Solar cell, and photovoltaic module and manufacturing method therefor

Abstract

The present disclosure provides a solar cell, and a photovoltaic module and a manufacturing method therefor. The solar cell comprises a cell substrate (100), back electrodes (110) and a conductive enhancement layer (120); a plurality of back electrodes (110) are provided, and the plurality of back electrodes (110) are arranged on the backlight surface of the cell substrate (100); and the conductive enhancement layer (120) is arranged on the side of the back electrodes (110) distant from the backlight surface, the conductive enhancement layer (120) is connected to the plurality of back electrodes (110), and the conductive enhancement layer (120) covers at least part of the backlight surface of the cell substrate (100).

Description

Solar cell, photovoltaic module and preparation method thereof

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 24, 2023, with application number 202311601895.X and public name “Solar cells, photovoltaic modules and their preparation methods”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present disclosure relates to the field of photovoltaic technology, and in particular to a solar cell, a photovoltaic module and a preparation method thereof. Background Art

[0003] A solar cell is a semiconductor device that converts light energy into electrical energy. The core component of a solar cell typically includes a PN junction. In addition, to conduct photogenerated carriers to the external circuit, it typically includes transparent conductive layers and gate electrodes on the front and back sides. The gate electrodes are designed to expose as much of the solar cell surface as possible, thereby maximizing the surface area available for receiving sunlight. However, in some practical applications, the actual power generation capacity of solar cells still needs to be further improved.

[0004] Summary of the Invention

[0005] In a first aspect, according to some embodiments of the present disclosure, a solar cell is provided, comprising a cell substrate, a back electrode, and a conductive enhancement layer, wherein the cell substrate has a light-facing surface and a backlight surface that are relatively arranged, there are multiple back electrodes, and the multiple back electrodes are arranged on the backlight surface of the cell substrate, the conductive enhancement layer is arranged on the side of the back electrode away from the backlight surface, the conductive enhancement layer is connected to the multiple back electrodes, and the conductive enhancement layer covers at least part of the backlight surface of the cell substrate.

[0006] In some embodiments of the present disclosure, the material of the conductive reinforcement layer includes metal.

[0007] In some embodiments of the present disclosure, the conductive enhancement layer includes a metal foil, and the metal foil is welded to the back electrode.

[0008] In some embodiments of the present disclosure, the conductive enhancement layer includes metal paint, and the metal paint is coated on the back electrode.

[0009] In some embodiments of the present disclosure, the conductive enhancement layer includes a conductive adhesive, and the conductive adhesive is adhered to the back electrode.

[0010] In some embodiments of the present disclosure, the thickness of the conductive reinforcement layer is 5 μm to 100 μm.

[0011] In some embodiments of the present disclosure, the thermal conductivity of the conductive reinforcement layer is higher than the thermal conductivity of the battery substrate.

[0012] In some embodiments of the present disclosure, the conductive enhancement layer covers the entire backlight surface of the battery substrate.

[0013] In some embodiments of the present disclosure, the conductive enhancement layer covers a portion of the backlight surface of the battery substrate.

[0014] In some embodiments of the present disclosure, the conductive enhancement layer includes a plurality of conductive portions arranged at intervals, the conductive portions are in the shape of long strips, and an extension direction of the conductive portions intersects with an extension direction of the back electrode.

[0015] In some embodiments of the present disclosure, the conductive enhancement layer includes a plurality of conductive parts arranged at intervals, the number of the conductive parts corresponds to the number of the back electrodes, and each of the conductive parts covers the corresponding back electrode.

[0016] In some embodiments of the present disclosure, the area ratio of the backlight surface covered by the conductive enhancement layer to the entire backlight surface is greater than 50%.

[0017] In a second aspect, according to some embodiments of the present disclosure, a photovoltaic assembly is provided, comprising a plurality of solar cells as described in any of the above embodiments, wherein two adjacent solar cells are electrically connected.

[0018] In some embodiments of the present disclosure, the photovoltaic module further includes a connector, and two adjacent solar cells are electrically connected via the connector. The connector includes an overlapping portion arranged on the backlight surface, and the conductive reinforcement layer also covers at least a portion of the overlapping portion.

[0019] In some embodiments of the present disclosure, the photovoltaic module further includes a front contact pad arranged on the light-facing surface of the cell substrate and a back contact pad arranged on the backlight surface of the cell substrate. In two adjacent solar cells, the front contact pad in one of the solar cells is aligned with the back contact pad in the other solar cell.

[0020] In a third aspect, according to some embodiments of the present disclosure, a method for preparing a photovoltaic module is provided, comprising the following steps:

[0021] Providing a plurality of battery substrates, and preparing a plurality of back electrodes on the backlight surface of each of the battery substrates;

[0022] connecting a plurality of the battery substrates; and,

[0023] A conductive enhancement layer is prepared on the side of the back electrode away from the battery substrate.

[0024] In some embodiments of the present disclosure, in the step of connecting the two adjacent battery substrates, the two adjacent battery substrates are connected by a connector, wherein the connector includes a lap portion provided on the backlight surface of the battery substrate;

[0025] In the step of preparing a conductive reinforcement layer on the side of the back electrode away from the battery substrate, the conductive reinforcement layer is also prepared on the side of the overlapping portion away from the battery substrate.

