A photovoltaic cell string and method of fabrication thereof

Abstract

This invention discloses a photovoltaic cell string and its manufacturing method, relating to the field of photovoltaic module technology. The photovoltaic cell string includes multiple cells and multiple solder strips. The edges of adjacent cells are connected in a shingled manner, and a support portion and an adhesive portion are provided at the overlap of adjacent cells. The support portion is made of a solid adhesive, and the adhesive portion is made of a plastic adhesive. The support portion is cured before the adjacent cells are electrically connected; the adhesive portion is cured before the adjacent cells are electrically connected, and the temperature at which it transitions from a highly elastic state to a viscoelastic state is higher than the lamination temperature of the photovoltaic module but lower than the welding temperature for the electrical connection of the adjacent cells. This photovoltaic cell string can prevent microcracks in the overlapping areas of the cells during the stringing and lamination process, and it can also prevent overall or partial cell displacement during the stringing and lamination process.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module technology, and in particular to a photovoltaic cell string and its manufacturing method. Background Technology

[0002] In existing technologies, reducing the spacing between adjacent cells in a cell string is one of the most effective ways to further improve the packaging density of photovoltaic modules, increase the power generation per unit area of ​​photovoltaic modules, and thus improve the photoelectric conversion efficiency of photovoltaic modules. However, during the process from string welding to lamination, the overlapping area of ​​adjacent cells is prone to overall or local cell displacement or microcracks in the overlapping area. Summary of the Invention

[0003] In view of this, the present invention provides a photovoltaic cell string and a method for manufacturing the same, in order to solve the technical problem that overall or local cell displacement or microcracks in the overlapping area of ​​cells are prone to occur during the process from string welding to lamination at the overlap of two adjacent cells.

[0004] To solve the above-mentioned technical problems, according to one aspect of the present invention, a photovoltaic cell string is provided, comprising multiple cells and multiple solder strips, wherein the front main grid of one of two adjacent cells is electrically connected to the back main grid of the other cell via solder strips. The edges of two adjacent solar cells are connected in a shingled manner, and the overlapping part of two adjacent solar cells is provided with a support and an adhesive part; The supporting part is made of solid adhesive, and the bonding part is made of plastic adhesive; The support portion is cured before the electrical connection of two adjacent solar cells; The adhesive portion is cured before the electrical connection of two adjacent cells, and the temperature at which it transitions from a highly elastic state to a viscoelastic state is higher than the lamination temperature of the photovoltaic module and lower than the welding temperature of the electrical connection between two adjacent cells.

[0005] Optionally, the support portion and the adhesive portion are provided alternately.

[0006] Optionally, the solder strip passes through the adhesive portion, and the support portion is located between two adjacent solder strips.

[0007] Optionally, the support portion and the adhesive portion overlap, and at least a portion of the support portion is embedded in the adhesive portion.

[0008] Optionally, the support portion and the adhesive portion are located between two adjacent weld strips.

[0009] In another aspect, the present invention also provides a method for manufacturing a photovoltaic cell string, comprising: Step A: Apply solid adhesive and plastic adhesive along the edge of the overlapping area of ​​two adjacent battery cells and cure them to form a support and adhesive part at the overlapping area of ​​two adjacent battery cells. Step B: Connect the edges of the two solar cells in a shingled manner, so that the support and adhesive parts are located at the overlap of the two solar cells. Weld the solder strip to the front main grid of one solar cell and the back main grid of the other solar cell to electrically connect the two adjacent solar cells. The temperature at which the adhesive layer transitions from a highly elastic state to a viscoelastic state is higher than the lamination temperature of the photovoltaic module but lower than the welding temperature of the electrical connection between two adjacent cells.

[0010] Optionally, in step A, the height of the cured adhesive portion is greater than the height of the cured support portion along the direction of the cell thickness.

[0011] Optionally, step A includes: Solid adhesive and plastic adhesive are applied along the same edge of the same cell in two adjacent cells and then cured to form a support and adhesive portion at the edge of the cell. or, A solid adhesive is applied along the first edge of the front side of one solar cell and cured to form a support portion at the edge of the solar cell; a plastic adhesive is applied along the second edge of the back side of another solar cell and cured to form an adhesive portion at the edge of the solar cell. or, A solid adhesive is applied along the second edge of the front side of one solar cell and cured to form a support portion at the edge of the solar cell; a plastic adhesive is applied along the first edge of the back side of another solar cell and cured to form an adhesive portion at the edge of the solar cell.

[0012] Optionally, the support portion and the adhesive portion are arranged alternately. And / or, The solder strip passes through the adhesive portion, and the support portion is located between two adjacent solder strips.

[0013] Optionally, the support portion and the adhesive portion overlap, and at least a portion of the support portion is embedded within the adhesive portion. And / or, The support and adhesive portions are located between two adjacent weld strips.

