Photovoltaic module and photovoltaic system

Abstract

The invention discloses a photovoltaic module and a photovoltaic system, the photovoltaic module comprises a plurality of battery pieces and a packaging adhesive film at least arranged on one side of the battery pieces, and each battery piece comprises a plurality of fine grids which extend along a first direction and are arranged at intervals along a second direction; the fine grid is in a fluctuating shape in the thickness direction, the fluctuating fine grid is provided with a plurality of first wave crests and a plurality of first wave troughs which are arranged in the first direction, the packaging adhesive film combined with the fine grid is provided with convex parts and concave parts, the concave parts are in contact with the first wave crests, the convex parts are embedded into the first wave troughs, and the fine grid and the packaging adhesive film are mutually embedded to form an interdigital structure. According to the embodiment of the invention, the oxidation risk of the fine grid can be reduced, and the reliability of the photovoltaic module is ensured.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to a photovoltaic module and a photovoltaic system. Background Technology

[0002] A photovoltaic module includes a cell string, which includes multiple cells and solder strips that electrically connect the multiple cells.

[0003] To save costs, copper can be used for the grid lines of solar cells. However, copper grid lines are prone to oxidation, and the oxidation of copper grid lines will be further aggravated after external moisture enters the module, thus affecting the reliability of photovoltaic modules.

[0004] How to reduce the oxidation risk of base metal grid lines during the service life of photovoltaic modules and ensure the reliability of photovoltaic modules is an urgent problem to be solved. Summary of the Invention

[0005] This invention provides a photovoltaic module and a photovoltaic system, which aims to reduce the oxidation risk of base metal grid lines and ensure the reliability of the photovoltaic module.

[0006] This invention provides a photovoltaic module, including a plurality of solar cells and an encapsulating film disposed at least on one side of the solar cells. The solar cells include a plurality of fine grids extending along a first direction and spaced apart along a second direction. The main conductive material of the fine grids includes copper, aluminum, nickel, iron, zinc, tin or tungsten. The fine grid is undulating in the thickness direction. The undulating fine grid has multiple first peaks and multiple first valleys arranged along the first direction. The encapsulating film combined with the fine grid has protrusions and depressions. The depressions are in contact with the first peaks, and the protrusions are embedded in the first valleys. The fine grid and the encapsulating film are interlocked to form an interdigitated structure.

[0007] In this embodiment of the invention, the undulating fine grid has multiple first peaks and multiple first troughs arranged along a first direction. The recessed portion of the encapsulating film combined with the fine grid contacts the first peak, and the protrusion is embedded in the first trough. At this time, the base metal fine grid and the encapsulating film form an interdigitated structure through the interlocking of the first peak, the first trough and the protrusion and recess, which can increase the bonding area between the two and reduce the exposed area of ​​the fine grid, thereby reducing the risk of fine grid oxidation. Moreover, compared with planar contact, the interdigitated structure can increase the bonding force and bonding performance between the fine grid and the encapsulating film, effectively prevent moisture from entering between the fine grid and the encapsulating film, and reduce the risk of moisture intrusion caused by pull-out and separation between the fine grid and the encapsulating film, thereby effectively improving the fine grid oxidation problem and ensuring the reliability of the photovoltaic module.

[0008] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other objects, features and advantages of the present invention more obvious and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the layer structure of a photovoltaic module provided in an embodiment of the present invention; Figure 2 This is a partial schematic diagram of a battery cell provided in an embodiment of the present invention; Figure 3 A partial schematic diagram of another type of battery cell provided in an embodiment of the present invention; Figure 4 This is a partial schematic diagram of a fine grid in a photovoltaic module provided by an embodiment of the present invention; Figure 5 This is a schematic diagram illustrating the combination of the grid and encapsulating film of a solar cell in a photovoltaic module, as provided in an embodiment of the present invention. Figure 6 for Figure 5 Enlarged view of point A in the middle; Figure 7 This is a partial cross-sectional schematic diagram of an encapsulating film in a photovoltaic module provided by an embodiment of the present invention; Figure 8 This is a schematic diagram illustrating the combination of the fine grid and encapsulating film in a solar cell of another photovoltaic module provided by an embodiment of the present invention. Figure 9 This is a schematic diagram illustrating the connection between the cell connector and the conductive layer in a photovoltaic module, provided by an embodiment of the present invention. Figure 10 This is a partial cross-sectional schematic diagram of a battery cell provided in an embodiment of the present invention.

[0010] Figure label: 10-Battery cell, 11-Battery body, 111-Passivation layer, 12-Fine grid, 121-First peak, 122-First trough, 13-Connector, 131-Second peak, 132-Second trough, 14-End line; 20-Conductive layer, 30-Insulator, 40-Front glass, 51-First encapsulating film, 52-Second encapsulating film, 53-Protrusion, 54-Recess, 60-Back glass; F - First peak, G - First valley. Detailed Implementation

[0011] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0012] This invention provides a photovoltaic system. The photovoltaic system includes multiple photovoltaic modules electrically connected together. These photovoltaic modules are arranged in an array. The specific installation location of the photovoltaic system is not limited and can be used on rooftops, walls, deserts, wastelands, seashores, mountains, agricultural sites, etc.

[0013] Reference Figure 1 This invention discloses a photovoltaic module. The photovoltaic module includes a plurality of solar cells 10 and an encapsulating film disposed at least on one side of the solar cells 10. The photovoltaic module may include a front glass 40, a first encapsulating film 51, a cell matrix, a second encapsulating film 52, and a back glass 60 stacked sequentially. The cell matrix may include a plurality of cell strings electrically connected together. The cell strings include a plurality of solar cells 10 and interconnecting members for connecting the plurality of solar cells 10 in series. The back glass 60 may be replaced by a backsheet. The encapsulating film may be made of EVA (ethylene-vinyl acetate copolymer) or POE (polyolefin elastomer) or a combination of both.

