Preparation method of photovoltaic laminated piece and photovoltaic module

Abstract

The invention provides a preparation method of a photovoltaic laminated part and a photovoltaic module. The preparation method comprises the following steps: providing a plurality of battery pieces and solder strips, and coating solder on bonding pads of the battery pieces; corresponding welding strips are fixed on the bonding pads to be electrically connected, so that the plurality of battery pieces form a battery string through the welding strips; laminating the cover plate, the front packaging adhesive film, the battery string, the back packaging adhesive film and the back plate in sequence to obtain a laminated part; heating the laminated part at a first preset temperature to form a combined part; heating the assembly at a second preset temperature to form a laminated part; the first preset temperature is higher than the melting point of the front packaging adhesive film and the back packaging adhesive film, but is lower than the melting point of the welding flux on the battery piece and the welding flux on the welding strip; the second preset temperature is higher than the melting point of the solder on the battery piece and the solder on the solder strip. According to the preparation method, the problem of battery piece warping in a high-temperature welding process and the problem of poor welding reliability in a low-temperature welding process are avoided at the same time.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a method for preparing a photovoltaic laminate and a photovoltaic module. Background Art

[0002] The statements in this section merely provide background art related to the present invention and do not necessarily constitute prior art.

[0003] In the preparation process of a photovoltaic module, the grid line current of each cell needs to be collected and exported through a solder strip. Solder pads are formed on each grid line of the cell, and the solder strip is electrically connected to each solder pad to be connected by welding. During the above welding process, the cells are strung together by the solder strip. After the cell strings are electrically connected to form a cell string array, they are laminated together with the encapsulation structure to form a photovoltaic laminate.

[0004] In the related art, during the preparation process of a photovoltaic laminate, the welding effect between the solder strip and the cell is poor, which may lead to a decrease in the yield and reliability of the photovoltaic module. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a photovoltaic laminate and a photovoltaic module to improve the reliability of the photovoltaic module.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a photovoltaic laminate, including:

[0008] Providing a plurality of cells and solder strips, wherein solder is coated on the solder pads of the cells;

[0009] Fixing the corresponding solder strips on each of the solder pads to be electrically connected, so that a plurality of the cells form a cell string through the solder strips;

[0010] Stacking in the order of a cover plate, a front encapsulation film, the cell string, a back encapsulation film, and a back plate to obtain a stacked member;

[0011] Heating the stacked member at a first preset temperature to form a combined member;

[0012] Heating the combined member at a second preset temperature to form a laminate;

[0013] The first preset temperature is higher than the melting points of the front encapsulation film and the back encapsulation film, but lower than the melting points of the solder on the cells and the solder on the solder strips;

[0014] The second preset temperature is higher than the melting points of the solder on the cells and the solder on the solder strips.

[0015] According to at least one embodiment of the present invention, when providing a plurality of solar cells and solder tapes, it includes:

[0016] Print the solder on the pads of the solar cells.

[0017] According to at least one embodiment of the present invention, when fixing the corresponding solder tapes on the respective pads to be electrically connected, it includes:

[0018] Apply an adhesive between the solder tape and the solar cell to fix the solder tape; or,

[0019] Use positioning tape to fix the solder tape on the solar cell.

[0020] According to at least one embodiment of the present invention, the first preset temperature is 130°C to 150°C.

[0021] According to at least one embodiment of the present invention, the preparation method includes: laminating the laminate in a photovoltaic laminator under a temperature condition of 130°C to 150°C to form the assembly.

[0022] According to at least one embodiment of the present invention, after laminating the laminate including the battery string to form an assembly, the preparation method includes:

[0023] Use one of a photovoltaic laminator, an oven, a flat hot press, or a laser welding machine to heat the assembly.

[0024] According to at least one embodiment of the present invention, the solar cell includes one of a back contact solar cell, a heterojunction solar cell, or a TOPCon solar cell.

