battery. Furthermore, since the connection electrode between the edge main grid and the pads does not contact the substrate, charge carriers in that area cannot be fully absorbed, affecting the performance and yield of the back-contact battery, resulting in a blackening phenomenon at the edge of the back-contact battery under electroluminescence imaging.

[0028] This application provides a back-contact battery, in which a first connecting line is provided at the edge region of the back-contact battery for electrical contact with the substrate, thereby absorbing charge carriers in the doped semiconductor layer within that region. This embodiment effectively absorbs charge carriers at the edge region of the back-contact battery, which is beneficial for improving the performance and yield of the back-contact battery.

[0029] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined. Similarly, "multiple sets" refers to two or more sets (including two sets), and "multiple pieces" refers to two or more pieces (including two pieces).

[0030] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0031] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0032] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. For example, if the device or element in the illustration is inverted, then the element described as "below," "under," "below," or "bottom" of other elements or features will be oriented "above" or "top" of said other elements or features. Therefore, the term "below" may cover both above and below orientation depending on the context in which the term is used, which will be obvious to those skilled in the art. Materials may be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0033] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0034] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. Furthermore, when describing a component as "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0035] In the description of the embodiments of this application, when a component "includes" another component, it does not exclude other components unless otherwise stated, and other components may be further included. The formation or provision of a second component above or on a first component, or on the surface of a first component, or on one side of a first component, may include embodiments where the first and second components are in direct electrical contact, and may also include embodiments where an additional component may be present between the first and second components, thereby allowing the first and second components to not be in direct electrical contact. For simplicity and clarity, various components may be drawn at different scales. In the drawings, some layers / components may be omitted for simplicity. Unless otherwise specified, the formation or provision of a second component on the surface of a first component refers to direct electrical contact between the first and second components. The term "component" can refer to a layer, film, region, portion, structure, etc.

[0036] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "component" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0037] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0038] Figure 1A top view of the back contact battery provided in an embodiment of this application; Figure 2 A cross-sectional structural diagram of the back contact battery provided in an embodiment of this application; Figure 3 A schematic diagram of a partial electrode structure of a back contact battery provided in an embodiment of this application; Figure 4 A schematic diagram of another partial electrode structure of the back contact battery provided in an embodiment of this application; Figure 5 This is a schematic diagram of another partial electrode structure of the back contact battery provided in an embodiment of this application.

[0039] refer to Figures 1 to 5 A back contact battery includes: a substrate 100, the substrate 100 including a first surface 101 and a second surface 102 opposite to each other.

[0040] The first doped region 112 and the second doped region 122 are located on the second surface 102.

[0041] Multiple fine gates 103 are arranged at intervals along the first direction Y. The fine gates 103 extend along the second direction X. The multiple fine gates 103 include a first fine gate 113 and a second fine gate 123 with different polarities. The first fine gate 113 is in electrical contact with the first doped region 112, and the second fine gate 123 is in electrical contact with the second doped region 122.

[0042] The first edge main gate 114 and the second edge main gate 124 are respectively disposed on opposite sides of the fine gate 103 in the second direction X. The first edge main gate 114 is electrically connected to the first fine gate 113, and the second edge main gate 124 is electrically connected to the second fine gate 123.

[0043] The first edge pad 115 is located on the side of the first edge main gate 114 near the fine gate 103.

[0044] The second edge pad 125 is located on the side of the second edge main gate 124 near the fine gate 103.

[0045] A first connecting electrode 116 is disposed between the first edge main gate 114 and the first edge pad 115 to connect the first edge main gate 114 and the first edge pad 115.

[0046] The second connecting electrode 126 is disposed between the second edge main gate 124 and the second edge pad 125 to connect the second edge main gate 124 and the second edge pad 125.

[0047] The first connecting line 117 is intersecting and electrically contacting the first connecting electrode 116, and the first connecting line 117 is electrically contacting the first doped region 112.

[0048] The second connecting line 127 is intersecting and electrically contacting the second connecting electrode 126, and the second connecting line 127 is electrically contacting the second doped region 122.

[0049] The substrate 100 is used to receive incident light and generate photogenerated carriers. In some embodiments, the substrate 100 may be a semiconductor substrate, such as silicon, germanium, germanium-silicon, or silicon on an insulator.

