A method for manufacturing a gridless photovoltaic module and a gridless photovoltaic module

Abstract

The application discloses a preparation method of a main-grid-free photovoltaic module and the main-grid-free photovoltaic module, and relates to the technical field of photovoltaic module manufacturing. The specific implementation of the method comprises the following steps: point coating a first glue containing an oxygen-containing functional group on at least one side of a cell sheet; wherein the first glue forms a chemical bond with the cell sheet; arranging a solder strip corresponding to the point coating position of the first glue along a direction perpendicular to the fine grid of the cell sheet, and further point coating a second glue containing a hydroxyl functional group at the point coating position of the first glue, so that the first glue and the second glue containing the hydroxyl functional group jointly bond the solder strip to the cell sheet; wherein the second glue is connected with the first glue through intermolecular force or a chemical bond. The embodiment utilizes two glues containing different functional groups, and realizes the bonding between the solder strip and the cell sheet through the joint action of the two modes of chemical bonding and intermolecular force, thereby effectively improving the bonding effect of the solder strip and the cell sheet.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module manufacturing technology, and in particular to a method for preparing a gridless photovoltaic module and the gridless photovoltaic module itself. Background Technology

[0002] For gridless photovoltaic modules, adhesive is typically applied in dots to connect the solder ribbons to the grid on the solar cells. This adhesive is then used to bond the solder ribbons to the cells. Current dispensing methods primarily use a single type of adhesive. However, due to the different materials of the solder ribbons and solar cells, this method cannot simultaneously achieve a good bond with both the cells and the solder ribbons, only ensuring adhesion on one side. Therefore, existing dispensing methods suffer from insufficient adhesive strength. Summary of the Invention

[0003] In view of this, embodiments of the present invention provide a method for fabricating a grid-less photovoltaic module and a grid-less photovoltaic module. A first adhesive containing oxygen-containing functional groups achieves chemical bonding with the solar cell, while a second adhesive, containing hydroxyl functional groups, achieves better bonding with the first adhesive through hydrogen bonds or chemical bonds formed between the oxygen-containing functional groups. That is, embodiments of the present invention utilize two adhesives containing different functional groups, achieving bonding between the solder ribbon and the solar cell through the combined action of chemical bonding and intermolecular forces, effectively improving the bonding effect between the solder ribbon and the solar cell.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0005] In a first aspect, the present invention provides a method for preparing a gridless photovoltaic module, comprising: step 1, applying a first adhesive containing oxygen-containing functional groups to at least one side of a solar cell; wherein the first adhesive forms a chemical bond with the solar cell;

[0006] Step 2: Arrange the solder ribbons along the direction perpendicular to the grid of the battery cell, corresponding to the dotting positions of the first adhesive, and further dot the first adhesive positions with a second adhesive containing hydroxyl functional groups. The first adhesive and the second adhesive containing hydroxyl functional groups together bond the solder ribbons to the battery cell; wherein, the second adhesive 3 is bonded to the first adhesive and the solder ribbons respectively through intermolecular forces.

[0007] Optionally, after step 1 and before step 2, the method further includes: curing the first adhesive; step 2 includes: applying a second adhesive on top of the cured first adhesive; and curing the second adhesive after completely embedding the solder ribbon into the second adhesive.

[0008] Optionally, the coating thickness of the first adhesive does not exceed the height of the fine grid.

[0009] Optionally, step 2 includes: embedding the solder ribbon portion into the first adhesive and then curing the first adhesive; applying the second adhesive in layers at the application locations of the first adhesive so that the second adhesive covers the unembedded portion of the solder ribbon; and then curing the second adhesive.

[0010] Optionally, the thickness of the first adhesive is greater than half the thickness of the solder strip, but less than the thickness of the solder strip.

[0011] Optionally, the first adhesive comprises any one or more of the following materials: polyurethane acrylic oligomer, isocyanate prepolymer UV-curable adhesive, phenolic resin, and polyetheretherketone derivative adhesive.

