Back contact solar cell, preparation method thereof and photovoltaic module

Abstract

The invention relates to the technical field of back contact solar cells, in particular to a back contact solar cell, a preparation method thereof and a photovoltaic module. The back contact solar cell comprises a silicon substrate, a light-transmitting adhesive layer and a light-transmitting protective film. The silicon substrate is provided with a light receiving surface, and the light receiving surface is provided with a suede structure. The light-transmitting adhesive layer is arranged on the surface, away from the silicon substrate, of the suede structure and fills the suede structure. And the light-transmitting protective film is adhered to one surface, deviating from the silicon substrate, of the light-transmitting adhesive layer. The light-transmitting protective film of the back contact solar cell is adhered to the light receiving surface through the light-transmitting adhesive layer, and the protective structure formed by the light-transmitting protective film and the light-transmitting adhesive layer plays a role in protecting the suede structure, so that the suede structure is prevented from being damaged in the production and transportation processes of the back contact solar cell and the manufacturing process of a photovoltaic module; and the conversion efficiency of the back contact solar cell can be maintained.

Description

Technical Field

[0001] This application relates to the field of back-contact solar cell technology, and in particular to a back-contact solar cell and its preparation method, and a photovoltaic module. Background Technology

[0002] In back-contact solar cells, the metal electrodes are all located on the back side, while the light-receiving side is unshielded by metal electrodes, thus reducing optical losses. To further improve the performance of back-contact solar cells, a textured surface is provided on the light-receiving side. During production, transportation, and module fabrication, the textured surface on the light-receiving side is easily damaged due to the lack of metal electrode protection, which can affect the conversion efficiency of the back-contact solar cell. Summary of the Invention

[0003] This application discloses a back-contact solar cell and its preparation method, as well as a photovoltaic module, which can prevent the textured surface structure from being damaged during the production, transportation, and photovoltaic module manufacturing process of the back-contact solar cell, thereby helping to maintain the conversion efficiency of the back-contact solar cell.

[0004] To achieve the above objectives, in a first aspect, embodiments of this application disclose a back-contact solar cell, comprising:

[0005] A silicon substrate having a light-receiving surface, wherein a textured surface is provided on the light-receiving surface;

[0006] A light-transmitting adhesive layer, wherein the light-transmitting adhesive layer is disposed on the side of the textured structure opposite to the silicon substrate and fills the textured structure; and

[0007] A light-transmitting protective film is adhered to the side of the light-transmitting adhesive layer that faces away from the silicon substrate.

[0008] In one possible implementation of the first aspect, the back-contact solar cell further includes:

[0009] An insulating adhesive layer is provided, and the silicon substrate further has a backlight surface, which is disposed opposite to the light-receiving surface. The insulating adhesive layer is disposed on the backlight surface. Both the insulating adhesive layer and the light-transmitting adhesive layer are configured to be formed by curing and shrinking.

[0010] In one possible implementation of the first aspect, the back-contact solar cell further includes:

[0011] A first doped layer is disposed on the backlight surface;

[0012] The second doped layer is provided with the first doped layer and the second doped layer alternately spaced, and the first doped layer and the second doped layer have opposite conductivity types;

[0013] A first electrode, disposed on the backlight surface and in ohmic contact with the first doped layer; and

[0014] The second electrode is disposed on the backlight surface and in ohmic contact with the second doped layer; the insulating adhesive layer covers the first electrode and / or the second electrode, and the insulating adhesive layer is configured to isolate the first electrode and the second electrode.

[0015] In one possible implementation of the first aspect, the velvet structure is a pyramid structure, the pyramid structure having a apex;

[0016] In the height direction of the pyramid structure, the surface of the light-transmitting adhesive layer facing away from the light-receiving surface is higher than the pyramid tip.