[0014] The photovoltaic module can be manufactured as follows: multiple solar cells 10 are connected in series to form a cell string via interconnects; a front glass 40 and a first encapsulating film 51 are sequentially laid; multiple cell strings are arranged into a cell matrix on the first encapsulating film 51, and electrical connections and fixation are made between the cell strings; a second encapsulating film 52 and a back glass 60 are sequentially laid on the cell matrix; the above-mentioned laminated structure is subjected to high-temperature lamination to obtain a photovoltaic laminate. Alternatively, the front glass 40 and the first encapsulating film 51 can be laid first, and then all the solar cells 10 of the cell matrix can be placed on the first encapsulating film 51 and electrically connected and fixed.

[0015] Reference Figure 2 and Figure 3The battery cell 10 includes a plurality of fine grids 12 extending along a first direction and spaced apart along a second direction, the first direction being the X-direction in the figure, and the second direction being the Y-direction in the figure. The main conductive material of the fine grids 12 is a base metal. When the fine grids include multiple conductive materials, the main conductive material can be the conductive material that accounts for more than 1% of all components of the fine grids and is among the top three conductive materials in terms of content. When the fine grids contain a single conductive material, that single conductive material is the main conductive material. Base metals mainly refer to metals that are easily oxidized and corroded, such as copper, aluminum, nickel, iron, zinc, tin, tungsten, etc. The base metal fine grids can be screen-printed onto the battery body 11 using a paste, or they can be fabricated onto the battery body 11 using processes such as printing, sputtering, or vapor deposition.

[0016] Reference Figure 2 and Figure 3 The solar cell 10 also includes a battery body 11, with fine grids 12 fixed to the battery body 11. Specifically, the fine grids 12 can be a paste cured on the battery surface, or the fine grids 12 can be burned through the surface of the battery body 11 and contact the underlying conductive layer. The solar cell 10 can be a back-contact solar cell, in which case both the positive and negative fine grids are fixed to the back side of the battery body 11. The solar cell 10 can also be a bifacial solar cell, such as a TOPcon (Tunnel Oxide Passivated Contact) solar cell or an HJT (Heterojunction with Intrinsic Thin-layer) solar cell, in which case the fine grids 12 are fixed to both the front and back sides of the battery body 11. The solar cell 10 can be a gridless solar cell or a solar cell with a main grid. The solar cell 10 can be a half-cell, three-quarter-cell, four-quarter-cell, five-quarter-cell, six-quarter-cell, etc.

[0017] Reference Figures 4 to 6 The fine grid 12 is undulating in the thickness direction. The undulating fine grid 12 has multiple first peaks 121 and multiple first valleys 122 arranged along the first direction. The highest point of the first peak 121 is the first peak F, and the lowest point of the first valley 122 is the first valley bottom G. The first peak F can be point-like or surface-like, and the first valley bottom G can be point-like or surface-like.

[0018] The first peak 121 is the portion that protrudes towards the encapsulating film relative to the surrounding area, and the first trough 122 is the portion that is recessed towards the battery body 11 relative to the surrounding area. The first trough 122 at non-end points is located between two adjacent first peaks 121. At the end of the fine grid 12, the first trough 122 may be located between two adjacent first peaks 121, or it may be located on one side of a first peak 121.

[0019] Reference Figures 5 to 7The encapsulating film combined with the fine grid 12 has protrusions 53 and recesses 54. The recesses 54 contact the first peak 121, and the protrusions 53 are embedded in the first trough 122. Multiple protrusions 53 and multiple recesses 54 corresponding to one fine grid 12 are arranged along a first direction, and the fine grid 12 and the encapsulating film are interlocked to form an interdigitated structure. In the production process, by adjusting the slurry of the fine grid 12, its leveling properties, particle size, and filler shape are adjusted to form undulating fine grids 12 and reduce the protrusions at the top of the fine grid 12. At the same time, by adjusting the material of the encapsulating film, the fluidity of the encapsulating film can be improved and the viscosity of the encapsulating film can be reduced, so that the encapsulating film can be embedded into the first trough 122. The combined improvement of both the fine grid 12 and the encapsulating material is conducive to the formation of the interdigitated structure. It should be understood that under certain operating conditions, even if the fine grid 12 has an uneven structure, if the encapsulating film has insufficient fluidity, the encapsulating film cannot be embedded in the first trough 122, and the interdigitated structure cannot be formed. Alternatively, if the unevenness of the fine grid 12 is too small, or if there are too many protrusions and the opening is too small, the encapsulating film cannot be successfully embedded in the first trough 122 to form the interdigitated structure.

[0020] In some embodiments, refer to Figure 5 and Figure 6 The battery cell 10 is a back-contact battery cell, the fine grid 12 is provided on the back side of the battery body 11, and the encapsulation film with protrusions 53 and recesses 54 is provided on the back side of the battery cell 10. The encapsulation film with protrusions 53 and recesses 54 is the second encapsulation film 52.

[0021] In some embodiments, refer to Figure 8 The battery cell 10 is a double-sided battery cell, and there are two encapsulation films with protrusions 53 and recesses 54. The two encapsulation films are respectively disposed on the front and back sides of the battery cell 10. The two encapsulation films are the first encapsulation film 51 and the second encapsulation film 52.

