Back contact solar cell and stacked cell, photovoltaic module

Abstract

The embodiment of the present application relates to the field of solar cells, and provides a back contact solar cell, a laminated cell and a photovoltaic module, the back contact solar cell comprising: a substrate, the substrate having a first edge; first grid lines and second grid lines arranged at intervals in a first direction; an edge connecting line and a first pad, the edge connecting line being close to the first edge; a first distance between the first pad and the first edge being greater than a second distance between the edge connecting line and the first edge; wherein a part of the first grid lines adjacent to the first pad comprises first grid line segments and second grid line segments arranged at intervals, the first grid line segments being electrically connected to the edge connecting line, and the second grid line segments being electrically connected to the first pad; a part of the second grid lines adjacent to the first pad comprises third grid line segments; and a first connecting grid line, the first connecting grid line being electrically connected to m third grid line segments, m being greater than or equal to 3.

Description

Technical Field

[0001] This application relates to the field of solar cells, and particularly to a back-contact solar cell, a tandem cell, and a 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 sunlight into electrical energy. Solar cells utilize the photovoltaic principle to generate charge carriers, which are then extracted using electrodes, thus facilitating the efficient utilization of electrical energy.

[0003] Current solar cells mainly include BC cells (back contact cells), TOPCON (Tunnel Oxide Passivated Contact) cells, PERC cells (Passivated emitter and real cell) cells, and heterojunction cells. Different film layer configurations and functional limitations are used to reduce optical losses and decrease photogenerated carrier recombination on and within the silicon substrate, thereby improving the photoelectric conversion efficiency of solar cells.

[0004] However, the photoelectric conversion efficiency of current back-contact solar cells is still unsatisfactory. Summary of the Invention

[0005] This application provides a back-contact solar cell, a tandem cell, and a photovoltaic module, which at least helps to improve the photoelectric conversion efficiency of the back-contact solar cell.

[0006] According to some embodiments of this application, one aspect of this application provides a back-contact solar cell comprising: a substrate having a first edge; first grid lines and second grid lines arranged at intervals along a first direction; an edge connecting line and a first pad, the edge connecting line being close to the first edge; a first distance between the first pad and the first edge being greater than a second distance between the edge connecting line and the first edge; wherein, the portion of the first grid line adjacent to the first pad includes a first grid line segment and a second grid line segment arranged at intervals, the first grid line segment being electrically connected to the edge connecting line, and the second grid line segment being electrically connected to the first pad; the portion of the second grid line adjacent to the first pad includes a third grid line segment; a first connecting grid line electrically connecting m of the third grid line segments, where m ≥ 3.

[0007] In some embodiments, the portion of the second gate line adjacent to the first pad includes the third gate line segment and the fourth gate line segment spaced apart, wherein the number of the fourth gate line segment is less than or equal to the number of the third gate line segment.

[0008] In some embodiments, along the first direction, there are m1 third gate line segments between adjacent first gate lines, where m1 ≥ 2.

[0009] In some embodiments, the first width of the third gate segment along the first direction is less than or equal to the second width of the fourth gate segment along the first direction.

[0010] In some embodiments, the system further includes: a pad connection line, wherein the two ends of the pad connection line are respectively connected to the edge connection line and the first pad; and the first spacing between the third gate segment and the pad connection line is greater than or equal to the second spacing between the third gate segment and the first gate segment.

[0011] In some embodiments, the third gate segment includes m2 first-type gate segments and m3 second-type gate segments, the first-type gate segments and the second-type gate segments being located on both sides of the pad connection line along the first direction, and m2 ≠ m3.

[0012] In some embodiments, the substrate further has a second edge adjacent to the first edge; and further includes: a second pad near the second edge, wherein a portion of the second gate line adjacent to the second pad includes a fifth gate line segment; and a second connecting gate line electrically connecting n of the fifth gate line segments, where n≥3 and m≤n.

[0013] In some embodiments, the substrate further has a second edge adjacent to the first edge, the first pad is close to the second edge, and the third gate segment is close to the second edge.

[0014] In some embodiments, the second gate line further includes an edge gate line located between the third gate line segment and the second edge, and the first connecting gate line electrically connects c of the edge gate lines, where c ≥ 1.

[0015] According to some embodiments of this application, another aspect of this application provides a tandem battery, including: a bottom battery, which is a back-contact solar cell as described in the above embodiments; and a perovskite battery located on one side of the bottom battery.

[0016] 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 solar cells as described in any one of the above embodiments or stacked cells as described in the above embodiments; 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.

