Preparation method of photovoltaic module and photovoltaic module

Abstract

The invention relates to a preparation method of a photovoltaic module and the photovoltaic module. The preparation method of the photovoltaic module comprises the following steps: preheating a battery piece; pre-welding the welding strip and the battery piece to form a battery string; a carrier film is arranged on the side, provided with the welding strip, of the battery string; laminating the front cover plate, the front adhesive film, the battery string, the back adhesive film and the back plate to form a laminated piece; and laminating the laminated piece to complete welding of the welding strip and the battery piece. The welding strip and the battery piece are pre-welded, so that the relative position of the welding strip and the battery piece can be preliminarily fixed, the possibility that the welding strip shifts when a carrier film is laid is reduced, meanwhile, the possibility that a gap exists between the welding strip and a grid line of the battery piece can be reduced, and during EL detection, the possibility of blackening, strip-shaped shadow and other phenomena can be reduced; whether the battery piece has bad problems such as subfissure and fragment is conveniently judged, and the yield of the assembly is improved.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic power generation, and in particular to a method for preparing a photovoltaic module and a photovoltaic module. Background Art

[0002] The photovoltaic module includes multiple cells for converting sunlight into electrical energy. Multiple cells are connected by welding strips, and the electrical energy generated in the cells can be conducted to the busbars through the welding strips, and the busbars transmit the electrical energy out of the photovoltaic module. In the prior art, the welding strips and the cells can be connected by a laminating process. During the laminating process, the welding strips are prone to displacement, and the welding strips may not be completely aligned with the grid lines in the cell. During EL testing, the grid lines in the cell that are not aligned with the welding strips will appear black or strip-shaped shadows, resulting in the EL test being unable to determine whether there are defects such as hidden cracks or broken pieces at the locations where the black or strip-shaped shadows appear in the cell. Summary of the invention

[0003] In view of this, the present application provides a method for preparing a photovoltaic module and a photovoltaic module to solve the problem that the welding strip is easily displaced during the lamination process.

[0004] In a first aspect, an embodiment of the present application provides a method for preparing a photovoltaic module, the method comprising:

[0005] Preheat the battery cell;

[0006] Pre-welding the welding ribbon to the battery cell to form a battery string;

[0007] Disposing a carrier film on one side of the battery string where the welding strip is disposed;

[0008] Stacking the front cover plate, the front adhesive film, the battery string, the back adhesive film, and the back plate to form a stacked component;

[0009] The stack is laminated, and the welding ribbon is welded to the battery cell.

[0010] In a possible embodiment, when the battery cell is preheated, the preparation method includes:

[0011] The battery cell is heated to the preheating temperature for 20s to 30s.

[0012] In a possible embodiment, the preheating temperature is lower than the melting point of the soldering ribbon.

[0013] In a possible embodiment, when the welding ribbon is pre-welded with the battery cell to form a battery string, the preparation method includes:

[0014] The battery cell is heated to the melting point of the solder strip for a duration of less than or equal to 1 second.

[0015] In a possible embodiment, the welding strip includes a first main body portion and a second main body portion, the second main body portion is arranged around the first main body portion, the first main body portion is a conductive material, and the second main body portion is a welding material; when the welding strip is pre-welded to the battery cell, the second main body portion melts on a side close to the battery cell, and the melted portion is 20% to 50% of the second main body portion.

[0016] In a possible embodiment, after the battery cell is heated to the melting point of the solder strip for a duration less than or equal to 1 second, the preparation method includes:

[0017] The battery string is cooled to solidify the second main body so as to connect the welding ribbon and the battery sheet.

[0018] In a possible embodiment, when a carrier film is provided on a side of the battery string provided with a welding ribbon, the preparation method includes:

[0019] Laying the carrier film on the side of the battery string where the welding strip is provided;

[0020] The battery string is heated to 70° C. to 80° C. for 3 to 8 seconds to melt the carrier film.

