Main-grid-free conductive fixing glue and preparation method of main-grid-free photovoltaic module

Abstract

The invention relates to the technical field of main-grid-free photovoltaic modules, in particular to main-grid-free conductive fixing glue and a preparation method of the main-grid-free photovoltaic module, and the main-grid-free conductive fixing glue comprises the following components in percentage by weight: 21%-78% of fixing glue, 10%-40% of conductive powder and 10%-40% of low-temperature soldering tin particles; wherein the melting point of the low-temperature soldering tin particles is 90-145 DEG C, and all the components are mixed to form the main-grid-free conductive fixing glue. According to the main-grid-free photovoltaic module, the main-grid-free conductive fixing glue is used for connecting an interconnection strip and a photovoltaic battery piece. The invention has the following beneficial effects: 1, good conductivity between the laminated interconnection strip and the battery grid line can be ensured without using a skin film, and the production cost is reduced; and 2, after a subsequent thermal cycle test of the assembly, pseudo soldering is not generated, no black spot exists in an EL image, and the power attenuation of the assembly is reduced.

Description

Technical Field

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

[0002] Busbarless (OBB) technology eliminates the traditional main grid on photovoltaic (PV) cells, employing innovative wire bonding schemes or other current-conducting mechanisms to achieve current conduction during PV module integration. The core of this technology lies in using a fixing adhesive to replace traditional welding processes, achieving mechanical fixation between the welding wire and the fine grid of the PV cell, followed by lamination to achieve electrical connection. With the PV industry's increasing demand for cost reduction and efficiency improvement, OBB technology and its supporting fixing adhesives have become a hot research topic in the industry.

[0003] Existing gridless fixing adhesives cure via UV or thermosetting to fix the welding wires and photovoltaic cells. However, the cured adhesive does not melt during lamination. After lamination, some adhesive remains between the welding wire and the photovoltaic cell, preventing proper alloying and fixing of the welding wire and grid lines. This results in black dots appearing as adhesive spots on the module's EL image. Figure 3 As shown, existing gridless fixing adhesives all require a highly cross-linked skin film to ensure the connection between the welding wire and the photovoltaic cell, and to avoid poor soldering. Summary of the Invention

[0004] The technical problem to be solved by this invention is that gridless photovoltaic modules using gridless fixing adhesive are prone to producing EL black spots at the adhesive points.

[0005] The technical solution adopted by this invention to solve its technical problem is: a main grid-free conductive fixing adhesive, comprising the following components by weight percentage:

[0006] Fixative adhesive 21%–78%

[0007] Conductive powder 10%–40%

[0008] Low-temperature solder particles: 10%–40%;

[0009] The low-temperature solder particles have a melting point of 90℃~145℃, and the components are mixed to form a gridless conductive fixing adhesive.

[0010] In some embodiments, the fixing adhesive may optionally include the following components, each component comprising a weight percentage in the gateless conductive fixing adhesive:

[0011] Epoxy resin 20%–70%

[0012] Hot acid initiator 0.5%–3%

[0013] Thixotropic agent 0.5%–5%.

[0014] In some embodiments, the fixing adhesive may be a low-temperature molten adhesive that softens and flows at the lamination temperature of the photovoltaic module.

[0015] In some embodiments, the fixing adhesive may be a type of adhesive that can melt at low temperatures after curing, and which softens and flows at 105°C to 120°C.

[0016] In some embodiments, the fixing adhesive may optionally include the following components, each component comprising a weight percentage in the gateless conductive fixing adhesive:

[0017] Low-temperature resin 10%–30%

[0018] Epoxy resin 10%–40%

[0019] Hot acid initiator 0.5%–3%

[0020] Thixotropic agent 0.5%–5%;

[0021] The cured low-temperature resin softens and flows at 105℃~120℃. The low-temperature resin is an epoxy-acrylic graft copolymer resin.

[0022] In some embodiments, the conductive powder may be one or more of nano-iron powder, aluminum powder, conductive graphite, and copper powder.

[0023] The low-temperature solder particles are tin-bismuth alloy powder.

[0024] In some embodiments, the epoxy resin may be one or more selected from bisphenol A type epoxy resin, alicyclic epoxy resin, phenolic epoxy resin, and oxetane.

[0025] In some embodiments, the thermal acid initiator may optionally be one or more of hexafluoroantimonate, aromatic sulfonate, and phosphonium salt;

[0026] The thixotropic agent is one or more of fumed silica, organobentonite, and polyamide wax.

