Photovoltaic module and preparation method thereof, and photovoltaic power generation device

Abstract

The present invention discloses a photovoltaic module and a preparation method thereof and a photovoltaic power generation device, and relates to the field of photovoltaic technology. The present invention regulates the refractive index of the bonding unit and the encapsulation layer to light, and the characteristic value R is 0.014-0.118, so that the incident light is rarely reflected between the bonding unit and the adhesive film interface, and by controlling the ratio of the height of the bonding unit to the thickness of the encapsulation layer Y≤0.9, no bubbles are formed between the bonding unit and the encapsulation layer and in the body structure, thereby improving the utilization rate of the component to the incident light, which is beneficial to improving the power of the component; the outline of the bonding unit cannot be seen in the laminated component under visual inspection, so that it is hidden in the encapsulation layer, and the aesthetic appearance of the component is enhanced.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a photovoltaic module and a preparation method thereof, and a photovoltaic power generation device. Background Art

[0002] The metal electrodes on the front and back of the cell are used to conduct internal current and can be divided into the main grid (Busbar) and the secondary grid (also known as the fine grid, Finger). The main grid mainly collects the current of the secondary grid and connects in series, while the secondary grid is used to collect photogenerated carriers. The grid line pattern has developed from the past 4BB and 5BB to MBB (Multiple-Busbar, 9-15 grids), and then to the SMBB technology (Super-Multiple Busbar, 16 grids and above) which has been popular in recent years. The glue interconnection component technology is a further upgrade of the SMBB technology and has gradually become one of the mainstream trends in current research and development.

[0003] Glue has attracted much attention as one of the key materials used in glue interconnect component technology. Commonly used glues are mainly divided into organic silicone water system, acrylic glue system and epoxy resin glue system. The properties of the glue itself, such as bonding strength, yellowing performance, hardness, etc., all have a great impact on the performance of the component, and are also factors that usually need to be considered in the research and development of existing technologies. In the actual research and development and trial production process, the printing quality of the glue, the number of glue points, the size of the glue points, etc. also affect the reliability of component production. For example, deformation of the glue points, reduction in the number and size of the glue points, can easily lead to insufficient bonding strength of the glue, thereby affecting the yield of the component. There is currently no relevant research in the existing glue interconnect component technology that uses the characteristics of the glue itself to improve the power generation of the component, nor is there a design requirement for the appearance of the glue interconnect component.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The object of the present invention is to provide a photovoltaic module and a preparation method thereof and a photovoltaic power generation device, aiming to improve the power generation capacity of the module on the basis of ensuring the module yield, and at the same time improve the appearance of the module.

[0006] The present invention is achieved in that:

[0007] In a first aspect, the present invention provides a photovoltaic module, comprising:

[0008] A battery string, the battery string includes a plurality of solar cells and a plurality of conductive connectors, and adjacent solar cells are conductively connected through the conductive connectors;

[0009] An encapsulation layer, the encapsulation layer is attached to the surface of the battery string;

[0010] A bonding unit is also provided between the encapsulation layer and the surface of the battery string, and the bonding unit bonds the conductive connector to the surface of the solar cell sheet;

[0011] The expression for defining the eigenvalue R is formula (1):

[0012] The expression for defining the eigenvalue Y is formula (2):

[0013] Formula (1);

[0014] Formula (2);

[0015] The value of R is 0.014-0.118;

[0016] n1 represents the refractive index of the bonding unit to light;

[0017] n2 represents the refractive index of the packaging layer to light.

[0018] The value of Y satisfies Y≤0.9;

[0019] H represents the thickness of the encapsulation layer;

[0020] h represents the height of the bonding unit.

[0021] In an optional embodiment, the value of R is 0.020-0.097.

[0022] In an optional embodiment, the refractive index n1 of the bonding unit to the light and the refractive index n2 of the encapsulation layer to the light satisfy: n1 <n2。

[0023] In an optional embodiment, the bonding unit is provided on only one side of the surface of the battery string or on both sides of the surface of the battery string;

[0024] And / or, the bonding unit is formed by curing glue.

[0025] In an optional embodiment, the refractive index n1 of the bonding unit to light is 1.35-1.60; the height of the bonding unit is 50-280 μm;

[0026] And / or, the glue used to form the bonding unit is selected from at least one of organic silicone glue, acrylic glue and epoxy resin glue.

[0027] In an optional embodiment, the refractive index n2 of the encapsulation layer to light is 1.40-1.65; the thickness of the encapsulation layer is 300-400 μm;

[0028] And / or, the encapsulation layer is formed by laminating and cross-linking the encapsulation film, and the encapsulation film is selected from at least one of a POE encapsulation film, an EVA encapsulation film and an EPE encapsulation film.

[0029] In an optional implementation, a camera is used to photograph the component surface, and then grayscale values ​​of different regions are obtained to calculate the eigenvalue G:

[0030] G = |g2-g1|;

[0031] Among them, the characteristic value G is the gray value threshold, g1 is the gray value of the area without bonding unit on the surface of the photovoltaic module, and g2 is the gray value of the area with bonding unit on the surface of the photovoltaic module;

[0032] The value of G satisfies: G≤20.

[0033] In an optional embodiment, at the location of the bonding unit, the bonding unit covers the surface of the conductive connecting member.