[0017] In one possible implementation of the first aspect, the thickness of the light-transmitting adhesive layer is 15 μm to 20 μm;

[0018] And / or, the light-transmitting adhesive layer is made of a transparent material;

[0019] And / or, the light-transmitting adhesive layer is an epoxy-based adhesive layer or an organosilicon-based adhesive layer;

[0020] And / or, the light-transmitting protective film is made of a transparent material;

[0021] And / or, the light-transmitting protective film is a PET film or a POE film;

[0022] And / or, the thickness of the light-transmitting protective film is 0.245mm to 0.255mm;

[0023] And / or, the area of ​​the light-transmitting protective film is smaller than the area of ​​the light-transmitting adhesive layer;

[0024] And / or, the light-transmitting protective film is provided with a plurality of hollow structures.

[0025] In one possible implementation of the first aspect, the back-contact solar cell further includes:

[0026] A functional film is formed-formally grown on the side of the textured structure facing away from the silicon substrate; a light-transmitting adhesive layer is disposed on the side of the functional film facing away from the silicon substrate.

[0027] Secondly, embodiments of this application disclose a method for preparing a back-contact solar cell as described in the first aspect, comprising the following steps:

[0028] An adhesive is applied to the side of the textured structure facing away from the silicon substrate; wherein the adhesive fills the textured structure.

[0029] A light-transmitting protective film is applied to the side of the adhesive that faces away from the silicon substrate.

[0030] The adhesive is transformed into the light-transmitting adhesive layer.

[0031] In a possible implementation of the second aspect, the step of applying the adhesive to the surface of the textured structure opposite to the silicon substrate includes:

[0032] The adhesive is printed on the side of the textured structure opposite to the silicon substrate using a printing screen; wherein the printing screen has an ink-transmitting area, the ink-transmitting area being smaller than the size of the silicon substrate;

[0033] And / or, the viscosity of the adhesive is 15000 mPa·s to 20000 mPa·s;

[0034] And / or, the adhesive is an epoxy-based adhesive, which includes an epoxy resin component and a first curing agent component, wherein the weight ratio of the epoxy resin component to the first curing agent component is (9-19):1; or, the adhesive is a silicone-based adhesive, which includes a silicone-based adhesive component and a second curing agent component, wherein the weight ratio of the silicone-based adhesive component to the second curing agent component is 1:(1-3).

[0035] In a possible implementation of the second aspect, the preparation method further includes the following steps:

[0036] Insulating adhesive is printed on the backlight surface of the silicon substrate;

[0037] The silicon substrate printed with the insulating adhesive is heated; wherein the insulating adhesive cures and shrinks to form an insulating adhesive layer;

[0038] The step of converting the adhesive into the light-transmitting adhesive layer includes:

[0039] The silicon substrate to which the adhesive is applied is heated; wherein the adhesive cures and shrinks to form the light-transmitting adhesive layer.

[0040] Thirdly, embodiments of this application disclose a photovoltaic module, including a plurality of solar cells connected in series and / or in parallel, wherein at least one of the solar cells is a back-contact solar cell according to the first aspect, or at least one of the solar cells is a back-contact solar cell prepared according to the preparation method of the second aspect.

[0041] In a possible implementation of the third aspect, the photovoltaic module further includes a module end film, which is stacked on the side of the light-transmitting protective film facing away from the silicon substrate, and the thickness of the module end film is 0.295mm to 0.305mm.

[0042] Compared with existing technologies, the advantages of this application are as follows: The light-transmitting protective film of the back-contact solar cell is bonded to the light-receiving surface via a light-transmitting adhesive layer. The protective structure formed by the light-transmitting protective film and the light-transmitting adhesive layer protects the textured surface structure, preventing damage during the production, transportation, and photovoltaic module fabrication of the back-contact solar cell, thereby helping to maintain the conversion efficiency of the back-contact solar cell. Furthermore, bonding the light-transmitting protective film with the light-transmitting adhesive layer makes the protective film more firmly bonded to the textured surface structure, resulting in a more robust structure that maintains the integrity of the back-contact solar cell. This facilitates on-site inspection of the back-contact solar cell and reduces secondary scratches. Moreover, when the back-contact solar cell is fabricated into a photovoltaic module, the light-transmitting protective film allows for thinning of the adhesive film at the module end, thus protecting the textured surface structure while also reducing material costs. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1A This is a schematic diagram of the structure of a back-contact solar cell disclosed in an embodiment of this application;

[0045] Figure 1B for Figure 1A A schematic diagram of the forces acting on a silicon substrate;

[0046] Figure 2 This is a schematic diagram of the structure of the light-transmitting protective film disclosed in the embodiments of this application;

[0047] Figure 3 This is a schematic diagram illustrating the step of printing adhesive on the side of the textured structure facing away from the silicon substrate using a printing screen, as disclosed in an embodiment of this application.