[0017] The technical solution provided in this application has at least the following advantages: The back-contact solar cell provided in this application embodiment, by setting an edge connecting line and a first pad, wherein the first distance between the first pad and the first edge is greater than the second distance between the edge connecting line and the first edge, allows the edge connecting line to collect the current between the first grid line and the second grid line. The first pad, which is welded to the solder ribbon, is far from the first edge, thus preventing cracking during cell welding and improving cell yield. The portion of the first grid line adjacent to the first pad includes spaced-apart first grid line segments and second grid line segments. The first grid line segments are electrically connected to the edge connecting line, and the second grid line segments are electrically connected to the first pad. The portion of the second grid line adjacent to the first pad includes third grid line segments. A first connecting grid line electrically connects m third grid line segments, where m ≥ 3. By setting the first connecting grid line and electrically connecting it to multiple third grid line segments, the area of ​​the first pad can be larger within a limited area, facilitating solder ribbon alignment. The larger areas of the first and second grid lines allow for the collection of more current, resulting in higher photoelectric conversion efficiency. Attached Figure Description

[0018] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the drawings 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 art, 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.

[0019] Figure 1 This is a schematic diagram of a back-contact solar cell provided in an embodiment of this application; Figure 2 A cross-sectional view of a back-contact solar cell provided in an embodiment of this application; Figure 3 for Figure 1 A partial view of point A in the middle; Figure 4 for Figure 1Another partial view of point A in the middle; Figure 5 for Figure 1 A partial view of point B in the middle; Figure 6 for Figure 1 A partial view of point B in the middle; Figure 7 A schematic diagram of a stacked battery provided in another embodiment of this application; Figure 8 This is a schematic diagram of a photovoltaic module provided in another embodiment of this application. Detailed Implementation

[0020] As can be seen from the background technology, the photoelectric conversion efficiency of current back-contact solar cells is not good.

[0021] This application provides a back-contact solar cell. By setting a first connecting grid line and electrically connecting the first connecting grid line to multiple third grid line segments, the area of ​​the first pad can be larger in a limited area, which facilitates the alignment of the solder ribbon. The areas of the first grid line and the second grid line are also larger, thereby collecting more current and obtaining a larger photoelectric conversion efficiency.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0026] 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" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to 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.

[0027] 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.

[0028] 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. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "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.

[0029] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may be present therein. Moreover, when a component such as a layer, film, region, or plate is "directly located" on another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it indicates that no other components are located therein.

[0030] 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 "part" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0031] 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.

[0032] According to some embodiments of this application, one aspect of this application provides a back-contact solar cell for improving photoelectric conversion efficiency.

[0033] Figure 1 This is a schematic diagram of a back-contact solar cell provided in an embodiment of this application; Figure 2 A cross-sectional view of a back-contact solar cell provided in an embodiment of this application; Figure 3 for Figure 1 A partial view of point A in the middle; Figure 4 for Figure 1 Another partial view of point A in the middle; Figure 5 for Figure 1 A partial view of point B in the middle; Figure 6 for Figure 1 A partial view of point B in the middle. Among them, Figure 1 The diagram illustrates the structure of the first gate line, the second gate line, and the first pad on one side of the first edge. The gate line structure on the other side of the first edge can be the same or different, and those skilled in the art can make equivalent substitutions.

[0034] It should be noted that, Figure 3 , Figure 4 , Figure 5 as well as Figure 6 for Figure 1 A partial view of the back contact solar cell, but with... Figure 1 The structures do not correspond completely; that is, the embodiments in this application are for illustrating the positional relationship and correspondence between the gate structure and the pads. Figure 1 The back-contact solar cell was modified to form a structure like... Figures 3-6 The partial view shown. Secondly... Figure 1 This is a schematic diagram of the structure of a complete solar cell. The dotted line in the middle can be a dividing line. The back-contact solar cell provided in this application can also be a segmented cell, i.e., for... Figure 1The cells shown are segmented cells formed by slicing a whole cell, such as two-slice cells, three-slice cells, four-slice cells, five-slice cells, six-slice cells, seven-slice cells, or eight-slice cells. Figure 1 The number of gate lines and pads shown are for illustrative purposes only. The actual number of gate lines and pads may be more or less, and those skilled in the art can set them according to their needs. Figure 3 , Figure 4 and Figure 5 , Figure 6 The two cells can be matched together according to the requirements to form a battery cell, but this application does not limit the embodiments thereto.

[0035] refer to Figure 1 as well as Figure 3 According to some embodiments of this application, one aspect of this application provides a back-contact solar cell comprising: a substrate 100 having a first edge 101; first grid lines 11 and second grid lines 12 arranged at intervals along a first direction Y; an edge connecting line 13 and a first pad 14, the edge connecting line 13 being close to the first edge 101; a first distance between the first pad 14 and the first edge 101 being greater than a second distance between the edge connecting line 13 and the first edge 101; wherein, the portion of the first grid line 11 adjacent to the first pad 14 includes a first grid line segment 111 and a second grid line segment 112 arranged at intervals, the first grid line segment 111 being electrically connected to the edge connecting line 13, and the second grid line segment 112 being electrically connected to the first pad 14; the portion of the second grid line 12 adjacent to the first pad 14 includes a third grid line segment 121; a first connecting grid line 123 electrically connecting m third grid line segments 121, where m ≥ 3.

