Photovoltaic cell string and photovoltaic module

Abstract

The utility model discloses a photovoltaic cell string and a photovoltaic assembly, and relates to the technical field of photovoltaic power generation. According to one specific embodiment, the photovoltaic cell string comprises a cell piece, a welding strip and a first insulating strip, the battery pieces are connected in series through the welding strip to form a battery string; the first insulating strip is adhered to the back surface of the first end of the battery string; and the front welding strip of the first end of the battery string extends out of the edge of the first end of the battery string, is folded to the back surface of the first end of the battery string and is adhered to the first insulating strip. According to the embodiment, the assembly short-circuit risk can be reduced, and the assembly yield is improved.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic power generation technology, and in particular to a photovoltaic cell string and a photovoltaic module. Background Technology

[0002] Photovoltaic modules convert light energy into electrical energy through the photovoltaic effect of solar cells, and then export the collected electrical energy. Currently, in order to increase the light-receiving area of ​​the module and improve its efficiency, the busbars used to connect the cell strings can be hidden on the back of the module.

[0003] In existing technologies, using positioning tape to fix the insulating strip is not very effective. The insulating strip is prone to movement when the front solder strip is folded, leading to a higher risk of short circuits in the module. After the front solder strip is folded, the solder strip portion at the edge of the cell string is thicker. During the subsequent lamination process, the amount of adhesive film filling between the busbar and the cell, as well as between the front solder strip and the front glass of the module, will be too small, increasing the risk of cell breakage and glass fracture, and affecting the module yield. Utility Model Content

[0004] In view of this, the present invention provides a photovoltaic cell string and a photovoltaic module, which can reduce the risk of module short circuit and improve module yield.

[0005] To achieve the above objectives, in one aspect, the present invention provides the following technical solution:

[0006] This utility model provides a photovoltaic cell string, including cell panels, solder strips, and a first insulating strip; the cell panels are connected in series to form a cell string via the solder strips; the first insulating strip is adhered to the back side of the first end of the cell string; the front solder strip of the first end of the cell string extends beyond the edge of the first end of the cell string, and is folded to the back side of the first end of the cell string and adhered to the first insulating strip.

[0007] To achieve the above objectives, in another aspect, this utility model provides the following technical solution:

[0008] This utility model provides a photovoltaic module, including a photovoltaic cell string and a first busbar; multiple cell strings are arranged to form a cell array, and the first busbar is welded to the front solder strip of the back side of the first end of multiple cell strings in the same column or row of the cell array after being folded.

[0009] The technical solution of this utility model embodiment has the following advantages or beneficial effects:

[0010] This embodiment of the invention places an insulating strip on the surface of the battery string and then fixes it using methods such as adhesive bonding, thereby avoiding the risk of short circuits in the module caused by the movement of the insulating strip. This embodiment of the invention also reduces the thickness of the solder strip in the edge area of ​​the battery string by means of staggered folding, staggered bending, and removal of the back solder strip at the ends of the battery string, increasing the amount of adhesive film filling between the busbar and the battery cell, and between the front solder strip and the front glass of the module, reducing the risk of battery breakage and glass cracking, and improving the module yield.

[0011] The further effects of the aforementioned unconventional alternative methods will be explained below in conjunction with specific implementation methods. Attached Figure Description

[0012] The accompanying drawings are provided to better understand this utility model and do not constitute an undue limitation thereof. Wherein:

[0013] Figure 1 This is a top view of the back of the battery string according to an embodiment of the present invention;

[0014] Figure 2 This is a schematic diagram of the external shape of the insulating strip and the pad strip according to an embodiment of the present utility model;

[0015] Figure 3 This is a schematic diagram of the removal of the back solder strip in an embodiment of this utility model;

[0016] Figure 4 This is a schematic diagram of the extended back solder strip in an embodiment of this utility model;

[0017] Figure 5 This is a schematic diagram of the welding of the back solder strip and the busbar according to an embodiment of the present invention;

[0018] Figure 6 These are schematic diagrams of the front and back sides of the battery cell according to an embodiment of this utility model;

[0019] Figure 7 This is a schematic diagram of the busbar according to an embodiment of the present utility model;

[0020] Figure 8 This is a schematic diagram of the shape of the pressure-sensitive adhesive film before pressure is applied, according to an embodiment of this utility model.

[0021] Explanation of reference numerals in the attached figures:

[0022] 1-Battery cell, 11-Battery string, 21-Front solder strip, 22-Back solder strip, 31-First insulating strip, 32-First pad, 33-First transparent pad, 34-Middle pad, 41-First busbar, 42-Second busbar, 43-Middle busbar, 5-Pressure-sensitive adhesive film, 51-Through hole, A-First end, B-Second end. Detailed Implementation

[0023] The following description, in conjunction with the accompanying drawings, illustrates exemplary embodiments of the present invention, including various details to aid understanding. These embodiments should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0024] First, the technical concept of this utility model embodiment will be explained. The current photovoltaic module manufacturing process can be divided into the following steps: dicing, stringing, layout, stacking, lamination, framing, curing, and cleaning. Specifically, the dicing step is used to form solar cells; the stringing step is used to connect solar cells in series to form solar strings using methods such as infrared stringing; the layout step is used to arrange and lay out multiple solar strings in an orderly manner according to the layout design; the stacking step is used to orderly stack the front glass, solar strings, encapsulant film, backsheet, etc., and to weld the busbars to multiple solar strings; the lamination step is used to tightly press the stacked materials together; the framing step is used to place the pressed material into a frame and seal it; the curing step is used to cure materials such as silicone; and the cleaning step is used to clean surface impurities.