[0050] In some embodiments, the material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material may be monocrystalline, polycrystalline, amorphous, or microcrystalline (a state simultaneously possessing both monocrystalline and amorphous states is called microcrystalline). For example, silicon may be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. If the substrate material is silicon, then the material of the substrate 100 may include at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0051] In some embodiments, the substrate 100 may also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium arsenide, perovskite, cadmium telluride, copper indium selenide, etc. Materials may also be silicon carbide, organic materials, or multi-component compounds. Multi-component compounds may include, but are not limited to, perovskite, gallium arsenide, cadmium telluride, copper indium selenide, etc.

[0052] The substrate 100 can also be a sapphire substrate, a silicon substrate on an insulator, or a germanium substrate on an insulator.

[0053] The substrate 100 can be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type dopant element, which can be any one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate is doped with a P-type dopant element, which can be any one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0054] In some embodiments, the substrate 100 includes a first surface 101 and a second surface 102. If the back contact battery is a single-sided battery, then the first surface 101 of the substrate 100 serves as the light-receiving surface for receiving incident light, and the second surface 102 of the substrate 100 serves as the back-lighting surface.

[0055] In some embodiments, the second surface 102 of the back contact battery includes a first doped region 112 and a second doped region 122 arranged sequentially at intervals, wherein the first doped element in the first doped region 112 and the second doped element in the second doped region 122 have different conductivity types.

[0056] In some embodiments, the first doped region 112 is doped with dopant ions of the same conductivity type as the substrate 100, and the second doped region 122 is doped with dopant ions of a different conductivity type than the substrate. For example, if the substrate is an N-type substrate, the first doped region 112 is an N-type doped layer, and the second doped region 122 is a P-type doped layer, then the second doped region 122 and the substrate 100 form a PN junction, effectively shunting charge carriers.

[0057] Fine gates 103 are distributed on the second surface 102 for efficient carrier collection. The first fine gate 113 and the second fine gate 123 are arranged alternately on the second surface 102, forming a two-dimensional mesh structure. This alternating arrangement of the first fine gate 113 and the second fine gate 123 ensures a uniform current distribution in the first doped region 112 and the second doped region 122, reducing energy loss caused by excessively high local current density. Furthermore, this staggered arrangement maximizes the use of space on the second surface 102, improving current collection efficiency.

[0058] The first edge main gate 114 and the second edge main gate 124 are respectively responsible for collecting the current collected by the first fine gate 113 and the second fine gate 123.

[0059] The first edge pad 115 and the second edge pad 125 are used to collect the current collected by the first edge main gate 114 and the second edge main gate 124, respectively, and to lead it to the external circuit.

[0060] The first connecting electrode 116 is used to transfer the current collected by the first edge main gate 114 to the first edge pad 115, and the second connecting electrode 126 is used to transfer the current collected by the second edge main gate 124 to the second edge pad 125. Neither the first connecting electrode 116 nor the second connecting electrode 126 makes contact with the substrate 100, effectively avoiding damage to the passivation layer caused by localized penetration or damage during the metal material formation process. This helps protect the integrity of the passivation layer on the substrate surface and prevents carrier recombination loss due to passivation failure, thereby improving the stability and reliability of the device while ensuring electrical performance.

[0061] The first connecting line 117 and the second connecting line 127 are in contact with the substrate for collecting charge carriers in their respective regions. The first connecting line 117 is in electrical contact with the first connecting electrode 116 for transferring the collected charge carriers to the first edge pad 115 via the first connecting electrode 116; the second connecting line 127 is in electrical contact with the second connecting electrode 126 for transferring the collected charge carriers to the second edge pad 125 via the second connecting electrode 126.

[0062] In some embodiments, the first connecting line 117 is intersecting with the first connecting electrode 116, and the second connecting line 127 is intersecting with the second connecting electrode 126. This can effectively avoid the problem of the first connecting line 117 or the second connecting line 127 being printed on the first connecting electrode 116 or the second connecting electrode 126, which would prevent the effective absorption of charge carriers. This is beneficial for improving the charge carrier collection capability and the yield of the back contact battery.

