Solar cell and its manufacturing method, stacked cell, photovoltaic assembly

Abstract

The present invention provides solar cells, methods for manufacturing the same, stacked cells, and photovoltaic power generation assemblies. [Solution] The solar cell includes a cell substrate having a first surface and a second surface facing away from each other, and a plurality of grid lines located on the first surface and / or the second surface and arranged at intervals in the first direction, which are electrically connected to the cell substrate and include a contact structure and a connecting layer, wherein the contact structure includes a plurality of contact portions, and the connecting layer is a long structure extending in the second direction, wherein the contact portions include first contact portions and second contact portions arranged alternately in the second direction, and the connecting layer has first side portions and second side portions facing away from each other in the first direction, wherein the first contact portions are connected in contact with at least the first side portions and the second contact portions are connected in contact with the second side portions, or the second contact portions are connected in contact with at least the second side portions and the first contact portions are connected in contact with the first side portions.

Description

Technical Field

[0001] The present disclosure relates to the field of photovoltaic power generation, and particularly to solar cells and their manufacturing methods, stack cells, and photovoltaic power generation assemblies.

Background Art

[0002] As fossil resources are gradually depleted, solar cells are being increasingly widely used as a new alternative energy. A solar cell is a device that converts solar light energy into electrical energy. By using the photovoltaic effect principle, a solar cell can generate carriers and then efficiently utilize the electrical energy by extracting the carriers using grid lines. Current solar cells mainly include BC cells (Back Contact cells), TOPCON (Tunnel Oxide Passivated Contact) cells, PERC cells (Passivated emitter and real cell), and heterojunction cells.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Embodiments of the present disclosure provide a solar cell and its manufacturing method, a stack cell, and a photovoltaic power generation assembly, which can at least improve the electrical connection performance between the grid lines and the cell substrate and reduce the manufacturing cost of the grid lines.

Means for Solving the Problems

[0004] According to some embodiments of the present disclosure, one embodiment of the embodiments of the present disclosure provides a solar cell comprising a cell substrate having a first surface and a second surface facing each other in the thickness direction, and a plurality of grid lines located on the first surface and / or the second surface and spaced apart in a first direction, comprising a contact structure and a connecting layer electrically connected to the cell substrate, wherein the contact structure comprises a plurality of contact portions sequentially arranged in a second direction intersecting the first direction, and the connecting layer is an elongated structure extending in the second direction, wherein the connecting layer is in contact with a plurality of the contact portions of the contact structure. The contact portion and the connecting layer are made of different materials, and their orthographic projections onto the cell substrate partially overlap. The contact portion includes a first contact portion and a second contact portion arranged alternately in the second direction, and the connecting layer has a first side portion and a second side portion facing away from each other in the first direction. The first contact portion is connected in contact with at least the first side portion, and the second contact portion is connected in contact with the second side portion, or the second contact portion is connected in contact with at least the second side portion, and the first contact portion is connected in contact with the first side portion.

[0005] In some embodiments, the first contact portion and the second contact portion are not facing each other in the second direction on the same grid line.

[0006] In some embodiments, on the same grid line, a portion of the first contact portion and a portion of the second contact portion face each other in the second direction.

[0007] In some embodiments, in the second direction, the portion of the first contact portion facing the second contact portion is the first portion, and the width of the portion of the first contact portion other than the first portion in the first direction is 25 μm or less.

[0008] In some embodiments, the orthographic projection of the contact portion onto the cell substrate in the thickness direction is circular, elliptical, triangular, rectangular, trapezoidal, or N-sided, where N is a positive integer greater than 4.

[0009] In some embodiments, the orthographic projection shape of the contact portion onto the cell substrate is circular or elliptical in the thickness direction, and adjacent first and second contact portions are in contact in the second direction.

[0010] In some embodiments, the orthographic projection area of ​​the contact portion onto the cell substrate in the thickness direction is 100 μm² to 5000 μm².

[0011] In some embodiments, the width of the connecting layer in the first direction is 10 μm to 70 μm.

[0012] In some embodiments, of the adjacent first and second contact portions in the second direction, the edge of the first contact portion closest to the second contact portion is the first edge, the edge of the second contact portion closest to the first contact portion is the second edge, and the distance between the first and second edges is 200 μm or less.

[0013] In some embodiments, the thickness of the contact portion in the thickness direction is 1 μm to 10 μm, and / or the thickness of the connecting layer is 4 μm to 20 μm.

[0014] In some embodiments, the grid line is either an ultrafine grid or a main grid, and the other of the ultrafine grid or the main grid is a long structure extending in the first direction.

[0015] In some embodiments, the grid lines are an ultrafine grid, and the solar cell includes a plurality of main grids located on at least one of the first and second surfaces and spaced apart in the second direction, and comprising a connection structure and an interconnection layer electrically connected to the cell substrate, wherein the connection structure comprises a plurality of connection portions arranged sequentially in the first direction, and the interconnection layer comprises a long structure extending in the first direction, the interconnection layer is connected in contact with a plurality of the connection portions of the connection structure, the connection portions comprise first and second connection portions arranged alternately in the second direction, the interconnection layer has third and fourth sides facing each other in the first direction, the first connection portions are connected in contact with at least the third side portions, the second connection portions are connected in contact with at least the fourth side portions, and the materials of the connection portions and the materials of the interconnection layer are different.

[0016] In some embodiments, the material of the contact portion includes silver particles, and the material of the connecting layer includes copper particles or silver-plated copper particles.

[0017] In some embodiments, the diameter of the copper particles is 50 nm to 1500 nm, or the diameter of the silver-plated copper particles is 1 μm to 10 μm, or the proportion of silver in the silver-plated copper particles is 15% to 50%.

[0018] According to some embodiments of the present disclosure, another embodiment of the embodiments of the present disclosure further provides a method for manufacturing a solar cell, the method for manufacturing a solar cell comprising the steps of: providing a cell substrate having a first surface and a second surface facing opposite directions in the thickness direction; forming a plurality of grid lines spaced apart in a first direction on the first surface and / or the second surface, wherein the grid lines include contact structures and connecting layers electrically connected to the cell substrate, the contact structures include a plurality of contact portions sequentially arranged in a second direction intersecting the first direction, and the connecting layer is an elongated structure extending in the second direction, wherein the connecting layer comprises a plurality of the contact structures The connection layer is connected in contact with the contact portion, the contact portion and the connection layer are made of different materials, and the orthographic projections of both onto the cell substrate partially overlap, the contact portion includes a first contact portion and a second contact portion arranged alternately in the second direction, the connection layer has a first side portion and a second side portion facing away from each other in the first direction, the first contact portion is connected in contact with at least the first side portion and the second contact portion is connected in contact with the second side portion, or the second contact portion is connected in contact with at least the second side portion and the first contact portion is connected in contact with the first side portion.

[0019] In some embodiments, the grid lines are an ultrafine grid, the second surface has a first printing area and a second printing area that at least partially overlaps the first printing area, and the step of forming the grid lines includes the steps of printing a first paste onto the first printing area using a first screen printing process, performing a sintering treatment on the first paste to form the contact structure corresponding to the first printing area, printing a second paste onto the second surface using a second screen printing process, and performing a curing treatment on the second paste to form the connecting layer corresponding to the second printing area, wherein the first paste is a burn-through type paste, the second paste is a non-burn-through type paste, and the process temperature of the sintering treatment is greater than the process temperature of the curing treatment.

[0020] In some embodiments, the first paste is a silver paste, and the second paste is a copper paste or a silver-plated copper paste.

[0021] In some examples, the solid content in the silver paste is 75% to 92%.

[0022] In some embodiments, the second surface further includes a third printing area, and in the step of performing the first screen printing process, the first paste is further printed on the third printing area, and in the step of performing the sintering process, a main grid corresponding to the third printing area is further formed, or in the step of performing the second screen printing process, the second paste is further printed on the third printing area, and in the step of performing the curing process, a main grid corresponding to the third printing area is further formed.

[0023] In some embodiments, the ultrafine grid formed on the second surface is a back ultrafine grid, the main grid formed on the second surface is a back main grid, the first surface has a fourth printing region extending in the first direction and a fifth printing region extending in the second direction, and before the sintering process, the method for manufacturing the solar cell further includes the steps of printing a third paste on the fourth printing region using a third screen printing process, performing the sintering process, further performing the sintering process on the third paste to form a front ultrafine grid corresponding to the fourth printing region, printing a fourth paste on the fifth printing region using a fourth screen printing process, and performing the sintering process, further performing the sintering process on the fourth paste to form a front main grid corresponding to the fifth printing region.

[0024] According to some embodiments of the present disclosure, another aspect of the embodiments of the present disclosure further provides a stacked cell, and the stacked cell includes a bottom cell that is a solar cell described in any one of the above items, or a solar cell manufactured by the method for manufacturing a solar cell described in any one of the above items, and a top cell located on one side of the bottom cell.

[0025] According to some embodiments of the present disclosure, still another aspect of the embodiments of the present disclosure further provides a photovoltaic assembly, and the photovoltaic assembly includes a cell string formed by connecting a plurality of solar cells described in any one of the above items, or a plurality of solar cells manufactured by the method for manufacturing a solar cell described in any one of the above items, or a plurality of the above stacked cells, a sealing film covering the surface of the cell string, and a cover plate covering the surface of the sealing film away from the cell string.

[0026] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages.

[0027] The first contact portion is in contact with and connected to at least the first side portion, and the second contact portion is in contact with and connected to the second side portion, or the second contact portion is in contact with and connected to at least the second side portion, and the first contact portion is in contact with and connected to the first side portion. By designing in this way, the first contact portion and the second contact portion adjacent in the second direction can be arranged so as to be displaced in the first direction. Thus, on the premise that the size of the connection layer is the same, compared with manufacturing a contact structure having a long-shaped structure similar to the connection layer, the first contact portion and the second contact portion arranged in a displaced manner can ensure that the contact structure and the connection layer have a sufficient contact area while reducing the amount of material required for the contact structure. As a result, the performance of the electrical connection between the grid line and the cell substrate can be improved, and the manufacturing cost of the grid line can be reduced. On the other hand, the first contact portion and the second contact portion arranged in a displaced manner can widen the distance between the two outermost edges in the first direction of both the first contact portion and the second contact portion. Therefore, on the premise that the size of the connection layer is the same, compared with manufacturing a contact structure having a long-shaped structure similar to the connection layer, the requirement for the alignment accuracy between the connection layer and the contact structure can be reduced. Thereby, while ensuring a high contact performance between the contact structure and the connection layer, the manufacturing difficulty of the connection layer and the manufacturing difficulty of the grid line can be reduced.