[0022] In this embodiment of the invention, the undulating fine grid 12 has multiple first peaks 121 and multiple first troughs 122 arranged along a first direction. The recessed portion 54 of the encapsulating film combined with the fine grid 12 contacts the first peaks 121, and the protrusions 53 are embedded in the first troughs 122. At this time, the base metal fine grid and the encapsulating film form an interdigitated structure through the mutual embedding of the first peaks 121, the first troughs 122, the protrusions 53, and the recesses 54. This can increase the bonding area between the two and reduce the exposed area of ​​the fine grid 12, thereby reducing the risk of oxidation of the fine grid 12. Moreover, compared with planar contact, the interdigitated structure can increase the bonding force and bonding performance between the fine grid 12 and the encapsulating film, effectively prevent moisture from entering between the fine grid 12 and the encapsulating film, and reduce the risk of moisture intrusion caused by pull-out or separation between the fine grid 12 and the encapsulating film. This can effectively improve the oxidation problem of the fine grid 12 and ensure the reliability of the photovoltaic module.

[0023] In some embodiments, refer to Figure 2 and Figure 3 The solar cell 10 is a back-contact solar cell, and the grid 12 is disposed on the back side of the solar cell body 11. The grid 12 includes multiple positive and negative grids, which are arranged alternately along a second direction. The photovoltaic module also includes an insulating element 30, which is disposed on the grid 12. The insulating element 30 enables insulation between the interconnects and the grid 12.

[0024] The forming process of the fine grid 12 can be as follows: the paste is printed onto the battery body 11, and after a sintering process, the fine grid 12 is formed. By adjusting the paste of the fine grid 12, for example, adjusting the particle size and organic content of the paste, the surface of the fine grid 12 can form a smoother uneven structure without protrusions exceeding 30μm. The smoother first peak 121 is less likely to puncture the insulating component 30, thereby preventing short circuits caused by the electrical connection between the irregular fine grid and the interconnecting component due to the puncture of the insulating component 30. Alternatively, the forming process parameters of the fine grid 12 can be adjusted to form a smoother uneven structure on the surface of the fine grid 12, preventing the first peak F from being too sharp.

[0025] In some embodiments, refer to Figure 7 The encapsulating film has a height difference S1 between a set of adjacent protrusions 53 and recesses 54, with S1 ranging from 5μm to 15μm. When S1 is within this range, it ensures that the encapsulating film is embedded more deeply into the base metal grid. The encapsulating film and the grid 12 form a deeper interdigitated structure. Compared to the encapsulating film only filling the opening of the first trough 122, the deeper interdigitation increases the contact between the encapsulating film and the sidewall of the inclined first trough 122, thereby increasing the friction and contact area between the two. This better ensures the bonding performance between the encapsulating film and the grid 12 and reduces the risk of separation and moisture intrusion.

[0026] S1 is the distance between the highest point of the protrusion 53 and the lowest point of the recess 54 along the thickness direction of the battery cell 10. (Refer to...) Figure 4 The first peak 121 and the first trough 122, which correspond to a set of adjacent protrusions 53 and recesses 54, have a height difference S2, which is 5μm-15μm. S2 is the distance between the first peak F of the first peak 121 and the first valley bottom G of the adjacent first valley 122 along the thickness direction of the battery cell 10.

[0027] It should be noted that although S1 and S2 have the same range, S2 is equal to S1 only when the protrusion 53 completely fills the first trough 122. When the protrusion 53 does not completely fill the first trough 122, S1 is less than S2.

[0028] Reference Figure 4 and Figure 6 The height difference S2 between a set of adjacent first peaks 121 and first valleys 122 is also the difference between the height H1 of the first peak 121 and the height H2 of the adjacent first valley bottom G. The height H1 of the first peak 121 is the distance between the first peak F and the surface of the battery body 11 with fine grids 12 along the thickness direction of the battery cell 10. The height H2 of the first valley bottom G is the distance between the first valley bottom G and the surface of the battery body 11 with fine grids 12 along the thickness direction of the battery cell 10. The height H2 of the first valley bottom G can be between 2μm and 15μm.

[0029] The battery cell 10 includes multiple fine grids 12, and the encapsulating film has multiple strip-shaped undulating regions corresponding one-to-one with the multiple fine grids 12. Each strip-shaped undulating region has multiple protrusions 53 and multiple recesses 54 arranged along a first direction. The height difference S1 between a group of adjacent protrusions 53 and recesses 54 at different positions within the same strip-shaped undulating region can be different. The range of the height difference S1 between any group of adjacent protrusions 53 and recesses 54 in the entire encapsulating film is 5μm-15μm. When measuring the range of S1, one or more strip-shaped undulating regions can be selected for measurement.

[0030] On the same fine grid 12, the height difference S2 between a set of adjacent first peaks 121 and first valleys 122 at different locations can be different. 5μm-15μm is the range of the height difference S2 between any set of adjacent first peaks 121 and first valleys 122 throughout the entire fine grid 12. When measuring the range of S2 for a single fine grid 12, multiple sets of first peaks and valleys can be measured on the fine grid 12 to measure their height differences.

[0031] In related technologies, the fine grid is made of silver. The surface of the silver fine grid is relatively flat, and its height is small, typically 15μm±5μm. The surface of the silver fine grid is flat due to the screen printing of the paste, and it does not have a peak-valley structure with large differences. In this embodiment, the height difference S2 of a set of adjacent first peaks 121 and first valleys 122 is 5μm-15μm. This height difference gives the first valley 122 a certain depth, so that the encapsulating film can easily flow into the first valley 122 during lamination, covering the bottom of the first valley 122 and preventing the bottom of the first valley 122 from contacting oxygen.

[0032] In some embodiments, the difference between S2 and S1 is no greater than 0.3S2.

[0033] When S2 is between 5μm and 15μm, 0.3S2 corresponds to 1.5μm to 4.5μm. The difference between S2 and S1 is within a certain range. For a single fine grid 12, when measuring the range of the difference between S2 and S1, multiple sets of protrusions 53 and depressions 54 and their corresponding first peaks and valleys can be taken, and the difference between S2 and S1 for each set can be measured. When measuring the difference between S2 and S1 for each set, the height difference S2 of a set of adjacent first peaks 121 and first valleys 122 can be measured first, and then the height difference S1 of a set of adjacent protrusions 53 and depressions 54 corresponding to the adjacent first peaks 121 and first valleys 122 can be measured, and then the difference can be calculated.