[0025] To increase the light-receiving area of ​​the module by hiding the busbar behind the battery string, the front solder strip at one end of the battery string can be folded to the back. The solder strip and busbar are then welded to the back, and an insulating strip is used to electrically isolate the folded front solder strip from the back of the battery string. In existing technology, positioning tape is used to fix the insulating strip, but the fixing effect is poor. The insulating strip is prone to movement when the front solder strip is folded, leading to a high risk of short circuit in the module. To address this problem, this embodiment of the invention pre-fixes and bonds insulating strips or other materials to the surface of the battery string. After the solder strip is folded, the insulating strip is bonded to both the surface of the battery string and the folded solder strip. This avoids the risk of short circuit in the module caused by the movement of the insulating strip. Furthermore, the insulating strips or other materials fixed to the surface of the battery string also prevent the solder strip from contacting or pressing on the battery cells during folding, thus preventing cell cracking. Optionally, in this embodiment of the invention, the outer edge of the insulating strip can be set as a serrated or similar shape, with the serrated opening extending beyond the edge of the battery string. Each solder strip is folded at the corresponding serrated opening, thereby preventing cracking caused by the folding of the solder strip through the serrated opening. The serrated opening of the insulating strip can also fix the solder strip and prevent it from shifting when folded.

[0026] Furthermore, the inventors of this invention have discovered that in the prior art, after the front solder strip is folded, the area containing the solder strip, insulating strip, and busbar has a significantly increased thickness compared to other areas. This area experiences greater pressure during lamination, which can lead to insufficient adhesive film filling between the busbar and the cell, and between the front solder strip and the front glass of the module, increasing the risk of cell breakage and glass fracture, thus affecting module yield. To address this issue, embodiments of this invention reduce the solder strip thickness at the edge of the cell string by using methods such as staggered folding, staggered bending, and removal of the back solder strip at the end of the cell string. This reduces the pressure and increases the adhesive film filling between the busbar and the cell, and between the front solder strip and the front glass of the module, further reducing the risk of cell breakage and glass fracture and improving module yield. In addition, in one embodiment, to further reduce the pressure in this area, an EPE adhesive film can be added to the short side of the module, from the cell edge to the glass edge, increasing the thickness of this area and thus reducing the pressure on the folded area.

[0027] It is worth noting that the terms "first," "second," etc., included in the terminology of this utility model embodiment are used to distinguish similar objects, and are not necessarily used to describe a specific number or order. It should be understood that such terms can be used interchangeably where appropriate; this is merely a distinguishing method adopted in the description of objects with the same attributes in the embodiments of this utility model. Where there is no conflict, the embodiments of this utility model and the technical features within them can be combined with each other.

[0028] This utility model provides a photovoltaic cell string, see [link]. Figure 1 , Figure 2 The battery string of this embodiment includes battery cells 1, solder ribbons, and a first insulating strip 31. The solder ribbons include a front solder ribbon 21 and a back solder ribbon 22. The battery cells 1 are connected in series by the solder ribbons to form a battery string 11; the first insulating strip 31 is bonded to the back of the first end A of the battery string 11; the front solder ribbon 21 of the first end A of the battery string 11 extends out of the edge of the first end A of the battery string 11, and is folded to the back of the first end A of the battery string 11 and bonded to the first insulating strip 31. Exemplarily, the method of connecting the battery cells 1 in series to form a battery string 11 using solder ribbons can be infrared welding, soldering adhesive, coating, etc.

[0029] The first end A refers to the end of the battery string 11 where the front solder strip 21 needs to be welded to the busbar. Correspondingly, the second end B refers to the end of the battery string 11 where the back solder strip 22 needs to be welded to the busbar. Preferably, the solder strips (including the front solder strip 21 and the back solder strip 22) in this embodiment can be conventional solder strips with a melting range of 185-190℃, or they can be low-temperature solder strips with a melting range of 124℃-151℃. The solder strip diameter is 0.15mm-0.22mm; in some embodiments, the solder strip diameter can be 0.15mm, 0.18mm, 0.2mm, or 0.22mm.

[0030] A first insulating strip 31 is disposed on the back side of the first end A of the battery string 11, and is bonded to both the folded front solder strip 21 and the back side of the first end A of the battery string 11. The first insulating strip 31 electrically isolates the folded front solder strip 21 from the back side of the first end A of the battery string 11. Exemplarily, the width of the first insulating strip 31 can be 10mm-15mm; in some embodiments, the width of the first insulating strip 31 can be 10mm, 12mm, or 15mm. The length of the first insulating strip 31 is consistent with the dimensions of the battery cell 1, and the thickness is 0.2mm-0.28mm; in some embodiments, the thickness of the first insulating strip 31 can be 0.2mm, 0.22mm, 0.24mm, 0.26mm, or 0.28mm.

[0031] For example, the first insulating strip 31 can be a double-layer or triple-layer structure. In a double-layer structure, the outer layer is EVA (Ethylene Vinyl Acetate Copolymer), and the inner layer is insulating materials such as PET (Polyethylene terephthalate) or PVDF (Polyvinylidene fluoride). In a triple-layer structure, the upper and lower outer layers are EVA, and the middle layer is insulating materials such as PET or PVDF. In practical applications, the first insulating strip 31 can be heated by a heating device, and bonding can be achieved through the properties of EVA. The above structural design of the first insulating strip 31 facilitates the bonding of materials to the battery string 11 and the solder strip, and also acts as a buffer, improving the process yield. The first insulating strip 31 contains an EVA layer, and after lamination, the corresponding area is free of voids and less prone to air bubbles, thereby improving the reliability of the component. A heat insulation layer can be added inside the first insulating strip 31, so that the solder strip below the insulating strip will not be affected when welding the busbar.