[0034] In an optional embodiment, at the location of the bonding unit, the bonding unit is located between the conductive connector and the solar cell sheet, and the bonding unit covers a portion of the surface of the conductive connector.

[0035] In an optional embodiment, the front and back sides of the solar cell sheet are both provided with conductive connectors and bonding units, the encapsulation layer includes a front adhesive film and a back adhesive film, the front adhesive film is attached to the front side of the cell string, and the back adhesive film is attached to the back side of the cell string;

[0036] At least the following requirements are met: the characteristic value R is 0.014-0.118; the ratio of the bonding unit height to the front film thickness Y is ≤ 0.9;

[0037] And / or, the conductive connecting member is a welding strip.

[0038] In an optional embodiment, a plurality of solar cell sheets are arranged at intervals, and one side of a solar cell sheet is connected to the reverse side of another adjacent solar cell sheet through a conductive connector.

[0039] In an optional embodiment, it also includes a front protective substrate and a back protective substrate, the front protective substrate is bonded to the end face of the front adhesive film away from the battery string, and the back protective substrate is bonded to the end face of the back adhesive film away from the battery string.

[0040] In an optional embodiment, the material of the front protection substrate is glass;

[0041] And / or, the material of the back protection substrate is selected from at least one of glass and high molecular polymer materials, wherein the high molecular polymer material includes polyethylene terephthalate, polyolefin copolymer, polyamide, polyvinyl fluoride and polyvinylidene fluoride.

[0042] In a second aspect, the present invention provides a method for preparing a photovoltaic module according to any one of the aforementioned embodiments, comprising: arranging a conductive connector on at least one side surface of a plurality of solar cells in a thickness direction, and bonding the conductive connector to the solar cells by a bonding unit to form a cell string; and encapsulating the cell string by an encapsulation layer;

[0043] The expression for defining the eigenvalue R is formula (1):

[0044] The expression for defining the eigenvalue Y is formula (2):

[0045] Formula (1); Formula (2);

[0046] n1 represents the refractive index of the bonding unit to light;

[0047] n2 represents the refractive index of the packaging layer to light;

[0048] By adjusting n1 and n2, the value of R is set to 0.014-0.118.

[0049] H represents the thickness of the encapsulation layer;

[0050] h represents the thickness of the bonding unit.

[0051] By adjusting H and h, Y≤0.9.

[0052] In an optional embodiment, a plurality of solar cells are arranged along a first direction, and the fine grid lines of the solar cells extend along a second direction, and the first direction intersects the second direction; when installing the conductive connector, the conductive connector is laid along the first direction;

[0053] The battery string is prepared by a process of first applying glue and then welding;

[0054] Alternatively, the battery string is prepared by a process of first welding and then applying glue and curing.

[0055] In an optional embodiment, the value of R is 0.020-0.097.

[0056] In an optional embodiment, the refractive index n1 of the bonding unit to the light and the refractive index n2 of the encapsulation layer to the light satisfy: n1 <n2。

[0057] In a third aspect, the present invention provides a photovoltaic power generation device, including any photovoltaic module in the aforementioned embodiments or a photovoltaic module prepared by any preparation method in the aforementioned embodiments;

[0058] There are M photovoltaic modules, and the M photovoltaic modules are connected in series, where M is an integer not less than 1.

[0059] The present invention has the following beneficial effects: by regulating the refractive index of the bonding unit and the encapsulation layer to light, the thickness of the encapsulation layer and the height of the bonding unit, the intensity R of the reflection when the light enters the bonding unit from the encapsulation layer is controlled to be 0.014-0.118, so that the incident light is reflected very little between the bonding unit and the adhesive film interface, and by controlling the ratio of the bonding unit height to the encapsulation layer thickness Y≤0.9, it is ensured that no bubbles are formed between the bonding unit and the encapsulation layer and in the main structure, thereby improving the utilization rate of the component to the incident light, which is beneficial to improving the power of the component; the outline of the bonding unit cannot be seen in the laminated component under visual inspection, so that it is hidden in the encapsulation layer, and the aesthetic appearance of the component is enhanced. Since the number and size of the bonding units of the present invention can be maintained at the original level, the bonding strength of the glue will not be reduced, and the yield of the component is guaranteed.

[0060] It should be added that the prior art focuses more on the stability of the bonding of the bonding unit, but does not pay attention to the problem that the existence of the bonding unit (such as glue dots) will affect the aesthetics, and no prior art focuses on how to make the outline of the bonding unit invisible under visual inspection. The inventor creatively adjusts the refractive index of the bonding unit and the encapsulation layer to light, so that the refractive index of the two to light satisfies a specific relationship, achieving the technical effect of making the outline of the bonding unit invisible under visual inspection.

[0061] In addition, the inventors found that even when the characteristic value R satisfies 0.014-0.118, it is possible that glue spots can be seen under visual inspection. The inventors speculated that the above situation was caused by bubbles in the bonding unit or at the interface between the bonding unit and the film by amplifying the test results. When bubbles appear on the surface of the bonding unit or in the main structure, the reflection intensity of the interface between the bonding unit and the bubble will increase significantly, resulting in glue spots being visible under visual inspection, thereby affecting the appearance. Further, the inventors found that the height of the bonding unit and the thickness of the encapsulation layer have a significant effect on the bubbles inside the component. The inventors adjusted the thickness of the encapsulation layer and the bonding unit to a specific ratio, ensuring the technical effect that the outline of the bonding unit is invisible under visual inspection. On the basis of the above, the inventors also unexpectedly found that the photovoltaic module prepared by the present invention can further improve the power generation of the photovoltaic module while the outline of the bonding unit cannot be seen under visual inspection.