[0027] In some embodiments, the optional method for preparing the low-temperature resin includes the following steps:

[0028] (1) Under an inert atmosphere, the epoxy resin solution is heated to 108℃~112℃, and then the monomer premix is ​​added dropwise at a uniform rate. After the addition is complete, the reaction is kept at 110℃~115℃ for 2~3 hours to allow the monomer to fully polymerize.

[0029] (2) Add a catalyst to the system obtained in step (1) and monitor the reaction progress by periodically measuring the acid value of the reaction system;

[0030] (3) After the reaction stops, remove the organic solvent to obtain epoxy-acrylic grafted resin;

[0031] Among them, the epoxy resin solution is a solution formed by dissolving epoxy resin in an organic solvent;

[0032] The monomer premix is ​​a mixture of methyl methacrylate, butyl acrylate, acrylic acid, BPO initiator and organic solvent.

[0033] The weight ratio of monomer premix to epoxy resin solution is 10:7 to 10:9. The weight percentage of each component in the monomer premix is ​​as follows: methyl methacrylate 24.5%, butyl acrylate 24.5%, acrylic acid 36%, BPO initiator 2%, xylene 6%, and ethyl acetate 7%.

[0034] A method for manufacturing a gridless photovoltaic module involves using the aforementioned gridless conductive adhesive to connect interconnect strips to photovoltaic cells, wherein the gridless conductive adhesive covers the overlapping area between the interconnect strips and the grid lines of the photovoltaic cells.

[0035] In some embodiments, optionally, the interconnecting strip is connected to the photovoltaic cell by a strip-shaped, gridless conductive adhesive extending along the length of the interconnecting strip.

[0036] The beneficial effects of this invention are: 1. It can ensure good conductivity between the interconnect strips and battery grid lines after lamination without using a skin membrane, thereby reducing production costs.

[0037] 2. After subsequent thermal cycling tests, the components did not exhibit any cold solder joints, there were no black spots in the EL diagram, and the component power degradation was reduced. Attached Figure Description

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0039] Figure 1 This is a schematic diagram of the series connection process of the photovoltaic module of the present invention;

[0040] Figure 2 The image shows the EL image of a photovoltaic module using the gridless conductive adhesive of the present invention after passing through a TC200.

[0041] Figure 3 EL diagram of a photovoltaic module using existing gridless adhesive after passing through TC200;

[0042] In the diagram, 1. Conductive fixing adhesive without main grid, 2. Interconnecting strip, 3. Photovoltaic cell. Detailed Implementation

[0043] Example 1: A gridless conductive adhesive comprising the following components by weight percentage:

[0044] 65% of the adhesive is used for fixing.

[0045] 25% conductive powder

[0046] 10% low-temperature solder particles;

[0047] Among them, the melting point of the low-temperature solder particles is 90℃~145℃, and the components are mixed to form a gridless conductive fixing adhesive 1.

[0048] The fixing adhesive comprises the following components, and the weight percentage of each component in the main grid-free conductive fixing adhesive 1 is as follows:

[0049] Bisphenol A epoxy resin 30%

[0050] 30% phenolic epoxy resin

[0051] 3% hot acid initiator

[0052] 2% thixotropic agent;

[0053] The conductive powder is nano-aluminum powder, the low-temperature solder particles are Si42Bi58 alloy, the hot acid initiator is triphenylsulfonate hexafluoroantimony salt, and the thixotropic agent is fumed silica thixotropic agent.

[0054] Mix the above components, stir and degas under vacuum to obtain the non-main grid conductive fixing adhesive 1.

[0055] A method for preparing a gridless photovoltaic module involves using the gridless conductive adhesive 1 of this embodiment 1 to connect the interconnect strip 2 to the photovoltaic cell 3. The gridless conductive adhesive 1 covers the overlapping area of ​​the interconnect strip 2 and the grid lines of the photovoltaic cell 3.

[0056] Interconnecting strip 2 is made of copper wire.

[0057] The highly cross-linked skin membrane is no longer covered on the interconnect strip 2.

[0058] During the lamination process, the lamination temperature melts the low-temperature solder particles in the non-main grid conductive fixing adhesive 1, thereby achieving alloy welding between the interconnect strip 2 and the battery grid line.

[0059] The interconnecting strip 2 is connected to the photovoltaic cell 3 by a strip-shaped non-main grid conductive fixing adhesive 1 extending along the length of the interconnecting strip 2.

