Photovoltaic module and photovoltaic power generation device

Abstract

Photovoltaic module, comprehensive: a battery string, wherein the battery string comprises a plurality of solar cells and a plurality of conductive connectors, wherein two adjacent solar cells are electrically connected to each other via the plurality of conductive connectors; and an encapsulation layer, wherein the encapsulation layer is attached to the battery string; wherein a plurality of bonding units are provided between the encapsulation layer and the battery string, the plurality of bonding units being designed to connect the plurality of conductive connectors on the plurality of solar cells; a characteristic value R satisfies the following formula (1): R = | n2 − n1 | 1 2 ( n1 + n2 ); a characteristic value Y satisfies the following formula (2): Y = h H , where the characteristic value R lies in a range from 0.014 to 0.118; n1 represents a refractive index of the multitude of bonding units for light; n2 represents the refractive index of the encapsulation layer for light; the characteristic value Y is less than or equal to 0.9; H represents the thickness of the encapsulation layer; h represents the height of each of the multiple bonding units; and The height of each of the multiple bonding units is in a range of 50 µm to 280 µm.

Description

CROSS-REFERENCE TO RELATED REGISTRATION

[0001] This application claims priority from Chinese patent application No. 202411784867.0, filed on December 6, 2024 and entitled “PHOTOVOLTAIC MODULE, METHOD FOR THIS AND PHOTOVOLTAIC POWER GENERATION DEVICE”. TECHNICAL AREA

[0002] The present application relates to the field of photovoltaic technology and in particular to a photovoltaic module and a photovoltaic power generation device. STATE OF THE ART

[0003] A metal electrode on the front and back of a solar cell are used to conduct an internal current and can be divided into busbars and fingers (i.e., fine grids). The busbars primarily serve to collect the current from the fingers and connect them in series, while the fingers are used to collect photogenerated charge carriers. Gate routing patterns have evolved from the earlier 4BB (busbar) and 5BB (busbar) configurations to MBB (multiple busbars including 9-15 grids) and then, in recent years, to the common SMBB technology (super multi-busbar including 16 grids or more). Adhesive bonded photovoltaic module technology represents a further development of SMBB technology and has gradually become one of the current research priorities and development trends.

[0004] Adhesives, as a key material used in bonded photovoltaic module technology, have received considerable attention. Common adhesives are primarily categorized as silicone, acrylic, or epoxy resin systems. The adhesive's properties, such as adhesion strength, resistance to yellowing, and hardness, significantly influence the performance of a photovoltaic module and are factors to consider during the development of the relevant technology. In the actual research, development, and production testing process, factors such as print quality, the number and size of adhesive dots, and similar considerations also affect the reliability of a photovoltaic module.For example, deformation of the adhesive points, a reduction in the number of adhesive points, and the size of the adhesive points can easily lead to insufficient adhesive strength, thus affecting the yield of the photovoltaic module.

[0005] For this reason, the present invention is proposed. SUMMARY

[0006] The present application provides a photovoltaic module, a method for it and a photovoltaic power generation device, with the intention of improving the performance of the photovoltaic module while ensuring the yield of the photovoltaic module and also increasing the aesthetic appearance of the photovoltaic module.

[0007] The present application will be implemented as follows.

[0008] In a first aspect, the present application provides a photovoltaic module. The photovoltaic module comprises a battery string and an encapsulation layer. The battery string comprises a plurality of solar cells and a plurality of conductive connectors. Two adjacent members of the plurality of solar cells are electrically connected to each other via the plurality of conductive connectors. The encapsulation layer is attached to the battery string. The plurality of bonding units is provided between the encapsulation layer and the battery string. The plurality of bonding units is designed to connect the plurality of conductive connectors on the plurality of solar cells. A characteristic value R satisfies the following formula (1): R=|n2−n1|12(n1+n2). A characteristic value Y satisfies the following formula (2): Y=hH. The characteristic value R lies in the range of 0.014 to 0.118. n1 represents the refractive index of the multitude of bonding units for light. n2 represents the refractive index of the encapsulation layer for light. The characteristic value Y is less than or equal to 0.9. H represents the thickness of the encapsulation layer. h represents the height of each of the multitude of bonding units.

[0009] In some embodiments, the characteristic value R lies in a range from 0.02 to 0.097.

[0010] In some embodiments, the refractive index n1 of the plurality of bonding units for light is smaller than the refractive index n2 of the encapsulation layer for light.

[0011] In some embodiments, the multitude of bonding units are arranged on at least one surface of the battery string. Alternatively, the multitude of bonding units are formed by the curing of an adhesive.

[0012] In some embodiments, the refractive index n1 of the plurality of bonding units for light is in the range of 1.35 to 1.60. The height of each of the plurality of bonding units is in the range of 50 µm to 280 µm. Alternatively, the adhesive designed to form the plurality of bonding units is selected from the group consisting of an organic silicone adhesive, an acrylic adhesive, an epoxy resin adhesive, and any combination thereof.

[0013] In some embodiments, the refractive index n2 of the encapsulation layer for light is in the range of 1.40 to 1.65. The thickness of the encapsulation layer is in the range of 300 µm to 400 µm. Alternatively, the encapsulation layer is formed by laminating and crosslinking an encapsulation adhesive film. The encapsulation adhesive film is selected from the group consisting of an encapsulation adhesive film made of polyolefin elastomer, an encapsulation adhesive film made of ethylene vinyl acetate copolymer, an encapsulation adhesive film of a coextruded product with polyolefin elastomer and ethylene vinyl acetate copolymer, and any combination thereof.

[0014] In some embodiments, gray values ​​of different areas of the photovoltaic system are captured by a camera to record a surface of the photovoltaic module, allowing a characteristic value G to be calculated. The characteristic value G follows the formula: G=|g2−g1|, where the characteristic value G represents a threshold value of the gray value, g1 represents a gray value of a portion of the photovoltaic module's surface without the multiple bonding units, and g2 represents a gray value of another portion of the photovoltaic module's surface with the multiple bonding units. The characteristic value G is less than or equal to 20.

[0015] In some embodiments, a surface of each of the plurality of conductive connectors at a position where the plurality of bonding units is located is enclosed by each of the plurality of bonding units.

[0016] In some embodiments, at a position where the plurality of bonding units is located, each of the plurality of bonding units is arranged between each of the plurality of conductive connectors and each of the plurality of solar cells, with a portion of a surface of each of the plurality of conductive connectors being covered by each of the plurality of bonding units.

[0017] In some embodiments, both the plurality of conductive connectors and the plurality of bonding units are provided on a front side of each of the plurality of solar cells and on a rear side of each of the plurality of solar cells; the encapsulation layer comprises a front adhesive film and a rear adhesive film; the front adhesive film is attached to a front side of the battery string, the rear adhesive film is attached to a rear side of the battery string.