[0028] Also, by designing such that the material of the contact portion is different from the material of the connection layer, and adjusting the costs of the material of the contact portion and the material of the connection layer, the manufacturing cost of the contact structure can be further reduced.

Brief Description of the Drawings

[0029] One or more embodiments are illustrated by corresponding images in the drawings, and these illustrative descriptions do not constitute limitations on the embodiments, and unless otherwise specified, the images in the drawings do not constitute limitations on proportion. To better illustrate the embodiments of the disclosure or the technical solutions of the prior art, the drawings required for the embodiments are briefly described below. It is clear that the accompanying drawings in the following description represent only some embodiments of the disclosure, and those skilled in the art can obtain other drawings based on these drawings without requiring any creative effort. [Figure 1] This is a first partial schematic plan view of the grid lines in a solar cell provided by one embodiment of the present disclosure. [Figure 2] This is a partially schematic plan view of a solar cell provided by one embodiment of the present disclosure. [Figure 3] This is a schematic cross-sectional view along the first cross-sectional direction AA1 in Figure 2. [Figure 4] This is a second partial schematic plan view of the grid lines in a solar cell provided by one embodiment of the present disclosure. [Figure 5] This is a third partial schematic plan view of the grid lines in a solar cell provided by one embodiment of the present disclosure. [Figure 6] This is a fourth partial schematic plan view of the grid lines in a solar cell provided by one embodiment of the present disclosure. [Figure 7] This is a fifth partial schematic plan view of the grid lines in a solar cell provided by one embodiment of the present disclosure. [Figure 8] This is a partially schematic enlarged view of two adjacent contact portions in a solar cell provided by one embodiment of the present disclosure. [Figure 9] This is a sixth partial schematic plan view of the grid lines in a solar cell provided by one embodiment of the present disclosure. [Figure 10] This is a seventh partial schematic plan view of the grid lines in a solar cell provided by one embodiment of the present disclosure. [Figure 11] This is a schematic plan view of the grid lines of a solar cell provided by one embodiment of the present disclosure. [Figure 12] This is another schematic plan view of a solar cell provided by one embodiment of the present disclosure. [Figure 13] This is a partially schematic plan view of the main grid in a solar cell provided by one embodiment of the present disclosure. [Figure 14] This is a partial schematic cross-sectional view of a stack cell provided in another embodiment of the present disclosure. [Figure 15] This is a partial schematic perspective view of a cell string in a photovoltaic assembly provided in yet another embodiment of the present disclosure. [Figure 16] This is a partial schematic cross-sectional view of a photovoltaic assembly provided in yet another embodiment of the present disclosure. [Modes for carrying out the invention]

[0030] As the analysis reveals, whether it's a solar cell with grid lines on both sides or a back-contact battery with grid lines on one side, the process of printing silver paste to form the grid lines involves a large amount of silver paste, high metallization costs, and a need to reduce the manufacturing costs of the grid lines. Furthermore, back-contact batteries with grid lines on one side use more silver paste than solar cells with grid lines on both sides.

[0031] In actual applications, for solar cells with grid lines on both sides, such as TOPCON cells, the total amount of silver paste used in the solar cell is 80 mg, and the amount of silver paste used on one side is up to 40 mg.

[0032] Embodiments of this disclosure provide a solar cell, a method for manufacturing the same, a stack cell, and a photovoltaic assembly, wherein the solar cell is designed such that a first contact portion is connected in contact with at least a first side portion and a second contact portion is connected in contact with a second side portion, or a second contact portion is connected in contact with at least a second side portion and a first contact portion is connected in contact with a first side portion, so that adjacent first and second contact portions in a second direction are offset in the first direction. Thus, compared to manufacturing a contact structure that is a long, elongated structure similar to the connection layer, assuming the same size as the connection layer, the offset arrangement of the first and second contact portions ensures sufficient contact area between the contact structure and the connection layer while reducing the amount of material required for the contact structure. This improves the electrical connection performance between the grid lines and the cell substrate and reduces the manufacturing cost of the grid lines. Furthermore, the offset arrangement of the first and second contact portions widens the distance between the two furthest edges in the first direction of both the first and second contact portions. Therefore, compared to manufacturing a contact structure that is a long, elongated structure similar to the connection layer, assuming the same size as the connection layer, the requirements for alignment accuracy between the connection layer and the contact structure are reduced. This ensures high contact performance between the contact structure and the connection layer while reducing the manufacturing difficulty of both the connection layer and the grid lines. In addition, by designing the contact portion material and the connection layer material to be different, the manufacturing cost of the contact structure can be further reduced by adjusting the cost of the materials for the contact portion and the connection layer.

[0033] In the description of the embodiments of this disclosure, the technical terms "first," "second," etc., are used solely to distinguish different subjects and should not be understood as indicating or implying relative importance, or implicitly specifying the number, specific order, or hierarchical relationship of the technical features presented. In the description of the embodiments of this disclosure, unless otherwise clearly and specifically limited, "multiple" means two or more.

[0034] Where the “Examples” are used herein, it is understood that certain features, structures, or properties described in relation to the Examples may be included in at least one of the Examples of this Disclosure. The term “Examples” in each part of this Specification does not necessarily mean the same Example, nor does it mean mutually exclusive, independent, or alternative Examples. Those skilled in the art will understand, both expressly and implicitly, that the Examples described herein may be combined with other Examples.

[0035] In describing the embodiments of this disclosure, the term "and / or" merely describes the relationship between related objects and means that three relationships may exist. For example, in the case of A and / or B, three situations can be described: A exists, A and B exist simultaneously, and B exists. In this specification, the symbol " / " usually indicates that the preceding and following related objects are in an "or" relationship.

[0036] In the description of the embodiments of this disclosure, the term "multiple" means two or more (including two), similarly, "multiple sets" means two or more sets (including two sets), and "multiple sheets" means two or more sheets (including two).

[0037] In the description of the embodiments of this disclosure, the directions or positional relationships indicated by the technical terms "center," "vertical," "horizontal," "length," "width," "thickness," "top," "bottom," "front," "back," "left," "right," "up and down," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" are directions or positional relationships shown based on the drawings and are provided solely for the convenience and simplification of the description of the embodiments of this disclosure. They do not imply or suggest that the devices or elements they refer to necessarily have a specific direction or must be configured or operated in a specific direction, and should not be understood as limitations on the embodiments of this disclosure.

[0038] In the description of the embodiments of this disclosure, unless otherwise explicitly stated and limited, technical terms such as “attached,” “interconnected,” “connected,” and “fixed” should be understood in a broad sense. For example, they may be fixed connections, removable connections, or integrated connections. They may be mechanical connections or electrical connections. They may be direct connections or indirect connections via an intermediate medium, or internal communication between two elements or an interaction relationship between two elements. Those skilled in the art will be able to understand the specific meaning of the above terms in the embodiments of this disclosure depending on the specific circumstances.

[0039] In the drawings corresponding to the embodiments of this disclosure, the thickness and area of ​​the layers are exaggerated for better understanding and explanation. When one component (e.g., a layer, film, region, or substrate) is described as being on or on the surface of another component, that component may be located "directly" on the surface of the other component, and a third component may exist between the two components. Conversely, when one component is described as being formed on the surface of another component, or another component being formed or placed on the surface of one component, it means that there is no third component between these two components. Also, when one component is described as being formed "generally" on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on any part of the edge of the entire surface.

[0040] In the descriptions of the embodiments of this disclosure, when one component “includes” another component, unless otherwise stated, this does not exclude the other component, and it may further include other components. Also, when a component such as a layer, film, region, or plate is said to “be on / located on” another component, it may be “directly” on the other component (i.e., there are no other components between the two components), or other components may be present between them. Furthermore, 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 means that there are no other components between them.

[0041] The terms used in the description of the various embodiments described herein are used solely to describe specific embodiments and are not intended to limit them. As used in the description of each embodiment described and in the appended claims, “the members” includes the plural form unless explicitly indicated in the context. Components include components such as layers, films, regions, or plates.

[0042] Each embodiment of this disclosure will be described in detail below with reference to the drawings. However, those skilled in the art will understand that many technical details are provided in each embodiment of this disclosure to help the reader better understand the embodiments of this disclosure. However, the embodiments of this disclosure can realize the technical proposal for which protection is sought without these technical details or the various changes and modifications based on the embodiments below.

[0043] One embodiment of the present disclosure provides a solar cell, and below, with reference to the drawings, the solar cell provided by one embodiment of the present disclosure will be described in detail.

[0044] Referring to Figures 1 to 7, the solar cell includes a cell substrate 100 having a first surface 110 and a second surface 120 facing each other in the thickness direction Z, and a contact structure 102 and a connecting layer 103 which are located on the first surface 110 and / or the second surface 120 and arranged at intervals in the first direction X, and are electrically connected to the cell substrate 100, the contact structure 102 includes a plurality of contact portions 112 which are sequentially arranged in the second direction Y which intersects the first direction X, the connecting layer 103 includes a plurality of grid lines 101 which are elongated structures extending in the second direction Y, and the connecting layer 103 is a contact The connection layer 103 is connected by contact to multiple contact portions 112 of the structure 102, the contact portions 112 and the connection layer 103 are made of different materials, and their orthographic projections onto the cell substrate 100 partially overlap, the contact portions 112 include first contact portions 122 and second contact portions 132 arranged alternately in a second direction Y, the connection layer 103 has first side portions 113 and second side portions 123 facing each other in a first direction X, the first contact portion 122 is connected by contact to at least the first side portion 113, and the second contact portion 132 is connected by contact to at least the second side portion 123.