[0021] In a possible embodiment, the size of the carrier film is greater than or equal to the size of the battery cell and smaller than the size of the battery string, and a plurality of the carrier films are provided on the battery string, and a single carrier film can cover a single battery cell in the battery string; or, the size of the carrier film is greater than or equal to the size of the battery string, and the carrier film can cover a plurality of the battery cells in the battery string.

[0022] In a possible embodiment, when the stack is laminated and the welding ribbon and the battery cell are welded, the preparation method includes:

[0023] The stack is heated to a lamination temperature, the lamination temperature being greater than or equal to the melting point of the solder ribbon.

[0024] In a second aspect, an embodiment of the present application further provides a photovoltaic module, which is prepared by any of the preparation methods described above.

[0025] The present application relates to a method for preparing a photovoltaic module and a photovoltaic module. The method for preparing a photovoltaic module includes: preheating a battery cell; pre-welding a welding tape with a battery cell to form a battery string; setting a carrier film on the side of the battery string where the welding tape is set; stacking a front cover plate, a front adhesive film, a battery string, a back adhesive film, and a back plate to form a stack; laminating the stack to complete the welding of the welding tape with the battery cell. Pre-welding the welding tape with the battery cell can preliminarily fix the relative position of the welding tape and the battery cell, reduce the possibility of displacement of the welding tape when laying the carrier film, and reduce the possibility of gaps between the welding tape and the grid lines of the battery cell. During EL testing, it can reduce the possibility of blackening, strip shadows, etc., which is convenient for judging whether the battery cell has defects such as hidden cracks and broken pieces, and improves the yield of the module. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 A flow chart of a method for preparing a photovoltaic module provided in an embodiment of the present application;

[0028] Figure 2 A schematic diagram of the structure of laying a welding ribbon on a solar cell in the photovoltaic module preparation method provided in an embodiment of the present application;

[0029] Figure 3 A schematic diagram of the structure of the photovoltaic module preparation method provided in the embodiment of the present application after the welding strip is pre-welded;

[0030] Figure 4 A schematic diagram of the structure after laying a carrier film in the photovoltaic module preparation method provided in an embodiment of the present application;

[0031] Figure 5 A schematic diagram of the structure after the carrier film is melted in the photovoltaic module preparation method provided in an embodiment of the present application;

[0032] Figure 6 A schematic diagram of the structure of a stacked component provided in an embodiment of the present application;

[0033] Figure 7 This is a schematic diagram of the structure of the laminated components after lamination in the photovoltaic module preparation method provided in an embodiment of the present application.

[0034] Reference numerals:

[0035] 1-Battery cell;

[0036] 2-welding strip;

[0037] 21- a first main body;

[0038] 22- second main body;

[0039] 3-Carrier membrane;

[0040] 4-Front cover;

[0041] 5-front adhesive film;

[0042] 6-back film;

[0043] 7- Back panel. DETAILED DESCRIPTION

[0044] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0045] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0046] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0047] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0048] For busbar-free cells, there is no busbar on the surface of the cell 1. After welding multiple cells 1, the welding ribbon 2 directly connects the original busbar to the fine grid instead of the original busbar, which can reduce the consumption of silver paste and the production cost of the cell 1. Busbar-free cells can reduce the shading area of ​​the grid line in the cell 1 and reduce the transmission loss of the fine grid, thereby increasing the total power of the component. At the same time, the increase in the fine grid contact points reduces the risk of hidden cracks in thin silicon wafers and improves the yield and reliability.