[0018] In some embodiments, the photovoltaic module fulfills at least one of the following conditions: The characteristic value R lies in a range from 0.014 to 0.118; The ratio Y of the height of each of the multiple bonding units to the thickness of the front adhesive film is less than or equal to 0.9. In some embodiments, the multitude of conductive connectors are ribbons.

[0019] In some embodiments, the plurality of solar cells are arranged at a distance from one another. A surface of one of the plurality of solar cells is connected to another opposite surface of a neighboring plurality of solar cells.

[0020] In some embodiments, the photovoltaic module further comprises a front protective substrate and a rear protective substrate. The front protective substrate is attached to an end face of the front adhesive film facing away from the battery string. The rear protective substrate is attached to an end face of the rear adhesive film facing away from the battery string.

[0021] In some embodiments, the front protective substrate consists of glass. Alternatively, the rear protective substrate consists of at least one of the materials glass and high-molecular-weight polymer. The high-molecular-weight polymer includes polyethylene terephthalate, polyolefin copolymer, polyamide, polyvinyl fluoride, and polyvinylidene fluoride.

[0022] In a second aspect, a manufacturing method for the photovoltaic module in the above embodiments of the present application is provided. The method comprises arranging a plurality of conductive connectors on at least one surface of a plurality of solar cells along a thickness direction of each of the plurality of solar cells, connecting the plurality of conductive connectors to the plurality of solar cells by means of a plurality of bonding units to form a battery string, and encapsulating the battery string with an encapsulation layer of the photovoltaic module. A characteristic value R satisfies the following formula (1): R=|n2−n1|12(n1+n2). A characteristic value Y satisfies the following formula (2): Y=hH.n1 n1 represents the refractive index of the multitude of bonding units for light. n2 represents the refractive index of the encapsulation layer for light. The characteristic value R lies in the range of 0.014 to 0.118 by adjusting the refractive index n1 of the multitude of bonding units for light and the refractive index n2 of the encapsulation layer for light. H represents the thickness of the encapsulation layer. h represents the height of each of the multitude of bonding units. The characteristic value Y is less than or equal to 0.9 by adjusting the thickness H of the encapsulation layer and the height h of each of the multitude of bonding units.

[0023] In some embodiments, arranging the plurality of conductive connectors on the at least one surface of the plurality of solar cells along the thickness direction of each of the plurality of solar cells, connecting the plurality of conductive connectors to the plurality of solar cells by means of a plurality of bonding units to form a battery string, further comprises: arranging the plurality of solar cells along a first direction, arranging a fine grid line of each of the plurality of solar cells along a second direction, and arranging the plurality of conductive connectors along the first direction when the plurality of conductive connectors are mounted. The first direction intersects the second direction. The battery string is produced by applying an adhesive for fixation and subsequent welding.Alternatively, the battery string is manufactured by welding and then applying an adhesive for fixation.

[0024] In some embodiments, the characteristic value R lies in a range from 0.02 to 0.097.

[0025] In some embodiments, the refractive index n1 of the plurality of bonding units for light is smaller than the refractive index n2 of the encapsulation layer for light.

[0026] In a third aspect, a photovoltaic power generation device is provided. The photovoltaic power generation device comprises the photovoltaic module according to one of the above embodiments or a photovoltaic module obtained by the method of one of the above embodiments.

[0027] The number of photovoltaic modules is M, M photovoltaic modules are connected in series, where M is an integer that is at least 1.

[0028] The present application offers the following advantages. In this application, the refractive index of the plurality of bonding units for light, the refractive index of the encapsulation layer for light, the thickness of the encapsulation layer, and the height of each of the plurality of bonding units are adapted. When light enters the plurality of bonding units from the encapsulation layer, the intensity R of the refracted light is in the range of 0.014 to 0.118, so that very little incident light is reflected at an interface between the plurality of bonding units and an adhesive film.The ratio Y of the height of each of the multiple bonding units to the thickness of the encapsulation layer is less than 0.9. This prevents the formation of bubbles between, or within, the multiple bonding units and the encapsulation layer, thus improving the utilization rate of incident light and increasing the performance of the photovoltaic module. The contour of each of the multiple bonding units is not visible upon visual inspection of the laminated photovoltaic module, and its contour is concealed within the encapsulation layer, thereby enhancing the aesthetic appearance of the photovoltaic module.In the present application, the number of the plurality of bonding units and the size of each of the plurality of bonding units can be kept at an original level without reducing the adhesive strength of the adhesive, thereby ensuring the yield of the photovoltaic module.

[0029] In the related technology, more emphasis was placed on the bonding stability of a multitude of bonding units, without considering the issue of how the presence of the multitude of bonding units (such as adhesive dots) can affect the aesthetics of the photovoltaic module, and without considering how the contour of the bonding unit can be made invisible during visual inspection. According to the invention, the inventor controls the refractive index of the multitude of units for light and the refractive index of the encapsulation layer for light such that the refractive index of the multitude of units for light and the refractive index of the encapsulation layer for light have a specific relationship, thereby achieving the technical effect that the contour of the multitude of bonding units is not visible during visual inspection.

[0030] Furthermore, the inventor notes that even when the characteristic value is in the range of 0.014 to 0.118, the adhesive dot may be visible during visual inspection. Based on magnified test results, the inventor surmised that the aforementioned situation is caused by a bubble on the multitude of bonding units or at the interface between the multitude of bonding units and the adhesive film. If the bubble occurs on the surface of the multitude of bonding units or within the multitude of bonding units, the intensity of the reflected light at the interface between the multitude of bonding units and the bubble increases significantly, making the adhesive dots visible during visual inspection, which in turn impairs the aesthetics of the photovoltaic module.Furthermore, the inventor recognized that the height of each of the multiple bonding units and the thickness of the encapsulation layer have a significant influence on the bubble formed in the photovoltaic module. The inventor adjusted the thickness of the encapsulation layer and the height of the multiple bonding units to a specific ratio to ensure that the contour of the multiple bonding units is not visible during visual inspection. Based on the foregoing, the inventor unexpectedly finds that the photovoltaic module produced according to the present invention can further improve the performance of the photovoltaic module while the contour of the multiple bonding units remains invisible during visual inspection.