[0048] Figure 4 This is a schematic diagram of the structure of the printing screen disclosed in the embodiments of this application;

[0049] Figure 5 This is a schematic diagram comparing the dimensions of the ink-permeable area and the silicon substrate disclosed in the embodiments of this application;

[0050] Figure 6 This is a schematic diagram of the step of covering a light-transmitting protective film on the side of the adhesive facing away from the silicon substrate, as disclosed in an embodiment of this application;

[0051] Figure 7 This is a schematic diagram of the structure of the photovoltaic module disclosed in the embodiments of this application.

[0052] Explanation of reference numerals in the attached figures:

[0053] 100. Back contact solar cell; 110. Silicon substrate; 111. Light-receiving surface; 112. Textured structure; 1121. Spiral; 113. Backlighting surface; 120. Transparent adhesive layer; 130. Transparent protective film; 131. Hollowed-out structure; 140. First doped layer; 150. Second doped layer; 160. Insulating adhesive layer; 170a. First electrode; 170b. Second electrode; 180. Back passivation layer; 190. Functional film; 200. Photovoltaic module; 210. Module end film; 220. Encapsulation film; 230. Transparent panel; 240. Backsheet; 250. Frame; 300. Printing screen; 310. Ink-transparent area; 400. Adhesive; 500. Squeegee; 600. Mechanical gripper; 700. Cutter. Detailed Implementation

[0054] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0055] In this application, the terms "upper," "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to be constructed and operated in a specific orientation.

[0056] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0057] Furthermore, the terms "set up" and "equipped with" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0058] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0059] Back-contact solar cells lack the protection of metal electrodes on their light-receiving surface. During transportation, testing, and processing, the textured surface and functional films such as passivation and anti-reflection coatings grown on it are easily damaged by friction and impact, thus affecting the conversion efficiency of the back-contact solar cells. An effective textured surface protection structure is currently lacking in related technologies.

[0060] Based on the above analysis, this application provides a back-contact solar cell, in which a protective structure composed of a light-transmitting protective film and a light-transmitting adhesive layer protects the textured surface structure, preventing damage to the textured surface structure during the production, transportation, and photovoltaic module manufacturing of the back-contact solar cell, thereby helping to maintain the conversion efficiency of the back-contact solar cell.

[0061] The technical solution of the present invention will now be described in conjunction with the embodiments and accompanying drawings.

[0062] Firstly, see [the following] Figure 1A This application discloses a back-contact solar cell 100, including a silicon substrate 110, a light-transmitting adhesive layer 120, and a light-transmitting protective film 130. The silicon substrate 110 has a light-receiving surface 111, on which a textured structure 112 is disposed. The light-transmitting adhesive layer 120 is disposed on the side of the textured structure 112 facing away from the silicon substrate 110 and fills the textured structure 112. The light-transmitting protective film 130 is adhered to the side of the light-transmitting adhesive layer 120 facing away from the silicon substrate 110.

[0063] The light-transmitting protective film 130 of the back contact solar cell 100 is bonded to the light-receiving surface 111 via a light-transmitting adhesive layer 120. The protective structure formed by the light-transmitting protective film 130 and the light-transmitting adhesive layer 120 protects the textured structure 112, preventing damage to the textured structure 112 during the production, transportation, and photovoltaic module manufacturing of the back contact solar cell 100, thereby helping to maintain the conversion efficiency of the back contact solar cell 100. Furthermore, by bonding the light-transmitting protective film 130 to the textured structure 112 via the light-transmitting adhesive layer 120, the light-transmitting protective film 130 is more firmly bonded to the textured structure 112, providing the textured structure 112 with protection against mechanical scratches or mechanical friction. Moreover, when the back contact solar cell 100 is manufactured into a photovoltaic module, the light-transmitting protective film 130 facilitates the thinning of the adhesive film at the module end, thus protecting the textured structure 112 while also reducing material costs.

