Back adhesive film, manufacturing method thereof and photovoltaic module

Abstract

The invention relates to the photovoltaic field, and discloses a back adhesive film and a manufacturing method thereof, and a photovoltaic module, and the method comprises the steps: preparing a first adhesive film layer and a second adhesive film layer; forming a hollow area on the metal foil to obtain a latticed metal foil; wherein the width of the peripheral frame of the hollow area is greater than the gap between the adjacent battery pieces; the first adhesive film layer, the latticed metal foil and the second adhesive film layer are sequentially stacked and heated, so that the first adhesive film layer and the second adhesive film layer are melted, and a composite film layer of the first adhesive film layer, the latticed metal foil and the second adhesive film layer is formed and serves as a back adhesive film. The latticed metal foil is formed in the back adhesive film, the water permeability of the latticed metal foil is almost zero, water vapor can be prevented from directly invading the battery piece, the transmission path of the water vapor in the back adhesive film is prolonged, and then corrosion of the water vapor to the battery piece is weakened or isolated. And by adopting a heating melting mode, the first adhesive film layer and the second adhesive film layer have better viscosity with the latticed metal foil, and are combined more tightly, so that gaps are avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaics, and in particular to a back adhesive film, a manufacturing method thereof and a photovoltaic module. BACKGROUND

[0002] A single-glass photovoltaic module includes, from bottom to top, a back substrate, a back adhesive film, a cell layer, a front adhesive film and a front glass substrate. For the front side, the front glass substrate plays an important role in allowing light to pass through and blocking water vapor, oxygen and structural load. For the back side, the back adhesive film and the back substrate play a role in blocking water vapor, oxygen and ultraviolet light.

[0003] The back substrate and the back adhesive film are both organic materials. The back substrate is usually made of PET (polyethylene terephthalate) or polyolefin material. The water vapor transmission rate of the back substrate is 0.5-2 g / m 2 ·d, and the water vapor transmission rate of the adhesive film is 5-30 g / m 2 ·d (36℃), which is greater than the water vapor transmission rate of glass (0 g / m 2 ·d). Therefore, it is impossible to completely block water vapor, which may cause the surface of some water vapor-sensitive cells (such as HJT (Hereto-junction with Intrinsic Thin-layer), TOPCon (Tunnel Oxide Passivating Contacts) cells, perovskite laminates, etc.) to corrode and power to decrease due to water vapor penetration, thereby failing to achieve single-glass packaging.

[0004] Therefore, how to solve the above technical problems should be the focus of attention of those skilled in the art. SUMMARY

[0005] The purpose of the present application is to provide a back adhesive film, a manufacturing method thereof and a photovoltaic module to avoid water vapor from corroding the cells and improve the power of the photovoltaic module.

[0006] To solve the above technical problems, the present application provides a manufacturing method of a back adhesive film, comprising:

[0007] preparing a first adhesive film layer and a second adhesive film layer;

[0008] forming a hollow area on the metal foil to obtain a grid-shaped metal foil; wherein the width of the frame around the hollow area is greater than the gap between adjacent cells;

[0009] stacking the first adhesive film layer, the mesh-shaped metal foil and the second adhesive film layer in sequence and heating, melting the first adhesive film layer and the second adhesive film layer, forming a composite film layer of the first adhesive film layer, the mesh-shaped metal foil and the second adhesive film layer as a back adhesive film.

[0010] Optionally, before forming the mesh-shaped metal foil by forming the hollowed-out area on the metal foil, further comprising:

[0011] forming a light-reflecting structure on the surface of the metal foil.

[0012] Optionally, forming the light-reflecting structure on the surface of the metal foil comprises:

[0013] forming the light-reflecting structure on the surface of the metal foil by rolling or stamping.

[0014] Optionally, the width of the frame around the hollowed-out area is not less than 2mm.

[0015] Optionally, when stacking the first adhesive film layer, the mesh-shaped metal foil and the second adhesive film layer in sequence and heating, the heating temperature ranges from 75℃ to 150℃.

