Photovoltaic module and photovoltaic system

Abstract

The present application relates to the technical field of photovoltaics. Provided are a photovoltaic module and a photovoltaic system. The photovoltaic module comprises: solar cells, wherein each of the solar cells is provided with an electrode; and an electrical connector, wherein the electrical connector is provided with a metal inner core electrically connected to electrodes of two adjacent solar cells by means of a bonding material, a first alloy layer is formed between the bonding material and the metal inner core, a cross section perpendicular to the direction of length extension 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 a profile line of the metal inner core. The photovoltaic module of the present application not only has reliable connection quality and a good current transmission effect, but also is substantially free of excessive connections, such that the connection reliability and stability of the photovoltaic module during years of service can be improved.

Description

Photovoltaic modules and photovoltaic systems

[0001] This application claims priority to Chinese Patent Application No. 202411495763.8, filed on October 24, 2024, entitled "Photovoltaic Module and Photovoltaic System", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of photovoltaic technology, and in particular to a photovoltaic module and a photovoltaic system. Background Technology

[0003] The process of forming a photovoltaic module involves connecting two adjacent solar cells in series using electrical connectors. The quality of this series connection directly affects the reliability of the photovoltaic module. If the connection is unstable, issues such as loose connections, exposed cells, and short circuits will occur, severely impacting the module's power output and overall performance.

[0004] In existing photovoltaic modules, poor connection reliability can lead to electrical connectors detaching from the cells during years of service, affecting the quality and reliability of the photovoltaic modules.

[0005] Application content

[0006] This application provides a photovoltaic module and a photovoltaic system, which aims to solve the problem of poor connection reliability in existing photovoltaic modules.

[0007] A first aspect of this application provides a photovoltaic module, comprising:

[0008] Battery cell; the battery cell is provided with electrodes;

[0009] An electrical connector having a metal core;

[0010] The metal core is electrically connected to the electrodes of two adjacent battery cells via a bonding material;

[0011] A first alloy layer is formed between the bonding material and the metal core; a second alloy layer is formed between the electrode and the bonding material;

[0012] At one 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 core;

[0013] The width is perpendicular to the extension direction of the electrical connector and also perpendicular to the thickness direction of the battery cell.

[0014] At a single connection point, the second alloy layer has a larger width, which allows for a larger electrical connection amplitude between the connection point and the electrical connector, resulting in a more robust and reliable connection.

[0015] In some possible embodiments, a cross section perpendicular to the length extension direction of the metal core is a first cross section, in which the first alloy layer covers more than 80% of the outline of the metal core.

[0016] In this first cross-section, the first alloy layer covers a greater portion of the outline of the metal core, encompassing most of it. The first alloy layer, forming a relatively complete coverage of the metal core between the bonding material and the metal core, ensures a high degree of reliability in the connection between the metal core and the bonding material, reducing the risk of the metal core detaching from the bonding material due to tensile forces. Furthermore, it ensures that most of the surface of the metal core is covered by the first alloy layer, preventing exposure and reducing the risk of moisture erosion and oxidation of the metal core during the long-term service life of the photovoltaic module. This, in turn, ensures the stability of the metal core's electrical conductivity and physicochemical properties. Therefore, when the first alloy layer covers a significant portion of the metal core (over 80%), the photovoltaic module exhibits better electrical connection reliability, conductivity, and structural stability.

[0017] A second aspect of this application provides a photovoltaic system comprising: an array of any of the aforementioned photovoltaic modules.

[0018] The photovoltaic modules and photovoltaic systems mentioned above have the same or similar beneficial effects, and will not be repeated here to avoid repetition.

[0019] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 shows a front view of a photovoltaic module according to an embodiment of this application;

[0022] Figure 2 shows a first partial SEM schematic diagram of the photovoltaic module in an embodiment of this application;

[0023] Figure 3 shows a second partial SEM schematic diagram of the photovoltaic module in an embodiment of this application;

[0024] Figure 4 shows a schematic diagram of the distribution structure of an electrical connector and bonding material in an embodiment of this application;

[0025] Figure 5 shows a third partial SEM schematic diagram of the photovoltaic module in the embodiment of this application;

[0026] Figure 6 shows a schematic diagram of the connection between an electrical connector and a battery cell in an embodiment of this application;

[0027] Figure 7 shows a schematic diagram of the structure of the second alloy layer in another photovoltaic module according to an embodiment of this application.

[0028] Explanation of the attached figures: 1-Battery cell, 11-Electrode, 111-Connector, 2-Electrical connector, 21-Metal core, 22-Binding material, 221-First bonding material, 222-Second bonding material, 31-First alloy layer, 32-Second alloy layer, 321-Second alloy point. Specific Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] In related technologies, the electrical connection in photovoltaic modules mainly focuses on whether an alloy is formed between the electrodes 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 this 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.