[0014] The technical solution of the present invention has the following advantages or beneficial effects: In the embodiments of the present invention, by providing a support part and an adhesive part at the overlapping part of two adjacent battery cells, the cured support part plays the role of supporting the two adjacent battery cells during the stringing and lamination processes. Moreover, during the stringing process, the cured adhesive part changes from a highly elastic state to a viscoelastic state. At the same time, under the pressure of the tooling, the softened adhesive part forms a good contact area with the battery cell, tightly bonding the overlapping part of the two adjacent battery cells together. After the stringing is completed, the viscoelastic adhesive part changes back to a highly elastic state, so that the adhesive part firmly bonds the overlapping part of the two adjacent battery cells together. Therefore, the adhesive part can prevent the overall or partial displacement of battery cells during the stringing and lamination process. By combining the support and bonding parts, the problem of microcracks in the overlapping areas of the cells can be prevented due to the pressure on the solder strips during the process of string welding to lamination. It can also prevent the overall or partial displacement of the cells during the process of string welding to lamination. This results in an increase in the packaging density of photovoltaic modules and an increase in power generation per unit area. Moreover, the process is simple and has a high degree of compatibility and automation. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a structure according to an embodiment of the present invention, in which a support portion and an adhesive portion are provided at the edge of the overlapping area of ​​two adjacent battery cells; Figure 2 This is a schematic diagram of a structure in which a support portion and an adhesive portion are provided at the edge of the overlapping area of ​​two adjacent battery cells according to another embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present invention; Figure 4a , Figure 4b , Figure 4c and Figure 4d This is a cross-sectional view of the overlapping area of ​​two adjacent battery cells according to an embodiment of the present invention; Figure 5a and Figure 5b This is a schematic diagram of a structure in which a support portion and an adhesive portion are provided on the same edge of the same battery cell according to an embodiment of the present invention; Figure 6a and Figure 6bThis is a schematic diagram of welding two adjacent battery cells when a support portion and an adhesive portion are provided on the same edge of the same battery cell, according to an embodiment of the present invention. Figure 7a and Figure 7b This is a schematic diagram of welding two adjacent battery cells when a support portion and an adhesive portion are provided on the same edge of the same battery cell, according to another embodiment of the present invention. Figure 8a and Figure 8b This is a schematic diagram of welding two adjacent battery cells when a support portion and an adhesive portion are provided on the same edge of the same battery cell, according to another embodiment of the present invention. Figure 9a , Figure 9b and Figure 9c This is a schematic diagram of welding two adjacent battery cells when support portions and adhesive portions are provided at the edges of different battery cells according to an embodiment of the present invention. Figure 10a , Figure 10b and Figure 10c This is a schematic diagram of welding two adjacent battery cells when support portions and adhesive portions are provided at the edges of different battery cells according to an embodiment of the present invention. Figure 11 This is a schematic diagram showing the height of the support portion and adhesive portion at the edge of the battery cell according to an embodiment of the present invention.

[0017] The attached figures are labeled as follows: 10-Battery cell; 101-First edge of the front side; 102-Second edge of the front side; 103-First edge of the back side; 104-Second edge of the back side; 105-Front main grid; 106-Back main grid; 20-Welding strip; 30-Support part; 40-Adhesive part. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0019] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "circumferential," and "radial," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] This invention proposes to provide a support portion and an adhesive portion at the overlapping area of ​​two adjacent solar cells. The cured support portion supports the two adjacent solar cells, while the cured adhesive portion bonds them together. During the stringing process, the cured adhesive portion transforms from a highly elastic state to a viscoelastic state. Simultaneously, under the pressure of the tooling, the softened adhesive portion forms a good contact area with the solar cells, tightly bonding the overlapping area of ​​the two adjacent solar cells together. After stringing, the viscoelastic adhesive portion transforms back to a highly elastic state, firmly bonding the overlapping area of ​​the two adjacent solar cells together. Therefore, the adhesive portion can prevent overall or partial displacement of solar cells during the stringing and lamination process. In this way, the cooperation of the support portion and the adhesive portion can prevent microcracks in the overlapping area of ​​the solar cells during stringing and lamination, as well as overall or partial displacement of the solar cells during the stringing and lamination process. This achieves increased photovoltaic module packaging density and increased power generation per unit area. Furthermore, the process is simple and has a high degree of compatibility and automation.

[0022] The specific structure and manufacturing method of the photovoltaic cell string provided in the embodiments of the present invention will be described in detail below.

[0023] like Figure 1 and Figure 2As shown, the photovoltaic cell string includes multiple cells 10 and multiple solder ribbons 20. The front main busbar 105 of one cell 10 and the back main busbar 106 of another cell 10 are electrically connected by solder ribbons 20. Furthermore, the edges of two adjacent cells 10 are connected in a shingled manner, and a support portion 30 and an adhesive portion 40 are provided at the overlapping part of two adjacent cells 10. It should be noted that the multiple cells 10 are arranged sequentially and the edges of two adjacent cells 10 are connected in a shingled manner. For each cell 10, the front main busbar 105 of the cell 10 is welded to the back main busbar 106 of the cell 10 on one side of it by solder ribbons 20, and the back main busbar 106 of the cell 10 is welded to the front main busbar 105 of the cell 10 on the other side of it by solder ribbons 20. Thus, multiple cells 10 are welded into a photovoltaic cell string by solder ribbons 20.

[0024] In an embodiment of the present invention, a support portion 30 and an adhesive portion 40 are provided at the overlapping area of ​​two adjacent solar cells 10. The support portion 30 serves to support the two adjacent solar cells 10, and the adhesive portion 40 serves to bond the two adjacent solar cells 10. This can prevent microcracks in the overlapping area of ​​the solar cells during the process of string welding to lamination, and can also prevent overall or partial displacement of the solar cells during the process of string welding to lamination, thereby increasing the packaging density of the photovoltaic module and the power generation per unit area.

[0025] Understandably, the support portion 30 does not have an adhesive function. To prevent the support portion 30 from shifting, it can be fixed to the edge of either of two adjacent battery cells 10 and abut against the edge of the other battery cell 10. Figure 3 As shown, the battery cell 10 has a first edge 101 on the front side, a second edge 102 on the front side, a first edge 103 on the back side, and a second edge 104 on the back side, wherein the first edge and the second edge are located on opposite sides of the battery cell 10. Figure 1 As shown, the support 30 can be fixed to the first edge 101 on the front side of the battery cell 10, and the overlapping area of ​​two adjacent battery cells 10 is located at this edge. Figure 2 As shown, the support 30 can also be fixed to the second edge 104 on the back of the battery cell 10, where the overlap of two adjacent battery cells 10 is located.