[0049] The preparation method of the main-grid-free assembly in the related art is: laying the welding ribbon 2 on the battery cell 1, and then using the carrier film 3 to fix the welding ribbon 2 on the battery cell 1, so that multiple battery cells 1 form a battery string, and finally stacking and laminating with the back plate 7, the adhesive film and the photovoltaic glass to form a main-grid-free photovoltaic assembly. Before the welding ribbon 2 is fixed to the battery cell 1 by the carrier film 3, the welding ribbon 2 is prone to misalignment, and the carrier film 3 cannot ensure that the welding ribbon 2 is completely attached to the grid line. There will be gaps between the welding ribbon 2 and part of the grid line. During EL testing, the position where the gap exists will appear black, strip shadows, etc. It is difficult to judge whether the battery cell 1 at the black or strip shadow has defects such as hidden cracks and broken pieces, resulting in the inability to ensure the yield of the assembly.

[0050] The embodiment of the present application provides a method for preparing a photovoltaic module to improve the welding effect between the welding ribbon 2 and the battery cell 1. The above preparation method does not limit the type of the battery cell 1. The types of the battery cell 1 include but are not limited to passivated emitter rear cell (Passivated Emitter Rear Cell, PERC), oxide passivated contact cell (Tunnel Oxide Passivated Contact, TOPCon), intrinsic thin film heterojunction cell (Heterojunction with Intrinsic Thin-film, HJT), interdigitated back contact cell (Interdigitated Back Contact, IBC), perovskite cell, etc.

[0051] For PERC cells, along the thickness direction, PERC cells include front surface metal silver electrode, front surface silicon nitride passivation layer, phosphorus layer emitter, P-type base silicon layer, local aluminum back field, metal aluminum back electrode, back passivation layer (Al2O3 / SiNx). PERC cells use a passivation film to passivate the back, replacing the full aluminum back field, enhancing the internal back reflection of light in the silicon base, reducing the recombination rate on the back, and increasing the efficiency of the cell by 0.5%-1%.

[0052] For TOPCon cells, along the thickness direction, TOPCon cells include metal silver electrodes, front surface silicon nitride passivation layers, boron-doped emitters, N-type base silicon layers, diffused doping layers, ultra-thin silicon oxide, doped polysilicon, silicon nitride, and metal silver electrodes. The back of the cell is composed of a layer of ultra-thin silicon oxide (1nm to 2nm) and a layer of phosphorus-doped microcrystalline amorphous mixed Si film, which together form a passivation contact structure. This structure can block the recombination of minority carrier holes and increase the open circuit voltage and short circuit current of the cell. The ultra-thin oxide layer allows majority electrons to tunnel into the polysilicon layer while blocking the recombination of minority carrier holes. The good passivation effect of ultra-thin silicon oxide and heavily doped silicon film causes the energy band on the silicon wafer surface to bend, thereby forming a field passivation effect, greatly increasing the probability of electron tunneling, reducing contact resistance, and increasing the open circuit voltage and short circuit current of the cell, thereby improving the cell conversion efficiency.

[0053] For HJT cells, along the thickness direction, the HJT cells include a front low-temperature silver electrode, a front conductive film, an N-type amorphous silicon film, an intrinsic amorphous silicon film, an N-type base silicon layer, an intrinsic amorphous silicon film, a P-type amorphous silicon film, a back conductive film, and a back low-temperature silver electrode.

[0054] For IBC cells, along the thickness direction, IBC cells include silicon nitride anti-layer, N+ front surface field, N-type base silicon layer, P+ emitter, N+ back field, aluminum oxide passivation layer, silicon nitride anti-reflection layer, and metal silver electrode. IBC cells use ion implantation technology to obtain P and N regions with good uniformity and precisely controllable junction depth. There is no grid line blocking on the front of the cell, which can eliminate the shading current loss of the metal electrode and achieve the maximum utilization of incident photons. The short-circuit current can be increased by about 7% compared with conventional solar cells; due to the back contact structure, there is no need to consider the grid line blocking problem, and the grid line ratio can be appropriately widened, thereby reducing the series resistance and having a high fill factor; the surface passivation and surface light trapping structure can be optimized to obtain a lower front surface recombination rate and surface reflection.