[0036] The back-contact solar cell provided in this application embodiment, by setting an edge connection line 13 and a first pad 14, wherein the first distance between the first pad 14 and the first edge 101 is greater than the second distance between the edge connection line 13 and the first edge 101, allows the edge connection line 13 to collect the current between the first grid line 11 and the second grid line 12, and the first pad 14, which is soldered to the solder ribbon, is far from the first edge 101, thereby preventing the problem of cracking that occurs during cell soldering, and thus improving the yield of the cell. The portion of the first gate line 11 adjacent to the first pad 14 includes a first gate line segment 111 and a second gate line segment 112 spaced apart. The first gate line segment 111 is electrically connected to the edge connecting line 13, and the second gate line segment 112 is electrically connected to the first pad 14. The portion of the second gate line 12 adjacent to the first pad 14 includes a third gate line segment 121. A first connecting gate line 123 is electrically connected to m third gate line segments 121, where m ≥ 3. By setting the first connecting gate line 123 and electrically connecting it to multiple third gate line segments 121, the area of ​​the first pad 14 can be larger within a limited area, thus facilitating solder ribbon alignment. The areas of the first gate line 11 and the second gate line 12 are also larger, thus collecting more current and achieving a higher photoelectric conversion efficiency.

[0037] The back-contact solar cell provided in this application will be described in detail below with reference to the accompanying drawings.

[0038] In some embodiments, back-contact solar cells refer to structures where both the positive and negative metal electrodes are fabricated on the back of the cell, thereby completely eliminating light loss due to shading by the front grid lines and improving efficiency and aesthetics. Back-contact solar cells can be IBC (Interdigitated Back Contact solar cell), EWT (Emitter Wrap-Through solar cell), or MWT (Metal Wrap-Through solar cell). They can also be TBC (Interdigitated Back Contact Tunnel Oxide Passivated Contact solar cell), which combines BC cells and TOPCon cells, and HBC (Silicon Heterojunction Interdigitated Back Contact solar cell), which combines BC cells and heterojunction cells.

[0039] 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.

[0040] 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 dihydrogen phosphate, perovskite, cadmium telluride, and copper indium selenide. The substrate 100 may also be a sapphire substrate, a silicon-on-insulator substrate, or a germanium-on-insulator substrate.

[0041] In some embodiments, 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).

[0042] In some embodiments, reference Figure 2 The front side of the substrate 100 has a textured structure, which can include a regularly shaped pyramidal textured structure and an irregularly shaped black silicon. The beveled surface of the textured structure can increase the internal reflection of incident light, thereby improving the absorption and utilization rate of incident light by the substrate, and thus improving the cell efficiency of the solar cell.

[0043] In some embodiments, the front side of the substrate 100 has a front surface field (FSF) layer, the conductivity type of the doped ions of which is the same as that of the doped ions of the substrate. The field passivation effect is used to reduce the surface minority carrier concentration, thereby reducing the surface recombination rate. At the same time, it can also reduce the series resistance and improve the electron transport capability.

[0044] In some embodiments, the back surface of the substrate 100 is a polished surface, which refers to a smooth surface formed by removing the textured surface structure through a polishing solution or laser etching. The increased surface smoothness after polishing increases the reflection of long-wavelength light, promotes secondary absorption of the projected light, thereby increasing the short-circuit current (Isc). At the same time, the reduced specific surface area of ​​the back surface reduces back recombination and improves the surface passivation effect.

[0045] In some embodiments, the back surface has a first doped region 108 and a second doped region 109 arranged at intervals. The first doped region 108 is doped with dopant ions of the same conductivity type as the substrate 100, and the second doped region 109 is doped with dopant ions of a different conductivity type than the substrate 100. For example, if the substrate is an N-type substrate, the first doped region 108 is an N-type doped region, and the second doped region 109 is a P-type doped region, then the second doped region 109 and the substrate 100 form a PN junction, effectively shunting charge carriers.

[0046] In some embodiments, the doping concentration of doped ions in the first doped region 108 is greater than the doping concentration of doped ions in the substrate 100, and a high-low junction is formed between the first doped region 108 and the substrate 100 to enhance the carrier separation capability.

[0047] In some embodiments, a gap or isolation structure is provided between the first doped region 108 and the second doped region 109 to achieve automatic isolation between regions of different conductivity types. This can eliminate leakage caused by the formation of tunnel junctions between the heavily doped P-region and N-region on the back of the BC battery, which would affect battery efficiency.