[0012] Optionally, when the first adhesive is a polyurethane acrylic oligomer, the second adhesive is an epoxy acrylic oligomer; hydrogen bonds are formed by the reaction of the hydroxyl groups contained in the epoxy acrylic oligomer with the ketone groups and isocyanate groups in the polyurethane acrylic oligomer, so that the second adhesive and the first adhesive are bonded together by intermolecular forces.

[0013] Optionally, the surface of the battery cell is a transparent conductive film doped with tin.

[0014] Optionally, when the first adhesive is an isocyanate prepolymer photocurable adhesive modified with polytetrahydrofuran ether diol, and the second adhesive is an epoxy acrylic oligomer;

[0015] The second adhesive and the first adhesive are bonded together by the chemical bonds formed by the cross-linking of the hydroxyl groups contained in the epoxy acrylic oligomer and the isocyanate groups in the isocyanate prepolymer photocurable adhesive.

[0016] Optionally, the method further includes: step 3, arranging multiple solar cells in series to form a solar cell string using the solder ribbon; step 4, stacking and laminating the solar cell string with a cover plate, an encapsulating film, and a backplate to form the gridless photovoltaic module.

[0017] Secondly, the present invention provides a gridless photovoltaic module prepared by the above-described preparation method, comprising: a solar cell, a first adhesive containing oxygen-containing functional groups and a second adhesive containing hydroxyl-containing functional groups coated on at least one side of the solar cell, and solder ribbons arranged perpendicular to the grid direction of the solar cell; the first adhesive is located between the second adhesive and the solar cell; the first adhesive forms a chemical bond with the solar cell; the first adhesive and the second adhesive together bond the solder ribbons to the solar cell, wherein the second adhesive is bonded to the first adhesive and the solder ribbons respectively by intermolecular forces.

[0018] The first aspect of the above-mentioned invention has the following advantages or beneficial effects: The first adhesive containing oxygen-containing functional groups can achieve chemical bonding with the battery cell; the hydrogen bonds or chemical bonds formed between the first and second adhesives can achieve better bonding. That is, the embodiments of the present invention utilize two adhesives containing different functional groups, achieving bonding between the solder ribbon and the battery cell through the combined action of chemical bonding and intermolecular forces, effectively improving the bonding effect between the solder ribbon and the battery cell. Attached Figure Description

[0019] The accompanying drawings are provided to better understand the invention and are not intended to unduly limit the scope of the invention. Wherein:

[0020] Figure 1 This is a schematic flowchart of a method for manufacturing a gridless photovoltaic module according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic flowchart of a preparation method for step S102 according to an embodiment of the present invention;

[0022] Figure 3 This is a cross-sectional schematic diagram of the positional relationship between the solder strip and the battery cell according to an embodiment of the present invention;

[0023] Figure 4 This is an overall structure of a gridless photovoltaic module provided according to an embodiment of the present invention;

[0024] Figure 5 This is a schematic flowchart of another preparation method for step S102 according to an embodiment of the present invention;

[0025] Figure 6 This is a cross-sectional schematic diagram of another positional relationship between the solder strip and the battery cell provided by an embodiment of the present invention;

[0026] Figure 7 This is another overall structure of a gridless photovoltaic module provided according to an embodiment of the present invention;

[0027] Figure 8 This is a schematic flowchart of a method for preparing a gridless photovoltaic module according to an embodiment of the present invention.

[0028] The attached figures are labeled as follows:

[0029] 1-Battery cell; 2-First adhesive; 3-Second adhesive; 4-Solder strip. Detailed Implementation

[0030] A solar cell is a thin-film photovoltaic semiconductor that directly generates electricity using sunlight. Also known as a "solar chip" or "photovoltaic cell," it can instantly output voltage and generate current when a circuit is established, provided it receives sufficient illumination. In physics, this is called solar photovoltaic (PV). To facilitate and clearly describe the fabrication method and the solar cell of this invention, exemplary embodiments of the invention are described below with reference to the accompanying drawings. These embodiments include various details to aid understanding and should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0031] Existing dispensing methods primarily use light-curing adhesives, which are cured by irradiating with ultraviolet light to change the adhesive's form. However, this dispensing method, after adhesive modification, cannot simultaneously achieve strong adhesion to both the battery cell 1 and the solder ribbon 4. Therefore, this embodiment of the invention improves the dispensing method to achieve bonding effects between the solder ribbon 4 and the battery cell 1 using two different adhesives.