[0045] Here, Figure 1 is a first partial schematic plan view of the grid lines in a solar cell provided according to one embodiment of the present disclosure, Figure 2 is a partial schematic plan view of the solar cell provided according to one embodiment of the present disclosure, Figure 3 is a schematic cross-sectional view along the first cross-sectional direction AA1 of Figure 2, Figure 4 is a second partial schematic plan view of the grid lines in a solar cell provided according to one embodiment of the present disclosure, Figure 5 is a third partial schematic plan view of the grid lines in a solar cell provided according to one embodiment of the present disclosure, Figure 6 is a fourth partial schematic plan view of the grid lines in a solar cell provided according to one embodiment of the present disclosure, and Figure 7 is a fifth partial schematic plan view of the grid lines in a solar cell provided according to one embodiment of the present disclosure.

[0046] To clearly show the positional relationship between the connecting layer 103 and the contact portion 112, the connecting layer 103 is depicted in perspective in both Figures 1 and 2. Figure 1 is merely one example of the positional relationship between the connecting layer 103 and the contact portion 112; the positional relationship between the connecting layer 103 and the contact portion 112 will be explained in detail later with reference to other drawings. Figure 3 shows an example where the grid line 101 is located on the second surface 120, but in actual applications, the grid line may be located on the first surface, or on both the first and second surfaces simultaneously.

[0047] In some cases, by referring to Figures 1, 4, 5, or 6, the first contact portion 122 is connected in contact with at least the first side portion 113, and the second contact portion 132 is connected in contact with at least the second side portion 123, so that adjacent first contact portions 122 and second contact portions 132 in the second direction Y are offset in the first direction X. The first contact portion 122 is connected in contact with at least the first side portion 113 and the second contact portion 132 is connected in contact with the second side portion 123, or the second contact portion 132 is connected in contact with at least the second side portion 123 and the first contact portion 122 is connected in contact with the first side portion 113. Later, the positional relationship between the contact portion 112 and the connecting layer 103 of the contact structure 102 will be described in detail.

[0048] Thus, compared to manufacturing a contact structure that is elongated like the connection layer 103, assuming that the size of the connection layer 103 is the same, the offset arrangement of the first contact portion 122 and the second contact portion 132 ensures that the contact structure 102 and the connection layer 103 have a sufficient contact area, while reducing the amount of material required for the contact structure 102. This improves the performance of the electrical connection between the grid line 101 and the cell substrate 100 and reduces the manufacturing cost of the grid line 101. On the other hand, in the first direction X, The first contact portion 122 has a third edge that is separated from the second contact portion 132, and the second contact portion 132 has a fourth edge that is separated from the first contact portion 122. The offset arrangement of the first contact portion 122 and the second contact portion 132 allows for a wider gap between the third edge and the fourth edge in the first direction X. Therefore, compared to manufacturing a contact structure that is elongated like the connecting layer 103, assuming the connecting layer 103 is the same size, the requirements for alignment accuracy between the connecting layer 103 and the contact structure 102 can be reduced. In other words, the offset arrangement of the first contact portion 122 and the second contact portion 132 allows for a larger offset error in the first direction X between the connecting layer 103 and the contact structure 102, and within this offset error, the contact area between the connecting layer 103 and the contact structure 102 does not change. This further ensures high contact performance between the contact structure 102 and the connecting layer 103, and reduces the manufacturing difficulty of the connecting layer 103 and the grid lines 101.

[0049] In some examples, referring to Figures 1, 4, or 5, the first contact portion 122 is connected to at least the first side portion 113 by contact, and the second contact portion 132 is connected to only the second side portion 123 by contact, while the second contact portion 132 does not contact or connect to the first side portion 113.

[0050] In some other examples, referring to Figures 1, 4, or 6, the second contact portion 132 is connected in contact with at least the second side portion 123, and the first contact portion 122 is connected in contact only with the first side portion 113, while the first contact portion 122 does not contact or connect to the second side portion 123.

[0051] In some other cases, referring to Figure 7, it is also possible to design the first contact portion 122 to be connected in contact with at least the first side portion 113 and the second contact portion 132 to be connected in contact with at least the second side portion 123, so that adjacent first contact portions 122 and second contact portions 132 in the second direction Y are spaced apart in the second direction Y, so that the first contact portion 122 is connected in contact with either the first side portion 113 or the second side portion 123, and the second contact portion 132 is connected in contact with either the first side portion 113 or the second side portion 123. Thus, assuming the size of the connecting layer 103 is the same, compared to manufacturing a contact structure that is also elongated like the connecting layer 103, the first contact portion 122 and the second contact portion 132, which are spaced apart in the second direction Y, ensure that the contact structure 102 and the connecting layer 103 have a sufficient contact area, while reducing the amount of material required for the contact structure 102. This improves the performance of the electrical connection between the grid line 101 and the cell substrate 100 and reduces the manufacturing cost of the grid line 101.

[0052] Furthermore, by designing the contact portion 112 and the connecting layer 103 to be made of different materials, it is possible to avoid manufacturing the grid lines 101 from the same material. By adjusting the costs of the materials for the contact portion 112 and the connecting layer 103, for example, by designing the materials so that the cost of the connecting layer 103 is lower than the cost of the contact portion 112, the amount of material required for the contact structure 102 can be reduced by utilizing multiple dispersed contact portions 112, thereby reducing the manufacturing cost of the contact structure 102. In addition, the manufacturing cost of the contact structure 102 can be further reduced by reducing the material cost of the connecting layer 103.

[0053] In some cases, as shown in Figures 1 to 7, for a single grid line 101, the connecting layer 103 may be connected to all contact portions 112 of the contact structure 102 by contact. In actual applications, due to limitations of the printing process, even if the orthographic projection of the connecting layer and all contact portions overlaps on the cell substrate, good contact and connection may not be formed between the connecting layer and any of the contact portions. For example, if there is a large error in the printing thickness of any of the contact portions or a large error in the printing thickness of a part of the connecting layer, or if there is a large difference between the pattern ultimately formed by any of the contact portions and the designed pattern due to limitations of the printing process, good contact and connection may not be formed between the connecting layer and that contact portion.

[0054] In the following sections, a solar cell provided by one embodiment of this disclosure will be described in more detail, accompanied by drawings.

[0055] In some embodiments, referring to Figure 4, the first contact portion 122 and the second contact portion 132 do not face each other in the second direction Y on the same grid line 101. In other words, if the plane perpendicular to the second direction Y is used as the projection plane, the orthographic projections of the first contact portion 122 and the second contact portion 132 onto this projection plane do not overlap.

[0056] In this case, the contact and connection state between the contact portion 112 and the connecting layer 103 is such that the first contact portion 122 is connected by contacting only the first side portion 113, and the second contact portion 132 is connected by contacting only the second side portion 123.

[0057] In some other embodiments, referring to Figures 1, 5, or 6, on the same grid line 101, a portion of the first contact portion 122 and a portion of the second contact portion 132 face each other in the second direction Y. In other words, if the plane perpendicular to the second direction Y is the projection plane, the orthographic projections of the first contact portion 122 and the second contact portion 132 partially overlap on both projection planes.

[0058] Thus, the state of contact and connection between the contact portion 112 and the connecting layer 103 includes at least the following three cases.

[0059] In some cases, referring to Figure 1, the contact and connection state between the contact portion 112 and the connecting layer 103 is such that the first contact portion 122 is connected by contacting only the first side portion 113, and the second contact portion 132 is connected by contacting only the second side portion 123. In order to reduce manufacturing costs by reducing the size of the contact portion 112 itself, and to improve the contact area between the contact portion 112 and the connecting layer 103, the contact portion 112 shown in Figure 1 is made wider in the first direction X and shorter in the second direction Y compared to the contact portion 112 shown in Figure 4, thereby ensuring that more than half of the area of ​​the contact structure 102 can contact and connect with the connecting layer 103 as much as possible.

[0060] In some other cases, referring to Figure 5, the contact and connection state between the contact portion 112 and the connecting layer 103 is such that the first contact portion 122 is connected by contact with the first side portion 113 and also by contact with the second side portion 123, while the second contact portion 132 is connected by contact only with the second side portion 123. In order to reduce the size of the contact portion 112 itself and lower manufacturing costs, and to improve the contact area between the contact portion 112 and the connecting layer 103, the width of the first contact portion 122 in the first direction X is made larger than the width of the second contact portion 132 in the first direction X, thereby ensuring that more than half of the area of ​​the contact structure 102 can be in contact with and connected to the connecting layer 103. Furthermore, compared to the contact portion 112 shown in Figure 1, the contact portion 112 shown in Figure 5 has a larger width in the first direction X and a smaller extension length in the second direction Y, thereby reducing the amount of material required for the contact structure 102 as much as possible.

[0061] In some further cases, referring to Figure 6, the contact and connection state between the contact portion 112 and the connecting layer 103 is such that the first contact portion 122 is connected by contacting only the first side portion 113, and the second contact portion 132 is connected by contacting both the second side portion 123 and the first side portion 113. In order to reduce the size of the contact portion 112 itself and lower manufacturing costs, and to improve the contact area between the contact portion 112 and the connecting layer 103, the width of the second contact portion 132 in the first direction X is made larger than the width of the first contact portion 122 in the first direction X, thereby ensuring that more than half of the area of ​​the contact structure 102 can contact and connect with the connecting layer 103 as much as possible. Furthermore, compared to the contact portion 112 shown in Figure 1, the contact portion 112 shown in Figure 6 has a larger width in the first direction X and a smaller extension length in the second direction Y, thereby reducing the amount of material required for the contact structure 102 as much as possible.

