Photovoltaic module and photovoltaic system

Abstract

The invention provides a photovoltaic module and a photovoltaic system, and relates to the technical field of photovoltaics. The photovoltaic module comprises a battery piece; the battery piece is provided with an electrode; the electric connecting piece is provided with a metal inner core; the metal inner core is electrically connected with electrodes of two adjacent battery pieces through a bonding material; a first alloy layer is formed between the bonding material and the metal inner core; the section perpendicular to the length extending direction of the metal inner core is a first section, and in the first section, the first alloy layer wraps over 80% of the contour line of the metal inner core. According to the photovoltaic module, the connection quality is reliable, the current transmission effect is good, excessive connection basically does not exist, and the connection reliability and stability of the photovoltaic module in the service period for many years can be improved.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a photovoltaic component and a photovoltaic system. Background Art

[0002] The process of forming a photovoltaic module includes connecting two adjacent cells in series using electrical connectors. The quality of the series connection process is directly related to the reliability of the photovoltaic module. If the connection is unstable, the cell string will be disconnected, exposed, short-circuited, etc., which will seriously affect the power and product performance of the photovoltaic module.

[0003] In existing photovoltaic modules, the connection reliability is poor, which causes the electrical connectors to easily detach from the solar cells during the years of service, affecting the quality and reliability of the photovoltaic modules. Summary of the invention

[0004] The present invention provides a photovoltaic assembly and a photovoltaic system, aiming to solve the problem of poor connection reliability in existing photovoltaic assemblies.

[0005] A first aspect of the present invention provides a photovoltaic module, comprising:

[0006] A battery cell; the battery cell is provided with electrodes;

[0007] An electrical connector having a metal inner core;

[0008] The metal inner core is electrically connected to electrodes of two adjacent battery cells through a bonding material; a first alloy layer is formed between the bonding material and the metal inner core;

[0009] A cross section perpendicular to the length extension direction of the metal inner core is a first cross section, and in the first cross section, the first alloy layer covers more than 80% of the contour line of the metal inner core.

[0010] In the first cross section, the first alloy layer covers more of the contour line of the metal core, and the first alloy layer covers most of the contour line of the metal core. The first alloy layer formed between the bonding material and the metal core covers the metal core more completely. On the one hand, covering the metal core to a greater extent can ensure that the connection reliability between the metal core and the bonding material is high, and reduce the metal core from coming out of the bonding material due to tension and other reasons. On the other hand, it can ensure that most of the surface of the metal core is covered by the first alloy layer in a non-exposed state, thereby reducing the risk of the metal core being corroded and oxidized by water vapor during the long-term service of the photovoltaic module due to the exposure of the metal core, and further ensure that the conductive properties and physical and chemical properties of the metal core are stable. Therefore, when the first alloy layer covers more of the metal core, that is, covers more than 80%, the photovoltaic module has better electrical connection reliability, conductive properties, and structural stability.

[0011] A second aspect of the present invention provides a photovoltaic system, comprising: a plurality of any of the aforementioned photovoltaic components distributed in an array.

[0012] The above-mentioned photovoltaic modules and photovoltaic systems have the same or similar beneficial effects, which will not be described again here to avoid repetition. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0014] Figure 1 A front view structural schematic diagram of a photovoltaic assembly in an embodiment of the present invention is shown;

[0015] Figure 2 A first partial SEM schematic diagram of a photovoltaic module in an embodiment of the present invention is shown;

[0016] Figure 3 A second partial SEM schematic diagram of a photovoltaic module in an embodiment of the present invention is shown;

[0017] Figure 4 A schematic diagram showing the distribution structure of an electrical connector and a bonding material in an embodiment of the present invention is shown;

[0018] Figure 5 A third partial SEM schematic diagram of a photovoltaic module in an embodiment of the present invention is shown;

[0019] Figure 6 A schematic diagram showing the connection between an electrical connector and a battery cell in an embodiment of the present invention is shown;

[0020] Figure 7 A schematic structural diagram of a second alloy layer in another photovoltaic module in an embodiment of the present invention is shown.

[0021] Description of the accompanying drawings:

[0022] 1-battery cell, 11-electrode, 111-connecting part, 2-electrical connecting piece, 21-metal inner core, 22-bonding material, 221-first bonding material, 222-second bonding material, 31-first alloy layer, 32-second alloy layer, 321-second alloy point. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In the related art, for the electrical connection in the photovoltaic module, the main focus is only on whether an alloy is formed between the electrode and the electrical connector. However, the formation of an alloy between the metal core of the electrical connector and the bonding material is extremely important for the connection reliability and stability of the photovoltaic module. In the photovoltaic module of the present application, a first alloy layer is formed between the metal core of the electrical connector and the bonding material. The first alloy layer exists as an electrical and mechanical connector between the metal core and the bonding material, which can improve the current collection effect and enhance the connection reliability and stability of the photovoltaic module during many years of service.

[0025] In addition, in the related art, for the electrical connections in photovoltaic modules, the main focus is on the tension value. It is believed that the larger the tension value, the better the electrical connection quality. However, sometimes, although the tension value of the connection meets the requirements, there may still be phenomena such as over-connection or virtual connection that affect the connection quality. In this application, the electrical connection quality of photovoltaic modules is studied from a more subtle and comprehensive perspective, so as to ensure a suitable, reliable and fixed connection effect.

[0026] The present invention provides a photovoltaic module, referring to Figure 1 The photovoltaic module comprises: a cell 1 and an electrical connector 2. The cell 1 is provided with an electrode 11, and the electrode 11 is used to collect and conduct current. The electrical connector 2 has a metal inner core 21, and the metal inner core 21 electrically connects the electrodes 11 of two adjacent cells 1 through a bonding material 22.

[0027] The bonding material 22 may be a bonding material attached to the electrical connector 2, or may be a bonding material independently provided from the electrical connector 2, for example, the bonding material 22 may be a separately provided solder paste, tin alloy material, etc. This is not specifically limited. Figure 1 In the embodiment, the bonding material 22 may be a bonding material attached to the electrical connector 2. The bonding material 22 may also be a combination of a bonding material attached to the electrical connector 2 and a bonding material such as solder paste that is independently provided.

[0028] It should be noted that the main component of the bonding material includes tin. On the one hand, tin has a low melting point, the energy consumption of the interconnection process is low, and the connection process is simple. Moreover, tin has good fluidity in a molten state and can easily form a good coating or covering with the metal core of common electrical connectors such as a copper core.

[0029] A first alloy layer 31 is formed between the bonding material 22 and the metal core 21. The first alloy layer 31 may be an intermetallic compound (IMC). The first alloy layer 31 acts as an electrical and mechanical connector between the bonding material 22 and the metal core. A second alloy layer is formed between the bonding material and the electrode. It should be noted that the process of electrically connecting the electrodes of two adjacent battery cells using the electrical connector 2 mainly includes processes such as surface wetting, interatomic diffusion, dissolution, and metallurgical bonding. This is a very complex chemical reaction. Whether a good IMC can be formed is a key indicator of the connection quality. Figure 6 The electrical connector 2 is specifically used to electrically connect the positive electrode of one battery cell with the negative electrode of another battery cell in two adjacent battery cells to achieve interconnection.

[0030] It should be noted that the first alloy layer and the second alloy layer described below may be two substances that form a relatively stable chemical bond so as to exist as an electrical and mechanical connector to conduct and transmit current.

[0031] This application mainly solves the connection reliability problem of photovoltaic modules from the following four levels. The first level is mainly to improve and ensure the connection reliability of photovoltaic modules by improving the various characteristics of the first alloy layer. The second level is mainly to improve the second alloy layer 32 formed between the electrode 11 and the bonding material 22 to improve the connection reliability of photovoltaic modules. The third level is mainly to improve the various characteristics at a connection point between the electrical connector 2 and the electrode 11 to improve the connection reliability of photovoltaic modules. The fourth level is mainly to control the morphological characteristics of the electrical connector 2 and the electrode 11 to improve the connection reliability of photovoltaic modules. Through the research on the above four levels, this application has significantly improved the connection reliability in photovoltaic modules, reduced the risk of electrical connectors detaching from the battery cells during the service of photovoltaic modules for many years, and improved the quality and reliability of photovoltaic modules. It should be understood that the improvements in the above four aspects can be achieved by using any one of the schemes to improve the connection reliability of the electrical connector and the battery cell, and of course, multiple schemes can be superimposed to achieve better results. Starting from the first level, the improvements of photovoltaic modules from the first level to the fourth level are introduced one by one.

