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; a second alloy layer is formed between the electrode and the bonding material; on one surface of one battery piece, the total length of the second alloy layer at the position of one electric connecting piece is L1; the length of the part, located on the surface of the battery piece, of an electric connecting piece is L2; the direction of the length is parallel to the extension direction of the electric connecting piece; the ratio of L1 to L2 is greater than or equal to 2.1%. According to the photovoltaic module, the connection quality is reliable, the current transmission effect is good, and excessive connection basically does not exist.

Description

[0001] The present application is a divisional application, the parent application date: October 24, 2024, the application number: 202411495763.8, and the invention is named: photovoltaic module and photovoltaic system. TECHNICAL FIELD

[0002] The present application relates to the field of photovoltaic technology, in particular to a photovoltaic module and a photovoltaic system. BACKGROUND

[0003] The process of forming a photovoltaic module includes using an electrical connector to connect two adjacent cells in series. The quality of the series process is directly related to the reliability of the photovoltaic module. If the connection is unstable, the cell string will have phenomena such as virtual connection, white exposure, and short circuit, which will seriously affect the power and performance of the photovoltaic module.

[0004] In existing photovoltaic modules, the connection reliability is poor, which leads to the problem of the electrical connector separating from the cell during the service of the photovoltaic module for many years, affecting the quality and reliability of the photovoltaic module. SUMMARY

[0005] The present application provides a photovoltaic module and a photovoltaic system, which aims to solve the problem of poor connection reliability in existing photovoltaic modules.

[0006] In a first aspect, the present application provides a photovoltaic module, comprising:

[0007] a cell; the cell is provided with an electrode;

[0008] an electrical connector, the electrical connector has a metal inner core;

[0009] The metal inner core electrically connects the electrodes of two adjacent cells through a bonding material; a first alloy layer is formed between the bonding material and the metal inner core;

[0010] A second alloy layer is formed between the electrode and the bonding material;

[0011] The total length of the second alloy layer at the position of the electrical connector on one surface of one cell is L1;

[0012] The length of the part of the electrical connector located on the surface of the cell is L2; the direction of the length is parallel to the extension direction of the electrical connector;

[0013] The ratio of L1 to L2 is greater than or equal to 2.1%; and / or, on one surface of one cell: the total length of the first alloy layer is L3; the ratio of L1 to L3 is greater than or equal to 2%.

[0014] The ratio of L1 to L2 is greater than or equal to 2.1%, which can ensure that the current has sufficient collection 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 electrical connector connection. When the ratio of L1 to L2 is less than 2.1%, the current collection transmission channel is not enough, and the current collection has a certain loss, which will reduce the performance of the photovoltaic module.

[0015] The first alloy layer is mainly used to realize reliable connection of the metal inner core and the bonding material, and the second alloy layer is mainly used to realize reliable connection of 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 is more than 2% of the length of the first alloy layer, not only the reliable fixation of the bonding material to the metal inner core can be realized, but also the reliable connection of the bonding material to the electrode can be realized.

[0016] In a second aspect of the present application, a photovoltaic system is provided, comprising: a plurality of any of the above photovoltaic modules; each of the photovoltaic modules is arranged in an array in the photovoltaic system.

[0017] The photovoltaic module and the photovoltaic system have the same or similar beneficial effects, and to avoid repetition, they will not be described here. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the description of the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0019] Figure 1 A front view structural schematic diagram of a photovoltaic module in an embodiment of the present application is shown;

[0020] Figure 2 A first partial SEM schematic diagram of a photovoltaic module in an embodiment of the present application is shown;

[0021] Figure 3 A second partial SEM schematic diagram of a photovoltaic module in an embodiment of the present application is shown;

[0022] Figure 4 A distribution structure schematic diagram of an electrical connector and a bonding material in an embodiment of the present application is shown;

[0023] Figure 5 A third partial SEM schematic diagram of a photovoltaic module in an embodiment of the present application is shown;

[0024] Figure 6A connection diagram of an electrical connector and a cell in an embodiment of the present application is shown.

[0025] Figure 7 A structure diagram of a second alloy layer in another photovoltaic module in an embodiment of the present application is shown.

[0026] Explanation of figure numbers:

[0027] 1-cell, 11-electrode, 111-connection part, 2-electrical connector, 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

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0029] In the related art, for the electrical connection in a photovoltaic module, mainly only attention is paid to whether an alloy is formed between an electrode and an electrical connector. However, the formation of an alloy between a metal inner core of the electrical connector and a 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 inner core of the electrical connector and the bonding material. The first alloy layer, as an electrical and mechanical connector between the metal inner core and the bonding material, can improve the current collection effect and improve the connection reliability and stability of the photovoltaic module during years of service.

[0030] In addition, in the related art, for the electrical connection in a photovoltaic module, mainly attention is paid to the size of the pulling force value, and it is considered that the greater the pulling force value, the better the electrical connection quality. However, sometimes the pulling force value of the connection meets the requirements, but there are still phenomena such as excessive connection or virtual connection that affect the connection quality. In the present application, the electrical connection quality of the photovoltaic module is researched from a more subtle and more comprehensive perspective, so as to ensure a suitable and reliable fixed connection effect.

[0031] The present application 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 for collecting and leading out current. The electrical connector 2 has a metal inner core 21 for electrically connecting the electrodes 11 of two adjacent cells 1 through a bonding material 22.

[0032] The bonding material 22 can be a bonding material attached to the electrical connecting piece 2, or can be a bonding material separately arranged from the electrical connecting piece 2, for example, the bonding material 22 is a separately arranged tin paste, tin alloy material, etc. No specific limitation is made thereto. For example, Figure 1 In the embodiment, the bonding material 22 can be a bonding material attached to the electrical connecting piece 2. The bonding material 22 can also be a combination of the bonding material attached to the electrical connecting piece 2 and the separately arranged tin paste, etc.

[0033] It should be noted that the main component of the bonding material includes tin, on the one hand, the melting point of tin is relatively low, the energy consumption of the interconnection process is low, the connection process is simple, and on the other hand, tin has good fluidity in the molten state, and can easily form good coating or covering with the metal inner core of the common electrical connecting piece, such as copper core, etc.