[0063] The back-contact battery provided in this application improves current collection capability by placing the first edge main gate on one side of the opposite sides of the fine gate in the second direction X and electrically connecting it to the first fine gate. This allows the main gate to efficiently collect the charge carriers absorbed by the first fine gate. By placing the first edge pad on the side of the first edge main gate closer to the fine gate, the connection path between the main gate and the pad is shortened, reducing transmission resistance and improving current output efficiency. By setting the first connecting electrode to connect the first edge main gate and the first edge pad, charge carriers can be transferred from the main gate to the pad through a low-resistance path, improving current transmission efficiency. By setting the first connecting line to cross the first connecting electrode and form an electrical contact, and simultaneously making an electrical contact with the first doped region 112, charge carriers in areas originally far from the fine gate can also be effectively absorbed and transferred to the first edge pad through the connecting electrode, thereby significantly improving the overall performance and yield of the device.

[0064] The embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0065] In some embodiments, a plurality of first connecting lines 117 are arranged at intervals along the second direction X, and a first connecting electrode 116 extends along the second direction X, with the first connecting lines 117 and the first connecting electrode 116 intersecting each other; a plurality of second connecting lines 127 are arranged at intervals along the second direction X, and a second connecting electrode 126 extends along the second direction X, with the second connecting lines 127 and the second connecting electrode 126 intersecting each other.

[0066] In some embodiments, multiple first connection lines 117 are arranged at intervals to achieve uniform coverage of the region between the first edge main gate 114 and the first edge pad 115, which is beneficial for fully collecting charge carriers located in the region between the first edge main gate 114 and the first edge pad 115. The multiple first connection lines 117 are arranged to intersect with the first connection electrode 116, so that all the charge carriers collected by the first connection lines 117 can be transferred to the first edge pad 115 through the first connection electrode 116, effectively expanding the collection path of charge carriers and improving the collection efficiency of charge carriers.

[0067] refer to Figure 2In some embodiments, the intersection of the first connecting line 117 and the first connecting electrode 116 is located in other areas of the first connecting line 117 except for the beginning and end ends; the intersection of the second connecting line 127 and the second connecting electrode 126 is also located in other areas of the second connecting line 127 except for the beginning and end ends.

[0068] The intersection point refers to the specific location where the first connecting line 117 and the first connecting electrode 116 form an electrical connection through contact. Other areas besides the beginning and end points refer to the area within the intersection point (such as the middle or near the middle) of the first connecting line 117, avoiding its starting and ending points.

[0069] In some embodiments, by setting the intersection position in the middle or other non-end regions of the first and second connecting lines, it has the advantages of simple process and low cost, and is suitable for battery designs with relatively simple manufacturing process requirements.

[0070] refer to Figure 3 In some embodiments, the intersection of the first connecting line 117 and the first connecting electrode 116 is located at the beginning and end of the first connecting line 117; the intersection of the second connecting line 127 and the second connecting electrode 126 is also located at the beginning and end of the second connecting line 127.

[0071] In some embodiments, the first connecting electrode 116 and the first connecting line 117 form two electrical connection points at the beginning and end of the first connecting line 117, effectively shortening the current transmission path, optimizing the uniformity of current distribution, and avoiding power loss caused by current concentration, thereby improving the carrier collection efficiency. This design is particularly suitable for high-efficiency back-contact batteries, helping to improve their overall performance and reliability.

[0072] In some embodiments, the first connecting electrode 116 and the first connecting line 117 form two electrical connection points at the beginning and end of the first connecting line 117. An additional connection point can also be provided in the middle of the first connecting line 117, achieving a composite structure combining beginning-end and middle connections. This design not only effectively shortens the current transmission path and optimizes the uniformity of current distribution, but also avoids power loss caused by current concentration, thereby significantly improving carrier collection efficiency.

[0073] Furthermore, the first connecting electrode 116 can be in the form of multiple parallel distributions to match the current density requirements of different regions, which is especially suitable for high-efficiency back contact battery structures.

[0074] In some embodiments, different connection methods can be used in the regions where the first doped region 112 and the second doped region 122 of the back contact battery are located (e.g., the region where the first doped region 112 is located is connected at both ends, and the region where the second doped region 122 is located is connected in the middle) to achieve a balance between carrier collection efficiency and manufacturing cost.

[0075] In some embodiments, the spacing between adjacent first connecting lines 117 is 0.1mm to 5mm. For example, it can be 0.1mm, 1mm, 2mm, 3mm, 4mm or 5mm; the spacing between adjacent first connecting lines 117 is also 0.1mm to 5mm. For example, it can be 0.1mm, 1mm, 2mm, 3mm, 4mm or 5mm.