[0048] In some embodiments, the passivation layer 133 is located on the surfaces of the first doped region 108 and the second doped region 109.

[0049] The passivation layer 133 may include a single-layer film structure or a stacked film structure, and the material of the passivation layer 133 may be any one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0050] In some embodiments, the first gate line 11 is located on the passivation layer 133 and is electrically connected to the first doped region 108; the second gate line 12 is located on the passivation layer 133 and is electrically connected to the second doped region 109.

[0051] The first grid line 11 and the second grid line 12 are the fine grids (sub-grids) of the solar cell, used to collect and summarize the current of the solar cell.

[0052] In some embodiments, the sub-gate extends along the second direction X. The first direction Y and the second direction X can be perpendicular to each other, or they can have an angle of less than 90 degrees, such as 60 degrees, 45 degrees, 30 degrees, etc., as long as the first direction Y and the second direction X are not in the same direction. For ease of explanation and understanding, this embodiment uses the example of the first direction Y and the second direction X being perpendicular to each other. In specific applications, the angle between the first direction Y and the second direction X can be adjusted according to actual needs and application scenarios. This embodiment does not limit this.

[0053] In some embodiments, the solar cell includes a front passivation layer 134, which is located on a first surface (front side) and is considered as a front passivation layer. The front passivation layer 134 can be a single-layer structure or a stacked structure, and the material of the front passivation layer 134 can be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0054] In some embodiments, the substrate 100 includes two opposing first edges 101 and two opposing second edges 102. The junction of the first edge 101 and the second edge 102 has a chamfer 103. The chamfer 103 is formed because, in conventional solar cells, due to the limitations of the monocrystalline silicon refining process for preparing the substrate, monocrystalline silicon rods can currently only be made into round shapes. After the silicon rod is produced, it is sliced, which means cutting the cross-section of the silicon rod into the shape of a monocrystalline silicon wafer (the area is calculated so that the illumination area can be maximized within a unit, the silicon rod material can be saved to the maximum extent, and it is also convenient for the production of cells and modules). Chamfers are often set at the junctions of the various boundaries of the substrate to reduce the external stress of the silicon wafer and avoid micro-damage to the edges and corners of the silicon wafer.

[0055] In some embodiments, the first gate line 11 is either a positive gate line or a negative gate line, and the second gate line 12 is either a positive gate line or a negative gate line.

[0056] Continue to refer to Figure 1 Multiple first grid lines 11 are electrically connected via a first main grid connection line 1051; multiple second grid lines 12 are electrically connected via a second main grid connection line 1041. The first main grid connection line 1051 has a first connection pad 1052, and the second main grid connection line 1041 has a second connection pad 1042. The first connection pad 1052 and the second connection pad 1042 are respectively used for welding to the solder strips of the photovoltaic module to achieve connection between cells and form a cell string. The first main grid connection line 1052 and the first connection pad 1051 together constitute a first connection structure 105. The second main grid connection line 1041 and the second connection pad 1042 together constitute a second connection structure 104.

[0057] It should be noted that the main grid connection line here is not a traditional main grid, but rather a bridge connecting each sub-grid. The solder strip is connected through the first and second connecting pads to collect current. In this way, the width of the main grid connection line can be set to be thinner, reducing the effective shading area and reducing resistance loss, thereby increasing the total power of the module. The main grid connection lines can also be set more densely, shortening the path of current through the fine grid, thereby improving the photoelectric conversion efficiency of the solar cell.

[0058] In some embodiments, the back-contact solar cell does not have a first main grid connection line and a second main grid connection line. Multiple first grid lines 11 and multiple second grid lines 12 are soldered to each other via small pads and solder ribbons. This eliminates the conventional steps of creating main grid lines and main grid connection lines, reducing the fabrication cost of the main grid lines and minimizing shading, thereby improving the photoelectric conversion efficiency of the solar cell.

[0059] In some embodiments, the back-contact solar cell includes an edge connection line 13 and a first pad 14, with the edge connection line 13 close to the first edge 101. The first distance between the first pad 14 and the first edge 101 is greater than the second distance between the edge connection line 13 and the first edge 101. Thus, the distance between the edge connection line 13 and the first pad 14 can avoid the risks associated with microcracks and micro-cracks in the silicon wafer. Specifically, by placing the edge connection line 13 at the edge of the solar cell where there is a risk of microcracks and micro-cracks, the current collection capability at the edge is improved, and the path for current collection or conduction is optimized.

[0060] It should be noted that for solar cells with main grid connection lines, edge connection lines 13 are part of the main grid connection lines. This is just a further explanation of the main grid connection lines near the first edge 101, and there is no additional setting explanation.