[0034] The first alloy layer 31 is formed between the bonding material 22 and the metal inner core 21, and the first alloy layer 31 can be an intermetallic compound (IMC), which serves as an electrical and mechanical connector of the bonding material 22 and the metal inner 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 the adjacent two battery pieces by using the electrical connecting piece 2 mainly includes surface wetting, interatomic diffusion, dissolution, metallurgical bonding, etc., which is a very complex chemical reaction, and whether a good IMC can be formed is a key indicator of the connection quality. Referring to Figure 6 The electrical connecting piece 2 specifically electrically connects the positive electrode of one battery piece and the negative electrode of another battery piece to realize interconnection.

[0035] It should be noted that the first alloy layer and the second alloy layer described below can be a relatively stable chemical bond formed between two substances, which exists as an electrical and mechanical connector to conduct and transmit current.

[0036] The application mainly solves the connection reliability problem of the photovoltaic module from the following four aspects. The first aspect is to improve and ensure the connection reliability of the photovoltaic module by improving the characteristics of the first alloy layer. The second aspect is to improve the connection reliability of the photovoltaic module by improving the second alloy layer 32 formed between the electrode 11 and the bonding material 22. The third aspect is to improve the connection reliability of the photovoltaic module by improving the characteristics of the connection point between the electrical connector 2 and the electrode 11. The fourth aspect is to improve the connection reliability of the photovoltaic module by controlling the topographic characteristics of the electrical connector 2 and the electrode 11. Through the above four aspects of research, the connection reliability of the photovoltaic module is significantly improved, the risk of the electrical connector separating from the cell during the service of the photovoltaic module for many years is reduced, and the quality and reliability of the photovoltaic module are improved. It should be understood that the improvement of the above four aspects can achieve the improvement of the connection reliability of the electrical connector and the cell by adopting any scheme, and of course multiple schemes can be superimposed to achieve better results. The following will introduce the improvement of the photovoltaic module from the first aspect to the fourth aspect one by one.

[0037] The following will introduce the main content of the first aspect in detail. Figure 2 、 Figure 3 are the first cross-sectional local SEM (scanning electron microscope) images in 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 1 In the first cross section, the first alloy layer 31 covers more than 80% of the outline of the metal inner core 21. That is, in the first cross section, the first alloy layer 31 covers most of the outline of the metal inner core 21, and the first alloy layer formed between the bonding material 22 and the metal inner core 21 covers the metal inner core 21 completely. On the one hand, covering the metal inner core to a large extent can ensure that the connection between the metal inner core 21 and the bonding material 22 is highly reliable, and reduce the risk of the metal inner core being pulled out of the bonding material due to tension and the like. On the other hand, it can ensure that most of the surface of the metal inner core is covered by the first alloy layer and is in a non-exposed state, thereby reducing the risk of the metal inner core being eroded by water vapor and oxidized due to the exposure of the metal inner core during the long-term service of the photovoltaic module, and further ensuring the electrical conductivity and physical and chemical properties of the metal inner core to be stable. Therefore, when the first alloy layer covers more of the metal inner core, i.e., more than 80%, the electrical connection reliability, electrical conductivity, and structural stability of the photovoltaic module are better.

[0038] For example, in the first cross section, the first alloy layer 31 can cover 80%, 83%, 85%, 89%, 90%, 92%, 95%, 96%, 98.3%, 99%, 99.2%, 99.7%, or 100% of the outline of the metal inner core 21.

[0039] In some embodiments, in the first cross section, the first alloy layer 31 covers more than 90% of the contour line of the metal inner core 21. Here, it is mainly said that the first alloy layer 31 covers more of the contour line of the metal inner core 21, the first alloy layer formed between the bonding material 22 and the metal inner core 21 covers the metal inner core 21 more completely, the connection between the metal inner core 21 and the bonding material 22 is more reliable, and the risk of exposure of the metal inner core 21 can be further reduced, thereby improving the electrical connection reliability, electrical conductivity, and structural stability of the photovoltaic module.

[0040] For example, in the first cross section, the first alloy layer 31 can 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 inner core 21.

[0041] 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 circumference of the contour line of the metal inner core 21 is (0.8 to 5):1. At this time, it can be ensured that 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 sufficient thickness and can have a good fixing and covering effect.

[0042] The circumference of the outer contour of the first alloy layer 31 refers to the total length of the outer contour line of the first alloy layer 31. For example, if the outer contour of the first alloy layer 31 is arc-shaped or circular, the length of the outer contour is the circumference of the sector or the circumference of the circle. For example, if the outer contour of the first alloy layer 31 is circular with a radius of r, the length of the outer contour is 2πr. The circumference of the contour line of the metal inner core 21 refers to the total length of the contour line of the metal inner core 21 in the first cross section. For example, if the metal inner core 21 is a circular metal inner core with a radius of x, the circumference of the contour line is 2πx. For another example, if the metal inner core 21 is a flat metal inner core, the contour line thereof is a rectangle in the first cross section, the lengths of the two mutually 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 length direction of the flat metal inner core, the width direction of the flat metal inner core, and the thickness direction of the flat metal inner core are mutually perpendicular, and the circumference of the contour line is 2a+2b. When the outer contour of the first alloy layer is irregular, the circumference is the length of the irregular contour line.

[0043] 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 inner 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.

[0044] In some embodiments, the thickness of the first alloy layer 31 is 0.5 μm to 4 μm, and the direction in which the thickness of the first alloy layer 31 is located is indicated by the outer contour of the first alloy layer 31 to the inner contour. When the first alloy layer 31 is in this thickness range, the thickness of the first alloy layer that clads the metal inner core is more appropriate, the mechanical connection strength of the first alloy layer is better, and the physicochemical properties are more stable. More specifically, if the thickness of the first alloy layer 31 is less than 0.5 μm, a firm and reliable mechanical connection is not formed between the metal inner core 21 and the bonding material 22, and 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 prone to breakage. It should be noted that for one metal inner core 21, the thickness of the first alloy layer 31 at different positions can not be exactly the same, and the thickness of the first alloy layer here can refer to the maximum thickness in a certain region of the first alloy layer 31.

[0045] For example, the thickness of the first alloy layer 31 can 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, 4 μm.

[0046] In some embodiments, referring to Figure 3 , the first alloy layer 31 surrounds the metal inner core 21 in a wavy shape. The main component of the first alloy layer includes tin-copper intermetallic compound. Specifically, the main component of the bonding material is tin and other metals, and the main metal component in the bonding material is unevenly distributed. The wavy shape is more likely to form continuous IMC, further ensuring maximum cladding of the metal inner core 21, and further improving the connection reliability of the metal inner core. The main component of the first alloy layer is determined by the bonding material and the metal inner core. Different bonding materials matched with different metal inner cores can form first alloy layers of different materials. When the main component of the first alloy layer includes tin-copper intermetallic compound (such as Cu6Sn5), the material properties are relatively stable, and the materials are easy to combine with each other, thereby making the photovoltaic module produced have good electrical connection effect.