[0016] Optionally, preparing the first adhesive film layer and the second adhesive film layer comprises:

[0017] mixing the raw materials of the first adhesive film layer and the second adhesive film layer respectively and uniformly;

[0018] placing the uniformly mixed first adhesive film layer raw materials and the second adhesive film layer raw materials respectively in a screw extruder, to obtain the processed first adhesive film layer material and the processed second adhesive film layer material respectively;

[0019] placing the processed first adhesive film layer material and the processed second adhesive film layer material respectively in a casting machine, to form the to-be-processed first adhesive film layer and the to-be-processed second adhesive film layer respectively;

[0020] solidifying the to-be-processed first adhesive film layer and the to-be-processed second adhesive film layer respectively, to obtain the first adhesive film layer and the second adhesive film layer respectively.

[0021] Optionally, when the first adhesive film layer and / or the second adhesive film layer is an EVA adhesive film layer, the raw materials for preparing the EVA adhesive film layer comprise:

[0022] Ethylene-vinyl acetate copolymer with a mass fraction of greater than or equal to 98%, octadecanol-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate with a mass fraction ranging from 0.03 to 0.1%, bis(1,2,2,6,6-pentamethylpiperidinyl) sebacate with a mass fraction ranging from 0.03 to 0.2%, triallyl isocyanurate with a mass fraction ranging from 0.3 to 1%, ethoxylated trimethylolpropane tripropylate with a mass fraction ranging from 0.1 to 1%, carbon peroxo acid-O,O-91,1-dimethylpropyl)-O-(2-ethylhexyl) ester with a mass fraction ranging from 0.1 to 0.5%, t-butyl peroxy carbonic acid-2-ethylhexyl ester with a mass fraction ranging from 0.3 to 0.8%, 3-(methacryloyl)propyl trimethoxysilane with a mass fraction ranging from 0.05 to 0.5%, and vinyl triethoxysilane with a mass fraction ranging from 0.05 to 0.2%.

[0023] Optionally, when the first adhesive film layer and / or the second adhesive film layer is a POE adhesive film layer, the raw materials for preparing the POE adhesive film layer include: ethylene-butene copolymer with a mass fraction of greater than or equal to 98%, octadecanol-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate with a mass fraction ranging from 0.03 to 0.1%, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate with a mass fraction ranging from 0.03 to 0.3%, triallyl isocyanurate with a mass fraction ranging from 0.3 to 1%, carbon peroxo acid-O,O-91,1-dimethylpropyl)-O-(2-ethylhexyl) ester with a mass fraction ranging from 0.02 to 0.8%, t-butyl peroxy carbonic acid-2-ethylhexyl ester with a mass fraction ranging from 0.3 to 0.8%, vinyl trimethoxysilane with a mass fraction ranging from 0.01 to 0.2%, vinyl triethoxysilane with a mass fraction ranging from 0.05 to 0.3%, and triethoxypentylsilane with a mass fraction ranging from 0.1 to 0.4%.

[0024] Optionally, forming the hollowed-out area on the metal foil includes:

[0025] Forming the hollowed-out area on the metal foil by stamping.

[0026] The application also provides a back adhesive film prepared by the above-mentioned method for preparing a back adhesive film.

[0027] Optionally, the first adhesive film layer in the back adhesive film includes any one of a POE adhesive film layer, an EVA adhesive film layer, a PVB adhesive film layer, a silicone adhesive layer, and a composite adhesive film layer; and the second adhesive film layer includes any one of a POE adhesive film layer, an EVA adhesive film layer, a PVB adhesive film layer, a silicone adhesive layer, and a composite adhesive film layer.

[0028] This application also provides a photovoltaic module, which includes the back film described in any of the above descriptions.

[0029] The present application provides a method for manufacturing a back adhesive film, comprising: preparing a first adhesive film layer and a second adhesive film layer; forming a hollow area on a metal foil to obtain a grid-like metal foil; wherein the width of the perimeter of the hollow area is greater than the gap between adjacent battery cells; sequentially stacking the first adhesive film layer, the grid-like metal foil, and the second adhesive film layer and heating them to melt the first adhesive film layer and the second adhesive film layer, thereby forming a composite film layer of the first adhesive film layer, the grid-like metal foil, and the second adhesive film layer as the back adhesive film.