[0062] In a preferred embodiment, the present invention makes the refractive index n1 of the bonding unit to light smaller than the refractive index n2 of the packaging layer to light. The light entering the bonding unit from the adhesive film is like entering an optically sparse medium from an optically dense medium. The refracted light will move away from the normal line, allowing more incident light to reach the surface of the battery cell, thereby facilitating the improvement of component power. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0064] Figure 1 This is a cross-sectional diagram of a solder ribbon assembly fully wrapped with glue points;

[0065] Figure 2 It is a partial schematic diagram of the battery string structure;

[0066] Figure 3 A schematic diagram of the photovoltaic module structure provided in the embodiment;

[0067] Figure 4 A partial schematic diagram of a photovoltaic module structure provided in an embodiment;

[0068] Figure 5 Schematic diagram of incident light propagation (n1 <n2);

[0069] Figure 6 Schematic diagram of incident light propagation (n1>n2);

[0070] Figure 7 Schematic diagram of bubble generation;

[0071] Figure 8 This is a partial schematic diagram of the soldering tape being fully wrapped by glue points;

[0072] Fig. 9 It is a cross-sectional diagram of a solder ribbon assembly with the glue point partially wrapped;

[0073] Fig.10 This is a partial schematic diagram of the glue point partially wrapping the welding ribbon;

[0074] Fig.11 A partial schematic diagram of the photovoltaic module structure provided for Comparative Example 1.

[0075] Icons: 100-photovoltaic module; 110-cell string; 111-solar cell; 112-conductive connector; 113-adhesive unit; 120-encapsulation layer; 121-front adhesive film; 122-back adhesive film; 131-front protective substrate; 132-back protective substrate; 140-bus bar; 150-frame; 160-bubble; 161-bubble inside glue spot; 162-bubble outside glue spot. DETAILED DESCRIPTION

[0076] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0077] The prior art focuses more on the stability of the bonding of the adhesive unit, but does not pay attention to the problem that the existence of the adhesive unit (such as glue dots) will affect the aesthetics of the photovoltaic module, and no prior art focuses on how to make the outline of the adhesive unit invisible under visual inspection. The inventor creatively adjusts the refractive index of the adhesive unit and the encapsulation layer to light, so that the refractive index of the two to light satisfies a specific relationship, and at the same time adjusts the thickness of the encapsulation layer and the adhesive unit to a specific ratio, so that the outline of the adhesive unit cannot be seen under visual inspection of the photovoltaic module. At the same time, it is unexpectedly found that the power generation capacity of the photovoltaic module can be further improved. Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a photovoltaic module 100, including a battery string 110 and a packaging layer 120. The packaging layer 120 is attached to the surface of the battery string 110 to play a role of packaging protection.

[0078] The battery string 110 includes a plurality of solar cell sheets 111 and a plurality of conductive connectors 112. The plurality of solar cell sheets 111 are arranged in sequence, and two adjacent solar cell sheets 111 are conductively connected through the conductive connectors 112 to form the battery string 110. An adhesive unit 113 is also provided between the encapsulation layer 120 and the surface of the battery string 110. The conductive connector 112 is bonded to the surface of the solar cell sheet 111 by the adhesive unit 113 (such as glue dots) to improve the stability of the connection of the conductive connector 112.

[0079] The inventor creatively adjusts the refractive index of the bonding unit 113 and the encapsulation layer 120 to light, so that the refractive index of the two to light satisfies a specific relationship, thereby achieving the technical effect that the outline of the bonding unit cannot be seen under visual inspection. On this basis, the inventor unexpectedly discovered that the photovoltaic module prepared by the present invention can further improve the power generation of the photovoltaic module.

[0080] Combination Figure 3 and Figure 4As shown, since the matching of the refractive index of the encapsulation material has a great influence on the power and appearance of the module, the embodiment of the present invention adjusts the material selection of the encapsulation layer 120 and the bonding unit 113 so that the refractive index of the encapsulation layer 120 and the bonding unit 113 to light meets specific requirements, thereby making the bonding unit 113 of the prepared photovoltaic module hidden in the encapsulation layer 120 after lamination, and the outline of the bonding unit 113 is not visible on the surface. Specifically, the embodiment of the present invention defines a characteristic value R to reflect the intensity of reflection when the light is incident from the encapsulation layer 120 into the bonding unit 113, and its expression is:

[0081] ;

[0082] The characteristic value Y is defined to explain the matching relationship between the height of the bonding unit 113 and the thickness of the encapsulation layer 120, and its expression is:

[0083] ;

[0084] In the expression, n1 represents the refractive index of the bonding unit 113 to light; n2 represents the refractive index of the encapsulation layer 120 to light. By adjusting the values ​​of n1 and n2, the value of R is 0.014-0.118, such as 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, etc.

[0085] H represents the thickness of the encapsulation layer. The thickness of the encapsulation layer is the distance between the encapsulation layer position closest to the cell surface and the encapsulation layer position farthest from the cell surface on one side of the cell along the direction perpendicular to the cell. Figure 1 That is, when encapsulation layers are provided on both sides of the cell, H represents the thickness of the encapsulation layer on one side. Further, the test position of H can be selected to be 5 mm near the bonding unit 113.