[0026] In some embodiments of the present disclosure, the conductive enhancement layer includes a metal foil, and the step of preparing the conductive enhancement layer on the side of the back electrode away from the battery substrate includes: welding the metal foil to the back electrode.

[0027] In some embodiments of the present disclosure, the conductive enhancement layer includes metal coating, and the step of preparing the conductive enhancement layer on the side of the back electrode away from the battery substrate includes: coating the metal coating on the back electrode.

[0028] In some embodiments of the present disclosure, the conductive enhancement layer includes a conductive adhesive, and the step of preparing the conductive enhancement layer on the side of the back electrode away from the battery substrate includes: pasting the conductive adhesive on the back electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a schematic structural diagram of a battery substrate and a backlight surface of a back electrode;

[0030] FIG2 is a schematic diagram of a structure in which a conductive reinforcement layer is provided on the basis of the structure shown in FIG1 ;

[0031] FIG3 is a schematic structural diagram of the light-facing side of the battery substrate shown in FIG1 ;

[0032] FIG4 is a schematic diagram of a structure in which a conductive reinforcement layer is provided on the basis of the structure shown in FIG1 ;

[0033] FIG5 is a schematic diagram of a structure in which a conductive reinforcement layer is provided on the basis of the structure shown in FIG1 ;

[0034] FIG6 is a schematic diagram of a structure in which a conductive reinforcement layer is provided on the basis of the structure shown in FIG1 ;

[0035] FIG7 is a schematic structural diagram of a portion of connectors provided on the backlight surface of the battery substrate shown in FIG1 ;

[0036] FIG8 is a schematic structural diagram of a portion of connectors provided on the light-facing surface of the battery substrate shown in FIG3 ;

[0037] FIG9 is a schematic diagram of the back structure of a photovoltaic module;

[0038] FIG10 is a schematic structural diagram of a battery substrate and a backlight surface of a back electrode;

[0039] FIG11 is a schematic structural diagram of the light-facing side of the battery substrate shown in FIG10;

[0040] FIG12 is a schematic structural diagram of the backlight surface of a solar cell including the structure shown in FIG10;

[0041] FIG13 is a schematic diagram of the back structure of a photovoltaic module including a plurality of solar cells in FIG12;

[0042] Among them, the various figure numbers and their meanings are as follows: 100, battery substrate; 110, back electrode; 120, conductive reinforcement layer; 121, conductive part; 122, connecting part; 130, front electrode; 210, connector; 211, overlapping part; 221, back contact pad; 222, front contact pad. DETAILED DESCRIPTION

[0043] To facilitate understanding of the present disclosure, a more comprehensive description of the present disclosure will be provided below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present disclosure. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure pertains. The terms used herein in the specification of this disclosure are for the purpose of describing specific embodiments only and are not intended to limit this disclosure. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items, and "more than" as used herein includes two or more items.

[0045] In this article, unless otherwise indicated, each reaction step may be carried out in the order in which it is presented, or may be carried out out of the order in which it is presented. For example, other steps may be included between each reaction step, and the order of the reaction steps may be appropriately reversed. This is something that can be determined by a skilled person based on conventional knowledge and experience. Preferably, the reaction methods described herein are carried out sequentially.

[0046] The present disclosure provides a solar cell. Figure 1 is a schematic diagram of the structure of a solar cell substrate 100 and a back electrode 110 on the backlight side. Referring to Figure 1 , the solar cell includes a solar cell substrate 100 and a back electrode 110. The solar cell substrate 100 has a light-facing side and a backlight side that are oppositely disposed, and there are multiple back electrodes 110. Multiple back electrodes 110 are disposed on the backlight side of the solar cell substrate 100.

[0047] In this disclosure, the terms "light-facing surface" and "backlight surface" are used solely to distinguish the locations of two opposing surfaces of a cell substrate. In actual operation, the "light-facing surface" is the surface of the cell substrate that primarily receives light, but the "backlight surface" does not necessarily exclude light. On the contrary, due to diffuse reflections and other factors, the "backlight surface" may also receive light in actual operation.

[0048] In some examples of this embodiment, the back electrode 110 may include a main gate electrode and a fine gate electrode connected to the main gate electrode. Alternatively, the back electrode 110 may include only the main gate electrode or the fine gate electrode.

[0049] Referring to Figure 2, Figure 2 is a schematic diagram of a structure in which a conductive enhancement layer 120 is provided on the basis of the structure shown in Figure 1. The dotted area in Figure 2 represents the back electrode 110 located below the conductive enhancement layer 120. The conductive enhancement layer 120 is provided on the side of the back electrode 110 away from the backlight surface. The conductive enhancement layer 120 is connected to the plurality of back electrodes 110 and covers part or all of the backlight surface of the cell substrate 100.