[0031] In other related technologies, the electrical connection in photovoltaic modules mainly focuses on the tensile strength, believing that the greater the tensile strength, the better the electrical connection quality. However, sometimes even if the tensile strength of the connection meets the requirements, there may still be phenomena such as over-connection or loose connection that affect the connection quality. This application studies the electrical connection quality of photovoltaic modules from a more detailed and comprehensive perspective, thereby ensuring a suitable, reliable and fixed connection effect.

[0032] This application provides a photovoltaic module. Referring to FIG1, the photovoltaic module includes: solar cells 1 and electrical connectors 2. The solar cells 1 are provided with electrodes 11 for collecting and discharging current. The electrical connectors 2 have a metal core 21, which electrically connects the electrodes 11 of two adjacent solar cells 1 through a bonding material 22.

[0033] The bonding material 22 can be a bonding material included with the electrical connector 2, or it can be a bonding material separately provided independent of the electrical connector 2. For example, the bonding material 22 can be a separately provided solder paste, tin alloy material, etc. No specific limitation is made. For example, in Figure 1, the bonding material 22 can be a bonding material included with the electrical connector 2. The bonding material 22 can also be a combination of a bonding material included with the electrical connector 2 and a separately provided solder paste or other bonding material.

[0034] It should be noted that the main component of the bonding material is tin. On the one hand, tin has a low melting point, resulting in low energy consumption in the interconnection process and a simple connection process. On the other hand, tin has good fluidity in the molten state, making it easy to form a good coating or coverage with the metal cores of common electrical connectors, such as copper cores.

[0035] A first alloy layer 31 is formed between the bonding material 22 and the metal core 21. This first alloy layer 31 can be an intermetallic compound (IMC), serving as the 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 solar cells using this electrical connector 2 mainly involves surface wetting, interatomic diffusion, dissolution, and metallurgical bonding. This is a very complex chemical reaction, and the formation of a good IMC is a key indicator of the connection quality. Referring to Figure 6, the electrical connector 2 specifically connects the positive electrode of one solar cell to the negative electrode of another adjacent solar cell to achieve interconnection.

[0036] It should be noted that the first alloy layer and the second alloy layer described below can be two substances that have formed relatively stable chemical bonds, so as to exist as an electromechanical connector to conduct and transmit current.

[0037] This application addresses the connection reliability issue of photovoltaic modules from four main perspectives. The first perspective focuses on improving the characteristics of the first alloy layer to enhance and ensure the connection reliability of the photovoltaic module. The second perspective focuses on improving the second alloy layer 32 formed between the electrode 11 and the bonding material 22 to improve the connection reliability of the photovoltaic module. The third perspective focuses on improving the characteristics of a connection point between the electrical connector 2 and the electrode 11 to improve the connection reliability of the photovoltaic module. The fourth perspective focuses on controlling the morphological characteristics of the electrical connector 2 and the electrode 11 to improve the connection reliability of the photovoltaic module. Through research at these four perspectives, this application significantly improves the connection reliability of photovoltaic modules, reduces the risk of electrical connectors detaching from the cells during the long service life of the photovoltaic module, and improves the quality and reliability of the photovoltaic module. It should be understood that any one of the above four improvements can achieve the improvement in the connection reliability between the electrical connector and the cell; multiple improvements can also be combined to achieve better results. The improvements to the photovoltaic module at each of the four perspectives will be described below, starting from the first perspective.

[0038] The main content of the first layer will now be described in detail. Figures 2 and 3 are partial SEM (Scanning Electron Microscope) images of the first cross-section of the photovoltaic module. The first cross-section is a section of the photovoltaic module perpendicular to the length extension direction of the metal core 21. In Figure 1, the direction perpendicular to the paper is the length extension direction of the metal core 21. In the first cross-section, the first alloy layer 31 covers more than 80% of the outline of the metal core 21. That is to say, in the first cross-section, the first alloy layer 31 covers most of the outline of the metal core 21, and the first alloy layer formed between the bonding material 22 and the metal core 21 provides relatively complete coverage of the metal core 21. On the one hand, a greater degree of coverage of the metal core can ensure a higher reliability of the connection between the metal core 21 and the bonding material 22, reducing the risk of the metal core coming off the bonding material due to tension or other reasons. On the other hand, it ensures that most of the surface of the metal core is covered by the first alloy layer and remains in a non-exposed state. This reduces the risk of the metal core being corroded or oxidized by moisture during the long-term service of the photovoltaic module, thus ensuring the stability of the metal core's conductivity and physicochemical properties. Therefore, when the first alloy layer covers a large portion of the metal core, i.e., more than 80%, the photovoltaic module exhibits better electrical connection reliability, conductivity, and structural stability.