[0060] like Figure 1 As shown, the specific process of connecting the interconnect strip 2 and the photovoltaic cell 3 using the aforementioned gridless conductive adhesive 1 is as follows:

[0061] Screen printing: A strip of gridless conductive adhesive 1 is printed in the interconnection strip 2 area of ​​the photovoltaic cell 3 using screen printing.

[0062] Series curing: The interconnecting strips 2 are laid on the photovoltaic cells 3, and the cured gridless conductive adhesive 1 connects the adjacent photovoltaic cells 3 into a series.

[0063] Example 2, a gridless conductive fixing adhesive, comprising the following components by weight percentage:

[0064] 45% of the adhesive is used for fixing.

[0065] 40% conductive powder

[0066] 15% low-temperature solder particles;

[0067] Among them, the melting point of the low-temperature solder particles is 90℃~145℃, and the components are mixed to form a gridless conductive fixing adhesive 1.

[0068] The fixing adhesive comprises the following components, and the weight percentage of each component in the main grid-free conductive fixing adhesive 1 is as follows:

[0069] Bisphenol A epoxy resin 20%

[0070] Alicyclic epoxy resin 20%

[0071] 3% hot acid initiator

[0072] 2% thixotropic agent;

[0073] The conductive powder is nano-copper powder, the low-temperature solder particles are Si42Bi58 alloy, the hot acid initiator is tetraphenylphosphonium tetraphenylborate, and the thixotropic agent is organic bentonite thixotropic agent.

[0074] Mix the above components, stir and degas under vacuum to obtain the non-main grid conductive fixing adhesive 1.

[0075] The preparation method of the gridless photovoltaic module using the gridless conductive fixing adhesive 1 in Example 2 is the same as that in Example 1.

[0076] Example 3, a gridless conductive fixing adhesive, comprising the following components by weight percentage:

[0077] 45% of the adhesive is used for fixing.

[0078] 40% conductive powder

[0079] 15% low-temperature solder particles;

[0080] Among them, the melting point of the low-temperature solder particles is 90℃~145℃, and the components are mixed to form a gridless conductive fixing adhesive 1.

[0081] The fixing adhesive comprises the following components, and the weight percentage of each component in the main grid-free conductive fixing adhesive 1 is as follows:

[0082] 10% phenolic epoxy resin

[0083] Alicyclic epoxy resin 30%

[0084] 3% hot acid initiator

[0085] 2% thixotropic agent;

[0086] The conductive powder is nano-iron powder, the low-temperature solder particles are Si42Bi58 alloy with a melting point of 138℃, the hot acid initiator is p-toluenesulfonic acid pyridine salt, and the thixotropic agent is polyamide wax thixotropic agent.

[0087] Mix the above components, stir and degas under vacuum to obtain the non-main grid conductive fixing adhesive 1.

[0088] The preparation method of the gridless photovoltaic module using the gridless conductive fixing adhesive 1 in Example 3 is the same as that in Example 1.

[0089] The difference from Examples 1 and 2 is that in Example 3, the interconnecting strip 2 is a welding wire with a low-temperature tin plating layer on its surface. During the lamination process, the lamination temperature melts the low-temperature solder particles and the low-temperature tin plating layer in the gridless conductive fixing adhesive 1, thereby achieving alloy welding between the welding wire and the battery grid line.

[0090] The principle by which the technical effects of the present invention can be achieved in Examples 1 to 3 is as follows:

[0091] 1. Low-temperature solder particles melt to achieve alloy welding between interconnect strip 2 and battery grid lines;

[0092] 2. The non-conductive fixing adhesive 1 is conductive, which can improve the conductivity of the interconnect strip 2 and the battery grid line and reduce the possibility of poor soldering;

[0093] 3. Even if the molten low-temperature solder particles are not used for soldering the interconnect strip 2 to the battery grid line, they can still increase the mechanical connection strength between the interconnect strip 2, the low-temperature solder particles, and the resin in the adhesive, thus preventing the interconnect strip 2 from losing contact with the battery grid line in TC200 due to the mechanical connection strength, which would lead to a cold solder joint.

[0094] 4. When the interconnect strip 2 is a solder wire with a tin plating layer, the low-temperature tin plating layer on the surface of the solder wire melts at the lamination temperature, and together with the molten low-temperature solder particles, the interconnect strip 2 and the battery grid line are alloyed and welded, reducing the possibility of poor soldering.