[0025] According to at least one embodiment of the present invention, when the solar cell includes a back contact solar cell, before fixing the corresponding solder tapes on the respective pads to be electrically connected, the preparation method further includes:

[0026] Among the respective pads located under the same solder tape, cover the remaining pads except those to be electrically connected with an insulating structure.

[0027] According to at least one embodiment of the present invention, when laminating the laminate including the battery string to form an assembly, it includes:

[0028] Arrange a plurality of the battery strings in an array and connect them in series or parallel to form a battery string array, and form a laminate including the battery string array.

[0029] According to at least one embodiment of the present invention, the second preset temperature is 15% to 25% higher than the first preset temperature.

[0030] According to at least one embodiment of the present invention, the second preset temperature is 5% - 20% higher than the melting points of the solder on the cell and the solder on the solder strip.

[0031] According to at least one embodiment of the present invention, the melting points of the solder on the cell and the solder on the solder strip are 160°C - 180°C.

[0032] According to at least one embodiment of the present invention, the second preset temperature is 170°C - 190°C.

[0033] In a second aspect, the present invention further provides a photovoltaic module, including a photovoltaic laminate and a frame surrounding the circumferential edge of the photovoltaic laminate, and the photovoltaic laminate is prepared by the preparation method described in the first aspect.

[0034] Among one or more technical solutions provided in the exemplary embodiments of the present invention, at least one of the following beneficial effects can be achieved.

[0035] In the preparation method of the photovoltaic laminate of the exemplary embodiment of the present invention, the solder strip is first fixed on the pads to be connected of the cells to form a cell string, the cell string is stacked with a cover plate, a front encapsulation film, a back encapsulation film and a backplane to form a stacked member, and then the stacked member is heated at a first preset temperature higher than the melting point of the front and back encapsulation films but lower than the melting temperature of the solder on the cells and the solder on the solder strip to obtain a combined member. During the first heating process, the front encapsulation film and the back encapsulation film melt and crosslink. Since the first preset temperature is lower than the melting temperature of the solder, after the first heating, the solder strip and the cells are in a tightly attached physical crimping state, but no alloying occurs. Then the combined member is heated at a second preset temperature higher than the melting point of the solder. During the second heating process, the solder on the solder strip and the solder on the cell pads melt and alloy, so that an electrical connection is formed between the solder strip and the cells.

[0036] Based on this, compared with the high-temperature welding process in the prior art, which welds the solder strip and the cells before laminating the combined member, and the instantaneous high-temperature welding stress will cause the cells to warp and result in void soldering. The welding process of the exemplary embodiment of the present invention pre-fixes the solder strip and the cells before laminating the combined member and heats after laminating the combined member. At this time, the cells have been encapsulated in the encapsulation structure and the heating temperature does not exceed the preset temperature. On the one hand, the encapsulation structure avoids the problem of cell warping; on the other hand, it reduces the temperature of the instantaneous high temperature, thereby reducing the occurrence of void soldering and improving the yield of the photovoltaic module.

[0037] Compared with the existing low-temperature welding process, the use of low-temperature solder and low-temperature solder tape enables the welding temperature to be below the lamination temperature, so that the welding between the solder tape and the solar cell is completed while the assembly is laminated in the laminator. Low-temperature solder and low-temperature solder tape need to add bismuth (Bi) element to the tin alloy to reduce the tin melting temperature, but the Bi element will make the solderability of the low-temperature solder tape and low-temperature solder with the solder pad (usually formed by silver grid lines) worse. The alloying layer after welding is brittle and has low tensile strength, resulting in poor reliability of the photovoltaic module. Further, since the tin melting temperature of the low-temperature solder tape and low-temperature solder is below the hot spot temperature of the photovoltaic module, there is also a risk of failure during the service of the photovoltaic module. In the method for preparing a photovoltaic laminate according to an exemplary embodiment of the present invention, the welding temperature of the solder tape and solder is higher than the lamination temperature, that is, low-temperature solder tape and low-temperature solder without adding Bi element are not used, so there is no problem of poor solderability, which improves the reliability of the photovoltaic module. On the other hand, since the welding temperature of the solder tape and solder, that is, the tin melting temperature, is higher than the hot spot temperature of the photovoltaic module, the failure risk of the photovoltaic module is reduced. Based on this, compared with the welding reliability problem of the low-temperature welding process that cannot be used in the single-glass process, the welding reliability in the method for preparing a photovoltaic laminate according to an exemplary embodiment of the present invention is high, and it can be applied to single-glass or double-glass processes, with a wider application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings illustrate exemplary embodiments of the present invention and, together with the description, are used to explain the principles of the present invention. The drawings are included to provide a further understanding of the present invention and are incorporated in this specification and form a part of this specification;