[0031] In some embodiments, according to the invention, the refractive index n1 of the plurality of bonding units for light is smaller than the refractive index n2 of the encapsulation layer for light. The light entering the bonding unit from the front adhesive film or the rear adhesive film is defined as light entering the light-poor medium from the light-tight medium, and the refracted light will move away from the perpendicular, thereby allowing more incident light to reach the surface of the plurality of solar cells, thus improving the performance of the photovoltaic module. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To provide a clearer explanation of the technical solutions to embodiments of the present application, a brief introduction to the accompanying drawings required for these embodiments is given. It is understood that the following drawings merely illustrate certain embodiments of the present application and are not to be considered as limiting the scope of protection of the present application. Those skilled in the art can derive further relevant drawings from these drawings without inventive step. Fig. Figure 1 is a schematic cross-sectional representation of a dot of adhesive completely encasing a tape. Fig. Figure 2 is a partially schematic representation of a battery string. Fig. Figure 3 is a schematic representation of a photovoltaic module in one embodiment. Fig.Figure 4 is a partially schematic representation of a photovoltaic module in one embodiment. Fig. Figure 5 is a schematic representation of the propagation of incident light where the refractive index n1 of a plurality of bonding units for light is smaller than the refractive index n2 of an encapsulation layer for light, where "RL" represents refracted light, "T" represents a tangent, "Norm" represents the perpendicular, and "IL" represents incident light. Fig. Figure 6 is a schematic representation of the propagation of incident light, where the refractive index n1 of a plurality of bonding units for light is greater than the refractive index n2 of an encapsulation layer for light. Fig. Figure 7 shows a representation of bubble formation. Fig. Figure 8 is a partially schematic representation of a large number of adhesive dots that completely enclose tapes. Fig.Figure 9 is a schematic cross-sectional representation of a large number of adhesive dots that partially enclose tapes. Fig. Figure 10 is a partially schematic representation of a large number of adhesive dots partially enclosing tapes. Fig. Figure 11 is a schematic cross-sectional representation of a photovoltaic module in comparative example 1.

[0033] The reference symbols are as follows: 100 represents a photovoltaic module; 110 represents a battery string; 111 represents a solar cell; 112 represents a conductive connector; 113 represents a bonding unit; 120 represents an encapsulation layer; 121 represents a front adhesive film; 122 represents a rear adhesive film; 131 represents a front protective substrate; 132 represents a rear protective substrate; 140 represents a busbar; 150 represents a frame; 160 represents a bubble; 161 represents a bubble inside an adhesive dot; and 162 represents a bubble outside an adhesive dot. DETAILED DESCRIPTION

[0034] To clarify and make more understandable the aforementioned objectives, features, and advantages of the present application, a detailed explanation of the specific implementation of the present application is given below. Unless specific conditions are indicated in the examples, the examples are carried out under conventional conditions or under conditions recommended by the manufacturer. Reagents or instruments for which no manufacturer is indicated are commercially available products.

[0035] In related technology, there is currently neither research on the use of adhesive properties to improve the performance of the photovoltaic module in the corresponding adhesive bonded photovoltaic module technology, nor a design requirement for an aesthetic appearance of the adhesive bonded photovoltaic module.

[0036] The related technique places greater emphasis on the stability of the multitude of bonding units, but does not address the problem that the presence of bonding units (such as an adhesive dot) can affect the aesthetics of the photovoltaic module, nor does it consider how the contour of the multitude of bonding units can be rendered invisible during visual inspection. According to the invention, the inventor adjusts the refractive index of the multitude of bonding units and the refractive index of an encapsulation layer to satisfy a specific relationship, while simultaneously adjusting the thickness of the encapsulation layer and the height of each of the multitude of bonding units to a specific ratio, so that the contour of the multitude of bonding units is not visible during visual inspection. At the same time, the inventor unexpectedly finds that this also improves the performance of the photovoltaic module.With reference to . Fig. 1 and Fig. 2 In some embodiments of the present application, a photovoltaic module 100 is provided. The photovoltaic module 100 comprises a battery string 110 and an encapsulation layer 120. The encapsulation layer 120 is attached to the battery string 110 to perform the function of encapsulating and protecting the battery string 110.

[0037] The battery string 110 comprises a plurality of solar cells 111 and a plurality of conductive connectors 112. The plurality of solar cells 111 are arranged in series, and two adjacent plurality of solar cells 111 are electrically connected to each other via the plurality of conductive connectors 112 to form the battery string 110. A plurality of bonding units 113 is provided between the encapsulation layer 120 and the battery string 110. The plurality of conductive connectors 112 are attached to the plurality of solar cells 111 by means of the plurality of bonding units 113 (such as a plurality of adhesive dots) to improve the connection stability of each of the plurality of conductive connectors 112.

[0038] In the present application, the refractive index of the plurality of bonding units 113 for light and the refractive index of the encapsulation layer 120 for light are adjusted such that the refractive index of the plurality of bonding units 113 for light and the refractive index of the encapsulation layer 120 for light satisfy a specific formula, thereby rendering the contour of the plurality of bonding units invisible upon visual inspection. Furthermore, the photovoltaic module produced according to the present application can further improve the performance of the photovoltaic module.

[0039] With reference to Fig. 3 and Fig.4. The compatibility between different refractive indices of various encapsulation materials has a relatively large influence on the performance and appearance of the photovoltaic module. In the embodiment of the present application, a material of the encapsulation layer and a material of each of the plurality of bonding units 113 are selected such that the refractive index of the encapsulation layer for light and the refractive index of the plurality of bonding units 113 for light meet a specific requirement, and after the photovoltaic module has been laminated, the plurality of bonding units 113 is hidden in the encapsulation layer 120, and the contour of the plurality of bonding units 113 is not visible from a surface of the encapsulation layer 120.In the embodiments of the present application, a characteristic value R is defined as the intensity of the light when the light from the encapsulation layer 120 enters the plurality of bonding units 113. A formula for the characteristic value R is as follows: R=|n2−n1|12(n1+n2); where a characteristic value Y is defined as a matching ratio between the height of the plurality of bonding units 113 and the thickness of the encapsulation layer 120. A formula for the characteristic value Y is defined as follows: Y=hH, where in the formula n1 represents the refractive index of the multitude of bonding units (113 for light) and n2 represents the refractive index of the encapsulation layer (120 for light). By adjusting a value for the refractive index n1 and a value for the refractive index n2, a characteristic value R lies in the range of 0.014 to 0.118, for example 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, 0.020, 0.030, 0.040, 0.050, 0.060, 0.070, 0.080, 0.090, 0.100, 0.110, 0.118, and so on.

[0040] H represents the thickness of the encapsulation layer 120. The thickness H of the encapsulation layer 120 is defined as the distance between a first position of the encapsulation layer, wherein the first position of the encapsulation is located on a surface of each of the plurality of solar cells and is predominantly oriented towards the surface of each of the plurality of solar cells along a perpendicular direction to the battery string, and a second position of the encapsulation layer, wherein the second position of the encapsulation is located on the surface of each of the plurality of solar cells and is predominantly oriented away from the surface of each of the plurality of solar cells along a perpendicular direction to the battery string, as shown in Fig.Figure 1 shows that when the encapsulation layer is arranged on two surfaces of each of the multiple solar cells, H represents the thickness of the encapsulation layer applied to one of the two surfaces of each of the multiple solar cells. A position for testing the thickness H can be selected at 5 mm near each of the multiple bonding units 113.