[0047] In some embodiments, referring to Figure 3In the first cross section, the first alloy layer 31 comprises an inner contour and an outer contour, and the inner contour and the outer contour are as described above. The metal inner core 21 is a circular metal inner core, and the ratio of the length 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), where x is the radius of the metal inner core in millimeters. In actual production, the generation of the first alloy layer, i.e., the length of the outer contour of the first alloy layer, can be appropriately controlled according to the size of the circular metal inner core, so as to achieve a better connection, fixation and covering effect.

[0048] For example, the metal inner core 21 is a circular metal inner core, and when the radius x of the metal inner core is 1 mm, the ratio of the length 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.

[0049] The metal inner core 21 is a flat metal inner core, and the ratio of the length 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), where a is the width of the metal inner core and b is the thickness of the metal inner core, and both a and b are in millimeters. In actual production, the generation of the first alloy layer, such as the thickness, covering degree, etc., i.e., the length of the outer contour of the first alloy layer, can be controlled according to the width and thickness of the flat metal inner core, so as to achieve a better connection, fixation and covering effect. For example, 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.

[0050] For example, the metal inner core 21 is a flat metal inner core, and when the width a of the metal inner core is 2 mm and the thickness of the metal inner core is 4 mm, the ratio of the length 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 12:22.5 to 12:96.

[0051] In some embodiments, the metal inner core 21 can be a triangular metal inner core, and the ratio of the length 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 lengths of the sides of the cross section of the metal inner core, and the units are mm. The triangular metal inner core refers to the cross-sectional shape of the metal inner core being triangular, such as isosceles triangle, non-isosceles triangle, etc. For example, 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 length 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 5:6.5 to 5:17. At this time, the coverage degree and the coverage thickness of the important connection layer first alloy layer can be adjusted by adjusting the interconnection process according to the size of the metal inner core.

[0052] 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 cross-sectional area of the metal inner core 21 is large, the resistivity is small, and the current transmission effect is good.

[0053] For example, in the first cross section, the cross-sectional area of the metal inner core 21 can be 0.00785 mm 2 , 0.0085 mm 2 , 0.009 mm 2 , 0.0095 mm 2 , 0.01 mm 2 , 0.015 mm 2 , 0.017 mm 2 , 0.019 mm 2 , 0.02 mm 2 , 0.025 mm 2 , 0.027 mm 2 , or 0.03 mm 2 .

[0054] In some embodiments, the metal inner core 21 includes a copper core. The metal inner core not only has low cost but also has good conductivity. For example, the metal inner core 21 is a circular copper core, and the diameter of the copper core is 0.1 mm to 0.5 mm.

[0055] In some embodiments, in the first cross section, the bonding material 22 covers more than 80% of the profile line of the metal inner core 21. In this first cross section, the bonding material 22 covers more of the metal inner core 21, on the one hand, the bonding material has a larger contact area with the metal inner core, 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 more than the center, which can play a good 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 or even covers the top, and the flat metal inner core is difficult to come out of the bonding material, thereby achieving a good connection effect. Even if the first alloy layer fails, the metal inner core can still be fixed by the bonding material.

[0056] For example, in the first cross section, the bonding material 22 can cover 80%, 83%, 87%, 85%, 90%, 92.5%, 93%, 95%, 96%, 97%, 98%, 99%, or 100% of the profile line of the metal inner core 21.

[0057] In some embodiments, as shown in Figure 2 In some embodiments, in the first cross section, the width of the bonding material 22 in contact with the electrode 11 and the battery piece is greater than the width of the metal inner core 21. The width direction is perpendicular to the length direction of the electrical connector. The upper end of the bonding material is in contact with the metal inner core, and the lower end is in contact with the electrode. When the lower end of the bonding material has a large width, the bonding material that has fixed the metal inner core has a large contact area on the battery piece, which is conducive to forming a high-quality alloy layer with a large area between the electrode and the bonding material. In addition, the structure of the lower end being larger than the upper end is conducive to the fixation of the bonding material and the metal inner core on the surface of the battery piece, which can improve the connection reliability of the photovoltaic module.

[0058] In some embodiments, the bonding material is a single bonding material, that is, the source of the bonding material is single. It can be the bonding material wrapped outside the metal inner core of the electrical connector 2, or the bonding material separately arranged between the metal inner core and the electrode.

[0059] 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 inner core, and the second bonding material 222 covers the bottom and at least part of the side of the first bonding material, as shown in Figure 4 The second bonding material is arranged in a process independent of the first bonding material, such as tin paste. The source of the bonding material is flexible and suitable for various scenarios. The second bonding material can supplement the first bonding material and enhance the bonding strength between the electrode and the metal inner core. It can also increase the contact area between the first bonding material and the battery piece to increase the area of the second alloy layer. Figure 4It can be seen that due to the arrangement of the second bonding material, the volume of the bonding material is increased, and the wrapping and fixing effect on the side surface of the metal inner core is obviously enhanced.

[0060] The main content of the second layer will be described in detail below. Referring to Figure 1 , a second alloy layer 32 is formed between the electrode 11 and the bonding material 22, which serves as an electrical and mechanical connector between the electrode 11 and the bonding material 22, reliably and firmly connecting the electrode 11 and the bonding material 22, and achieving reliable and effective collection of current.

[0061] 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., so the second alloy layer 32 includes silver-tin intermetallic compounds (such as Ag3Sn) or copper-tin intermetallic compounds, tin-nickel intermetallic compounds. The above electrode has good electrical conductivity, and the above second alloy layer 32 has low resistivity and good electrical conductivity. The mass ratio of tin and silver in the silver-tin intermetallic compound is not specifically limited. The mass ratio of copper and tin in the copper-tin intermetallic compound is not specifically limited. The mass ratio of nickel and tin in the tin-nickel intermetallic compound is not specifically limited.