[0034] When the difference between S2 and S1 is large, the protrusion 53 is embedded relatively shallowly into the first trough 122. There are likely to be many air bubbles and uncontacted portions between the protrusion 53 and the first valley bottom G of the first trough 122. When moisture intrudes, the fine grid 12 is prone to oxidation at this location. In this embodiment, the difference between S2 and S1 is no greater than 0.3S2, so the protrusion 53 is embedded deeper into the first trough 122. There are essentially no gaps or only a few gaps between the protrusion 53 and the first valley bottom G of the first trough 122, which can greatly reduce the risk of oxidation of the fine grid 12. Furthermore, when the difference between S2 and S1 is within the above range, the interdigitated structure can be considered to be well-bonded, with a low risk of pull-out separation, further reducing the risk of moisture intrusion.

[0035] In some embodiments, the encapsulating film is embedded in the first trough 122 to a depth of more than 2 / 3, and the above-described S2 can be used as the depth of the first trough 122. Alternatively, refer to... Figure 5 and Figure 6 The encapsulating film can at least partially contact the first valley bottom G of the first trough 122. In this part of the encapsulating film, S2 equals S1. In this embodiment, from the perspective of the first trough 122, at least the upper 2 / 3 of the first trough 122 is covered by the encapsulating film. At this time, even if the bottom of the first trough 122 is not completely filled by the encapsulating film, since the upper 2 / 3 of the first trough 122 is covered, moisture not only has difficulty eroding the upper part of the first trough 122, but also has difficulty penetrating the encapsulating film filling the opening of the first trough 122 to erode the bottom of the first trough 122.

[0036] In some embodiments, refer to Figure 6 The height H1 of the first peak 121 is between 10μm and 30μm. This height provides sufficient space for the film to be embedded in the interdigitated structure. Within this height range, the first peak 121 has no protrusions exceeding 5μm, thereby avoiding the aggravation of water vapor erosion caused by various protrusions on the first peak 121 piercing the insulating materials such as the encapsulation film.

[0037] Reference Figure 6The heights H1 of the various first peaks 121 are not exactly the same. The height range of any first peak 121 in the entire fine grid 12 is 10μm-30μm, preferably 15μm-30μm. When measuring the height range of the first peaks 121 in the entire fine grid 12, one first peak 121 can be randomly selected on a single fine grid 12, and its dimension in the thickness direction of the solar cell 10 can be measured to obtain the height of the first peak 121.

[0038] In some embodiments, along a first direction, the fine grid 12 includes two end segments and a middle segment located between the two end segments; in the end segments, the height difference between a set of adjacent protrusions 53 and recesses 54 is a first height difference, and in the middle segment, the height difference between another set of adjacent protrusions 53 and recesses 54 is a second height difference, wherein the first height difference is greater than the second height difference.

[0039] A larger height difference can be created between the first peak 121 and the first trough 122 of the end section, thereby indirectly controlling a greater height difference between the protrusion 53 and the recess 54 of the end section. Alternatively, the encapsulating film can be controlled to have a higher filling ratio than the middle section, thus achieving a greater height difference. The encapsulating film has a first surface that bonds to the battery cell 10 and a second surface opposite to the first surface. The height of the bottom of the recess 54 can refer to the distance between the bottom of the recess 54 and the second surface along the thickness direction of the battery cell 10.

[0040] In the end section, the height difference between a set of adjacent first peaks 121 and first troughs 122 is the third height difference. In the middle section, the height difference between another set of adjacent first peaks 121 and first troughs 122 is the fourth height difference. The third height difference is greater than the fourth height difference. The height of the first peak 121 in the end section can be greater than the height of the first peak 121 in the middle section, thus making the third height difference greater than the fourth height difference. Alternatively, the height of the first trough G in the end section can be less than the height of the first trough G in the middle section, thus making the third height difference greater than the fourth height difference.

[0041] The length of the end segment can be 1mm-5mm, for example, 1mm, 2.1mm, 3.1mm, 4.1mm, 5mm, etc. The difference between the first height difference and the second height difference can be 1μm-5μm, for example, the second height difference is 5μm-10μm, and the first height difference is 6μm-15μm. When measuring the range of the first height difference, the heights of adjacent protrusions 53 and recesses 54 on the end segment can be measured and the height difference calculated. The measurement of the second height difference is similar to the measurement of the first height difference.

[0042] At the end of the fine gate 12, oxidation caused by moisture intrusion is more likely to occur than in the middle of the fine gate 12. In this embodiment, the first height difference of the end section is greater than the second height difference of the middle section. The end section has a more obvious peak-valley height difference, which can form a stronger gripping force on the encapsulating film embedded therein, improve the bonding performance between the end section of the fine gate 12 and the encapsulating film, and thus reduce the probability of moisture intrusion from the end section of the fine gate 12.

[0043] In some embodiments, along the first direction, the distance D1 between adjacent first peaks 121 is 5μm-50μm, preferably 10μm-50μm, for example, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 50μm, etc.

[0044] When measuring D1, the distance between the first peak F of the first peak 121 with the relatively smaller height among two adjacent first peaks 121 along the first direction is defined as D1. The distance D1 characterizes the opening size of the first valley F between the two first peaks 121. When D1 is small, the opening of the first valley F between the two first peaks 121 is small, making it difficult for the viscous encapsulating film to flow into the first valley 122 during lamination. In this embodiment, D1 is greater than or equal to 5 μm, making it easier for the encapsulating film to flow into the first valley 122 during lamination to cover the bottom of the first valley 122. When D1 is greater than 50 μm, the distance between the two first peaks 121 is too large, which can easily weaken the interdigital bonding performance between the encapsulating film and the fine gate 12.