[0032] The following is a detailed introduction to the main contents of the first level. Figure 2 , Figure 3 All of them are local SEM (scanning electron microscope) images of the first cross section of the photovoltaic module. The first cross section is a cross section perpendicular to the extension direction of the length of the metal inner core 21 in the photovoltaic module. Figure 1In the figure, the direction perpendicular to the paper plane is the length extension direction of the metal core 21 or the extension direction of the metal core 21. In the first cross section, the first alloy layer 31 covers more than 80% of the contour line of the metal core 21. That is to say, in the first cross section, the first alloy layer 31 covers most of the contour line of the metal core 21, and the first alloy layer formed between the bonding material 22 and the metal core 21 covers the metal core 21 more completely. On the one hand, a greater degree of coating of the metal core can ensure a high connection reliability between the metal core 21 and the bonding material 22, and reduce the metal core from escaping from the bonding material due to tension and other reasons. On the other hand, it can ensure that most of the surface of the metal core is covered by the first alloy layer in a non-exposed state, thereby reducing the risk of the metal core 21 being exposed and corroded and oxidized by water vapor during the long-term service of the photovoltaic module, thereby ensuring the stability of the conductive properties and physical and chemical properties of the metal core. Therefore, when the first alloy layer covers more of the metal core, that is, more than 80%, the electrical connection reliability, electrical conductivity and structural stability of the photovoltaic module are better.

[0033] For example, in the first cross section, the first alloy layer 31 may cover 80%, 83%, 85%, 89%, 90%, 92%, 95%, 96%, 98.3%, 99%, 99.2%, 99.7%, or 100% of the contour line of the metal core 21 .

[0034] In some embodiments, in the first cross-section, the first alloy layer 31 covers more than 90% of the contour line of the metal core 21. Here, it mainly means that the first alloy layer 31 covers more of the contour line of the metal core 21, and the first alloy layer formed between the bonding material 22 and the metal core 21 covers the metal core 21 more completely. The connection reliability between the metal core 21 and the bonding material 22 is higher, and the risk of exposure of the metal core 21 can be further reduced, thereby improving the electrical connection reliability, conductivity, and structural stability of the photovoltaic module.

[0035] For example, in the first cross section, the first alloy layer 31 may cover 90%, 91%, 93%, 94%, 95.3%, 96.7%, 98.2%, 97.5%, 99.1%, 99.5%, 99.6%, 99.4%, or 100% of the contour line of the metal core 21.

[0036] In some embodiments, in the first cross section, the first alloy layer 31 includes: an inner contour close to the metal inner core 21 and an outer contour away from the metal inner core 21, and the ratio of the length of the outer contour to the perimeter of the contour line of the metal inner core 21 is (0.8 to 5): 1. At this time, it can be ensured that both the inner and outer contours of the first alloy layer cover the metal inner core, that is, the first alloy layer covering the metal inner core has a sufficient thickness, which can achieve a better fixing and covering effect.

[0037] The perimeter of the outer contour of the first alloy layer 31 refers to the total length of the outer contour of the first alloy layer 31. For example, if the outer contour of the first alloy layer 31 is an arc or a circle, the length of the outer contour is the perimeter of the sector or the perimeter of the circle. For example, if the outer contour of the first alloy layer 31 is a circle and its radius is r, the length of the outer contour is 2πr. The perimeter of the contour of the metal inner core 21 refers to the total length of the contour of the metal inner core 21 in the first section. For example, if the metal inner core 21 is a circular metal inner core and its radius is x, the perimeter of its contour is 2πx. For another example, if the metal inner core 21 is a flat metal inner core, its contour line in the first cross section is a rectangle, the lengths of the two perpendicular sides of the rectangle are a and b respectively, a can be the width of the flat metal inner core, b can be the thickness of the flat metal inner core, the direction of the length of the flat metal inner core, the direction of the width of the flat metal inner core and the direction of the thickness of the flat metal inner core are perpendicular to each other, then the perimeter of its contour line is 2a+2b. When the outer contour of the first alloy layer is an irregular shape, its perimeter is the length of the irregular outer contour line.

[0038] For example, in the first cross section, the ratio of the length of the outer contour of the first alloy layer 31 to the circumference of the contour line of the metal core 21 can be 0.8:1, 0.85:1, 0.95:1, 0.97:1, 0.88:1, 0.95:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 2.7:1, 2.9:1, 3:1, 3.3:1, 3.5:1, 3.8:1, 4:1, 4.2:1, 4.5:1, 4.7:1, 5:1, etc.

[0039] In some embodiments, the thickness of the first alloy layer 31 is 0.5 μm to 4 μm, and the direction of the thickness of the first alloy layer 31 is from the outer contour to the inner contour of the first alloy layer 31. When the first alloy layer 31 is in this thickness range, the thickness of the first alloy layer covering the metal inner core is suitable, the first alloy layer has good mechanical connection strength and stable physical and chemical properties. More specifically, if the thickness of the first alloy layer 31 is less than 0.5 μm, no firm and reliable mechanical connection is formed between the metal inner core 21 and the bonding material 22. If the thickness of the first alloy layer 31 is greater than 4 μm, the first alloy layer 31 has a certain brittleness and is easy to break. It should be noted that for a metal inner core 21, the thickness of the first alloy layer 31 at different positions may not be exactly the same. The thickness of the first alloy layer here may refer to the maximum thickness in a certain area of ​​the first alloy layer 31.

[0040] For example, the thickness of the first alloy layer 31 may be 0.5 μm, 0.55 μm, 0.9 μm, 1 μm, 1.05 μm, 1.5 μm, 2 μm, 2.5 μm, 2.9 μm, 3 μm, 3.5 μm, 3.9 μm, or 4 μm.

[0041] In some embodiments, reference Figure 3 , the first alloy layer 31 surrounds the metal inner core 21 in a wavy shape. The main components of the first alloy layer include tin-copper intermetallic compounds. Specifically, the main components of the bonding material are metals such as tin, and the main metal components in the bonding material are unevenly distributed. The wavy shape makes it easier to form a continuous IMC, further ensuring that the metal inner core 21 is covered to the greatest extent, and further improving the connection reliability of the metal inner core. The main components of the first alloy layer are determined by the bonding material and the metal inner core. Different bonding materials combined with different metal cores can form first alloy layers of different materials. When the main components of the first alloy layer include tin-copper intermetallic compounds (such as Cu6Sn5), the material properties are relatively stable, and the materials are easy to combine with each other, so that the manufactured photovoltaic components have good electrical connection effects.

[0042] In some embodiments, reference Figure 3 In the first cross section, the first alloy layer 31 includes: an inner contour and an outer contour, and the inner contour and the outer contour refer to the above description. The metal inner core 21 is a circular metal inner core, and the ratio of the circumference of the contour line of the metal inner core to the length of the outer contour of the first alloy layer is 2πx: 2π(x+0.5) to 2πx: 2π(x+4); x is the radius of the metal inner core, in mm. In actual production, the generation of the first alloy layer, that is, the outer contour length of the first alloy layer, can be appropriately controlled according to the size of the circular metal inner core, so as to achieve better connection, fixation and covering effects.

[0043] For example, the metal inner core 21 is a circular metal inner core. When the radius x of the metal inner core is 1 mm, the ratio of the circumference of the contour line of the metal inner core 21 to the length of the outer contour of the first alloy layer 31 can be 4π:6π to 4π:10π.

[0044] The metal inner core 21 is a flat metal inner core, and the ratio of the circumference of the contour line of the metal inner core to the length of the outer contour of the first alloy layer is 2(a+b):2(a+0.5)(b+0.5) to 2(a+b):2(a+4)(b+4); a is the width of the metal inner core, b is the thickness of the metal inner core, and the units of a and b are both mm. In actual production, the generation of the first alloy layer, such as thickness, coverage, etc., can be controlled according to the width and thickness of the flat metal inner core, that is, the outer contour length of the first alloy layer, so as to achieve better connection, fixation and covering effects. Exemplarily, the cross-sectional shape of the flat metal inner core can be rectangular, square, elliptical, thick in the middle and thin on both sides, spindle-shaped, etc.