[0026] In some embodiments of the present invention, the support portion 30 is cured before the electrical connection of two adjacent battery cells 10. The support portion 30 can be made of a solid adhesive, also known as a solid resin adhesive, which is a synthetic resin adhesive made from a solid resin containing reactive groups. Its core feature is that an irreversible cross-linking reaction is initiated by heating, UV irradiation, or the addition of a curing agent, transforming it from a liquid or plastic state into an insoluble and infusible three-dimensional polymer network structure, thereby achieving a strong bonding effect. Once this cross-linking reaction occurs, it cannot be reversed. The solid adhesive can be selected from one or more of epoxy resin adhesives, phenolic resin adhesives, polyurethane adhesives, silicone adhesives, urea-formaldehyde resin adhesives, polyimide adhesives, and unsaturated polyester adhesives. Therefore, the cured support portion 30 can support two adjacent battery cells 10 in subsequent welding and lamination processes, but it does not have the function of bonding two adjacent battery cells 10.

[0027] In some embodiments of the present invention, the adhesive portion 40 can be made of a plastic adhesive, also known as a plastic resin adhesive, which is a synthetic resin adhesive made from a linear polymeric plastic resin as a base material. Its core characteristic is that no irreversible cross-linking reaction occurs during the curing process; instead, the transition from a liquid or molten state to a solid state is achieved solely through physical means such as solvent evaporation, melt cooling, or emulsion coagulation, thereby achieving the bonding effect. Furthermore, after curing, it can be softened again by heat and hardened again by cooling, possessing the characteristic of repeated bonding. The plastic adhesive can be selected from one or more of polyvinyl acetate adhesive, polyacrylate adhesive, EVA hot melt adhesive, polyamide adhesive, polyvinyl alcohol acetal adhesive, chlorinated polyvinyl resin adhesive, and polyurethane hot melt adhesive. Therefore, the adhesive portion 40, after curing, can be softened again by heat and hardened again by cooling, serving to bond two adjacent battery cells 10.

[0028] It should be noted that both the elastic and viscoelastic states are physical states of thermoplastic adhesives. The core of their transition is a temperature-induced reversible physical change, without chemical cross-linking reactions. The elastic state is the state of thermoplastic adhesives above the glass transition temperature and below the viscous flow temperature, possessing both elasticity and slight plasticity, and can quickly return to its original shape after being subjected to force. The viscoelastic state is a transitional state between the elastic and viscous flow states, possessing both viscosity and elasticity, and is the intermediate process in the transition from the elastic to the viscous flow state. The core factor triggering these two state transitions is temperature increase. When the elastic material is heated to a specific temperature (close to the viscous flow temperature), the molecular chain mobility increases, elasticity decreases, viscosity increases, and it gradually transitions from the elastic state to the viscoelastic state. After cooling, it can reversibly return to the elastic state, and the transition is completely reversible. When heated, the plastic adhesive changes from a highly elastic state to a viscoelastic state. At this time, the plastic adhesive has a certain fluidity, which can better wet the surface of the battery cell 10 and fill the bonding gap. Under the pressure of the tooling, the softened bonding part 40 forms a good contact area with the battery cell 10, tightly bonding the overlapping parts of two adjacent battery cells 10 together. After cooling, it returns to the highly elastic state, and a firm bond is achieved by relying on the intermolecular forces.

[0029] In embodiments of the present invention, the adhesive portion 40 is cured before the electrical connection of two adjacent solar cells 10. The temperature at which the adhesive portion 40 transitions from a highly elastic state to a viscoelastic state is higher than the lamination temperature of the photovoltaic module and lower than the welding temperature for the electrical connection of the two adjacent solar cells 10. During the stringing process, the plastic adhesive transitions from a highly elastic state to a viscoelastic state, but during the lamination process, the plastic adhesive remains in a highly elastic state and does not transition to a viscoelastic state. Specifically, during the stringing process (the welding temperature is typically 200°C or higher), the adhesive portion 40, which has already been cured on the surface of the solar cell 10, transitions from a highly elastic state to a viscoelastic state. Simultaneously, under the pressure of the tooling, the softened adhesive portion 40 forms a good contact area with the solar cell 10, tightly bonding the overlapping area of ​​the two adjacent solar cells 10 together. After stringing, the viscoelastic bonding portion 40 transforms back into a highly elastic state, firmly bonding the overlapping areas of adjacent battery cells 10 together. Therefore, the bonding portion 40 prevents overall or partial displacement of battery cells during the stringing and lamination process. Understandably, during the lamination process (lamination temperature is typically 140-150℃), the bonding portion 40 remains in a highly elastic state and does not transform into a viscoelastic state. Therefore, both the bonding portion 40 and the support portion 30 can support adjacent battery cells 10, further preventing microcracks in the overlapping areas of the battery cells during lamination.

[0030] In embodiments of the present invention, the support portion 30 and the adhesive portion 40 can be arranged in any form at the overlapping area of ​​two adjacent battery cells 10, as long as the support portion 30 can support the two adjacent battery cells 10 and the adhesive portion 40 can bond the two adjacent battery cells 10.

[0031] In some embodiments of the present invention, such as Figure 4a , Figure 4b and Figure 4c As shown, the support portion 30 and the adhesive portion 40 are alternately arranged at the overlapping area of ​​two adjacent battery cells 10. This can prevent microcracks in the overlapping area of ​​the battery cells during the string bonding and lamination process, and also prevent overall or partial displacement of the battery cells during the string bonding and lamination process. For example, one support portion 30 and one adhesive portion 40 can be alternately arranged at the overlapping area of ​​two adjacent battery cells 10, or two support portions 30 and one adhesive portion 40 can be alternately arranged at the overlapping area of ​​two adjacent battery cells 10, or one support portion 30 and two adhesive portions 40 can be alternately arranged at the overlapping area of ​​two adjacent battery cells 10, or two support portions 30 and two adhesive portions 40 can be alternately arranged at the overlapping area of ​​two adjacent battery cells 10. This embodiment of the invention does not limit this, and all these arrangements can prevent microcracks in the overlapping area of ​​the battery cells during the string bonding and lamination process, and at the same time prevent overall or partial displacement of the battery cells during the string bonding and lamination process.