[0039] Figure 1 is a schematic flow chart of a method for preparing a photovoltaic laminate according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] In the photovoltaic field, there are various types of batteries. For example, Tunnel Oxide Passivated Contact (TOPCon) batteries, Heterojunction with Intrinsic Thin-layer (HJT), Perovskite Solar Cell (PSC), and Back Contact (BC) photovoltaic cells.

[0042] Since both the positive and negative grid lines of BC cells are arranged on the back of the cell, there is no need to consider the problem of grid line occlusion, and the metal grid line structure can be optimized to the greatest extent. For example, the grid line width can be appropriately increased and the grid line shape can be optimized to reduce the series resistance of the cell, and the back reflection function of long-wavelength photons can be enhanced, thereby improving the fill factor and short-circuit current of the cell. BC cells are more convenient for module packaging. They can be coplanarly connected to the module through automated operations. Unlike traditional cells, there is no need to connect the front main grid of one cell to the back main grid of another cell during solder ribbon series connection, which can also reduce the adverse effects caused by pressure deformation.

[0043] BC cell technology can also be combined with technologies such as TOPCon, HJT, and perovskite, with good compatibility, to further improve the photoelectric conversion efficiency. Thus, various types of BC cells have been derived, such as Tunneling oxide passivated contact BackContact (TBC), Interdigitated Back Contact (IBC), Heterojunction BackContact (HBC), etc.

[0044] In related technologies, in the method for manufacturing a BC cell photovoltaic module, the solder ribbon and the cell are fixedly connected by high-temperature welding. Specifically, insulating glue is used to isolate the opposite grid line electrodes on the back of the BC cell, high-temperature solder (usually high-temperature solder paste) is printed on the pads of the positive and negative grid lines, and then the high-temperature solder ribbon is laid above the high-temperature solder paste, and the solder paste is instantaneously heated and welded using an infrared lamp tube or laser energy, and the temperature is usually between 200°C and 300°C. Since the high-temperature solder paste, the positive and negative grid lines, the insulating structure, and the solder ribbon are all located on the back of the BC cell, the welding stress during the above-mentioned instantaneous heating and welding process will cause the BC cell to warp, and it is difficult to avoid the occurrence of void soldering between the solder ribbon and the pad. Further, in the subsequent production process of the photovoltaic module, warping of the cell is more likely to cause hidden cracks, parallel connection, or even fragmentation, resulting in an increase in the defect rate of the photovoltaic module.

[0045] In the related art, in order to avoid the occurrence of hidden crack problems caused by the warping of solar cells, a low-temperature welding process is adopted. Specifically, a low-temperature solder (usually low-temperature solder paste) is printed on the pads of the positive and negative main grids, and a low-temperature solder tape is laid on the pads coated with the low-temperature solder paste. The welding temperature can be lower than the lamination temperature. Therefore, during the subsequent lamination process, the welding between the solder tape and the solar cell is achieved by using the lamination temperature, avoiding the problems caused by instantaneous heating welding. However, in the above-mentioned low-temperature solder paste and low-temperature solder tape, bismuth (Bi) element needs to be added to reduce the welding temperature below the lamination temperature. The addition of Bi element will make the solderability of the solder tape, solder paste and pads (usually formed by silver grid lines) worse. After lamination welding, the alloy layer between the solder tape and the pads is brittle and has little tensile strength, with the risk of de-welding, which will lead to poor reliability of the photovoltaic module and cannot be applied to the single-glass route. At the same time, due to the relatively low tin melting temperature at the solder joints, the solder joints will come apart at the temperature of the high hot spot of the photovoltaic module during service, and there is a risk of failure of the photovoltaic module.