[0055] For perovskite cells, along the thickness direction, the perovskite cell includes substrate material, conductive film, electron transport layer (titanium dioxide), perovskite absorption layer (hole transport layer), and metal cathode. Perovskite materials have a high light absorption coefficient and a long carrier diffusion distance. After the photons absorbed by the perovskite material are converted into electrons, they are easily collected by the electrode with low loss, so they can generate higher photoelectric voltage and current, making perovskite show higher photoelectric conversion efficiency.

[0056] like Figures 1 to 7 As shown, the preparation method provided in the embodiment of the present application includes:

[0057] S1, preheating battery cell 1;

[0058] S2, pre-welding the welding ribbon 2 and the battery cell 1 to form a battery string;

[0059] S3, a carrier film 3 is arranged on one side of the battery string where the welding strip 2 is arranged;

[0060] S4, stacking the front cover plate 4, the front adhesive film 5, the battery string, the back adhesive film 6, and the back plate 7 to form a stacked component;

[0061] S5 , laminating the stacked parts to complete the welding of the welding ribbon 2 and the battery cell 1 .

[0062] After the welding tape 2 is laid on the battery cell 1, the welding tape 2 is pre-welded to the battery cell 1, which can initially fix the relative position of the welding tape 2 and the battery cell 1, reducing the possibility of displacement of the welding tape 2 when laying the carrier film 3. During pre-welding, the welding tape 2 can also form a certain alloy with the grid line of the battery cell, reducing the possibility of gaps between the welding tape 2 and the grid line of the battery cell 1. During EL testing, the possibility of blackening, strip shadows and other phenomena can be reduced, which is convenient for judging whether the battery cell 1 has defects such as hidden cracks and broken pieces, and improves the yield of the component. Laying the carrier film 3 on the side of the battery cell 1 where the welding tape 2 is provided can further limit the relative position of the welding tape 2 and the battery cell 1, and reduce the possibility of displacement of the welding tape 2 during the stacking and lamination process.

[0063] like Figure 2 As shown, the soldering ribbon 2 includes a first main body portion 21 and a second main body portion 22 , wherein the first main body portion 21 is a conductive material, the second main body portion 22 is a soldering material, and the second main body portion 22 is disposed around the first main body portion 21 .

[0064] When the welding ribbon 2 is welded to the battery cell 1, the second main body 22 melts, and after solidification, the welding ribbon 2 is fixed to the battery cell 1 to connect multiple battery cells 1. The welding ribbon 2 can also electrically connect multiple battery cells 1. The electric energy generated in the battery cell 1 is transmitted to the bus bar in the photovoltaic module through the welding ribbon 2, and then transmitted out of the photovoltaic module through the bus bar. The grid line material on the battery cell 1 is silver, and the second main body 22 can be a tin layer. After the tin layer is heated and melted, it can be alloyed with silver, reducing the resistance between the welding ribbon 2 and the battery cell 1, and facilitating the transmission of the current generated in the battery cell 1 to the second main body 22 of the welding ribbon 2. The current generated in the battery cell 1 will be conducted to the first main body 21 through the second main body 22. The first main body 21 can be a copper core, and the resistance of the copper core is relatively small. When the electric energy is transmitted from the welding ribbon 2 to the bus bar, the loss of the electric energy generated by the welding ribbon 2 to the battery cell 1 is reduced.

[0065] When preheating the battery cell 1, the preparation method includes:

[0066] S11, heating the battery cell 1 to the preheating temperature for 20s to 30s

[0067] When the soldering ribbon 2 and the battery cell 1 are welded, a relatively high temperature is required. The battery cell 1 is preheated for 20s to 30s to allow the battery cell 1 to adapt to the preheating temperature. When the soldering ribbon 2 and the battery cell 1 are welded, the difference between the temperature of the battery cell 1 and the welding temperature is reduced, thereby reducing the possibility of thermal stress in the battery cell 1 due to large temperature changes, thereby reducing the risk of damage to the battery cell 1 caused by welding.