[0095] Example 4, a gridless conductive fixing adhesive, comprising the following components by weight percentage:

[0096] 65% of the adhesive is used for fixing.

[0097] 25% conductive powder

[0098] 10% low-temperature solder particles;

[0099] Among them, the melting point of the low-temperature solder particles is 90℃~145℃, and the components are mixed to form a gridless conductive fixing adhesive 1.

[0100] The fixing adhesive is an adhesive that can melt at low temperatures after curing, and it softens and flows at the lamination temperature of the photovoltaic module.

[0101] The lamination temperature of photovoltaic modules is generally 105℃~150℃, so the fixing adhesive will soften and flow at 105℃~120℃.

[0102] The fixing adhesive comprises the following components, and the weight percentage of each component in the main grid-free conductive fixing adhesive 1 is as follows:

[0103] 30% low temperature resin

[0104] 30% phenolic epoxy resin

[0105] 3% hot acid initiator

[0106] 2% thixotropic agent;

[0107] The conductive powder is nano-aluminum powder, the low-temperature solder particles are Si42Bi58 alloy, the hot acid initiator is triphenylsulfonate hexafluoroantimony salt, and the thixotropic agent is fumed silica thixotropic agent.

[0108] Mix the above components, stir and degas under vacuum to obtain the non-main grid conductive fixing adhesive 1.

[0109] The cured low-temperature resin will soften and flow at 105℃~120℃. The low-temperature resin is an epoxy-acrylic graft copolymer resin.

[0110] The preparation method of low-temperature resin includes the following steps:

[0111] (1) Mix 20g of methyl methacrylate (MMA), 20g of butyl acrylate (BA), 30g of acrylic acid (AA), 1.4g of BPO initiator, 5g of xylene, and 6g of ethyl acetate to prepare a monomer premix, wherein xylene and ethyl acetate are organic solvents.

[0112] (2) Add 50g of epoxy resin (E-51), 10g of xylene, and 12g of ethyl acetate to a four-necked flask equipped with a stirrer, thermometer, condenser, dropping funnel and nitrogen protection. Xylene and ethyl acetate are organic solvents.

[0113] (3) After the epoxy resin solution temperature stabilizes at 110±2℃, start adding the monomer premix prepared in the first step at a uniform rate through the dropping funnel, and control the dropping time to 2 to 3 hours;

[0114] (4) After the monomer is added, add 1.4g of BPO initiator and keep the reaction at 110℃~115℃ for 2~3 hours to allow the monomer to fully polymerize. The 1.4g of BPO initiator added is dissolved in 2g of xylene solvent before being added.

[0115] (5) Add 0.5g of catalyst to the system obtained in step (4), and monitor the reaction progress by periodically sampling and measuring the acid value (AV). When the acid value drops below 5mgKOH / g and is basically stable, the reaction is considered to have stopped. The catalyst is triphenylphosphine.

[0116] (6) After the reaction stops, the organic solvent is removed by distillation, and the material is collected by filtration after cooling to obtain epoxy-acrylic grafted resin.

[0117] Interconnecting strip 2 is made of copper wire.

[0118] The preparation method of the gridless photovoltaic module using the gridless conductive fixing adhesive 1 of this embodiment 4 is the same as that of embodiment 1.

[0119] The EL image of the photovoltaic module prepared in Example 4 after passing through TC200 is shown below. Figure 2 As shown in the EL diagram, no cold solder joints were observed.

[0120] Example 5, a gridless conductive fixing adhesive, comprising the following components by weight percentage:

[0121] 45% of the adhesive is used for fixing.

[0122] 40% conductive powder

[0123] 15% low-temperature solder particles;

[0124] Among them, the melting point of the low-temperature solder particles is 90℃~145℃, and the components are mixed to form a gridless conductive fixing adhesive 1.

[0125] The fixing adhesive is an adhesive that can melt at low temperatures after curing, and it softens and flows at the lamination temperature of the photovoltaic module.

[0126] The lamination temperature of photovoltaic modules is generally 105℃~150℃, so the fixing adhesive will soften and flow at 105℃~120℃.

[0127] The fixing adhesive comprises the following components, and the weight percentage of each component in the main grid-free conductive fixing adhesive 1 is as follows:

[0128] 20% low temperature resin

[0129] Alicyclic epoxy resin 20%

[0130] 3% hot acid initiator

[0131] 2% thixotropic agent;

[0132] The conductive powder is nano-copper powder, the low-temperature solder particles are Si42Bi58 alloy, the hot acid initiator is tetraphenylphosphonium tetraphenylborate, and the thixotropic agent is organic bentonite thixotropic agent.