[0045] For example, the metal core 21 is a flat metal core. When the width a of the metal core is 2 mm and the thickness of the metal core is 4 mm, the ratio of the circumference of the contour line of the metal core 21 to the length of the outer contour of the first alloy layer 31 can be 12:22.5 to 12:96.

[0046] In some embodiments, the metal inner core 21 may be a triangular metal inner core, and the ratio of the perimeter of the contour line of the metal inner core 21 to the length of the outer contour of the first alloy layer 31 is (m+n+p): (m+n+p+1.5) to (m+n+p): (m+n+p+12); m, n, and p are the side lengths of the cross section of the metal inner core, respectively, and the units are all mm. The triangular metal inner core refers to a metal inner core having a triangular cross-sectional shape, such as an isosceles triangle, a non-isosceles triangle, and the like. Exemplarily, when the side m of the triangular metal inner core is 2 mm, n is 1.5 mm, and p is 1.5 mm, the ratio of the perimeter of the contour line of the metal inner core 21 to the length of the outer contour of the first alloy layer 31 may be 5:6.5 to 5:17. At this time, the coverage degree and the coverage thickness of the first alloy layer of the important connection layer can be adjusted according to the size of the metal inner core by adjusting the interconnection process.

[0047] In some embodiments, in the first cross section, the cross-sectional area of ​​the metal inner core 21 is greater than or equal to 0.00785 mm 2 The metal inner core 21 has a larger cross-sectional area and a smaller resistivity, and thus has a better current transmission effect.

[0048] For example, in the first cross section, the cross-sectional area of ​​the metal inner core 21 may be 0.00785 mm 2 、0.0085mm 2 、0.009mm 2 、0.0095mm 2 , 0.01mm 2 , 0.015mm 2 、0.017mm 2、0.019mm 2 , 0.02mm 2 , 0.025mm 2 、0.027mm 2 , 0.03mm 2 .

[0049] In some embodiments, the metal inner core 21 includes: a copper core. The metal inner core is not only low in cost but also has a good conductive effect. For example, the metal inner core 21 is a circular copper core with a diameter of 0.1 mm to 0.5 mm.

[0050] In some embodiments, in the first cross section, the bonding material 22 covers more than 80% of the outline of the metal inner core 21. In the first cross section, the bonding material 22 covers more of the metal inner core 21. On the one hand, the contact surface between the bonding material and the metal inner core is larger, which is conducive to forming a reliable first alloy layer; on the other hand, in the first cross section, when the cross section of the metal inner core is circular, the bonding material covers the circular metal inner core beyond its center, which can achieve a better effect of covering and clamping the circular metal inner core. When the cross section of the metal inner core is flat, the bonding material covers most of the two sides of the flat metal inner core and even covers its top. It is difficult for the flat metal inner core to escape from the bonding material, thereby achieving a better connection effect. Even if the first alloy layer fails, the metal inner core can still be fixed by the bonding material.

[0051] For example, in the first cross section, the bonding material 22 may cover 80%, 83%, 87%, 85%, 90%, 92.5%, 93%, 95%, 96%, 97%, 98%, 99%, or 100% of the contour of the metal core 21 .

[0052] In some embodiments, Figure 2 As shown, in the first cross section, the width of the bonding material 22 in contact with the electrode 11 and the cell is greater than the width of the metal core 21. The width direction is perpendicular to the length direction of the electrical connector. The upper end of the bonding material contacts the metal core and the lower end contacts the electrode. When the lower end width of the bonding material is larger, the bonding material with the metal core fixed on the cell has a larger contact area, which is conducive to the formation of a good quality and large area alloy layer between the electrode and the bonding material. In addition, the structure with a larger lower end and a smaller upper end is conducive to the fixation of the bonding material and the metal core on the surface of the cell, which can improve the connection reliability of the photovoltaic module.

[0053] In some embodiments, the bonding material is a single bonding material, that is, the bonding material has a single source, and may be the bonding material wrapped around the metal core of the electrical connector 2, or the bonding material is a bonding material that is separately disposed between the metal core and the electrode.

[0054] In some embodiments, the bonding material includes a first bonding material 221 and a second bonding material 222. The first bonding material 221 covers the outer periphery of the metal core, and the second bonding material 222 covers the bottom and at least part of the side of the first bonding material. Figure 4 The second bonding material here is set in a process independent of the first bonding material, such as solder paste. The source of this bonding material is flexible and diverse, and is suitable for a variety of scenarios. The second bonding material can supplement the first bonding material, enhance the bonding strength between the electrode and the metal core, and also increase the contact area between the first bonding material and the battery cell, thereby increasing the area of ​​the second alloy layer. Figure 4 It can be seen that due to the provision of the second bonding material, the volume of the bonding material increases, and its coating and fixing effect on the side surface of the metal inner core is significantly enhanced.

[0055] The following is a detailed introduction to the main contents of the second level. Figure 1 A second alloy layer 32 is formed between the electrode 11 and the bonding material 22. The second alloy layer 32 acts as an electrical and mechanical connector between the electrode 11 and the bonding material 22, reliably and firmly electrically connecting the electrode 11 and the bonding material 22, thereby achieving reliable and effective collection of current.

[0056] As mentioned above, the main component of the bonding material 21 is tin, and the material of the electrode 11 is usually silver, copper, nickel, etc. Therefore, the second alloy layer 32 includes: silver-tin intermetallic compound (such as Ag3Sn) or copper-tin intermetallic compound, tin-nickel intermetallic compound. The above-mentioned electrode has good electrical conductivity, and the resistivity of the above-mentioned second alloy layer 32 is low and the electrical conductivity is good. There is no specific limitation on the mass ratio of tin and silver in the silver-tin intermetallic compound. There is no specific limitation on the mass ratio of copper and tin in the copper-tin intermetallic compound. There is no specific limitation on the mass ratio of nickel and tin in the tin-nickel intermetallic compound.

[0057] In some embodiments, reference Figure 1, on one surface of a battery cell 1, the total length of the second alloy layer at the position of an electrical connector 2 is L1, where the surface refers to the surface of the battery cell where the electrode 11 is set, which can refer to only the backlight surface, or can be the light-facing surface and the backlight surface. During the normal operation of the battery cell, the main absorption surface is its light-facing surface, and the backlight surface and the light-facing surface are opposite. The electrical connector can be a welding strip, or it can be a conductive layer on a conductive backplane that connects adjacent battery cells. The length of the portion of an electrical connector 2 located on the surface of the battery cell is L2, and the direction of the length is parallel to the extension direction of the electrical connector 2. Usually, an electrical connector 2 needs to extend from the vicinity of the head of a battery cell, across the gap between two battery cells, to the vicinity of the tail of another adjacent battery cell. Here, the ratio of L1 to L2 is greater than or equal to 2.1%, that is, the total length L1 of the second alloy layer at the position of an electrical connector on one surface of a battery cell 1 is greater than or equal to 2.1% of the length L2 of the portion of an electrical connector located on the surface. When the total length L1 of the second alloy layer on one surface of a cell 1, that is, the portion where the electrode and the electrical connector realize alloying connection accounts for more than 2.1% of the length of the electrical connector, on the one hand, it can ensure that the current has sufficient collection and transmission channels, and the current collection effect is good; on the other hand, the electrode and the electrical connector have sufficient alloy connection to ensure the reliability of the connection of the electrical connector. When the ratio of L1 to L2 is less than 2.1%, the current collection and transmission channels are insufficient, and there is a certain loss in the current collection, which will reduce the performance of the photovoltaic module. It should be noted that the cell here is applicable to both cells with busbars and cells without busbars, and the ratio of L1 to L2 is greater than or equal to 2.1%. For example, the ratio of L1 to L2 here can be 2.1%, 2.3%, 2.5%, 2.2%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.5%.

[0058] Optionally, on one surface of a battery cell 1, the second alloy layer at the position of an electrical connector 2 can be divided into multiple parts on the battery cell, specifically, it can be divided into more than 5 connection points. For example, 6, 7, 8, 10 connection points, or even 20 connection points. And the spacing difference between each connection point is less than 5mm. For example, the spacing difference between the connection points is 5mm, 4mm, 3mm, 2mm, 1mm, 0.5mm, etc. At this time, the second alloy layer of an electrical connector on the battery cell is not designed in a centralized manner, but is multi-point and relatively evenly distributed. This design makes the points where current converges on the electrical connector more dispersed and more uniform, which is conducive to rapid current collection and reduced current loss. Moreover, compared with concentrating on one point for connection and fixation, this design has a better fixing effect with multi-point and relatively uniform fixed connection, and is not prone to problems such as local detachment and warping of the electrical connection line.