[0062] In some embodiments, referring to Figure 1The total length of the second alloy layer at the position of the electrical connecting member 2 on one surface of one cell 1 is L1. The surface here refers to the surface of the cell on which the electrode 11 is arranged, which can refer to the back surface only, or can refer to the light-receiving surface and the back surface. During normal operation of the cell, the main light-receiving surface is the light-receiving surface, and the back surface is opposite the light-receiving surface. The electrical connecting member can be a ribbon, or can be a conductive layer on a conductive back plate that connects adjacent cells. The length of the part of one electrical connecting member 2 on the surface of the cell is L2, and the length is in a direction parallel to the extension direction of the electrical connecting member 2. Generally, one electrical connecting member 2 needs to extend from the head of one cell to the tail of the adjacent cell across the gap between the two cells. 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 one electrical connecting member on one surface of one cell 1 is greater than or equal to 2.1% of the length L2 of the part of the electrical connecting member on the surface. When the total length L1 of the second alloy layer on one surface of one cell 1, that is, the length of the part of the electrical connecting member on which the electrode and the electrical connecting member are connected by alloying, is greater than 2.1% of the length of the electrical connecting member, on the one hand, it can ensure that the current has a sufficient collection and transmission channel, and the current collection effect is good; on the other hand, the electrode and the electrical connecting member have sufficient alloy connection to ensure the reliability of the electrical connecting member. When the ratio of L1 to L2 is less than 2.1%, the current collection and transmission channel is not sufficient, and the current collection has a certain loss, which reduces the performance of the photovoltaic module. It should be noted that the ratio of L1 to L2 is greater than or equal to 2.1% for both cells with bus bars and cells without bus bars. For example, the ratio of L1 to L2 can be 2.1%, 2.3%, 2.5%, 2.2%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, or 3.5%.

[0063] Optionally, the second alloy layer at the position of one electrical connecting member 2 on one surface of one cell 1 can be arranged in multiple parts on the cell, specifically in more than 5 connection points. For example, 6, 7, 8, 10, or even 20 connection points. The spacing between the connection points is less than 5 mm. For example, the spacing between the connection points is 5 mm, 4 mm, 3 mm, 2 mm, 1 mm, or 0.5 mm. At this time, the second alloy layer of one electrical connecting member on the cell is not designed to be concentrated, but is distributed in multiple points and is relatively uniform. This design makes the points of the electrical connecting member where the current converges more dispersed and more uniform, which is conducive to rapid current collection and reduces current loss. Moreover, compared to being connected and fixed at one point, the multiple-point and relatively uniform fixed connection has better fixing effect and is less likely to have problems such as local disconnection and warping of the electrical connecting line.

[0064] It should be noted that in the case of a plurality of electrical connections on one surface of a battery piece, one of the electrical connections can meet the above design to achieve a certain effect. L1 and L2 are the total length of the second alloy layer on one surface of the battery piece, one electrical connection and the second alloy layer below it. The second alloy layer is arranged in an array on one surface of the battery piece.

[0065] In some embodiments, the battery piece includes opposite first and second surfaces, one of the first and second surfaces is a light-receiving surface and the other is a light-reflecting surface, and electrodes are provided on both the first and second surfaces, that is, the battery piece is a double-sided electrode battery piece. For the first and second surfaces, the ratio of L1 to L2 is greater than or equal to 2.85%. It should be understood that L1 here is still the total length of the second alloy layer on one surface of the battery piece at an electrical connection position. For the first surface, the ratio of L1 to L2 is greater than or equal to 2.85%. The second surface is similarly provided. For the light-receiving surface and the light-reflecting surface of the double-sided battery piece, the total length of the second alloy layer on both surfaces accounts for more than 2.85%, which can make the current collection on both surfaces more balanced, reduce current loss caused by current mismatch, and also improve the stability and balance of the connection force of the electrical connections on both surfaces, reducing problems such as hidden cracks and broken pieces caused by uneven tension on the two opposite surfaces of the battery piece. It should be noted that for the battery piece, whether it is a battery piece with a busbar or a battery piece without a busbar, the ratio of L1 to L2 is greater than or equal to 2.85%.

[0066] For example, the battery piece includes opposite first and second surfaces, and electrodes are provided on both the first and second surfaces. For the first and second surfaces, the ratio of L1 to L2 can be 2.85%, 2.9%, 2.91%, 2.92%, 2.98%, 3%, 3.1%, 3.4%, 3.2%, or 3.5%. For another example, the battery piece includes opposite first and second surfaces, and electrodes are provided on both the first and second surfaces. For the first and second surfaces, for a battery piece with a busbar, L1 can be about 7.12 mm, and for a battery piece without a busbar, L1 can be about 2.997 mm, and L2 is about 80 mm to 105 mm.

[0067] The double-sided battery piece here can be a TOPCon (passivated contact) battery piece, a heterojunction battery piece, etc., and the specific type of battery piece is not limited.

[0068] In some embodiments, the battery piece includes opposite first and second surfaces, one of the first and second surfaces is a light-receiving surface and the other is a light-irradiating surface, and electrodes are provided only on the first surface. In this case, the first surface can be the light-irradiating surface, that is, the battery piece is a back contact or single-sided battery piece. For the first surface, the ratio of L1 to L2 is greater than or equal to 4.2%. For a single-sided battery piece or a back contact battery piece in which electrodes are provided on the light-irradiating surface, the electrodes and the electrical connectors connected to the electrodes are located on one side surface of the battery piece. In this case, the area of the second alloy layer corresponding to one electrical connector is appropriately increased, that is, the alloy connection area between the electrode and the electrical connector is appropriately increased, so that the stress and the current concentration point can be dispersed, on the one hand, the current collection and transmission effect is improved, the connection stability is improved, on the other hand, the force between the electrical connector and the battery piece is more uniform and dispersed, the risk of battery piece cracking and fragmentation is reduced, and the current collection efficiency is improved and the loss is reduced by the multi-point and large-area current concentration.

[0069] It should be noted that, in this case, the ratio of L1 to L2 is greater than or equal to 4.2% for both the battery piece with bus bars and the battery piece without bus bars. For example, the battery piece includes opposite first and second surfaces, and electrodes are provided only 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%, or 4.995%. For another example, the battery piece includes opposite first and second surfaces, and electrodes are provided only on the first surface. For the first surface, for the battery piece with bus bars, L1 can be about 11 mm, and for the battery piece without bus bars, L1 can be about 2.16 mm to 5.4 mm or about 10.48 mm, and L2 is about 80 mm to 105 mm.

[0070] In this case, the single-sided battery piece or the back contact battery piece can be a back contact heterojunction battery piece, an interdigital back contact battery piece, a back contact battery piece with a tunneling passivation layer, etc. The specific type of battery piece is not limited.