[0046] In view of the above problems, the method for preparing a photovoltaic laminate according to an exemplary embodiment of the present invention divides the heating process in the preparation process of the photovoltaic laminate into two heating steps, namely low-temperature heating and high-temperature heating, thus avoiding the warping problem of solar cells caused by high-temperature welding and the problem of poor reliability of low-temperature welding, and improving the reliability of the photovoltaic module.

[0047] It should be noted that the method for preparing a photovoltaic laminate according to an exemplary embodiment of the present invention is not only applicable to BC solar cells, but also applicable to other types of solar cells. Hereinafter, BC solar cells will be taken as an example for illustration.

[0048] Figure 1 is a schematic flow chart of the method for preparing a photovoltaic laminate according to an embodiment of the present invention. Referring to Figure 1 As shown, the method for preparing a photovoltaic laminate provided by an exemplary embodiment of the present invention includes the following steps:

[0049] Step 101: Provide a plurality of solar cells and solder tapes, wherein, solder is coated on the pads of the solar cells.

[0050] The photovoltaic solar cell can be a square whole solar cell or a rectangular sliced solar cell. The front side of the solar cell is the light-receiving surface, and the back side is the light-blocking surface. On the back side of the solar cell, a positive grid line and a negative grid line are arranged, wherein at least part of the positive grid line and at least part of the negative grid line are alternately arranged along a first direction, and pads are formed on each grid line for welding connection with the corresponding solder tape, wherein the first direction refers to the extending direction of the solder tape.

[0051] The same solder tape is connected to the pads on the same-polarity grid lines, and needs to be electrically isolated from the pads on the different-polarity grid lines. Therefore, an insulating structure needs to be provided to cover the different-polarity grid lines (pads) spanned by the same solder tape.

[0052] Exemplarily, among the pads located under the same solder ribbon, the remaining pads other than those to be electrically connected are isolated from the solder ribbon electricity using insulating tape; or the back side of the cell has insulating glue to insulate other pads except the pads to be connected to the solder ribbon, preventing the same solder ribbon from forming a welded connection with grid lines of different polarities.

[0053] Exemplarily, the above grid lines can be main grid lines or fine grid lines on the cell.

[0054] Step 102: Fix corresponding solder ribbons on the pads to be electrically connected, so that multiple cells form a cell string through the solder ribbons.

[0055] It should be noted that in this step, the connection between the solder ribbon and the pad on the cell is a physical connection, and it only needs to fix the position of the solder ribbon and the cell, and no displacement occurs in subsequent steps.

[0056] In practical applications, multiple cells are laid sequentially along the first direction, and solder paste is coated on the pads of the grid lines to be connected by means of screen printing. Exemplarily, after printing the solder paste, it is dried at a temperature of 120°C for 5 minutes.

[0057] Exemplarily, the solder paste can be solder paste, which is composed of tin alloy powder and flux. The flux can include tackifier, solvent, organic acid activator and thickening thixotropic agent.

[0058] Then, solder ribbons are laid on each row of pads coated with solder paste to be connected, forming multiple solder ribbons arranged along the second direction. The second direction is perpendicular to the first direction, and the second direction can be the extending direction of the grid lines.