[0059] It should be noted that, when there are multiple electrical connectors on one surface of a battery cell, one of the electrical connectors can achieve a certain effect if it meets the above design. L1 and L2 are the total length of an electrical connector and the second alloy layer below it on one surface of the battery cell. On one surface of the battery cell, the second alloy layer is roughly distributed in an array.

[0060] In some embodiments, the cell includes a first surface and a second surface relative to each other, one of the first surface and the second surface is a light-facing surface and the other is a backlight surface, and electrodes are provided on both the first surface and the second surface, that is, the cell is a cell with electrodes on both sides. For the first surface and the second surface, the ratio of L1 to L2 is greater than or equal to 2.85%. It should be understood that the value of L1 here is still the total length of the second alloy layer at an electrical connection position on a cell surface. For the first surface, the ratio of L1 to L2 is greater than or equal to 2.85%. The second surface is set similarly. For the light-facing surface and the backlight surface of the double-sided cell, the total length of the second alloy layer on the two surfaces accounts for more than 2.85%, which can make the current collection of the two surfaces more balanced, reduce the current loss problem caused by current mismatch, and improve the stability and balance of the connection force of the electrical connectors on the two surfaces, and reduce the problems of hidden cracks and fragments caused by uneven tension on the two opposite surfaces of the cell. It should be noted that, no matter the cell is a cell with a busbar line or a cell without a busbar line, the ratio of L1 to L2 is greater than or equal to 2.85%.

[0061] For example, the cell includes a first surface and a second surface opposite to each other, and electrodes are disposed on the first surface and the second surface. For the first surface and the second surface, the ratio of L1 to L2 may be 2.85%, 2.9%, 2.91%, 2.92%, 2.98%, 3%, 3.1%, 3.4%, 3.2%, 3.5%. For another example, the cell includes a first surface and a second surface opposite to each other, and electrodes are disposed on the first surface and the second surface. For the first surface and the second surface, for a cell with a busbar line, L1 may be about 7.12 mm, for a cell without a busbar line, L1 may be about 2.997 mm, and L2 is approximately 80 mm to 105 mm.

[0062] The bifacial cell here may be a TOPCon (passivated contact) cell, a heterojunction cell, etc., and there is no limitation on the specific type of the cell.

[0063] In some embodiments, the cell comprises a first surface and a second surface opposite to each other, one of the first surface and the second surface is a light-facing surface and the other is a backlight surface, and an electrode is arranged only on the first surface, and the first surface here may refer to a backlight surface, that is, the cell is a back-contact or single-sided cell. For the first surface, the ratio of L1 to L2 is greater than or equal to 4.2%, and for a cell with electrodes arranged on a single side or a back-contact cell with electrodes on the backlight surface, the electrodes and the electrical connectors connecting the electrodes are both located on one side of the cell surface, and at this time, the design appropriately increases the area of ​​the second alloy layer corresponding to an electrical connector, that is, appropriately increases the alloy connection area between the electrode and the electrical connector, so as to disperse the force and the current convergence point, on the one hand, improve the current convergence and transmission effect, and improve the connection stability, on the other hand, make the force between the electrical connector and the cell more uniform and dispersed, reduce the risk of hidden cracks and fragments of the cell, and at the same time, the current convergence efficiency can be improved and the loss can be reduced by converging current at multiple points and in a larger area.

[0064] It should be noted that, no matter the cell has a busbar or no busbar, the ratio of L1 to L2 is greater than or equal to 4.2%. For example, the cell includes a first surface and a second surface opposite to each other, and electrodes are only provided on the first surface. For the first surface, the ratio of L1 to L2 can be 4.2%, 4.25%, 4.5%, 4.6%, 4.98%, 4.77%, 5%, 5.2%, 5.3%, 5.5%, 10.47%, 12.94%, 4.995%. For another example, the cell includes a first surface and a second surface opposite to each other, and electrodes are only provided on the first surface. For the first surface, for a cell with a busbar, L1 can be about 11 mm, and for a cell without a busbar, L1 can be about 2.16 mm to 5.4 mm or about 10.48 mm, and L2 is approximately 80 mm to 105 mm.

[0065] The single-sided cell or back-contact cell here can be a back-contact heterojunction cell, an interdigitated back-contact cell, a back-contact cell with a tunneling passivation layer, etc., and there is no limitation on the specific type of the cell.

[0066] In some embodiments, the electrode 11 includes a collector electrode, and the extension direction of the collector electrode is parallel to the extension direction of the electrical connector. The collector electrode is arranged corresponding to the N-type doped layer and the P-type doped layer. There is usually no busbar line in the cell, and the electrical connector is directly arranged on the collector electrode, so the ratio of L1 to L2 is greater than or equal to 60%. That is, on one surface of the cell, the total length of the second alloy layer at the position of an electrical connector is L1, and the length of the part of an electrical connector located on one surface of the cell is L2, and the ratio of L1 to L2 is greater than or equal to 60%. For the photovoltaic module, the length of the second alloy layer is greatly increased, that is, the length of an electrical connector for current convergence and fixed connection is greatly increased, so that better current convergence effect and electrical connection reliability can be obtained.

[0067] Further, the electrode 11 includes a collector electrode, the extension direction of the collector electrode is parallel to the extension direction of the electrical connector, and the ratio of L1 to L2 can be 80% to 90%. For example, the electrode 11 includes a collector electrode, the extension direction of the collector electrode is parallel to the extension direction of the electrical connector, and the ratio of L1 to L2 can be 60%, 65%, 70%, 72%, 75%, 80%, 83%, 85%, 89%, 90%. At this time, the current convergence and electrical connection effects of the electrical connector can be further improved.

[0068] In some embodiments, on one surface of a cell 1: the total length of the second alloy layer 32 at the position of an electrical connector 2 is L1. On one surface of a cell 1: the total length of the first alloy layer at the position of an electrical connector 2 is L3, and the direction of the length is parallel to the extension direction of the electrical connector 2. A surface here is also the light-facing surface or the backlight surface of the cell. The ratio of L1 to L3 is greater than or equal to 2%, and the first alloy layer is mainly used to achieve a reliable connection between the metal core and the bonding material, and the second alloy layer is mainly used to achieve a reliable connection between the bonding material and the electrode. When the first alloy layer and the second alloy layer are combined, and the total length of the second alloy layer accounts for more than 2% of the length of the first alloy layer, not only can the bonding material be reliably fixed to the metal core, but also the bonding material can be reliably connected to the electrode. More specifically, when the ratio of L1 to L3 is less than 2%, the current collection and transmission channel is insufficient, and there is a certain loss in the current collection, which will reduce the performance of the photovoltaic module.

[0069] It should be noted that, regardless of whether the cell has a busbar or not, the ratio of L1 to L3 is greater than or equal to 2%. For example, the ratio of L1 to L3 can be 2%, 2.2%, 2.5%, 2.6%, 2.75%, 2.9%, 3%, 3.1%, 3.2%, or 3.4%. It should be noted that, in the case of multiple electrical connectors on one surface of a cell, the alloy layer design of at least one electrical connector meets the above design. Of course, when the alloy layer design of more or all electrical connectors meets the above design, the electrical connection reliability and current transmission effect of the photovoltaic module are better.

[0070] In some embodiments, an electrical connector 2 connects two adjacent battery cells 1, and there are multiple second alloy layers 32 between the electrical connector and the two battery cells 1. Along the length direction of the electrical connector 2, the length of the second alloy layer located at the head and / or tail is greater than the length of the second alloy layer located in the middle. Along the length direction of the electrical connector 2, the second alloy layer located at the head and / or tail is mainly the second alloy layer at the end of the electrical connector. Compared with the second alloy layer located in the middle, the end position is more prone to bending, warping, etc., so the connection quality of the second alloy layer located at the end has a greater impact on the electrical connector and the two battery cells 1. In this application, the length of the second alloy layer located at the end position is longer, and the second alloy layer located at the end position can be compatible with possible bending, warping, etc., and can still maintain a good conductive effect under the above possible adverse effects. There is no limit on the number of second alloy layers contained in an electrical connector.