[0039] 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 core 21.

[0040] In some embodiments, in the first cross-section, the first alloy layer 31 covers more than 90% of the outline of the metal core 21. This mainly means that the first alloy layer 31 covers more of the outline of the metal core 21, and the first alloy layer forms a more complete coverage of the metal core 21 between the bonding material 22 and the metal core 21. 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.

[0041] 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 outline of the metal core 21.

[0042] In some embodiments, in the first cross-section, the first alloy layer 31 includes an inner contour close to the metal core 21 and an outer contour away from the metal core 21, wherein the ratio of the length of the outer contour to the circumference of the contour line of the metal core 21 is (0.8 to 5):1. In this case, it can be ensured that both the inner and outer contours of the first alloy layer cover the metal core, meaning that the first alloy layer covering the metal core has sufficient thickness to achieve a good fixing and covering effect.

[0043] The perimeter of the outer contour of the first alloy layer 31 refers to the total length of the outer contour lines of the first alloy layer 31. For example, if the outer contour of the first alloy layer 31 is arc-shaped or circular, then the length of the outer contour is the perimeter 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, then the length of the outer contour is 2πr. The perimeter of the contour lines of the metal core 21 refers to the total length of the contour lines of the metal core 21 within the first cross-section. For example, if the metal core 21 is a circular metal core with a radius of x, then the perimeter of its contour lines is 2πx. For example, if the metal core 21 is a flat metal core, its outline in the first cross-section is a rectangle. The lengths of the two perpendicular sides of the rectangle are a and b, where a can be the width of the flat metal core and b can be the thickness of the flat metal core. The directions of the length, width, and thickness of the flat metal core are perpendicular to each other, so the perimeter of its outline is 2a + 2b. When the outer outline of the first alloy layer is irregular, its perimeter is the length of the irregular outer outline.

[0044] For example, in the first cross-section, the ratio of the length of the outer contour of the first alloy layer 31 to the perimeter 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.

[0045] In some embodiments, the thickness of the first alloy layer 31 is between 0.5 μm and 4 μm, and the direction of the thickness of the first alloy layer 31 points from its outer contour to its inner contour. When the thickness of the first alloy layer 31 is within this range, the thickness of the first alloy layer covering the metal core is suitable, and the mechanical connection strength of the first alloy layer is good and its physicochemical properties are relatively stable. More specifically, if the thickness of the first alloy layer 31 is less than 0.5 μm, a strong and reliable mechanical connection is not formed between the metal 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 degree of brittleness and is prone to breakage. It should be noted that for a single metal core 21, the thickness of the first alloy layer 31 at different locations may not be exactly the same; the thickness of the first alloy layer here may refer to the maximum thickness within a certain region of the first alloy layer 31.

[0046] For example, the thickness of the first alloy layer 31 can be 0.5μm, 0.55μm, 0.9μm, 1μm, 1.05μm, 1.5μm, 2μm, 2.5μm, 2.9μm, 3μm, 3.5μm, 3.9μm, or 4μm.

[0047] In some embodiments, referring to FIG3, the first alloy layer 31 surrounds the metal core 21 in a wave-like pattern. The main component of the first alloy layer includes a tin-copper intermetallic compound. Specifically, the main component of the bonding material is a metal such as tin. The uneven distribution of the main metal components in the bonding material makes it easier to form a continuous IMC in a wave-like pattern, further ensuring maximum coverage of the metal core 21 and further improving the connection reliability of the metal core. The main component of the first alloy layer is determined by the bonding material and the metal core. Different bonding materials combined with different metal cores can form first alloy layers of different materials. When the main component of the first alloy layer includes a tin-copper intermetallic compound (such as Cu6Sn5), its material properties are relatively stable, and the materials are easy to bond together, thereby enabling the manufactured photovoltaic module to have good electrical connection performance.

[0048] In some embodiments, referring to FIG3, in the first cross-section, the first alloy layer 31 includes an inner contour and an outer contour, the inner contour and the outer contour being as described above. The metal core 21 is a circular metal core, and the ratio of the circumference of the outline of the metal core to the length of the outer contour of the first alloy layer is from 2πx:2π(x+0.5) to 2πx:2π(x+4); where x is the radius of the metal core in mm. In actual production, the formation of the first alloy layer, that is, the length of the outer contour of the first alloy layer, can be appropriately controlled according to the size of the circular metal core, thereby achieving a better connection, fixation, and covering effect.