[0045] In some embodiments, along the first direction, the distance between adjacent first valleys G is 5μm-50μm, preferably 10μm-50μm. The distance between two adjacent first valleys G is also the dimension of the first peak 121 in this direction. When the dimension of the first peak 121 in this direction is less than 5μm, the first peak 121 has a thin and tall structure, which is relatively sharp and prone to protrusions. When the dimension of the first peak 121 in this direction is greater than or equal to 5μm, the bottom of the first peak 121 is wider, and with the adjustment of the paste of the fine grid 12, the first peak 121 can be made into a smooth convex part. When the distance between the first valleys G is greater than 50μm, the dimensions of the first peak 121 and the first valley 122 in the first direction are large and the density is low, which will reduce the bonding performance with the encapsulating film.

[0046] In some embodiments, the angle between the fine grid 12 and the surface of the battery body 11 is greater than 90°, and the fine grid 12 has two sidewalls opposite each other along a second direction, the height of the sidewalls not covered by the encapsulating film not exceeding 5 μm. Specifically, the angle between the fine grid 12 and the surface of the battery body 11 refers to the angle between the sidewall of the fine grid 12 and the surface of the battery body 11. The sidewall of the fine grid 12 is inclined relative to the thickness direction of the battery cell 10, or the sidewall of the fine grid 12 is arc-shaped. This angle is the outer angle between the fine grid 12 and the battery body 11, not the inner angle of the fine grid 12. This angle position is used to accommodate the encapsulating film. During lamination, the fluid encapsulating film flows and covers the surfaces of the battery body 11 and the fine grid 12.

[0047] In this embodiment, the angle between the fine grid 12 and the surface of the battery body 11 is relatively large. This facilitates the flow and coverage of the encapsulating film between the battery body 11 and the fine grid 12, especially at the angled position, forming an interlocking structure. This further enhances the bonding performance between the encapsulating film and the battery cell 10, preventing moisture from seeping in through the gaps between the battery body 11, the fine grid 12, and the encapsulating film, thus reducing the moisture penetration rate. At a larger angle, the height of the fine grid sidewall not covered by the encapsulating film is relatively small, for example, not exceeding 5 μm. This ensures that the encapsulating film has a large coverage of the fine grid sidewall, reducing the risk of exposure.

[0048] In some embodiments, the encapsulating film includes a first outer layer, an intermediate layer, and a second outer layer. The first outer layer can be made of EVA, the intermediate layer can be made of POE, and the second outer layer can be made of EVA.

[0049] The first outer layer is bonded to the fine gate 12, and the thickness of the first outer layer is 30μm-200μm. The thickness of the first outer layer can be 30μm, 50μm, 100μm, 150μm, 180μm, 200μm, etc. The overall thickness of the encapsulating film can be 300μm-500μm. Preferably, the thickness of the first outer layer is greater than twice the maximum height of the first peak 121, which is also the height of the highest first peak 121 within a certain range.

[0050] Along the thickness direction of the battery cell 10, the fine grid 12 does not penetrate the intermediate layer, or there is a distance D2 between the intermediate layer and the first peak 121 of the fine grid 12. POE, as the intermediate layer, has better moisture barrier and electrical insulation properties compared to EVA. The integrity of the POE layer has a significant impact on preventing moisture penetration. If the POE layer is damaged, its performance in preventing moisture penetration will decrease. In this embodiment, the fine grid 12 does not penetrate the intermediate layer, thus ensuring the integrity of the intermediate layer. When there is a gap between the intermediate layer and the first peak 121 of the fine grid 12, the intermediate layer will not contact the first peak 121, better preventing the protruding part on the first peak 121 from piercing the intermediate layer, thereby ensuring the performance in preventing moisture penetration.

[0051] In some embodiments, D2 is greater than or equal to the maximum height of the first peak 121. In this embodiment, D2 is relatively large, so even if there is an error in the thickness of the first outer layer, the intermediate layer is less likely to come into contact with the first peak 121, thereby further optimizing the protection of the fine gate 12 by the encapsulating film. In production, the size of D2 can be adjusted by adjusting the thickness of the first outer layer and the height of the first peak 121 of the fine gate 12.

[0052] In some embodiments, refer to Figure 10 The battery body 11 has a passivation layer 111 on both the front and back sides. The passivation layer 111 can be a single layer or a double layer, and the material of the passivation layer 111 can include aluminum oxide or silicon nitride or a combination of both. The battery body 11 can be a BC battery or a TOPcon battery.

[0053] At least one side of the encapsulating film of the solar cell 10 is made of EPE. The EPE encapsulating film includes a first outer layer, an intermediate layer, and a second outer layer. The first outer layer is made of EVA, the intermediate layer is made of POE, and the second outer layer is made of EVA. The passivation layer 111 provides a certain degree of waterproof protection. When the EPE encapsulating film and the passivation layer 111 are combined, the passivation layer 111 and the EPE stack can provide good waterproof protection for the non-fine grid parts on the solar cell body 11, reducing the risk of water vapor and EVA forming acetate ions that carry base metals such as copper into the cell. The EPE provides waterproof protection for the electrode parts such as the fine grid 12 on the solar cell body 11, thus providing complete waterproof protection for the entire surface of the solar cell 10. This extends the lifespan of the solar cell 10 in the module.

[0054] In some embodiments, refer to Figure 2 , Figure 3 and Figure 9The battery cell 10 also includes a connection portion 13 electrically connected to the fine grid 12. Interconnectors are electrically connected to the connection portions 13 of adjacent battery cells 10. The connection portion 13 is electrically connected to the interconnector via a conductive layer 20. The connection portion 13 is soldered to the interconnector via the conductive layer 20, and the soldering method can be infrared soldering. The conductive layer 20 can be conductive adhesive or solder paste, and the conductive layer 20 can be formed on the connection portion 13 by printing.