[0071] Optionally, on the battery cell, a connecting portion is provided at the end of the electrical connector, and the width of the connecting portion is greater than the width of the collector electrode. The end of the electrical connector extends beyond the center of the connecting portion. In this case, the contact length between the end of the electrical connector and the connecting portion is large, making it easy to achieve reliable electrical connection and avoid the end of the electrical connector from being lifted or detached.

[0072] The following is a detailed introduction to the main contents of the third level. At a connection point between the electrical connector 2 and the electrode 1, the width of the second alloy layer 32 is greater than or equal to 0.3 times the width of the metal core 21. The direction of the width is perpendicular to the extension direction of the electrical connector 2 and to the thickness direction Q of the battery cell. At a single connection point, the width of the second alloy layer 32 is relatively large, which can achieve a larger electrical connection between the connection point and the electrical connector 2, and a more secure and reliable connection. Specifically, there can be multiple connection points on the electrode 1, for example, there are 7 to 20 connection points on an electrode 1, and each of the above-mentioned connection points of the electrode forms a second alloy layer between the bonding material. If the width of the second alloy layer is less than 0.3 times the width of the metal core, the coverage of the second alloy layer is relatively small, and the second alloy layer at the connection point is prone to separation when the photovoltaic module is bent.

[0073] For example, at a connection point between the electrical connector 2 and the electrode 1, the width of the second alloy layer 32 can be 0.3 times, 0.5 times, 0.6 times, 0.62 times, 0.55 times, 0.65 times, 0.69 times, 0.7 times, 0.71 times, 0.72 times, 0.75 times, 0.8 times, 1 times, 1.5 times, 2 times, 3 times, etc., of the width of the metal core 21.

[0074] In some embodiments, reference Figure 1 , the electrical connector 2 is a flat electrical connector, and in the aforementioned first cross section, the shape of the electrical connector 2 is roughly rectangular, square, or rectangular with chamfers, etc. Compared with circular electrical connectors, the contact between the flat electrical connector and the electrode is mainly surface-to-surface contact. Compared with the surface-to-line contact between the electrode and the circular electrical connector, the surface-to-surface contact has a larger contact area, a more stable interconnection, and a higher interconnection reliability. Moreover, without reducing the cross-sectional area (without increasing the resistivity), the flat electrical connector can be realized by increasing the width and reducing the thickness. The thinned flat electrical connector can greatly reduce the risk of hidden cracks and splits in the battery cell.

[0075] In some embodiments, the electrical connector 2 is a flat electrical connector. At a connection point between the electrical connector 2 and the electrode 1, the ratio of the width of the metal core 21 to the width of the second alloy layer 32 is 1: (1 to 4), that is, for the flat electrical connector, at a connection point, the width of the second alloy layer 32 is greater than the width of the metal core, so that the second alloy layer located at the lower side is wider than the metal core located at the upper side, so that the second alloy layer can fix the metal core well. In addition, the contact position between the bonding material and the electrode is usually weakly connected and prone to cracking. When the width of the second alloy layer is greater than the metal core, the connection width is larger, and the corresponding connection strength is larger. From the metal core to the bonding material and the electrode, the second alloy layer, that is, the connection base, is more stable. In addition, the width of the second alloy layer is less than 4 times the width of the metal core, which can appropriately reduce the amount of bonding material used and the coverage range, avoid excessive material costs, and avoid the bonding material affecting other adjacent electrodes. The direction of the width is perpendicular to the extension direction of the electrical connector 2 and perpendicular to the thickness direction L2 of the battery cell 1. The width of the second alloy layer can be determined by measuring the distance between the two ends of the second alloy layer in the width direction, so as to determine whether the process is up to standard and whether the electrical connection of the connection point is up to standard.

[0076] For example, the electrical connector 2 is a flat electrical connector. At a connection point between the electrical connector 2 and the electrode 1, the ratio of the width of the metal core 21 to the width of the second alloy layer 32 can be 1:1, 1:1.2, 1:1.5, 1:1.7, 1:2, 1:3.5, 1:2.5, 1:2.4, 1:2.6, 1:2.8, 1:3, 1:3.1, 1:3.7, or 1:4.

[0077] In some embodiments, reference Figure 5 The electrical connector is a circular electrical connector. At a connection point between the electrical connector 2 and the electrode 1, the ratio of the diameter of the metal core 21 to the width of the second alloy layer 32 is 1:(0.3 to 3). The direction of the width is perpendicular to the extension direction of the electrical connector 2 and perpendicular to the thickness direction Q of the battery cell 1. At this single connection point, since the metal core 21 is circular, the bonding material can be in a shell shape to better wrap and fix the metal core. Therefore, the width of the second alloy layer is more than 0.3 times the width of the metal core, which can achieve reliable connection and meet the reliability requirements of the photovoltaic module during service. Moreover, at this time, the ratio of the width of the second alloy layer 32 is more appropriate, achieving a good balance between cost and conductive effect.

[0078] For example, the electrical connector is a circular electrical connector, and at a connection point between the electrical connector 2 and the electrode 1, the ratio of the diameter of the metal core 21 to the width of the second alloy layer 32 is 1:0.3, 1:0.4, 1:0.5, 1:0.55, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.5, 1:1.8, 1:2, 1:2.3, 1:2.5, 1:2.8, 1:3, etc.

[0079] In some embodiments, at a connection point between the electrical connector 2 and the electrode 1, the length of the second alloy layer 32 is greater than or equal to 30 μm, and the direction of the length of the second alloy layer 32 is parallel to the extension direction of the electrical connector 2. At a single connection point, the length of the second alloy layer is large, the connection between the connection point and the electrical connector is relatively firm and reliable, and the connection effect of the photovoltaic module is excellent.

[0080] For example, at a connection point between the electrical connector 2 and the electrode 1, the length of the second alloy layer 32 can be 30μm, 40μm, 50μm, 60μm, 70μm, 90μm, 100μm, 200μm, 500μm, 800μm, 1000μm, 1500μm, 2000μm, etc.

[0081] The second alloy layer 32 is laid flat on the battery cell 1, and the second alloy layer 32 is distributed in a continuous wavy shape. The second alloy layer 32 is mainly an alloy formed by a bonding material and an electrode. The main components of the bonding material are mainly tin, which is unevenly distributed. The wavy shape makes it easier to form a continuous IMC, further ensuring that the metal core and the electrode are completely covered, and the reliability of the electrical connection is improved. Moreover, the wavy morphology can also disperse stress and avoid stress concentration. The state of the second alloy layer 32 is usually not to wrap or surround the electrode, so that no matter what shape the metal core or electrical connector is, it forms a surface-to-surface contact with the electrode, with a larger contact area, greater bonding force and better connection reliability. In the wavy second alloy layer 32 here, the distance between the trough and the peak can be 0.5μm to 2μm, the thickness of the second alloy layer 32 is more appropriate, the conductive effect is good, and the second alloy layer is not too thick, because the thickness of the second alloy layer is too large and it is easy to break brittlely.

[0082] In some embodiments, the thickness of the second alloy layer 32 is 1 μm to 5 μm, and the thickness direction can be parallel to the thickness direction Q of the battery cell. The thickness of the second alloy layer is relatively appropriate, which can not only ensure the connection quality and avoid the electrical connection failing to meet the standards due to too little IMC, but also prevent the IMC from being too thick. Because the IMC is too thick and brittle, it is easy to break, which can improve the reliability of the electrical connection and the connection of the battery cell.

[0083] For example, the thickness of the second alloy layer 32 may be 1 μm, 1.2 μm, 1.5 μm, 1.7 μm, 2 μm, 2.1 μm, 2.5 μm, 2.8 μm, 3 μm, 3.1 μm, 3.5 μm, 4 μm, 4.5 μm, or 5 μm.

[0084] In some embodiments, the second alloy layer includes 32: a silver-tin intermetallic compound or a copper-tin intermetallic compound or a nickel-tin intermetallic compound. The second alloy layer is an alloy formed between a bonding material and an electrode. Different choices of bonding materials and electrode materials can form alloy layers of different materials. When the second alloy layer includes a silver-tin intermetallic compound or a copper-tin intermetallic compound or a nickel-tin intermetallic compound, the second alloy layer of such material has relatively stable properties, better electrical conductivity, stronger connection reliability and is easy to implement in terms of process. There is no specific limitation on the mass ratio of tin and silver in the silver-tin intermetallic compound. There is no specific limitation on the mass ratio of copper and tin in the copper-tin intermetallic compound. There is no specific limitation on the mass ratio of nickel and tin in the nickel-tin intermetallic compound.