[0071] In some embodiments, the electrode 11 comprises a current collecting electrode, the extending direction of the current collecting electrode is parallel to the extending direction of the electrical connector. The current collecting electrode is arranged corresponding to the N-type doped layer and the P-type doped layer. There is generally no busbar in the cell, and the electrical connector is directly arranged on the current collecting electrode, so that the ratio of L1 to L2 is greater than or equal to 60%. That is, the total length of the second alloy layer at the position of one electrical connector on one surface of the cell is L1, the length of the part of the 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 the electrical connector for current collection and fixed connection is greatly increased, and better current collection effect and electrical connection reliability can be obtained.

[0072] Further, the electrode 11 comprises a current collecting electrode, the extending direction of the current collecting electrode is parallel to the extending direction of the electrical connector, and the ratio of L1 to L2 can be 80% to 90%. For example, the electrode 11 comprises a current collecting electrode, the extending direction of the current collecting electrode is parallel to the extending direction of the electrical connector, and the ratio of L1 to L2 can be 60%, 65%, 70%, 72%, 75%, 80%, 83%, 85%, 89%, or 90%. At this time, the current collection and electrical connection effect of the electrical connector can be further improved.

[0073] In some embodiments, on one surface of one cell 1: the total length of the second alloy layer 32 at the position of one electrical connector 2 is L1. On one surface of one cell 1: the total length of the first alloy layer at the position of one electrical connector 2 is L3, and the direction of the length is parallel to the extending direction of the electrical connector 2. Here, the one surface is also the light-receiving surface or the back surface of the cell. The ratio of L1 to L3 is greater than or equal to 2%, the first alloy layer is mainly used to realize the reliable connection of the metal inner core and the bonding material, and the second alloy layer is mainly used to realize the reliable connection of 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 the reliable fixation of the bonding material to the metal inner core can be realized, but also the reliable connection of the bonding material to the electrode can be realized. More specifically, when the ratio of L1 to L3 is less than 2%, the current collection and transmission channel is not enough, there is a certain loss in current collection, and the performance of the photovoltaic module is reduced.

[0074] It should be noted that the ratio of L1 to L3 is greater than or equal to 2% for the battery piece with busbar or without busbar. 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%, 3.4%. It should be noted that at least one of the plurality of electrical connectors on one surface of the battery piece is designed according to the above design. Of course, the more or all of the electrical connectors are designed according to the above design, and the electrical connection reliability and current transmission effect of the photovoltaic module are better.

[0075] In some embodiments, one electrical connector 2 connects two adjacent battery pieces 1, and the electrical connector has a plurality of second alloy layers 32 between the two battery pieces 1. The length of the second alloy layer at the head and / or tail along the length direction of the electrical connector 2 is greater than the length of the second alloy layer at the middle. The second alloy layer at the head and / or tail along the length direction of the electrical connector 2 is mainly the second alloy layer at the end of the electrical connector. The end position is more prone to bending, warping, etc. compared with the second alloy layer at the middle. Therefore, the connection quality of the second alloy layer at the end has a greater impact on the electrical connector and the two battery pieces 1. In this application, the length of the second alloy layer at the end position is longer, and the second alloy layer at the end position can be compatible with the possible bending, warping, etc. Under the above possible adverse effects, it can still maintain good conductive effect. The number of second alloy layers contained in one electrical connector is not limited.

[0076] Optionally, the end position of the electrical connector on the battery piece is provided with a connecting portion, and the width of the connecting portion is greater than the width of the current collecting electrode. The end of the electrical connector exceeds the center of the connecting portion. At this time, the contact length of the end of the electrical connector and the connecting portion is larger, which is easy to realize reliable electrical connection and avoid the end of the electrical connector from being raised or separated.

[0077] The third layer will be introduced in detail below. At one 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 inner core 21. 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 sheet. At a single connection point, the second alloy layer 32 has a larger width, which can achieve a larger electrical connection range between the connection point and the electrical connector 2, and the connection is more stable and reliable. Specifically, the electrode 1 can have multiple connection points, for example, 7 to 20 connection points on one electrode 1, and the second alloy layer is formed between the bonding material at each connection point of the electrode. If the width of the second alloy layer is less than 0.3 times the width of the metal inner core, the coverage of the second alloy layer is relatively small, and in the case of bending of the photovoltaic module, the second alloy layer at the connection point is prone to separation.

[0078] For example, at one 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 inner core 21.

[0079] In some embodiments, referring to 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 approximately rectangular, square, or rectangular with chamfered corners, etc. Compared with a circular electrical connector, the flat electrical connector mainly contacts the surface of the electrode, and the contact area is larger than the surface-to-line contact between the electrode and the circular electrical connector, and the interconnection is more stable and reliable. In addition, 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 battery sheet cracking and cracking.

[0080] In some embodiments, the electrical connector 2 is a flat electrical connector, and the ratio of the width of the metal inner core 21 to the width of the second alloy layer 32 at one connection point of the electrical connector 2 and the electrode 1 is 1:(1-4), that is, for the flat electrical connector, the width of the second alloy layer 32 is greater than the width of the metal inner core at one connection point, so that the second alloy layer on the lower side is wider than the metal inner core on the upper side, and the second alloy layer can well fix the metal inner core. In addition, the contact position of the bonding material and the electrode is usually connected weakly, and cracking phenomenon is prone to occur. When the width of the second alloy layer is greater than the width of the metal inner core, the connection width is larger, and the corresponding connection strength is larger, and the second alloy layer is more stable from the metal inner core to the bonding material and the electrode. In addition, the width of the second alloy layer is less than 4 times the width of the metal inner core, which can appropriately reduce the amount and coverage of the bonding material, avoid high material cost, and avoid the influence of the bonding material on 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 piece 1. The width of the second alloy layer can be measured 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 qualified and whether the electrical connection at the connection point is qualified.

[0081] For example, the electrical connector 2 is a flat electrical connector, and the ratio of the width of the metal inner core 21 to the width of the second alloy layer 32 at one connection point of the electrical connector 2 and the electrode 1 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.

[0082] In some embodiments, referring to Figure 5 , the electrical connector is a circular electrical connector, and the ratio of the diameter of the metal inner core 21 to the width of the second alloy layer 32 at one connection point of the electrical connector 2 and the electrode 1 is 1:(0.3-3). 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 piece 1. At the single connection point, since the metal inner core 21 is circular, the bonding material can better wrap and fix the metal inner core in a shell shape, and therefore the width of the second alloy layer is greater than 0.3 times the width of the metal inner core, that is, reliable connection can be achieved, and the requirements for service of the photovoltaic module can be met. Moreover, the ratio of the width of the second alloy layer 32 at this time is more appropriate, and a good balance between cost and conductivity effect is achieved.