[0086] h represents the height of the bonding unit, which is the distance between the bonding unit position closest to the battery cell surface and the bonding unit position farthest from the battery cell surface on one side of the battery cell along the direction perpendicular to the battery cell. Figure 5 That is to say, when bonding units are provided on both sides of the battery cell, h represents the distance that the bonding unit on one side extends in a direction perpendicular to the battery cell.

[0087] By adjusting the values ​​of H and h, Y≤0.9 is satisfied, such as 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, etc.

[0088] It should be noted that by adjusting the value of R to 0.014-0.118 and optimizing the matching of the refractive index of the cell surface bonding unit 113 and the encapsulation layer 120, the reflection intensity of the incident light between the two materials is reduced, and at the same time, the propagation direction of the incident light in the intersection area of ​​the encapsulation layer 120, the bonding unit 113 and the conductive connector 112 is controllable, so that more incident light can reach the cell surface, thereby improving the power generation of the component. In addition, by optimizing the matching of the thickness of the cell surface bonding unit 113 and the encapsulation layer 120, Y≤0.9 is made, which avoids the generation of bubbles between the two materials or in their main structure, and further improves the utilization rate of the incident light. Due to the significant reduction in reflected light, there is no obvious boundary between the glue point and the glue film, and they are visually integrated, which improves the aesthetic performance of the component.

[0089] It should be noted that when the characteristic value R<0.014, n1 and n2 are very close, and when the incident light enters the bonding unit 113 (such as the glue point) from the encapsulation layer 120, it propagates almost in a straight line and is easily blocked by the solder tape, which is not conducive to the improvement of the component power. When the characteristic value R>0.118, the outline of the glue point can be seen on the surface of the component, and the appearance value and power of the component are not the best choice.

[0090] It should be noted that when the characteristic value Y>0.9, that is, H is too small or h is too large; when the thickness H of the encapsulation layer 120 is very small, it is very easy to have insufficient film content, resulting in insufficient filling and bubbles inside the film body, affecting the performance and appearance of the component. In particular, when bubbles appear on the surface of the glue point, since the refractive index of the bubble is close to 1, the light reflection intensity R between the bubble and the glue point interface is much greater than 0.118, so part of the glue point can be seen on the surface of the component; and when the bonding unit 113 (such as the glue point) is very large, such as Figure 7 As shown, due to the particularity of the printing process, the glue dot can easily carry bubbles into its body, resulting in bubbles 160 (including bubbles 161 inside the glue dot and bubbles 162 outside the glue dot). At the same time, since the bonding unit 113 is too large, the narrow gap between the solder tape and the glue dot is not easy to fill, bubbles will also appear, and then the glue dot can be seen, which is not conducive to component performance.

[0091] In a preferred embodiment, by adjusting the values ​​of n1 and n2, the value of R is set to 0.020-0.097. If the value of R is controlled within the above range, the battery efficiency can be further improved without visible glue spots on the component surface.

[0092] In a preferred embodiment, in order to better optimize the matching degree between the adhesive film and the glue and improve the utilization rate of the incident light source, the refractive index n1 of the bonding unit 113 for light and the refractive index n2 of the encapsulation layer 120 for light satisfy: n1 < n2. When n1 and n2 satisfy n1 < n2, the encapsulation layer 120 is equivalent to an optically denser medium, while the bonding unit 113 is equivalent to an optically rarer medium. When light travels from an optically denser medium to an optically rarer medium, the refracted light will deviate from the normal, as Figure 5 shown. Under this condition, more incident light can reach the surface of the battery cell, which is conducive to improving the power of the module.

[0093] Conversely, the schematic diagram of light propagation when n1 > n2 is as shown in Figure 6 shown, and the incident light will approach the normal, which is likely to cause solder strip occlusion and is not conducive to improving the power of the module.

[0094] In some embodiments, the refractive index n1 of the bonding unit 113 for light is 1.35 - 1.60, such as 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, etc. The refractive index of the glue used to form the bonding unit 113 for light is basically the same as that of the finally formed bonding unit 113 for light. That is to say, the refractive index of the glue used to form the bonding unit 113 for light also satisfies the value range of 1.35 - 1.60. The glue used to form the bonding unit 113 is selected from at least one of silicone glue, acrylic glue, and epoxy resin glue, and the glue can be any one or several of the above.

[0095] Furthermore, the refractive index n2 of the encapsulation layer 120 for light is 1.40 - 1.65, such as 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, etc. The encapsulation layer 120 is formed by laminating and cross-linking the encapsulation adhesive film. The encapsulation adhesive film is selected from at least one of POE encapsulation adhesive film (polyolefin elastomer), EVA encapsulation adhesive film (ethylene-vinyl acetate copolymer), and EPE encapsulation adhesive film (co-extrusion of POE and EVA). The encapsulation layer 120 can be formed by laminating and cross-linking any one or several of the above encapsulation adhesive films.

[0096] It should be noted that if the refractive index n1 of the bonding unit 113 for light is too low or too high (<1.35 or >1.65), a large amount of substances with low refractive index or high refractive index need to be introduced for modification, which has a greater impact on other properties of the glue.