[0076] In some embodiments, if the spacing between adjacent first connection lines 117 is less than 0.1 mm, it may result in excessive metal coverage, significantly increasing the obstruction of incident light from the back side and reducing the back-side photoelectric conversion efficiency. Since back-side power generation relies on reflected or scattered light, this obstruction effect leads to a significant decrease in back-side efficiency, resulting in a bifaciality problem, i.e., a decrease in the ratio of back-side efficiency to front-side efficiency. Furthermore, it significantly increases manufacturing difficulty and cost. Conversely, if the spacing between adjacent first connection lines 117 is greater than 5 mm, the lateral transport path of charge carriers becomes too long, leading to increased recombination losses and localized blackening in electroluminescence imaging, affecting the overall performance and yield of the back-contact battery. Therefore, limiting the spacing between adjacent first connection lines 117 to the range of 0.1 mm to 5 mm achieves the optimal balance between efficient charge carrier collection and manufacturing feasibility, effectively improving the lateral transport efficiency of charge carriers and reducing recombination losses caused by excessively long paths.

[0077] In some embodiments, the spacing between adjacent first connecting lines 117 is preferably 0.5mm to 2mm. For example, it can be 0.5mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 1.8mm, or 2mm; the spacing between adjacent second connecting lines 127 is also preferably 0.5mm to 2mm. For example, it can be 0.5mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 1.8mm, or 2mm.

[0078] This spacing setting, based on optimized bifaciality, achieves full coverage of the edge-doped region, avoiding carrier transport dead zones, thus balancing carrier collection efficiency and metal material usage.

[0079] refer to Figure 4, in some embodiments, the first connecting line 117 is arranged overlapping the first connecting electrode 116, and the first connecting electrode 116 covers the first connecting line 117. The second connecting line 127 is arranged overlapping the second connecting electrode 126, and the second connecting electrode 126 covers the second connecting line 127.

[0080] In this embodiment, during the preparation of the back-contact battery, the first connecting line 117 is formed first, so that it can achieve good contact with the substrate and fully absorb carriers in its region; then the first connecting electrode 116 is formed on the first connecting line 117, and the first connecting electrode 116 covers or partially covers the first connecting line 117, thereby increasing the contact area therebetween and improving the current conduction capability and structural stability.

[0081] In some other embodiments, the first connecting electrode 116 may also be formed first, and then the first connecting line 117 is formed thereon, so as to achieve electrical connection between the first connecting line 117 and the first connecting electrode 116.

[0082] In some embodiments, N is the width of the first connecting electrode 116, M is the width of the first doped region 112, Z is the length of the first connecting line 117, W is the width of the first connecting line 117; wherein N<M, Z<M, and W<M.

[0083] In some embodiments, N is the width of the second connecting electrode 126, M is the width of the second doped region 122, Z is the length of the second connecting line 127, and W is the width of the second connecting line 127.

[0084] Wherein, the width of the first connecting electrode 116 refers to the width of the first connecting electrode 116 in the direction perpendicular to the extending direction of the first connecting electrode 116, the width of the first connecting line 117 refers to the width of the first connecting line 117 in the direction perpendicular to the extending direction of the first connecting line 117, and the width of the second doped region 122 is the width of the second doped region 122 in the first direction Y.

[0085] Both the width of the first connecting electrode 116 and the width of the first connecting line 117 are smaller than the width of the first doped region 112, so as to ensure that the first connecting electrode 116 and the first connecting line 117 are both completely located in the region where the first doped region 112 is located, avoiding the risk of short circuit or leakage current caused by the excessively long length of the first connecting line 117 intruding into the adjacent second doped region 122; in addition, reasonably controlling the width of the first connecting electrode 116 and the width of the first connecting line 117 is beneficial to reducing the consumption of silver paste, lowering material costs, and improving the overall yield and stability of the back-contact battery.

[0086] In some embodiments, N is 0.02mm to 0.5mm, for example, it can be 0.02mm, 0.1mm, 0.12mm, 0.2mm, 0.22mm, 0.3mm, 0.32mm, 0.4mm, 0.42mm or 0.5mm; W is 0.01mm to 0.1mm, for example, it can be 0.01mm, 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm or 0.1mm.

[0087] In some embodiments, if the width of the first connecting electrode 116 is less than 0.02 mm, the resistance will increase significantly, affecting the output performance and long-term stability of the device. Conversely, if the width of the first connecting electrode 116 is greater than 0.5 mm, it will lead to increased cost and performance degradation due to increased bifaciality, increased silver paste usage, and increased risk of edge short circuits. In this embodiment, by controlling the width of the first connecting electrode 116 within the range of 0.02 mm to 0.5 mm, the series resistance can be effectively reduced, the current transmission capability improved, and the production yield increased.