[0032] In one embodiment of the present invention, such as Figure 1 As shown, this embodiment provides a method for fabricating a busbar-less photovoltaic module, which may include the following steps:

[0033] Step S101: Apply a first adhesive 2 containing oxygen-containing functional groups to at least one side of the battery cell 1; wherein the first adhesive 2 forms a chemical bond with the battery cell 1.

[0034] In step S102, solder ribbon 4 is arranged along the direction perpendicular to the grid of the battery cell 1, corresponding to the dotting position of the first adhesive 2, and a second adhesive 3 containing hydroxyl functional groups is further dotted at the dotting position of the first adhesive 2. The first adhesive 2 and the second adhesive 3 containing hydroxyl functional groups together bond the solder ribbon 4 to the battery cell 1; wherein, the second adhesive 3 is bonded to the first adhesive 1 through intermolecular forces or chemical bonds.

[0035] When solder ribbons need to be bonded to both sides of the battery cell 1, the first adhesive 2 and the second adhesive 3 can be applied to both sides of the battery cell 1. This invention does not impose specific limitations on this, and the application of adhesives can be based on the actual situation. As for the location of the first adhesive 2 in step S102, it is preferable to apply it in parallel on each fine grid, so that the solder ribbon 4 can be fixedly connected to each perpendicular fine grid, ensuring the bonding effect between the solder ribbon and the fine grid.

[0036] It is understandable that, in order to ensure that a chemical bond can be formed between the first adhesive 2 and the battery cell 1, the type of adhesive is usually matched with the material of the battery cell 1, that is, the two can form chemical bonds to form a chemical bond. Therefore, in an optional embodiment, the battery cell 1 in this embodiment of the invention is a transparent conductive film doped with tin, preferably a transparent conductive film with tin doped on its surface.

[0037] In this embodiment of the invention, by adding tin (Sn) to the battery cell 1, tin can replace the indium (In) element in the original indium trioxide (In2O3) lattice of the battery cell 1. This replaces the trivalent In element in the original In2O3 with the tetravalent Sn element in SnO2, contributing an electron to the conduction band, thereby forming an oxygen hole on the battery cell 1. The oxygen hole can adsorb oxygen-containing functional groups. Compared to the prior art that only utilizes intermolecular forces to bond the adhesive to the battery cell 1, this embodiment of the invention utilizes the adsorption of oxygen-containing functional groups by oxygen holes, resulting in stronger adhesion and a better bonding effect.

[0038] For the first adhesive 2 containing oxygen-containing functional groups, in an optional embodiment, the first adhesive 2 may include any one or more of the following materials: polyurethane acrylic oligomer, isocyanate prepolymer UV-curable adhesive, phenolic resin, and polyetheretherketone derivative adhesives. The interaction mode between the first adhesive 2 and the second adhesive 3 will differ depending on the material. In an optional embodiment, when the first adhesive 2 is a polyurethane acrylic oligomer, the second adhesive 3 is an epoxy acrylic oligomer. Hydrogen bonds are formed by the reaction of the hydroxyl groups in the epoxy acrylic oligomer with the ketone and isocyanate groups in the polyurethane acrylic oligomer, allowing the second adhesive 3 and the first adhesive 2 to be bonded together through intermolecular forces. Hydrogen bonds are a type of intermolecular force; the more hydrogen bonds present, the better the adhesive performance between the first adhesive 2 and the second adhesive 3. It is understood that the intermolecular forces formed between the first adhesive 2 and the second adhesive 3, compared to the van der Waals forces generated after adhesive curing in the prior art, can significantly improve the adhesive strength and ensure the bonding effect. In another optional embodiment, when the first adhesive 2 is an isocyanate prepolymer photocurable adhesive modified with polytetrahydrofuran ether diol, and the second adhesive 3 is an epoxy acrylic oligomer, chemical bonds are formed by the reaction of the hydroxyl groups contained in the epoxy acrylic oligomer with the isocyanate groups in the isocyanate prepolymer photocurable adhesive, thus bonding the second adhesive 3 and the first adhesive 2 together through chemical bonds. Compared with intermolecular forces, the interaction provided by chemical bonds is stronger. Therefore, the interaction force between the first adhesive 2 and the second adhesive 3 provided by the present invention is superior to the van der Waals forces used for bonding in the prior art, which can greatly improve the bonding performance. In a preferred embodiment, the second adhesive 2 can be a flexible epoxy acrylic oligomer. Compared with non-flexible ordinary epoxy acrylic oligomers, flexible epoxy acrylic oligomers have more hydroxyl groups, which can crosslink with isocyanate groups to form more chemical bonds, resulting in stronger adhesion and better bonding effect between the first adhesive 1 and the second adhesive 2.