[0032] Since the support portion 30 and the adhesive portion 40 are alternately arranged at the overlap of two adjacent battery cells 10, the solder ribbon 20 can overlap with the adhesive portion 40, such as... Figure 4a As shown, it may also not overlap with the adhesive portion 40, such as Figure 4b and Figure 4c As shown. However, the placement of the solder strip 20 should preferably avoid the support portion 30 to prevent interference between the two during the cascading welding process. If the solder strip 20 does not overlap with the adhesive portion 40, a support portion 30 and an adhesive portion 40 can be provided between two adjacent solder strips 20, as shown. Figure 4c As shown, alternatively, only one support portion 30 or one adhesive portion 40 may be provided between two adjacent solder strips 20, such as... Figure 4b As shown, this embodiment of the invention does not impose limitations in this regard. If the solder strip 20 overlaps with the adhesive portion 40, a support portion 30 can be provided between two adjacent solder strips 20, such as... Figure 5a As shown, multiple support parts 30 can also be provided, such as Figure 5b As shown.

[0033] In some embodiments of the present invention, such as Figure 4aAs shown, the solder ribbon 20 passes through the adhesive portion 40 (i.e., the solder ribbon 20 overlaps with the adhesive portion 40), and the support portion 30 is located between two adjacent solder ribbons 20. The adhesive portion 40 not only prevents overall or partial displacement of the battery cells during the stringing and lamination process, but also prevents the solder ribbon 20 from shifting or detaching. Moreover, since the solder ribbon 20 passes through the adhesive portion 40, more space is provided for the support portion 30, which helps to improve the flexibility of the support portion 30 and allows for more support portions 30 and adhesive portions 40 to be provided at the edge of the battery cell 10.

[0034] In some embodiments of the present invention, the support portion 30 and the adhesive portion 40 may be overlapped at the overlap of two adjacent battery cells 10, such as... Figure 4d As shown, the support portion 30 and the adhesive portion 40 are overlapped, and at least a portion of the support portion 30 is embedded in the adhesive portion 40. This increases the contact area between them, thereby providing more resistance to prevent cell displacement during lamination. Therefore, the support portion 30 not only supports two adjacent cells 10 but also helps enhance the adhesion of the adhesive portion 40 to the two adjacent cells 10, further preventing overall or partial cell displacement during the stringing process from welding to lamination. Optionally, the support portion 30 is located between two adjacent solder strips 20, i.e., the adhesive portion 40 is also located between two adjacent solder strips 20, to avoid interference between the support portion 30 and the solder strips 20 during the stringing process.

[0035] The support portion 30 and the adhesive portion 40 are placed as close as possible to the edge of the solar cell 10 to avoid affecting the photoelectric conversion efficiency of the photovoltaic module. In some embodiments of the present invention, such as... Figure 5aAs shown, along the direction of the solder ribbon 20, the length (L1) of the support portion 30 from the edge of the solar cell 10 can be 0mm ≤ L1 ≤ 1.5mm. This allows the support portion 30 to support two adjacent solar cells 10 without reducing the photoelectric conversion efficiency of the photovoltaic module. Further, the length (L1) of the support portion 30 from the edge of the solar cell 10 is preferably 0.2mm ≤ L1 ≤ 0.8mm. For example, the length of the support portion 30 from the edge of the solar cell 10 can be 0.09mm, 0.22mm, 0.25mm, 0.28mm, 0.34mm, 0.4mm, 0.56mm, 0.75mm, or 0.1mm, and this embodiment of the invention does not impose any limitations on this. Similarly, along the direction of the solder ribbon 20, the length (L1) of the adhesive portion 40 from the edge of the solar cell 10 can be 0mm ≤ L1 ≤ 1.5mm. This allows the adhesive portion 40 to bond two adjacent solar cells 10 without reducing the photoelectric conversion efficiency of the photovoltaic module. Furthermore, the length (L1) of the adhesive portion 40 from the edge of the battery cell 10 is preferably 0.2mm ≤ L1 ≤ 0.8mm. For example, the length of the adhesive portion 40 from the edge of the battery cell 10 can be 0.09mm, 0.22mm, 0.25mm, 0.28mm, 0.34mm, 0.4mm, 0.56mm, 0.75mm, or 0.1mm, and this embodiment of the invention does not impose any limitations on this.

[0036] To further improve the encapsulation density of photovoltaic modules, in the embodiments of the present invention, the spacing (D1) between two adjacent cells 10 in the cell string can be -1.0mm ≤ D1 ≤ -0.2mm. It should be noted that if the overlap area between two adjacent cells is too large, it will result in an excessively large shading area of ​​the cells, causing unnecessary waste, and will also lead to greater stress at the solder joints in the overlap area, greatly increasing the risk of microcracks in the cells. Preferably, the spacing (D1) between two adjacent cells 10 is -0.6mm ≤ D1 ≤ -0.4mm. For example, the spacing between two adjacent cells 10 can be -0.52mm, -0.5mm, -0.48mm, -0.43mm, or -0.41mm; the embodiments of the present invention do not impose limitations on this.

[0037] This invention also provides a method for manufacturing a photovoltaic cell string, comprising: Step A: Apply solid adhesive and plastic adhesive along the edge of the overlapping area of ​​two adjacent battery cells 10 and cure them to form a support portion 30 and an adhesive portion 40 at the overlapping area of ​​the battery cells 10.

[0038] Step B involves connecting the edges of the two battery cells 10 in a shingled manner, such that the support portion 30 and the adhesive portion 40 are both located at the overlap of the two battery cells 10. The solder ribbon 20 is then soldered to the front main grid 105 of one battery cell 10 and the back main grid 106 of the other battery cell 10 to electrically connect the two adjacent battery cells 10.