[0032] In this way, by bonding the first insulating strip 31 to the surface of the battery string 11 and the folded solder strip respectively, the risk of short circuit of the component caused by the movement of the insulating strip can be avoided. The first insulating strip 31 fixed to the surface of the battery string 11 can also keep the folding point away from the edge of the battery cell, avoiding the risk of the battery cell 1 breaking when the solder strip is folded.

[0033] As a preferred embodiment, the front solder strip 21 includes an original segment located on the front side of the first end A of the battery string 11 before folding and a folded segment located on the back side of the first end A of the battery string 11 after folding, with the original segment and the folded segment being staggered. This design ensures that the front solder strip 21 does not overlap in the thickness direction before and after folding, reducing the solder strip thickness at the edge of the battery string 11, thereby increasing the amount of encapsulant filling between the busbar and the battery cell 1, as well as between the front solder strip 21 and the front glass of the module, reducing the risk of battery breakage and glass cracking.

[0034] In one embodiment, the first insulating strip 31 is perpendicular to the extending direction of the battery string 11. For example... Figure 2 As shown, the first insulating strip 31 has evenly spaced serrations on the side near the first end A of the battery string 11, with the openings facing the first end A of the battery string 11. Each serration opening corresponds one-to-one with the front solder strip 21, and the front solder strip 21 is folded at the bottom of the corresponding serration opening. Preferably, the bottom of the serration opening can be set to extend beyond the edge of the battery string 11. This design facilitates control of the folding point position when the solder strip is folded, keeping the bending point away from the edge of the battery cell, reducing the risk of microcracks in the battery cell during the manufacturing process, and improving yield. The serration openings of the first insulating strip 31 can also fix the solder strip, preventing it from shifting during folding and affecting the appearance. Optionally, the first insulating strip 31 can also be other shapes with similar functions. Exemplarily, the serration opening width is 1mm-2mm; in some embodiments, the serration opening width can be 1mm, 1.5mm, or 2mm. The serration opening depth is 1mm-2mm; in some embodiments, the serration opening depth can be 1mm, 1.5mm, or 2mm. The bottom of the serrated opening extends 1mm-2mm beyond the edge of the battery string 11. In some embodiments, the bottom of the serrated opening extends 1mm, 1.5mm or 2mm beyond the edge of the battery string 11.

[0035] See Figure 3 , Figure 3The upper surface of the solar cell 1 is the back side. In one embodiment, the module reliability can be improved by further reducing the solder strip thickness at the edge of the cell string 11 through the following design. Specifically, when the grid distribution is changed, the first region on the back side of the first end A of the cell string 11 is not provided with a back solder strip 22; the first region is a region less than a preset first distance from the edge of the cell string 11, and the first distance is greater than the length of the front solder strip 21 after folding; the first insulating strip 31 is directly bonded to the back side of the first end A of the cell string 11. Since the first region on the back side of the first end A of the cell string 11 originally did not have a back solder strip 22 or the back solder strip 22 was removed in advance, the edge of the cell string 11 has a smaller solder strip thickness after the front solder strip 21 is folded, thereby further reducing the risk of cell breakage and glass breakage and improving the module yield. The above first distance can be set as needed to an applicable distance greater than the length of the front solder strip 21 after folding.

[0036] For the second terminal B of the battery string 11, existing technology generally involves directly welding the busbar to the back solder strip. This welding method suffers from problems such as weak welding, damage to the solder joint, and cracking during welding. To address this issue, this utility model provides two solutions, in which the battery string 11 includes a first spacer strip 32. The first spacer strip 32 is as follows... Figure 2 As shown, the first spacer strip 32 can be made of transparent or opaque materials, and can be made of insulating or non-insulating materials. It can have a certain degree of pre-crosslinking (e.g., 8%-10%) to provide cushioning and protection. More preferably, the first spacer strip 32 is made of an optically transparent material, so as not to affect the light reception on the back of the battery string 11. Exemplarily, the material of the first spacer strip 32 can be EVA, EPE (Ethylene-Propylene Elastomer, a multilayer structural material), or other adhesive film materials. In practical applications, the first spacer strip 32 can be heated by a heating device to achieve bonding. Optionally, a heat insulation layer can be added inside the first spacer strip 32 so as not to affect the solder strip below the first spacer strip 32 when welding the busbar. Exemplarily, the length of the first spacer strip 32 can be consistent with the dimensions of the battery cell 1, and the width can be 10mm-25mm, for example, 10mm, 15mm, 20mm, or 25mm.

[0037] For the first method, please refer to [link / reference]. Figure 5The back solder strip 22 of the second end B of the battery string 11 is located inside the second end B of the battery string 11 or flush with the edge of the second end B of the battery string 11. The first pad 32 is bonded to the back of the second end B of the battery string 11. In this manner, the first pad 32 provides cushioning when the back solder strip 22 is welded to the busbar, thereby improving welding reliability and avoiding damage to the solder joint or cracking during welding. In one embodiment, when the back solder strip 22 of the second end B of the battery string 11 is located inside the second end B of the battery string 11 or flush with the edge of the second end B of the battery string 11, the first pad 32 is perpendicular to the extension direction of the battery string 11. The first pad 32 is provided with connection holes corresponding one-to-one with the back solder strip 22, and the busbar is welded to the back solder strip 22 through these connection holes. This invention does not limit the size or shape of the connection holes; the shape can be rectangular, and holes can be opened on one side of the first pad 32. The connection holes are used for contact between the back solder strip 22 and the second busbar 42, facilitating subsequent welding steps.