[0039] The bonding between the second adhesive 3 and the solder ribbon 4 follows the same principle as existing physical bonding, utilizing intermolecular forces. Therefore, this invention will not elaborate further. It is evident that in this embodiment, by applying the first adhesive 2 containing oxygen-containing functional groups, good adhesion between the first adhesive 2 and the battery cell 1 can be ensured through chemical bonding. Furthermore, by applying the second adhesive 3 containing hydroxyl functional groups at the same application sites as the first adhesive 2, strong intermolecular forces are simultaneously maintained between the first adhesive 2 and the solder ribbon 4, ensuring both adhesion between the second adhesive 2 and the second adhesive 3. In other words, the solder ribbon 4 is bonded to the battery cell 1 under the combined action of the first adhesive 2 and the second adhesive 3.

[0040] Regarding the specific bonding process, embodiments of the present invention provide two different bonding methods to ultimately achieve different bonding structures. One method involves embedding the solder ribbon 4 only in the second adhesive 3, achieving bonding with the solder ribbon 4 through the second adhesive 3. The other method involves embedding the solder ribbon 4 in both the first adhesive 2 and the second adhesive 3, achieving bonding with the solder ribbon 4 through the combined action of the two adhesives. The following is a detailed description of these two different bonding structures:

[0041] (I) In an optional embodiment, after step S101 and before step S102, the method further includes: curing the first adhesive 2; after curing, step S102 can be performed as follows: Figure 2 As shown, it includes:

[0042] Step S201: Apply the second adhesive 3 in spots on the cured first adhesive 2;

[0043] Step S202: After the solder ribbon 4 is fully embedded in the second adhesive 3, the second adhesive 3 is cured.

[0044] The curing methods for the first adhesive 2 and the second adhesive 3 can be either ultraviolet light irradiation (UV irradiation) or natural curing; this invention does not limit the curing methods.

[0045] Through the above process, we can obtain the following: Figure 3 The cross-sectional schematic diagram showing the positional relationship between the solder strip 4 and the battery cell 1, and as shown below... Figure 4 The diagram shows the overall structure of a gridless photovoltaic module. Among them, from... Figure 3 and Figure 4 As can be seen, since the first adhesive 2 was cured before step S102, there is a clear boundary between the second adhesive 3 and the first adhesive 2, and the solder ribbon 4 can only be embedded in the second adhesive 3. The second adhesive 3 completely wraps the solder ribbon 4 to ensure the bonding effect between the solder ribbon 4 and the second adhesive 3.

[0046] In this bonding method, to minimize the amount of the first adhesive 2 and the second adhesive 3 applied while ensuring bonding effectiveness, in one optional embodiment, the coating thickness of the first adhesive 2 does not exceed the height of the fine grid. It is understood that, given the same contact area, excessive thickness can negatively impact the bonding performance between the first adhesive 2 and the battery cell 1, while insufficient thickness may result in gaps between the first adhesive 2 and the battery cell 1 during application, preventing the formation of sufficient chemical bonds to ensure effective bonding.