[0041] With reference to Fig.5 represents h, the height of each of the plurality of bonding units 113. The height h of each of the plurality of bonding units 113 is defined as the distance between a first position of each of the plurality of bonding units 113 and a second position of each of the plurality of bonding units 113 along the direction perpendicular to the plurality of solar cells 111. The first position of each of the plurality of bonding units 113 is located on a surface of each of the plurality of solar cells 111 and predominantly points towards the surface of each of the plurality of solar cells 111. The second position of each of the plurality of bonding units 113 is located on the surface of each of the plurality of solar cells 111 and predominantly points away from the surface of each of the plurality of solar cells 111.When the plurality of bonding units 113 is arranged on the two surfaces of each of the plurality of solar cells 111, h represents a distance of each of the plurality of bonding units 133 extending along a direction perpendicular to the battery string.

[0042] The characteristic value Y is less than or equal to 0.9 by adjusting the thickness H and the height h. The characteristic value Y can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and so on.

[0043] By adjusting the characteristic value R in a range of 0.014 to 0.118, the compatibility between the refractive index of the plurality of bonding units 113 for light, wherein the plurality of bonding units 113 is located on the surface of each of the plurality of solar cells, and the refractive index of the encapsulation layer 120 for light, wherein the encapsulation layer 120 is located on the surface of each of the plurality of solar cells, is optimized to achieve a refracted intensity of incident light (i.e.“IL”) between the plurality of bonding units 113 and the encapsulation layer 120 to reduce, while controlling the direction of propagation of the incident light in an intersection area between the encapsulation layer 120, the plurality of bonding units 113 and the plurality of conductive connectors 112, so that more incident light can reach a surface of each of the plurality of solar cells 111, thereby improving the performance of the photovoltaic module.Furthermore, the characteristic value Y is less than or equal to 0.9 by optimizing the compatibility between the height of each of the multiple bonding units 113 and the thickness of the encapsulation layer 120 on the surface of each of the multiple solar cells 111, thus preventing bubble formation between the multiple bonding units 113 and the encapsulation layer 120, or within the multiple bonding units 113 or the encapsulation layer 120, which leads to a further improvement in the utilization rate of the incident light. Since reflected light (i.e., "RL") is greatly reduced, there is no clear boundary between the multiple adhesive dots and an adhesive film, resulting in visual integration and improving the aesthetic performance of the photovoltaic module.

[0044] If the coefficient of friction R is less than 0.014, n1 is close to n2. When the incident light from the encapsulation layer 120 enters the multitude of bonding units 113 (as the multitude of bonding units), the incident light propagates almost in a straight line and is slightly blocked by the bands, which does not contribute to increasing the performance of the photovoltaic module. If the coefficient of friction R is greater than 0.118, the outline of the multitude of adhesive dots may be visible on the surface of the photovoltaic module, so the appearance and performance of the photovoltaic module are not optimal.

[0045] If the characteristic value Y is greater than 0.9, i.e., the thickness H is too small or the height h is too large, and if the thickness H of the encapsulation layer 120 is too small, a bubble will easily form in the adhesive film due to insufficient filling of the adhesive film, the insufficient filling being due to an insufficient amount of adhesive film, thus impairing the performance and appearance of the photovoltaic module. If a bubble occurs on the surface of any of the multiple adhesive dots, since the refractive index of the bubble is close to 1, the intensity R of the reflected light at the interface between the bubble and the multiple adhesive dots will be significantly greater than 0.118, so that part of the adhesive dot may be visible on the surface of the photovoltaic module. If any of the multiple bonding units 113 (like the multiple adhesive dots) is too large, with respect to Fig.7. Due to a specific property of the printing process, the multitude of adhesive dots are prone to carrying a bubble, and the bubble penetrates the multitude of adhesive dots, leading to the formation of a bubble 160 (including a bubble 161 inside an adhesive dot and a bubble 162 outside an adhesive dot). Furthermore, if each of the multitude of bonding units 113 is too large, a narrow gap between the tape and the multitude of adhesive dots is difficult to fill, and a bubble may also occur, making the multitude of adhesive dots visible, which is detrimental to the performance of the photovoltaic module.

[0046] In some embodiments, the characteristic value R lies within a range of 0.02 to 0.097 by adjusting the values ​​of the refractive index n1 and the refractive index n2. By controlling the characteristic value R within this range, battery efficiency can be further improved, while the numerous adhesive dots on the surface of the photovoltaic module remain invisible.

[0047] In some embodiments, to better optimize the compatibility between the adhesive film and the adhesive and to improve the utilization rate of an incident light source, the refractive index n1 of the plurality of bonding units 113 for light is smaller than the refractive index n2 of the encapsulation layer 120 for light. When the refractive index n1 is smaller than the refractive index n2, the encapsulation layer 120 is considered an optically denser medium, each of the plurality of bonding units 113 is considered an optically less dense medium, and when the light enters the optically less dense medium from the optically denser medium, the refracted light moves away from the perpendicular (i.e., norm), as shown in Fig. Figure 5 shows that under this condition, more incident light can reach the surface of the multitude of solar cells, which promotes the increase in the performance of the photovoltaic module.

[0048] In contrast, in Fig.Figure 6 shows a schematic representation of light propagation when the refractive index n1 is greater than the refractive index n2, and the incident light approaches the vertical (i.e. the “normal”), which tends to block the bands and does not help to improve the performance of the photovoltaic module.

[0049] In some embodiments, the refractive index n1 of the plurality of bonding units 113 for light is in a range of 1.35 to 1.6, for example 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, and so on. The refractive index of an adhesive designed to form the plurality of bonding units 113 for light is essentially equal to the refractive index n1 of the plurality of bonding units 113. The refractive index of the adhesive designed to form the plurality of bonding units 113 is also in a range of 1.35 to 1.60. The adhesive designed to form the plurality of bonding units 113 is selected from the group consisting of an organic silicone adhesive, an acrylic adhesive, an epoxy resin adhesive, and any combination thereof.

[0050] Furthermore, the refractive index n2 of the encapsulation layer 120 for light is in the range of 1.40 to 1.65, for example 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, and so on. The encapsulation layer 120 is formed by laminating and crosslinking an encapsulation adhesive film, and the encapsulation adhesive film is selected from the group consisting of an encapsulation adhesive film made of polyolefin elastomer, an encapsulation adhesive film made of ethylene vinyl acetate copolymer, an encapsulation adhesive film of a coextruded product with polyolefin elastomer and ethylene vinyl acetate copolymer, and any combination thereof.