[0049] For example, the metal core 21 is a circular metal core. When the radius x of the metal core is 1 mm, the ratio of the perimeter of the outline of the metal core 21 to the length of the outer outline of the first alloy layer 31 can be from 4π:6π to 4π:10π.

[0050] The metal core 21 is a flat metal core. The ratio of the perimeter of the metal core's outline 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 core and 'b' is the thickness of the metal core, both in mm. In actual production, the formation of the first alloy layer, such as its thickness and coverage, can be controlled based on the width and thickness of the flat metal core, thus achieving better connection, fixation, and coverage. For example, the cross-sectional shape of the flat metal core can be rectangular, square, elliptical, thick in the middle and thin on both sides, spindle-shaped, etc.

[0051] For example, if the metal core 21 is a flat metal core with a width a of 2 mm and a thickness of 4 mm, the ratio of the perimeter of the outline of the metal core 21 to the length of the outer outline of the first alloy layer 31 can be from 12:22.5 to 12:96.

[0052] In some embodiments, the metal core 21 can be a triangular metal core, and the ratio of the perimeter of the outline of the metal 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); where m, n, and p are the side lengths of the cross-section of the metal core, all in mm. The triangular metal core refers to a metal core with a triangular cross-sectional shape, such as an isosceles triangle or a non-isosceles triangle. For example, when the side m of the triangular metal core is 2 mm, n is 1.5 mm, and p is 1.5 mm, the ratio of the perimeter of the outline of the metal core 21 to the length of the outer contour of the first alloy layer 31 can be 5:6.5 to 5:17. In this case, the coverage degree and thickness of the important connecting layer, the first alloy layer, can be adjusted by adjusting the interconnection process according to the size of the metal core.

[0053] In some embodiments, in the first cross-section, the cross-sectional area of ​​the metal core 21 is greater than or equal to 0.00785 mm². 2 The metal core 21 has a large cross-sectional area and low resistivity, resulting in better current transmission.

[0054] For example, in the first cross-section, the cross-sectional area of ​​the metal core 21 can be 0.00785 mm². 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 .

[0055] In some embodiments, the metal core 21 includes a copper core. The metal core is not only low-cost but also has good electrical conductivity. For example, the metal core 21 is a circular copper core with a diameter of 0.1 mm to 0.5 mm.

[0056] In some embodiments, in the first cross-section, the bonding material 22 covers more than 80% of the outline of the metal core 21. In this first cross-section, the bonding material 22 covers a larger portion of the metal core 21. This results in a larger contact area between the bonding material and the metal core, facilitating the formation of a reliable first alloy layer. Furthermore, in the first cross-section, when the metal core has a circular cross-section, the bonding material covers the circular metal core beyond its center, effectively encasing and clamping the circular metal core. When the metal core has a flat cross-section, the bonding material covers most of both sides of the flat metal core, even covering its top, making it difficult for the flat metal core to detach from the bonding material, thus achieving a better connection effect. Even if the first alloy layer fails, the metal core can still be fixed by the bonding material.

[0057] 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 outline of the metal core 21.

[0058] In some embodiments, as shown in FIG2, in the first cross-section, the width of the bonding material 22 in contact with the electrode 11 and the solar cell is greater than the width of the metal core 21. This 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 of the bonding material is wider, the bonding material with the metal core fixed has a larger contact area on the solar cell, which is beneficial for forming a high-quality alloy layer with a large area between the electrode and the bonding material. Moreover, the structure with a larger lower end and a smaller upper end is beneficial for fixing the bonding material and the metal core on the surface of the solar cell, which can improve the connection reliability of the photovoltaic module.

[0059] In some embodiments, the bonding material is a single bonding material, that is, the source of the bonding material is singular. It can be a bonding material wrapped around the metal core of the electrical connector 2, or the bonding material can be a bonding material separately disposed between the metal core and the electrode.

[0060] 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 sides of the first bonding material, as shown in Figure 4. The second bonding material is manufactured independently of the first bonding material, for example, using solder paste. The source of this bonding material is flexible and diverse, suitable for various scenarios. The second bonding material can supplement the first bonding material, enhancing the bonding strength between the electrode and the metal core, and can also increase the contact area between the first bonding material and the battery cell, thereby increasing the area of ​​the second alloy layer. As can be seen from Figure 4, due to the addition of the second bonding material, the volume of the bonding material increases, and its covering and fixing effect on the sides of the metal core is significantly enhanced.

[0061] The main contents of the second layer are described in detail below. Referring to Figure 1, a second alloy layer 32 is formed between the electrode 11 and the bonding material 22. This second alloy layer 32 acts 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 realizing reliable and effective current collection.