[0061] The corresponding edge connection line 13 can be either a positive or negative main gate connection line, depending on the polarity of the connected first gate line 11 and second gate line 12. Therefore, in some embodiments, if the number of main gate connection lines is even, one edge connection line 13 is electrically contacted with the plurality of first gate lines 11 arranged along the first direction, and the other edge connection line 13 is electrically contacted with the plurality of second gate lines 12 arranged along the first direction. If the number of main gate connection lines is odd, two main gate connection lines are electrically contacted with the plurality of first gate lines 11 arranged along the first direction, respectively. An example is given where the number of main gate connection lines is even.

[0062] refer to Figure 3 The portion of the first gate line 11 adjacent to the first pad 14 includes a first gate line segment 111 and a second gate line segment 112 spaced apart. The first gate line segment 111 is electrically connected to the edge connection line 13, and the second gate line segment 112 is electrically connected to the first pad 14. In this way, the disconnected first gate line 11, namely the first gate line segment 111 and the second gate line segment 112, can be connected to the nearest connection part, thereby avoiding more path loss and improving photoelectric conversion efficiency.

[0063] In some embodiments, the first grid segment 111 and the second grid segment 112 may be printed from the same printing material, and may be separated into the first grid segment 111 and the second grid segment 112 during screen printing.

[0064] In some embodiments, the first grid line segment 111 and the second grid line segment 112 are a single long grid line during screen printing, which is then segmented after subsequent processing and defined as the first grid line segment 111 and the second grid line segment 112.

[0065] In some embodiments, a first gap region is provided between the first gate segment 111 and the second gate segment 112. The first gap region refers to a region without gate segments, but does not mean that there are no doped regions below it. The first gap region allows the first connecting gate line 123, which is electrically connected to the third gate segment 121, to pass through, thereby preventing short circuits between the first gate segment 111 and the third gate segment 121 or between the second gate segment 112 and the third gate segment 121.

[0066] In some embodiments, the first gate line segment 111 and the second gate line segment 112 are not spaced apart, and the first gate line segment 111 and the second gate line segment 112 are a connected gate line, and an insulating layer is provided in the area through which the first connected gate line 123 passes.

[0067] In some embodiments, a portion of the second gate line segment 112 is directly electrically connected to the first pad 14, and a portion of the second gate line segment 112 is electrically connected to the first pad 14 through a connecting segment.

[0068] Continue to refer to Figure 3 In some embodiments, the portion of the second gate line 12 adjacent to the first pad 14 includes a third gate line segment 121; a first connecting gate line 123 electrically connects m third gate line segments 121, where m ≥ 3. By setting the first connecting gate line 123 and electrically connecting it to multiple third gate line segments 121, the area of ​​the first pad 14 can be larger within a limited area, thus facilitating solder ribbon alignment; the areas of the first gate line 11 and the second gate line 12 can be larger, thus collecting more current and achieving a higher photoelectric conversion efficiency.

[0069] In some embodiments, the portion of the second gate line 12 adjacent to the first pad 14 includes a third gate line segment 121 and a fourth gate line segment 122 spaced apart. The second gate line 12 electrically connected to the first connecting gate line 123 is the third gate line segment 121, and the second gate line 12 not electrically connected to the first connecting gate line 123 is the fourth gate line segment 122. Figure 3 The third gate segment 121 includes two types: a long gate segment and a short gate segment.

[0070] The third grid segment 121 and the fourth grid segment 122 are spaced apart. The third grid segment 121 and the fourth grid segment 122 can be printed from the same printing material, and are separated into the third grid segment 121 and the fourth grid segment 122 during screen printing.

[0071] In some embodiments, the third grid line segment 121 and the fourth grid line segment 122 are a single long grid line during screen printing, which is then segmented after subsequent processing and defined as the third grid line segment 121 and the fourth grid line segment 122.

[0072] In some embodiments, a second gap region is provided between the third gate segment 121 and the fourth gate segment 122. The second gap region refers to a region without gate segments and does not mean that there are no doped regions below it. The second gap region is used to set the first pad 14.

[0073] In some embodiments, reference Figure 3 A broken third gate segment 121 corresponds to a fourth gate segment 122. In some embodiments, reference... Figure 4 The portion of the second gate line 12 adjacent to the first pad 14 includes spaced-apart third gate line segments 121 and fourth gate line segments 122, the number of fourth gate line segments 122 being less than or equal to the number of third gate line segments 121. That is, one disconnected fourth gate line segment 122 can correspond to multiple third gate line segments 121, and the distance between adjacent third gate line segments 121 is less than or equal to the distance between adjacent third gate line segments 121. In this way, more third gate line segments 121 can be provided for current collection, improving photoelectric conversion efficiency.