[0059] Before laying the solder ribbon, glue dots (such as adhesives like UV glue, hot melt glue, etc.) can be applied on the cells between the grid lines, and the solder ribbon is fixed on the cell by curing the dot glue with a UV lamp to achieve physical lapping and fixing of the solder ribbon and the pad of the cell.

[0060] Optionally, after laying the solder ribbon on the cell, positioning tape is used to fix the solder ribbon on the cell, so that the solder ribbon forms physical lapping with the corresponding pad.

[0061] The solder tape generally includes a base material and a solder layer coated on the outer surface of the base material. Exemplarily, the solder tape can be composed of a copper base material and a tin alloy coating. The copper base material can be a copper flat tape, and its material can be refined tough oxygen-free copper / T2 purple copper, with a copper content of ≥99.99% and a conductivity of ≥98%. The tin alloy coating is 63% Sn (tin) 37% Pb (lead), 60% Sn 40% Pb; the coating thickness can be a single-sided coating thickness of 0.01 mm to 0.05 mm, such as 0.02 mm, 0.03 mm, 0.04 mm.

[0062] Optionally, the above tin alloy coating is 63% Sn 35% Pb 2% Ag; the coating thickness can be a single-sided coating thickness of 0.01 mm to 0.05 mm.

[0063] The composition of the tin alloy powder in the solder coated on the solder pads of the battery cells can be the same as that of the tin alloy coating of the solder tape. Exemplarily, the melting point (tin melting temperature) of the solder and the tin alloy coating of the solder tape can be 160°C to 180°C, such as 161°C, 163°C, 165°C, 167°C, 170°C, 173°C, 175°C, 179°C, etc.

[0064] It should be noted that the length of the solder tape can be twice or more the width of the battery cell in the first direction, so that two adjacent battery cells share the same solder tape, forming the connection of two adjacent battery cells through multiple shared solder tapes. Thus, multiple battery cells are connected in sequence to form a battery string.

[0065] Step 103: Stack in the order of the cover plate, the front encapsulation film, the battery string, the back encapsulation film, and the backplane to obtain a stacked component.

[0066] During the stacking process, lay the front encapsulation film on the cover glass, lay the battery string array on the front encapsulation film with the back of the battery string array facing up, then lay the back encapsulation film on the back of the battery string array, and then lay the backplane to form a stacked component.

[0067] Among them, the steps of laying the battery string array include: arranging multiple battery strings in an array according to a preset pattern, and then welding the busbars to connect the battery strings in parallel or in series to form a battery string array.

[0068] In practical applications, arrange multiple battery strings in a row along the second direction to form a battery string group, and arrange two battery string groups in a row along the first direction to form a battery string array; and through the welding between the busbar and the solder tape, for example, the extending direction of the busbar straddles multiple solder tapes extending out of the battery string and forms a weld with them. Among them, there can be three busbars, two busbars are located at one end where the two battery string groups are far from each other, and one busbar is located between the two battery string groups, so as to connect the adjacent battery strings in series or in parallel.

[0069] The cover plate is usually tempered glass, and the back plate can be tempered glass or an organic polymer material. When the back plate is tempered glass, the laminate can form a double-glass module. When the back plate is an organic polymer material, the laminate can form a single-glass module.

[0070] Among them, the organic polymer material used as the back plate is usually composed of multiple layers of materials with different functions, such as polyethylene glycol terephthalate (PET) polyester film, fluorine materials: poly(vinyl formal), etc.

[0071] Exemplarily, the above-mentioned front encapsulation film and back encapsulation film can be ethylene-vinyl acetate copolymer (EVA) film, or polyolefin elastomer (POE) film, EVA / POE laminate film, EVA / POE / EVA laminate film or POE / EVA / POE laminate film. The front encapsulation film and the back encapsulation film can be the same or different.

[0072] Step 104: Heat the laminate at a first preset temperature to form a combined component. The first preset temperature is higher than the melting points of the front encapsulation film and the back encapsulation film, but lower than the melting points of the solder on the battery cells and the solder on the solder tapes.