[0039] In step A, the solid adhesive and the plastic adhesive can be applied along the same edge of the same battery cell 10 in two adjacent battery cells, or they can be applied along different edges of the same battery cell 10, or they can be applied along the edges of different battery cells 10. This embodiment of the invention does not limit the application of these methods. The solid adhesive can be selected from one or more of epoxy resin adhesives, phenolic resin adhesives, polyurethane adhesives, silicone adhesives, urea-formaldehyde resin adhesives, polyimide adhesives, and unsaturated polyester adhesives. The plastic adhesive can be selected from one or more of polyvinyl acetate adhesives, polyacrylate adhesives, EVA hot melt adhesives, polyamide adhesives, polyvinyl alcohol acetal adhesives, chlorinated polyvinyl resin adhesives, and polyurethane hot melt adhesives.

[0040] In an embodiment of the present invention, the temperature at which the adhesive portion 40 transitions from a highly elastic state to a viscoelastic state is higher than the lamination temperature of the photovoltaic module and lower than the welding temperature for electrically connecting two adjacent solar cells 10. Therefore, during the stringing process, the plastic adhesive transitions from a highly elastic state to a viscoelastic state, but during the lamination process, the plastic adhesive remains in a highly elastic state and does not transition from a highly elastic state to a viscoelastic state.

[0041] In some embodiments of the present invention, step A may include: applying a solid adhesive and a plastic adhesive along the same edge of the same battery cell 10, and then curing them to form a support portion 30 and an adhesive portion 40 at the edge of the battery cell 10, such as... Figure 6a , Figure 7a and Figure 8a As shown. It is understood that for two adjacent solar cells 10, only the same edge of one solar cell 10 needs to be applied with adhesive, and the other solar cell 10 does not need to be applied with adhesive. Moreover, the solid adhesive and the plastic adhesive can be applied alternately along the same edge of the same solar cell 10 so that the cured support part 30 and the adhesive part 40 do not overlap.

[0042] This invention does not limit the application location of the solid and plastic adhesives; the application location can be determined based on the positions of the support portion 30 and the bonding portion 40. Furthermore, this invention does not limit the amount of adhesive applied. Optionally, adhesive can be applied along a direction perpendicular to the main grid. Figure 6aand Figure 7a As shown, adhesive can be applied in the area between two adjacent main grids (e.g., front main grid 105), so that the support portion 30 and the adhesive portion 40 after curing are both located between the two adjacent main grids. For example, both solid adhesive and plastic adhesive can be applied in the area between every two adjacent main grids, so that the support portion 30 and the adhesive portion 40 are provided in the area between every two adjacent main grids. Alternatively, the application positions of the solid adhesive and the plastic adhesive can be located on opposite sides of the same main grid, so that only the support portion 30 or the adhesive portion 40 is provided in the area between every two adjacent main grids.

[0043] like Figure 8a As shown, the application position of the solid adhesive can be in the area between the two main grids (such as the front main grid 105), and the application position of the plastic adhesive can be at the main grid (such as the front main grid 105). Since the front main grid 105 of one of the two adjacent battery cells 10 is welded to the back main grid 106 of the other battery cell 10 by the solder ribbon 20, the solder ribbon 20 will be embedded in the bonding part 40 during the string welding process, which can prevent the solder ribbon 20 from shifting or desoldering.

[0044] In some embodiments of the present invention, step A may include: applying a solid adhesive along a first edge 101 on the front side of a battery cell 10 and curing it to form a support portion 30 at the edge of the battery cell 10, such as... Figure 9a and Figure 10a As shown; a plastic adhesive is applied along the second edge 104 of the back surface of another battery cell 10 and cured to form an adhesive portion 40 at the edge of the battery cell 10, as shown. Figure 9b and Figure 10b As shown. In some embodiments of the present invention, step A may include: applying a solid adhesive along the second edge 102 of the front side of a battery cell 10 and curing it to form a support portion 30 at the edge of the battery cell 10, such as... Figure 9a and Figure 10a As shown; a plastic adhesive is applied along the first edge 103 of the back surface of another battery cell 10 and cured to form an adhesive portion 40 at the edge of the battery cell 10, as shown. Figure 9b and Figure 10b As shown. It can be understood that for two adjacent solar cells 10, solid adhesive and plastic adhesive are applied along the edges of different solar cells 10, so that the cured support part 30 and adhesive part 40 are located at the edges of different solar cells 10.

[0045] It should be noted that if the solid adhesive and the plastic adhesive are applied separately to the edges of different battery cells 10, the application positions of the solid adhesive and the plastic adhesive may or may not overlap. For example... Figure 9a and Figure 9b As shown, the application location of the solid adhesive is within the area between two adjacent main grids (e.g., the back main grid 106), while the application location of the plastic adhesive is at the position of the main grid (e.g., the front main grid 105). The application locations of the two do not overlap. Figure 10a and Figure 10b As shown, the application position of the solid adhesive is in the area between two adjacent main grids (such as the back main grid 106), and the application position of the plastic adhesive is also in the area between two adjacent main grids (such as the front main grid 105), and the application positions of the two overlap.

[0046] Optionally, the application method of the solid adhesive can be one or a combination of printing, dispensing, or spraying, and the application method of the plastic adhesive can be one or a combination of printing, dispensing, or spraying. Optionally, the curing method of the solid adhesive can be one or a combination of photocuring and thermocuring, and the curing method of the plastic adhesive can also be one or a combination of photocuring and thermocuring.