[0097] In some embodiments, the height of the bonding unit is 50-280 μm, specifically 50 μm, 80 μm, 100 μm, 130 μm, 150 μm, 180 μm, 200 μm, 230 μm, 250 μm, 280 μm, etc.; the thickness of the encapsulation layer is 300-400 μm, such as 300 μm, 330 μm, 350 μm, 380 μm, 400 μm, etc.

[0098] In the embodiment of the present invention, the refractive index n1 of the bonding unit 113 to light and the refractive index n2 of the encapsulation layer 120 to light are adjusted to meet a specific relationship, and the ratio Y of the bonding unit height to the encapsulation layer thickness is controlled to meet a specific value, so that the existence of glue spots cannot be detected on the component surface. In actual operation, the following method can be used to determine whether glue spots can be detected:

[0099] Use a camera to capture the component surface, obtain the grayscale values ​​of different areas, and calculate the eigenvalue G:

[0100] G = |g2-g1|;

[0101] Among them, the characteristic value G is the gray value threshold, g1 is the gray value of the area without adhesive unit 113 on the surface of the photovoltaic module 100 (such as the surface area of ​​the solar cell 10mm near the adhesive unit 113), and g2 is the gray value of the area with adhesive unit 113 on the surface of the photovoltaic module 100; when G>20, the glue point can be detected; when G≤20, the glue point cannot be detected. The photovoltaic module provided by the embodiment of the present invention adopts the above method for detection, and satisfies G≤20.

[0102] In some embodiments, the conductive connector 112 may be a solder strip. The material of the solder strip is not limited and may be a copper wire. Specifically, a commercially available copper wire with a tin-lead solder plated surface may be used.

[0103] In some embodiments, the bonding unit 113 can be a glue point or segment formed by curing glue, or a combination of the two. The curing method can be lamp radiation heating curing, ultraviolet light irradiation curing, or infrared light heating curing. The type of glue is not limited. The position of the glue point corresponds to the position of the soldering strip. A soldering strip is bonded to the solar cell panel 111 through multiple glue points arranged at intervals.

[0104] Please refer again Figure 1 , Figure 2 and Figure 4, multiple solar cell sheets 111 are arranged at intervals, one side of the solar cell sheet 111 is connected to the reverse side of another adjacent solar cell sheet 111 through a conductive connector 112, so as to realize the series connection of the solar cell sheets 111, and bonding units 113 are provided on both sides of the surface of the battery string 110. The conductive connector 112 extends from one end of the arrangement direction of the solar cell sheets 111 to the other opposite end; in another direction perpendicular to the arrangement direction, multiple conductive connectors 112 are arranged at intervals.

[0105] For some types of solar cells, such as back-contact BC cells, only one side of the surface of the cell string 110 is provided with a conductive connector, and correspondingly, only one side of the surface of the cell string 110 is provided with an adhesive unit 113 .

[0106] In some embodiments, Figure 1 As shown, the front and back sides of the solar cell sheet 111 are both provided with conductive connectors 112 and adhesive units 113, and the encapsulation layer 120 includes a front adhesive film 121 and a back adhesive film 122, the front adhesive film 121 is attached to the front side of the battery string 110, and the back adhesive film 122 is attached to the back side of the battery string 110. When the front and back sides of the solar cell sheet 111 are both provided with conductive connectors 112 and adhesive units 113, the front side of the battery string 110 is encapsulated by the front adhesive film 121, and the back side of the battery string 110 is encapsulated by the back adhesive film 122.

[0107] It should be added that when the front and back sides of the solar cell 111 are both provided with conductive connectors 112 and adhesive units 113, and the encapsulation layer 120 includes a front adhesive film 121 and a back adhesive film 122, at least the following conditions are satisfied: when light is incident from the front adhesive film 121 into the adhesive unit 113, the reflection ratio R is 0.014-0.118, ensuring that the glue points are hidden in the adhesive film when viewed from the front side of the component.

[0108] In some embodiments, the photovoltaic module 100 also includes a front protective substrate 131 and a back protective substrate 132. The front protective substrate 131 is bonded to the end surface of the front adhesive film 121 away from the battery string 110, and the back protective substrate 132 is bonded to the end surface of the back adhesive film 122 away from the battery string 110. The front protective substrate 131 and the back protective substrate 132 can be transparent substrates to protect the front and back sides.

[0109] The material of the front protection substrate 131 can be glass, which can improve the light transmittance.

[0110] The material of the back protection substrate 132 can be glass, a polymer material, or a mixture of the two. When the material of the back protection substrate 132 is a polymer material, it can be at least one of polyethylene terephthalate, polyolefin copolymer, polyamide, polyvinyl fluoride and polyvinylidene fluoride.

[0111] In some embodiments, the photovoltaic module 100 may further include a frame 150 and a bus bar 140 . The frame 150 protects the periphery of the module, and adjacent battery strings are connected by the bus bar 140 to form a circuit unit.

[0112] In order to match and optimize different component preparation process windows and component application scenarios, a full wrap is usually formed between the glue point and the solder ribbon (such as Figure 1 and Figure 8 as shown) and some packages (as Fig. 9 and Fig.10 shown).