[0064] In some embodiments, please combine Figure 1A and Figure 1B The back-contact solar cell 100 also includes an insulating adhesive layer 160. The silicon substrate 110 also has a backlight surface 113, which is disposed opposite to the light-receiving surface 111, and the insulating adhesive layer 160 is disposed on the backlight surface 113. Both the insulating adhesive layer 160 and the light-transmitting adhesive layer 120 are configured to be formed by curing shrinkage.

[0065] The back-contact solar cell 100 uses an insulating adhesive layer 160 to insulate the metallized conductive structure on the back surface, reducing leakage. However, the insulating adhesive layer 160 is formed through curing shrinkage, which refers to the volume reduction phenomenon that occurs during the curing process of the adhesive. For example, the curing shrinkage of the insulating adhesive layer 160 causes warping of the silicon substrate 110 in one direction, such as... Figure 1B As shown in the F2 direction, warping can affect the structural stability of the back contact solar cell 100, and may even damage it. This application specifically designs the transparent adhesive layer 120 to be formed through curing and shrinkage. Since the insulating adhesive layer 160 and the transparent adhesive layer 120 are located on two opposing surfaces, namely the backlight surface 113 and the light-receiving surface 111, the curing and shrinkage of the transparent adhesive layer 120 causes warping of the silicon substrate 110 in one of the directions shown in the image. Figure 1B The F1 direction shown is opposite to the F2 direction. In the silicon substrate 110, the stress caused by the curing shrinkage of the light-transmitting adhesive layer 120 at least partially offsets the stress caused by the insulating adhesive layer 160, thereby reducing the warpage of the back contact solar cell 100. Accordingly, the light-transmitting protective film 130 may also have the characteristic of shrinking after heating.

[0066] Furthermore, referring to the return Figure 1A The back-contact solar cell 100 further includes a first doped layer 140, a second doped layer 150, a first electrode 170a, and a second electrode 170b. The first doped layer 140 is disposed on the backlight surface. The first doped layer 140 and the second doped layer 150 are alternately arranged, and the conductivity types of the first doped layer 140 and the second doped layer 150 are opposite. For example, one of the first doped layer 140 and the second doped layer 150 is an N-type doped layer and the other is a P-type doped layer. The first doped layer 140 and the second doped layer 150 can be doped polycrystalline silicon layers, or doped layers formed directly on the backlight surface 113 of the silicon substrate 110 through atomic diffusion, such as boron diffusion or phosphorus diffusion. The first electrode 170a is disposed on the backlight surface and is in ohmic contact with the first doped layer 140. The second electrode 170b is disposed on the backlight surface and is in ohmic contact with the second doped layer 150. An insulating adhesive layer 160 covers the first electrode 170a and / or the second electrode 170b, and the insulating adhesive layer 160 is configured to isolate the first electrode 170a and the second electrode 170b. See also Figure 1AFor example, in one cross-section, the insulating adhesive layer 160 covers the sub-gate of the second electrode 170b, while the sub-gate of the first electrode 170a is exposed. Alternatively, in other cross-sections, the insulating adhesive layer covers the sub-gate of the first electrode, while the sub-gate of the second electrode is exposed. Or, both the main gates of the first and second electrodes are covered by the insulating adhesive layer. In other words, the insulating adhesive layer 160 has various pattern arrangements to achieve isolation between the first electrode 170a and the second electrode 170b.

[0067] Optionally, the back-contact solar cell 100 further includes a back passivation layer 180. The back passivation layer 180 covers the back surface 113 and the side of the first doped layer 140 and the second doped layer 150 facing away from the silicon substrate 110. The first electrode 170a and the second electrode 170b pass through the back passivation layer 180 and then make ohmic contact with the first doped layer 140 and the second doped layer 150, respectively.