[0030] As can be seen, in this application, the composite structure film formed by the first adhesive film layer, the mesh-like metal foil, and the second adhesive film layer is used as the back adhesive film. The width of the perimeter of the hollowed-out area in the mesh-like metal foil is greater than the gap between adjacent solar cells, resulting in near-zero water permeability. When water vapor invades from the back of the photovoltaic module, it can prevent direct penetration of the solar cells, extending the water vapor transport path within the back adhesive film, thereby reducing or isolating water vapor from corroding the solar cells. The hollowed-out area in the mesh-like metal foil reduces the amount of metal foil used, lowering manufacturing costs. Furthermore, the composite of the first adhesive film layer, the mesh-like metal foil, and the second adhesive film layer is achieved through heating and melting, resulting in better adhesion between the first and second adhesive film layers and the mesh-like metal foil. This also allows the first and second adhesive film layers to become fluid, resulting in a tighter bond with the mesh-like metal foil and preventing gaps.

[0031] In addition, this application also provides a backing film and a photovoltaic module having the above-mentioned advantages. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0033] Figure 1 This is a schematic diagram illustrating the intrusion of water vapor into a single-glass photovoltaic module in related technologies.

[0034] Figure 2 The process of a method for manufacturing a back adhesive film provided in the embodiments of this application Figure One ;

[0035] Figure 3 A schematic diagram of a mesh-like metal foil provided in an embodiment of this application;

[0036] Figure 4 The process of a method for manufacturing a back adhesive film provided in the embodiments of this application Figure Two ;

[0037] Figure 5 This is a schematic diagram illustrating moisture intrusion when the back adhesive film in this application is used in a photovoltaic module;

[0038] Figure 6 This is a partial schematic diagram of a photovoltaic module provided in an embodiment of this application;

[0039] In the figure, 1 is the back substrate, 2 is the back adhesive film, 3 is the battery cell layer, 4 is the front adhesive film, 5 is the front glass substrate, 21 is the first adhesive film layer, 22 is the second adhesive film layer, 23 is the mesh-like metal foil, 231 is the cutout area, and 232 is the frame. Detailed Implementation

[0040] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0042] A schematic diagram of water vapor intrusion into a single-glass photovoltaic module in related technologies is shown below. Figure 1 As shown, the photovoltaic module includes a back substrate 1, a back encapsulant film 2, a cell layer 3, a front encapsulant film 4, and a front glass substrate 5. Both the back substrate 1 and the back encapsulant film 2 are organic materials. Moisture vapor passes through the back substrate 1 and the back encapsulant film 2 from the back, causing corrosion to the metal grid lines on the front of the cell, which in turn leads to a decrease in module power.

[0043] In view of this, this application provides a method for manufacturing a back adhesive film, please refer to... Figure 2 ,include:

[0044] Step S101: Prepare the first adhesive film layer and the second adhesive film layer.

[0045] The first adhesive film layer includes, but is not limited to, any one of POE (Polyolefin elastomer), EVA (Ethylene Vinyl Acetate Copolymer), PVB (Polyvinylbutyral), silicone rubber, and composite adhesive film layers; the second adhesive film layer includes, but is not limited to, any one of POE, EVA, PVB, silicone rubber, and composite adhesive film layers. The first and second adhesive film layers may be the same or different, both within the scope of protection of this application.

[0046] The first and second adhesive film layers can be purchased directly or prepared by oneself.

[0047] As one possible implementation, preparing the first adhesive film layer and the second adhesive film layer includes:

[0048] Step S1011: Mix the raw materials for preparing the first adhesive film layer and the second adhesive film layer evenly.

[0049] Step S1012: Place the uniformly mixed first film layer raw material and second film layer raw material into a screw extruder to obtain the treated first film layer material and the treated second film layer material respectively.

[0050] In this step, the screw extruder can be a twin-screw extruder.