[0047] The cured support portion 30 and adhesive portion 40 are placed as close as possible to the edge of the solar cell 10 to avoid affecting the photoelectric conversion efficiency of the photovoltaic module. In some embodiments of the present invention, such as... Figure 5a As shown, along the direction of the main grid, the length (L1) of the support portion 30 from the edge of the solar cell 10 can be 0mm ≤ L1 ≤ 1.5mm. This allows the support portion 30 to support two adjacent solar cells 10 without reducing the photoelectric conversion efficiency of the photovoltaic module. Further, the length (L1) of the support portion 30 from the edge of the solar cell 10 is preferably 0.2mm ≤ L1 ≤ 0.8mm. Similarly, along the direction of the main grid, the length (L1) of the adhesive portion 40 from the edge of the solar cell 10 can be 0mm ≤ L1 ≤ 1.5mm. This allows the adhesive portion 40 to bond two adjacent solar cells 10 without reducing the photoelectric conversion efficiency of the photovoltaic module. Further, the length (L1) of the adhesive portion 40 from the edge of the solar cell 10 is preferably 0.2mm ≤ L1 ≤ 0.8mm.

[0048] In step A, as Figure 11As shown, along the thickness direction of the solar cell 10, the height (H2) of the cured adhesive portion 40 is greater than the height (H1) of the cured support portion 30. The support portion 30 provides self-support, while the adhesive portion 40 relies on the high temperature and tooling pressure during the string welding process to bond adjacent solar cells 10 together. It should be noted that the heights of the support portion 30 and the adhesive portion 40 also depend on the height of the solder ribbon 20 at the overlap of adjacent solar cells 10. The height of the support portion 30 should be greater than or equal to the height of the solder ribbon 20 at the overlap of solar cells 10, so that the support portion 30 can support the two adjacent solar cells 10 and prevent the solder ribbon 20 from making hard contact with the solar cell 10.

[0049] Optionally, in step A, the height (H1) of the cured support portion 30 can be 100μm ≤ H1 ≤ 300μm. If the height of the support portion 30 is too high, the solar cell will deform significantly at the edges, leading to cell cracking during lamination. If the height of the support portion 30 is too low, stress will remain concentrated at the location of the solder ribbon, also easily causing cell cracking during lamination. Further, the height (H2) of the cured adhesive portion 40 can be 100μm ≤ H2 ≤ 350μm, and H2 > H1. It is understood that the height of the support portion 30 should be greater than or equal to the height of the solder ribbon 20 at the overlapping point of the solar cells 10. Under welding temperature and tooling pressure, the support portion 30 serves to support the two adjacent solar cells 10, preventing hard contact between the solder ribbon 20 and the solar cells 10.

[0050] Optionally, in step A, the cured support portion 30 can be a combination of one or more of the following: a strip shape, a dot shape, and the cured adhesive portion 40 can be a combination of one or more of the following: a strip shape, a dot shape. If the support portion 30 is a strip shape, then along the direction perpendicular to the main grid, the length (L2) of the support portion 30 can be 1mm ≤ L2 ≤ 5mm, and along the direction of the main grid, the width (W1) of the support portion 30 can be 0.2mm ≤ W1 ≤ 2mm; if the support portion 30 is a dot shape, then the diameter ( Φ 1) Can be 0.2mm≤ Φ 1≤2mm. Similarly, if the adhesive part 40 is elongated, then along the direction perpendicular to the main grid, the length (L2) of the adhesive part 40 can be 1mm≤L2≤5mm, and along the direction of the main grid, the width (W1) of the adhesive part 40 can be 0.2mm≤W1≤2mm; if the adhesive part 40 is dot-shaped, then the diameter of the adhesive part 40 ( Φ 1) Can be 0.2mm≤ Φ 1≤2mm.

[0051] In step B, one or more of infrared welding, laser welding, and ultrasonic welding can be used to weld the welding strip 20 to the front main grid 105 of one battery cell 10 and the back main grid 106 of another battery cell 10, so that the front main grid 105 of one battery cell 10 and the back main grid 106 of another battery cell 10 are electrically connected through the welding strip 20.

[0052] Because the support portion 30 uses a solid adhesive, it remains cured during the stringing process (welding temperature is typically 200°C or higher) to provide self-support and prevent hard contact between the solder ribbon 20 and the battery cell 10. Because the adhesive portion 40 is made of a plastic adhesive, it softens and deforms (transforming from a highly elastic state to a viscoelastic state) on the surface of the battery cell 10 during the stringing process (welding temperature is typically 200°C or higher). Under tooling pressure, the softened adhesive portion 40 forms a good contact area with the battery cell 10, tightly bonding the overlapping areas of adjacent battery cells 10 together. Figure 6b , Figure 7b , Figure 8b , Figure 9c and Figure 10c As shown. After stringing, the viscoelastic bonding portion 40 transforms back into a highly elastic state, firmly bonding the overlapping areas of adjacent solar cells 10 together, resulting in good adhesion. The support portion 30 ensures a certain height difference in the overlapping areas of adjacent solar cells 10, so that stress is evenly distributed on the support portion 30 and the bonding portion 40, and does not concentrate at the location of the solder strip 20, thereby preventing microcracks in the overlapping areas of the solar cells during the stringing and lamination process. The bonding portion 40 ensures that the welded photovoltaic cell strings maintain adhesion between cells during transport, arrangement, and lamination, preventing displacement.

[0053] In an embodiment of the present invention, the height (H2) of the adhesive portion 40 after initial curing is greater than the height (H1) of the support portion 30 after curing. Therefore, in the stringing process, the support portion 30 serves to support two adjacent battery cells 10. The support portion 30 ensures that, under the pressure of the tooling, the height of the adhesive portion 40 after re-curing is greater than or equal to the height of the solder ribbon 20 at the overlap of the battery cells 10, thereby preventing the solder ribbon 20 from making hard contact with the battery cells 10. It should be noted that if the support portion 30 is not provided at the edge of the battery cells 10, and the adhesive portion 40 alone achieves both the supporting and adhesive functions, then, due to the combined effects of welding temperature and tooling pressure during the stringing process, the thickness of the adhesive portion 40 after stringing is much lower than the thickness of the solder ribbon 20 at the overlap of the two adjacent battery cells 10, resulting in hard contact between the solder ribbon 20 and the battery cells 10. This can easily lead to microcracks or cracks in the battery cells during subsequent lamination.

