Insulating film, battery assembly and photovoltaic system

Abstract

The utility model is applicable to the field of photovoltaic technology, and provides an insulating film, a battery assembly and a photovoltaic system, the insulating film comprises an insulating layer, and the insulating layer is provided with a first surface and a second surface which are oppositely arranged in the thickness direction; the first bonding layer is arranged on the first surface; the first bonding layer is arranged on the first surface, the second bonding layer is arranged on the second surface, the thickness of the first bonding layer is smaller than that of the second bonding layer, and the thickness of the whole insulating film is reduced, so that the thickness of a local position when the welding strip, the insulating film and the bus bar are stacked is reduced; specifically, according to the actual use requirement of the insulating film, on the premise that the insulating effect of the insulating film and the bonding reliability of the insulating film, a welding strip and a bus bar are not affected, the thicknesses of the bonding layers on the two sides of the insulating layer are designed in a differentiated mode, and the bonding reliability of the insulating film, the welding strip and the bus bar is improved. The thickness of the insulating film is effectively reduced on the basis of not losing the performance of the insulating film.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photovoltaic technology, and particularly relates to an insulating film, a battery assembly and a photovoltaic system. BACKGROUND

[0002] A solar cell, also known as a photovoltaic cell, is a device for directly converting light energy into direct current electricity by using photovoltaic effect. A PN junction on a semiconductor in the solar cell can directly convert solar energy into electrical energy by photovoltaic effect. The most common one is a crystalline silicon solar cell, including a single crystal silicon solar cell and a polycrystalline silicon solar cell. The solar cell is usually in a sheet shape.

[0003] In the related art, a plurality of cell sheets are connected in series by welding ribbons to form a cell string, the cell strings are connected by bus bars to form a battery assembly, the bus bars are installed on the back of the cell sheet, and an insulating film is arranged between the bus bar and the cell sheet to enable the bus bar to contact the same polarity welding ribbon on the cell sheet and to be insulated from the opposite polarity welding ribbon on the cell sheet. The welding ribbon, the insulating film and the bus bar are arranged in layers, and the local position of the overlapping area is too thick. During the lamination process of the photovoltaic assembly, stress concentration occurs in the overlapping area, which may further cause the phenomenon of cell sheet fragmentation or hidden cracks. CONTENT OF THE UTILITY MODEL

[0004] The application provides an insulating film, and aims to solve the problem that the welding ribbon, the insulating film and the bus bar are arranged in layers, the local position of the overlapping area is too thick, stress concentration occurs in the overlapping area during the lamination process of the photovoltaic assembly, and the phenomenon of cell sheet fragmentation or hidden cracks may occur.

[0005] In a first aspect, the application provides an insulating film, which comprises an insulating layer, the insulating layer has a first surface and a second surface arranged oppositely in the thickness direction; a first adhesive layer is arranged on the first surface; and a second adhesive layer is arranged on the second surface, and the thickness of the first adhesive layer is less than the thickness of the second adhesive layer.

[0006] The application reduces the thickness of the insulating film as a whole, thereby reducing the thickness of the local position when the welding ribbon, the insulating film and the bus bar are arranged in layers, and further reducing the risk of hidden cracks of the cell sheet during the lamination process of the photovoltaic assembly. Specifically, according to the actual use requirement of the insulating film, the thicknesses of the adhesive layers on both sides of the insulating layer are designed differently without affecting the insulating effect of the insulating film and the bonding reliability of the insulating film, the welding ribbon and the bus bar, that is, the thickness of the first adhesive layer is less than the thickness of the second adhesive layer. The first adhesive layer can be applied to a substrate with low bonding strength requirement, and the second adhesive layer can be applied to a substrate with high bonding strength requirement. The thickness of the insulating film is effectively reduced without losing the performance of the insulating film.

[0007] Optionally, a ratio of the thickness of the second adhesive layer to the thickness of the first adhesive layer is greater than or equal to 1.5 and less than or equal to 10.

[0008] Optionally, the thickness of the insulation film is greater than or equal to 120 μm and less than or equal to 250 μm.

[0009] Optionally, the thickness of the first adhesive layer is 30-60 μm.

[0010] Optionally, the thickness of the second adhesive layer is 80-120 μm.

[0011] Optionally, the thickness of the insulation layer is 25-50 μm.

[0012] Optionally, the first adhesive layer comprises an EVA layer, and / or the second adhesive layer comprises an EVA layer.

[0013] Optionally, the insulation layer comprises a PET layer.