[0068] The heating element can be set in the platform for transporting or placing the battery cell 1, and the battery cell 1 can be preheated by placing it on the platform surface; the heating element can also be a heating lamp tube set above the platform. After the battery cell 1 is placed on the platform surface, the heating lamp tube is turned on to heat the battery cell 1. The battery cell 1 can also be preheated by other means.

[0069] In a possible embodiment, the preheating temperature is lower than the melting point of the soldering ribbon 2 .

[0070] Taking the second main body 22 of the soldering tape 2 as a tin layer as an example, the lower limit of the melting point of the tin layer is between 150°C and 170°C. After the battery cell 1 is preheated, the soldering tape 2 needs to be laid on the side of the battery cell 1 with the grid line. At this time, the second main body 22 of the soldering tape 2 is in contact with the battery cell 1. The preheating temperature of the battery cell 1 can be 135°C, which is lower than the melting point of the second main body 22 in the soldering tape 2. When the second main body 22 in the soldering tape 2 is in contact with the battery cell 1, the possibility of the second main body 22 melting can be reduced, which facilitates the laying of the soldering tape 2 to the preset position. If the second main body 22 of the soldering tape 2 is other welding materials, the heating temperature of the battery cell 1 during preheating needs to be determined according to the specific material of the second main body 22, and the heating temperature should be lower than the melting point of the second main body 22.

[0071] like Figure 3 As shown, when the welding ribbon 2 is pre-welded with the battery cell 1 to form a battery string, the preparation method includes:

[0072] S21, heating the battery cell 1 to the melting point of the soldering ribbon 2, with the duration being less than or equal to 1 second.

[0073] Taking the second main body 22 of the soldering tape 2 as a tin layer as an example, the lower limit of the melting point of the tin layer is between 150°C and 170°C. After the soldering tape 2 is laid to the preset position, the heating temperature can be between 150°C and 170°C, reaching the lower limit of the melting point of the second main body 22 in the soldering tape 2, so that the second main body 22 begins to melt, but the melting rate is relatively low, and the heating time is less than or equal to 1s to control the quality of the melted part of the second main body 22. The melted part enables the soldering tape 2 to be pre-welded with the battery cell 1, and can achieve a certain degree of alloying with the grid line of the battery cell 1. If the heating temperature is less than 150°C, the second main body 22 of the welding ribbon 2 cannot be melted and cannot be welded to the battery cell 1. If the heating temperature is greater than 170°C, the second main body 22 of the welding ribbon 2 melts faster, and it is difficult to control the melting quality of the second main body 22, resulting in the difficulty in controlling the degree of alloying between the welding ribbon 2 and the grid line during pre-welding. After lamination, the welding ribbon 2 will continue to melt and further alloy with the grid line. Excessive alloying will cause the grid line to break. Therefore, the heating temperature can be 150°C, 160°C, 170°C, etc. If the second main body 22 of the welding ribbon 2 is other welding materials, the heating temperature during pre-welding needs to be determined according to the specific material of the second main body 22.

[0074] The side of the second main body 22 that contacts the battery cell 1 partially melts to pre-weld the welding ribbon 2 to the battery cell 1, which can reduce the possibility of a gap between the welding ribbon 2 and the grid lines of the battery cell 1. In EL detection, it can reduce the occurrence of blackening and stripe shadows, which makes it impossible to determine whether the battery cell 1 at the blackening and stripe shadows has defects such as hidden cracks and broken pieces, which is beneficial to improving the yield rate of photovoltaic modules after EL detection.

[0075] After heating the battery cell 1 to the melting point of the solder strip 2 for a duration less than or equal to 1 second, the preparation method comprises:

[0076] S22 , cooling the battery cell 1 to solidify the second main body 22 , so as to connect the welding ribbon 2 and the battery cell 1 .