[0050] In conventional technology, solar cells are often only provided with grid electrodes on the backlight side. Even if one wants to increase the electrical conductivity of the grid electrodes, consideration is often given only to the material, shape, and arrangement of the grid electrodes. Furthermore, conventional technology uses grid electrodes in order to simultaneously utilize both the sun-facing and backlight sides of the solar cell for power generation, which also results in current photovoltaic modules being generally bifacial modules. However, according to the actual research of this application, in many practical application fields, the benefits of backlight-side power generation are almost negligible. Accordingly, the poor electrical conductivity of the backlight-side grid electrodes leads to more significant module power losses.

[0051] The solar cell provided by the present disclosure takes a different approach. An additional conductive enhancement layer 120 is provided on the backlight surface. Multiple back electrodes 110 are connected through the conductive enhancement layer 120. The current therein can be transmitted through the conductive enhancement layer 120, which can effectively reduce the series resistance between the multiple back electrodes 110, thereby effectively improving the actual conversion efficiency and output power of the solar cell and the module.

[0052] Referring to Figure 3, Figure 3 is a schematic structural diagram of the light-facing surface of the cell substrate 100 shown in Figure 1. In some examples of this embodiment, the solar cell further includes a front electrode 130, which can be disposed on the light-facing surface of the cell substrate 100. In this embodiment, the polarity of the front electrode 130 and the back electrode 110 can be opposite.

[0053] In some examples of this embodiment, the front electrode 130 may include a main gate electrode and a fine gate electrode connected to the main gate electrode. Alternatively, the front electrode 130 may include only the main gate electrode or the fine gate electrode.

[0054] It can be understood that a solar cell generally includes a positive electrode and a negative electrode, and one of the front electrode 130 and the back electrode 110 can serve as the positive electrode, and the other can serve as the negative electrode.

[0055] 1 to 3 , in this embodiment, the conductive reinforcement layer 120 may be in the shape of an elongated strip as a whole. The elongated conductive reinforcement layer 120 may extend from one side of the battery substrate 100 to the other opposite side.

[0056] As shown in Figures 1 to 3 , in some examples of this embodiment, there are multiple back electrodes 110, and the multiple back electrodes 110 are arranged in parallel, and the back electrodes 110 are arranged in sequence. Furthermore, each back electrode 110 can extend in the same direction, and the extension direction of the conductive reinforcement layer 120 can intersect with the extension direction of the back electrodes 110, so that the conductive reinforcement layer 120 can contact multiple back electrodes 110 simultaneously.

[0057] As shown in Figures 1 to 3 , in some examples of this embodiment, the area ratio of the backlight surface covered by the conductive reinforcement layer 120 to the entire backlight surface is greater than 50%. For example, the area ratio of the backlight surface covered by the conductive reinforcement layer 120 to the entire backlight surface is 50%, 60%, 70%, 80%, 90%, 92%, 95%, 99%, or 100%. Alternatively, the area ratio of the backlight surface covered by the conductive reinforcement layer 120 to the entire backlight surface can also be between any two of the above area ratios. By setting the area of ​​the backlight surface covered by the conductive reinforcement layer 120 to be higher, the series resistance between the back electrodes 110 can be significantly reduced, further improving the conversion efficiency and output power of the solar cell.

[0058] In some examples of this embodiment, the conductive enhancement layer 120 may include a metal. Using metal as the material for the conductive enhancement layer 120 not only reduces the resistance between the multiple back electrodes 110 but also provides better barrier properties, preventing contaminants such as water vapor from directly contacting the back electrodes 110 and the cell substrate 100, thereby extending the service life of the solar cell. Furthermore, using metal as the material for the conductive enhancement layer 120 exhibits full-spectrum reflectivity, with a high reflectivity for mid- and long-wave infrared radiation, thereby increasing short-circuit current.

[0059] In some examples of this embodiment, the thermal conductivity of the conductive reinforcement layer 120 can be higher than the thermal conductivity of the cell substrate 100. By using a conductive reinforcement layer 120 with a higher thermal conductivity, the heat dissipation performance of the solar cell during operation is improved, the operating temperature of the solar cell is reduced, and the actual power generation effect and output power of the solar cell are further improved.

[0060] In some examples of this embodiment, the material of the conductive reinforcement layer 120 may include one or more of gold, silver, copper, aluminum, and tin.

[0061] Furthermore, in some examples of this embodiment, the material of the conductive reinforcement layer 120 may be selected from metal materials, and the metal material may be a single metal or an alloy.

[0062] In some examples of this embodiment, the conductive reinforcement layer 120 may include metal foil, metal paint, or metal conductive adhesive. Furthermore, the metal foil may be attached to the back electrode 110 and the battery substrate 100 by gluing or welding, the metal paint may be attached to the back electrode 110 and the battery substrate 100 by coating, and the conductive adhesive may be attached to the back electrode 110 and the battery substrate 100 by gluing.

[0063] In some examples of this embodiment, the thickness of the conductive reinforcement layer 120 can be 5 μm to 100 μm. For example, the thickness of the conductive reinforcement layer 120 can be 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, or 100 μm. Alternatively, the thickness of the conductive reinforcement layer 120 can be within a range between any two of the aforementioned thicknesses. By setting the thickness of the conductive reinforcement layer 120 to 5 μm to 100 μm, the weight of the solar cell can be reduced while ensuring good conductivity and saving material costs.