[0085] In some embodiments, the plane perpendicular to the thickness direction Q of the battery cell 1 is the first plane, and the first plane is parallel to the extension direction of the electrical connector. On the same first plane: the first projection of the second alloy layer 32 intersects with the second projection of the metal inner core 21, and the ratio of the intersection area to the area of ​​the second projection is greater than or equal to 50% and less than or equal to 100%. At this time, the area of ​​the intersection of the two accounts for a large proportion of the area of ​​the second projection of the metal inner core 21, which can avoid the electrical connector being set too biased and reduce the risk of pulling off. More specifically, in the process of forming an electrical connection, the electrical connector may be offset a little and may not be located in the middle of the connection point of the electrode. Due to the leveling of the bonding material, the second alloy layer will usually be located in the center of the connection point of the electrode. The metal core of the electrical connector may be off-center. From a top view, the metal core and the second alloy layer may not overlap 100%. The overlapping area between the two accounts for 50% to 100% of the projected area of ​​the metal core. The circular electrical connector may roll, and the alignment of the flat electrical connector may have precision errors. However, under normal circumstances, the connection point of the electrode is fixed, so the position of the second alloy layer is roughly fixed or determined, and the position of the electrical connector will be offset. The present application limits the offset of the electrical connector to a smaller level, further improving the connection effect and reducing the risk of pulling off.

[0086] For example, the plane perpendicular to the thickness direction Q of the battery cell 1 is the first plane, and the first plane is parallel to the extension direction of the electrical connector. On the same first plane: the first projection of the second alloy layer 32 intersects with the second projection of the metal core 21, and the ratio of the intersection area to the area of ​​the second projection can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%.

[0087] In some embodiments, a connecting portion is provided on the battery cell 1, and the connecting portion may be a pad or a thickened section on a collector electrode, etc., and the bonding material 21 is fixed and electrically connected to the electrode 1 through the connecting portion. On the battery cell 1, the width of the connecting portion is greater than or equal to the width of the electrode, the width of the connecting portion is larger, and the connection area between the connecting portion and the bonding material is larger, so that the bonding material has a larger attachment area on the battery cell, which can improve the connection reliability of the bonding material and the electrical connector, and can also improve the current convergence and transmission effect. In addition, it can also prevent the bonding material from overflowing the connecting portion.

[0088] In some embodiments, the surface of the connection part close to the electrical connector 2 is the third surface, and the third surface is the surface of the connection part facing away from the battery cell. The second alloy layer 32 covers at least 20% of the third surface, and the second alloy layer exceeds the third surface by at most 20%. On the one hand, the second alloy layer covers a relatively large amount of the third surface, ensuring the reliability of the electrical connection. On the other hand, the part of the second alloy layer that exceeds the connection part is small, and the risk of short circuit is small. Specifically, when the main component of the bonding material includes tin, the connection part has a certain gripping effect on the tin in the bonding material, further avoiding the bonding material overflowing the connection part.

[0089] In some embodiments, reference Figure 6 , an electrical connector 2 connects two adjacent battery cells 1, Figure 6 In the figure, the black dot 111 is a schematic diagram of the connection part. The battery cell 1 on the left can be the previous battery cell, and the battery cell 1 on the right can be the next battery cell. The length from the first position of the tail connection part connecting the previous battery cell to the second position of the head connection part of the adjacent next battery cell 1 is L4. The distance between adjacent connection parts 111 on a battery cell 1 is L5. The ratio of L5 to L4 is 1: (0.8-1.5). The position connected to each connection part 111 on an electrical connector is each force application point, and then the distribution of each force application point on an electrical connector is relatively uniform, that is, the shear force on each IMC is basically uniform, ensuring the reliability of the IMC and avoiding failure. It should be noted that there is no specific limit on how many connection parts are set on a battery cell 1.

[0090] For example, an electrical connector 2 connects two adjacent battery cells 1. The length between the first position of the tail connection portion of the previous battery cell and the second position of the head connection portion of the adjacent rear battery cell on the electrical connector 2 is L4. The distance between adjacent connection portions 111 on a battery cell 1 is L5. The ratio of L5 to L4 can be 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, or 1:1.15.

[0091] In some embodiments, in the direction perpendicular to the extension direction of the electrical connector 2 and the thickness direction Q of the battery cell, the distance between the centers of adjacent connection parts on the same side of the battery cell 1 is less than or equal to 2 mm, that is, in the direction perpendicular to the length direction and the Q direction of the electrical connector, the centers of adjacent connection parts are as collinear as possible, and thus the force acting on the electrical connector is relatively uniform over the entire electrical connector, and the connection is more reliable. That is, in the direction perpendicular to the extension direction of the electrical connector 2 and the thickness direction Q of the battery cell 1, the alignment error between adjacent connection parts is small, and the entire electrical connector does not need to be twisted to a large extent to adapt to the alignment error between the connection parts, that is, the degree of twisting of the entire electrical connector is small, and the shear force introduced into the electrical connector is small, and thus the shear force acting on the electrical connector over the entire electrical connector is small, and the connection is more reliable.

[0092] For example, in a direction perpendicular to the extension direction of the electrical connector 2 and the thickness direction Q of the battery cell, the distance between the centers of adjacent connection parts on the same side of the battery cell 1 can be 2mm, 1.8mm, 1.5mm, 1.3mm, 1.1mm, 1mm, 0.9mm, 0.8mm, 0.5mm, 0.4mm, 0.3mm, 0.2mm, 0.1mm, 0.05mm, 0.01mm, 0, etc.

[0093] In some embodiments, at least two sizes of connection parts are included on the same cell 1, that is, there are large connection parts and small connection parts on the same cell. The large connection part can improve the current carrying capacity, enhance the mechanical connection strength, and improve the connection reliability. The small connection part can reduce shading and save space. Therefore, the photovoltaic module of the present application not only ensures the contact area and the IMC area, but also has better connection reliability, lower resistance and less shading. It should be noted that the large connection part here can be located at the edge of the cell, and the small connection part is located on the inner side of the large connection part. The large connection part is located at the edge of the cell, which can improve the current collection effect at the edge of the cell.

[0094] The following is a detailed introduction to the main content of the fourth level. The second cross section of the photovoltaic module is parallel to the extension direction of the electrical connector 2 and perpendicular to the first cross section. In the first cross section or the second cross section, refer to Figure 7The second alloy layer 32 includes discrete second alloy points 321, and the discrete second alloy points 321 can evenly bear the connection force, which can improve the reliability and stability of the connection. The electrode here can be a low-temperature electrode, and the sintering temperature of the low-temperature electrode is lower than the sintering temperature of the high-temperature electrode. The main material of the low-temperature electrode can be selected from: micro-nano silver material, micro-nano silver-coated copper material, nano silver material, micron copper material, nano copper material, etc., and the above materials have good electrical conductivity and good bonding strength. More specifically, since the low-temperature electrode slurry is mainly composed of micron spherical metal particles and micro-particle flake metal bonded by organic matter, the surface of the low-temperature silver paste is uneven after solidification into a "bumpy" uneven shape, and after the electrode is formed, the metal group in the electrode is more dispersed. In this case, the discrete second alloy points are conducive to the formation of sufficient connecting alloys between the electrode and the bonding material, and the discrete second alloy points can realize multi-point contact between the electrode and the bonding material, which can not only realize stress dispersion, but also can realize reliable electrical connection between the electrode and the bonding material through multi-point second alloy points. It should be noted that there is still a continuous second alloy in the second alloy layer.

[0095] In some embodiments, the length of the second alloy point 321 is less than or equal to 2 μm. The length of the second alloy point 321 is the maximum size of the second alloy point 321 in the aforementioned first section or second section, that is, the maximum size of the second alloy point 321 will not exceed 2 μm. The second alloy point 321 is small in size and more evenly distributed, which can further evenly bear the connection force and improve the reliability and stability of the connection.