[0077] After the second main body 22 in the soldering ribbon 2 partially melts, the battery cell 1 is cooled to below the melting point of the second main body 22, and the second main body 22 is solidified, so that the soldering ribbon 2 can be fixed to the battery cell 1 through the second main body 22, reducing the possibility of displacement of the soldering ribbon 2 during the laying of the carrier film 3 and the stacking process.

[0078] After multiple battery cells 1 are welded into a battery string through the welding ribbon 2, it is necessary to lay a carrier film 3 on the side of the battery cell 1 where the welding ribbon 2 is provided. The melting point of the carrier film 3 is lower than the melting point of the second main body 22 in the welding ribbon 2. When the second main body 22 is solidified, the temperature of the battery cell 1 is reduced to below the melting point of the carrier film 3. When laying the carrier film 3, the possibility of the carrier film 3 melting due to contact with the welding ribbon 2 is reduced, which facilitates the laying of the carrier film 3.

[0079] like Figure 3 As shown, in a possible embodiment, when the welding ribbon 2 is pre-welded to the battery cell 1 , a side of the second main body 22 close to the battery cell 1 melts, and the melted portion accounts for 20% to 50% of the second main body 22 .

[0080] The soldering ribbon 2 is pre-welded with the battery cell 1 to reduce the possibility of the soldering ribbon 2 shifting. If less than 20% of the second main body 22 melts during pre-welding, the contact area between the second main body 22 and the battery cell 1 is small. After solidification, the stability of the soldering ribbon 2 after pre-welding is reduced, and the soldering ribbon 2 is prone to shifting during the laying of the carrier film 3. The temperature of the lamination process is higher than the melting point of the second main body 22, which will cause the second main body 22 to further melt. The material of the second main body 22 is tin, and the material of the grid line is silver. When tin and silver are alloyed, Silver will be consumed in due course. If the melted portion of the second main body 22 during pre-welding is greater than 50%, the second main body 22 will melt too much after lamination and will be alloyed to a greater extent with the grid line, resulting in excessive silver consumption. During lamination, the alloying degree between the welding ribbon and the grid line will continue to increase, which may easily lead to grid line breakage. Therefore, during pre-welding, the melted portion of the second part is 20%, 35%, 50%, etc., so that the position of the welding ribbon 2 on the battery cell 1 after pre-welding is more stable, and the possibility of grid line breakage on the battery cell 1 can be reduced after lamination.

[0081] like Figure 4 and Figure 5 As shown, in a possible embodiment, when a carrier film 3 is provided on one side of a battery string provided with a welding ribbon 2, the preparation method includes:

[0082] S31, laying the carrier film 3 on the side of the battery cell 1 where the welding ribbon 2 is provided;

[0083] S32, heating the battery string to 70° C. to 80° C. for 3 to 8 seconds to melt the carrier film 3;

[0084] S33, cooling the temperature of the battery string to below the melting point of the carrier film 3, so that the carrier film 3 is solidified.

[0085] The carrier film 3 is laid on the side of the cell 1 where the welding strip 2 is provided, so that the welding strip 2 is located between the carrier film 3 and the cell 1. After the carrier film 3 melts, it is bonded to the cell 1, which can limit the relative position between the welding strip 2 and the cell 1, further reducing the possibility of the welding strip 2 shifting, which is beneficial to improving the reliability of the photovoltaic module. The battery string is heated to 70°C to 80°C to melt the carrier film 3 for 3s to 8s. The melted carrier film 3 contacts the cell 1, and the thickness of the melted carrier film 3 is greater than the thickness of the welding strip 2, so that the carrier film 3 can wrap the welding strip 2. After the carrier film 3 solidifies, it is bonded to the cell 1, so that the welding strip 2 is fixed between the cell 1 and the carrier film 3, further improving the stability of the welding strip 2.

[0086] In a possible embodiment, the size of the carrier film is greater than or equal to the size of the battery cell 1, but smaller than the size of the battery string. A single carrier film 3 can cover one side of a single battery cell 1 provided with a welding strip 2. A plurality of carrier films 3 are provided on the battery string so that each battery cell 1 can be covered with a carrier film 3.