[0055] Reference Figure 9 The connecting portion 13 has a second peak 131 and a second valley 132 that undulate in the thickness direction; one second valley 132 is filled with a conductive layer 20, and the ratio of the filling depth of the conductive layer 20 in the second valley 132 to the depth of the second valley 132 is N1; the other second valley 132 is filled with an encapsulating film, and the ratio of the filling depth of the encapsulating film in the second valley 132 to the depth of the second valley 132 is N2, where N2 > N1.

[0056] The second peak 131 is the portion of the connecting portion 13 that protrudes away from the battery body 11 relative to the surrounding area, and the second trough 132 is the portion of the connecting portion 13 that is recessed relative to the second peak 131. The entire surface of the connecting portion 13 has a second peak 131 and a second trough 132 that undulate in the thickness direction. Some of the second peaks 131 and second troughs 132 can be arranged along the second direction, and some of the second peaks 131 and second troughs 132 can also be arranged along other directions intersecting the second direction. In the connection between the interconnect and the battery cell 10, the connection between the connecting portion 13 and the conductive layer 20 is a critical risk point, which is prone to problems such as poor soldering, leading to interconnect connection failure. In this embodiment, the connecting portion 13 has a second peak 131 and a second trough 132, and the conductive layer 20 is embedded in the second trough 132, which can increase the bonding area between the two, improve the bonding performance between the connecting portion 13 and the conductive layer 20, and thus improve the pull-out force between the interconnect and the battery cell 10.

[0057] It should be understood that on the surface of the connector 13, part of it is connected to the interconnect via the conductive layer 20, while the remaining exposed portion is covered by an encapsulating film. The portion covered by the conductive layer 20 can form a better cover during the welding process, thus blocking moisture. The exposed portion is also protected from moisture by the encapsulating film. Compared to dense alloy welding, the exposed portion of the connector 13 is at greater risk of moisture erosion. For the second peak 131 and second trough 132 on the connector 13, when the embedding degree (interdigitation) of the encapsulating film is greater than the filling degree of the conductive layer 20, the encapsulating film can improve the protection of the exposed portion of the connector 13 through greater coverage and deeper interdigitation.

[0058] In some embodiments, the material of the connecting portion 13 is the same as the material of the fine grid 12.

[0059] The connecting part 13 can be printed integrally with the fine grid 12, or it can be printed separately. In the latter case, the connecting part 13 is printed after the fine grid 12 is printed. For separate printing, refer to... Figure 3 The fine grid 12 and the connecting part 13 can have a certain overlap length.

[0060] In some embodiments, refer to Figure 9 The arrangement direction of some of the second peaks 131 and second troughs 132 intersects with the arrangement direction of the first peaks 121 and first troughs 122. Along the first direction, in the edge region of the connecting portion 13, the connecting portion 13 overlaps with the fine grid 12, and the first peak 121 and the second peak 131 intersect and overlap. The dimension of the edge region of the connecting portion 13 along the first direction is equal to the overlap length between the fine grid 12 and the connecting portion 13. By combining the peaks and troughs in two arrangement directions, it is possible to prevent solder paste from overflowing the pads during printing, thereby preventing short circuits and contamination of the battery cell 10 caused by solder paste overflow.

[0061] In some embodiments, the battery cell 10 further includes a connection portion 13 electrically connected to the fine grid 12, the connection portion 13 being electrically connected to an interconnecting member; the interconnecting member includes a substrate and a welding layer disposed on the outer periphery of the substrate.

[0062] The connecting portion 13 has a second peak 131 and a second valley 132 undulating in the thickness direction, and the welding layer is embedded in the second valley 132. One second valley 132 is filled with the welding layer, and the ratio of the filling depth of the welding layer in the second valley 132 to the depth of the second valley 132 is N3. The other second valley 132 is filled with an encapsulating film, and the ratio of the filling depth of the encapsulating film in the second valley 132 to the depth of the second valley 132 is N4, where N4 > N3.

[0063] The base material can be copper, and the solder layer material includes tin with a mass percentage of 50% or more. For example, the solder layer material is a tin alloy, such as a tin-lead alloy. The interconnects can be flat solder strips, round solder strips, triangular solder strips, solder strips with an elliptical or other polygonal cross-section, etc.

[0064] In this embodiment, the connecting portion 13 has a second peak 131 and a second valley 132. The welding layer is embedded in the second valley 132, which can improve the welding performance of the connecting portion 13 and the interconnect, increase the welding pull force, and thus increase the pull-out force between the interconnect and the battery cell 10.

[0065] This embodiment primarily addresses the case where the solder strip and the connector 13 are in direct contact. On the connector 13, a large portion is covered by the solder layer of the solder strip, achieving good water resistance through dense welding. The unwelded portions of the connector 13 achieve water resistance by forming an interdigitated structure with the encapsulating film. The adhesive bond between the encapsulating film and the connector 13 is slightly weaker than welding. However, when the encapsulating film is more deeply embedded than the solder layer, the bonding strength between the encapsulating film and the connector 13 can be further increased, thus enhancing the water-resistant effect.

[0066] In some embodiments, along the second direction, the battery cell 10 has a busbar, the extension direction of which intersects the first direction; the busbar is electrically connected to and intersects with the same polarity fine grid 12; the busbar has a third peak and a third trough undulating in the thickness direction, and the arrangement direction of the third peak and the third trough is the same as the extension direction of the busbar; a portion of the encapsulating film is embedded in the third trough, and the encapsulating film and the busbar form an interdigitated structure.