[0083] For example, the electrical connector is a round electrical connector, and at the connecting point between the electrical connector 2 and the electrode 1, the ratio of the diameter of the metal inner 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, and the like.

[0084] In some embodiments, at the connecting 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 in which the length of the second alloy layer 32 is located is parallel to the extension direction of the electrical connector 2. At the single connecting point, the length of the second alloy layer is large, the connection between the connecting point and the electrical connector is firm and reliable, and the connection effect of the photovoltaic module is excellent.

[0085] For example, at the connecting point between the electrical connector 2 and the electrode 1, the length of the second alloy layer 32 can be 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 90 μm, 100 μm, 200 μm, 500 μm, 800 μm, 1000 μm, 1500 μm, 2000 μm, and the like.

[0086] The second alloy layer 32 is laid on the cell sheet 1, and the second alloy layer 32 is continuously and wavelike distributed. The second alloy layer 32 is mainly an alloy formed by combining the material and the electrode, and the main component of the combined material is mainly tin, which is unevenly distributed, and the wavelike shape is more likely to form continuous IMC, which further ensures complete wrapping of the metal inner core and the electrode and improves the reliability of the electrical connection. Moreover, the wavelike shape can also disperse stress and avoid stress concentration. The state of the second alloy layer 32 is usually not wrapped or surrounded around the electrode, so that no matter what shape the metal inner core or the electrical connector is, it forms a surface-to-surface contact with the electrode, the contact area is larger, the bonding force is greater, and the connection is more reliable. In the wavelike second alloy layer 32, the distance between the trough and the peak can be 0.5 μm to 2 μm, the thickness of the second alloy layer 32 is relatively appropriate, the electrical conductivity is good, and the second alloy layer is not too thick, because the second alloy layer is too thick and is prone to brittle fracture.

[0087] 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 cell sheet. The thickness of the second alloy layer is relatively appropriate, which not only can ensure the connection quality and avoid too little IMC and substandard electrical connection, but also can avoid too thick IMC and brittle fracture, thereby improving the connection reliability of the electrical connection and the cell sheet.

[0088] For example, the thickness of the second alloy layer 32 can 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, 5 μm.

[0089] In some embodiments, the second alloy layer 32 comprises 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 the bonding material and the electrode material, and different selections of the bonding material and the electrode material can form second alloy layers of different materials. When the second alloy layer comprises a silver-tin intermetallic compound or a copper-tin intermetallic compound or a nickel-tin intermetallic compound, the second alloy layer of such material is stable in properties, has good electrical conductivity, has strong connection reliability, and is easy to implement in the process. The mass ratio of tin to silver in the silver-tin intermetallic compound is not specifically limited. The mass ratio of copper to tin in the copper-tin intermetallic compound is not specifically limited. The mass ratio of nickel to tin in the nickel-tin intermetallic compound is not specifically limited.

[0090] In some embodiments, the plane perpendicular to the thickness direction Q of the battery piece 1 is a first plane, the first plane is parallel to the extension direction of the electrical connector, and on the same first plane: the first projection of the second alloy layer 32 intersects the second projection of the metal inner core 21, and the proportion of the intersecting 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 proportion of the intersecting area to the area of the second projection of the metal inner core 21 is relatively large, which can avoid that the electrical connector is set too much, and reduce the risk of being pulled off. More specifically, during the process of forming the electrical connection, the electrical connector can be slightly offset, and can not be located at the center of the connection point of the electrode. Due to the leveling of the bonding material, the second alloy layer is usually located at the center of the connection point of the electrode. The metal inner core of the electrical connector can be offset. From the top view, the metal inner core and the second alloy layer can not be 100% overlapped. The circular electrical connector can roll, and the alignment of the flat electrical connector can have a precision error. However, in general, the connection point of the electrode is fixed, so the position of the second alloy layer is approximately fixed or determined. The position of the electrical connector will be offset. The present application limits the offset of the electrical connector to be small, further improves the connection effect, and reduces the risk of being pulled off.

[0091] For example, the plane perpendicular to the thickness direction Q of the battery piece 1 is a first plane, the first plane is parallel to the extension direction of the electrical connector, and on the same first plane: the first projection of the second alloy layer 32 intersects the second projection of the metal inner core 21, and the proportion of the intersecting area to the area of the second projection can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%.

[0092] In some embodiments, the battery piece 1 is provided with a connecting part, which can be a thickened section on the pad or current collecting electrode, and the connecting part is fixed and electrically connected with the electrode 1 through the bonding material 21. On the battery piece 1, the width of the connecting part is greater than or equal to the width of the electrode, the width of the connecting part is relatively large, the connecting area of the connecting part with the bonding material is relatively large, so that the bonding material has a larger adhesion area on the battery piece, 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 avoid the overflow of the bonding material out of the connecting part.

[0093] In some embodiments, the surface of the connecting part close to the electrical connector 2 is a third surface, and the third surface is the surface of the connecting part away from the battery piece. The second alloy layer 32 covers at least 20% of the third surface, and the second alloy layer at most exceeds 20% of the third surface. On the one hand, the second alloy layer covers a relatively large third surface, which ensures the electrical connection reliability. On the other hand, the part of the second alloy layer exceeding the connecting part has a relatively small short circuit risk. Specifically, when the main component of the bonding material includes tin, the connecting part has a certain adhesion effect on the tin inside the bonding material, which further avoids the overflow of the bonding material out of the connecting part.

[0094] In some embodiments, referring to Figure 6 one electrical connector 2 connects two adjacent battery pieces 1, Figure 6 In some embodiments, referring to the black dot 111 is a schematic of the connecting part, the left battery piece 1 can be a previous battery piece, and the right battery piece 1 can be a next battery piece. The length between the first position of the tail connecting part of the previous battery piece and the second position of the head connecting part of the adjacent next battery piece 1 is L4, and the distance between the adjacent connecting parts 111 on one battery piece 1 is L5. The ratio of L5 to L4 is 1:(0.8-1.5). The positions on one electrical connector connected with each connecting part 111 are each force applying point, and the force applying points are relatively uniformly distributed on one electrical connector, that is, the shear force received by each IMC is basically uniform, which ensures the reliability of the IMC and avoids failure. It should be noted that the number of connecting parts provided on one battery piece 1 is not limited.