[0073] In this step, since the first preset temperature is higher than the melting points of the front encapsulation film and the back encapsulation film, the encapsulation film will melt and crosslink, bonding the cover plate, the battery string and the back plate together. At the same time, the first preset temperature is lower than the melting points of the solder on the battery cells and the solder on the solder tapes, so the solder will not melt during this heating, and the solder tape and the battery cell are in a tightly fitted physical crimping state, but no alloying occurs. At the same time, under the encapsulation of the encapsulation film, the position between the battery cell and the solder tape is fixed, providing a basis for avoiding the warping of the battery cell in the subsequent welding process.

[0074] The above laminate can be heated in a laminator to form a combined component.

[0075] In practical applications, in the laminator, under the action of heat and pressure, the front film and the back film are melted, and a firm bond is formed between the layers, thereby forming a combined component. Specifically, the first preset temperature can be 130°C to 150°C, and exemplarily 131°C, 133°C, 135°C, 137°C, 140°C, 143°C, 145°C, 147°C, 149°C, etc.

[0076] It can be understood that when the front encapsulation film and the back encapsulation film are made of different materials and thus have different melting points, the first preset temperature should be higher than the higher melting point, so that both the front encapsulation film and the back encapsulation film can be fully melted and cross-linked, better playing the role of encapsulation.

[0077] When the solder on the cell pad and the solder on the surface of the solder tape have different melting points due to different compositions, the first preset temperature should be lower than the lower melting point, so as to avoid the solder melting when the cell and the solder tape are not firmly fixed, causing the pad and the solder tape to be misaligned and affecting the welding effect in the subsequent second heating process.

[0078] Step 105: Heat the assembly at a second preset temperature to form a laminate. The second preset temperature is higher than the melting points of the solder on the cell and the solder on the solder tape.

[0079] In this step, the solder on the solder tape and the solder on the cell pad melt and alloy, forming an electrical connection between the solder tape and the cell.

[0080] Exemplarily, the heating method of the assembly in this step can be completed by any one of a photovoltaic laminator, an oven, a flat hot press or a laser welding machine for the alloying process.

[0081] When the heating temperature is the above temperature, since it is higher than the melting point (tin melting temperature) of the solder tape and the solder, it can enable complete alloying between the solder tape and the pad, with high reliability. And compared with the traditional high-temperature welding process that requires instantaneous high-temperature heating (usually at 200°C - 300°C), by using the preparation method provided in the embodiment of the present invention, the solder tape and the cell are heated more uniformly, reducing the possibility of the cell warping.

[0082] At the same time, the step of heating the assembly is placed after the lamination process. After the lamination process, the cell in the assembly is encapsulated between the cover plate and the back plate, and it is difficult for the cell to warp even at this heating temperature, ensuring the alloying process between the solder tape and the pad and improving the reliability.

[0083] Further, in step 104, after heating at the first preset temperature, the encapsulation adhesive films on the front and back sides undergo a crosslinking reaction, resulting in an increase in melting point and a decrease in fluidity. In step 105, it is sufficient to achieve solder melting and alloying at the second preset temperature. If the second preset temperature is too high, the encapsulation adhesive films on the front and back sides will completely melt again and become fluid, leading to misalignment between the solder ribbons and the pads. The second preset temperature can be 5% - 20% higher than the melting points of the solder on the cell pads and the solder on the solder ribbons, such as 7%, 9%, 10%, 11%, 13%, 15%, 17%, 19%, etc. It can be understood that when the melting points of the solder on the cell pads and the solder on the surface of the solder ribbons are different due to different compositions, the second preset temperature is 5% - 20% higher than the higher melting point, enabling the solder on the pads and the solder on the solder ribbons to be fully melted and alloyed. At the same time, the second preset temperature can be 15% - 25% higher than the first preset temperature, such as 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, etc.