[0054] like Figure 8b and Figure 9c As shown, since the application position of the solid adhesive is in the area between the two main grids (such as the front main grid 105), and the application position of the plastic adhesive is at the position of the main grid, in the stringing process, the solder ribbon 20 connecting the front main grid 105 of one battery cell 10 and the back main grid 106 of another battery cell 10 will be embedded in the softened adhesive portion 40. After the stringing is completed, the solder ribbon 20 is fixed in the adhesive portion 40 to prevent the solder ribbon 20 from shifting or detaching.

[0055] like Figure 10c As shown, the application positions of the solid adhesive and the plastic adhesive overlap. Therefore, during the stringing process, the support portion 30 is embedded in the softened adhesive portion 40. After the stringing is completed, the support portion 30 and the adhesive portion 40 are overlapped and at least a portion of the support portion 30 is embedded and fixed in the adhesive portion 40. The contact area between the two increases, thus providing more resistance to prevent cell displacement during lamination. Therefore, the support portion 30 not only supports two adjacent cells 10, but also helps to enhance the adhesion of the adhesive portion 40 to the two adjacent cells 10, further preventing overall or partial cell displacement during the stringing and lamination process.

[0056] It should be noted that the stress at the location of the solder strip 20 where two adjacent battery cells 10 overlap is related to the height of the solder strip 20 at that location. In the embodiment of the present invention, in step B, the solder strip 20 at the overlap of two adjacent battery cells 10 can be either flat or circular, preferably flat. The purpose is to reduce the stress of the solder strip 20 at the overlap and prevent excessive stress from causing microcracks or cracks in the battery cells. In addition, it can also reduce the amount of adhesive (solid adhesive and plastic adhesive) applied, thereby reducing the manufacturing cost.

[0057] In step B, the spacing (D1) between two adjacent cells 10 in the battery string can be -1.0mm ≤ D1 ≤ -0.2mm. It should be noted that if the overlap area between two adjacent cells is too large, it will result in an excessively large shading area, causing unnecessary waste, and will also lead to greater stress at the solder joints in the overlap area, greatly increasing the risk of microcracks in the cells. Preferably, the spacing (D1) between two adjacent cells 10 is -0.6mm ≤ D1 ≤ -0.4mm.

[0058] After obtaining the photovoltaic cell string using the above method, it is further arranged, and then the cover plate, front encapsulant film, photovoltaic cell string, back encapsulant film and back sheet are sequentially stacked, and then laminated to obtain the photovoltaic module.

[0059] During the lamination process (lamination temperature is typically 140-150℃), the adhesive portion 40 remains in a highly elastic state and does not transition to a viscoelastic state. The adhesive portion 40 serves to bond adjacent battery cells 10, preventing overall or partial displacement of the battery cells during the string bonding and lamination process. Furthermore, both the adhesive portion 40 and the support portion 30 can support adjacent battery cells 10, further preventing microcracks in the overlapping areas of the battery string during lamination. Moreover, during the lamination process, the high-temperature molten adhesive film can flow into and fill the overlapping areas of adjacent battery cells 10.

[0060] To further improve the encapsulation density of photovoltaic modules, in embodiments of the present invention, the string spacing (D2) between two adjacent photovoltaic cell strings in the photovoltaic module can be 0.2mm ≤ D2 ≤ 1.0mm. Preferably, the string spacing can be 0.3mm ≤ D2 ≤ 0.5mm.

[0061] This invention provides a support portion 30 and an adhesive portion 40 at the overlapping area of ​​two adjacent solar cells 10. The support portion 30 is cured before welding and lamination and remains unchanged during welding and lamination to support the two adjacent solar cells 10. The adhesive portion 40 is cured before welding and changes from a highly elastic state to a viscoelastic state during welding to bond the two adjacent solar cells 10. It remains unchanged during lamination to prevent the solar cells 10 from shifting. Therefore, the solar cell string manufacturing method provided by this invention can prevent microcracks in the overlapping area of ​​the solar cells during the string welding and lamination process, and can also prevent overall or partial shifting of the solar cells during the string welding and lamination process. This results in increased photovoltaic module packaging density and increased power generation per unit area. Moreover, the process steps are simple, and the compatibility and automation levels are high.

[0062] During lamination, variations in internal height or thickness can cause areas with higher height or greater thickness to experience greater stress, leading to excessive film flow in those areas and causing cell displacement. Furthermore, with the increasing integration of modules, string spacing has gradually moved from the industry-standard 1.5-2mm to the leading-edge 0.2-0.5mm. Even slight cell displacement at this 0.2-0.5mm level can cause appearance abnormalities or even serious problems such as internal short circuits. This invention proposes providing a support portion 30 and an adhesive portion 40 at the overlap of two adjacent cells 10. During lamination, the adhesive portion 40 not only provides joint support for the two adjacent cells 10, further dispersing stress and preventing microcracks or breakage during lamination, but also bonds the two adjacent cells 10 together, preventing cell displacement.

[0063] Example 1

[0064] S1: A solid adhesive is printed on the first edge 101 on the front side of the battery cell 10, 0.2 mm away from the edge and at the center of the two adjacent front main grids 105, and then cured by a UV lamp. The cured support part 30 has a width of 1 mm, a length of 2 mm, and a height of 200 μm. S2: A plastic adhesive is printed at the first edge 101 on the front side of the battery cell 10, 0.2 mm away from the edge and at the position of the main grid 105 on the front side, and then cured by a UV lamp. The cured adhesive part 40 has a width of 1.5 mm, a length of 4 mm, and a height of 300 μm. By performing the above steps, multiple photovoltaic cells are obtained; S3: Connect multiple photovoltaic cells in series via solder ribbon 20 to form a photovoltaic cell string; wherein, the height of the solder ribbon after being flattened is 150μm.