[0062] In the various cases described above, refer to Figure 8, which is a schematic enlarged view of two adjacent contact portions in a solar cell provided by one embodiment of the present disclosure, where in the second direction Y, the portion of the first contact portion 122 facing the second contact portion 132 is the first portion 1221, and the width S of the portion of the first contact portion 122 other than the first portion 1221 in the first direction X is 25 μm or less. In other words, the displacement range between adjacent first contact portion 122 and second contact portion 132 in the second direction Y is 25 μm or less, and may be, for example, 24 μm, 23 μm, 22 μm, 21 μm, 20 μm, 19 μm, 18 μm, 17 μm, 16 μm, 15 μm, 14 μm, 13 μm, 12 μm, 11 μm, 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, or 1 μm.

[0063] Furthermore, the portion of the first contact portion 122 other than the first portion 1221 may be the second portion 1222, and the width S of the second portion 1222 in the first direction X is 25 μm or less. In Figure 8, the first portion 1221 and the second portion 1222 of the first contact portion 122 are separated by a dashed line.

[0064] Assuming that a portion of the first contact portion 122 and a portion of the second contact portion 132 face each other in the second direction Y, if the width S of the second portion 1222 in the first direction X is greater than 25 μm, the degree of misalignment between the adjacent first contact portion 122 and the second contact portion 132 in the first direction X will be large, and the distance between the third edge and the fourth edge in the first direction X will be too large. If the dimensions of the connecting layer 103 are not changed, it will not be possible to guarantee that there is a large contact area between the connecting layer 103 and the contact structure 102. Therefore, by designing the misalignment range between the adjacent first contact portion 122 and the second contact portion 132 in the second direction Y to be 25 μm or less, the degree of misalignment between the adjacent first contact portion 122 and the second contact portion 132 in the first direction X can be appropriately controlled, and the size of the contact portion 112 itself can be made as small as possible while ensuring that more than half of the area of ​​the contact structure 102 can contact and connect with the connecting layer 103.

[0065] In some other embodiments, referring to Figure 7, the first contact portion 122 and the second contact portion 132 are opposite each other in the second direction Y, along the same grid line 101. In other words, if the plane perpendicular to the second direction Y is the projection plane, the orthographic projections of the first contact portion 122 and the second contact portion 132 onto this projection plane overlap. That is, the misalignment range between the adjacent first contact portion 122 and second contact portion 132 in the second direction Y is 0.

[0066] In this case, the contact and connection state between the contact portion 112 and the connecting layer 103 is such that the first contact portion 122 is in contact with and connected to both the first side portion 113 and the second side portion 123, and the second contact portion 132 is in contact with and connected to both the first side portion 113 and the second side portion 123.

[0067] The contact portion 112 will be described in detail below.

[0068] In some embodiments, referring to Figures 1 to 8, the orthographic projection shape of the contact portion 112 onto the cell substrate 100 in the thickness direction Z may be rectangular.

[0069] In some other embodiments, with reference to Figure 9, which is a sixth partial schematic plan view of the grid lines in a solar cell provided in one embodiment of the present disclosure, the orthographic projection shape of the contact portion 112 onto the cell substrate 100 in the thickness direction Z may be circular. Note that, due to the influence of the process precision in forming the contact portion 112, if the orthographic projection shape of the contact portion 112 onto the cell substrate 100 is circular, the circle does not need to be geometrically correct, but may be approximately circular.

[0070] In some other embodiments, with reference to Figure 10, which is a schematic plan view of the seventh portion of the grid lines in a solar cell provided in one embodiment of the present disclosure, the orthographic projection shape of the contact portion 112 onto the cell substrate 100 in the thickness direction Z may be elliptical. Note that if the orthographic projection shape of the contact portion 112 onto the cell substrate 100 is elliptical due to the influence of the process precision in forming the contact portion 112, the circle does not need to be a geometrically correct ellipse, but may be approximately elliptical.

[0071] In some further embodiments, with reference to Figure 11, which is an eighth partial schematic plan view of the grid lines in a solar cell provided by one embodiment of the present disclosure, the orthographic shape of the contact portion 112 onto the cell substrate 100 in the thickness direction Z may be triangular.

[0072] In actual applications, the orthographic projection of the contact portion onto the cell substrate may be a trapezoid or an N-sided polygon, where N is a positive integer greater than 4.

[0073] In some embodiments, referring to Figure 9, the orthographic projection shape of the contact portion 112 onto the cell substrate 100 in the thickness direction Z is circular or elliptical, and adjacent first contact portions 122 and second contact portions 132 are in contact in the second direction Y. Thus, due to the special configuration of the contact portion 112, although some areas of adjacent first contact portions 122 and second contact portions 132 are in contact and connected, most areas are spaced apart in the second direction Y. Assuming that the size of the connecting layer 103 is the same, the amount of material required for the contact structure 102 can be reduced as much as possible.

[0074] Figure 9 shows an example where the orthographic projection of the contact portion 112 onto the cell substrate 100 is circular, and adjacent first contact portions 122 and second contact portions 132 are in contact in the second direction Y. In actual applications, if the orthographic projection of the contact portion onto the cell substrate is circular, adjacent first contact portions and second contact portions in the second direction may be spaced apart from each other.

[0075] Furthermore, if the orthographic projection shape of the contact portion onto the cell substrate is elliptical, adjacent first and second contact portions may be in contact in the second direction. Figure 10 shows only an example where the orthographic projection shape of the contact portion 112 onto the cell substrate 100 is elliptical, and adjacent first and second contact portions 122 and 132 are separated in the second direction Y.

[0076] In some embodiments, referring to Figures 1 to 11, the orthographic projection area of ​​the contact portion 112 onto the cell substrate 100 in the thickness direction Z may be 100 μm² to 5000 μm², for example, 300 μm², 500 μm², 800 μm², 1000 μm², 1200 μm², 1500 μm², 1700 μm², 2000 μm², 2300 μm², 2500 μm², 2800 μm², 3000 μm², 3300 μm², 3500 μm², 3800 μm², 4000 μm², 4200 μm², 4500 μm², or 4800 μm².

[0077] Furthermore, if the orthographic projection area of ​​the contact portion 112 onto the cell substrate 100 is less than 100 μm², the contact area between a single contact portion 112 and the connecting layer 103 is too small, which is detrimental to improving both the electrical connection performance between the contact portion 112 and the cell substrate 100 and the contact performance between the contact portion 112 and the connecting layer 103. If the orthographic projection area of ​​the contact portion 112 onto the cell substrate 100 is larger than 5000 μm², the effect of reducing the amount of material required for the contact structure 102 simply by spacing between adjacent contact portions 112 is limited. Thus, by setting the orthographic projection area of ​​the contact portion 112 onto the cell substrate 100 to 100 μm² to 5000 μm², it is possible to improve the electrical connection performance between the contact portion 112 and the cell substrate 100, improve the contact performance between the contact portion 112 and the connecting layer 103, and reduce the amount of material required for the contact structure 102 as much as possible.

[0078] In some embodiments, referring to Figures 1 to 7, or Figures 9 to 11, the width of the connecting layer 103 in the first direction X may be 10 μm to 70 μm, for example, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, or 65 μm.

[0079] In some cases, referring to Figure 1, in the first direction X, the width of the connecting layer 103 may be substantially the same as the width of the contact portion 112, the difference being that in the second direction Y, multiple contact portions 112 of the contact structure 102 are offset in the first direction X, and the connecting layer 103 is an elongated structure extending in the second direction Y.

[0080] In some embodiments, referring to Figure 8, of the adjacent first contact portion 122 and second contact portion 132 in the second direction Y, the edge of the first contact portion 122 closest to the second contact portion 132 is the first edge portion 122a, and the edge of the second contact portion 132 closest to the first contact portion 122 is the second edge portion 132a, and the distance D between the first edge portion 122a and the second edge portion 132a is 200 μm or less.

[0081] Furthermore, if the distance D between the first edge 122a and the second edge 132a is greater than 200 μm, the spacing between the adjacent first contact portion 122 and the second contact portion 132 is large, resulting in an insufficient spacing of the contact portions 112 within the contact structure 102. Consequently, most of the area of ​​the connecting layer 103 (see Figure 1) will not be in contact with and connected to the contact structure 102 (see Figure 1). Thus, by designing the distance D between the first edge 122a and the second edge 132a to be 200 μm or less, a high spacing of the contact portions 112 within the contact structure 102 can be ensured, guaranteeing as much as possible that most of the area of ​​the connecting layer 103 can contact and connect to the contact structure 102, and ensuring a sufficient contact area between the connecting layer 103 and the contact structure 102.

[0082] Figure 8 shows an example where the orthographic projection shape of the contact portion 112 onto the cell substrate 100 is rectangular, and the distance D between the first edge 122a and the second edge 132a is shown. In actual applications, if the orthographic projection shape of the contact portion onto the cell substrate is other shapes, the distance between the first edge and the second edge may be 200 μm or less.

[0083] In some embodiments, referring to Figures 1 to 11, the thickness of the contact portion 112 in the thickness direction Z may be 1 μm to 10 μm, for example, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, or 9 μm.

[0084] In some embodiments, referring to Figures 1 to 11, the thickness of the connecting layer 103 may be 4 μm to 20 μm, for example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, or 19 μm.

[0085] The following describes in detail the materials of the contact portion 112 and the connecting layer 103.

[0086] In some embodiments, with reference to Figures 1 to 11, the material of the contact portion 112 may include silver particles, and the material of the connecting layer 103 may include copper particles or silver-plated copper particles.

[0087] Furthermore, the cost per unit mass of silver particles is higher than that of copper particles and higher than that of silver-plated copper particles. Also, the electrical connection performance between silver particles and the cell substrate 100 is higher than that between copper particles and the cell substrate 100 and higher than that between silver-plated copper particles and the cell substrate 100. Based on this, by designing the grid lines 101 so that only the contact structure material is silver particles, the silver particle content in the grid lines 101 can be significantly reduced while maximizing the electrical connection performance between the grid lines 101 and the cell substrate 100, thereby ensuring that the solar cell has a high photoelectric conversion efficiency. On the other hand, by designing the connecting layer 103, which has a larger demand for paste compared to the demand for paste in the contact structure 102, to contain copper particles or silver-plated copper particles, a sufficient amount of connecting layer 103 can be secured, not only allowing the connecting layer 103 to efficiently recover carriers from multiple contact parts 112 in the contact structure 102, but also reducing the manufacturing cost of forming the connecting layer 103.