[0051] Step S1013: Place the treated first adhesive film layer material and the treated second adhesive film layer material into a casting machine to form the first adhesive film layer to be treated and the second adhesive film layer to be treated.

[0052] Step S1014: Cure the first adhesive film layer to be treated and the second adhesive film layer to be treated respectively to obtain the first adhesive film layer and the second adhesive film layer.

[0053] The specific operation process of steps S1011 to S1014 is well known to those skilled in the art, and will not be described in detail here.

[0054] As one possible implementation, when the first adhesive film layer and / or the second adhesive film layer are EVA adhesive film layers, the raw materials for preparing the EVA adhesive film layer include:

[0055] The composition includes, by weight, 98% or more of ethylene-vinyl acetate copolymer, 0.03-0.1% of octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 0.03-0.2% of bis(1,2,2,6,6-pentamethylpiperidinol) sebacate, 0.3-1% of triallyl isocyanurate, and 0.1-1% of ethoxytrimethylolpropionate. The mixture comprises: alkyltripropane triacrylate, carboperoxy acid (O,O-91,1-dimethylpropyl)-O-(2-ethylhexyl) ester (0.1-0.5% by mass), tert-butyl peroxycarbonate-2-ethylhexyl ester (0.3-0.8% by mass), 3-(methacryloyl)propyltrimethoxysilane (0.05-0.5% by mass), and vinyltriethoxysilane (0.05-0.2% by mass).

[0056] Among them, ethylene-vinyl acetate copolymer acts as a resin, octadecyl alcohol-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate acts as an antioxidant, sebacic acid bis(1,2,2,6,6-pentamethylpiperidinol) ester acts as a light stabilizer, triallyl isocyanurate, ethoxytrimethylolpropane tripropane triacrylate, carboperoxy acid-O,O-91,1-dimethylpropyl)-O-(2-ethylhexyl) ester and tert-butyl peroxycarbonate-2-ethylhexyl ester all act as crosslinking agents, and 3-(methacryloyl)propyltrimethoxysilane and vinyltriethoxysilane both act as coupling agents.

[0057] As another possible implementation, when the first adhesive film layer and / or the second adhesive film layer are POE adhesive film layers, the raw materials for preparing the POE adhesive film layer include: ethylene-butene copolymer with a mass percentage greater than or equal to 98%, octadecyl alcohol-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate with a mass percentage ranging from 0.03% to 0.1%, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate with a mass percentage ranging from 0.3% to 1%. The composition includes triallyl isocyanurate, carbonate-O,O-91,1-dimethylpropyl)-O-(2-ethylhexyl) ester (by mass), tert-butyl peroxycarbonate-2-ethylhexyl ester (by mass), vinyltrimethoxysilane (by mass), vinyltriethoxysilane (by mass), and triethoxypentylsilane (by mass).

[0058] Among them, the role of ethylene-butene copolymer is as a resin, the role of octadecyl alcohol-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is as an antioxidant, the role of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate is as a light stabilizer, the role of triallyl isocyanurate, carbonate-O,O-91,1-dimethylpropyl)-O-(2-ethylhexyl) ester and tert-butyl peroxycarbonate-2-ethylhexyl ester are all as crosslinking agents, and the role of vinyltrimethoxysilane and vinyltriethoxysilane are both as coupling agents.

[0059] Step S102: A hollow area is formed on the metal foil to obtain a grid-like metal foil; wherein the width of the border of the hollow area is greater than the gap between adjacent battery cells.

[0060] In this step, the metal foil is a pressed and flattened metal foil with a thickness ranging from 5μm to 150μm. If the metal foil is too thin, pinholes will be present, resulting in poor moisture barrier and water resistance. If the metal foil is too thick, the amount of metal foil used will increase, thus increasing manufacturing costs. For example, the thickness of the metal foil can be 5μm, 15μm, 25μm, 29μm, 35μm, 50μm, 80μm, 100μm, 101μm, 120μm, 150μm, etc.

[0061] Metal foils include, but are not limited to, any one of aluminum foil, copper foil, and tin foil. Aluminum foil, copper foil, and tin foil are easy to process.