[0014] In a second aspect, a battery assembly comprises the above-mentioned insulation film; a plurality of battery pieces; a solder strip extending along a first direction to connect two adjacent battery pieces; and a busbar extending along a second direction and crossing the solder strip, the insulation film being arranged between the solder strip and the busbar, and the insulation film and the busbar being arranged in the same direction.

[0015] Optionally, the first adhesive layer of the insulation film is connected to the busbar, and the second adhesive layer of the insulation film is connected to the solder strip and the battery pieces.

[0016] Optionally, the two adjacent battery pieces are arranged to partially overlap each other.

[0017] In a third aspect, a photovoltaic system comprises the above-mentioned battery assembly. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a structural schematic diagram of an insulation film provided in the present application;

[0019] Figure 2 is a structural schematic diagram of a battery assembly provided in the present application.

[0020] REFERENCE SIGNS

[0021] 100, insulation film; 101, insulation layer; 102, first adhesive layer; 103, second adhesive layer; 104, first surface; 105, second surface; 200, battery piece; 300, solder strip; 400, busbar. DETAILED DESCRIPTION

[0022] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. The examples of the embodiments are shown in the drawings, wherein identical or similar labels denote identical or similar elements or elements having identical or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only and are merely intended to explain the present application, and are not to be understood as limiting the present application. In addition, it should be understood that the specific embodiments described herein are merely intended to explain the present application and are not intended to limit the present application.

[0023] In the description of the present application, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are merely intended to facilitate the description of the present application and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0024] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0025] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0026] In the present application, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the second feature can include the direct contact of the first and second features, or can include the contact of the first and second features through another feature between them. Moreover, the "upper", "upper" and "upper" of the first feature to the second feature include the vertical direction of the first feature above and obliquely above the second feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The "below", "below" and "below" of the first feature to the second feature include the vertical direction of the first feature below and obliquely below the second feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0027] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplification, the components and arrangements of particular examples are described in the following disclosure. Of course, they are merely examples and are not intended to limit the present application. Moreover, the present application can repeatedly refer to reference numerals and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, which does not indicate the relationship between the various embodiments and / or arrangements discussed. In addition, the present application provides various specific examples of processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0028] As shown in Figure 1 In an embodiment of the present application, an insulating film 100 includes an insulating layer 101, a first adhesive layer 102 and a second adhesive layer 103. The insulating layer 101 has a first surface 104 and a second surface 105 arranged oppositely in the thickness direction, the first adhesive layer 102 is arranged on the first surface 104, and the second adhesive layer 103 is arranged on the second surface 105. The thickness of the first adhesive layer 102 is less than the thickness of the second adhesive layer 103. The insulating layer 101 mainly plays an insulating role, and is used to isolate the electrical conduction of the bus bar 400 and the welding strip 300. The first adhesive layer 102 and the second adhesive layer 103 mainly play an adhesive role. The first adhesive layer 102 can be used to bond with the bus bar 400, and the second adhesive layer 103 can be used to bond with the battery piece 200 and the welding strip 300, thereby realizing the fixed connection of the insulating film 100 between the battery piece 200 and the bus bar 400.

[0029] It should be noted that the researchers found that the insulating film is arranged between the battery piece and the bus bar, which plays a role in bonding, i.e. bonding and fixing the bus bar on the battery piece, and plays a role in closing the edge of the welding strip, preventing external factors such as moisture and oxygen from entering the inside of the solar cell, thereby prolonging the service life of the battery. In this way, if the bonding layer is too thin, it may not provide sufficient sealing effect, resulting in a decrease in battery performance. Since the welding strip itself has a certain thickness, the welding strip is arranged on the battery piece, and the bonding layer needs to cover and wrap the welding strip when combined with the battery piece to achieve full contact between the other parts of the bonding layer and the battery piece. In this application, the second bonding layer needs to have a large thickness, and the thickness of the second bonding layer is greater than the thickness of the welding strip. This is a problem that can be easily overlooked by those skilled in the art and is not seen, so it is difficult to improve the structure of the insulating film. Based on this conclusion, the researchers made different improvements to the bonding layers on both sides of the insulating layer, and set the thickness of the second bonding layer of the insulating layer towards the battery piece to be larger, so that the second bonding layer can wrap the welding strip after hot melting and be bonded and fixed on the battery piece. The thickness of the first bonding layer away from the battery piece is set to be smaller, and the first bonding layer only plays a role in bonding and fixing the bus bar, and the first bonding layer can be thinned compared to the second bonding layer, thereby thinning the entire insulating film and reducing the risk of hidden cracking of the battery piece.