[0074] In some embodiments, reference Figure 4 Along the first direction, there are m1 third grid segments 121 between adjacent first grid lines 11, where m1 ≥ 2. That is, there are multiple disconnected third grid segments 121 between adjacent first grid lines 11, forming a dense grid for collecting current. The number of m1 can be 2, 3, 4, 5, 6, 7, or 8, or any value between any two numbers.

[0075] In some embodiments, the m1 third gate line segments 121 between adjacent first gate lines 11 can be arranged at intervals or staggered. In some embodiments, the distance between any two adjacent third gate line segments 121 can be the same or different.

[0076] In some embodiments, the first width of the third gate segment 121 along the first direction Y is less than or equal to the second width of the fourth gate segment 122 along the first direction Y. Thus, by providing a larger number of third gate segments 121 and increasing the spacing between adjacent third gate segments 121, the larger number of third gate segments 121 located near the edge of the solar cell can collect more current, thereby improving the photoelectric conversion efficiency.

[0077] In some embodiments, the ratio of the first width to the second width can be 0.75 to 1. Specifically, it can be 0.75, 0.8, 0.85, 0.9, 0.95, or 1, or a range between any two numbers.

[0078] In some embodiments, the system further includes: a pad connection line 15, the two ends of which are respectively connected to an edge connection line 13 and a first pad 14.

[0079] In some embodiments, the width of the pad connection line 15 along the first direction Y is greater than the width of the first gate line 11 along the first direction Y, and the width of the pad connection line 15 along the first direction is greater than the width of the second gate line 12 along the first direction. Setting the width of the pad connection line 15 to be wider can reduce resistance and reduce electrical losses.

[0080] In some embodiments, reference Figure 4 The first spacing d1 between the third gate segment 121 and the pad connection line 15 is greater than or equal to the second spacing d2 between the third gate segment 121 and the first gate segment 111. Thus, for the pad connection line 15, which carries a large current, a larger first spacing d1 can reduce heat radiation caused by the large current transmission, thereby improving the yield of the third gate segment 121. Furthermore, it can prevent deformation of the third gate segment 121 and the pad connection line 15 caused by heat radiation, and even avoid short circuits between the third gate segment 121 and the pad connection line 15, effectively improving the yield of the photovoltaic module.

[0081] In some embodiments, the third gate segment 121 includes m2 first-type gate segments and m3 second-type gate segments, the first-type gate segments and the second-type gate segments being located on opposite sides of the pad connection line 15 along the first direction, where m2 ≠ m3. For example, Figure 3 In this design, there are three first-type gate segments and four second-type gate segments. By using two different numbers of third gate segments 121, the connection between the first pad 14 and the pad connection line 15 is not centered. This concentrates the stress during soldering near the center line of the first pad 14. A buffer zone can be reserved in the soldering area of ​​the first pad 14, distributing the stress generated during soldering more evenly over a wider area of ​​the pad rather than at the edges, thus reducing the risk of the pad lifting, breaking, or detaching from the silicon wafer due to stress. Secondly, the non-centered design itself includes a certain alignment tolerance. As long as the solder ribbon falls within the effective contact area of ​​the pad, even if it is not perfectly centered, a good electrical connection can be guaranteed. This increases production speed, reduces equipment precision requirements, and thus improves overall yield.

[0082] In some embodiments, reference Figure 5The substrate 100 also has a second edge 102 adjacent to the first edge 101; it further includes: a second pad 24 near the second edge 102, and a portion of the second gate line 12 adjacent to the second pad 24 including a fifth gate line segment 125; and a second connecting gate line 124 electrically connecting n fifth gate line segments, where n≥3 and m≤n. Thus, by providing the second pad 24, the second connecting gate line 124, and the fifth gate line segment 125 at the edge of the solar cell, the spacing area can be reduced, resulting in a larger area for current collection and thus improving battery efficiency.

[0083] In some embodiments, the width of the second connecting gate line 124 is greater than the width of the first connecting gate line 123. The width of the connecting gate line near the chamfer 103 or the second edge 102 is set to be larger, so that the solder ribbon has a smaller current path when it is in the collection area of ​​the connecting edge, thereby reducing electrical losses.

[0084] In some embodiments, the first solder pad 14 and the second solder pad 24 may be the same size or different. Setting the size of the second solder pad 24 to be larger than the size of the first solder pad 14 can reduce the welding difficulty of the solder joint and increase the welding strength of the joint, thereby improving the yield of the photovoltaic module.

[0085] In some embodiments, the distance between the second connecting gate line 124 and the second pad 24, the distance between the second connecting gate line 124 and the adjacent first gate line 11, the spacing between the fifth gate line segments 125, the number of the fifth gate line segments 125, and the spacing between the fifth gate line segments 125 and the pad connection line 15 can refer to the relevant content of the distance between the first connecting gate line 123 and the first pad 14, the distance between the first connecting gate line 123 and the adjacent first gate line 11, the spacing between the third gate line segments 121, the number of the third gate line segments 121, and the spacing between the third gate line segments 121 and the pad connection line 15, and will not be repeated here.