[0067] The third peak is the portion that protrudes away from the battery body 11 relative to the surrounding area, and the third trough is the portion that is recessed towards the battery body 11 relative to the third peak. The extension direction of the busbar can be a second direction. In this embodiment, the arrangement direction of the third peak and the third trough of the busbar intersects with the arrangement direction of the first peak 121 and the first trough 122 on the fine grid 12. The peak-valley structure arranged in two directions facilitates the overlapping of the first peak 121 and the third peak to form a grid structure, which can improve the adhesion of the fine grid 12 to the encapsulating film. When part of the encapsulating film is embedded in the third trough, and the encapsulating film forms an interdigitated structure with the busbar, the encapsulating film, the fine grid 12, and the busbar form a grid-arranged, intersecting interdigitated structure, which can further improve the encapsulation and waterproofing of the busbar surface by the encapsulating film.

[0068] Reference Figure 2 and Figure 3 Along the second direction, the solar cell 10 has an edge region with an end line 14 for collecting current in the edge region. The busbar can be the end line 14. Along the second direction, the solar cell 10 has two opposing first edges. A connecting portion includes an edge connecting portion near the first edge of the solar cell 10, and an intermediate connecting portion located between the two edge connecting portions. The dimension of the edge connecting portion along the second direction is larger than the dimension of the intermediate connecting portion along the second direction. The edge region can be the region between the edge connecting portion and the first edge.

[0069] In this embodiment, the busbar, which serves as the end line 14, is mainly located in the edge area of ​​the battery cell 10, making it more susceptible to moisture erosion. At this time, the interdigitated structure formed between the encapsulation film and the end line 14 can provide better moisture protection.

[0070] In other embodiments, the bus line may also be a main gate extending along the second direction.

[0071] In some embodiments, there are no air bubbles larger than 5 μm between the surface of the first peak 121 and / or the first trough 122 and the encapsulating film. Preferably, there are no air bubbles larger than 3 μm. In this embodiment, there are no large air bubbles, or even no air bubbles, between the surface of the first peak 121 and / or the first trough 122 and the encapsulating film, and the encapsulating film is tightly bonded to the undulating structure of the fine grid 12, resulting in good water vapor intrusion resistance.

[0072] In some embodiments, refer to Figure 2 and Figure 3 The solar cell 10 is a back-contact solar cell, and the fine grid 12 is disposed on the back side of the solar cell body 11. The photovoltaic module also includes an insulating member 30, which is disposed on the fine grid 12. The top surface of the insulating member 30 away from the fine grid 12 can be an arc surface, and along the second direction, the middle part of the arc surface is higher than the two ends of the arc surface. The fine grid 12 is usually located below the middle part of the insulating member 30. In this embodiment, the middle part of the arc surface of the insulating member 30 is higher than the two ends of the top surface, that is, the middle part of the insulating member 30 is relatively high, which can effectively prevent the crests in the fine grid 12 from piercing the insulating member 30. The thickness of the insulating member 30 can be 20μm-45μm, and the thickness of the insulating member 30 is preferably greater than the maximum height of the first crest 121 to prevent the crests in the fine grid 12 from piercing the insulating member 30.

[0073] A portion of the first trough 122 of the fine grid 12 is filled with an encapsulating film, and another portion of the first trough 122 is filled with an insulating member 30. The insulating member 30 is embedded in the first trough 122, increasing the bonding area between the insulating member 30 and the fine grid 12, thereby improving the bonding performance between the insulating member 30 and the fine grid 12. A continuous path for water vapor intrusion is formed along the length of the fine grid 12; and the continuous distribution of the encapsulating film on the fine grid 12 and the insulating member 30 avoids localized exposure of the fine grid 12, reducing the probability of water vapor penetrating through the gap between the encapsulating film and the insulating member 30.

[0074] The material and molding process of the insulating element 30 do not need to be changed. The insulating element 30 can be an insulating adhesive. The insulating element 30 can be formed by printing insulating material on the fine grid 12 and curing it.

[0075] In some embodiments, the difference between the filling depth ratio of the encapsulating film and the filling depth ratio of the insulating element 30 on a fine grid 12 is less than or equal to 0.1. The filling depth ratio can be calculated as the proportion or percentage of the filling depth of the first trough 122 on the fine grid 12 to the total depth of the first trough 122. When the difference is less than or equal to 0.1, it indicates that the filling degree of the encapsulating film and the insulating element 30 is not significantly different, thereby reducing weak areas in moisture protection.

[0076] In some embodiments, the tops of the insulating element 30, the connecting portion 13, and the interconnecting element are covered with an encapsulating film. The encapsulating film can be partially embedded in the recesses of the insulating element 30. The encapsulating film can also be partially embedded in the recesses of the conductive layer 20 on the connecting portion 13. The encapsulating film can also be partially embedded in the recesses of the welding layer on the connecting portion 13. In this case, the encapsulating film can fill the recesses on the surface of the insulating element 30, avoiding problems such as leakage and moisture penetration caused by the thinness of the insulating element 30 at the recesses. When the encapsulating film is embedded in the recesses on the surfaces of the insulating element 30, the conductive layer 20, and the welding layer, under the pressure of the lamination process, the battery cell 10, the insulating element 30, the connecting portion 13, the welding layer, and the encapsulating film can be pressed together more tightly. Compared with planar contact, the interlocking contact and pressing has better bonding performance.

[0077] In some embodiments, along the thickness direction of the battery cell 10, there is a gap or bubble with a height of less than or equal to 5 μm between the insulating member 30 and the first trough 122, and the height direction of the gap or bubble is consistent with the thickness direction of the battery cell 10.

[0078] After the insulating material is printed, there is a gap between the insulating component 30 and the first trough 122. During the curing process of the insulating material, this gap can absorb gas and facilitate the formation of bubbles, thereby reducing the bubble content in the central region of the insulating component 30. After the insulating material is cured, there is a gap or bubbles between the insulating component 30 and the first trough 122. In this embodiment, the bubble content in the central region of the insulating component 30 can be reduced, ensuring the insulation performance of the insulating component 30.