[0088] In some cases, compared to simply using silver paste to form grid lines on the first or second surface, by designing the grid line 101 so that only the contact portion 112 contains silver particles, i.e., by using silver paste to form only the contact portion 112, the amount of silver paste required to form the contact portion 112 can be reduced to, for example, 3 mg to 15 mg. That is, compared to the case where the amount of silver paste used on one side is up to 40 mg when simply using silver paste to form grid lines on the first or second surface, the amount of silver paste used on one side can be reduced to 3 mg to 15 mg in the grid line 101 designed in one embodiment of this disclosure.

[0089] Furthermore, in the grid line 101 designed according to one embodiment of this disclosure, by designing the first contact portion 122 and the second contact portion 132 to be offset in the first direction X, it is possible not only to reduce the amount of silver paste required to form the contact portion 112, but also to further reduce the amount of silver paste required to form the contact portion 112 by reducing the thickness of the contact portion 112 in the thickness direction Z.

[0090] In some cases, referring to Figures 1 to 11, the material of the connecting layer 103 may contain copper particles, and the diameter of the copper particles may be 50 nm to 1500 nm, for example, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm, or 1400 nm.

[0091] In some other cases, referring to Figures 1 to 11, the material of the connecting layer 103 may include silver-plated copper particles, the diameter of which may be 50 nm to 1500 nm, for example, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm, or 1400 nm.

[0092] Note that the diameter of the silver-plated copper particles refers to the outer diameter of the silver-plated copper particles, that is, the diameter of the outer contour of the entire silver-plated copper particle.

[0093] In some examples, the proportion of silver in silver-plated copper particles is 15-50%, and may be, for example, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, or 49%.

[0094] The following describes the types of grid lines 101 in detail.

[0095] In some embodiments, with reference to Figure 12, which is another partial schematic plan view of a solar cell provided by one embodiment of the present disclosure, the grid line 101 is one of the ultrafine grid 104 and the main grid 105, and the other of the ultrafine grid 104 and the main grid 105 is a long structure extending in the first direction X. In Figure 12, an example is shown where the grid line 101 is the ultrafine grid 104 and the main grid 105 is a long structure extending in the first direction X, but in actual applications, the grid line may be the main grid and the ultrafine grid may be a long structure extending in the first direction.

[0096] Furthermore, whether it is the ultra-fine grid 104 or the main grid 105, by using the grid line 101 design described in each of the above embodiments, it is possible to improve the electrical connection performance between the grid line 101 and the cell substrate 100, and to reduce the manufacturing cost of the grid line 101. In addition, by designing the grid line 101 so that the contact portion 112 is offset, the difficulty of manufacturing the grid line 101 can be reduced.

[0097] Furthermore, in the cell substrate 100, the array density of the ultrafine grids 104 is greater than the array density of the main grids 105. Therefore, the total amount of material required to manufacture all the ultrafine grids 104 on one side is usually greater than the total amount of material required to manufacture all the main grids 105 on one side. As a result, compared to designing the grid lines 101 as described in each of the above embodiments for the main grids 105, designing the ultrafine grids 104 as described in each of the above embodiments reduces the total amount of material required to manufacture the grid lines 101, thereby reducing the manufacturing cost of the solar cell.

[0098] Furthermore, in some cases, the ultrafine grid 104 needs to be electrically connected to the cell substrate 100, while the main grid 105 does not need to be electrically connected to the cell substrate 100 and may be connected only by contact with the ultrafine grid 104. Carriers within the cell substrate 100 can first be collected by the ultrafine grid 104, and then by the main grid 105 which is connected in contact with the ultrafine grid 104. Thus, the material forming the main grid 105 does not need to achieve direct electrical connection between the main grid 105 and the cell substrate 100. For example, since the material forming the main grid 105 does not need to be embedded in the passivation layer in the cell substrate 100, a lower-cost material can be selected for the main grid 105 to achieve contact and connection between the main grid 105 and the ultrafine grid 104. As a result, by designing the ultrafine grid 104 to match the grid line 101 described in each of the above embodiments, the contact structure 102 can improve the performance of electrical contact between the ultrafine grid 104 and the cell substrate 100, and the connecting layer 103 can also reduce the manufacturing cost of the ultrafine grid 104. Moreover, in order to further reduce the manufacturing cost of the solar cell, a lower-cost material may be selected for the main grid 105.

[0099] Figures 1 to 12 all show examples in which a single first contact portion 122 and a single second contact portion 132 are offset in the first direction X in the second direction Y. In other words, in the examples shown in Figures 1 to 12, among the multiple contact portions 112 connected in contact with the same connecting layer 103, in the second direction Y, only one second contact portion 132 is interposed between two adjacent first contact portions 122, and only one first contact portion 122 is interposed between two adjacent second contact portions 132.

[0100] In actual applications, when designing adjacent first and second contact parts to be offset in the second direction, the number of second contact parts interposed between two adjacent first contact parts is not limited and may be, for example, two or three. Similarly, the number of first contact parts interposed between two adjacent second contact parts is not limited and may be, for example, two or three. In other words, in actual applications, there may be no second contact parts between two adjacent first contact parts in the second direction, or there may be no first contact parts between two adjacent second contact parts in the second direction. For example, one first contact part and three second contact parts may be considered as one set of arrangement groups, and multiple sets of arrangement groups may be repeated in the second direction.

[0101] In some other embodiments, refer together to Figures 1 and 13, where Figure 13 is a partially schematic plan view of the main grid in a solar cell provided in one embodiment of the present disclosure, where grid lines 101 are ultrafine grids, and the solar cell comprises a plurality of main grids 105 located on at least one of a first surface 110 (see Figure 3) and a second surface 120 (see Figure 3), spaced apart in a second direction Y, and including a connection structure 115 and an interconnection layer 125 electrically connected to a cell substrate 100, wherein the connection structure 115 includes a plurality of connection portions 135 sequentially arranged in a first direction X, and the interconnection layer 125 is in the first direction The interconnection layer 125 may further include a plurality of main grids 105 which are elongated structures extending in the direction X, and the interconnection layer 125 is connected in contact with a plurality of connection parts 135 of the connection structure 115, the connection parts 135 include first connection parts 145 and second connection parts 155 which are alternately arranged in the second direction Y, the interconnection layer 125 has third side parts 165 and fourth side parts 175 which are opposite each other in the first direction X, the first connection part 145 is connected in contact with at least the third side part 165 and the second connection part 155 is connected in contact with at least the fourth side part 175, and the material of the connection parts 135 and the material of the interconnection layer 125 are different.

[0102] Furthermore, the ultrafine grid includes a contact structure 102 that electrically connects to the cell substrate 100, and the main grid 105 also includes a connection structure 115 that electrically connects to the cell substrate 100. In other words, not only is a portion of the ultrafine grid directly electrically connected to the cell substrate 100, but a portion of the main grid 105 is also directly electrically connected to the cell substrate 100. As a result, carriers within the cell substrate 100 can be collected not only by first passing through the ultrafine grid and then through the main grid 105, but also by being directly collected by the main grid 105 via the connection structure 115. Therefore, the transport distance over which some carriers within the cell substrate 100 are transported to the main grid 105 can be shortened, reducing carrier transport losses, thereby improving the carrier collection efficiency by the main grid 105 and improving the photoelectric conversion efficiency of the solar cell.

[0103] Furthermore, the connection structure 115 of the main grid 105 is similar to the contact structure 102 of the ultra-fine grid, the connection portion 135 included in the connection structure 115 is similar to the contact portion 112 of the contact structure 102, the first connection portion 145 is similar to the first contact portion 122, the second connection portion 155 is similar to the second contact portion 132, the interconnection layer 125 is similar to the connection layer 103, the third side portion 165 is similar to the first side portion 113, and the fourth side portion is similar to the second side portion 123. The differences are that the specific size of the connection portion 135 and the specific size of the contact portion 112 are different, and the specific size of the interconnection layer 125 and the specific size of the connection layer 103 are different. Here, a detailed explanation of the connection structure 115 and the interconnection layer 125 included in the main grid 105 is omitted. Furthermore, Figure 13 shows only one case of contact and connection between the connection structure 115 and the interconnection layer 125 of the main grid 105. Other cases of contact and connection between the connection structure 115 and the interconnection layer 125 can be seen by referring to the case of contact and connection between the contact structure and the interconnection layer described above.

[0104] The following provides a detailed explanation of the different types of solar cells.

[0105] In some embodiments, the solar cell is a solar cell having grid lines on both sides, and may be one or a combination of, for example, a PERC cell, a TOPCON cell, a HIT / HJT cell (Heterojunction Technology, heterojunction cell), or a thin-film solar cell. Here, the thin-film solar cell includes, but is not limited to, a perovskite thin-film solar cell, a copper-indium-selenium thin-film solar cell, a gallium-arsenide thin-film solar cell, or a cadmium sulfide thin-film solar cell.

[0106] Based on this, referring to Figure 3, the first surface 110 of the cell substrate 100 may be the front surface, and the first surface 110 has a plurality of front ultrafine grids (not shown) arranged at intervals in the first direction X and a plurality of front main grids (not shown) arranged at intervals in the second direction Y. The second surface 120 of the cell substrate 100 may be the back surface, and the second surface 120 has a plurality of back ultrafine grids arranged at intervals in the first direction X and a plurality of back main grids (not shown) arranged at intervals in the second direction Y.

[0107] Furthermore, the solar cell may be a single-sided cell, meaning that the first surface 110 can be a light-receiving surface that receives incident light rays, and the second surface 120 can be a non-light-receiving surface. Alternatively, the solar cell may be a double-sided cell, in which case both the first surface 110 and the second surface 120 can be light-receiving surfaces that receive incident light rays. In addition, the non-light-receiving surface described in one embodiment of this disclosure may receive incident light rays, but is defined as a non-light-receiving surface because its light-receiving intensity for incident light rays is weaker than that for incident light rays on the light-receiving surface.