[0086] refer to Figure 6 The substrate also has a second edge 102 adjacent to the first edge 101, a first pad 14 near the second edge 102, and a third grid line segment 121 near the second edge 102. The back contact solar cell also has a third pad for the PAD point of the main grid line electrically connected to the adjacent first grid line 11.

[0087] By setting the first pad 14 in the area of ​​the second edge 102, and then setting a portion of the first gate line 11 as a gate line segment and a portion of the second gate line segment 112 as a third gate line segment 121, and achieving electrical connection between the second gate lines 12 through a long third gate line segment 121, the number of short gate line segments can be reduced, thereby increasing the area for collecting current and thus improving battery efficiency.

[0088] In some embodiments, the second gate line 12 further includes an edge gate line 126 located between the third gate line segment 121 and the second edge 102. The first connecting gate line 123 electrically connects c edge gate lines 126, where c ≥ 1. The edge gate line 126 can be a conventional second gate line 12, i.e., opposite to two first pads 14. The edge gate line 126 can also be a long gate line, opposite to multiple first pads 14. The edge gate line enables pathways between multiple main gate connection lines electrically connected to the second gate line 12, thereby improving the yield of the photovoltaic module.

[0089] The back-contact solar cell provided in this application embodiment, by setting an edge connection line 13 and a first pad 14, wherein the first distance between the first pad 14 and the first edge 101 is greater than the second distance between the edge connection line 13 and the first edge 101, allows the edge connection line 13 to collect the current between the first grid line 11 and the second grid line 12, and the first pad 14, which is soldered to the solder ribbon, is far from the first edge 101, thereby preventing the problem of cracking that occurs during cell soldering, and thus improving the yield of the cell. The portion of the first gate line 11 adjacent to the first pad 14 includes a first gate line segment 111 and a second gate line segment 112 spaced apart. The first gate line segment 111 is electrically connected to the edge connecting line 13, and the second gate line segment 112 is electrically connected to the first pad 14. The portion of the second gate line 12 adjacent to the first pad 14 includes a third gate line segment 121. A first connecting gate line 123 is electrically connected to m third gate line segments 121, where m ≥ 3. By setting the first connecting gate line 123 and electrically connecting it to multiple third gate line segments 121, the area of ​​the first pad 14 can be larger within a limited area, thus facilitating solder ribbon alignment. The areas of the first gate line 11 and the second gate line 12 are also larger, thus collecting more current and achieving a higher photoelectric conversion efficiency.

[0090] Figure 7 This is a schematic diagram of a stacked battery provided in another embodiment of this application.

[0091] refer to Figure 7 The tandem solar cell includes: a bottom cell 10, which is a back-contact solar cell as described in any of the above embodiments; and a perovskite cell 180, which is located on the bottom cell 10.

[0092] The tandem solar cell can be an ABC Tandem solar cell (All-Back-Contact Perovskite / Silicon Tandem solar cell).

[0093] In some embodiments, the tandem solar cell has a first grid line 186 of a first polarity and a second grid line of a second polarity. The first grid line 186 is in electrical contact with the perovskite solar cell 180, and the second grid line is in electrical contact with the bottom solar cell 10. The second grid line serves as an electrode of the bottom solar cell.

[0094] In some embodiments, an interface layer 181 is provided between the top battery and the bottom battery.

[0095] It is worth noting that the stacked battery in this application embodiment only illustrates two layers of solar cells. Those skilled in the art can set up three layers of solar cells or more than three layers of multi-layer stacked solar cells according to actual needs.

[0096] The mainstream methods for tandem solar cells are the 2T (two-terminal series / two-terminal stacked) structure and the 4T (four-terminal series / four-terminal stacked) structure; there is also the 3T structure, which is mainly used for three-terminal tandem solar cells made by combining BC cells with perovskites, but it will produce three electrodes.

[0097] The two sub-cells of the four-terminal stacked cell are made independently, and they are only connected optically. Their circuits are independent of each other. It can be understood that the perovskite and crystalline silicon cells are just physically stacked, but in reality they still do their own thing and output independently. Therefore, the four-terminal stacked cell will have two positive electrodes and two negative electrodes.

[0098] In some embodiments, the perovskite solar cell 180 includes: a first transport layer 182, a perovskite substrate 183, a second transport layer 184, a first transparent conductive layer 185, and an antireflection layer (not shown). The first transport layer is directly opposite the bottom cell.

[0099] In some embodiments, the first transport layer may be either an electron transport layer or a hole transport layer, and the second transport layer may be either an electron transport layer or a hole transport layer.

[0100] Figure 8 This is a schematic diagram of a photovoltaic module provided in another embodiment of this application.