[0038] In another embodiment, the first pad 32 is perpendicular to the extension direction of the battery string 11. The outer side of the first pad 32 is provided with equally spaced serrations with openings facing the outside of the battery string 11. The openings of the serrations correspond one-to-one with the back solder strips 22. The busbar is welded to the back solder strips 22 exposed at the openings of the serrations of the first pad 32.

[0039] For the second method, please refer to [link / reference]. Figure 1 The portion of the back solder strip 22 extending beyond the edge of the second end B of the battery string 11 is bent on the back side of the second end B of the battery string 11. One surface of the first spacer strip 32 is bonded to the back of the second end B of the battery string 11, and the other surface of the first spacer strip 32 is bonded to the bent back solder strip 22. This design improves the welding reliability between the busbar and the back solder strip 22 by utilizing the buffering effect of the first spacer strip 32, preventing damage to the solder joint and cracking during welding. When the back solder strip 22 is bent, the first spacer strip 32 also restricts the solder strip and fixes the bending point, thereby improving process yield.

[0040] Preferably, in the second embodiment, when the portion of the back solder strip 22 extending beyond the edge of the second end B of the battery string 11 is bent on the back side of the second end B of the battery string 11, the back solder strip 22 includes an original segment before bending and a folded segment after bending, with the original segment and the folded segment offset from each other. This design ensures that the back solder strip 22 does not overlap in the thickness direction before and after bending, reducing the thickness of the back solder strip 22 at the edge of the battery string 11, thereby increasing the amount of adhesive film filling in subsequent processes and reducing the risk of battery breakage and glass breakage.

[0041] In one embodiment of the second method, the length of the bent back solder strip 22 exceeds a preset length, and the width of the first pad 32 increases; the outer edge of the busbar welded to the bent back solder strip 22 is located inside the battery string 11, see [reference]. Figure 4 Preferably, the distance between the outer edge of the busbar and the edge of the second end B of the battery string 11 is greater than a preset second distance. The second distance can be set according to actual conditions, for example, 5mm to 25mm, such as 5mm, 10mm, 15mm, 20mm, or 25mm. The preset length can be set to a length greater than the second distance. When the second distance is 5mm to 25mm and the busbar width is 8mm to 12mm, the preset length can be set between 13mm and 40mm. This allows the welded busbar to be closer to the inner side of the battery string 11, away from the edge of the module during lamination, thereby reducing the pressure on the edge of the module during lamination, increasing the distance between the front solder strip 22 of the battery string 11 and the front glass after lamination, and improving the reliability of the module.

[0042] In one optional technical solution, the battery string 11 further includes a first transparent pad 33 adhered to the front side of the first end A of the battery string 11. In another optional technical solution, the battery string 11 further includes a first transparent pad 33 adhered to the front side of the first end A of the battery string 11, and a second transparent pad adhered to the front side of the second end B of the battery string 11, see [link to relevant documentation]. Figure 6 Transparent gaskets (including the first transparent gasket 33 and the second transparent gasket) are as follows: Figure 2 As shown, it uses an optically transparent pad material, which does not affect the light reception on the front of the battery string 11, and can also have a certain degree of pre-crosslinking (e.g., 8%-10%) to provide buffering and protection. For example, the transparent pad material can be EVA, EPE (Ethylene-Propylene Elastomer, a multilayer structural material), or other adhesive film materials. In practical applications, the transparent pad can be heated by a heating device to achieve bonding. Optionally, a heat insulation layer can be added inside the transparent pad to prevent interference with the solder strip below the transparent pad during busbar welding. For example, the length of the transparent pad can be consistent with the dimensions of the battery cell 1, and the width can be 10mm-25mm, such as 10mm, 15mm, 20mm, or 25mm.

[0043] By placing a transparent spacer between the front side of the battery string 11 and the front glass, the distance between the front solder strip 21 and the front glass can be increased, ensuring that there is enough adhesive film filling between the front solder strip 21 and the front glass, effectively reducing the pressure on the edges during lamination, thereby reducing the risk of microcracks in the battery cell 1 and glass breakage, and improving the reliability and yield of the module.

[0044] Figure 6 The arrangement of the battery string 11 at both ends, front and back, is shown. Figure 6 The left-middle figure shows the first insulating strip 31 arranged on the back of the first end A of the battery string 11 and the staggered folding of the front solder strip 21. Figure 6 The middle image shows a first transparent pad 33 arranged on the front of the first end A of the battery string 11. Figure 6 The right figure shows the arrangement of the first pad 32 on the back of the second end B of the battery string 11 and the staggered bending of the back solder strip 22.