[0047] (ii) In another optional embodiment, step S102 can be as follows: Figure 5 As shown, it includes:

[0048] Step S501: After embedding the solder ribbon 4 into the first adhesive 2, cure the first adhesive 2;

[0049] Step S502: At the dotting position of the first adhesive 2, apply the second adhesive 3 in layers to cover the unembedded part of the solder ribbon 4 with the second adhesive 3.

[0050] Step S503: Curing the second adhesive 3.

[0051] Through the above process, we can obtain the following: Figure 6 The cross-sectional schematic diagram showing the positional relationship between the solder strip 4 and the battery cell 1, and as shown below... Figure 7 The overall structure of the photovoltaic module is shown. Among them, from... Figure 6 and Figure 7 As can be seen, since the first adhesive 2 has not yet cured when the solder ribbon 4 is placed, a portion of the solder ribbon 4 will be embedded inside the first adhesive 2. Then, by applying the second adhesive 3 in layers at the application points of the first adhesive 2, the portion of the solder ribbon 4 that is not embedded in the first adhesive 2 can be wrapped with the second adhesive 3. Thus, after the second adhesive 3 cures, the bonding effect of the solder ribbon 4 is guaranteed.

[0052] It should be noted that since the first adhesive 2 only forms a chemical bond with the battery cell 1 and does not bond with the solder ribbon 4, it is not advisable to completely embed the solder ribbon 4 into the first adhesive 2. Instead, the second adhesive 2 is needed to ensure a strong bond between the solder ribbon 4 and the first adhesive 2. Therefore, in this bonding method, in an optional embodiment, the thickness of the first adhesive 2 is greater than half the thickness of the solder ribbon 4 but less than the thickness of the solder ribbon 4. That is, by controlling the coating thickness of the first adhesive 2, the situation where the solder ribbon 4 is completely embedded in the first adhesive 3 is avoided.

[0053] pass Figures 2 to 7 As can be seen, the embodiments of the present invention achieve the technical effect of firmly bonding the solder ribbon 4 to the battery cell 1 by forming two different methods, namely chemical bonds and intermolecular forces, and by using two layers of adhesive to connect the battery cell 1 and the solder ribbon 4 respectively.

[0054] In an optional embodiment of the present invention, after step S102, as follows: Figure 8 As shown, it also includes:

[0055] Step S801: Multiple battery cells 1 are connected in series to form a battery string using solder ribbons 4;

[0056] In step S802, the battery string is stacked with the cover plate, encapsulating film and back sheet, and then laminated to form a gridless photovoltaic module.

[0057] The present invention does not specifically limit the number of battery cells 1, but it must ensure that the solder ribbon 4 and the fine grids on multiple battery cells 1 are all vertically arranged, so as to achieve the purpose of connecting multiple battery cells 1 in series to form a battery string using the solder ribbon 4. As for the number of solder ribbons 4, there can be one or more, preferably multiple solder ribbons 4 arranged in parallel to ensure the current conduction effect.

[0058] In summary, the method for fabricating a gridless photovoltaic module provided by this invention utilizes a first adhesive containing oxygen-containing functional groups to achieve chemical bonding with the solar cell, and a second adhesive containing hydroxyl-containing functional groups to achieve physical bonding with both the first adhesive and the solder ribbon. In other words, this invention utilizes two adhesives containing different functional groups to achieve bonding between the solder ribbon and the solar cell through the combined action of chemical bonding and intermolecular forces, effectively improving the bonding effect between the solder ribbon and the solar cell.

[0059] Figure 4 and Figure 7 A cross-sectional structural schematic diagram of a gridless photovoltaic module provided in an embodiment of the present invention is shown, as follows: Figure 4 and Figure 7 As shown, the gridless photovoltaic module provided by the present invention includes: a solar cell 1, a first adhesive 2 containing oxygen-containing functional groups and a second adhesive 3 containing hydroxyl functional groups coated on at least one side of the solar cell 1, and a solder ribbon 4 arranged perpendicular to the grid direction of the solar cell 1; the first adhesive 2 is located between the second adhesive 3 and the solar cell 1; the first adhesive 2 forms a chemical bond with the solar cell 1; the first adhesive 2 and the second adhesive 3 together bond the solder ribbon 4 to the solar cell 1, wherein the second adhesive 3 is bonded to the first adhesive 1 and the solder ribbon 4 respectively through intermolecular forces.