[0062] As mentioned above, the main component of the bonding material 21 is tin, and the material of the electrode 11 is typically silver, copper, nickel, etc. Therefore, the second alloy layer 32 includes: a silver-tin intermetallic compound (such as Ag3Sn), a copper-tin intermetallic compound, or a tin-nickel intermetallic compound. The aforementioned electrode exhibits good conductivity, and the aforementioned second alloy layer 32 has low resistivity and good conductivity. No specific limitation is made on the mass ratio of tin to silver in the silver-tin intermetallic compound. No specific limitation is made on the mass ratio of copper to tin in the copper-tin intermetallic compound. No specific limitation is made on the mass ratio of nickel to tin in the tin-nickel intermetallic compound.

[0063] In some embodiments, referring to FIG1, on one surface of a battery cell 1, the total length of the second alloy layer at the location of an electrical connector 2 is L1. Here, "surface" refers to the surface on which the electrodes 11 are disposed in the battery cell; it can refer only to the backlight surface, or it can be both the light-facing and backlight-facing surfaces. During normal operation of the battery cell, the primary absorption surface is its light-facing surface, with the backlight surface and light-facing surface opposite each other. The electrical connector can be a solder strip, or a conductive layer on a conductive backplate connecting adjacent battery cells, etc. The length of the portion of an electrical connector 2 located on this surface of the battery cell is L2, and the direction of this length is parallel to the extension direction of the electrical connector 2. Typically, an electrical connector 2 needs to extend approximately from near the head of one battery cell, across the gap between two battery cells, to near the tail of its adjacent battery cell. Here, the ratio of L1 to L2 is greater than or equal to 2.1%, meaning that the total length L1 of the second alloy layer at the location 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 this surface. When the total length L1 of the second alloy layer on one surface of a solar cell 1—that is, the portion where the electrodes and electrical connectors are alloyed—accounts for more than 2.1% of the length of the electrical connectors, it ensures sufficient current collection and transmission channels, resulting in good current collection performance. Furthermore, it provides adequate alloy bonding between the electrodes and electrical connectors, ensuring the reliability of the connector connection. When the ratio of L1 to L2 is less than 2.1%, the current collection and transmission channels are insufficient, leading to some current loss and reducing the performance of the photovoltaic module. It should be noted that this applies to both solar cells with and without busbars; the ratio of L1 to L2 must be greater than or equal to 2.1%. 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%.

[0064] Optionally, on one surface of a solar cell 1, the second alloy layer at the location of an electrical connector 2 can be divided into multiple sections, specifically five or more connection points. For example, six, seven, eight, ten, or even twenty connection points. The spacing between each connection point should be less than 5mm. For example, the spacing differences between connection points could be 5mm, 4mm, 3mm, 2mm, 1mm, or 0.5mm. In this case, the second alloy layer of the electrical connector on the solar cell is not centrally designed, but rather distributed at multiple points in a relatively uniform manner. This design makes the points where current converges on the electrical connector more dispersed and uniform, which is beneficial for rapid current collection and reduces current loss. Furthermore, compared to connecting and fixing at a single point, this multi-point, more uniform fixing provides better fixation and reduces the likelihood of problems such as partial detachment or warping of the electrical connection wires.

[0065] It should be noted that when multiple electrical connectors are present on one surface of a solar cell, one electrical connector conforming to the above design is sufficient to achieve a certain effect. L1 and L2 represent the total length of one electrical connector and the second alloy layer beneath it on one surface of the solar cell. This second alloy layer is approximately arrayed on one surface of the solar cell.

[0066] In some embodiments, the solar cell includes a first surface and a second surface, one of which is a light-facing surface and the other a back-facing surface. Electrodes are disposed on both the first and second surfaces, meaning the solar cell is a double-sided electrode solar cell. For both 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 still refers to the total length of the second alloy layer at an electrical connection location on one surface of the solar cell. For the first surface, the ratio of L1 to L2 is greater than or equal to 2.85%. The second surface is similarly configured. For the light-facing and back-facing surfaces of the double-sided solar cell, the proportion of the total length of the second alloy layer on both surfaces is greater than 2.85%, which can make the current collection on the two surfaces more balanced, reducing current loss caused by current mismatch. It can also improve the stability and balance of the connection force of the electrical connectors on the two surfaces, reducing problems such as microcracks and fragmentation caused by uneven tension on the two opposing surfaces of the solar cell. It should be noted that, regardless of whether the solar cell has a busbar or not, the ratio of L1 to L2 is greater than or equal to 2.85%.