[0045] In one embodiment, the battery string 11 further includes a central spacer 34, which is adhered to the back side of the middle portion of the battery string 11 to facilitate the welding of the busbars at corresponding positions to the back solder strips 22. See [link to relevant documentation]. Figure 7 The central spacer strip 34 can be made of transparent or opaque material, and can be made of insulating or non-insulating material. It can have a certain degree of pre-crosslinking (e.g., 8%-10%) to provide cushioning and protection. More preferably, the central spacer strip 34 is made of optically transparent material so as not to affect the light reception on the back of the battery string 11. Exemplarily, the material of the central spacer strip 34 can be EVA, EPE (Ethylene-Propylene Elastomer, a multilayer structural material) or other adhesive film materials. In practical applications, the central spacer strip 34 can be heated by a heating device to achieve bonding. Optionally, a heat insulation layer can be added inside the central spacer strip 34 so as not to affect the welding strip below the central spacer strip 34 when welding the busbar. Exemplarily, the length of the central spacer strip 34 can be consistent with the dimensions of the battery cell 1, and the width can be 10mm-25mm, such as 10mm, 15mm, 20mm, 25mm.

[0046] This utility model also provides a photovoltaic module, see [link to relevant documentation] Figures 1 to 6 The photovoltaic module includes the previously described photovoltaic cell strings 11 and a first busbar 41. Multiple cell strings 11 are arranged to form a cell array. The first busbar 41 is welded to the front solder strip 21 (after the back side is folded over) of the first end A of multiple cell strings 11 in the same column or row of the cell array, thereby connecting the multiple cell strings 11 in parallel. Exemplarily, to make the busbar more flexible and thus improve process yield, the first busbar 41 can be set as a tin-plated copper flat strip, and the width of the first busbar 41 can be set to 8mm-12mm. In some embodiments, the width of the first busbar 41 can be 8mm, 9mm, 10mm, 11mm, or 12mm. The thickness of the first busbar 41 can be set to 0.08mm-0.1mm. In some embodiments, the thickness of the first busbar 41 can be 0.08mm, 0.09mm, or 0.1mm.

[0047] Electromagnetic welding can be used to weld the busbar and the solder strip. However, electromagnetic welding requires contact and pressure, which may cause the battery cell to crack. Furthermore, the welding temperature is relatively high (e.g., around 300℃), resulting in thermal stress and a tendency for the weld to detach. To address this issue, a low-temperature lamination welding method can be used to weld the busbar and the solder strip.

[0048] Low-temperature lamination welding is performed during the stacking process after the battery string 11 is arranged. In the stacking process, busbars are placed on the back of the battery string 11. Then, a pressure-sensitive adhesive film 5 is placed on the surface of the busbars, and pressure is applied to the film 5 using a tooling to bond the busbars and solder strips together, thus fixing them and establishing ohmic contact. Subsequently, in the lamination process, the bonded busbars and solder strips are low-temperature welded together.

[0049] The temperature of the above-mentioned low-temperature welding is lower than that of electromagnetic welding. For example, the temperature range for the above-mentioned low-temperature welding is 143°C to 150°C. This low-temperature lamination welding method eliminates the thermal stress associated with high-temperature welding, reducing the likelihood of desoldering. Furthermore, the pressure-sensitive adhesive film, when pressurized by the tooling, ensures full contact between the busbar and the solder strip, thereby improving reliability. Additionally, the welding method is non-pressure welding, which reduces the likelihood of cell cracking during the welding process, thus improving process yield.

[0050] The pressure-sensitive adhesive film 5 described above can adhere to the surface of various substrates under certain pressure and is easy to peel off from the substrate. It has good heat resistance, weather resistance, and aging resistance. Its shape before pressure is shown in the figure. Figure 8 For example, the pressure-sensitive adhesive film 5 may be made of acrylic or polyurethane pressure-sensitive adhesive. Before being pressurized, the thickness of the pressure-sensitive adhesive film 5 may be 0.1 mm to 0.2 mm. In one embodiment, the width of the pressure-sensitive adhesive film 5 is greater than the width of the first spacer 32, for example, the width of the pressure-sensitive adhesive film is 10 mm to 20 mm greater than the width of the first spacer. The length of the pressure-sensitive adhesive film 5 is consistent with the busbar length required for the photovoltaic module layout. Preferably, the pressure-sensitive adhesive film 5 has multiple through holes 51, the positions of which correspond to each solder strip (for example, the pressure-sensitive adhesive film 5 has multiple through holes 51 in a row or column corresponding to each solder strip). These through holes 51 are used for flux evaporation during low-temperature lamination welding.

[0051] Preferably, when using low-temperature lamination soldering, the busbar can be made of a low-temperature material such as tin-lead-bismuth, with a melting range of 120-140°C. In one embodiment, the busbar can be pre-coated with flux or low-temperature solder paste to facilitate alloying between the busbar and the solder strip after low-temperature lamination soldering. In one embodiment, the tooling may include: a non-metallic part that contacts the pressure-sensitive adhesive film 5 and a metallic part that connects the non-metallic part. The metallic part can be made of steel, iron, or other metal materials, while the non-metallic part can be made of silicone or other non-metallic materials. Applying pressure by contacting the non-metallic part with the pressure-sensitive adhesive film 5 allows the contact surfaces of the tooling and the pressure-sensitive adhesive film 5 to adhere, which is beneficial for achieving sufficient contact and fixation between the busbar and the solder strip, while reducing the occurrence of chip breakage and improving yield.

[0052] In one embodiment, the photovoltaic module further includes a second busbar 42. Exemplarily, to make the busbar more flexible and thus improve process yield, the second busbar 42 can be set as a tin-plated copper flat strip, the width of the second busbar 42 can be set to 8mm-12mm, such as 8mm, 9mm, 10mm, 11mm, 12mm, and the thickness of the second busbar 42 can be set to 0.08mm-0.1mm, such as 0.08mm, 0.09mm, 0.1mm.