[0113] like Figure 1 and Figure 8 As shown, at the location of the bonding unit 113, the bonding unit 113 covers the surface of the conductive connector 112. At this time, the bonding unit 113 completely covers the surface of the conductive connector 112. When the process of welding first and then applying glue and curing is adopted, the following will be formed: Figure 8 The glue dots shown completely cover the surface of the conductive connector 112 .

[0114] In another embodiment, Fig. 9 and Fig.10 As shown in FIG. 1 , at the location of the bonding unit 113, the bonding unit 113 is located between the conductive connector 112 and the solar cell sheet 111, and the bonding unit 113 covers a portion of the surface of the conductive connector 112, and no covering is formed on the surface of the conductive connector 112 away from the solar cell sheet 111. Specifically, when the conductive connector 112 is fixed by first applying glue and then welding, or when the conductive connector 112 is fixed by only applying glue, the following structure will be formed: Fig.10 The glue dots shown partially cover the conductive connector 112 .

[0115] An embodiment of the present invention also provides a method for preparing a photovoltaic module, comprising: arranging a conductive connector 112 on at least one side surface of a plurality of solar cells 111 in a thickness direction, and bonding the conductive connector 112 and the solar cell 111 via a bonding unit 113 to form a cell string 110; and then encapsulating the cell string 110 using an encapsulation layer 120.

[0116] During the preparation process, the refractive index of the encapsulation layer 120 and the glue to the light and their own thickness are matched, and the characteristic value R is defined to reflect the intensity of the reflection when the light is incident from the encapsulation layer 120 to the bonding unit 113, and its expression is formula (1): The characteristic value Y is defined to describe the matching relationship between the encapsulation layer 120 and the bonding unit 113 in thickness, and its expression is formula (2):

[0117] Formula (1);

[0118] Formula (2);

[0119] n1 represents the refractive index of the bonding unit 113 to light;

[0120] n2 represents the refractive index of the encapsulation layer 120 to light;

[0121] By adjusting n1 and n2, the value of R is set to 0.014-0.118.

[0122] The value of Y satisfies Y≤0.9;

[0123] H represents the thickness of the encapsulation layer, which is the distance between the encapsulation layer position closest to the battery cell surface and the encapsulation layer position farthest from the battery cell surface on one side of the battery cell along the direction perpendicular to the battery cell.

[0124] h represents the height of the bonding unit, which is the distance between the bonding unit position closest to the battery cell surface and the bonding unit position farthest from the battery cell surface on one side of the battery cell along the direction perpendicular to the battery cell.

[0125] It should be noted that during the preparation process, by adjusting the refractive index n1 of the encapsulation layer 120 and the refractive index n2 of the bonding unit 113 to light, the two can be better matched, so that the outline of the glue point can be invisible on the component surface, which is beneficial to improving the efficiency of the component.

[0126] In some embodiments, a plurality of solar cell sheets 111 are arranged along a first direction, and the fine grid lines of the solar cell sheets 111 extend along a second direction, and the first direction intersects the second direction; when installing the conductive connector 112, the conductive connector 112 is laid along the first direction. The preparation process of the battery string can adopt a welding glue dispensing process, and the battery string 110 can be prepared by a process of first dispensing glue and fixing and then welding, or by a process of first welding and then dispensing glue and curing. The specific preparation steps can refer to the existing technology.

[0127] An embodiment of the present invention further provides a photovoltaic power generation device, including the photovoltaic module 100 provided in the embodiment of the present invention. The photovoltaic modules 100 may be M in number, and the M photovoltaic modules 100 are connected in series, where M is an integer not less than 1, and the specific number can be adjusted according to process requirements.

[0128] In some embodiments, the photovoltaic power generation device may further include an inverter, and the output end of the photovoltaic power generation device is connected to the input end of the inverter for photovoltaic power generation.

[0129] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0130] Example 1

[0131] This embodiment provides a method for preparing a photovoltaic module, and the specific steps are as follows:

[0132] (1) Preparation of materials

[0133] Accurate glue: commercially available organic silica gel (purchased from Delangju New Materials Co., Ltd., model SE-6002), the refractive index n1 of light at 25±1°C after curing is 1.42.

[0134] Prepare encapsulation film (front and back): the front encapsulation film is a commercially available EPE encapsulation film (purchased from Hangzhou Foster Applied Materials Co., Ltd., model EP304), and the back encapsulation film is a commercially available EVA encapsulation film (purchased from Hangzhou Foster Applied Materials Co., Ltd., model F406P). After lamination, the refractive index n2 of light at 25±1°C is 1.48.

[0135] Prepare solder strip: Purchase copper wire with tin-lead solder on the surface, the solder layer thickness is 15 μm, and the copper wire diameter is 0.22 mm.

[0136] Solar cells: busbarless crystalline silicon solar cells (produced by Tongwei Solar (Meishan) Co., Ltd., model SY11), with dimensions of 210mm*210mm and thickness of 130μm; half-cell dimensions of 210mm*105mm.

[0137] Flux: purchased from Shaoxing Tuobang New Energy Co., Ltd., model FC10V16-6.

[0138] Busbar: Commercially available flat reflective busbar made of tinned copper strip.

[0139] Front glass (ie, front protective substrate 131 ): commercially available double-coated glass.

[0140] Back glass (ie, back protective substrate 132 ): commercially available non-glazed transparent three-hole glass with a hole diameter of 12 mm.