[0068] In some embodiments, the textured structure 112 is a pyramid structure, with a apex 1121. The apex 1121 refers to the sharp portion of the pyramid structure away from the silicon substrate 110, and the base refers to the end of the pyramid structure opposite to the apex 1121. The height direction of the pyramid structure refers to the direction opposite to the base. The height direction of the pyramid structure is as follows: Figure 1A In the Z0-Z1 direction shown, along the height of the pyramid structure, the surface of the light-transmitting adhesive layer 120 facing away from the light-receiving surface 111 is higher than the pyramid tip 1121. Optionally, the surface of the light-transmitting adhesive layer 120 facing away from the light-receiving surface 111 is 5μm to 50μm higher than the pyramid tip. In other words, the light-transmitting adhesive layer 120 is immersed in the pyramid structure. The light-transmitting protective film 130 is adhered to the light-transmitting adhesive layer 120 at all points, rather than directly contacting the pyramid tip 1121. This improves the adhesion of the light-transmitting adhesive layer 120 and avoids the light-transmitting protective film 130 directly contacting the pyramid tip 1121 and damaging the pyramid tip 1121.

[0069] Preferably, the thickness of the translucent adhesive layer 120 is 15μm to 20μm, including any value within this thickness range, such as 15μm, 18μm, or 20μm. It is understood that since the velvet structure 112 is a surface structure composed of protrusions or depressions, the thickness of the translucent adhesive layer 120 is variable. The above-mentioned thickness range of the translucent adhesive layer 120 ensures that the translucent adhesive layer 120 is fully immersed in the velvet structure 112 while also saving on manufacturing materials.

[0070] Preferably, the light-transmitting adhesive layer 120 is made of a transparent material to reduce light absorption.

[0071] Preferably, the translucent adhesive layer 120 is an epoxy-based adhesive layer or a silicone-based adhesive layer. Epoxy-based adhesive layers have good coatability, allowing for bonding and coating over a longer period of time. Epoxy-based adhesive layers typically exhibit very high bond strength in their thermocured state, and also possess good weather resistance.

[0072] Preferably, the light-transmitting protective film 130 is made of a transparent material to reduce the absorption of light.

[0073] Preferably, the light-transmitting protective film 130 is a PET (Polyethylene Terephthalate) film or a POE (Polyolefin Elastomer) film.

[0074] Preferably, the thickness of the light-transmitting protective film 130 is 0.245 mm to 0.255 mm, including any value within this thickness range, such as 0.245 mm, 0.25 mm, or 0.255 mm. The light-transmitting protective film 130 within this thickness range can effectively protect the textured structure 112, and it can also reduce the thickness requirement of the encapsulant film at the module end. In other words, a composite film of suitable thickness can be formed by combining a thinned module end encapsulant film with the light-transmitting protective film 130 within this thickness range for encapsulating the back contact solar cell 100 at the module end.

[0075] Preferably, the area of ​​the light-transmitting protective film 130 is smaller than the area of ​​the light-transmitting adhesive layer 120. When the light-transmitting protective film 130 is pasted onto the velvet structure 112, even if there is a misalignment, it will not affect the overall pasting of the light-transmitting protective film 130 onto the light-transmitting adhesive layer 120, thereby reducing the difficulty of the process. For example, the length and width of the light-transmitting protective film 130 are 5mm to 15mm smaller than the length and width of the light-transmitting adhesive layer 120, respectively.

[0076] Preferably, see Figure 2 A plurality of perforated structures 131 are provided on the light-transmitting protective film 130. The function of the perforated structures 131 is to adjust the curing shrinkage degree of the light-transmitting protective film 130. For example, by adjusting the ratio of the total area of ​​the perforated structures 131 to the area of ​​the light-transmitting protective film 130, the curing shrinkage degree of the light-transmitting protective film 130 is adjusted. By adjusting the curing shrinkage degree of the light-transmitting protective film 130, the light-transmitting protective film 130 and the insulating adhesive layer 160 have the same curing shrinkage degree, further balancing the warping stress between the light-transmitting protective film 130 and the light-transmitting adhesive layer 120 on the light-receiving side and the insulating adhesive layer 160 on the back-light-receiving side of the back-contact solar cell 100. Optionally, the perforated structure 131 can be a perforated hole or a perforated groove. It should be noted that, although in Figure 2The diagram only shows the hollow structure 131 as square, but the shape of the hollow structure 131 can also be any shape such as circle or polygon. Preferably, there are multiple hollow structures 131, and the multiple hollow structures 131 are arranged in a uniform distribution.