[0053] exist Figure 5 In the first embodiment shown for the second end B of the battery string 11, the back solder strip 22 of the second end B of the battery string 11 is located inside the second end B of the battery string 11 or flush with the edge of the second end B of the battery string 11. The first pad 32 is bonded to the back of the second end B of the battery string 11. The second busbar 42 is disposed on the first pad 32 of multiple second ends B of the battery strings 11 in the same column or row of the battery array, and the second busbar 42 is welded to the back solder strip 22 located below the first pad 32. In the above embodiment, the first pad 32 provides a buffer when the back solder strip 22 is welded to the second busbar 42, thereby improving the welding reliability and avoiding damage to the solder joint, cracking during welding, etc.

[0054] In one optional implementation of the first method described above, when the back solder strip 22 of the second end B of the battery string 11 is located inside the second end B of the battery string 11 or flush with the edge of the second end B of the battery string 11, the first pad 32 is perpendicular to the extension direction of the battery string 11, and the first pad 32 is provided with connection holes corresponding one-to-one with the back solder strip 22. The second busbar 42 is welded to the back solder strip 22 through the connection holes. In another optional implementation of the first method described above, the first pad 32 is perpendicular to the extension direction of the battery string 11, and the outer side of the first pad 32 is provided with equally spaced serrations with openings facing outwards from the battery string 11. The openings of the serrations correspond one-to-one with the back solder strip 22. The second busbar 42 is welded to the back solder strip 22 exposed at each serration opening of the first pad 32.

[0055] exist Figure 1 In the second embodiment shown for the second end B of the battery string 11, the portion of the back solder strip 22 extending beyond the edge of the second end B of the battery string 11 is bent on the back side of the second end B of the battery string 11. One surface of the first pad 32 is bonded to the back of the second end B of the battery string 11, and the other surface of the first pad 32 is bonded to the bent back solder strip 22. The second busbar 42 is welded to the bent back solder strip 22 of the second end B of multiple battery strings 11 in the same column or row of the battery array.

[0056] In the first and second methods described above for the second terminal B of the battery string 11, the busbar and the solder strip can be welded using electromagnetic welding or low-temperature lamination welding. In practical applications, electromagnetic welding requires contact and pressure, which may cause the battery cells to crack, and the welding temperature is relatively high (e.g., around 300°C), resulting in thermal stress and a tendency for desoldering. To address these issues, in a preferred embodiment, low-temperature lamination welding can be used to weld the busbar and the solder strip.

[0057] Low-temperature lamination welding is performed during the stacking process after the battery strings 11 are arranged. In this process, a second busbar 42 is placed on the back of the second end B of multiple battery strings 11 in the same column or row of the battery array. A pressure-sensitive adhesive film 5 is then placed on the surface of the second busbar 42, and pressure is applied to the film using a tool to bond the second busbar 42 to the back solder strip 22 based on the film. This fixes the busbar to the solder strip and establishes an ohmic contact between them. In practical applications, after applying pressure to the film 5 using a tool, the second busbar 42, the back solder strip 22, the first spacer strip 32, and the back of the battery cell 1 can be sequentially and tightly bonded and fixed based on the pressure-sensitive adhesive film 5. During the lamination process, the bonded second busbar 42 and the back solder strip 22 are low-temperature welded together.

[0058] The temperature of the above-mentioned low-temperature welding is lower than that of electromagnetic welding. For example, the temperature range for the above-mentioned low-temperature welding is 143°C to 150°C. This low-temperature lamination welding method eliminates the thermal stress associated with high-temperature welding, reducing the likelihood of desoldering. Furthermore, the pressure-sensitive adhesive film 5, when pressure is applied by the tooling, ensures sufficient contact between the busbar and the solder strip, thereby improving reliability. Additionally, the welding method is non-pressure welding, which reduces the likelihood of cell 1 cracking during the welding process, thus improving process yield.

[0059] The pressure-sensitive adhesive film 5 can adhere to the surface of various substrates under certain pressure and is easy to peel off from the substrate, exhibiting good heat resistance, weather resistance, and aging resistance. For example, the material of the pressure-sensitive adhesive film 5 can be acrylic or polyurethane pressure-sensitive adhesive, and the thickness of the pressure-sensitive adhesive film 5 can be 0.1mm to 0.2mm. In one embodiment, the width of the pressure-sensitive adhesive film 5 is greater than the width of the first spacer strip 32, for example, the width of the pressure-sensitive adhesive film is 10mm to 20mm greater than the width of the first spacer strip, and the length of the pressure-sensitive adhesive film 5 is consistent with the busbar length required by the photovoltaic module layout. More preferably, the pressure-sensitive adhesive film 5 has multiple through holes 51, the positions of which correspond to each solder strip (for example, the pressure-sensitive adhesive film 5 has multiple through holes 51 in a row or column corresponding to each solder strip), and these through holes 51 are used for flux evaporation during low-temperature lamination welding.

[0060] Preferably, when using low-temperature lamination soldering, the busbar can be made of a low-temperature material such as tin-lead-bismuth, with a melting range of 120-140°C. In one embodiment, the busbar can be pre-coated with flux or low-temperature solder paste to facilitate alloying between the busbar and the solder strip after low-temperature lamination soldering. In this embodiment, the tooling may include a non-metallic part that contacts the pressure-sensitive adhesive film 5 and a metallic part that connects the non-metallic part. The metallic part can be made of steel, iron, or other metal materials, while the non-metallic part can be made of silicone or other non-metallic materials. Applying pressure by contacting the non-metallic part with the pressure-sensitive adhesive film 5 allows the contact surfaces of the tooling and the pressure-sensitive adhesive film 5 to adhere, which is beneficial for achieving sufficient contact and fixation between the busbar and the solder strip, while reducing the occurrence of chip breakage and improving yield.