[0096] For example, the length of the second alloy dots 321 may be 2 μm, 1.9 μm, 1.8 μm, 1.5 μm, 1.3 μm, 1 μm, 0.9 μm, 0.8 μm, 0.5 μm, 0.2 μm, 0.1 μm, 0.05 μm, 0.01 μm, 0.03 μm, or 0.005 μm.

[0097] In some embodiments, for a battery cell 1, the spacing between adjacent discrete second alloy points 321 is less than or equal to 1 μm. The smaller the spacing between adjacent discrete second alloy points 321, the better the conductive effect.

[0098] For example, for one battery cell 1 , the spacing between adjacent discrete second alloy points 321 may be 1 μm, 0.9 μm, 0.8 μm, 0.5 μm, 0.3 μm, 0.1 μm, 0.09 μm, 0.05 μm, 0.03 μm, 0.01 μm, or 0.005 μm.

[0099] In some embodiments, bonding materials and / or electrode materials are filled between adjacent discrete second alloy dots 321. Both bonding materials and electrode materials have good electrical conductivity, which can improve the current transmission effect, and the above materials have a certain viscosity and can also improve the bonding force.

[0100] In some embodiments, the electrode is printed on the surface of the cell, and the surface of the cell has a velvet structure. That is, the electrode with discrete second alloy points can be applied on the surface with a velvet structure, and these discrete second alloy points make the electrode and the velvet structure have good grip, better pull-off force, and better electrical connection reliability. It should be noted that the electrode can also be applied on a polished surface, but the connection force between the electrode and the velvet structure is greater.

[0101] Figure 1 In the figure, the direction perpendicular to the paper surface is the length extension direction of the metal inner core 21 or the extension direction of the metal inner core 21. In some embodiments, in the first cross section, the distance between the metal clusters in the electrode is less than or equal to 10 μm, and the first cross section is a cross section perpendicular to the length extension direction of the metal inner core 21 in the photovoltaic module. The electrode slurry usually contains metal particles and organic matter. During the drying and curing process, the metal particles will aggregate, and the aggregated metal particles may be separated by the above-mentioned organic matter. The aggregated metal particles are the metal clusters here. The distance between the metal clusters is small, the metal density is large, the electrode has good conductivity, and the current collection effect is good.

[0102] For example, in the first cross section, the distance between metal groups in the electrode may be 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 2 μm, 1 μm, 0.8 μm, 0.5 μm, 0.1 μm, or 0.01 μm, which refers to the minimum distance between two metal groups.

[0103] In some embodiments, in the photovoltaic module of the present application, the connection tension between the high-temperature electrode and the electrical connector can be greater than or equal to 1.5N / mm 2 The connection tension between the low temperature electrode and the electrical connector can be greater than or equal to 1.2N / mm 2 The main differences between high temperature electrodes and low temperature electrodes are, first, the different material compositions and second, the different sintering temperatures. The sintering temperature of high temperature electrodes is usually higher than that of low temperature electrodes, and high temperature electrodes usually contain glass powder, etc. For both high temperature electrodes and low temperature electrodes, the lower limit of the connection tension is set appropriately, which not only ensures the connection quality, but also avoids the problem of brittleness and easy breakage caused by excessive connection.

[0104] In some embodiments, an electrical connector 2 connects two adjacent battery cells 1. In a direction perpendicular to both the extension direction of the electrical connector 2 and the thickness direction Q of the battery cell 1, the distance between the edges of the two adjacent battery cells is less than or equal to 3 mm. In a direction perpendicular to both the extension direction of the electrical connector 2 and the thickness direction Q of the battery cell 1, the alignment error between adjacent battery cells is small, and the entire electrical connector does not need to be twisted to a large extent to accommodate the alignment error between the battery cells. That is, the degree of twisting of the entire electrical connector is small, and the shear force introduced into the electrical connector is small. Therefore, the shear force acting on the entire electrical connector is small, and the connection is more reliable.

[0105] For example, an electrical connector 2 connects two adjacent battery cells 1; in a direction perpendicular to both the extension direction of the electrical connector 2 and the thickness direction Q of the battery cell 1, the distance between the edges of two adjacent battery cells can be 3mm, 2.5mm, 1m, 2m, 1.5mm, 1.2mm, 3mm, 0.9mm, 0.8mm, 0.1mm, or 0.01mm.

[0106] In some embodiments, reference Figure 6 An electrical connector 2 connects two adjacent battery cells 1. Along the extension direction of the electrical connector 2, the electrical connector 2 covers 70% to 95% of the length of the battery cell 1. The coverage ratio of the length of the battery cell by the electrical connector 2 is relatively appropriate, which can ensure sufficient electrical connection area and reliable current transmission, not only reducing the current transmission loss, but also reducing the heat impact on the battery cell during the electrical connection process.

[0107] For example, an electrical connector 2 connects two adjacent battery cells 1. Along the extension direction of the electrical connector 2, the length of the battery cell 1 covered by the electrical connector 2 can be 70%, 73%, 75%, 79%, 80%, 85%, 88%, 90%, 92%, 95%, 91%, 87.5%, or 84%.

[0108] In some embodiments, the electrical connector mentioned in the full text may be a solder strip, and the main material of the bonding material includes tin, for example, the bonding material is solder paste, tin-lead alloy, tin-lead-bismuth alloy, etc. The electrical connector 2 is electrically connected and fixed to the electrode of the battery cell through a welding process and / or a lamination bonding process. The welding process is to directly weld the electrode of the battery cell and the solder strip together. The lamination bonding process may be to pre-fix the solder strip and the electrode of the battery cell, and then use the thermal environment during the lamination process to achieve electrical connection between the solder strip and the electrode. The electrical connection process is flexible and diverse, and can be adapted to a variety of scenarios. The welding process here may refer to high-temperature infrared welding or low-temperature infrared welding, etc.

[0109] It should be noted that the aforementioned four levels of the present application are detailed records of the photovoltaic components of the present application from different perspectives. The relevant parts of the four levels can be referenced to each other. In order to avoid repetition, the relevant parts are briefly described.

[0110] The present application also provides a photovoltaic system, which includes any of the aforementioned photovoltaic components arranged in a plurality of arrays. The form of the photovoltaic system is not specifically limited. For example, the photovoltaic system can directly exist as a building roof, or the photovoltaic system can be set on the building roof. Other structures of the photovoltaic system are not specifically limited. Compared with photovoltaic components, the photovoltaic system can further expand the application scenarios of solar cells.

[0111] The photovoltaic system has the same or similar beneficial effects as any of the aforementioned photovoltaic modules, and the relevant parts can be referenced to each other. In order to avoid repetition, they will not be described here.

[0112] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0113] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A photovoltaic module, characterized in that: include: Battery cells; The battery cell is provided with electrodes; An electrical connector having a metal inner core; The metal inner core is electrically connected to electrodes of two adjacent battery cells through a bonding material; a first alloy layer is formed between the bonding material and the metal inner core; A cross section perpendicular to the length extension direction of the metal inner core is a first cross section, and in the first cross section, the first alloy layer covers more than 80% of the contour line of the metal inner core.

2. The photovoltaic module according to claim 1, characterized in that: In the first cross section, the first alloy layer covers more than 90% of the outline of the metal core.

3. The photovoltaic module according to claim 1, characterized in that: In the first cross section, the first alloy layer includes: an inner contour and an outer contour; the length of the outer contour and the circumference of the contour line of the metal inner core have a ratio of (0.8 to 5):

1.

4. The photovoltaic module according to claim 1, characterized in that: The thickness of the first alloy layer is 0.5 μm to 4 μm.

5. The photovoltaic module according to claim 1, characterized in that: The first alloy layer surrounds the metal core in a wave shape; and / or, a main component of the first alloy layer includes a tin-copper intermetallic compound.

6. The photovoltaic module according to claim 1, characterized in that: In the first cross section, the first alloy layer includes: an inner contour and an outer contour; The metal inner core is a circular metal inner core, and the ratio of the perimeter of the contour line of the metal inner core to the length of the outer contour of the first alloy layer is 2πx:2π(x+0.5) to 2πx:2π(x+4); x is the radius of the metal inner core, in mm; and / or, The metal inner core is a flat metal inner core, and the ratio of the perimeter of the contour line of the metal inner core to the length of the outer contour of the first alloy layer is 2(a+b):2(a+0.5)(b+0.5) to 2(a+b):2(a+4)(b+4); a is the width of the metal inner core, b is the thickness of the metal inner core, and the units of a and b are both mm; and / or, The metal inner core is a triangular metal inner core, and the ratio of the circumference of the contour line of the metal inner core to the length of the outer contour of the first alloy layer is (m+n+p): (m+n+p+1.5) to (m+n+p): (m+n+p+12); m, n, and p are respectively the side lengths of the cross-section of the metal inner core, and the units are all mm.