[0108] In some cases, referring to Figure 3, the back ultrafine grid may be the grid lines 101 described in each of the above embodiments, and the back main grid, front ultrafine grid, and front main grid may all be single-layer elongated structures. This reduces the manufacturing cost of the solar cell by using the grid lines 101 located on the second surface 120, and prevents the front main grid and back main grid located on the first surface from excessively shielding the cell substrate 100, thereby ensuring that the solar cell has a sufficient light-receiving surface.

[0109] In some other cases, the back ultrafine grid and the front ultrafine grid may both be the grid lines 101 described in each of the above embodiments (see Figures 1 to 11), the back main grid and the front main grid may both be a single-layer elongated structure, or the back main grid and the front main grid may both be the main grid 105 described above (see Figure 13).

[0110] In some further cases, the back ultrafine grid may be the grid lines 101 described in each of the above embodiments (see Figures 1 to 11), and the back main grid may be the main grid 105 described above (see Figure 13). Both the front ultrafine grid and the front main grid may be single-layer elongated structures.

[0111] In some further cases, the front ultrafine grid may be the grid lines 101 described in each of the above embodiments (see Figures 1 to 11), and the front main grid may be the main grid 105 described above (see Figure 13). Both the back ultrafine grid and the back main grid may be single-layer elongated structures.

[0112] In another embodiment, the solar cell is a back contact cell, i.e., a BC cell, which includes, but is not limited to, IBC cells (Interdigitated Back Contact), HBC cells (Heterojunction Back Contact), TBC cells ((TOPCon Back Contact) solar cells, or Back contact-based tunnel oxide passivating contact), or HPBC cells (Hybrid Passivated Back Contact). Thus, referring to Figure 3, the first surface 110 or the second surface 120 may be considered the back surface of the finally formed solar cell.

[0113] Based on this, the back of the solar cell includes a back ultra-fine grid and a back main grid.

[0114] In some cases, the ultra-fine back grid located on the first or second surface may be the grid lines 101 described in each of the above embodiments (see Figures 1 to 11), and the main back grid may be a single-layer elongated structure.

[0115] In some other cases, the back ultrafine grid located on the first or second surface may be the grid lines 101 described in each of the above embodiments (see Figures 1 to 11), and the back main grid located on the first or second surface may be the main grid 105 described above (see Figure 13).

[0116] In short, the first contact portion 122 and the second contact portion 132 adjacent in the second direction Y of the contact structure 102 may be offset in the first direction X. In this way, compared to manufacturing a contact structure that is a long structure similar to the connecting layer 103, assuming that the size of the connecting layer 103 is the same, the offset arrangement of the first contact portion 122 and the second contact portion 132 ensures that the contact structure 102 and the connecting layer 103 have a sufficient contact area, while reducing the amount of material required for the contact structure 102. This improves the performance of the electrical connection between the grid line 101 and the cell substrate 100 and reduces the manufacturing cost of the grid line 101. However, in the first direction X, The first contact portion 122 has a third edge that is separated from the second contact portion 132, and the second contact portion 132 has a fourth edge that is separated from the first contact portion 122. The offset arrangement of the first contact portion 122 and the second contact portion 132 allows for a wider gap between the third edge and the fourth edge in the first direction X. Therefore, compared to manufacturing a contact structure that is elongated like the connecting layer 103, assuming the connecting layer 103 is the same size, the requirements for alignment accuracy between the connecting layer 103 and the contact structure 102 can be reduced. In other words, the offset arrangement of the first contact portion 122 and the second contact portion 132 allows for a larger offset error in the first direction X between the connecting layer 103 and the contact structure 102, and within this offset error, the contact area between the connecting layer 103 and the contact structure 102 does not change. This further ensures high contact performance between the contact structure 102 and the connecting layer 103, and reduces the manufacturing difficulty of the connecting layer 103 and the grid lines 101.

[0117] Another embodiment of this disclosure further provides a method for manufacturing solar cells for producing the solar cells provided in the above embodiment. The method for manufacturing solar cells provided in another embodiment of this disclosure will be described in detail below, with the help of the drawings. Details of parts that are the same as or corresponding to the above embodiment will be omitted here.

[0118] Referring to Figures 1 to 11, the method for manufacturing a solar cell comprises the steps of: providing a cell substrate 100 having a first surface 110 and a second surface 120 facing opposite directions in the thickness direction Z; and forming a plurality of grid lines 101 on the first surface 110 and / or the second surface 120, spaced apart in a first direction X, wherein the grid lines 101 include a contact structure 102 and a connecting layer 103 electrically connected to the cell substrate 100, the contact structure 102 includes a plurality of contact portions 112 sequentially arranged in a second direction Y intersecting the first direction X, and the connecting layer 103 is a long structure extending in the second direction Y. The connecting layer 103 is connected to a plurality of contact portions 112 of the contact structure 102 by contact, the contact portions 112 include first contact portions 122 and second contact portions 132 arranged alternately in a second direction Y, the connecting layer 103 has first side portions 113 and second side portions 123 facing each other in a first direction X, the first contact portion 122 is connected to at least the first side portion 113 by contact, and the second contact portion 132 is connected to at least the second side portion 123 by contact, and the material of the contact portions 112 and the material of the connecting layer 103 are different.

[0119] In some cases, referring to Figures 1, 4, 5, or 6, by designing the first contact portion 122 to be connected in contact with at least the first side portion 113 and the second contact portion 132 to be connected in contact with at least the second side portion 123, adjacent first contact portions 122 and second contact portions 132 in the second direction Y can be offset in the first direction X. The first contact portion 122 is connected in contact with at least the first side portion 113 and the second contact portion 132 is connected in contact with the second side portion 123, or the second contact portion 132 is connected in contact with at least the second side portion 123 and the first contact portion 122 is connected in contact with the first side portion 113.

[0120] In some other cases, referring to Figure 7, it is also possible to design the first contact portion 122 to be connected in contact with at least the first side portion 113 and the second contact portion 132 to be connected in contact with at least the second side portion 123, so that adjacent first contact portions 122 and second contact portions 132 in the second direction Y are spaced apart in the second direction Y, so that the first contact portion 122 is connected in contact with either the first side portion 113 or the second side portion 123, and the second contact portion 132 is connected in contact with either the first side portion 113 or the second side portion 123.

[0121] Furthermore, by dividing the contact portion 112 of the contact structure 102 into a first contact portion 122 that is connected by contacting at least the first side portion 113 and a second contact portion 132 that is connected by contacting at least the second side portion 123, the positional relationship between both the first contact portion 122 and the second contact portion 132 and the connecting layer 103 can be adjusted, thereby ensuring that the contact structure 102 and the connecting layer 103 have a sufficient contact area while reducing the amount of material required for the contact structure 102. This improves the performance of the electrical connection between the grid wire 101 and the cell substrate 100 and reduces the manufacturing cost of the grid wire 101.

[0122] The manufacturing procedure for grid wire 101 will be described in detail below.

[0123] In some embodiments, referring together to Figures 2 and 3, the grid lines 101 may be an extremely fine grid, and the second surface 120 has a first printing area (not shown in the figure) and a second printing area (not shown in the figure) that at least partially overlaps the first printing area. The first printing area corresponds to a contact structure 102 that is formed later, and the second printing area corresponds to a connecting layer 103 that is formed later. In other words, the first printing area is substantially an orthographic projection of the contact structure 102 that is formed later onto the cell substrate 100, and the second printing area is substantially an orthographic projection of the connecting layer 103 that is formed later onto the cell substrate 100.

[0124] Continuing with reference to Figures 2 and 3, the step of forming the grid lines 101 includes the steps of printing a first paste onto a first printing area using a first screen printing process, performing a sintering process on the first paste to form a contact structure 102 corresponding to the first printing area, printing a second paste onto a second surface 120 using a second screen printing process, and performing a curing process on the second paste to form a connecting layer 103 corresponding to the second printing area, wherein the first paste is a burn-through type paste, the second paste is a non-burn-through type paste, and the process temperature of the sintering process is greater than the process temperature of the curing process.

[0125] Since the first paste is a burn-through type paste and the second paste is a non-burn-through type paste, the final contact structure 102 is electrically connected to the cell substrate 100, for example, embedded in the passivation layer of the cell substrate 100. However, the connection layer 103 is located only on the surface of the cell substrate 100, that is, it is not embedded in the passivation layer of the cell substrate 100, nor is it directly electrically connected to the cell substrate 100.

[0126] In some cases, the first paste may be silver paste, and the second paste may be copper paste or silver-plated copper paste. In practical applications, the alternating design of the first contact portion 122 and the second contact portion 132 in the contact structure 102 can reduce the unit consumption of the first paste on one side to 3 mg to 15 mg, for example, 4 mg, 5 mg, 6 mg, 7 mg, 8 mg, 9 mg, 10 mg, 11 mg, 12 mg, 13 mg, or 14 mg.

[0127] In some cases, the solid content in the silver paste may be 75% to 92%, for example, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, or 91%.

[0128] Furthermore, the solids in the silver paste include at least glass frit in addition to silver particles, and the solid content in the silver paste refers to the total content of all solids, including silver particles, in the silver paste.

[0129] In some cases, in the process of printing and forming all grid lines using silver paste, the solid content in the silver paste used is usually high, for example, greater than 90%. This allows for a lower solid content in the silver paste used in the solar cell manufacturing method provided in another embodiment of this disclosure compared to the process of printing and forming the entire grid line using silver paste. This results in a lower concentration of silver paste forming the contact structure 102, in other words, a lower viscosity of silver paste forming the contact structure 102. Thus, when the silver paste is printed onto the first printing area of ​​the cell substrate 100, the silver paste can spread to some extent on the cell substrate 100, thereby increasing the contact area between the contact structure 102 formed by the silver paste and the cell substrate 100.