[0051] If the refractive index n1 of the plurality of bonding units 113 is too low or too high (less than 1.35 or greater than 1.65), larger quantities of substances with low or high refractive index are required for modification of the plurality of bonding units 113, which significantly affects other properties of the adhesive.

[0052] In some embodiments, the height of each of the plurality of bonding units is in a range of 50 µm to 280 µm, for example 50 µm, 80 µm, 100 µm, 130 µm, 150 µm, 180 µm, 200 µm, 230 µm, 250 µm, 280 µm, and so on. The thickness H of the encapsulation layer can be in a range of 300 µm to 400 µm, for example 300 µm, 330 µm, 350 µm, 380 µm, 400 µm, and so on.

[0053] In the embodiments of the present application, the refractive index n1 of the plurality of bonding units 113 for light and the refractive index n2 of the encapsulation layer 120 for light are adjusted such that a specific relationship is satisfied, and a ratio Y of the height h of each of the plurality of bonding units 113 to the thickness H of the encapsulation layer 120 is controlled such that specific values ​​are met, so that the plurality of adhesive dots on the surface of the photovoltaic module cannot be detected. In practical implementation, the following method can be used to determine whether the plurality of adhesive dots is detectable.

[0054] The gray values ​​of different areas of the photovoltaic module are recorded using a camera by capturing the surface of the photovoltaic module, so that a characteristic value G can be calculated using the following formula: G=|g2−g1|, where the characteristic value G represents a gray value threshold, g1 represents a gray value of a portion of the surface of the photovoltaic module 100 without the plurality of bonding units 113 (such as a portion of the surface of the plurality of solar cells 100 mm near the plurality of bonding units 113), and g2 represents a gray value of another portion of the surface of the photovoltaic module with the plurality of bonding units. If the characteristic value G is greater than 20, the plurality of adhesive dots can be detected. If the characteristic value G is less than or equal to 20, the plurality of adhesive dots cannot be detected. In the embodiments of the present application, the photovoltaic module is tested by the above method, and the characteristic value G is less than or equal to 20.

[0055] In some embodiments, the plurality of conductive connectors can consist of 112 strips. The material of the strips is not limited and can be copper wire. The copper wire can be coated on its surface with a lead-containing solder. The copper wire can be commercially available.

[0056] In some embodiments, the plurality of bonding units 113 can consist of at least the plurality of adhesive dots, the plurality of adhesive sections, or a combination of both, formed by curing the adhesive. The adhesive can be cured by lamp heating, UV irradiation, or infrared heating. The type of each of the plurality of adhesives is not limited. One position of each of the plurality of adhesive dots corresponds to one position of each of the strips. The strips are attached to the plurality of solar cells 111 by means of the spaced-apart plurality of adhesive dots.

[0057] With reference to Fig. 1, Fig. 2 and Fig.4. The plurality of solar cells 111 are arranged at intervals from one another. A surface of one of the plurality of solar cells 111 is connected to a opposite surface of an adjacent plurality of solar cells 111, so that the plurality of solar cells 111 are connected in series. The plurality of bonding units 113 are arranged on the two surfaces of the battery string 110. One end of each of the plurality of conductive connectors 112 extends from one end of the plurality of solar cells 111 to another corresponding end of the plurality of solar cells 111 along an arrangement direction of the plurality of solar cells 111. The plurality of conductive connectors 112 are arranged at intervals along a direction perpendicular to the arrangement direction of the plurality of solar cells.

[0058] In some types of solar cell arrays, such as back-contact (BC) batteries, the multitude of conductive connectors is arranged only on one surface of the battery string 110. Similarly, the multitude of bonding units 113 is arranged only on one surface of the battery string 110.

[0059] In some embodiments, with reference to Fig.1. On the front and rear of each of the plurality of solar cells 111, both the plurality of conductive connectors 112 and the plurality of bonding units 113 are provided. The encapsulation layer 120 comprises a front adhesive film 121 and a rear adhesive film 122. The front adhesive film 121 is attached to a front of the battery string 110, and the rear adhesive film 122 is attached to a rear of the battery string 110. When the plurality of conductive connectors 112 and the plurality of bonding units 113 are arranged on both the front and rear of each of the plurality of solar cells 111, the front of the battery string 110 is encapsulated by the front adhesive film 121, and the rear of the battery string 110 is encapsulated by the rear adhesive film 122.

[0060] If the plurality of conductive connectors 112 and the plurality of bonding units 113 are arranged both on the front of each of the plurality of solar cells 111 and on the back of each of the plurality of solar cells 111, and the encapsulation layer 120 comprises the front adhesive film 121 and the back adhesive film 122, the photovoltaic module satisfies at least one of the following conditions: that the characteristic value R is in a range of 0.014 to 0.118, such that the plurality of adhesive points arranged on the front of the photovoltaic module are hidden in the adhesive film.

[0061] In some embodiments, the photovoltaic module 100 further comprises a front protective substrate 131 and a rear protective substrate 132. The front protective substrate 131 is attached to an end face of the front adhesive film 121 facing away from the battery string 110, and the rear protective substrate 132 is attached to an end face of the rear adhesive film 122 facing away from the battery string 110. The front protective substrate 131 and the rear protective substrate 132 can be transparent substrates to protect the front and rear sides of the photovoltaic module, respectively.

[0062] The front protective substrate 131 can be made of glass to improve light transmission.

[0063] The rear protective substrate 132 can consist of at least one of the materials glass and polymer materials. If the rear protective substrate 132 consists of polymer materials, the rear protective substrate is made of at least one of glass and one of polymer materials. The polymer material includes polyethylene terephthalate, polyolefin copolymer, polyamide, polyvinyl fluoride, polyvinylidene fluoride, and any combination thereof.

[0064] In some embodiments, the photovoltaic module 100 further comprises a frame 150 and a busbar 140. The frame 150 provides protection for the edge area of ​​the photovoltaic module 100, and two adjacent battery strings 110 are connected to each other via the busbar 140 to form a ring-shaped unit.

[0065] To adapt and optimize different manufacturing processes and application scenarios of the photovoltaic module, the tapes can be completely encased by the numerous adhesive dots (in Fig. 1 and Fig. 8 shown) or partially encased by the multitude of adhesive dots (in Fig. 9 and Fig. 10 shown).

[0066] With reference to Fig. 1 and Fig.8, at a position where the plurality of bonding units 113 is located, surfaces of the plurality of conductive connectors 112 are encased by the plurality of bonding units 113, and the surfaces of the plurality of conductive connectors 112 are completely encased by the plurality of bonding units 113. When the battery string 110 is manufactured by applying an adhesive for fixation and subsequent welding, the surfaces of the plurality of conductive connectors 112 are completely encased by the plurality of adhesive dots, as shown in Fig. 8 shown.