[0061] In an alternative technical solution, the photovoltaic module also includes a central busbar 43, see [link to technical solution]. Figure 7 The central busbar 43 is disposed on the central pad 34 and welded to the back solder strip 22 in the middle of the battery string 11. For example, to make the busbar more flexible and thus improve process yield, the central busbar 43 can be set as a tin-plated copper flat strip, with a width of 10mm-12mm (e.g., 10mm, 11mm, 12mm) and a thickness of 0.1mm-0.2mm (e.g., 0.1mm, 0.15mm, 0.2mm).

[0062] like Figure 7 As shown, the first busbar 41 is arranged on the first insulating strip 31 and hidden behind the first end A of the battery string 11; the second busbar 42 is arranged on the first pad strip 32 and hidden behind the second end B of the battery string 11; the middle busbar 43 is arranged on the middle pad strip 34 and hidden behind the middle position of the battery string 11. By hiding each busbar on the back, the busbars do not occupy the light-receiving area on the front of the module, thereby increasing the module power.

[0063] In summary, the embodiments of this utility model provide the following technical solutions:

[0064] Technical Solution 1: A photovoltaic cell string includes a cell 1, a solder strip, and a first insulating strip 31; the cell 1 is connected in series by the solder strip to form a cell string 11; the first insulating strip 31 is bonded to the back of the first end A of the cell string 11; the front solder strip 21 of the first end A of the cell string 11 extends out of the edge of the first end A of the cell string 11, and is folded to the back of the first end A of the cell string 11 and bonded to the first insulating strip 31.

[0065] Technical Solution 2: According to the photovoltaic cell string described in Technical Solution 1, the front welding strip 21 includes an original segment located on the front side of the first end A of the cell string 11 before folding and a folded segment located on the back side of the first end A of the cell string 11 after folding, wherein the original segment and the folded segment are offset.

[0066] Technical Solution 3: According to Technical Solution 1 or 2, in a photovoltaic cell string, the first insulating strip 31 is perpendicular to the extension direction of the cell string 11; the first insulating strip 31 is provided with equally spaced serrations on the side near the first end A of the cell string 11, with the openings facing the first end A of the cell string 11; the serration openings correspond one-to-one with the front solder strips 21, and the front solder strips 21 are folded at the bottom of the corresponding serration openings.

[0067] Technical Solution 4: A photovoltaic cell string according to Technical Solution 1 further includes a first spacer strip 32; the back welding strip 22 of the second end B of the cell string 11 is located inside the second end B of the cell string 11 or flush with the edge of the second end B of the cell string 11, and the first spacer strip 32 is bonded to the back of the second end B of the cell string 11; or, the portion of the back welding strip 22 of the second end B of the cell string 11 extending beyond the edge of the second end B of the cell string 11 is bent on the back side of the second end B of the cell string 11, one surface of the first spacer strip 32 is bonded to the back of the second end B of the cell string 11, and the other surface of the first spacer strip 32 is bonded to the bent back welding strip 22.

[0068] Technical Solution 5: According to Technical Solution 4, in a photovoltaic cell string, the back welding strip 22 of the second end B of the cell string 11 is located inside the second end B of the cell string 11 or is flush with the edge of the second end B of the cell string 11. The first pad 32 is perpendicular to the extension direction of the cell string 11, and the first pad 32 is provided with connecting holes corresponding one-to-one with the back welding strip 22; or, when the portion of the back welding strip 22 of the second end B of the cell string 11 extending beyond the edge of the second end B of the cell string 11 is bent on the back side of the second end B of the cell string 11, the back welding strip 22 includes an original segment before bending and a folded segment after bending, and the original segment and the folded segment are offset.

[0069] Technical Solution 6: A photovoltaic cell string according to Technical Solution 1 or 4 further includes a first transparent pad 33 adhered to the front side of the first end A of the cell string 11; or, it further includes a first transparent pad 33 adhered to the front side of the first end A of the cell string 11, and a second transparent pad adhered to the front side of the second end B of the cell string 11.

[0070] Technical Solution 7: A photovoltaic module, comprising a battery string 11 as described in any one of technical solutions 1-6 and a first busbar 41; a plurality of battery strings 11 are arranged to form a battery array, and the first busbar 41 is welded to the front solder strip 21 of the back side folded over the first end A of a plurality of battery strings 11 in the same column or row of the battery array.

[0071] Technical Solution 8: A photovoltaic module according to Technical Solution 7 further includes a second busbar 42; the back solder strip 22 of the second end B of the battery string 11 is located inside the second end B of the battery string 11 or flush with the edge of the second end B of the battery string 11; a first pad 32 is bonded to the back of the second end B of the battery string 11; the second busbar 42 is disposed on the first pad 32 of multiple second ends B of the battery strings 11 in the same column or row of the battery array; and the second busbar 42 is connected to the first pad 32 located on the first pad 32. The back solder strip 22 under strip 32 is welded; or, the portion of the back solder strip 22 of the second end B of the battery string 11 extending beyond the edge of the second end B of the battery string 11 is bent on the back side of the second end B of the battery string 11, one surface of the first pad strip 32 is bonded to the back of the second end B of the battery string 11, the other surface of the first pad strip 32 is bonded to the bent back solder strip 22, and the second busbar 42 is welded to the bent back solder strip 22 of the back of the second end B of the battery string 11 in the same column or row of the battery array.