[0084] For a tin alloy with a melting point in the range of 160°C - 180°C, considering the alloying of the solder and the fluidity of the adhesive film during the second heating process comprehensively, the second preset temperature can be 170°C - 190°C, such as 171°C, 173°C, 175°C, 177°C, 180°C, 183°C, 185°C, 187°C, 189°C, etc. For example, for a tin alloy with a melting point of 160°C, the second preset temperature can be 170°C, 175°C, 180°C, 185°C, 190°C, etc.; for a tin alloy with a melting point of 170°C, the second preset temperature can be 180°C, 185°C, 190°C, etc.; for a tin alloy with a melting point of 180°C, the second preset temperature can be 190°C. The heating time can be 5 min - 15 min, such as 7 min, 9 min, 10 min, 11 min, 13 min, etc.

[0085] During the service process of the photovoltaic module, the temperature range of hot spots is around 140°C. As the size of the photovoltaic module increases, the temperature of the hot spots will increase, even reaching 150°C. In the exemplary embodiments of the present invention, a tin alloy with a tin melting temperature in the range of 160°C - 180°C can be used as the solder for the solder ribbons and the pads. Outside the hot spot temperature range, even if the photovoltaic module has a hot spot problem, the electrical connection between the solder ribbons and the cells can still be maintained, greatly reducing the risk of failure of the photovoltaic module caused by hot spots. If the low-temperature soldering technology in the prior art is used, a tin alloy with a tin melting temperature in the range of about 130°C - 150°C needs to be selected as the solder for the solder ribbons and the pads, which completely falls within the hot spot temperature range. When the photovoltaic module has a hot spot problem, the low-temperature solder will also melt, affecting the electrical connection between the solder ribbons and the cells, and the risk of failure of the photovoltaic module caused by hot spots increases sharply.

[0086] It can be seen from this that in the method for preparing a photovoltaic laminate provided by the exemplary embodiment of the present invention, after physically positioning the solder tape on the battery chip to form a laminate, the heating alloying process is carried out after lamination, so that the battery chip does not have the warping of the battery chip caused by the instantaneous high temperature in the high-temperature welding process, and the problems of hidden cracks, parallel chips, and cracked chips of the battery chip during the lamination process can be solved; by increasing the tin melting temperature of the solder tape and the solder and being less than the welding temperature of the high-temperature welding process, the problem of small welding tensile force caused by the addition of Bi element in the low-temperature welding process is avoided; at the same time, the solder joint has a high tin melting temperature and can resist the hot spot temperature of the photovoltaic module, with higher reliability.

[0087] In a specific embodiment, the method for preparing a photovoltaic module includes:

[0088] S1. Provide a plurality of back-contact battery chips, solder paste, and solder tapes (tin melting temperature 170 °C), wherein the battery chips are back-contact battery chips containing insulating glue;

[0089] S2. Coat the solder paste on the pads of the grid lines of the battery chip by screen printing; dry it at 120 °C for 5 min after printing;

[0090] S3. Lay a plurality of battery chips along the first direction;

[0091] S4. Place the solder tape above the pad and bond it to the battery chip by means of dispensing, initially realizing that the position of the solder tape does not move, and at the same time forming a battery string by connecting a plurality of battery chips through the solder tape;

[0092] S5. Lay a front encapsulation film on the cover glass, lay a plurality of battery strings along the second direction on the front encapsulation film according to a preset pattern to form a battery string group, arrange two battery string groups along the first direction to form a battery string array, and connect adjacent battery strings in series or parallel through the welding between the bus bar and the solder tape, with the back of the battery string facing up; then lay a back encapsulation film on the back of the battery string array, and then lay a back plate glass to form a laminate;

[0093] S6. In a laminator, heat the laminate at 145 °C and then laminate it to form a combined component, and the solder tape of the combined component and the solder paste on the pad are in a physical press-fit state;

[0094] S7. Heat the combined component in a flat hot press at 180 °C for 10 min to realize the alloying between the solder tape and the pad, and complete the photovoltaic laminate with effective electrical connection;

[0095] S8. Install a frame around the photovoltaic laminate, and install a junction box on the back glass to form a photovoltaic module.