[0030] Further, when the bonding layer is too thick, it may cause uneven bonding or air bubbles, thereby reducing the bonding strength. On the contrary, if the bonding layer is too thin, it may not provide sufficient bonding area and strength, resulting in a decrease in bonding performance. Therefore, in the embodiments of the present application, the thickness of the first bonding layer 102 is 30-60 μm. In such embodiments, the thickness of the first bonding layer 102 can be 30 μm, 40 μm, 50 μm, 60 μm or any value between 30 μm and 60 μm, which is not limited herein. Preferably, the thickness of the first bonding layer 102 is 40-50 μm, and within this range, the thickness of the first bonding layer 102 can be thinned to provide stronger bonding force and durability, ensuring the bonding strength of the insulating film and the substrate, and the substrate will not fall off. Exemplarily, the first bonding layer 102 can be bonded and combined with the bus bar 400 to ensure that the bus bar 400 is stably connected to the insulating film 100.

[0031] The thickness of the second adhesive layer 103 is 80-120 μm. In such embodiments, the thickness of the second adhesive layer 103 can be 80 μm, 90 μm, 100 μm, 110 μm, 120 μm or any value between 80-120 μm, which is not limited herein. Preferably, the thickness of the second adhesive layer 103 is 100-120 μm. Within this range, the second adhesive layer 103 can provide strong adhesion and durability after hot melting. Also, the thicker second adhesive layer 103 can completely wrap the solder strip 300 after hot melting, achieving complete contact between the second adhesive layer and the battery sheet 200, strengthening the connection strength between the insulation film 100, the solder strip 300 and the battery sheet 200, and the second adhesive layer 103 can play a buffering role during lamination, which is conducive to reducing the risk of hidden cracks of the battery sheet 200 during lamination. In addition, it should be noted that the second adhesive layer 103 with a certain thickness can improve the adhesion between the second adhesive layer 103 and the substrate, but when the thickness of the second adhesive layer 103 exceeds a certain range, the adhesion between the second adhesive layer 103 and the substrate tends to be stable, and the cost is increased, and the second adhesive layer 103 with excessive thickness will overflow into the gap between the solder strip and the battery sheet during high-temperature dissolution, causing the problem of virtual welding of the solder strip. The selected range of the embodiments of the present application is the preferred option.

[0032] In the embodiments of the present application, the thickness of the insulation film is greater than or equal to 120 μm and less than or equal to 250 μm. In such embodiments, the thickness of the insulation film can be 120 μm, 130 μm, 180 μm, 200 μm, 250 μm or any value between 120-250 μm, which is not limited herein. Preferably, the thickness of the insulation film is greater than or equal to 200 μm and less than or equal to 250 μm. Within this range, the risk of hidden cracks of the battery sheet during lamination can be effectively reduced.

[0033] It should be noted that the thickness of the insulation film 100 cannot be too thick or too thin. If the insulation film 100 is too thin, it is not convenient to operate during pasting, and it is easy to deform when pulled, and there is a risk of damage to long-term insulation. If it is too thick, it will increase the height difference, and the stress generated during lamination will be large, which will easily cause the battery sheet to crack and increase the risk of virtual welding. By setting the thickness of the insulation layer 101, the first adhesive layer 102 and the second adhesive layer 103, the overall thickness of the insulation film 100 can be controlled within a suitable range, achieving good insulation of the insulation film 100.

[0034] The application reduces the risk of cell 200 cracking during the lamination process of the photovoltaic module by reducing the thickness of the local position when the solder strip 300, the insulating film 100 and the bus bar 400 are stacked. Specifically, according to the actual use requirements of the insulating film 100, without affecting the insulation effect of the insulating film 100 and the bonding reliability of the insulating film 100 and the solder strip 300 and the bus bar 400, the thickness of the bonding layer on both sides of the insulating layer 101 is designed differently, that is, the thickness of the first bonding layer 102 is less than the thickness of the second bonding layer 103. The first bonding layer 102 can be applied to the substrate with low bonding strength requirement, and the second bonding layer 103 can be applied to the substrate with high bonding strength requirement. The thickness of the insulating film 100 is effectively reduced without losing its performance.