[0072] Technical Solution 9: According to the photovoltaic module described in Technical Solution 7, one surface of the first busbar (41) is welded to the folded front welding strip (21), and a pressure-sensitive adhesive film (5) is also provided on the other surface.

[0073] Technical Solution 10: According to Technical Solution 8, a photovoltaic module is provided in which one surface of the second busbar (42) is welded to the back solder strip (22), and a pressure-sensitive adhesive film (5) is also provided on the other surface.

[0074] The specific embodiments described above do not constitute a limitation on the scope of protection of this utility model. 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 utility model should be included within the scope of protection of this utility model.

Claims

1. A photovoltaic cell string, characterized in that, Includes battery cells (1), solder strips, and a first insulating strip (31); The battery cells (1) are connected in series to form a battery string (11) via the solder strip; the first insulating strip (31) is bonded to the back of the first end (A) of the battery string (11); the front solder strip (21) of the first end (A) of the battery string (11) extends out of the edge of the first end (A) of the battery string (11), and is folded to the back of the first end (A) of the battery string (11) and bonded to the first insulating strip (31).

2. A photovoltaic cell string according to claim 1, characterized in that, The front welding strip (21) includes an original segment located on the front of the first end (A) of the battery string (11) before folding and a folded segment located on the back of the first end (A) of the battery string (11) after folding, wherein the original segment and the folded segment are offset.

3. A photovoltaic cell string according to claim 1 or 2, characterized in that, The first insulating strip (31) is perpendicular to the extending direction of the battery string (11); The first insulating strip (31) has serrations evenly distributed on the side near the first end (A) of the battery string (11) with the opening facing the first end (A) of the battery string (11); The serrated openings correspond one-to-one with the front welding strips (21), and the front welding strips (21) are folded at the bottom of the corresponding serrated openings.

4. A photovoltaic cell string according to claim 1, characterized in that, It also includes the first spacer strip (32); The back solder strip (22) of the second end (B) of the battery string (11) is located inside the second end (B) of the battery string (11) or flush with the edge of the second end (B) of the battery string (11), and the first pad strip (32) is bonded to the back of the second end (B) of the battery string (11). or, The portion of the back solder strip (22) of the second end (B) of the battery string (11) extending beyond the edge of the second end (B) of the battery string (11) is bent on the back side of the second end (B) of the battery string (11), one surface of the first pad (32) is bonded to the back side of the second end (B) of the battery string (11), and the other surface of the first pad (32) is bonded to the bent back solder strip (22).

5. A photovoltaic cell string according to claim 4, characterized in that, When the back solder strip (22) of the second end (B) of the battery string (11) is located inside the second end (B) of the battery string (11) or flush with the edge of the second end (B) of the battery string (11), the first pad (32) is perpendicular to the extension direction of the battery string (11), and the first pad (32) is provided with connection holes corresponding to the back solder strip (22). or, When the portion of the back solder strip (22) of the second end (B) of the battery string (11) extending beyond the edge of the second end (B) of the battery string (11) is bent on the back side of the second end (B) of the battery string (11), the back solder strip (22) includes an original segment before bending and a folded segment after bending, and the original segment and the folded segment are misaligned.

6. A photovoltaic cell string according to claim 1 or 4, characterized in that, It also includes a first transparent pad (33) that is adhered to the front side of the first end (A) of the battery string (11); or, It also includes a first transparent pad (33) adhered to the front of the first end (A) of the battery string (11), and a second transparent pad adhered to the front of the second end (B) of the battery string (11).

7. A photovoltaic module, characterized in that, Includes the battery string (11) as described in any one of claims 1-6 and the first busbar (41); Multiple battery strings (11) are arranged to form a battery array, and the first busbar (41) is welded to the front solder strip (21) of the back side folded after the multiple battery strings (11) in the same column or row of the battery array.

8. A photovoltaic module according to claim 7, characterized in that, It also includes the second busbar (42); The back solder strip (22) of the second end (B) of the battery string (11) is located inside the second end (B) of the battery string (11) or flush with the edge of the second end (B) of the battery string (11). The first pad (32) is bonded to the back of the second end (B) of the battery string (11). The second bus bar (42) is disposed on the first pad (32) of the second end (B) of multiple battery strings (11) in the same column or row in the battery array. The second bus bar (42) is welded to the back solder strip (22) located under the first pad (32). or, The portion of the back solder strip (22) of the second end (B) of the battery string (11) extending beyond the edge of the second end (B) of the battery string (11) is bent on the back side of the second end (B) of the battery string (11). One surface of the first pad (32) is bonded to the back side of the second end (B) of the battery string (11), and the other surface of the first pad (32) is bonded to the bent back solder strip (22). The second busbar (42) is welded to the bent back solder strip (22) of the second end (B) of the battery string (11) in the same column or row of the battery array.

9. A photovoltaic module according to claim 7, characterized in that, One surface of the first busbar (41) is welded to the folded front welding strip (21), and a pressure-sensitive adhesive film (5) is provided on the other surface.

10. A photovoltaic module according to claim 8, characterized in that, One surface of the second busbar (42) is welded to the back solder strip (22), and a pressure-sensitive adhesive film (5) is provided on the other surface.

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