[0060] Based on the different sequences of curing of the first adhesive 2 and the second adhesive 3 and the placement of the solder ribbon 4, the following can be obtained: Figure 4 and Figure 7 Two different gridless photovoltaic modules with different structures. Specifically, after first curing the first adhesive 2, placing the solder ribbon 4 into the second adhesive 3 and curing it, the following can be obtained: Figure 4 The gridless photovoltaic module shown has solder ribbon 4 positioned above the first adhesive 2 and completely embedded inside the second adhesive 3. When the first adhesive 2 is applied and solder ribbon 4 is placed in before curing, and the second adhesive 3 is applied in layers after curing, the gridless photovoltaic module shown in Figure 7 will have part of solder ribbon 4 embedded inside the first adhesive 2, while the other part will be wrapped by the second adhesive 3. That is, the first adhesive 2 and the second adhesive 3 work together to bond the solder ribbon 4.

[0061] In summary, the gridless photovoltaic module provided by this invention achieves chemical bonding between the first adhesive containing oxygen-containing functional groups and the solar cell. Furthermore, the hydrogen bonds or chemical bonds formed between the second adhesive and the first adhesive through the presence of hydroxyl functional groups and oxygen-containing functional groups provide a better bond. In other words, this invention utilizes two adhesives containing different functional groups, achieving bonding between the solder ribbon and the solar cell through the combined action of chemical bonding and intermolecular forces, effectively improving the bonding effect between the solder ribbon and the solar cell.

[0062] Example 1

[0063] S1. Apply polyurethane acrylic oligomer to the surface of the battery cell, with a thickness not exceeding the height of the fine grid, and cure it by irradiation with ultraviolet light.

[0064] S2. Apply epoxy acrylic oligomer to the surface of the cured polyurethane acrylate oligomer in a dotted manner, and embed multiple solder strips arranged at intervals perpendicular to the fine grid direction into the polyurethane acrylate.

[0065] S3. The epoxy acrylic oligomer is cured by irradiation with ultraviolet light, at which point the solder ribbon is cured inside the epoxy acrylic oligomer.

[0066] By repeatedly executing S1 to S3, a battery string formed by connecting multiple battery cells in series is obtained.

[0067] S4. Connect multiple battery strings in series or parallel according to the circuit design to form a battery cell layer;

[0068] S5. The battery cell layer is stacked with the cover plate, encapsulating film and back sheet, and then laminated and encapsulated into a gridless photovoltaic module.

[0069] S6. Frame the gridless photovoltaic modules and perform appearance testing, EL testing (electroluminescence testing), IV testing (current-voltage alert testing), and DH experiment.

[0070] The test results are as follows: the appearance of the busbarless photovoltaic module is not obviously abnormal and meets the module appearance and performance testing standards; no bending or displacement of the solder strips after lamination was observed, and there were no poor solder joints in the EL, which greatly improved the yield of the busbarless module; the peel force between the solder strip and the cell tested during the manufacturing process was above 1N, which meets the reliability requirements; at the same time, the manufactured module meets the requirements of 2000 cycles of dynamic load and 5400 / 2400MPa of static load, and the power loss is 2.73% after 1000h of damp heat test.

[0071] Example 2

[0072] S1. Apply polyurethane acrylic oligomer to the surface of the battery cell, and embed multiple solder ribbons arranged at intervals perpendicular to the grid direction into the polyurethane acrylic oligomer, and cure it by irradiation with ultraviolet light; wherein, the thickness of the polyurethane acrylic oligomer is greater than half the thickness of the solder ribbon and less than the thickness of the solder ribbon.

[0073] S2. Apply epoxy acrylic oligomer to the corresponding positions of the solder ribbon partially embedded with polyurethane acrylic oligomer, and cure the epoxy acrylic oligomer by irradiation with ultraviolet light.