[0077] In some embodiments, the back-contact solar cell 100 further includes a functional film 190, which is conformally grown on the side of the textured structure 112 facing away from the silicon substrate 110. In other words, the surface of the functional film 190 is also textured. A light-transmitting adhesive layer 120 is disposed on the side of the functional film 190 facing away from the silicon substrate 110, and the protective structure composed of the light-transmitting adhesive layer 120 and the light-transmitting protective film 130 protects the functional film 190 of the textured structure 112. Optionally, the functional film 190 may be a passivation film and / or an anti-reflection film, for example, the functional film 190 includes an aluminum oxide film and a silicon nitride film sequentially stacked facing away from the silicon substrate 110.

[0078] Secondly, embodiments of this application disclose a method for preparing a back-contact solar cell as described in the first aspect, comprising the following steps:

[0079] An adhesive is applied to the side of the textured structure facing away from the silicon substrate; wherein the adhesive fills the textured structure;

[0080] A light-transmitting protective film is applied to the side of the adhesive that faces away from the silicon substrate;

[0081] Transform the adhesive into a translucent adhesive layer.

[0082] The preparation method is simple to operate, and the process of applying adhesive first and then covering with a light-transmitting protective film can also reduce the damage to the velvet structure during the preparation process.

[0083] In some embodiments, the step of applying an adhesive to the side of the textured structure facing away from the silicon substrate includes:

[0084] Adhesive is printed on the side of the textured surface facing away from the silicon substrate using a printing screen.

[0085] For example, please see Figure 3 During printing, the adhesive 400 is located on the upper surface of the printing screen 300, and the textured structure on the light-receiving surface 111 of the back contact solar cell 100 corresponds to the lower surface of the printing screen 300. When the squeegee 500 contacts the upper surface of the printing screen 300 and moves relative to the printing screen 300, the adhesive 400 penetrates through the printing screen 300 to the lower surface of the printing screen 300 and is transferred to the textured structure.

[0086] The printing method for adhesives allows for precise control over the adhesive thickness and printed patterns, while also effectively protecting the textured surface during the manufacturing process.

[0087] Among them, see Figure 4 and Figure 5 The printing screen 300 has an ink-permeable area 310, which is smaller than the size of the silicon substrate 110. The size of the textured surface is the same as the size of the silicon substrate 110, allowing the adhesive to cover and fill the entire textured surface through printing. For example, when both the silicon substrate 110 and the ink-permeable area 310 are square, the side length of the ink-permeable area 310 is 5mm to 20mm shorter than the side length of the silicon substrate 110. For instance, if the size of the silicon substrate 110 is 182mm × 182mm, the size of the ink-permeable area 310 is 170mm × 170mm.

[0088] Preferably, the viscosity of the adhesive is 15000 mPa·s to 20000 mPa·s, including any value within this viscosity range, such as 15000 mPa·s, 18000 mPa·s, or 20000 mPa·s. Adhesives within this viscosity range are beneficial for improving the smoothness of screen printing.

[0089] Preferably, the adhesive is an epoxy-based adhesive, comprising an epoxy resin component and a first curing agent component, wherein the weight ratio of the epoxy resin component to the first curing agent component is (9-19):1, including any value within this weight ratio range, such as 9:1, 14:1, or 19:1; or, the adhesive is a silicone-based adhesive, comprising a silicone-based adhesive component and a second curing agent component, wherein the weight ratio of the silicone-based adhesive component and the second curing agent component is 1:(1-3), including any value within this weight ratio range, such as 1:1, 1:2, or 1:3. The above weight ratio can be adjusted according to the adhesion of the light-transmitting protective film, thereby controlling the curing speed and crosslinking density of the adhesive, and thus meeting the printing requirements of the printing screen.