[0095] For example, one electrical connector 2 connects two adjacent battery pieces 1, and the length between the first position of the tail connecting part of the previous battery piece and the second position of the head connecting part of the adjacent next battery piece on one electrical connector 2 is L4. The distance between the adjacent connecting parts 111 on one battery piece 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.

[0096] In some embodiments, the distance between the centers of the adjacent connecting portions on the same side of the battery piece 1 in the direction perpendicular to both the extension direction of the electrical connector 2 and the thickness direction Q of the battery piece is less than or equal to 2 mm, that is, the centers of the adjacent connecting portions are as collinear as possible in the direction perpendicular to both the length direction of the electrical connector and the direction Q, and the force acting on the electrical connector is more uniform on the entire electrical connector, and the connection is more reliable. That is, the alignment error between the adjacent connecting portions in the direction perpendicular to both the extension direction of the electrical connector 2 and the thickness direction Q of the battery piece 1 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 connecting portions, that is, the degree of twisting of the entire electrical connector is small, the shear force introduced into the electrical connector is small, and the shear force acting on the electrical connector is small on the entire electrical connector, and the connection is more reliable.

[0097] For example, the distance between the centers of the adjacent connecting portions on the same side of the battery piece 1 in the direction perpendicular to both the extension direction of the electrical connector 2 and the thickness direction Q of the battery piece can be 2 mm, 1.8 mm, 1.5 mm, 1.3 mm, 1.1 mm, 1 mm, 0.9 mm, 0.8 mm, 0.5 mm, 0.4 mm, 0.3 mm, 0.2 mm, 0.1 mm, 0.05 mm, 0.01 mm, 0, etc.

[0098] In some embodiments, at least two sizes of connecting portions are included on the same battery piece 1, that is, there are both large connecting portions and small connecting portions on the same battery piece. The large connecting portions can improve the current carrying capacity, enhance the mechanical connection strength, and improve the connection reliability. The small connecting portions can reduce shading and save space. Therefore, the photovoltaic module of the present application not only ensures the contact area and the IMC area, has good connection reliability, and has low resistance and less shading. It should be noted that the large connecting portions can be located at the edge position of the battery piece, and the small connecting portions are located inside the large connecting portions. The large connecting portions located at the edge position of the battery piece can improve the current collection effect at the edge position of the battery piece.

[0099] The main content of the fourth aspect will be described in detail below. The second cross section in 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, the connecting portion is referred to as a connecting portion in the first cross section or the second cross section. Figure 7The second alloy layer 32 comprises discrete second alloy points 321, which can uniformly bear the connecting force and can improve the reliability and stability of the connection. The electrode herein can be a low-temperature electrode, and the sintering temperature of the low-temperature electrode is lower than that of a high-temperature electrode. The main material of the low-temperature electrode can be selected from the group consisting of micro-nano silver material, micro-nano silver-coated copper material, nano silver material, micro copper material, nano copper material and the like. The above-mentioned materials have good conductivity and good adhesive bonding force. More specifically, since the low-temperature electrode paste is mainly composed of micro-spherical metal particles and microparticle flaky metal bonded by an organic substance, the surface of the low-temperature silver paste after solidification is uneven and forms a "concave-convex" uneven shape, and after forming the electrode, the metal groups in the electrode are relatively dispersed. In this case, the discrete second alloy points are beneficial to the formation of sufficient connecting alloy 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 not only can realize stress dispersion, but also can realize reliable electrical connection between the electrode and the bonding material through the second alloy points. It should be noted that there is still a continuous second alloy in the second alloy layer.

[0100] In some embodiments, the length of the second alloy points 321 is less than or equal to 2 μm, and the length of the second alloy points 321 is the maximum size of the second alloy points 321 in the aforementioned first cross section or second cross section, that is, the maximum size of the second alloy points 321 does not exceed 2 μm. The size of the second alloy points 321 is small and uniformly distributed, which can further uniformly bear the connecting force and can improve the reliability and stability of the connection.

[0101] For example, the length of the second alloy points 321 can 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, 0.005 μm.

[0102] In some embodiments, for one battery piece 1, the distance between adjacent discrete second alloy points 321 is less than or equal to 1 μm. The distance between adjacent discrete second alloy points 321 is small, and the conductivity effect is good.

[0103] For example, for one battery piece 1, the distance between adjacent discrete second alloy points 321 can 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, 0.005 μm.

[0104] In some embodiments, the adjacent discrete second alloy dots 321 are filled with a bonding material and / or an electrode material. The bonding material and the electrode material have good electrical conductivity, which can improve the current transmission effect. In addition, the bonding material has certain viscosity, which can improve the bonding force.

[0105] In some embodiments, the electrode is printed on the surface of the battery sheet, and the surface of the battery sheet has a textured structure. That is, the electrode with the discrete second alloy dots can be applied to the surface with the textured structure, and the discrete second alloy dots enable the electrode to have good adhesion with the textured structure, better pull-off force, and better electrical connection reliability. It should be noted that the electrode can also be applied to a polished surface, but the connection force between the electrode and the textured structure is greater.

[0106] Figure 1 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. The electrode paste usually contains metal particles and organic matter. During the drying and curing process, the metal particles will aggregate, and the aggregated metal particles can be separated by the above-mentioned organic matter. The aggregated metal particles are the metal clusters herein. The distance between the metal clusters is small, the metal density is high, the electrode has good electrical conductivity, and the current collection effect is good.

[0107] For example, in the first cross section, the distance between the metal clusters in the electrode can 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. The distance refers to the minimum distance between two metal clusters.

[0108] In some embodiments, the connection tension between the high-temperature electrode and the electrical connector in the photovoltaic module of the present application can be greater than or equal to 1.5 N / mm 2 , and the connection tension between the low-temperature electrode and the electrical connector can be greater than or equal to 1.2 N / mm 2 . The difference between the high-temperature electrode and the low-temperature electrode mainly lies in the difference in material composition and the difference in sintering temperature. The sintering temperature of the high-temperature electrode is usually higher than that of the low-temperature electrode, and the high-temperature electrode usually contains glass powder. The lower limit of the connection tension for both the high-temperature electrode and the low-temperature electrode is appropriate, which can not only ensure the connection quality, but also avoid the problem of easy breakage due to excessive connection.