[0133] Mix the above components, stir and degas under vacuum to obtain the non-main grid conductive fixing adhesive 1.

[0134] Interconnecting strip 2 is made of copper wire, but other conductive metal wires with excellent conductivity cannot be excluded.

[0135] The preparation method of the low-temperature resin in the gridless conductive fixing adhesive 1 of this embodiment 5 is the same as that in embodiment 1.

[0136] The preparation method of the gridless photovoltaic module using the gridless conductive fixing adhesive 1 of this embodiment 5 is the same as that of embodiment 1.

[0137] Example 6, a gridless conductive fixing adhesive, comprising the following components by weight percentage:

[0138] 45% of the adhesive is used for fixing.

[0139] 40% conductive powder

[0140] 15% low-temperature solder particles;

[0141] Among them, the melting point of the low-temperature solder particles is 90℃~145℃, and the components are mixed to form a gridless conductive fixing adhesive 1.

[0142] The fixing adhesive is an adhesive that can melt at low temperatures after curing, and it softens and flows at the lamination temperature of the photovoltaic module.

[0143] The lamination temperature of photovoltaic modules is generally 105℃~150℃, so the fixing adhesive will soften and flow at 105℃~120℃.

[0144] The fixing adhesive comprises the following components, and the weight percentage of each component in the main grid-free conductive fixing adhesive 1 is as follows:

[0145] 10% of low-temperature resin

[0146] Alicyclic epoxy resin 30%

[0147] 3% hot acid initiator

[0148] 2% thixotropic agent;

[0149] The conductive powder is nano-copper powder, the low-temperature solder particles are Si42Bi58 alloy, the hot acid initiator is tetraphenylphosphonium tetraphenylborate, and the thixotropic agent is organic bentonite thixotropic agent.

[0150] Mix the above components, stir and degas under vacuum to obtain the non-main grid conductive fixing adhesive 1.

[0151] Interconnecting strip 2 is welding wire.

[0152] The preparation method of the low-temperature resin in the gridless conductive fixing adhesive 1 of this embodiment 6 is the same as that in embodiment 1.

[0153] The preparation method of the gridless photovoltaic module using the gridless conductive fixing adhesive 1 of this embodiment 6 is the same as that of embodiment 1.

[0154] The principle by which the technical effects of the present invention can be achieved in Examples 4 to 6 is as follows:

[0155] 1. Low-temperature solder particles melt to achieve alloy welding between interconnect strip 2 and battery grid lines;

[0156] 2. The non-conductive fixing adhesive 1 is conductive, which can improve the conductivity of the interconnect strip 2 and the battery grid line and reduce the possibility of poor soldering;

[0157] 3. Even if the molten low-temperature solder particles are not used for soldering the interconnect strip 2 to the battery grid line, they can still increase the mechanical connection strength between the interconnect strip 2, the low-temperature solder particles, and the resin in the adhesive, thus preventing the interconnect strip 2 from losing contact with the battery grid line in TC200 due to the mechanical connection strength, which would lead to a cold solder joint.

[0158] 4. The conductive fixing adhesive 1 without main grid can flow during lamination, which helps the interconnect strip 2 to contact the battery grid line during lamination. Therefore, the good contact between the interconnect strip 2 and the battery grid line helps to reduce the resistance between the interconnect strip 2 and the battery grid line.

[0159] 5. Whether it is dispensing or printing, the adhesive is narrow at the top and wide at the bottom. The non-main grid conductive fixing adhesive 1 can flow during lamination, which increases the contact area between the non-main grid conductive fixing adhesive 1 and the interconnect strip 2 and photovoltaic cell 3, improves mechanical strength, and prevents the interconnect strip 2 from losing contact with the cell grid line in TC200 due to mechanical connection strength, resulting in poor soldering.

[0160] Epoxy resin softens and has low fluidity at lamination temperature. In the photovoltaic modules of Examples 1-3, only slight solder joints were observed in the EL graph after the subsequent TC200 thermal cycling test. However, compared with photovoltaic modules using existing non-conductive grid-free fixing adhesive and skin film, the solder joint situation was greatly improved.