[0087] The carrier film 3 is laid on the side of the cell 1 provided with the welding ribbon 2. The size of the carrier film 3 is greater than or equal to the size of the cell 1, so that the carrier film 3 can completely cover the cell 1 after melting to limit the relative position between the welding ribbon 2 and the cell 1. A single carrier film 3 is correspondingly provided on the side of a single cell 1 provided with the welding ribbon 2, which can reduce the possibility of bubbles between the carrier film 3 and the cell 1.

[0088] In a possible embodiment, the size of the carrier film 3 is greater than or equal to the size of the battery string, and a single carrier film 3 is laid on one side of the battery string where the welding ribbon 2 is provided to cover multiple battery cells 1 in the battery string.

[0089] After the battery cell 1 and the welding ribbon 2 are pre-welded to form a battery string, a carrier film 3 is laid. The size of the carrier film 3 is greater than or equal to the size of the battery string. A single carrier film 3 is laid on one side of the battery string where the welding ribbon 2 is provided to cover multiple battery cells 1 in the battery string, which simplifies the process of laying the carrier film 3 and is beneficial to improving the production efficiency of photovoltaic modules.

[0090] Different types of battery cells 1 have different grid lines, and the positions of the soldering tapes 2 will also change accordingly. Take TOPCon batteries and BC batteries as examples: the grid lines of TOPCon batteries are located on the front and back of the battery cells 1, respectively. When multiple TOPCon battery cells 1 are connected in series, soldering tapes 2 are required to connect the grid lines on the front of one battery cell 1 with the grid lines on the back of another battery cell 1. Therefore, soldering tapes 2 are provided on both the front and back of the battery cell 1. After forming a battery string, carrier films 3 need to be laid on both the front and back of the battery cell 1 to reduce the possibility of displacement of the soldering tapes 2 on the front and back of the battery cell 1. Figures 2 to 7 As shown, the P / N junction, substrate and emitter contact electrodes of the BC battery are made in an interdigitated shape on the back of the battery, so that the grid lines of the BC battery are all located on the back of the battery. When multiple BC battery cells 1 are connected in series, the welding strips 2 are all set on the back of the battery cells 1. After the battery string is formed, it is only necessary to lay a carrier film 3 on the back of the battery cell 1 to reduce the possibility of displacement of the welding strip 2 on the back of the battery cell 1, thereby reducing the difficulty of the process of laying the carrier film 3 and improving the production efficiency of photovoltaic modules.

[0091] like Figure 6 and Figure 7 As shown, in a possible embodiment, when laminating the stacked parts and welding the welding ribbon 2 and the battery cell 1, the preparation method includes:

[0092] S51 , heating the laminate to a lamination temperature, wherein the lamination temperature is greater than or equal to the melting point of the solder tape 2 .

[0093] Before lamination, the second main body 22 in the welding ribbon 2 partially melts and forms a certain alloy with the grid line in the battery cell 1. At this time, the stability of the welding ribbon 2 and the electrical conductivity between the welding ribbon 2 and the grid line are both poor. When the stack is laminated, the heating temperature is higher than the melting point of the second main body 22, so that the second main body 22 in the welding ribbon 2 is completely melted, which can improve the welding strength between the welding ribbon 2 and the battery cell 1, and can also improve the degree of alloying between the second main body 22 and the grid line, thereby improving the electrical conductivity between the battery cell 1 and the grid line, and thus can improve the power generation effect of the photovoltaic module.

[0094] The embodiment of the present application also provides a photovoltaic module, which is prepared by the above-mentioned preparation method, and can reduce the possibility of misalignment of the welding ribbon 2 or the existence of a gap between the welding ribbon 2 and the grid line of the battery cell 1. During EL detection, it can reduce the possibility of blackening, strip shadows and other phenomena, which is convenient for judging whether the battery cell 1 has hidden cracks, breakage and other defects, thereby improving the yield of the module.