[0130] The second surface 120 described above may be considered the back surface of the solar cell, and a grid line 101 including a contact structure 102 and a connecting layer 103 can be formed on the second surface 120 by combining the first screen printing process and the second screen printing process. Furthermore, although the above shows an example of forming a grid line 101 on the second surface 120, in actual applications, the grid line may also be formed on the first surface by applying the first screen printing process and the second screen printing process to the first surface, and a detailed explanation is omitted here. Furthermore, although the above shows an example in which the grid line 101 formed on the second surface 120 is an ultra-fine grid, in actual applications, the grid line formed by combining the first screen printing process and the second screen printing process may also be a main grid, and the grid line as a main grid may be formed on the first surface or the second surface, and a detailed explanation is omitted here.

[0131] Referring to Figure 13, if the main grid 105 is designed to include a connection structure 115 and an interconnection layer 125 that are electrically connected to the cell substrate 100 (see Figure 2), the formation process of the connection structure 115 is similar to the formation process of the contact structure 102 (see Figures 1 to 11), and the formation process of the interconnection layer 125 is similar to the formation process of the connection layer 103 (see Figures 1 to 11). A detailed explanation is omitted here.

[0132] The following describes in detail the manufacturing procedure for the main grid 105, excluding the grid line 101 located on the second surface 120.

[0133] In some cases, referring to Figure 2, the second surface 120 further has a third printing area (not shown), and in the step of performing the first screen printing process, the first paste is further printed on the third printing area, and in the step of performing the sintering process, a main grid corresponding to the third printing area is further formed. The third printing area corresponds to the main grid that is formed later. In other words, the third printing area is substantially an orthographic projection of the main grid that is formed later onto the cell substrate 100.

[0134] Furthermore, the manufacturing of the contact structure 102 among the grid lines 101 may be carried out in the same steps as the manufacturing of the main grid, thereby eliminating one printing process and further reducing the manufacturing cost of the solar cell.

[0135] In some other cases, referring to Figure 2, the second surface 120 further has a third printing area (not shown), and in the step of performing a second screen printing process, the second paste is further printed onto the third printing area, and in the step of curing, a main grid 105 corresponding to the third printing area is further formed (see Figure 12). The third printing area corresponds to the main grid 105 that is formed later. In other words, the third printing area is substantially an orthographic projection of the main grid 105 that is formed later onto the cell substrate 100.

[0136] Furthermore, the manufacturing of the connecting layer 103 of the grid lines 101 may be carried out in the same step as the manufacturing of the main grid 105, which also reduces one printing process and further lowers the manufacturing cost of the solar cell.

[0137] In some further cases, a first screen printing process is combined with a sintering process to form only the contact structures of the grid lines, a second screen printing process is combined with a hardening process to form only the connecting layers of the grid lines, and then the main grid located on the second surface is formed by other processes.

[0138] In the various cases described above, referring in conjunction with Figures 3 and 12, the ultrafine grid 104 formed on the second surface 120 may be a back ultrafine grid, the main grid 105 formed on the second surface 120 is a back main grid, and the first surface 110 has a fourth printing area (not shown) extending in the first direction X and a fifth printing area (not shown) extending in the second direction Y. The fourth printing area corresponds to the front ultrafine grid that is formed later, and the fifth printing area corresponds to the front main grid that is formed later. In other words, the fourth printing area is substantially an orthographic projection of the front ultrafine grid that is formed later onto the cell substrate 100, and the fifth printing area is substantially an orthographic projection of the front main grid that is formed later onto the cell substrate 100.

[0139] Prior to the sintering process, the method for manufacturing a solar cell may further include the steps of: printing a third paste onto a fourth printing area using a third screen printing process; performing a sintering process, further performing the sintering process on the third paste to form a front ultrafine grid corresponding to the fourth printing area; printing a fourth paste onto a fifth printing area using a fourth screen printing process; and performing the sintering process, further performing the sintering process on the fourth paste to form a front main grid corresponding to the fifth printing area.

[0140] In some cases, the third paste and the fourth paste may be the same, that is, the material for the front ultra-fine grid and the material for the front main grid may be the same.

[0141] The order of the third screen printing process and the fourth screen printing process may be reversed.

[0142] As can be seen from the above explanation, when the back ultrafine grid is defined as grid line 101, the printing procedure for the solar cell includes at least the following cases. In some cases, the four components—the back main grid, the contact structure 102 of the grid line 101, the front main grid, and the front ultrafine grid—may be formed by four separate printing processes, then sintered together, and finally the printing and curing process for the connecting layer 103 of the grid line 101. In some other cases, the back main grid and the contact structure 102 of the grid line 101 may be formed by the same printing process, the front main grid and the front ultrafine grid may be formed by two separate printing processes, then sintered together, and finally the printing and curing process for the connecting layer 103 of the grid line 101. In some other cases, the contact structure 102, the front main grid, and the front ultra-fine grid of the grid lines 101 may be formed by three separate printing processes, then sintered together, the back main grid and the connecting layer 103 of the grid lines 101 may be formed by the same printing process, and finally a hardening process may be performed.

[0143] Another embodiment of the present disclosure further provides a stack cell, which includes a solar cell provided in the above embodiment or a solar cell manufactured by a method for manufacturing a solar cell provided in the above embodiment. Below, with the help of the drawings, the stack cell provided in another embodiment of the present disclosure will be described in detail. Details of parts that are the same as or corresponding to the above embodiment will be omitted here.

[0144] Referring to Figure 14, which is a partial schematic cross-sectional view of a stacked solar cell provided in another embodiment of the present disclosure, the stacked solar cell (Tandem solar cell) includes a bottom cell 106 which is a solar cell provided in the above embodiment or manufactured by the method for manufacturing a solar cell provided in the above embodiment, and a top cell 107 located on one side of the bottom cell 106.

[0145] In some embodiments, the top cell 107 may be one of the following: a perovskite solar cell, a donor-acceptor type cell, a cadmium telluride (CdTe) solar cell, a copper-indium gallium selenide (CIGS) solar cell, or a gallium arsenide (GaAs) solar cell.

[0146] In some embodiments, the top cell 107 may include a laminated first transport layer, a perovskite substrate, a second transport layer, a transparent conductive layer, and an anti-reflective layer. The first transport layer faces the bottom cell 106.

[0147] In some examples, the first transport layer may be either an electron transport layer or a hole transport layer, and the second transport layer may be the other of the electron transport layer or a hole transport layer.

[0148] In some embodiments, the bandgap width of the top cell 107 is larger than that of the bottom cell 106. Therefore, by stacking the top cell 107 above the bottom cell 106, the stacked cells can have a wider spectral response range, maximizing the utilization of solar energy and improving the efficiency of the solar cell.

[0149] In some embodiments, the back-contact stack cell may further include an intermediate connecting layer (not shown) connected between the bottom cell 106 and the top cell 107.

[0150] In some cases, the intermediate connecting layer is typically a tunnel junction or a very thin metal or transparent electrode composite layer. Preferably, the intermediate connecting layer may be a transparent conductive oxide. Transparent conductive oxides have excellent photoelectric properties and high photon transmittance and conductivity, so that the top cell 107 and the bottom cell 106 can maintain good ohmic contact.

[0151] In some other cases, the back nanogrid, back main grid, front nanogrid, and front main grid in the solar cell as the bottom cell 106 may also be electrically connected to the top cell 107 as an intermediate connecting layer.

[0152] Further embodiments of this disclosure further provide a photovoltaic assembly comprising a plurality of solar cells provided in the above embodiments, or a plurality of solar cells manufactured by the method for manufacturing solar cells provided in the above embodiments, or a plurality of stacked cells provided in the above embodiments, wherein the photovoltaic assembly converts absorbed light energy into electrical energy. For parts that are the same as or corresponding to the above embodiments, refer to the corresponding descriptions of the above embodiments; detailed descriptions are omitted below.

[0153] Referring together to Figures 15, 16, and Figures 1 to 13, the photovoltaic assembly includes a cell string formed by connecting a plurality of solar cells 40 provided in the above embodiment, or a plurality of solar cells 40 manufactured by the solar cell manufacturing method provided in the above embodiment, or a plurality of stacked cells provided in the above embodiment; a sealing film 41 covering the surface of the cell string; and a cover plate 42 covering the surface of the sealing film 41 away from the cell string.

[0154] Here, Figure 15 is a partial schematic perspective view of a cell string in a photovoltaic assembly provided in yet another embodiment of the present disclosure, and Figure 16 is a partial schematic cross-sectional view of a photovoltaic assembly provided in yet another embodiment of the present disclosure.

[0155] In some embodiments, the solar cell 40 is electrically connected in the form of full cells or cut cells to form a plurality of cell strings, and the plurality of cell strings are electrically connected in series and / or parallel. The solar cell 40 may be a full cell or a cut cell, where a cut cell means a cell formed by cutting a complete full cell.

[0156] In some embodiments, with reference to Figures 15 and 16, multiple solar cells 40 can be electrically connected to each other via a conductive strip 43. Figures 15 and 16 show only one positional relationship between the solar cells 40. That is, the grid lines of the solar cells 40 having the same polarity are arranged in the same direction. In other words, all grid lines with positive polarity of each solar cell 40 are arranged on the same side, so that the conductive strip connects the different sides of two adjacent solar cells 40. In other embodiments, the electrodes of the solar cells may be arranged on the same side with electrodes of different polarities. That is, the electrodes of multiple adjacent solar cells are arranged in the order of first polarity, second polarity, first polarity, so that the conductive strip connects two adjacent solar cells on the same side.