[0109] In some embodiments, one electrical connecting member 2 connects two adjacent battery pieces 1, the distance between the edges of the two adjacent battery pieces in the direction perpendicular to the extension direction of the electrical connecting member 2 and the thickness direction Q of the battery piece 1 is less than or equal to 3 mm, the alignment error between the adjacent battery pieces is small in the direction perpendicular to the extension direction of the electrical connecting member 2 and the thickness direction Q of the battery piece 1, the whole electrical connecting member does not need to be twisted to a large extent to adapt to the alignment error between the battery pieces, that is, the whole electrical connecting member is twisted to a small extent, the shear force brought into the electrical connecting member is small, and then the shear force acting on the whole electrical connecting member is small, and the connection is more reliable.

[0110] For example, one electrical connecting member 2 connects two adjacent battery pieces 1; the distance between the edges of the two adjacent battery pieces in the direction perpendicular to the extension direction of the electrical connecting member 2 and the thickness direction Q of the battery piece 1 can be 3 mm, 2.5 mm, 1 m, 2 m, 1.5 mm, 1.2 mm, 3 mm, 0.9 mm, 0.8 mm, 0.1 mm, 0.01 mm.

[0111] In some embodiments, referring to Figure 6 One electrical connecting member 2 connects two adjacent battery pieces 1, and along the extension direction of the electrical connecting member 2, the electrical connecting member 2 covers 70% to 95% of the length of the battery piece 1, the coverage ratio of one electrical connecting member 2 to the length of the battery piece is more appropriate, which can ensure sufficient electrical connecting area and reliable current transmission, not only reducing the current transmission loss, but also bringing less heat into the battery piece during the electrical connecting process.

[0112] For example, one electrical connecting member 2 connects two adjacent battery pieces 1, and along the extension direction of the electrical connecting member 2, the electrical connecting member 2 covers 70% to 95% of the length of the battery piece 1, the coverage ratio of one electrical connecting member 2 to the length of the battery piece is more appropriate, which can ensure sufficient electrical connecting area and reliable current transmission, not only reducing the current transmission loss, but also bringing less heat into the battery piece during the electrical connecting process.

[0113] In some embodiments, the electrical connecting member mentioned throughout the text can be a solder strip, the main material of the bonding material includes tin, for example, the bonding material is tin paste, tin-lead alloy, tin-lead-bismuth alloy, etc., and the electrical connecting member 2 is electrically connected and fixed with the electrode of the battery piece through a welding process and / or a lamination bonding process. The welding process is to directly weld the electrode of the battery piece and the solder strip together, and the lamination bonding process can be to first fix the solder strip and the electrode of the battery piece, and then realize the electrical connection of the solder strip and the electrode by means of the heat environment in the lamination process. The electrical connecting process is flexible and diverse, and is suitable for various scenes. The welding process here can refer to high-temperature infrared welding or low-temperature infrared welding, etc.

[0114] It should be noted that the above four aspects of the present application are detailed descriptions of the photovoltaic module of the present application from different angles, and the relevant parts of the four aspects can be referred to each other. In order to avoid repetition, the relevant parts are briefly described.

[0115] The present application also provides a photovoltaic system comprising a plurality of arrays of any of the above photovoltaic modules. The form of the photovoltaic system is not specifically limited, for example, the photovoltaic system can exist directly as a building roof, or the photovoltaic system is arranged on a building roof, and other structures of the photovoltaic system are not specifically limited. Compared with the photovoltaic module, the photovoltaic system can further expand the application scenario of the cell sheet.

[0116] The photovoltaic system has the same or similar beneficial effects as any of the above photovoltaic modules, and the relevant parts can be referred to each other. In order to avoid repetition, this place will not be described again.

[0117] It should be noted that in this document, the term "comprising" or "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or apparatus including a series of elements includes not only those elements, but also other elements not explicitly listed, or further includes elements inherent to such a process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus including the element.

[0118] The embodiments of the present application are described above in combination with the drawings, but the present application is not limited to the above specific embodiments. The above specific embodiments are only illustrative, but not restrictive. Those skilled in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, and these are all within the protection of the present application.

Claims

1. A photovoltaic module, characterized by, The battery piece comprises: a battery piece; the battery piece is provided with an electrode; an electrical connector, the electrical connector has a metal inner core; the metal inner core is electrically connected to the electrodes of two adjacent battery pieces by a bonding material; a first alloy layer is formed between the bonding material and the metal inner core; a second alloy layer is formed between the electrode and the bonding material; the total length of the second alloy layer at the position of one of the electrical connectors on one surface of one of the battery pieces is L1; the length of the part of one of the electrical connectors located on the surface of the battery piece 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%; and / or, on one surface of one of the battery pieces: the total length of the first alloy layer is L3; the ratio of L1 to L3 is greater than or equal to 2%.

2. The photovoltaic module of claim 1, wherein, The battery piece comprises: opposite first and second surfaces; the first and second surfaces are both provided with electrodes; for the first and second surfaces, the ratio of L1 to L2 is greater than or equal to 2.85%.

3. The photovoltaic module of claim 1, wherein, The battery piece comprises: opposite first and second surfaces; only the first surface is provided with electrodes; for the first surface, the ratio of L1 to L2 is greater than or equal to 4.2%.

4. The photovoltaic module of claim 1, wherein, The electrode comprises: a current collecting electrode, the extension direction of the current collecting electrode is parallel to the extension direction of the electrical connector; the ratio of L1 to L2 is greater than or equal to 60%.

5. The photovoltaic module according to claim 1, wherein one of the electrical connectors connects two adjacent battery pieces, the electrical connector and the two battery pieces have a plurality of second alloy layers therebetween, 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.

6. The photovoltaic module according to any of claims 1 to 5, characterized in that At a connection point between the electrical connector and one of the electrodes, 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 piece.

7. The photovoltaic module of any of claims 1-5, wherein, In the first cross section or the second cross section, the second alloy layer comprises discrete second alloy points; the first cross section is perpendicular to the extension direction of the electrical connector; the second cross section is parallel to the extension direction of the electrical connector and perpendicular to the first cross section.

8. The photovoltaic module of claim 7, wherein, The length of the second alloy point is less than or equal to 2μm, the length of the second alloy point is the maximum dimension of the second alloy point in the cross section; and / or, the distance between adjacent discrete second alloy points is less than or equal to 1μm.

9. The photovoltaic module of claim 7, wherein, The space between adjacent discrete second alloy points is filled with bonding material or electrode material; and / or, the main material of the electrode is selected from: micron silver material, micron silver-coated copper material, micron copper material, nano silver material, nano copper material.

10. A photovoltaic system characterized by, The photovoltaic system comprises: a plurality of photovoltaic modules according to any one of claims 1 to 9; each of the photovoltaic modules is arranged in an array in the photovoltaic system.

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