[0064] FIG4 is a schematic diagram of a structure in which a conductive enhancement layer 120 is provided on the basis of the structure shown in FIG1. ​​Referring to FIG4 , the conductive enhancement layer 120 is provided on the side of the back electrode 110 away from the backlight surface. The conductive enhancement layer 120 is connected to the plurality of back electrodes 110 and covers a portion of the backlight surface of the cell substrate 100.

[0065] 4 , in this embodiment, the conductive reinforcement layer 120 includes a plurality of spaced apart conductive portions 121 , each of which is in the shape of a strip. Furthermore, the strip-shaped conductive portion 121 may extend from one side of the battery substrate 100 to the opposite side.

[0066] As shown in Figure 4, in some examples of this embodiment, there are multiple back electrodes 110, and the multiple back electrodes 110 are arranged in parallel, and the back electrodes 110 are arranged in sequence. Furthermore, the back electrodes 110 can extend in the same direction, and the extension direction of each conductive portion 121 can intersect with the extension direction of the back electrodes 110, so that each conductive portion 121 can contact multiple back electrodes 110 at the same time.

[0067] 4 , in this embodiment, a plurality of conductive portions 121 may be arranged in parallel.

[0068] As shown in FIG. 4 , in some examples of this embodiment, among the plurality of conductive portions 121 , any two conductive portions 121 are not connected.

[0069] FIG5 is a schematic diagram illustrating a structure in which a conductive enhancement layer 120 is provided on the structure shown in FIG1 . Referring to FIG5 , the conductive enhancement layer 120 is provided on the side of the back electrode 110 away from the backlight surface. The conductive enhancement layer 120 is connected to multiple back electrodes 110 and covers a portion of the backlight surface of the cell substrate 100.

[0070] 5 , in this embodiment, the conductive reinforcement layer 120 includes a plurality of spaced apart conductive portions 121 , each of which is in the shape of a strip. Furthermore, the strip-shaped conductive portion 121 may extend from one side of the battery substrate 100 to the opposite side.

[0071] As shown in Figure 5, in some examples of this embodiment, there are multiple back electrodes 110, and the multiple back electrodes 110 are arranged in parallel, and the back electrodes 110 are arranged in sequence. Furthermore, the back electrodes 110 can extend in the same direction, and the extension direction of each conductive portion 121 can intersect with the extension direction of the back electrodes 110, so that each conductive portion 121 can contact multiple back electrodes 110 at the same time.

[0072] 5 , in this embodiment, a plurality of conductive portions 121 may be arranged in parallel.

[0073] 5 , in some examples of this embodiment, the conductive reinforcement layer 120 may further include a connecting portion 122 . The connecting portion 122 is disposed between two adjacent conductive portions 121 , and the two adjacent conductive portions 121 may be connected via the connecting portion 122 .

[0074] FIG6 is a schematic diagram of a structure in which a conductive reinforcement layer 120 is provided on the basis of the structure shown in FIG1 . The dotted area in FIG6 represents the back electrode 110 located below the conductive reinforcement layer 120. Referring to FIG6 , the conductive reinforcement layer 120 is provided on the side of the back electrode 110 away from the backlight surface. The conductive reinforcement layer 120 is connected to the plurality of back electrodes 110 and covers a portion of the backlight surface of the cell substrate 100.

[0075] 6 , in some examples of this embodiment, the number of the conductive portions 121 may correspond to the number of the back electrodes 110 , and each conductive portion 121 covers the corresponding back electrode 110 .

[0076] As shown in FIG6 , in some examples of this embodiment, the width of the conductive portion 121 can be greater than or equal to the width of the back electrode 110 and completely cover the back electrode 110 to further improve the efficiency of the solar cell. In other examples, the conductive portion 121 can also only partially cover the back electrode 110. By having the conductive portion 121 cover the back electrode 110, the series resistance between the multiple back electrodes 110 can also be further reduced.

[0077] Furthermore, the present disclosure also provides a method for preparing a solar cell, which includes the following steps S1.1 to S1.2.

[0078] Step S1.1: providing a battery substrate 100 and preparing a plurality of back electrodes 110 on the backlight surface of the battery substrate 100.

[0079] The cell substrate 100 refers to the portion of the solar cell that does not contain electrodes and can generate carriers under the action of light.

[0080] In some examples of this embodiment, the solar cell may be a crystalline silicon cell. Accordingly, the cell substrate 100 may include a silicon substrate and a functional structure disposed on the silicon substrate. The functional structure may be selected based on the specific type of solar cell. Typically, the functional structure may include a doped layer stacked on the silicon substrate, where the doping type of the doped layer is opposite to that of the silicon substrate.

[0081] In some examples of this embodiment, the step of preparing a plurality of back electrodes 110 on the backlight surface of the battery substrate 100 may include: preparing a conductive paste on the backlight surface of the battery substrate 100 and performing a sintering process to form the back electrodes 110. The conductive paste may be prepared by screen printing, and the conductive paste may be a conductive silver paste.

[0082] Step S1.2: preparing a conductive enhancement layer 120 on the side of the back electrode 110 away from the battery substrate 100.