[0090] In some embodiments, the preparation method further includes the following steps:

[0091] Insulating adhesive is printed on the backlight surface of a silicon substrate;

[0092] A silicon substrate printed with insulating adhesive is heated; wherein, the insulating adhesive cures and shrinks to form an insulating adhesive layer;

[0093] The steps for converting an adhesive into a translucent adhesive layer include:

[0094] A silicon substrate with an adhesive applied is heated; wherein the adhesive cures and shrinks to form a light-transmitting adhesive layer.

[0095] Alternatively, the adhesive and the insulating adhesive are preferably cured by heat separately. The stress generated during the heat curing process of the adhesive at least partially offsets the stress generated during the heat curing process of the insulating adhesive, thereby reducing the warpage of the back contact solar cell.

[0096] In some embodiments, see Figure 6 The step of coating the adhesive side away from the silicon substrate with a light-transmitting protective film includes:

[0097] Unwind the roll of the light-transmitting protective film;

[0098] Clamp the end of the roll of light-transmitting protective film and align the light-transmitting protective film with the light-receiving surface; for example, clamp the end of the roll of light-transmitting protective film 130 with a mechanical gripper 600.

[0099] Cut the appropriate length of the light-transmitting protective film from the roll of light-transmitting protective film; for example, cut the appropriate length of the light-transmitting protective film 130 using cutter 700;

[0100] The cut-off light-transmitting protective film is pasted onto the adhesive on the light-receiving surface 111 of the back contact solar cell 100.

[0101] Thirdly, see Figure 7 This application discloses a photovoltaic module 200, including a plurality of solar cells connected in series and / or in parallel, wherein at least one solar cell is a back-contact solar cell 100 as described in the first aspect, or at least one solar cell is a back-contact solar cell 100 prepared according to the preparation method described in the second aspect.

[0102] In a possible implementation of the third aspect, the photovoltaic module 200 further includes a module-end encapsulating film 210, which is stacked on the side of the light-transmitting protective film 130 facing away from the silicon substrate 110. The thickness of the module-end encapsulating film 210 is 0.295 mm to 0.305 mm, including any value within this thickness range, such as 0.295 mm, 0.3 mm, or 0.305 mm. Before the back-contact solar cell 100 of this application is manufactured into a photovoltaic module 200, a light-transmitting protective film 130 is attached to the light-receiving surface. The light-transmitting protective film 130 protects the textured surface structure during the production, transportation, and testing of the cell. At the module end, the light-transmitting protective film 130 also facilitates the thinning of the module-end encapsulating film 210, thereby saving material costs. For example, the composite film consisting of the 0.3mm thick component end film 210 and the 0.25mm thick light-transmitting protective film 130 has a total thickness of 0.55mm, which is comparable to the thickness of the component end film (0.55mm) required in related technologies. Preferably, the light-transmitting protective film and the component end film are made of the same material.

[0103] Optionally, the photovoltaic module 200 further includes an encapsulating film 220, a light-transmitting panel 230, a backsheet 240, and a frame 250. The encapsulating film 220 is disposed on the back surface of the back contact solar cell 100. The backsheet 240 is stacked on the side of the encapsulating film 220 away from the back contact solar cell 100. The light-transmitting panel 230 is stacked on the side of the module end film 210 away from the back contact solar cell 100, thereby forming a stacked structure composed of the backsheet 240, the encapsulating film 220, the back contact solar cell 100, the module end film 210, and the light-transmitting panel 230. The frame 250 is disposed around the edge of the stacked structure.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A back-contact solar cell, characterized in that, include: A silicon substrate having a light-receiving surface, wherein a textured surface is provided on the light-receiving surface; A light-transmitting adhesive layer is disposed on the side of the textured structure opposite to the silicon substrate and fills the textured structure; as well as A light-transmitting protective film is adhered to the side of the light-transmitting adhesive layer that faces away from the silicon substrate.

2. The back-contact solar cell according to claim 1, characterized in that, The back-contact solar cell also includes: An insulating adhesive layer is provided, and the silicon substrate further has a backlight surface, which is disposed opposite to the light-receiving surface. The insulating adhesive layer is disposed on the backlight surface. Both the insulating adhesive layer and the light-transmitting adhesive layer are configured to be formed by curing and shrinking.