[0067] In other embodiments, with reference to Fig. 9 and Fig.10, at a position where the plurality of bonding units 113 is located, each of the plurality of bonding units 113 is arranged between each of the plurality of conductive connectors 112 and each of the plurality of solar cells 111. Part of the surface of the plurality of conductive connectors 112 is covered by the plurality of bonding units 113, and another part of the surface of the plurality of conductive connectors 112, facing away from the plurality of solar cells 111, is not covered by the plurality of bonding units 113. If the plurality of conductive connectors 112 is fixed by applying the adhesive for fixation and subsequent welding, or solely by applying the adhesive, the plurality of conductive connectors 112 is partially covered by the plurality of adhesive dots, as shown in Fig. 10 shown.

[0068] The present application provides a manufacturing process for a photovoltaic module. The process comprises arranging a plurality of conductive connectors 112 on at least one surface of each of a plurality of solar cells 111 along a thickness direction of each of the plurality of solar cells 111, connecting the plurality of conductive connectors 112 to the plurality of solar cells 111 by means of a plurality of bonding units 113 to form a battery string 110, and encapsulating the battery string 110 by means of an encapsulation layer 120 of the photovoltaic module.

[0069] During the manufacturing process of the photovoltaic module, the refractive index of the encapsulation layer 120 for light, the refractive index of the adhesive for light, and the thickness of the encapsulation layer 120 are matched. The characteristic value R is defined as the intensity of the refracted light when the light from the encapsulation layer 120 enters the multitude of bonding units 113, and the characteristic value R satisfies the following formula (1): R=|n2−n1|12(n1+n2). The characteristic value Y is designed to represent a matching ratio between the thickness of the encapsulation layer 120 and the height of each of the plurality of bonding units 113, and the characteristic value Y satisfies the following formula (2): Y=hH, n1 represents a refractive index of the multitude of bonding units for light, n2 represents the refractive index of the encapsulation layer for light, The characteristic value R lies in a range of 0.014 to 0.118, by adjusting the refractive index n1 of the multitude of bonding units for light and the refractive index n2 of the encapsulation layer for light; The characteristic value Y is less than or equal to 0.9; H represents the thickness of the encapsulation layer 120. The thickness H of the encapsulation layer 120 is defined as the distance between a first position of the encapsulation layer and a second position of the encapsulation layer along a direction perpendicular to the battery string. The first position of the encapsulation is located on the surface of each of the plurality of solar cells and predominantly facing the surface of each of the plurality of solar cells along a direction perpendicular to the battery string. The second position of the encapsulation is located on the surface of each of the plurality of solar cells and predominantly facing away from the surface of each of the plurality of solar cells. h represents the height of each of the plurality of bonding units 113. The height h of each of the plurality of bonding units 113 is defined as a distance between a first position of each of the plurality of bonding units 113, wherein the first position of each of the plurality of bonding units 113 is located on a surface of each of the plurality of solar cells 111 and predominantly in the direction of the surface of each of the plurality of solar cells 111, and a second position of each of the plurality of bonding units 113, wherein the second position of each of the plurality of bonding units 113 is located on the surface of each of the plurality of solar cells 111 and predominantly facing away from the surface of each of the plurality of solar cells 111 along the direction perpendicular to the plurality of solar cells 111.

[0070] During a manufacturing process, the refractive index n1 of the encapsulation layer 120 for light and the refractive index n2 of the multitude of bonding units 113 for light are adjusted, and the encapsulation layer 120 can be better matched with the multitude of bonding units 113 so that the contour of the multitude of adhesive points is not visible from the surface of the photovoltaic module, thus facilitating the increase in the performance of the photovoltaic module.

[0071] In some embodiments, the plurality of solar cells 111 is arranged along a first direction. A fine grid line of each of the plurality of solar cells 111 is arranged along a second direction. The first direction intersects the second direction. The plurality of conductive connectors 112 is arranged along the first direction when the plurality of conductive connectors 112 is assembled. The manufacturing process of the battery string 110 can employ welding and dispensing techniques. The battery string 110 can be manufactured by dispensing adhesive for fixation and subsequent welding, or by welding and subsequent dispensing of adhesive for fixation.

[0072] In the embodiments of the present application, a photovoltaic power generation device is provided. The photovoltaic power generation device comprises one photovoltaic module 100 in the embodiments of the present application. The number of photovoltaic modules 100 can be M, with M photovoltaic modules connected in series, where M is an integer that is at least 1. The number of photovoltaic modules can be adjusted as required.

[0073] In some embodiments, the photovoltaic power generation device may include an inverter. An output of the photovoltaic power generation device is connected to an input of the inverter, which is designed for photovoltaic power generation.

[0074] The features and performance of the present application are explained in more detail below using the following examples. First example

[0075] A manufacturing process for a photovoltaic module is provided in this example. The process comprises the following steps. (1) Production of the materials

[0076] An adhesive was prepared. Specifically, a commercially available organic silicone adhesive (from Delangju New Materials Co., Ltd., model SE-6002) was obtained. The organic silicone adhesive was cured, and its refractive index for light was 1.42 at a temperature range of 24°C to 26°C.

[0077] An encapsulation adhesive film (including a front encapsulation adhesive film and a rear encapsulation adhesive film) is prepared. Specifically, a front encapsulation adhesive film was commercially sourced as EPE (expandable polyethylene) encapsulation adhesive film (from Hangzhou Foster Applied Materials Co., Ltd., model EP304), and a rear encapsulation adhesive film was commercially sourced as EVA (ethylene-vinyl acetate copolymer) encapsulation adhesive film (from Hangzhou Foster Applied Materials Co., Ltd., model F406P). After lamination of the front and rear encapsulation adhesive films, the refractive index n2 of the front encapsulation adhesive film and the refractive index n2 of the rear encapsulation adhesive film were both 1.48 at a temperature in the range of 24°C to 26°C.

[0078] A strip is prepared. Specifically, a copper wire with tin-coated, lead-containing solder was obtained commercially, the thickness of the solder layer on the copper wire being 15 µm and the diameter of the copper wire being 0.22 mm.

[0079] A solar cell was selected as a main gate-less solar cell made of crystalline silicon (manufactured by Tongwei Solar Energy (Meishan) Co., Ltd., model SY11), with the size of the solar cell being 210 mm × 210 mm, the thickness of the solar cell being 130 µm, and the diameter of one half of the solar cell being 210 mm × 105 mm.

[0080] A flux was acquired from Shaoxing Tuobang New Energy Co., Ltd., and the flux model was FC10V16-6.

[0081] A busbar was a flat, reflective busbar available commercially, made from tin-plated copper strip.

[0082] A front glass (i.e., front protective substrate 131) was commercially available double-coated glass.