[0035] In some embodiments, the ratio of the thickness of the second bonding layer 102 to the thickness of the first bonding layer 103 is greater than or equal to 1.5 and less than or equal to 10. In such embodiments, the ratio of the thickness of the second bonding layer 102 to the thickness of the first bonding layer 103 can be 1.5, 2, 3, 4, 5, 7, 8, 9, 10 or any value between 1.5 and 10, which is not limited here. Different substrates have different requirements for the thickness of the bonding layer. Within this range, the thickness of the two bonding layers can be adjusted according to the specific substrate to meet different application requirements.

[0036] In some embodiments, the thickness of the insulating layer 101 is 25-50 μm. In such embodiments, the thickness of the insulating layer 101 can be 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm or any value between 25 and 50 μm, which is not limited here. Within this thickness range, the insulating layer 101 can effectively isolate the electrical conduction of the bus bar 400 and the solder strip 300, ensuring the normal operation and safety of the cell 200. In addition, the thicker insulating layer 101 can also prevent the burr on the edge of the solder strip 300 from piercing, further reducing the risk of short circuit of the cell 200.

[0037] In some embodiments, the first adhesive layer 102 includes an EVA layer, and / or the second adhesive layer 103 includes an EVA layer. The EVA layer, or ethylene-vinyl acetate copolymer layer, has excellent adhesive properties. As an adhesive layer, the EVA layer can effectively bond different materials together to form a unified structure. The EVA layer also has high light transmittance, ensuring that light passes through smoothly without reducing transmittance due to the presence of the adhesive layer. In photovoltaic modules, the high light transmittance of the EVA layer ensures that the solar panel receives maximum light, thereby improving power generation efficiency. In other embodiments, the first adhesive layer 102 and the second adhesive layer 103 may also include a PU (polyurethane) layer, a PVB (polyvinyl butyral) layer, etc., and this application does not impose any limitations on this.

[0038] In some embodiments, the insulating layer 101 includes a PET layer. The PET layer (polyethylene terephthalate) has high insulation resistance and dielectric strength, effectively isolating current and preventing current leakage or short circuits. In other embodiments, the insulating layer 101 may also include a polymethyl methacrylate (PMMA) layer, a polyethylene naphthalate (PEN) layer, or a polycarbonate (PC) layer, etc., and this application is not limited thereto.

[0039] like Figure 2 As shown, a battery assembly includes the aforementioned insulating film 100, multiple battery cells 200, solder ribbons 300, and busbars 400. The solder ribbons 300 connect adjacent battery cells 200. The insulating film 100 is located on the side of the solder ribbons 300 facing away from the battery cells 200, and the busbars 400 are disposed on the side of the insulating film 100 facing away from the battery cells 200. Specifically, the multiple solder ribbons 300 extend along a first direction to connect adjacent battery cells 200 to form a battery string, and the busbars 400 extend along a second direction to connect adjacent battery strings. The busbars extend along the second direction and intersect with the solder ribbons. The insulating film 100 and the busbars 400 extend in the same direction, and the insulating film completely isolates the busbars and the irregularly shaped solder ribbons. Understandably, the width of the insulating film 100 is greater than the width of the busbar 400. If the width of the insulating film 100 is too narrow, the busbar 400 will be exposed, which may result in a short circuit due to the busbar 400 coming into contact with the dissimilar electrode area or the dissimilar solder strip 300.

[0040] In the embodiment of the present application, the first adhesive layer 102 of the insulating film 100 is connected with the bus bar 400, and the second adhesive layer 103 of the insulating film 100 is connected with the battery piece 200 and the solder strip 300. Since the insulating film 100 needs to be bonded and combined with the battery piece 200 and the solder strip 300, a larger bonding strength is required to ensure that the insulating film 100 is stably connected to the battery piece 200 and the solder strip 300, and therefore the second adhesive layer 103 of the insulating film 100 is connected with the battery piece 200 and the solder strip 300, the thickness of the second adhesive layer 103 is greater than that of the first adhesive layer 102, and the second adhesive layer 103 can realize the fastening bonding of the insulating film 100, the battery piece 200 and the solder strip 300 after lamination melting. On the basis of the fastening connection of the insulating film 100, the battery piece 200 and the solder strip 300, the other side of the insulating film 100 only needs a lower bonding strength to realize the fixed connection of the bus bar 400, and therefore the first adhesive layer 102 of the insulating film 100 is connected with the bus bar 400 to ensure that the bus bar 400 will not deviate. In the embodiment of the present application, even if the local part of the insulating film 100 is thinned, the reliability of the overall performance of the insulating film 100 can still be ensured.