[0101] It should be noted that, Figure 7The photovoltaic module shown only depicts four back-contact solar cells 20, with each pair of back-contact solar cells 20 electrically connected via connecting members 28. However, in practice, a photovoltaic module can include multiple cell strings, which can be connected in series or in parallel. Each cell string includes multiple back-contact solar cells 20 connected via connecting members 28. Furthermore, since the back-contact solar cells 20 are back-contact cells, Figure 7 The diagram illustrates a connecting component 28 of a conductive type. There is also another connecting component 28 electrically connecting the two middle back-contact solar cells 20. Figure 7 It was not indicated.

[0102] refer to Figure 8 The photovoltaic module includes: a battery string, which is formed by connecting multiple back-contact solar cells 20 as described in any of the above embodiments, or back-contact solar cells 20 prepared by any of the above embodiments, or stacked cells as described in the above embodiments; an encapsulating film 21 for covering the surface of the battery string; and a cover plate 22 for covering the surface of the encapsulating film 21 away from the battery string.

[0103] Specifically, in some embodiments, multiple battery cells can be electrically connected to each other via a connecting member 28, which is electrically connected to a sub-grid on the battery cell. The sub-grid includes a second grid line 12 and a first grid line. 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 one or more organic encapsulating films such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene elastomer (POE) film, or polyethylene terephthalate (PET) film. For example, the encapsulating layer composed of multiple organic encapsulating films can be an EPE film, which is an EVA-POE-EVA three-layer composite film.

[0104] It is worth noting that the first encapsulation layer and the second encapsulation layer still have a dividing 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.

[0105] 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, 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; or the first cover plate being opposite to one side of the solar cell and the second cover plate being opposite to the other side of the solar cell.

[0106] Those skilled in the art will understand that the above-described embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of this application. Any person skilled in the art can make their own modifications and alterations 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 solar cell, characterized in that, include: A substrate having a first edge; The first grid lines and the second grid lines are arranged at intervals along the first direction; An edge connection line and a first pad, wherein the edge connection line is close to the first edge; a first distance between the first pad and the first edge is greater than a second distance between the edge connection line and the first edge; Wherein, the portion of the first gate line adjacent to the first pad includes a first gate line segment and a second gate line segment spaced apart, the first gate line segment being electrically connected to the edge connection line, and the second gate line segment being electrically connected to the first pad; The portion of the second gate line adjacent to the first pad includes a third gate line segment; A first connecting gate line electrically connects m of the third gate line segments, where m ≥ 3.

2. The back-contact solar cell according to claim 1, characterized in that, The portion of the second gate line adjacent to the first pad includes the third gate line segment and the fourth gate line segment spaced apart, wherein the number of the fourth gate line segment is less than or equal to the number of the third gate line segment.

3. The back-contact solar cell according to claim 2, characterized in that, Along the first direction, there are m1 third gate line segments between adjacent first gate lines, where m1 ≥ 2.

4. The back-contact solar cell according to claim 2, characterized in that, The first width of the third gate segment along the first direction is less than or equal to the second width of the fourth gate segment along the first direction.

5. The back-contact solar cell according to claim 1, characterized in that, Also includes: The pad connection line has its two ends connected to the edge connection line and the first pad, respectively; the first spacing between the third gate line segment and the pad connection line is greater than or equal to the second spacing between the third gate line segment and the first gate line segment.

6. The back-contact solar cell according to claim 5, characterized in that, The third gate segment includes m2 first-type gate segments and m3 second-type gate segments. The first-type gate segments and the second-type gate segments are located on both sides of the pad connection line along the first direction, and m2 ≠ m3.

7. The back-contact solar cell according to claim 1, characterized in that, The substrate also has a second edge adjacent to the first edge; it further includes: a second pad close to the second edge, the portion of the second gate line adjacent to the second pad including a fifth gate line segment; and a second connecting gate line electrically connecting n of the fifth gate line segments, where n≥3 and m≤n.

8. The back-contact solar cell according to claim 1, characterized in that, The substrate also has a second edge adjacent to the first edge, the first pad is close to the second edge, and the third gate segment is close to the second edge.

9. The back-contact solar cell according to claim 8, characterized in that, The second gate line also includes an edge gate line located between the third gate line segment and the second edge, and the first connecting gate line electrically connects c of the edge gate lines, where c ≥ 1.

10. A stacked battery, characterized in that, include: The bottom battery is a back-contact solar cell as described in any one of claims 1 to 9; A perovskite solar cell, wherein the perovskite solar cell is located on one side of the bottom solar cell.

11. A photovoltaic module, characterized in that, include: A battery string is formed by connecting multiple back-contact solar cells as described in any one of claims 1 to 9 or stacked cells as described in claim 10; An encapsulating film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

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