[0067] For example, the solar cell includes opposing first and second surfaces, each with electrodes. The ratio of L1 to L2 for the first and second surfaces can be 2.85%, 2.9%, 2.91%, 2.92%, 2.98%, 3%, 3.1%, 3.4%, 3.2%, or 3.5%. As another example, the solar cell includes opposing first and second surfaces, each with electrodes. For a solar cell with busbars, L1 can be approximately 7.12 mm; for a solar cell without busbars, L1 can be approximately 2.997 mm, and L2 is approximately 80 mm to 105 mm.

[0068] The bifacial solar cells here can be TOPCon (passivated contact) solar cells, heterojunction solar cells, etc., and there is no limitation on the specific type of solar cell.

[0069] In some embodiments, the solar cell includes a first surface and a second surface, one of which is a light-facing surface and the other a back-facing surface. Electrodes are disposed only on the first surface, which can refer to the back-facing surface, meaning the solar cell is a back-contact or single-sided solar cell. For the first surface, the ratio of L1 to L2 is greater than or equal to 4.2%. For a solar cell with electrodes on one side or a back-contact solar cell with electrodes on the back-facing surface, both the electrodes and the electrical connectors connecting the electrodes are located on one side of the solar cell. In this case, by appropriately increasing the area of ​​the second alloy layer corresponding to one electrical connector, that is, appropriately increasing the alloy connection area between the electrode and the electrical connector, the stress and current convergence points can be dispersed. This improves the current collection and transmission effect, enhances connection stability, and makes the force between the electrical connector and the solar cell more uniform and dispersed, reducing the risk of microcracks and fragmentation of the solar cell. Simultaneously, the convergence of current at multiple points over a larger area can improve current collection efficiency and reduce losses.

[0070] It should be noted that, regardless of whether the solar cell has busbars or not, the ratio of L1 to L2 is greater than or equal to 4.2%. For example, if the solar cell includes opposing first and second surfaces, with electrodes only on the first surface, the ratio of L1 to L2 for the first surface 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%. As another example, if the solar cell includes opposing first and second surfaces, with electrodes only on the first surface, for a solar cell with busbars, L1 can be approximately 11 mm; for a solar cell without busbars, L1 can be approximately 2.16 mm to 5.4 mm or approximately 10.48 mm, and L2 is approximately 80 mm to 105 mm.

[0071] The single-sided or back-contact solar cell here can be a back-contact heterojunction solar cell, an interdigitated back-contact solar cell, a back-contact solar cell with a tunneling passivation layer, etc., and there is no limitation on the specific type of solar cell.

[0072] In some embodiments, the electrode 11 includes a current collector electrode, the extension direction of which is parallel to the extension direction of the electrical connector. The current collector electrode is disposed corresponding to the N-type doped layer and the P-type doped layer. Typically, there are no busbars in this solar cell; the electrical connector is directly disposed on the current collector electrode, therefore the ratio of L1 to L2 is greater than or equal to 60%. That is, on one surface of the solar cell, the total length of the second alloy layer at the location of an electrical connector is L1, and the length of the portion of an electrical connector located on one surface of the solar cell is L2, with the ratio of L1 to L2 being greater than or equal to 60%. For this photovoltaic module, the length of the second alloy layer is significantly increased, meaning the length of an electrical connector used for current focusing and fixed connection is significantly increased, resulting in better current focusing effect and electrical connection reliability.

[0073] Furthermore, the electrode 11 includes a current collector electrode, the extension direction of which 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 current collector electrode, the extension direction of which 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%, or 90%. In this case, the current gathering and electrical connection effect of the electrical connector can be further improved.

[0074] In some embodiments, on one surface of a solar cell 1, the total length of the second alloy layer 32 at the location of an electrical connector 2 is L1. On another surface of a solar cell 1, the total length of the first alloy layer at the location of an electrical connector 2 is L3, and the direction of the length is parallel to the extension direction of the electrical connector 2. This surface is also the light-facing or backlight-facing surface of the solar cell. The ratio of L1 to L3 is greater than or equal to 2%. 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 reliably fix the metal core, but also the bonding material can reliably connect to the electrode. More specifically, when the ratio of L1 to L3 is less than 2%, the current collection and transmission channels are insufficient, resulting in a certain loss in current collection and reducing the performance of the photovoltaic module.

[0075] It should be noted that, regardless of whether the solar cell has busbars or not, the ratio of L1 to L3 must be 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 also be noted that when a solar cell has multiple electrical connectors on one surface, at least one connector's alloy layer design must conform to the above design. Of course, if more or all electrical connectors have alloy layer designs conforming to the above design, the photovoltaic module will have better electrical connection reliability and current transmission performance.