[0062] The shape of the hollowed-out area can be the same as the shape of the battery cell, such as a rectangle or a square.

[0063] It should be noted that steps S101 and S102 can be interchanged, and this application does not impose any restrictions on this.

[0064] The edges of all the perforated areas form a grid, and the width of the edges of the perforated areas is greater than the gap between adjacent battery cells in order to ensure water resistance.

[0065] The width of the border around the hollowed-out area is not limited in this application and can be set according to the actual situation.

[0066] As one possible implementation, the width of the border around the hollowed-out area is not less than 2 mm. For example, the width of the border around the hollowed-out area can be 2 mm, 3 mm, 4 mm, 5 mm, 7 mm, etc.

[0067] For photovoltaic modules with non-small gaps, the frame width is preferably not less than 5mm. The purpose is to ensure that the mesh-like metal foil can effectively block the path of water vapor entering from the back of the photovoltaic module, thus preventing water vapor from corroding the cells.

[0068] In one embodiment of this application, forming a hollow area on a metal foil includes:

[0069] A perforated area is formed on a metal foil by stamping.

[0070] Metal foil is stamped using a fixed mold to form a grid-like metal foil sheet. The manufacturing process is simple and efficient.

[0071] A schematic diagram of the mesh-like metal foil 23 is shown below. Figure 3 As shown, when used in photovoltaic modules, each cutout area 231 corresponds to a solar cell, the cutout area 231 is smaller than or equal to the solar cell area, and the border 232 around the cutout area 231 is located at least in the gap area between adjacent solar cells.

[0072] Step S103: The first adhesive film layer, the mesh-shaped metal foil, and the second adhesive film layer are stacked sequentially and heated to melt the first adhesive film layer and the second adhesive film layer, forming a composite film layer of the first adhesive film layer, the mesh-shaped metal foil, and the second adhesive film layer, which serves as the back adhesive film.

[0073] In this step, when the first adhesive film layer, the mesh-like metal foil, and the second adhesive film layer are sequentially stacked and heated, the heating temperature range can be 75℃~150℃, for example, 75℃, 80℃, 90℃, 100℃, 120℃, 150℃, etc. The specific temperature range depends on the material of the adhesive film layer.

[0074] The first and second adhesive layers have a certain degree of adhesion. When heated and melted, the adhesion of the first and second adhesive layers is even better, resulting in better adhesion to the mesh-like metal foil. Furthermore, after the first and second adhesive layers are heated and melted, they become fluid, which binds more tightly to the mesh-like metal foil, achieving a seamless bond.

[0075] In this embodiment, a composite film layer formed by a first adhesive film layer, a mesh-like metal foil, and a second adhesive film layer is used as the back adhesive film. The width of the perimeter of the hollowed-out area in the mesh-like metal foil is greater than the gap between adjacent solar cells, resulting in near-zero water permeability. When moisture penetrates from the back of the photovoltaic module, it can prevent direct penetration of the solar cells, extending the moisture transport path within the back adhesive film and thus reducing or isolating moisture corrosion of the solar cells. The hollowed-out area in the mesh-like metal foil reduces the amount of metal foil used, lowering manufacturing costs. Furthermore, the composite of the first adhesive film layer, the mesh-like metal foil, and the second adhesive film layer is achieved through heating and melting, resulting in better adhesion between the first and second adhesive film layers and the mesh-like metal foil. This also allows the first and second adhesive film layers to become fluid, resulting in a tighter bond with the mesh-like metal foil and preventing gaps.

[0076] Based on the above embodiments, in one embodiment of this application, please refer to... Figure 4 The manufacturing methods for the back adhesive film include:

[0077] Step S201: Prepare the first adhesive film layer and the second adhesive film layer.

[0078] Step S202: Create a reflective structure on the surface of the metal foil.

[0079] The function of the reflective structure is to reflect the light passing between the cells and between the cell strings to the front glass substrate. After being refracted by the glass-air interface, part of the light is refracted to the surface of the cell and then reused, thereby improving the light utilization rate and thus increasing the power of the photovoltaic module.