[0065] Example 2

[0066] S1: A solid adhesive is printed at the first edge 101 on the front side of a battery cell 10, 0.2 mm from the edge and at the center of two adjacent front main grids 105, and then cured by a UV lamp. The cured support part 30 has a width of 1 mm, a length of 2 mm, and a height of 200 μm. S2: A plastic adhesive is printed on the second edge 104 on the back of another cell 10, 0.2 mm from the edge and at the position of the back main grid 106, and then cured by a UV lamp. The cured adhesive part 40 has a width of 1.5 mm, a length of 4 mm, and a height of 300 μm. By performing the above steps, multiple photovoltaic cells are obtained; S3: Connect multiple photovoltaic cells in series using solder ribbons to form a photovoltaic cell string; wherein, the height of the solder ribbon after being flattened is 150μm.

[0067] Example 3

[0068] S1: A solid adhesive is printed at the second edge 104 on the back of a battery cell 10, 0.2 mm from the edge and at the center of two adjacent back main grids 106, and then cured by a UV lamp. The cured support part 30 has a width of 1 mm, a length of 2 mm, and a height of 200 μm. S2: Plastic adhesive is printed at the first edge 101 on the front side of another battery cell 10, 0.2 mm from the edge and at the center of the two adjacent front main grids 105, and then cured by UV lamp. The cured adhesive part 40 has a width of 1.5 mm, a length of 4 mm, and a height of 300 μm. By performing the above steps, multiple photovoltaic cells are obtained; S3: Connect multiple photovoltaic cells in series using solder ribbons to form a photovoltaic cell string; wherein the thickness of the solder ribbon after flattening is 150μm.

[0069] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can occur depending on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A photovoltaic cell string, characterized in that, It includes multiple battery cells (10) and multiple solder strips (20), and the front main grid of one of two adjacent battery cells (10) is electrically connected to the back main grid of the other battery cell (10) through the solder strips (20); The edges of two adjacent battery cells (10) are connected in a shingled manner, and a support portion (30) and an adhesive portion (40) are provided at the overlapping part of two adjacent battery cells (10). The support portion (30) is made of a solid adhesive, and the bonding portion (40) is made of a plastic adhesive. The support portion (30) is cured before the two adjacent battery cells (10) are electrically connected; The adhesive portion (40) is cured before the two adjacent cells (10) are electrically connected, and the temperature at which it changes from a high-elastic state to a viscoelastic state is higher than the lamination temperature of the photovoltaic module and lower than the welding temperature of the two adjacent cells (10) being electrically connected.

2. The photovoltaic cell string according to claim 1, characterized in that, The support portion (30) and the adhesive portion (40) are alternately arranged.

3. The photovoltaic cell string according to claim 2, characterized in that, The welding strip (20) passes through the adhesive portion (40), and the support portion (30) is located between two adjacent welding strips (20).

4. The photovoltaic cell string according to claim 1, characterized in that, The support portion (30) overlaps with the adhesive portion (40) and at least a portion of the support portion (30) is embedded in the adhesive portion (40).

5. The photovoltaic cell string according to claim 4, characterized in that, The support portion (30) and the adhesive portion (40) are located between two adjacent welding strips (20).

6. A method for manufacturing a photovoltaic cell string, characterized in that, include: Step A: Apply solid adhesive and plastic adhesive along the edge of the overlapping area of ​​two adjacent battery cells (10) and cure them to form a support part (30) and an adhesive part (40) at the overlapping area of ​​two adjacent battery cells (10). Step B: The edges of the two battery cells (10) are connected in a shingled manner, so that the support part (30) and the adhesive part (40) are both located at the overlap of the two battery cells (10). The solder strip (20) is soldered to the front main grid of one of the two battery cells (10) and the back main grid of the other battery cell (10) to electrically connect the two adjacent battery cells (10). The temperature at which the adhesive portion (40) transitions from a high-elastic state to a viscoelastic state is higher than the lamination temperature of the photovoltaic module and lower than the welding temperature at which the two adjacent cells (10) are electrically connected.

7. The method for manufacturing a photovoltaic cell string according to claim 6, characterized in that, In step A, along the direction of the thickness of the battery cell (10), the height of the cured adhesive portion (40) is greater than the height of the cured support portion (30).

8. The method for manufacturing a photovoltaic cell string according to claim 6, characterized in that, Step A includes: The solid adhesive and the plastic adhesive are applied along the same edge of the same battery cell (10) in two adjacent battery cells (10) and cured to form a support portion (30) and an adhesive portion (40) at the edge of the battery cell (10). or, A solid adhesive is applied along the first edge (101) of the front side of one battery cell (10) and cured to form a support portion (30) at the edge of the battery cell (10); a plastic adhesive is applied along the second edge (104) of the back side of another battery cell (10) and cured to form an adhesive portion (40) at the edge of the battery cell (10). or, A solid adhesive is applied along the second edge (102) of the front side of one battery cell (10) and cured to form a support portion (30) at the edge of the battery cell (10); a plastic adhesive is applied along the first edge (103) of the back side of another battery cell (10) and cured to form an adhesive portion (40) at the edge of the battery cell (10).

9. The method for manufacturing a photovoltaic cell string according to claim 6, characterized in that, The support portion (30) and the adhesive portion (40) are alternately arranged. And / or, The welding strip (20) passes through the adhesive portion (40), and the support portion (30) is located between two adjacent welding strips (20).

10. The method for manufacturing a photovoltaic cell string according to claim 6, characterized in that, The support portion (30) overlaps with the adhesive portion (40), and at least a portion of the support portion (30) is embedded within the adhesive portion (40). And / or, The support portion (30) and the adhesive portion (40) are located between two adjacent welding strips (20).

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