[0074] By repeatedly executing S1 to S2, a battery string formed by connecting multiple battery cells in series is obtained.

[0075] S3. Connect multiple battery strings in series or parallel according to the circuit design to form a battery cell layer;

[0076] S4. The battery cell layer is stacked with the cover plate, encapsulating film and back sheet, and then laminated and encapsulated into a gridless photovoltaic module.

[0077] S5. Frame the gridless photovoltaic modules and perform appearance testing, EL testing (electroluminescence testing), IV testing (current-voltage alert testing), and DH experiment.

[0078] The test results are as follows: the appearance of the busbarless photovoltaic module is not obviously abnormal and meets the module appearance and performance testing standards; no bending or displacement of the solder strip after lamination was observed, and there were no poor solder joints in the EL, which greatly improved the yield of the busbarless module; the peel force between the solder strip and the cell tested during the manufacturing process was above 1.3N, which meets the reliability requirements; at the same time, the manufactured module meets the requirements of 2000 cycles of dynamic load and 5400 / 2400MPa of static load, and the power loss is 2.51% after 1000h of damp heat test.

[0079] Example 3

[0080] S1. Apply HDI prepolymer photocurable adhesive modified with polytetrahydrofuran ether diol to the surface of the battery cell, and embed multiple solder ribbons arranged at intervals perpendicular to the grid direction into the HDI prepolymer photocurable adhesive, and cure it by irradiation with ultraviolet light; wherein, the thickness of the HDI prepolymer photocurable adhesive is greater than half the thickness of the solder ribbon and less than the thickness of the solder ribbon.

[0081] S2. Apply flexible epoxy acrylic oligomer to the corresponding position of the solder ribbon partially embedded with HDI prepolymer UV-curable adhesive, and cure the flexible epoxy acrylic oligomer by irradiation with ultraviolet light.

[0082] By repeatedly executing S1 to S2, a battery string formed by connecting multiple battery cells in series is obtained.

[0083] S3. Connect multiple battery strings in series or parallel according to the circuit design to form a battery cell layer;

[0084] S4. The battery cell layer is stacked with the cover plate, encapsulating film and back sheet, and then laminated and encapsulated into a gridless photovoltaic module.

[0085] S5. Frame the gridless photovoltaic modules and perform appearance testing, EL testing (electroluminescence testing), IV testing (current-voltage alert testing), and DH experiment.

[0086] The test results are as follows: the appearance of the busbarless photovoltaic module is not obviously abnormal and meets the module appearance and performance testing standards; no bending or displacement of the solder strips after lamination was observed, and there were no poor solder joints in the EL, which greatly improved the yield of the busbarless module; the peel force between the solder strip and the cell tested during the manufacturing process was above 1.1N, which meets the reliability requirements; at the same time, the manufactured module meets the requirements of 2000 cycles of dynamic load and 5400 / 2400MPa of static load, and the power loss is 3.11% after 1000h of damp heat test.

[0087] Comparative Example 1

[0088] S1. Apply a 230μm thick polyurethane acrylic oligomer to the surface of the battery cell.

[0089] S2. Multiple solder strips arranged at intervals perpendicular to the direction of the fine grid are embedded in polyurethane acrylic oligomer and cured by irradiation with ultraviolet light.

[0090] By repeatedly executing S1 to S2, a battery string formed by connecting multiple battery cells in series is obtained.

[0091] S3. Connect multiple battery strings in series or parallel according to the circuit design to form a battery cell layer;

[0092] S4. The battery cell layer is stacked with the cover plate, encapsulating film and back sheet, and then laminated and encapsulated into a gridless photovoltaic module.

[0093] S5. Frame the gridless photovoltaic modules and perform EL testing.

[0094] The test results are as follows: In terms of appearance, some solder strips of the gridless photovoltaic module were found to be misaligned. The peel force between the solder strip and the cell detected during the manufacturing process was about 0.1-0.15N, and some points could reach about 0.6N, which does not meet the reliability requirements. In addition, multiple serious cold solder joints were found in the EL.