[0096] An exemplary embodiment of the present invention further provides a photovoltaic module, including a photovoltaic laminate and a frame surrounding the circumferential edge of the photovoltaic laminate, and the photovoltaic laminate is prepared by the method for preparing a photovoltaic laminate in the above embodiment.

[0097] The technical advantages of the above photovoltaic module compared with the prior art are the same as those of the above method for preparing a photovoltaic laminate, and will not be elaborated here.

[0098] Those skilled in the art should understand that the above embodiments are merely for clearly explaining the present invention, rather than limiting the scope of the present invention. For those skilled in the art, other changes or modifications can be made on the basis of the above disclosure, and these changes or modifications are still within the scope of the present invention.

Claims

1. A method for preparing a photovoltaic laminate, characterized in that, Including: Providing a plurality of solar cells and solder tapes, wherein solder is coated on the pads of the solar cells; Fixing the corresponding solder tapes on the pads to be electrically connected, so that the plurality of solar cells form a battery string through the solder tapes; Stacking in the order of a cover plate, a front encapsulation film, the battery string, a back encapsulation film, and a backplane to obtain a stacked component; Heating the stacked component at a first preset temperature to form a combined component; Heating the combined component at a second preset temperature to form a laminated component; The first preset temperature is higher than the melting points of the front encapsulation film and the back encapsulation film, but lower than the melting points of the solder on the solar cells and the solder on the solder tapes; The second preset temperature is higher than the melting points of the solder on the solar cells and the solder on the solder tapes.

2. The preparation method according to claim 1, characterized in that, When providing a plurality of solar cells and solder tapes, it includes: Printing the solder on the pads of the solar cells.

3. The preparation method according to claim 1, wherein When fixing the corresponding solder tapes on the pads to be electrically connected, it includes: Applying an adhesive between the solder tape and the solar cell to fix the solder tape; or, Using a positioning tape to fix the solder tape on the solar cell.

4. The preparation method according to any one of claims 1-3, characterized in that, The first preset temperature is 130°C to 150°C; Preferably, the preparation method includes: laminating the stacked component in a photovoltaic laminator at a temperature of 130°C to 150°C to form the combined component.

5. The preparation method according to claim 4, characterized in that, After laminating the stacked component including the battery string to form a combined component, the preparation method includes: Using one of a photovoltaic laminator, an oven, a flat hot press, or a laser welding machine to heat the combined component.

6. The preparation method according to claim 4, characterized in that The solar cell includes one of a back-contact solar cell, a heterojunction solar cell, or a TOPCon solar cell.

7. The preparation method according to claim 4, wherein When the solar cell includes a back-contact solar cell, before fixing the corresponding solder tapes on the pads to be electrically connected, the preparation method further includes: Covering the remaining pads except those to be electrically connected with an insulating structure among the pads under the same solder tape.

8. The preparation method according to any one of claims 1 to 3, characterized in that, When laminating the stacked component including the battery string to form a combined component, it includes: Arranging a plurality of the battery strings in an array and connecting them in series or parallel to form a battery string array, and forming a stacked component including the battery string array.

9. The preparation method according to claim 4, characterized in that The second preset temperature is 15% to 25% higher than the first preset temperature; Preferably, the second preset temperature is 5% to 20% higher than the melting points of the solder on the solar cells and the solder on the solder tapes; Preferably, the melting points of the solder on the solar cells and the solder on the solder tapes are 160°C to 180°C; Preferably, the second preset temperature is 170°C to 190°C.

10. A photovoltaic module, characterized in that, Including a photovoltaic laminate and a frame surrounding the circumferential edge of the photovoltaic laminate, and the photovoltaic laminate is prepared by the preparation method according to any one of claims 1-9.

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