[0161] In embodiments 4-6, regardless of whether the interconnecting strip 2 uses welding wire or copper wire, the photovoltaic module, after subsequent TC200 thermal cycling tests, will... Figure 3 As shown in the EL diagram, there are virtually no cold solder joints.

[0162] In embodiments 4 to 6, epoxy resin can be used to improve the adhesion to the interconnect strip 2 and the photovoltaic cell 3, and to prevent adhesive breakage during lamination and string transfer.

[0163] In the prior art, although the low-temperature tin plating layer on the surface of the solder wire melts during lamination to achieve alloy welding between the solder wire and the battery grid line, the amount of tin plating layer on the surface of the solder wire is small, resulting in low mechanical strength of the weld with the battery grid line. However, the alloy welding formed by the low-temperature solder particles in the gridless conductive fixing adhesive of the present invention has a relatively larger amount of solder, so the quality of the alloy welding formed is also better.

Claims

1. A gridless conductive fixing adhesive, characterized in that, Includes the following components by weight percentage: Fixative adhesive 21%–78% Conductive powder 10%–40% Low-temperature solder particles: 10%–40%; The low-temperature solder particles have a melting point of 90℃~145℃, and the components are mixed to form a gridless conductive fixing adhesive.

2. The gridless conductive fixing adhesive according to claim 1, characterized in that: The fixing adhesive comprises the following components, and the weight percentage of each component in the gateless conductive fixing adhesive is as follows: Epoxy resin 20%–70% Hot acid initiator 0.5%–3% Thixotropic agent 0.5%–5%.

3. The gridless conductive fixing adhesive according to claim 1, characterized in that: The fixing adhesive is an adhesive that can melt at low temperatures after curing, and it softens and flows at the lamination temperature of the photovoltaic module.

4. The gridless conductive fixing adhesive according to claim 1, characterized in that: The fixing adhesive is an adhesive that can melt at low temperatures after curing, and it softens and flows at 105℃~120℃.

5. The gridless conductive fixing adhesive according to claim 3 or 4, characterized in that: The fixing adhesive comprises the following components, and the weight percentage of each component in the gateless conductive fixing adhesive is as follows: Low-temperature resin 10%–30% Epoxy resin 10%–40% Hot acid initiator 0.5%–3% Thixotropic agent 0.5%–5%; The cured low-temperature resin softens and flows at 105℃~120℃, and the low-temperature resin is an epoxy-acrylic graft copolymer resin.

6. The gridless conductive fixing adhesive according to claim 1, characterized in that: The conductive powder is one or more of nano-iron powder, aluminum powder, conductive graphite, and copper powder. The low-temperature solder particles are tin-bismuth alloy powder.

7. The gridless conductive fixing adhesive according to claim 5, characterized in that: The epoxy resin is one or more of bisphenol A type epoxy resin, alicyclic epoxy resin, phenolic epoxy resin and oxetane.

8. The gridless conductive fixing adhesive according to claim 2 or 5, characterized in that: The thermal acid initiator is one or more of hexafluoroantimonate, aromatic sulfonate, and phosphonium salt; The thixotropic agent is one or more of fumed silica, organobentonite, and polyamide wax.

9. The gridless conductive fixing adhesive according to claim 5, characterized in that: The preparation method of the low-temperature resin includes the following steps: (1) Under an inert atmosphere, the epoxy resin solution is heated to 108℃~112℃, and then the monomer premix is ​​added dropwise at a uniform rate. After the addition is complete, the reaction is kept at 110℃~115℃ for 2~3 hours to allow the monomer to fully polymerize. (2) Add a catalyst to the system obtained in step (1) and monitor the reaction progress by periodically measuring the acid value of the reaction system; (3) After the reaction stops, the organic solvent is removed to obtain the epoxy-acrylic grafted resin; Among them, the epoxy resin solution is a solution formed by dissolving epoxy resin in an organic solvent; The monomer premix is ​​a mixture of methyl methacrylate, butyl acrylate, acrylic acid, BPO initiator and organic solvent.

10. A method for fabricating a gridless photovoltaic module, characterized in that: The interconnect strip and the photovoltaic cell are connected using the gridless conductive adhesive described in claim 1, wherein the gridless conductive adhesive covers the overlapping area of ​​the interconnect strip and the grid lines of the photovoltaic cell.

11. The method for preparing a gridless photovoltaic module according to claim 10, characterized in that: The interconnecting strip is connected to the photovoltaic cell by a strip-shaped, gridless conductive adhesive extending along the length of the interconnecting strip.

Images