[0141] (2) Preparation of battery strings

[0142] Print a proper amount of glue on the front and back of 11 half-cell batteries in turn, with a spacing of 10mm between adjacent glue printing positions. Then soak the soldering tape in the flux solution for 1s and arrange them on the corresponding glue surfaces. The direction of the soldering tape is parallel to the short side of the half-cell battery. Use the soldering tape to connect the positive and negative electrodes of adjacent battery cells in turn. Finally, alloy the soldering tape with the battery surface under the light box of the welding machine, and cure the glue at the same time.

[0143] (3) Packaging

[0144] The front glass, front encapsulation film, battery string, back film, and back glass are stacked in sequence, and adjacent battery strings are connected by bus bars, and then laminated to melt and cross-link the film to obtain a packaged battery string. Finally, the edge trimming and frame mounting processes are performed to obtain the finished component.

[0145] A partial picture of the photovoltaic module prepared in Example 1 is shown in FIG. Figure 4 As shown, the outline of the glue point cannot be seen under visual inspection of the PV module.

[0146] Embodiment 2-6

[0147] The only difference from Example 1 is that the refractive index n1 of the glue to the light and the refractive index n2 of the packaging film to the light are different, see Table 1 for details.

[0148] Examples 7-10

[0149] The only difference from Example 3 is that the thickness H of the adhesive film after lamination and the thickness h of the adhesive after curing are different, see Table 1 for details.

[0150] Comparative Examples 1-6

[0151] The only difference from Example 1 is that the refractive index n1 of the glue to light, the refractive index n2 of the packaging film to light, the thickness H of the film after lamination, and the thickness h of the glue after curing are different, as shown in Table 1 for details.

[0152] The partial picture of the photovoltaic module prepared in the comparative example is as follows Fig.11 As shown, the presence of glue spots can be clearly seen.

[0153] Test Example 1

[0154] The performance of the photovoltaic modules prepared in the test examples and comparative examples is shown in Table 1.

[0155] Test method:

[0156] (1) Glue point detection: Glue point contour detection method after component lamination. First, use a camera to capture the component surface, and then obtain the grayscale values ​​of different areas according to the set algorithm program or software such as R3 and Lμmi Tools. The specific description is as follows:

[0157] G = |g2-g1|;

[0158] Among them, the characteristic value G is the gray value threshold, g1 is the gray value of the area without glue spots on the component surface, and g2 is the gray value of the area with glue spots on the component surface. When G>20, the glue spots can be detected; when G≤20, the glue spots cannot be detected.

[0159] (2) Refractive index test: First, cure or laminate the commercially available glue or film at the process temperature, cool it to room temperature (25℃±1℃) to obtain the sample to be tested, and then test the refractive index of the sample using a refractive index test instrument (such as Abbe refractometer) at an ambient temperature of 25±1℃.

[0160] (3) Performance testing: The power generation capacity is tested using the IEC 61215 standard.

[0161] Table 1 Performance test results of photovoltaic modules prepared in Examples and Comparative Examples

[0162]

[0163] It can be seen that if the values ​​of the characteristic values ​​R and Y exceed the range specified in this application, the power generation of the component will decrease, and at the same time, the presence of glue spots can be detected on the surface, which is not conducive to improving the aesthetics of the component.

[0164] By comparing Examples 1-6, it can be found that as R increases, the power first increases and then decreases. The preferred embodiments are Examples 2-4, and the preferred value range of R is 0.020-0.097.

[0165] Comparing Example 3 with Examples 7-10, when the values ​​of H, h and Y are within the range, the value of Y does not affect the power, and the technical effect of invisible glue spots can be achieved. Comparing Examples 3 and 11, although the characteristic values ​​R and Y are the same, due to n1>n2 in Example 11, the light transmission path will move closer to the solder strip (such as Figure 6 ), resulting in shading, thereby reducing the power generation of the component. Although the Y value of Example 12 is within the range, due to the excessive height of the glue dot, the gas is entrained into the glue during the printing process, resulting in bubbles inside the glue dot after lamination. The reflection intensity of the bubble and the glue dot interface is relatively large, and the glue dot can be seen under visual inspection.

[0166] In Comparative Example 1, the values ​​of n1 and n2 are close, and the R value is too small, resulting in the light being blocked by the solder tape; in Comparative Example 2, the difference between n1 and n2 is large, resulting in a large R value, and both Comparative Examples 1-2 result in low power. In addition, in Comparative Example 2, the glue point can be seen because R is too large, and the glue point can also be detected in Comparative Example 3 because the R value is too large. In Comparative Example 4, the Y value is too large, the height of the glue point is too large, and the thickness of the glue film is too small, which easily leads to poor filling of the glue film and the appearance of bubbles on the surface of the glue point, thereby increasing the reflection intensity of the light on the surface of the glue point, so the glue point can be seen.

[0167] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A photovoltaic module, characterized in that: include: A battery string, wherein the battery string comprises a plurality of solar cells and a plurality of conductive connectors, and adjacent solar cells are conductively connected through the conductive connectors; An encapsulation layer, the encapsulation layer being attached to a surface of the battery string; A bonding unit is also provided between the encapsulation layer and the surface of the battery string, and the bonding unit bonds the conductive connector to the surface of the solar cell sheet; The expression for defining the eigenvalue R is formula (1): The expression for defining the eigenvalue Y is formula (2): Formula (1); Formula (2); The value of R is 0.014-0.118; n1 represents the refractive index of the bonding unit to light; n2 represents the refractive index of the encapsulation layer to light; The value of Y satisfies Y≤0.9; H represents the thickness of the encapsulation layer; h represents the height of the bonding unit; The height of the bonding unit is 50-280 μm.