7. The photovoltaic module according to claim 1, characterized in that: In the first cross section, the cross-sectional area of ​​the metal inner core is greater than or equal to 0.00785 mm 2 , and / or, the metal inner core includes: a copper core.

8. The photovoltaic module according to claim 1, characterized in that: In the first cross section, the bonding material covers more than 80% of the outline of the metal inner core; and / or the width of the bonding material in contact with the electrode is greater than the width of the metal inner core.

9. The photovoltaic module according to claim 1, characterized in that: The bonding material is a single bonding material; and / or, The bonding material includes a first bonding material and a second bonding material. The first bonding material covers the outer periphery of the metal inner core, and the second bonding material covers the bottom and at least a portion of the side surfaces of the first bonding material.

10. The photovoltaic module according to claim 1, characterized in that ,, a second alloy layer is formed between the electrode and the bonding material.

11. The photovoltaic module according to claim 10, characterized in that ，， On one surface of one of the battery cells, the total length of the second alloy layer at the location of one of the electrical connectors is L1; The length of a portion of the electrical connector located on the surface of the battery cell is L2; ​​the direction of the length is parallel to the extension direction of the electrical connector; The ratio of L1 to L2 is greater than or equal to 2.1%.

12. The photovoltaic module according to claim 11, characterized in that ,, the battery cell comprises: a first surface and a second surface opposite to each other; electrodes are arranged on the first surface and the second surface; For the first surface and the second surface, the ratio of L1 to L2 is greater than or equal to 2.85%.

13. The photovoltaic module according to claim 11, characterized in that ,, the battery cell comprises: a first surface and a second surface opposite to each other; electrodes are arranged only on the first surface; For the first surface, a ratio of L1 to L2 is greater than or equal to 4.2%.

14. The photovoltaic module according to claim 11, characterized in that: The electrodes include: a collector electrode, the extension direction of the collector electrode is parallel to the extension direction of the electrical connector; The ratio of L1 to L2 is greater than or equal to 60%.

15. The photovoltaic module according to claim 10, characterized in that ,, on one surface of the battery cell: the total length of the second alloy layer at the position of the electrical connector is L1, and the total length of the first alloy layer is L3; the directions of the lengths are parallel to the extension direction of the electrical connector; The ratio of L1 to L3 is greater than or equal to 2%.

16. The photovoltaic module according to claim 10, characterized in that: An electrical connector connects two adjacent battery cells, and a plurality of second alloy layers are provided between the electrical connector and the two battery cells. Along the length direction of the electrical connector, the length of the second alloy layer at the head and / or tail is greater than the length of the second alloy layer at the middle.

17. The photovoltaic module according to claim 10, characterized in that ,, at a connection point between the electrical connector and the electrode, the width of the second alloy layer is greater than or equal to 0.3 times the width of the metal inner core; The direction of the width is perpendicular to the extension direction of the electrical connector and perpendicular to the thickness direction of the battery cell.

18. The photovoltaic module according to claim 10, characterized in that ,,The electrical connector includes a flat electrical connector.

19. The photovoltaic module according to claim 18, characterized in that ,, at a connection point between the electrical connector and the electrode, a ratio of a width of the metal inner core to a width of the second alloy layer is 1:(1 to 4); The direction of the width is perpendicular to the extension direction of the electrical connector and perpendicular to the thickness direction of the battery cell.

20. The photovoltaic module according to claim 17, characterized in that ,, the electrical connector includes a circular electrical connector; At a connection point between the electrical connector and the electrode, the ratio of the diameter of the metal inner core to the width of the second alloy layer is 1:(0.3 to 3); The direction of the width is perpendicular to the extension direction of the electrical connector and perpendicular to the thickness direction of the battery cell.

21. The photovoltaic module according to claim 10, characterized in that ,, at a connection point between the electrical connector and the electrode, the length of the second alloy layer is greater than or equal to 30 μm.

22. The photovoltaic module according to claim 10, characterized in that The second alloy layer is spread flat on the battery cell, and the second alloy layer is distributed in a continuous wave shape.

23. The photovoltaic module according to claim 10, characterized in that ,, the thickness of the second alloy layer is 1 μm to 5 μm; And / or, the second alloy layer includes: a silver-tin intermetallic compound or a copper-tin intermetallic compound or a nickel-tin intermetallic compound.

24. The photovoltaic module according to claim 10, characterized in that ,, a plane perpendicular to the thickness direction of the battery cell is a first plane; On the same first plane: the first projection of the second alloy layer intersects with the second projection of the metal core, and the ratio of the intersection area to the area of ​​the second projection is greater than or equal to 50% and less than or equal to 100%.

25. The photovoltaic module according to claim 10, characterized in that A connecting portion is provided on the battery cell, and the bonding material is fixed and electrically connected to the electrode through the connecting portion; on the battery cell, the width of the connecting portion is greater than or equal to the width of the electrode.

26. The photovoltaic module according to claim 25, characterized in that ,, the surface of the connecting portion close to the electrical connector is a third surface; The second alloy layer covers at least 20% of the third surface, and the second alloy layer exceeds the third surface by at most 20%.

27. The photovoltaic module according to claim 25, characterized in that ,, an electrical connector connects two adjacent battery cells; On the electrical connector, the length from the first position of the tail connection portion connected to the previous battery cell to the second position of the head connection portion of the adjacent next battery cell is L4; The distance between adjacent connecting parts on a battery cell is L5; The ratio of L5 to L4 is 1:(0.8-1.5).

28. The photovoltaic module according to claim 25, characterized in that ,, in a direction perpendicular to both the extension direction of the electrical connector and the thickness direction of the battery cell, the distance between the centers of adjacent connecting portions on the same side of the battery cell is less than or equal to 2 mm.

29. The photovoltaic module according to claim 25, characterized in that ,, the same battery cell includes at least two sizes of connecting parts.

30. The photovoltaic module according to any one of claims 10 to 29, characterized in that: In the first cross section or the second cross section, the second alloy layer includes discrete second alloy points; the second cross section is parallel to the extension direction of the electrical connector and perpendicular to the first cross section.

31. The photovoltaic module according to claim 30, characterized in that ,, the length of the second alloy point is less than or equal to 2 μm, and the length of the second alloy point is the maximum size of the second alloy point in the cross section.

32. The photovoltaic module according to claim 30, characterized in that ,, the spacing between adjacent discrete second alloy points is less than or equal to 1 μm.

33. The photovoltaic module according to claim 30, characterized in that Adjacent discrete second alloy points are filled with bonding material and / or electrode material.

34. The photovoltaic module according to claim 30, characterized in that The main material of the electrode is selected from: micron silver material, micron silver-coated copper material, micron copper material, nano silver material, and nano copper material.

35. The photovoltaic module according to claim 30, characterized in that ,, the electrode is printed on the surface of the battery cell, and the surface of the battery cell has a suede structure.

36. The photovoltaic module according to any one of claims 1 to 29, characterized in that: In the first cross section, the distance between the metal groups in the electrode is less than or equal to 10 μm.

37. The photovoltaic module according to any one of claims 1 to 29, characterized in that: One electrical connector connects two adjacent battery cells; in a direction perpendicular to both the extension direction of the electrical connector and the thickness direction of the battery cell, the distance between the edges of the two adjacent battery cells is less than or equal to 3 mm.

38. The photovoltaic module according to any one of claims 1 to 29, characterized in that: An electrical connector connects two adjacent battery cells. Along the extension direction of the electrical connector, the electrical connector covers 70% to 95% of the length of the battery cells.

39. The photovoltaic module according to any one of claims 1 to 29, characterized in that: The electrical connector includes a soldering strip, the main material of the bonding material includes tin, and the electrical connector is electrically connected and fixed to the electrode through a welding process and / or a lamination bonding process.

40. A photovoltaic system, characterized in that: include: Several photovoltaic modules as claimed in any one of claims 1 to 39 are distributed in an array.

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