[0083] In some examples of this embodiment, the conductive enhancement layer 120 may include metal foil, and the step of preparing the conductive enhancement layer 120 on the side of the back electrode 110 away from the battery substrate 100 includes: pasting or welding the metal foil on the back electrode 110 and the battery substrate 100.

[0084] In some examples of this embodiment, the metal foil may be a pure metal, which may be selected from a single metal or a metal alloy.

[0085] In some examples of this embodiment, the conductive enhancement layer 120 includes metal coating, and the step of preparing the conductive enhancement layer 120 on the side of the back electrode 110 away from the battery substrate 100 includes: applying the metal coating on the back electrode 110 and the battery substrate 100 .

[0086] The metallic coating material may have fluidity before being applied. For example, the metallic coating material may be metallic paint.

[0087] In some examples of this embodiment, the conductive enhancement layer 120 includes conductive glue, and the step of preparing the conductive enhancement layer 120 on the side of the back electrode 110 away from the battery substrate 100 includes: sticking the conductive glue on the back electrode 110 and the battery substrate 100.

[0088] In the above examples, the use of metal foil as the conductive reinforcement layer 120 significantly improves the overall conductivity of the conductive reinforcement layer 120 compared to other conductive reinforcement layers 120. In this embodiment, the photovoltaic module may include the solar cell of the above embodiment, and there may be multiple solar cells, with adjacent solar cells electrically connected.

[0089] Furthermore, in some examples of this embodiment, the photovoltaic module may include a connector 210, and two adjacent solar cells may be electrically connected via the connector 210. FIG7 is a schematic diagram of a structure in which a portion of the connector 210 is provided on the backlight surface of the cell substrate 100 shown in FIG1 , and FIG8 is a schematic diagram of a structure in which a portion of the connector 210 is provided on the light-facing surface of the cell substrate 100 shown in FIG3 . It will be understood that, between two adjacent solar cells, the portion of the connector 210 located on the backlight surface of one solar cell may be connected to the portion of the connector 210 located on the light-facing surface of the other solar cell, thereby electrically connecting the two adjacent solar cells.

[0090] 7 , the connector 210 may include a lap portion 211 disposed on the backlight surface. The lap portion 211 may be disposed on the back electrode 110 and cover at least a portion of the back electrode 110. In conjunction with FIG7 and FIG8 , in some examples of this embodiment, the lap portion 211 may be located on the backlight surface of one solar cell, and the end of the connector 210 away from the lap portion 211 may be disposed on the light-facing surface of another adjacent solar cell. Furthermore, the connector 210 may be disposed on the front electrode 130 and cover at least a portion of the front electrode 130. In other embodiments, the lap portion 211 may not cover the back electrode 110, but may be connected to the back electrode 120 through the conductive enhancement layer 120.

[0091] Figure 9 is a schematic diagram of the back structure of a photovoltaic module. Referring to Figure 9 , it can be understood that the photovoltaic module may include multiple solar cells, and in two adjacent solar cells, the connector 210 may be connected to the front electrode 130 of one solar cell and the back electrode 110 of the other adjacent solar cell.

[0092] In some examples of this embodiment, the conductive reinforcement layer 120 may cover at least a portion of the overlap portion 211. By also providing the conductive reinforcement layer 120 on the overlap portion 211, the conductivity between two adjacent solar cells can be further improved, thereby improving the overall conversion efficiency and output power of the photovoltaic module.

[0093] Furthermore, the present disclosure also provides a method for preparing a photovoltaic module as shown in FIG9 , which includes the following steps S2.1 to S2.3.

[0094] Step S2.1: providing a plurality of battery substrates 100 and preparing a plurality of back electrodes 110 on the backlight surface of each battery substrate 100.

[0095] The cell substrate 100 refers to the portion of the solar cell that does not contain electrodes and can generate carriers under the action of light.

[0096] In some examples of this embodiment, the solar cell may be a crystalline silicon cell. Accordingly, the cell substrate 100 may include a silicon substrate and a functional structure disposed on the silicon substrate. The functional structure may be selected based on the specific type of solar cell. Typically, the functional structure may include a doped layer stacked on the silicon substrate, where the doping type of the doped layer is opposite to that of the silicon substrate.

[0097] In some examples of this embodiment, the step of preparing a plurality of back electrodes 110 on the backlight surface of the battery substrate 100 may include: preparing a conductive paste on the backlight surface of the battery substrate 100 and performing a sintering process to form the back electrodes 110. The conductive paste may be prepared by screen printing, and the conductive paste may be a conductive silver paste.

[0098] In some examples of this embodiment, the method for preparing a photovoltaic module may further include the step of preparing a front electrode 130 on the light-facing surface of the cell substrate 100. The step of preparing the front electrode 130 may include: preparing a conductive paste on the light-facing surface of the cell substrate 100 and performing a sintering process to form the front electrode 130. The conductive paste may be prepared by screen printing, and the conductive paste may be a conductive silver paste.

[0099] Step S2.2: Use a connector 210 to electrically connect two adjacent battery substrates 100 .

[0100] 7 and 8 , in some examples of this embodiment, the connector 210 may include a lap portion 211 disposed on the backlight surface of the cell substrate 100 . The lap portion 211 may be electrically connected to the back electrode 110 .