3. The back-contact solar cell according to claim 2, characterized in that, The back-contact solar cell also includes: A first doped layer is disposed on the backlight surface; The second doped layer is provided with the first doped layer and the second doped layer alternately spaced, and the first doped layer and the second doped layer have opposite conductivity types; A first electrode, disposed on the backlight surface and in ohmic contact with the first doped layer; and The second electrode is disposed on the backlight surface and in ohmic contact with the second doped layer; the insulating adhesive layer covers the first electrode and / or the second electrode, and the insulating adhesive layer is configured to isolate the first electrode and the second electrode.

4. The back-contact solar cell according to claim 1, characterized in that, The velvet structure is a pyramid structure, and the pyramid structure has a apex; In the height direction of the pyramid structure, the surface of the light-transmitting adhesive layer facing away from the light-receiving surface is higher than the pyramid tip.

5. The back-contact solar cell according to any one of claims 1 to 4, characterized in that, The thickness of the light-transmitting adhesive layer is 15μm to 20μm; And / or, the light-transmitting adhesive layer is made of a transparent material; And / or, the light-transmitting adhesive layer is an epoxy-based adhesive layer or an organosilicon-based adhesive layer; And / or, the light-transmitting protective film is made of a transparent material; And / or, the light-transmitting protective film is a PET film or a POE film; And / or, the thickness of the light-transmitting protective film is 0.245mm to 0.255mm; And / or, the area of ​​the light-transmitting protective film is smaller than the area of ​​the light-transmitting adhesive layer; And / or, the light-transmitting protective film is provided with a plurality of hollow structures.

6. The back-contact solar cell according to any one of claims 1 to 4, characterized in that, The back-contact solar cell also includes: A functional film is formed-formally grown on the side of the textured structure facing away from the silicon substrate; a light-transmitting adhesive layer is disposed on the side of the functional film facing away from the silicon substrate.

7. A method for preparing a back-contact solar cell as described in any one of claims 1 to 6, characterized in that, Includes the following steps: An adhesive is applied to the side of the textured structure facing away from the silicon substrate; wherein the adhesive fills the textured structure. A light-transmitting protective film is applied to the side of the adhesive that faces away from the silicon substrate. The adhesive is transformed into the light-transmitting adhesive layer.

8. The method for preparing a back-contact solar cell according to claim 7, characterized in that, The step of applying adhesive to the side of the textured structure opposite to the silicon substrate includes: The adhesive is printed on the side of the textured structure opposite to the silicon substrate using a printing screen; wherein the printing screen has an ink-transmitting area, the ink-transmitting area being smaller than the size of the silicon substrate; And / or, the viscosity of the adhesive is 15000 mPa·s to 20000 mPa·s; And / or, the adhesive is an epoxy-based adhesive, which includes an epoxy resin component and a first curing agent component, wherein the weight ratio of the epoxy resin component to the first curing agent component is (9-19):1; or, the adhesive is a silicone-based adhesive, which includes a silicone-based adhesive component and a second curing agent component, wherein the weight ratio of the silicone-based adhesive component to the second curing agent component is 1:(1-3).

9. The method for preparing a back-contact solar cell according to claim 7 or 8, characterized in that, The preparation method further includes the following steps: Insulating adhesive is printed on the backlight surface of the silicon substrate; The silicon substrate printed with the insulating adhesive is heated; wherein the insulating adhesive cures and shrinks to form an insulating adhesive layer; The step of converting the adhesive into the light-transmitting adhesive layer includes: The silicon substrate to which the adhesive is applied is heated; wherein the adhesive cures and shrinks to form the light-transmitting adhesive layer.

10. A photovoltaic module, characterized in that, The solar cell comprises a plurality of solar cells connected in series and / or in parallel, wherein at least one of the solar cells is a back-contact solar cell according to any one of claims 1 to 6, or at least one of the solar cells is a back-contact solar cell prepared by the preparation method according to any one of claims 7 to 9.

11. The photovoltaic module according to claim 10, characterized in that, The photovoltaic module also includes a module end film, which is stacked on the side of the light-transmitting protective film facing away from the silicon substrate, and the thickness of the module end film is 0.295mm to 0.305mm.

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