[0076] In some embodiments, an electrical connector 2 connects two adjacent battery cells 1. Multiple second alloy layers 32 are present between the electrical connector and the two battery cells 1. Along the length of the electrical connector 2, the length of the second alloy layers located at the head and / or tail is greater than the length of the second alloy layers located in the middle. Along the length of the electrical connector 2, the second alloy layers located at the head and / or tail are mainly the second alloy layers at the ends of the electrical connector. Compared to the second alloy layers located in the middle, the ends are more prone to bending, warping, etc. Therefore, the connection quality of the second alloy layers at the ends has a greater impact on the electrical connector and the two battery cells 1. In this application, the length of the second alloy layers at the ends is longer, allowing them to accommodate possible bending, warping, etc., and maintaining good conductivity even under the aforementioned potential adverse effects. The number of second alloy layers included in a single electrical connector is not limited.

[0077] Optionally, the end of the electrical connector on the solar cell is provided with a connecting portion, and the width of the connecting portion is greater than the width of the current 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 larger, making it easier to achieve a reliable electrical connection and preventing the end of the electrical connector from lifting or detaching.

[0078] The main content of the third layer will now be described in detail. 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 this width is perpendicular to the extension direction of the electrical connector 2 and perpendicular to the thickness direction Q of the solar cell. The larger width of the second alloy layer 32 at a single connection point allows for a larger electrical connection amplitude between the connection point and the electrical connector 2, resulting in a more robust and reliable connection. Specifically, the electrode 1 can have multiple connection points, for example, 7 to 20 connection points on one electrode 1. Each of these connection points forms a second alloy layer with 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 area of ​​the second alloy layer is relatively small, and the second alloy layer at the connection point is prone to separation in cases such as bending of the photovoltaic module.

[0079] 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 time, 1.5 times, 2 times, 3 times, etc., the width of the metal core 21.

[0080] In some embodiments, referring to FIG1, the electrical connector 2 is a flat electrical connector. In the aforementioned first cross-section, the shape of the electrical connector 2 is approximately rectangular, square, or a rectangle with chamfers. Compared to a circular electrical connector, the contact between the flat electrical connector and the electrode is primarily surface-to-surface contact, resulting in a larger contact area, more stable interconnection, and higher interconnection reliability compared to the surface-to-line contact between the electrode and a circular electrical connector. Furthermore, without reducing the cross-sectional area (and without increasing resistivity), a flat electrical connector can be achieved by increasing its width and reducing its thickness. A thinner flat electrical connector can significantly reduce the risk of microcracks and cell cracking in the solar cell.

[0081] 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. This allows the lower side of the second alloy layer to be wider than the upper side of the metal core, enabling the second alloy layer to effectively fix the metal core. Furthermore, the contact point between the bonding material and the electrode is usually relatively weak and prone to cracking. When the width of the second alloy layer is greater than that of the metal core, the connection width is larger, resulting in greater connection strength. From the metal core to the bonding material and the electrode, the second alloy layer, as the connection base, is more stable. In addition, if the width of the second alloy layer is less than four times the width of the metal core, the amount of bonding material used and its coverage area can be appropriately reduced, avoiding excessive material costs and 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, thereby determining whether the process meets the standards and whether the electrical connection of the connection point meets the standards.

[0082] 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.

[0083] In some embodiments, referring to FIG5, 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 solar cell 1. At this single connection point, since the metal core 21 is circular, the bonding material can effectively enclose and fix the metal core in a shell shape. Therefore, a reliable connection can be achieved when the width of the second alloy layer is more than 0.3 times the width of the metal core, meeting the reliability requirements during the service life of the photovoltaic module. Furthermore, the width ratio of the second alloy layer 32 is suitable at this time, achieving a good balance between cost and conductivity.

[0084] 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 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, etc.

[0085] 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 relatively large length of the second alloy layer results in a more robust and reliable connection between the connection point and the electrical connector, leading to excellent connection performance of the photovoltaic module.

[0086] 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.

[0087] The second alloy layer 32 is laid flat on the solar cell 1, and the second alloy layer 32 is continuously wavy. The second alloy layer 32 is mainly an alloy formed by bonding materials and electrodes. The main component of the bonding material is tin, which is unevenly distributed. The wavy shape makes it easier to form a continuous IMC (Integrated Molding Complex), further ensuring complete coverage of the metal core and electrodes and improving the reliability of the electrical connection. Moreover, the wavy shape can also disperse stress and avoid stress concentration. The state of the second alloy layer 32 is usually not to wrap around or surround the electrodes. In this way, regardless of the shape of the metal core or electrical connector, it forms a surface-to-surface contact with the electrodes, with a larger contact area, stronger bonding force, and better connection reliability. In the wavy second alloy layer 32, the distance between the troughs and peaks can be 0.5μm to 2μm. The thickness of the second alloy layer 32 is appropriate, with good conductivity, and the second alloy layer is not too thick, because an excessively thick second alloy layer is prone to brittle fracture.