[0101] It can be understood that the connector 210 can be provided on two adjacent battery substrates 100 and electrically connected to the front electrode 130 on one of the battery substrates 100 and the back electrode 110 on the other battery substrate 100 .

[0102] In some examples of this embodiment, in the step of electrically connecting two adjacent battery substrates 100 using a connector 210, the connector 210 may comprise metal and be welded to the back electrodes 110 of the battery substrates 100.

[0103] In some examples of this embodiment, in the step of electrically connecting two adjacent battery substrates 100 using the connector 210, the end of the connector 210 away from the overlapping portion 211 can be welded to the front electrode 130 of the other battery substrate 100.

[0104] Step S2.3: preparing a conductive reinforcement layer 120 on the back electrode 110 and the overlapping portion 211 .

[0105] The conductive reinforcement layer 120 may be disposed on a side of the back electrode 110 and the overlapping portion 211 that is away from the battery substrate 100, and the conductive reinforcement layer 120 may be electrically connected to the back electrode 110 and the overlapping portion 211. For example, the conductive reinforcement layer 120 may cover the back electrode 110 and the overlapping portion 211, so that the back electrode 110 and the overlapping portion 211 are electrically connected.

[0106] In some examples of this embodiment, the conductive enhancement layer 120 may include metal foil, and the step of preparing the conductive enhancement layer 120 on the side of the back electrode 110 away from the battery substrate 100 includes: pasting or welding the metal foil on the back electrode 110 and the battery substrate 100.

[0107] In some examples of this embodiment, the metal foil may be a pure metal, which may be selected from a single metal or a metal alloy.

[0108] In some examples of this embodiment, the conductive enhancement layer 120 includes metal coating, and the step of preparing the conductive enhancement layer 120 on the side of the back electrode 110 away from the battery substrate 100 includes: applying the metal coating on the back electrode 110 and the battery substrate 100 .

[0109] The metallic coating material may have fluidity before being applied. For example, the metallic coating material may be metallic paint.

[0110] In some examples of this embodiment, the conductive enhancement layer 120 includes conductive glue, and the step of preparing the conductive enhancement layer 120 on the side of the back electrode 110 away from the battery substrate 100 includes: sticking the conductive glue on the back electrode 110 and the battery substrate 100.

[0111] It can be understood that through steps S2.1 to S2.3, the photovoltaic module shown in Figure 9 can be prepared. The provision of the conductive reinforcement layer 120 on both the back electrode 110 and the connector 210 not only reduces the transmission resistance between the back electrode 110 but also effectively reduces the contact resistance between the back electrode 110 and the connector 210. Furthermore, the conductive reinforcement layer 120 can improve the bonding strength between the back electrode 110, the connector 210, and the cell substrate 100, thereby making the structure of the photovoltaic module more stable.

[0112] 10 is a schematic structural diagram of a battery substrate 100 and a backside electrode 110. As shown in FIG10 , there can be multiple backside electrodes 110, and multiple backside electrodes 110 are disposed on the backside of the battery substrate 100.

[0113] As shown in Figure 10, in some examples of this embodiment, the photovoltaic module may include a back contact pad 221 arranged on the backlight surface of the cell substrate 100, the back contact pad 221 is electrically connected to the back electrode 110, and the back contact pad 221 can be arranged close to the edge of the cell substrate 100.

[0114] Figure 11 is a schematic structural diagram of the light-facing surface of the cell substrate 100 shown in Figure 10. Referring to Figure 11, in some examples of this embodiment, the solar cell further includes a front electrode 130, which can be disposed on the light-facing surface of the cell substrate 100. In this embodiment, the polarity of the front electrode 130 and the back electrode 110 can be opposite.

[0115] As shown in Figure 11, in some examples of this embodiment, the solar cell may include a front contact pad 222 arranged on the light-facing surface of the cell substrate 100, the front contact pad 222 is electrically connected to the front electrode 130, the front contact pad 222 can be arranged close to the end of the cell substrate 100, and the end to which the front contact pad 222 is close can be arranged opposite to the end to which the back contact pad 221 is close.

[0116] Figure 12 is a schematic diagram of the backlight surface of a solar cell having the structure shown in Figure 10. Referring to Figure 12 , the solar cell includes a conductive enhancement layer 120, which is disposed on a side of the back electrode 110 away from the backlight surface. The conductive enhancement layer 120 is connected to multiple back electrodes 110 and covers part or all of the backlight surface of the cell substrate 100.

[0117] 12 , in some examples of this embodiment, the conductive reinforcement layer 120 covers a portion of the backlight surface of the cell substrate 100 , and the back contact pads 221 are exposed from the conductive reinforcement layer 120 . Furthermore, multiple back contact pads 221 are exposed from the conductive reinforcement layer 120 .

[0118] Figure 13 is a schematic diagram of the back structure of a photovoltaic module including multiple solar cells shown in Figure 12. Referring to Figure 12, multiple solar cells are arranged in parallel, and two adjacent solar cells can directly contact each other via the front contact pad 222 and the back contact pad 221, thereby electrically connecting the two adjacent solar cells.