[0157] In some embodiments, the sealing film 41 includes a first sealing layer covering either the front or back of the solar cell 40, and a second sealing layer covering the other of the front or back of the solar cell 40. Specifically, at least one of the first and second sealing layers may be an organic sealing film such as polyvinyl butyral (PVB) film, ethylene vinyl acetate copolymer (EVA) film, polyolefin elastomer (POE) film, or polyethylene terephthalate (PET) film, or at least one of the first or second sealing layer may further be an adhesive film such as an EP adhesive film, an EPE adhesive film, or a PVP adhesive film. Here, EP adhesive film refers to a co-extruded adhesive film composed of laminated EVA adhesive film and POE adhesive film, EPE adhesive film refers to a co-extruded adhesive film formed by sequentially laminated EVA adhesive film + POE adhesive film + EVA adhesive film, and PVP adhesive film refers to a co-extruded adhesive film formed by laminated POE adhesive film + EVA adhesive film + POE adhesive film. As a method for manufacturing co-extruded adhesive films, one or more types of raw materials can be sequentially extruded onto other already manufactured adhesive films during the processing of the adhesive film, or different types of already manufactured adhesive films can be bonded to each other.

[0158] In some cases, there is a boundary between the first and second sealing layers before lamination, but after the lamination process, the photovoltaic assembly is formed and the concepts of the first and second sealing layers no longer exist; that is, the first and second sealing layers already form a single sealing film 41.

[0159] In some embodiments, the cover plate 42 may be a light-transmitting cover plate such as a glass cover plate or a plastic cover plate. Specifically, by making the surface of the cover plate 42 facing the sealing film 41 an uneven surface or a textured surface including a plurality of protruding structures, the utilization rate of incident light rays can be increased. The cover plate 42 includes a first cover plate and a second cover plate, the first cover plate facing the first sealing layer and the second cover plate facing the second sealing layer.

[0160] Those skilled in the art will understand that the above embodiments are specific examples for carrying out the present disclosure, and that in actual application, various formal and detailed modifications can be made without departing from the spirit and scope of the embodiments of the present disclosure. Those skilled in the art can also make any changes and modifications without departing from the gist and scope of the embodiments of the present disclosure, so the scope of protection of the embodiments of the present disclosure shall be limited to the scope defined by the claims. [Explanation of Symbols]

[0161] 100-cell substrate 110 Page 1 120 Side 2 101 grid lines 102 Contact structure 112 Contact section 122 First Contact Section 122a 1st edge 1221 Part 1 1222 Part 2 132 Second Contact Section 132a Second edge 103 Connectivity Layer 113 First side 123 Second side 104 ultra-fine grid 105 Main Grid 115 Connection Structure 125 Interconnection Layer 135 Connection part 145 First connection section 155 Second connection section 165 Third side 175 Fourth side 106 bottom cells 107 Top Cell 40 Solar Cells 41 Sealing film 42 Cover Plate 43 Conductive strip

Claims

1. A cell substrate having a first surface and a second surface facing opposite directions in the thickness direction, A plurality of grid lines as an ultrafine grid located on the first surface and / or the second surface and arranged at intervals in the first direction, comprising a contact structure and a connecting layer electrically connected to the cell substrate, wherein the contact structure comprises a plurality of contact portions sequentially arranged in a second direction intersecting the first direction, and the connecting layer has an elongated structure extending in the second direction, A main grid is a long, elongated structure connected to a plurality of grid lines and extending along the first direction, The connecting layer is connected by contacting a plurality of the contact portions of the contact structure. The contact portion and the connecting layer are made of different materials, and their orthographic projections onto the cell substrate partially overlap. The contact portion includes a first contact portion and a second contact portion arranged alternately in the second direction. The connecting layer has a first side portion and a second side portion facing opposite directions in the first direction, The first contact portion is connected in contact with at least the first side portion and the second contact portion is connected in contact with the second side portion, or the second contact portion is connected in contact with at least the second side portion and the first contact portion is connected in contact with the first side portion. In the first direction, the width of the first exposed portion of the first contact portion exposed from the connecting layer and the width of the second exposed portion of the second contact portion exposed from the connecting layer are both smaller than the width of the connecting layer. Solar cell.

2. In the same grid line, the first contact portion and the second contact portion are not facing each other in the second direction. The solar cell according to claim 1.

3. Within the same grid line, a portion of the first contact portion and a portion of the second contact portion face each other in the second direction. The solar cell according to claim 1.

4. In the second direction, the portion of the first contact portion facing the second contact portion is the first portion, and the width of the portion of the first contact portion other than the first portion in the first direction is 25 μm or less. The solar cell according to claim 3.

5. In the thickness direction, the orthographic projection of the contact portion onto the cell substrate is circular, elliptical, triangular, rectangular, trapezoidal, or N-sided, where N is a positive integer greater than 4. The solar cell according to claim 1.

6. In the thickness direction, the orthographic projection shape of the contact portion onto the cell substrate is circular or elliptical, and in the second direction, adjacent first contact portions and second contact portions are in contact. The solar cell according to claim 1.

7. In the thickness direction, the orthographic projection area of ​​the contact portion onto the cell substrate is between 100 μm² and 5000 μm². The solar cell according to claim 1.

8. The width of the connecting layer in the first direction is 10 μm to 70 μm. The solar cell according to claim 1.

9. In the second direction, of the adjacent first contact portion and the second contact portion, the edge of the first contact portion closest to the second contact portion is the first edge, and the edge of the second contact portion closest to the first contact portion is the second edge. The distance between the first edge and the second edge is 200 μm or less. The solar cell according to claim 1.

10. The thickness of the contact portion in the thickness direction is 1 μm to 10 μm, and / or the thickness of the connecting layer is 4 μm to 20 μm. The solar cell according to claim 1.

11. The main grid is a plurality of main grids located on at least one of the first surface and the second surface and arranged at intervals in the second direction, comprising a connection structure and an interconnection layer electrically connected to the cell substrate, wherein the connection structure comprises a plurality of connection portions sequentially arranged in the first direction, and the interconnection layer is a long structure extending in the first direction, The interconnection layer is connected by contacting a plurality of the connection parts of the connection structure. The connecting portion includes a first connecting portion and a second connecting portion that are arranged alternately in the second direction. The interconnection layer has a third side portion and a fourth side portion facing opposite directions in the first direction, The first connecting portion is connected in contact with at least the third side portion, and the second connecting portion is connected in contact with at least the fourth side portion. The material of the connecting portion and the material of the interconnecting layer are different. The solar cell according to claim 1.

12. The material of the contact portion contains silver particles, The material of the connecting layer includes copper particles or silver-plated copper particles. The solar cell according to claim 1.

13. The diameter of the copper particles is 50 nm to 1500 nm, or the diameter of the silver-plated copper particles is 1 μm to 10 μm, or the proportion of silver in the silver-plated copper particles is 15% to 50%. The solar cell according to claim 12.

14. The step of providing a cell substrate having a first surface and a second surface facing opposite directions in the thickness direction, The first surface and / or the second surface are formed with grid lines as a plurality of ultrafine grids arranged at intervals in a first direction, the grid lines include a contact structure and a connecting layer electrically connected to the cell substrate, the contact structure includes a plurality of contact portions sequentially arranged in a second direction intersecting the first direction, and the connecting layer is a long structure extending in the second direction. The step of forming a main grid which is a long structure connected to a plurality of grid lines and extending along the first direction, The connecting layer is connected by contacting a plurality of the contact portions of the contact structure, and the contact portions and the connecting layer are made of different materials, and the orthographic projections of both onto the cell substrate partially overlap. The contact portion includes a first contact portion and a second contact portion arranged alternately in the second direction. The connecting layer has a first side portion and a second side portion facing opposite directions in the first direction, The first contact portion is connected in contact with at least the first side portion and the second contact portion is connected in contact with the second side portion, or the second contact portion is connected in contact with at least the second side portion and the first contact portion is connected in contact with the first side portion. In the first direction, the width of the first exposed portion of the first contact portion exposed from the connecting layer and the width of the second exposed portion of the second contact portion exposed from the connecting layer are both smaller than the width of the connecting layer. A method for manufacturing solar cells.

15. The second surface has a first printing area and a second printing area that at least partially overlaps the first printing area, The step of forming the grid lines is: A step of printing a first paste onto the first printing area using a first screen printing process, The steps include: performing a sintering process on the first paste to form the contact structure corresponding to the first printing area; The steps include printing a second paste onto the second surface using a second screen printing process, The step includes curing the second paste to form the connecting layer corresponding to the second printing area, The first paste is a burn-through type paste, The second paste is a non-burn-through type paste. The process temperature of the sintering process is greater than the process temperature of the hardening process. A method for manufacturing a solar cell according to claim 14.

16. The first paste is a silver paste, The second paste is a copper paste or a silver-plated copper paste. A method for manufacturing a solar cell according to claim 15.

17. The solid content in the aforementioned silver paste is 75% to 92%. A method for manufacturing a solar cell according to claim 16.

18. The aforementioned second surface further includes a third printing area, In the step of performing the first screen printing process, the first paste is further printed on the third printing area, and in the step of performing the sintering process, the main grid corresponding to the third printing area is formed, or In the step of performing the second screen printing process, the second paste is further printed onto the third printing area, and in the step of performing the curing process, the main grid corresponding to the third printing area is formed. A method for manufacturing a solar cell according to claim 15.

19. The ultrafine grid formed on the second surface is a back ultrafine grid, The main grid formed on the second surface is the back main grid, The first surface has a fourth printing area extending in the first direction and a fifth printing area extending in the second direction, Before performing the sintering process, the method for manufacturing the solar cell is as follows: A step of printing the third paste onto the fourth printing area using a third screen printing process, In the step of performing the sintering process, the third paste is subjected to the sintering process to form a front ultrafine grid corresponding to the fourth printing area, The steps include printing the fourth paste onto the fifth printing area using a fourth screen printing process, The step of performing the sintering process further includes the step of performing the sintering process on the fourth paste to form a front main grid corresponding to the fifth printing area, A method for manufacturing a solar cell according to claim 18.

20. A bottom cell which is a solar cell according to claim 1, The top cell located on one side of the bottom cell, A stack cell containing this cell.

21. A cell string comprising a plurality of solar cells as described in any one of claims 1 to 13 connected together, or a plurality of stacked cells as described in claim 20 connected together, A sealing film covering the surface of the cell string, A cover plate that covers the surface of the sealing film away from the cell string, A solar power assembly including a solar power generation system.

Images