[0079] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0080] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other modifications under the guidance of the present invention without departing from the spirit and scope of the present invention, and all of these modifications are within the protection scope of the present invention.

Claims

1. A photovoltaic module, characterized in that, It includes multiple battery cells and an encapsulating film disposed on at least one side of the battery cells. The battery cells include a plurality of fine grids extending along a first direction and spaced apart along a second direction. The main conductive material of the fine grids includes copper, aluminum, nickel, iron, zinc, tin or tungsten. The fine grid is undulating in the thickness direction. The undulating fine grid has multiple first peaks and multiple first valleys arranged along the first direction. The encapsulating film combined with the fine grid has protrusions and depressions. The depressions are in contact with the first peaks, and the protrusions are embedded in the first valleys. The fine grid and the encapsulating film are interlocked to form an interdigitated structure.

2. The photovoltaic module according to claim 1, characterized in that, The encapsulating film has a height difference S1 between a group of adjacent protrusions and depressions, where S1 is between 5 μm and 15 μm.

3. The photovoltaic module according to claim 2, characterized in that, The first peak and the first trough corresponding to a set of adjacent protrusions and depressions have a height difference S2, and the difference between S2 and S1 is no greater than 0.3S2.

4. The photovoltaic module according to claim 1, characterized in that, The encapsulating film is embedded in the first trough to a depth of more than 2 / 3; or, the encapsulating film at least partially contacts the bottom of the first trough.

5. The photovoltaic module according to claim 1, characterized in that, Along the first direction, the fine grid includes two end segments and a middle segment located between the two end segments; In the end section, the height difference between a set of adjacent protrusions and recesses is a first height difference; in the middle section, the height difference between another set of adjacent protrusions and recesses is a second height difference, and the first height difference is greater than the second height difference.

6. The photovoltaic module according to claim 1, characterized in that, Along the first direction, the distance D1 between adjacent first peaks is between 5 μm and 50 μm.

7. The photovoltaic module according to claim 1, characterized in that, The battery cell also includes a battery body, and the fine grid is fixed on the battery body; the angle between the fine grid and the surface of the battery body is greater than 90°, and the fine grid has two sidewalls opposite each other along a second direction, and the height of the sidewalls not covered by the encapsulating film does not exceed 5 μm.

8. The photovoltaic module according to claim 1, characterized in that, The encapsulating film includes a first outer layer, an intermediate layer, and a second outer layer, wherein the first outer layer is bonded to the fine grid. Along the thickness direction of the solar cell, the fine grid does not penetrate the intermediate layer, or there is a distance D2 between the intermediate layer and the first peak of the fine grid.

9. The photovoltaic module according to claim 8, characterized in that, D2 is greater than or equal to the maximum height of the first peak.

10. The photovoltaic module according to claim 1, characterized in that, The battery cell also includes a battery body, and the front and back sides of the battery body have passivation layers. The encapsulation film on at least one side of the battery cell is EPE.

11. The photovoltaic module according to claim 1, characterized in that, The solar cell also includes a connection portion electrically connected to the fine grid, and the photovoltaic module also includes an interconnection member, which is electrically connected to the connection portion of adjacent solar cells. The connection portion is electrically connected to the interconnection member through a conductive layer. The connection portion has a second peak and a second trough undulating in the thickness direction. The second valley is filled with the conductive layer, and the ratio of the filling depth of the conductive layer in the second valley to the depth of the second valley is N1; Another second trough is filled with the encapsulating film, and the ratio of the filling depth of the encapsulating film in the second trough to the depth of the second trough is N2, where N2 > N1.

12. The photovoltaic module according to claim 11, characterized in that, The arrangement directions of some of the second peaks and second troughs intersect with the arrangement directions of the first peaks and first troughs; along the first direction, in the edge region of the connecting portion, the first peaks and second peaks overlap.

13. The photovoltaic module according to claim 1, characterized in that, The solar cell further includes a connection portion electrically connected to the fine grid, and the photovoltaic module further includes an interconnect, the connection portion being electrically connected to the interconnect; the interconnect includes a substrate and a welding layer disposed on the outer periphery of the substrate; the connection portion has a second peak and a second trough undulating in the thickness direction; The second trough is filled with the weld layer, and the ratio of the filling depth of the weld layer in the second trough to the depth of the second trough is N3; Another second trough is filled with the encapsulating film, and the ratio of the filling depth of the encapsulating film in the second trough to the depth of the second trough is N4, where N4 > N3.

14. The photovoltaic module according to claim 1, characterized in that, Along the second direction, the battery cell has a busbar, the extension direction of which intersects the first direction; the busbar is electrically connected to and intersects with the fine grid of the same polarity; The busbar has a third peak and a third trough undulating in the thickness direction, and the arrangement direction of the third peak and the third trough is the same as the extension direction of the busbar; part of the encapsulating film is embedded in the third trough, and the encapsulating film and the busbar form an interdigitated structure.

15. The photovoltaic module according to claim 1, characterized in that, The photovoltaic module also includes an insulating component, which is disposed on the fine grid. A portion of the first trough of the fine grid is filled by the encapsulating film, and a portion of the first trough is filled by the insulating element.

16. The photovoltaic module according to claim 15, characterized in that, On the fine grid, the difference between the filling depth ratio of the encapsulating film and the filling depth ratio of the insulating element is less than or equal to 0.

1.

17. The photovoltaic module according to claim 12, 13, or 16, characterized in that, The top of the insulating parts, connecting parts and interconnecting parts is covered with the encapsulating film; The encapsulating film is partially embedded in the recess of the insulating component, or the encapsulating film is partially embedded in the recess of the conductive layer surface on the connector, or the encapsulating film is partially embedded in the recess of the welding layer surface on the connector.

18. A photovoltaic system, characterized in that, Including the photovoltaic module as described in any one of claims 1 to 17.

Images