[0095] The above steps are provided only to help understand the structure, method, and core ideas of this invention. Those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. A method for fabricating a gridless photovoltaic module, characterized in that, include: Step 1: Apply a first adhesive (2) containing oxygen-containing functional groups to at least one side of the battery cell (1); wherein the surface of the battery cell (1) is a transparent conductive film doped with tin, and the first adhesive (2) forms a chemical bond with the battery cell (1). Step 2: Arrange the solder ribbon (4) along the direction perpendicular to the grid of the battery cell (1) corresponding to the dotting position of the first adhesive (2), and further dot the second adhesive (3) containing hydroxyl functional groups at the dotting position of the first adhesive (2). The first adhesive (2) and the second adhesive (3) containing hydroxyl functional groups together bond the solder ribbon (4) to the battery cell (1); wherein, the second adhesive (3) is bonded to the first adhesive (2) through intermolecular forces or chemical bonds.

2. The preparation method according to claim 1, characterized in that, After step 1 and before step 2, the process further includes: curing the first adhesive (2); Step 2 includes: Apply the second adhesive (3) in dots onto the cured first adhesive (2); After the solder ribbon (4) is fully embedded in the second adhesive (3), the second adhesive (3) is cured.

3. The preparation method according to claim 2, characterized in that, The coating thickness of the first adhesive (2) does not exceed the height of the fine grid.

4. The preparation method according to claim 1, characterized in that, Step 2 includes: After embedding the solder strip (4) into the first adhesive (2), the first adhesive (2) is cured. At the dotting location of the first adhesive (2), the second adhesive (3) is dotted in layers so that the second adhesive (3) covers the unembedded portion of the solder ribbon (4); The second adhesive (3) is cured.

5. The preparation method according to claim 4, characterized in that, The thickness of the first adhesive (2) is greater than half the thickness of the solder strip (4) but less than the thickness of the solder strip (4).

6. The preparation method according to any one of claims 1 to 5, characterized in that, The first adhesive (2) includes any one or more of the following materials: polyurethane acrylic oligomer, isocyanate prepolymer light-curing adhesive, phenolic resin, and polyether ether ketone derivative adhesive.

7. The preparation method according to claim 6, characterized in that, When the first adhesive (2) is a polyurethane acrylic oligomer and the second adhesive (3) is an epoxy acrylic oligomer; Hydrogen bonds are formed by the reaction of the hydroxyl groups contained in the epoxy acrylic oligomer with the ketone and isocyanate groups in the polyurethane acrylic oligomer, so that the second adhesive (3) and the first adhesive (2) are bonded together by intermolecular forces.

8. The preparation method according to claim 6, characterized in that, When the first adhesive (2) is an isocyanate prepolymer photocurable adhesive modified with polytetrahydrofuran ether diol, and the second adhesive (3) is an epoxy acrylic oligomer; The second adhesive (3) and the first adhesive (2) are bonded together by the chemical bonds formed by the reaction of the hydroxyl groups contained in the epoxy acrylic oligomer with the isocyanate groups in the isocyanate prepolymer photocurable adhesive.

9. The preparation method according to claim 1, characterized in that, Also includes: Step 3: Connect multiple battery cells (1) in series to form a battery string using the solder strip (4); Step 4: Stack the battery string with the cover plate, encapsulating film and back sheet, and laminate them to form the gridless photovoltaic module.

10. A gridless photovoltaic module prepared by any one of claims 1 to 9, characterized in that, include: The battery cell (1) has a first adhesive (2) containing oxygen-containing functional groups and a second adhesive (3) containing hydroxyl functional groups applied to at least one side of the battery cell (1), and solder strips (4) arranged perpendicular to the grid direction of the battery cell (1). The first adhesive (2) is located between the second adhesive (3) and the battery cell (1); The first adhesive (2) forms a chemical bond with the battery cell (1); The first adhesive (2) and the second adhesive (3) together bond the solder ribbon (4) to the battery cell (1), wherein the second adhesive (3) is bonded to the first adhesive (2) through intermolecular forces or chemical bonds.

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