[0088] In some embodiments, if the width of the first connecting line 117 is less than 0.01 mm, it will result in excessively high resistance of the carrier transport path, making manufacturing difficult and prone to breakage. Conversely, if the width of the first connecting line 117 is greater than 0.1 mm, it will lead to layout limitations and decreased matching with the first connecting electrode 116, further affecting the overall performance of the back contact battery. In this embodiment, the width of the first connecting line 117 is controlled within the range of 0.01 mm to 0.1 mm, which can avoid the bifaciality problem and the risk of breakage due to excessively narrow line width.

[0089] In some embodiments, the first connecting line 117 and the second connecting line are made of the same material as the fine grid.

[0090] The first connecting line 117, the second connecting line, and the fine grid are all made of conductive materials, such as silver paste, copper paste, or aluminum paste. Therefore, the first connecting line 117, the second connecting line, and the fine grid can be formed in the same process during the fabrication of the back contact battery.

[0091] For example, patterning the first connecting line 117, the second connecting line, and the fine grid is completed in the same screen printing or sputtering deposition process. By unifying the materials and process flow, multiple metal deposition and etching operations are avoided, the manufacturing process is simplified, and production costs are reduced. In addition, forming the first connecting line 117, the second connecting line, and the fine grid in the same process also helps to improve the alignment accuracy between different metal lines and reduce the risk of poor contact or open circuit caused by process deviations.

[0092] In some embodiments, reference Figure 1 The second surface 102 can be divided into a central region I and two side regions II along the X-axis of its plane. The first edge main gate 114, the second edge main gate 124, the first edge pad 115, the second edge pad 125, the first connecting electrode 116, the second connecting electrode 126, the first connecting line 117, and the second connecting line 127 are all located in the two side regions. The central region I of the second surface 102 also includes:

[0093] The first main gate 118 and the second main gate 128 are arranged alternately along the second direction X. Both the first main gate 118 and the second main gate 128 extend along the first direction Y. The first main gate 118 is electrically connected to the first fine gate 113, and the second main gate 128 is electrically connected to the second fine gate 123.

[0094] First pad 119 and second pad 129, the first pad 119 is disposed on the first main gate 118 and the second pad 129 is disposed on the second main gate 128.

[0095] The first main gate 118 and the second main gate 128 are respectively responsible for collecting the current collected by the first fine gate 113 and the second fine gate 123.

[0096] The first pad 119 and the second pad 129 are used to collect the current collected by the first main gate 118 and the second main gate 128, respectively, and to lead it to the external circuit.

[0097] The back contact battery provided in this application embodiment, by setting a first main gate and a second main gate in the middle region, and setting a first pad and a second pad on the first main gate and the second main gate respectively, allows the current collected by the main gate in the middle region to be directly output to the external circuit through the pad, which helps to shorten the transmission path between the main gate and the pad, reduce the series resistance, and improve the output power; and by setting a first edge main gate, a second edge main gate, a first edge pad, a second edge pad, a first connecting electrode, a second connecting electrode, a first connecting line, and a second connecting line in the two side regions, the carrier collection efficiency and current transmission efficiency are effectively improved, solving the problem of difficult carrier collection and long current transmission path in the edge region of traditional back contact batteries, which is conducive to improving the performance and yield of back contact batteries.

[0098] Accordingly, another aspect of this application also provides a photovoltaic module, including a plurality of back-contact cells as described in the above embodiments. The following will describe in detail another embodiment of the photovoltaic module provided by this application with reference to the accompanying drawings. For parts that are the same as or corresponding to the previous embodiment, please refer to the corresponding descriptions of the foregoing embodiments; detailed descriptions will not be repeated below.

[0099] Figure 6This is a partial three-dimensional structural diagram of a photovoltaic module provided in an embodiment of this application; Figure 7 for Figure 6 A partial cross-sectional schematic diagram along the cross-sectional direction AA1.

[0100] refer to Figure 6 and Figure 7 The photovoltaic module provided in this application includes: a battery string, an encapsulating film 21, and a cover plate 22.

[0101] The battery string is composed of multiple back contact batteries 20 as described in the above embodiment.

[0102] The encapsulating film 21 is used to cover the surface of the battery string.