[0080] As one possible implementation, a reflective structure can be formed on the surface of the metal foil by rolling. However, this embodiment does not specifically limit the method of forming the reflective structure. As another possible implementation, a stamping method can be used to form the reflective structure on the surface of the metal foil.

[0081] The method of producing reflective structures by rolling or stamping is simple and efficient.

[0082] The reflective structure protrudes from the surface of the metal foil. The portion of the reflective structure protruding from the surface of the metal foil can be trihedral, tetrahedral, hexahedral, octahedral, etc., and no specific limitation is made in this application.

[0083] Step S203: A hollow area is formed on the metal foil to obtain a grid-like metal foil; wherein the width of the border of the hollow area is greater than the gap between adjacent battery cells.

[0084] Step S204: The first adhesive film layer, the mesh-shaped metal foil, and the second adhesive film layer are stacked sequentially and heated to melt the first adhesive film layer and the second adhesive film layer, forming a composite film layer of the first adhesive film layer, the mesh-shaped metal foil, and the second adhesive film layer, which serves as the back adhesive film.

[0085] This application also provides a back adhesive film, which is prepared by the back adhesive film manufacturing method described in any of the above embodiments.

[0086] The back adhesive film includes a first adhesive film layer, a mesh-like metal foil, and a second adhesive film layer, which are stacked in sequence.

[0087] The first adhesive layer in the back adhesive film includes any one of POE adhesive layer, EVA adhesive layer, PVB adhesive layer, silicone adhesive layer, and composite adhesive layer; the second adhesive layer includes any one of POE adhesive layer, EVA adhesive layer, PVB adhesive layer, silicone adhesive layer, and composite adhesive layer.

[0088] The first adhesive layer and the second adhesive layer can be the same or different, and this application does not impose any restrictions.

[0089] When the back adhesive film in this application is used in photovoltaic modules, the moisture intrusion path is as follows: Figure 5 As shown, when water vapor invades from the back substrate 1, the water vapor's intrusion path becomes longer because the mesh-like metal foil 23 is impermeable to water. Since the water vapor's intrusion thickness is limited, it can reduce or isolate the corrosion of the solar cells by water vapor, thus achieving high-barrier encapsulation of single-glass photovoltaic modules.

[0090] This application also provides a photovoltaic module, which includes the back film described in any of the above embodiments.

[0091] A schematic diagram of a photovoltaic module is shown below. Figure 6 As shown, it includes a back substrate 1, a back adhesive film 2, a battery cell layer 3, a front adhesive film 4, and a front glass substrate 5 stacked in sequence. The back adhesive film 2 includes a first adhesive film layer 21, a mesh-like metal foil 23, and a second adhesive film layer 22.

[0092] The first adhesive film layer 21 can contact the back substrate 1, and the second adhesive film layer 22 can contact the battery cell layer 3; or the second adhesive film layer 22 can contact the back substrate 1, and the first adhesive film layer 21 can contact the battery cell layer 3.

[0093] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0094] The foregoing has provided a detailed description of the back adhesive film, its manufacturing method, and the photovoltaic module provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are merely for the purpose of helping to understand the solution and core ideas of this application. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the protection scope of this application.

Claims

1. A method for manufacturing a back adhesive film, characterized in that, include: Prepare the first and second adhesive film layers; A perforated area is formed on a metal foil to obtain a grid-like metal foil; wherein the width of the perimeter of the perforated area is greater than the gap between adjacent battery cells; The first adhesive film layer, the mesh-shaped metal foil, and the second adhesive film layer are stacked sequentially and heated to melt the first adhesive film layer and the second adhesive film layer, forming a composite film layer of the first adhesive film layer, the mesh-shaped metal foil, and the second adhesive film layer, which serves as the back adhesive film.

2. The method for manufacturing the back adhesive film as described in claim 1, characterized in that, Before forming a perforated area on the metal foil to obtain a grid-like metal foil, the process also includes: A reflective structure is fabricated on the surface of the metal foil.