[0119] 13 , in some examples of this embodiment, in two adjacent solar cells, the front contact pad 222 of one solar cell may contact the back contact pad 221 of the other solar cell, so that the two adjacent solar cells are connected in series.

[0120] It is understood that the photovoltaic module shown in Figure 13 can be prepared by referring to, for example, steps S2.1 to S2.3. The difference is that the photovoltaic module shown in Figure 13 does not include connector 210, and therefore, there is no need to additionally provide connector 210 during the preparation process. Furthermore, during the preparation of the photovoltaic module, the back electrode 110 and the front electrode 130 can be first prepared on each cell substrate 100, and then the multiple cell substrates 100 are connected in a predetermined manner. The conductive reinforcement layer 120 can be prepared after the connection between two adjacent cell substrates 100 is completed.

[0121] Furthermore, the present disclosure also provides the following embodiments and comparative examples. Through the following embodiments and comparative examples, the advantages of the photovoltaic module of the present disclosure will become more apparent.

[0122] The battery substrates used in the following examples and comparative examples were prepared as follows:

[0123] An n-type silicon wafer is provided as a silicon substrate.

[0124] A front intrinsic amorphous silicon layer and a back intrinsic amorphous silicon layer are deposited on the front and back of the silicon substrate respectively.

[0125] A p-type doped amorphous silicon layer and an n-type doped amorphous silicon layer are deposited on the front and back sides of the silicon substrate respectively.

[0126] In addition, a front transparent conductive layer and a back transparent conductive layer are respectively formed on the front and back sides of the silicon substrate to serve as battery substrates.

[0127] Example 1

[0128] 132 battery substrates are provided, and the front electrode and the back electrode are respectively screen-printed on the front and back of each battery substrate to form a solar cell.

[0129] A welding ribbon is used as a connecting piece, and the welding ribbon is welded to two adjacent solar cells to connect the two adjacent solar cells in series.

[0130] A copper foil with a thickness of 60 μm is covered on the back of the battery substrate and welded to the back electrode and the welding strip on the back. The copper foil covers the entire back of the battery substrate.

[0131] Example 2

[0132] 132 battery substrates are provided, and the front electrode and the back electrode are respectively screen-printed on the front and back of each battery substrate to form a solar cell.

[0133] A welding ribbon is used as a connecting piece, and the welding ribbon is welded to two adjacent solar cells to connect the two adjacent solar cells in series.

[0134] A metal paint with a thickness of 40 μm is coated on the back of the battery substrate. The metal paint covers the back electrode and the welding strip on the back, and covers the entire back of the battery substrate.

[0135] Example 3

[0136] 132 battery substrates are provided, and the front electrode and the back electrode are respectively screen-printed on the front and back of each battery substrate to form a solar cell.

[0137] A welding ribbon is used as a connecting piece, and the welding ribbon is welded to two adjacent solar cells to connect the two adjacent solar cells in series.

[0138] A conductive adhesive with a thickness of 30 μm is pasted on the back of the battery substrate. The conductive adhesive covers the back electrode and the soldering strip on the back, and covers the entire back of the battery substrate.

[0139] Example 4

[0140] 132 battery substrates are provided, and the front electrode and the back electrode are respectively screen-printed on the front and back of each battery substrate to form a solar cell.

[0141] A welding ribbon is used as a connecting piece, and the welding ribbon is welded to two adjacent solar cells to connect the two adjacent solar cells in series.

[0142] A copper foil with a thickness of 60 μm is covered on the back of the battery substrate and welded to the back electrode. The copper foil covers 50% of the backlight area of ​​the battery substrate.

[0143] Example 5

[0144] 132 battery substrates are provided, and the front electrode and the back electrode are respectively screen-printed on the front and back of each battery substrate to form a solar cell.

[0145] A copper foil with a thickness of 60 μm is covered on 50% of the backlight area of ​​the battery substrate, and part of the back electrode is not shielded by the copper foil.

[0146] A welding ribbon is used as a connecting piece, which is welded to two adjacent solar cells to connect the two adjacent solar cells in series. The welding ribbon is set on the cell substrate that is not shielded by the copper foil.

[0147] Comparative Example 1

[0148] 132 battery substrates are provided, and the front electrode and the back electrode are respectively screen-printed on the front and back of each battery substrate to form a solar cell.

[0149] A welding ribbon is used as a connecting piece, and the welding ribbon is welded to two adjacent solar cell sheets to connect the two adjacent solar cells in series.

[0150] Experiment: The light conversion efficiency of each of the above photovoltaic modules was tested. The results can be seen in Table 1.

[0151] Table 1

[0152] As shown in Table 1, Examples 1 to 5 all have a conductive enhancement layer set on the back electrode of the battery substrate, so that at least part of the back of the battery substrate is shielded by the conductive enhancement layer. Comparative Example 1 does not have a conductive enhancement layer set on the back electrode, so the back of the battery substrate is exposed and can receive light. Although the back of Comparative Example 1 can also receive sunlight, the conductive enhancement layer set on the back of the battery substrate in Examples 1 to 5 results in a reduction in the area of ​​the back receiving light. However, the light conversion efficiency of Comparative Example 1 is still lower than that of Examples 1 to 5. This is mainly because the conductive enhancement layer set in Examples 1 to 5 can significantly improve the conductivity between the back electrodes, thereby reducing the transmission loss of carriers. This is greater than the gain in the final conversion efficiency due to the larger light-receiving area in Comparative Example 1. Therefore, the conversion efficiency of the photovoltaic modules of Examples 1 to 5 can be improved.