[0083] A back glass (i.e., rear protective substrate 132) was unglazed, commercially available transparent three-hole glass, with a back glass diameter of 12 mm. (2) Manufacture of a battery string

[0084] The front and back surfaces of eleven and a half solar cells were sequentially printed with a suitable amount of adhesive. The distance between adjacent printed adhesive areas was 10 mm. The tape was dipped for 1 second into a flux solution and then placed onto the adhesive surface. One orientation of the tape was parallel to the shorter side of the half solar cell. A positive electrode of one solar cell was sequentially connected to a negative electrode of an adjacent solar cell via the tape. The tape was bonded to eleven and a half solar cells under a welding machine's light box while the adhesive cured. (3) Encapsulation

[0085] The front glass, the front encapsulation adhesive film, the battery string, the rear adhesive film, and the back glass were stacked sequentially. Adjacent battery strings were connected via the busbars, and then the front and rear encapsulation adhesive films were melted and cross-linked by lamination to create an encapsulated battery string. The encapsulated battery string is cut to size and fitted with a frame to form a photovoltaic module.

[0086] A partially schematic representation of the photovoltaic module produced in the first example was shown in Fig. Figure 4 shows that the outline of numerous adhesive dots on the photovoltaic module was not visible upon visual inspection. Examples two to six and eleven

[0087] The second to sixth examples and the eleventh example were essentially the same as the first example, except that the refractive index n1 of an adhesive for light and the refractive index n2 for light differed, as shown in Table 1. Seventh to tenth example

[0088] Examples seven to ten were essentially the same as example three, except that the thickness H of an adhesive film after lamination and the height of an adhesive after curing differed, as shown in Table 1. First to sixth comparative example

[0089] The first to sixth comparison examples were essentially the same as the first example, except that the refractive index n1 of an adhesive for light, a refractive index n2, a thickness H of an adhesive film after lamination, and a thickness h of an adhesive after curing differed, as shown in Table 1.

[0090] A partially schematic representation of the photovoltaic module produced by the first to sixth comparison examples was shown in Fig. 11 is shown, with the large number of adhesive dots clearly visible. First test example

[0091] The photovoltaic modules obtained from the first to tenth example and the first to sixth comparison example, as well as the test result, are shown in Table 1.

[0092] A testing procedure includes the following tests. (1) An adhesive spot test comprised a detection method for the contour of the multitude of adhesive spots after the lamination of the photovoltaic module. A surface of the photovoltaic module was imaged with a camera, and gray values ​​of different areas of the surface of the photovoltaic module were determined using a defined algorithm program or software such as R3 and Lµmi Tools. The gray value of the different areas of the surface of the photovoltaic module satisfies the following formula: G = |g2 - g1|.

[0093] A characteristic value G represents a threshold value for the gray value. g1 represents the gray value of a portion of the photovoltaic module's surface without the numerous adhesive dots, and g2 represents the gray value of another portion of the photovoltaic module's surface with the numerous adhesive dots. If the characteristic value G was greater than 20, the numerous adhesive dots could be detected. If the characteristic value G was less than or equal to 20, the numerous adhesive dots could not be detected.

[0094] (2) A refractive index test comprised curing and laminating the commercially sourced adhesive and the commercially sourced adhesive film at a process temperature and then cooling them to room temperature (in a range of 24°C to 26°C) to obtain a sample for testing. The refractive index of the sample to be tested was measured using a refractive index testing device (such as an Abbe refractometer) in an environment in the range of 24°C to 26°C.

[0095] (3) Performance measurement of the photovoltaic module included testing the performance of the photovoltaic module according to the IEC 61215 standard. Table 1: Test results for the performance of a photovoltaic module, obtained through examples and comparison examples. Number of examples Refractive index n1 of the cured adhesive Refractive index n1 of the laminated adhesive film Characteristic value R Thickness H of delaminated adhesive film / µm Height of cured adhesive / µm Key value Y Result of the visual inspection Characteristic value G Result of the adhesive point Performance First example 1,46 1,48 0,014 360 150 0,42 The glue point was not visible ≤20 The glue point was not detectable 6152W Second example 1,45 1,48 0,020 360 150 0,42 The glue point was not visible ≤20 The glue point was not detectable 615,4W Third example 1,42 1,48 0,041 360 150 0,42 The glue point was not visible ≤20 The glue point was not detectable 615,7W Fourth example 1,37 1,51 0,097 360 150 0,42 The adhesive dot was not ≤20 The adhesive dot was not 615,3W visible recognizable Fifth example 1,40 1,55 0,102 360 150 0,42 The glue point was not visible ≤20 The glue point was not detectable 615,1W Sixth example 1,36 1,53 0,118 360 150 0,42 The glue point was not visible ≤20 The glue point was not detectable 615,0W Seventh example 1,42 1,48 0,041 300 270 0,9 The glue point was not visible ≤20 The glue point was not detectable 615,5W Eighth example 1,42 1,48 0,041 350 200 0,57 The glue point was not visible ≤20 The glue point was not detectable 615,5 Ninth example 1,42 1,48 0,041 400 50 0,13 The adhesive ≤20 The adhesive 615,4 kt was not visible kt was unrecognizable W Tenth example 1,42 1,48 0,041 400 280 0,7 The glue point was not visible ≤20 The glue point was not detectable 615,5W Eleventh example 1,48 1,42 0,041 360 150 0,42 The glue point was not visible ≤20 The glue point was not detectable 615,0W First comparison example 1,47 1,48 0,007 360 150 0,42 The glue point was not visible ≤20 The glue point was not detectable 614,8W Second comparative example 1,38 1,57 0,129 360 150 0,42 Part of the adhesive dot was visible >20 The adhesive dot was recognizable. 614,8W Third comparative example 1,35 1,65 0,200 360 150 0,42 The dot of adhesive was visible >20 The adhesive dot was recognizable. 614,7W Fourth comparative example 1,42 1,48 0,041 300 280 0,93 Part of the adhesive dot was visible >20 The glue point was not detectable 614,7W

[0096] It follows that if the characteristic value R and the characteristic value Y were outside a range defined by the present application (i.e., the characteristic value R is not in a range of 0.014 to 0.118, the characteristic value Y is not less than or equal to 0.9), the performance of the photovoltaic module was reduced accordingly, and the adhesive spot on the surface of the photovoltaic module could not be detected, which was not conducive to improving the aesthetics of the photovoltaic module.

[0097] Comparing the first example with the sixth, the performance increased with increasing characteristic value R and then decreased again. In the second through fourth examples, the characteristic value R ranged from 0.02 to 0.097.