2. The photovoltaic module according to claim 1, characterized in that: The value of R is 0.020-0.

097.

3. The photovoltaic module according to claim 1 or 2, characterized in that: The refractive index n1 of the bonding unit to light and the refractive index n2 of the encapsulation layer to light satisfy: n1 <n2。 4. The photovoltaic module according to claim 1 or 2, characterized in that: The bonding unit is provided on only one side of the surface of the battery string or on both sides of the surface of the battery string; And / or, the bonding unit is formed by curing glue.

5. The photovoltaic module according to claim 4, characterized in that: The refractive index n1 of the bonding unit to light is 1.35-1.60; And / or, the glue used to form the bonding unit is selected from at least one of organic silicone glue, acrylic glue and epoxy resin glue.

6. The photovoltaic module according to claim 3, characterized in that: The refractive index n2 of the encapsulation layer to light is 1.40-1.65, and the thickness of the encapsulation layer is 300-400 μm; And / or, the encapsulation layer is formed by laminating and cross-linking an encapsulation film, and the encapsulation film is selected from at least one of a POE encapsulation film, an EVA encapsulation film and an EPE encapsulation film.

7. The photovoltaic module according to claim 1, characterized in that: Use a camera to capture the component surface, obtain the grayscale values ​​of different areas, and calculate the eigenvalue G: G = |g2-g1|; Among them, the characteristic value G is the gray value threshold, g1 is the gray value of the area without bonding unit on the surface of the photovoltaic module, and g2 is the gray value of the area with bonding unit on the surface of the photovoltaic module; The value of G satisfies: G≤20.

8. The photovoltaic module according to claim 1, characterized in that: At the location of the bonding unit, the bonding unit covers the surface of the conductive connecting member.

9. The photovoltaic module according to claim 1, characterized in that: At the location of the bonding unit, the bonding unit is located between the conductive connecting member and the solar cell sheet, and the bonding unit covers a portion of the surface of the conductive connecting member.

10. The photovoltaic module according to claim 1, characterized in that: The front and back sides of the solar cell sheet are both provided with the conductive connector and the bonding unit, the encapsulation layer comprises a front adhesive film and a back adhesive film, the front adhesive film is attached to the front side of the cell string, and the back adhesive film is attached to the back side of the cell string; At least the following conditions are met: the characteristic value R is 0.014-0.118; the ratio of the height of the bonding unit to the thickness of the front adhesive film Y≤0.9; And / or, the conductive connecting member is a welding strip.

11. The photovoltaic module according to claim 10, characterized in that: A plurality of solar cell sheets are arranged at intervals, and one side of a solar cell sheet is connected to the reverse side of another adjacent solar cell sheet through the conductive connector.

12. The photovoltaic module according to claim 10, characterized in that: It also includes a front protection substrate and a back protection substrate. The front protection substrate is bonded to the end face of the front adhesive film away from the battery string, and the back protection substrate is bonded to the end face of the back adhesive film away from the battery string.

13. The photovoltaic module according to claim 12, characterized in that: The material of the front protection substrate is glass; And / or, the material of the back protection substrate is selected from at least one of glass and high molecular polymer materials, wherein the high molecular polymer material includes polyethylene terephthalate, polyolefin copolymer, polyamide, polyvinyl fluoride and polyvinylidene fluoride.

14. A method for preparing a photovoltaic module, characterized in that: include: Arranging a conductive connector on at least one side surface of a plurality of solar cell sheets in a thickness direction, and bonding the conductive connector and the solar cell sheets by a bonding unit to form a cell string; and encapsulating the cell string by an encapsulation layer; The expression for defining the eigenvalue R is formula (1): The expression for defining the eigenvalue Y is formula (2): Formula (1); Formula (2); n1 represents the refractive index of the bonding unit to light; n2 represents the refractive index of the encapsulation layer to light; By adjusting n1 and n2, the value of R is set to 0.014-0.118; H represents the thickness of the encapsulation layer; h represents the height of the bonding unit; The height of the bonding unit is 50-280 μm; By adjusting H and h, Y≤0.

9.

15. The preparation method according to claim 14, characterized in that: Arrange the plurality of solar cell sheets along a first direction, the fine grid lines of the solar cell sheets extend along a second direction, and the first direction intersects with the second direction; when installing the conductive connector, lay the conductive connector along the first direction; The battery string is prepared by a process of first applying glue and then welding; Alternatively, the battery string is prepared by a process of first welding and then applying glue and curing.

16. The preparation method according to claim 14, characterized in that: The value of R is 0.020-0.

097.

17. The preparation method according to claim 14 or 16, characterized in that: The refractive index n1 of the bonding unit to light and the refractive index n2 of the encapsulation layer to light satisfy: n1 <n2。 18. A photovoltaic power generation device, characterized in that: A photovoltaic module comprising any one of claims 1 to 13 or a photovoltaic module prepared by the preparation method of any one of claims 14 to 17; There are M photovoltaic modules, and the M photovoltaic modules are connected in series, where M is an integer not less than 1.

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