[0153] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0154] The above embodiments merely illustrate several implementations of the present disclosure, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the scope of the present disclosure, all of which fall within the scope of protection of the present disclosure. Therefore, the scope of protection of the patent disclosed herein shall be determined by the appended claims.

Claims

1. A solar cell, comprising a cell substrate, a back electrode and a conductive enhancement layer, wherein the cell substrate has a light-facing surface and a backlight surface that are arranged opposite to each other, there are multiple back electrodes, and the multiple back electrodes are arranged on the backlight surface of the cell substrate, the conductive enhancement layer is arranged on the side of the back electrode away from the backlight surface, the conductive enhancement layer is connected to the multiple back electrodes, and the conductive enhancement layer covers at least part of the backlight surface of the cell substrate. The solar cell according to claim 1 , wherein the material of the conductive enhancement layer comprises metal. 3 . The solar cell according to claim 2 , wherein the conductive enhancement layer comprises a metal foil, and the metal foil is welded to the back electrode. 4 . The solar cell according to claim 2 , wherein the conductive enhancement layer comprises a metal coating, and the metal coating is coated on the back electrode. 5 . The solar cell according to claim 2 , wherein the conductive enhancement layer comprises a conductive adhesive, and the conductive adhesive is adhered to the back electrode. 6 . The solar cell according to claim 1 , wherein the thickness of the conductive enhancement layer is 5 μm to 100 μm. 7 . The solar cell according to claim 1 , wherein the thermal conductivity of the conductive enhancement layer is higher than the thermal conductivity of the cell substrate.

8. The solar cell according to any one of claims 1 to 7, wherein the conductive enhancement layer covers the entire backlight surface of the cell substrate.

9. The solar cell according to any one of claims 1 to 7, wherein the conductive enhancement layer covers a portion of the backlight surface of the cell substrate. 10 . The solar cell according to claim 9 , wherein the conductive enhancement layer comprises a plurality of conductive portions disposed at intervals, the conductive portions are in the shape of long strips, and an extension direction of the conductive portions intersects an extension direction of the back electrode.

11. The solar cell according to claim 9, wherein the conductive enhancement layer comprises a plurality of conductive portions arranged at intervals, the number of the conductive portions corresponds to the number of the back electrodes, and each of the conductive portions covers the corresponding back electrode. 12 . The solar cell according to claim 8 , wherein the area ratio of the backlight surface covered by the conductive reinforcement layer to the entire backlight surface is greater than 50%.

13. A photovoltaic module, comprising a plurality of solar cells according to any one of claims 1 to 12, wherein two adjacent solar cells are electrically connected.

14. The photovoltaic module according to claim 13, further comprising a connector, wherein two adjacent solar cells are electrically connected via the connector, wherein the connector comprises an overlap portion disposed on the backlight surface, and wherein the conductive reinforcement layer also covers at least a portion of the overlap portion.

15. The photovoltaic module according to claim 13, further comprising a front contact pad arranged on the light-facing surface of the cell substrate and a back contact pad arranged on the back-lighting surface of the cell substrate, wherein in two adjacent solar cells, the front contact pad in one of the solar cells is aligned and in contact with the back contact pad in the other solar cell.

16. A method for preparing a photovoltaic module, comprising the following steps: Providing a plurality of battery substrates, and preparing a plurality of back electrodes on the backlight surface of each of the battery substrates; connecting a plurality of said battery substrates; and, A conductive enhancement layer is prepared on the side of the back electrode away from the battery substrate.

17. The method for preparing a photovoltaic module according to claim 16, wherein in the step of connecting two adjacent battery substrates, the two adjacent battery substrates are connected by a connecting member, wherein the connecting member comprises an overlap portion provided on the backlight surface of the battery substrate; In the step of preparing a conductive reinforcement layer on the side of the back electrode away from the battery substrate, the conductive reinforcement layer is also prepared on the side of the overlapping portion away from the battery substrate.

18. The method for preparing a photovoltaic module according to any one of claims 16 to 17, wherein the conductive reinforcement layer comprises a metal foil, and the step of preparing the conductive reinforcement layer on the side of the back electrode away from the battery substrate comprises: The metal foil is welded to the back electrode.

19. The method for preparing a photovoltaic module according to any one of claims 16 to 17, wherein the conductive enhancement layer comprises a metal coating, and the step of preparing the conductive enhancement layer on the side of the back electrode away from the battery substrate comprises: The metal coating is applied on the back electrode.

20. The method for preparing a photovoltaic module according to any one of claims 16 to 17, wherein the conductive reinforcement layer comprises a conductive adhesive, and the step of preparing the conductive reinforcement layer on the side of the back electrode away from the battery substrate comprises: The conductive adhesive is pasted on the back electrode.

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