3. The method for manufacturing the back adhesive film as described in claim 2, characterized in that, Fabricating a reflective structure on the surface of the metal foil includes: A reflective structure is formed on the surface of the metal foil by rolling or stamping.

4. The method for manufacturing the back adhesive film as described in claim 1, characterized in that, The width of the border around the hollowed-out area is not less than 2 millimeters.

5. The method for manufacturing the back adhesive film as described in claim 1, characterized in that, When the first adhesive film layer, the mesh-like metal foil, and the second adhesive film layer are stacked sequentially and heated, the heating temperature range is 75℃~150℃.

6. The method for manufacturing the back adhesive film as described in claim 1, characterized in that, Preparing the first and second adhesive film layers includes: The raw materials for preparing the first adhesive film layer and the second adhesive film layer are mixed evenly respectively; The first and second adhesive film layer raw materials, which are mixed evenly, are placed in a screw extruder to obtain the treated first adhesive film layer material and the treated second adhesive film layer material respectively. The treated first adhesive film layer material and the treated second adhesive film layer material are respectively placed in a casting machine to form the first adhesive film layer to be treated and the second adhesive film layer to be treated. The first adhesive film layer and the second adhesive film layer to be treated are cured respectively to obtain the first adhesive film layer and the second adhesive film layer.

7. The method for manufacturing the back adhesive film as described in claim 1, characterized in that, When the first adhesive film layer and / or the second adhesive film layer are EVA adhesive film layers, the raw materials for preparing the EVA adhesive film layer include: The composition includes, by weight, 98% or more of ethylene-vinyl acetate copolymer, 0.03-0.1% of octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 0.03-0.2% of bis(1,2,2,6,6-pentamethylpiperidinol) sebacate, 0.3-1% of triallyl isocyanurate, and 0.1-1% of ethoxytrimethylolpropionate. The mixture comprises: alkyltripropane triacrylate, carboperoxy acid (O,O-91,1-dimethylpropyl)-O-(2-ethylhexyl) ester (0.1-0.5% by mass), tert-butyl peroxycarbonate-2-ethylhexyl ester (0.3-0.8% by mass), 3-(methacryloyl)propyltrimethoxysilane (0.05-0.5% by mass), and vinyltriethoxysilane (0.05-0.2% by mass).

8. The method for manufacturing the back adhesive film as described in claim 1, characterized in that, When the first adhesive film layer and / or the second adhesive film layer are POE adhesive film layers, the raw materials for preparing the POE adhesive film layer include: ethylene-butene copolymer with a mass percentage greater than or equal to 98%, octadecyl alcohol-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate with a mass percentage ranging from 0.03% to 0.1%, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate with a mass percentage ranging from 0.03% to 0.3%, and triallyl isocyanate with a mass percentage ranging from 0.3% to 1%. The composition includes cyanurate, carbonate-O,O-91,1-dimethylpropyl)-O-(2-ethylhexyl) ester (mass percentage range of 0.02-0.8%), tert-butyl peroxycarbonate-2-ethylhexyl ester (mass percentage range of 0.3-0.8%), vinyltrimethoxysilane (mass percentage range of 0.01-0.2%), vinyltriethoxysilane (mass percentage range of 0.05-0.3%), and triethoxypentylsilane (mass percentage range of 0.1-0.4%).

9. The method for manufacturing the back adhesive film according to any one of claims 1 to 8, characterized in that, Forming perforated areas on metal foil includes: A perforated area is formed on a metal foil by stamping.

10. A backing adhesive film, characterized in that, The back adhesive film is prepared by the method for preparing the back adhesive film as described in any one of claims 1 to 9.

11. The back adhesive film as described in claim 10, characterized in that, The first adhesive layer in the back adhesive film includes any one of POE adhesive layer, EVA adhesive layer, PVB adhesive layer, silicone adhesive layer, and composite adhesive layer; the second adhesive layer includes any one of POE adhesive layer, EVA adhesive layer, PVB adhesive layer, silicone adhesive layer, and composite adhesive layer.

12. A photovoltaic module, characterized in that, The photovoltaic module includes the back film as described in any one of claims 10 to 11.

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