[0098] Comparing the third example with examples seven through ten, the following applies: If the thickness H, the height h, and the characteristic value Y were all within the same range (i.e., the characteristic value Y was not less than or equal to 0.9), the characteristic value Y significantly influenced the performance of the photovoltaic module, and the numerous adhesive dots were not visible upon visual inspection. Comparing example 3 and example 11, the characteristic value R and the characteristic value Y were the same, but in example 11, the refractive index n1 was greater than the refractive index n2, and an optical transmission path approached the solder strip (see Fig.6), which resulted in shading and reduced the performance of the photovoltaic module. In the twelfth example, the characteristic value Y was within a range, but the height h of each of the multiple adhesive dots was too large, causing air to enter the adhesive during printing. This resulted in the laminated adhesive dots having an internal bubble. The intensity of reflected light at an interface between the bubble and the multiple adhesive dots was relatively high, making the multiple adhesive dots visible upon visual inspection.

[0099] In the first comparison example, the refractive index n1 was close to the refractive index n2, resulting in a value R that was too low, causing the light to be blocked by the band. In the second comparison example, the difference between the refractive index n1 and the refractive index n2 was too large, resulting in a relatively high value. In both the first and second comparison examples, the power output of the photovoltaic modules was relatively low. Furthermore, in the second comparison example, the numerous adhesive dots were visible because the value R was too high. In the third comparison example, the value R was relatively high, making the numerous adhesive dots visible.In the fourth example, the characteristic value Y was relatively large, the height h of each of the multitude of adhesive dots was relatively large, and the thickness of the adhesive film was too small, resulting in insufficient filling of the adhesive film, so that a bubble appeared on the surface of the multitude of adhesive dots, which increased the reflection intensity of the light on the surface of the multitude of adhesive dots, making the multitude of adhesive dots visible.

[0100] The foregoing statements are merely some examples of the present application and do not constitute a limitation of the present application. For those skilled in the art, the present invention may have various modifications and variations. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] CH 202411784867.0

[0001]

Claims

[1] Photovoltaic module, comprising: a battery string, wherein the battery string comprises a plurality of solar cells and a plurality of conductive connectors, wherein two adjacent solar cells are electrically connected to each other via the plurality of conductive connectors; and an encapsulation layer, wherein the encapsulation layer is attached to the battery string; wherein a plurality of bonding units are provided between the encapsulation layer and the battery string, the plurality of bonding units being designed to connect the plurality of conductive connectors on the plurality of solar cells; a characteristic value R satisfies the following formula (1): R=|n2−n1|12(n1+n2); a characteristic value Y satisfies the following formula (2): Y=hH, where the characteristic value R lies in a range from 0.014 to 0.118; n1 represents a refractive index of the multitude of bonding units for light; n2 represents the refractive index of the encapsulation layer for light; the characteristic value Y is less than or equal to 0.9; H represents the thickness of the encapsulation layer; h represents the height of each of the multiple bonding units; and The height of each of the multiple bonding units is in a range of 50 µm to 280 µm. [2] Photovoltaic module according to claim 1, wherein the characteristic value R is in a range of 0.020 to 0.

097. [3] Photovoltaic module according to claim 1 or 2, wherein the refractive index n1 of the plurality of bonding units for light is smaller than the refractive index n2 of the encapsulation layer for light. [4] Photovoltaic module according to claim 1 or 2, wherein the plurality of bonding units is arranged on at least one surface of the battery string; and / or the plurality of bonding units is formed by curing an adhesive. [5] Photovoltaic module according to claim 4, wherein the refractive index n1 of the plurality of bonding units for light is in a range of 1.35 to 1.60; and / or wherein the adhesive formed to form the plurality of bonding units is selected from the group consisting of an organic silicone adhesive, an acrylic adhesive, an epoxy resin adhesive and any combination thereof. [6] Photovoltaic module according to claim 3, wherein the refractive index n2 of the encapsulation layer for light is in a range of 1.40 to 1.65 and the thickness of the encapsulation layer is in a range of 300 µm to 400 µm; and / or wherein the encapsulation layer is formed by laminating and crosslinking an encapsulation adhesive film and the encapsulation adhesive film is selected from the group consisting of an encapsulation adhesive film made of polyolefin elastomer, an encapsulation adhesive film made of ethylene vinyl acetate copolymer, an encapsulation adhesive film of a coextrusion product with polyolefin elastomer and ethylene vinyl acetate copolymer and any combination thereof. [7] Photovoltaic module according to claim 1, wherein grey values ​​of different areas of the photovoltaic module are obtained with a camera by capturing a surface of the photovoltaic module in order to calculate a characteristic value G; where the characteristic value G satisfies the following formula: G = |g2 - g1|; where the characteristic value G represents a threshold value of the gray value, g1 represents a gray value of a part of the surface of the photovoltaic module without the plurality of bonding units, and g2 represents a gray value of another part of the surface of the photovoltaic module with the plurality of bonding units; and where the characteristic value G is less than or equal to 20. [8] Photovoltaic module according to claim 1, wherein a surface of each of the plurality of conductive connectors at a position where the plurality of bonding units is located is enclosed by each of the plurality of bonding units. [9] Photovoltaic module according to claim 1, wherein at a position where the plurality of bonding units is located, each of the plurality of bonding units is arranged between each of the plurality of conductive connectors and each of the plurality of solar cells, and a part of a surface of each of the plurality of conductive connectors is covered by each of the plurality of bonding units. [10] Photovoltaic module according to claim 1, wherein a front surface of each of the plurality of solar cells and a rear surface of each of the plurality of solar cells are provided with both the plurality of conductive connectors and the plurality of bonding units, the encapsulation layer comprises a front adhesive film and a rear adhesive film, the front adhesive film is attached to a front surface of the battery string and the rear adhesive film is attached to a rear surface of the battery string; the photovoltaic module meets at least one of the following conditions: The characteristic value R lies in a range of 0.014 to 0.118; a ratio Y of the height of each of the multiple bonding units to the thickness of the front adhesive film is less than or equal to 0.9; and / or the multitude of conductive connectors are tapes. [11] Photovoltaic module according to claim 10, wherein the plurality of solar cells are arranged at a distance from each other and a surface of one of the plurality of solar cells is connected to an opposite surface of an adjacent plurality of solar cells. [12] Photovoltaic module according to claim 10, further comprising a front protective substrate and a rear protective substrate, wherein the front protective substrate is attached to an end face of the front adhesive film facing away from the battery string and the rear protective substrate is attached to an end face of the rear adhesive film facing away from the battery string. [13] Photovoltaic module according to claim 12, wherein the front protective substrate consists of glass; and / or the rear protective substrate consists of at least one of the materials glass and high molecular weight polymer, wherein the high molecular weight polymer comprises polyethylene terephthalate, polyolefin copolymer, polyamide, polyvinyl fluoride and polyvinylidene fluoride. [14] Photovoltaic power generation device comprising the photovoltaic module according to any one of claims 1 to 13; wherein the number of photovoltaic modules is M, M photovoltaic modules are connected in series and M is an integer that is at least 1.

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