[0095] The present application relates to a method for preparing a photovoltaic module and a photovoltaic module. The method for preparing a photovoltaic module includes: preheating a cell 1; pre-welding a welding tape 2 with the cell 1 to form a cell string; arranging a carrier film 3 on the side of the cell string where the welding tape 2 is arranged; stacking a front cover plate 4, a front adhesive film 5, a cell string, a back adhesive film 6, and a back plate 7 to form a stack; and laminating the stack to complete the welding of the welding tape 2 with the cell 1. Pre-welding the welding tape 2 with the cell 1 can preliminarily fix the relative position of the welding tape 2 and the cell 1, reduce the possibility of displacement of the welding tape 2 when laying the carrier film 3, and reduce the possibility of gaps between the welding tape 2 and the grid lines of the cell 1. During EL testing, the possibility of blackening, strip shadows, etc. can be reduced, which is convenient for judging whether the cell 1 has defects such as hidden cracks and broken pieces, thereby improving the yield of the module.

Claims

1. A method for preparing a photovoltaic module, characterized in that: The preparation method comprises: Preheat the battery cell; Pre-welding the welding ribbon to the battery cell to form a battery string; Disposing a carrier film on one side of the battery string where the welding strip is disposed; Stacking the front cover plate, the front adhesive film, the battery string, the back adhesive film, and the back plate to form a stacked component; The stack is laminated, and the welding ribbon is welded to the battery cell.

2. The method for preparing a photovoltaic module according to claim 1, characterized in that: When the battery cell is preheated, the preparation method includes: The battery cell is heated to the preheating temperature for 20s to 30s.

3. The method for preparing a photovoltaic module according to claim 1, characterized in that: The preheating temperature is lower than the melting point of the soldering ribbon.

4. The method for preparing a photovoltaic module according to claim 1, characterized in that: When the welding ribbon is pre-welded with the battery cell to form a battery string, the preparation method includes: The battery cell is heated to the melting point of the solder strip for a duration of less than or equal to 1 second.

5. The method for preparing a photovoltaic module according to claim 4, characterized in that: The welding strip includes a first main body portion and a second main body portion, the second main body portion is arranged around the first main body portion, the first main body portion is a conductive material, and the second main body portion is a welding material; when the welding strip is pre-welded to the battery cell, the second main body portion melts on a side close to the battery cell, and the melted portion is 20% to 50% of the second main body portion.

6. The method for preparing a photovoltaic module according to claim 5, characterized in that: After the battery cell is heated to the melting point of the solder strip for a duration of less than or equal to 1 second, the preparation method comprises: The battery string is cooled to solidify the second main body so as to connect the welding ribbon and the battery sheet.

7. The method for preparing a photovoltaic module according to claim 1, characterized in that: When a carrier film is provided on a side of the battery string provided with a welding strip, the preparation method comprises: Laying the carrier film on the side of the battery string where the welding strip is provided; The battery string is heated to 70° C. to 80° C. for 3 to 8 seconds to melt the carrier film.

8. The method for preparing a photovoltaic module according to claim 1, characterized in that: The size of the carrier film is greater than or equal to the size of the battery cell and smaller than the size of the battery string. A plurality of the carrier films are arranged on the battery string, and a single carrier film can cover a single battery cell in the battery string; or, the size of the carrier film is greater than or equal to the size of the battery string, and the carrier film can cover a plurality of the battery cells in the battery string.

9. The method for preparing a photovoltaic module according to claim 1, characterized in that: When the stack is laminated and the welding ribbon is welded to the battery cell, the preparation method includes: The stack is heated to a lamination temperature, the lamination temperature being greater than or equal to the melting point of the solder ribbon.

10. A photovoltaic module, characterized in that: The photovoltaic module is prepared by the preparation method according to any one of claims 1 to 9.

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