[0103] Cover plate 22 is used to cover the surface of the encapsulating film 21 away from the battery string.

[0104] In some embodiments, the encapsulating film 21 includes a first encapsulating layer and a second encapsulating layer. The first encapsulating layer covers one of the front or back sides of the solar cell, and the second encapsulating layer covers the other of the front or back sides of the solar cell. Specifically, at least one of the first or second encapsulating layer can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene elastomer (POE) film, or polyethylene terephthalate (PET) film. Alternatively, at least one of the first or second encapsulating layer can also be an EP film, an EPE film, or a PVP film. Here, EP film refers to a co-extruded film composed of stacked EVA film and POE film; EPE film refers to a co-extruded film formed by sequentially stacking EVA film + POE film + EVA film; and PVP film refers to a co-extruded film formed by stacking POE film + EVA film + POE film. Co-extruded films can be prepared by sequentially extruding one or more raw materials onto another pre-made film during the film processing, or by bonding different types of pre-made films together.

[0105] In some cases, the first encapsulation layer and the second encapsulation layer still have a boundary line before lamination. After lamination, the photovoltaic module will no longer have the concept of a first encapsulation layer and a second encapsulation layer. That is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 21.

[0106] In some embodiments, the cover plate 22 can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function. Specifically, the surface of the cover plate 22 facing the encapsulating film 21 can be an uneven surface or a textured surface containing multiple raised structures, thereby increasing the utilization rate of incident light. The cover plate 22 includes a first cover plate and a second cover plate, the first cover plate being opposite to the first encapsulation layer, and the second cover plate being opposite to the second encapsulation layer.

[0107] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A back-contact battery, characterized in that, comprising: a substrate, wherein the substrate comprises opposite first and second surfaces; a first doped region and a second doped region located on the second surface; a plurality of fine grids arranged at intervals along a first direction, said fine grids extending along a second direction, said plurality of fine grids comprise first fine grids and second fine grids with different polarities, said first fine grids are in electrical contact with said first doped region, and said second fine grids are in electrical contact with said second doped region; a first edge main grid and a second edge main grid, which are respectively arranged on opposite sides of said fine grids in said second direction, said first edge main grid is electrically connected to said first fine grids, and said second edge main grid is electrically connected to said second fine grids; a first edge pad arranged on a side of said first edge main grid adjacent to said fine grids; a second edge pad arranged on a side of said second edge main grid adjacent to said fine grids; a first connecting electrode arranged between said first edge main grid and said first edge pad to connect said first edge main grid and said first edge pad; a second connecting electrode arranged between said second edge main grid and said second edge pad to connect said second edge main grid and said second edge pad; a first connecting line arranged intersecting with and electrically contacting said first connecting electrode, said first connecting line being in electrical contact with said first doped region; a second connecting line arranged intersecting with and electrically contacting said second connecting electrode, said second connecting line being in electrical contact with said second doped region.

2. The back contact battery according to claim 1, characterized in that, a plurality of said first connecting lines are arranged at intervals along said second direction, said first connecting electrode extends along said second direction, and said first connecting lines are arranged crossing said first connecting electrode.

3. The back contact battery according to claim 2, characterized in that, the intersection position of said first connecting line and said first connecting electrode is located in other regions of said first connecting line except the head and tail ends thereof.

4. The back contact battery according to claim 2, characterized in that, the intersection position of said first connecting line and said first connecting electrode is located at the head and tail ends of said first connecting line.

5. The back contact battery according to claim 2, characterized in that, the spacing between adjacent said first connecting lines is 0.1mm to 5mm.

6. The back contact battery according to claim 1, characterized in that, said first connecting line is overlapped with said first connecting electrode, and said first connecting electrode covers said first connecting line.

7. The back contact battery according to claim 1, characterized in that, N is the width of said first connecting electrode, M is the width of said first doped region, Z is the length of said first connecting line, and W is the width of said first connecting line; wherein N<M, Z<M, and W<M.

8. The back contact battery according to claim 7, characterized in that, said N is 0.02mm to 0.5mm, and said W is 0.01mm to 0.1mm.

9. A photovoltaic module, characterized in that, comprising: a battery string formed by connecting a plurality of back-contact batteries according to any one of claims 1 to 8; an encapsulation adhesive film for covering the surface of said battery string; a cover plate for covering the surface of said encapsulation adhesive film away from said battery string.

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