[0041] The two adjacent battery pieces 200 are partially overlapped. A plurality of battery pieces 200 are partially overlapped to form a battery string, and the contact area between the overlaps is not conductively connected, that is, no conductive glue or other adhesive glue is needed between the overlap areas, and the battery pieces 200 are only overlapped together. Among them, the overlap area of the adjacent battery pieces 200 in the battery string is provided with a solder strip 300 to fixedly connect the adjacent battery pieces 200. In this way, there is no gap between the battery pieces 200 and the battery pieces 200, so that the solder strip 300 can be better hidden, and the size of the battery string can be reduced by the overlapping arrangement of the battery pieces 200, thereby making the occupied space of the battery string smaller. Or, in the case of a certain size of the battery string, more battery pieces 200 can be placed, the power of the battery string is improved, and the cost per watt is reduced.

[0042] In the shingled battery assembly, the overlap area of the battery piece 200 is particularly vulnerable, and the thickness reduction of the insulating film 100 can significantly reduce the risk of hidden cracking of the battery piece 200 during lamination. Without affecting the reliability of the insulating film 100, the thickness of each film layer of the insulating film 100 is optimized by analyzing the bonding strength requirement of the insulating film 100 and other substrates, thereby improving the problem of hidden cracking of the battery piece 200 during lamination.

[0043] It can be understood that the partial overlap of the plurality of battery pieces 200 in the battery string refers to that the adjacent battery pieces 200 in the battery string overlap a part of area. Exemplarily, the overlap width range can be 0 millimeter to 0.5 millimeter, such as 0 millimeter, 0.1 millimeter, 0.2 millimeter, 0.4 millimeter or 0.5 millimeter, which is not limited in the present application.

[0044] A photovoltaic system comprising the above battery assembly. In the present embodiment, the photovoltaic system can be applied in a photovoltaic power station, such as a ground power station, a roof power station, a water surface power station, etc., and can also be applied in a device or apparatus utilizing solar energy for power generation, such as a user solar power source, a solar street lamp, a solar car, a solar building, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be applied in all fields requiring solar energy for power generation. Taking a photovoltaic power generation system network as an example, the photovoltaic system can comprise a photovoltaic array, a combiner box and an inverter, the photovoltaic array can be an array combination of a plurality of battery assemblies, for example, a plurality of battery assemblies can form a plurality of photovoltaic arrays, the photovoltaic arrays are connected to the combiner box, the combiner box can combine the currents generated by the photovoltaic arrays, the combined currents flow through the inverter to be converted into alternating current required by a power grid, and then are connected to a power network to realize solar power supply.

[0045] In the description of the present specification, the description referring to the terms "some embodiments", "exemplary embodiments", "examples", "specific examples", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0046] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An insulating film, characterized by, The insulating layer has a first surface and a second surface arranged oppositely in a thickness direction; a first adhesive layer arranged on the first surface; A second adhesive layer arranged on the second surface, the thickness of the first adhesive layer is less than the thickness of the second adhesive layer.

2. The insulating film according to claim 1, wherein The ratio of the thickness of the second adhesive layer to the thickness of the first adhesive layer is greater than or equal to 1.5 and less than or equal to 10.

3. The insulating film according to claim 1, wherein The thickness of the insulating film is greater than or equal to 120 μm and less than or equal to 250 μm.

4. The insulating film according to claim 1, wherein The thickness of the first adhesive layer is 30-60 μm.

5. The insulating film according to claim 1, wherein The thickness of the second adhesive layer is 80-120 μm.

6. The insulating film according to claim 1, wherein The thickness of the insulating layer is 25-50 μm.

7. The insulating film according to claim 1, wherein The first adhesive layer comprises an EVA layer, and / or the second adhesive layer comprises an EVA layer.

8. The insulating film according to claim 1, wherein The insulating layer comprises a PET layer.

9. A battery assembly characterized by, The insulating film according to any one of claims 1-8; a plurality of battery pieces; a solder strip extending along a first direction to connect two adjacent battery pieces; a bus bar extending along a second direction and arranged crosswise to the solder strip, the insulating film is arranged between the solder strip and the bus bar, and the insulating film and the bus bar are arranged in the same direction.

10. The battery assembly of claim 9, wherein, The first adhesive layer of the insulating film is connected to the bus bar, and the second adhesive layer of the insulating film is connected to the solder strip and the battery piece.

11. The battery assembly of claim 9, wherein, Two adjacent battery pieces are arranged partially overlapped.

12. A photovoltaic system characterized by, The battery assembly according to any one of claims 9-11.

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