[0088] 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 appropriate, which can not only ensure the connection quality and avoid the electrical connection being substandard due to insufficient IMC, but also prevent the IMC from being too thick, because an excessively thick IMC is too brittle and prone to breakage, thereby improving the reliability of the electrical connection and the connection of the battery cell.

[0089] For example, the thickness of the second alloy layer 32 can be 1μm, 1.2μm, 1.5μm, 1.7μm, 2μm, 2.1μm, 2.5μm, 2.8μm, 3μm, 3.1μm, 3.5μm, 4μm, 4.5μm, or 5μm.

[0090] In some embodiments, the second alloy layer includes 32: a silver-tin intermetallic compound, 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; different choices of the bonding material and electrode material can result in alloy layers of different materials. When the second alloy layer includes a silver-tin intermetallic compound, a copper-tin intermetallic compound, or a nickel-tin intermetallic compound, the second alloy layer of this material has relatively stable properties, good conductivity, strong connection reliability, and is easy to process. There is no specific limitation on the mass ratio of tin to silver in the silver-tin intermetallic compound. There is no specific limitation on the mass ratio of copper to tin in the copper-tin intermetallic compound. There is no specific limitation on the mass ratio of nickel to tin in the nickel-tin intermetallic compound.

[0091] In some embodiments, a plane perpendicular to the thickness direction Q of the battery cell 1 is a first plane, which 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 area of ​​the intersection is greater than or equal to 50% and less than or equal to 100% of the area of ​​the second projection. In this case, the area of ​​the intersection is a large proportion of the area of ​​the second projection of the metal core 21, which can prevent the electrical connector from being set too off-center and reduce the risk of pull-out. More specifically, during the formation of the electrical connection, the electrical connector may be slightly offset and may not be located exactly in the center of the electrode connection point. Due to the leveling of the bonding material, the second alloy layer is usually located at the exact center of the electrode connection point. The metal core of the electrical connector may be misaligned. From a top view, the metal core and the second alloy layer may not overlap 100%, with the overlapping area accounting for 50% to 100% of the projected area of ​​the metal core. Circular electrical connectors may roll, and flat electrical connectors may have alignment accuracy errors. However, the electrode connection point is usually fixed, so the position of the second alloy layer is roughly fixed or definite. The position of the electrical connector may be offset. This application limits the offset of the electrical connector to a small size, further improving the connection effect and reducing the risk of pull-out.

[0092] For example, a plane perpendicular to the thickness direction Q of the battery cell 1 is a first plane. This 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 intersecting area to the area of ​​the second projection can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%.

[0093] In some embodiments, the solar cell 1 is provided with a connecting portion, which may be a solder pad or a thickened section on the current collector electrode, etc. The bonding material 21 is fixed and electrically connected to the electrode 1 through the connecting portion. On the solar cell 1, the width of the connecting portion is greater than or equal to the width of the electrode. The larger width of the connecting portion results in a larger connection area between the connecting portion and the bonding material, allowing the bonding material to have a larger adhesion area on the solar cell. This improves the connection reliability of the bonding material and electrical connectors, and also enhances the current gathering and transmission effect. In addition, it can prevent the bonding material from overflowing from the connecting portion.

[0094] In some embodiments, the surface of the connection portion near the electrical connector 2 is a third surface, which is the surface of the connection portion facing away from the battery cell. The second alloy layer 32 covers at least 20% of the third surface, and at most exceeds 20% of the third surface. On the one hand, the second alloy layer covers a relatively large portion of the third surface, ensuring the reliability of the electrical connection; on the other hand, the portion of the second alloy layer exceeding the connection portion is small, reducing the risk of short circuits. Specifically, when the main component of the bonding material includes tin, the connection portion has a certain adhesion effect on the tin in the bonding material, further preventing the bonding material from overflowing from the connection portion.

[0095] In some embodiments, referring to Figure 6, an electrical connector 2 connects two adjacent battery cells 1. In Figure 6, the black dots 111 represent the connection portions. The battery cell 1 on the left can be the preceding battery cell, and the battery cell 1 on the right can be the following battery cell. The length between the first position of the connection portion at the tail of the preceding battery cell and the second position of the connection portion at the head of the adjacent following battery cell 1 is L4. The distance between adjacent connection portions 111 on a battery cell 1 is L5, and the ratio of L5 to L4 is 1:(0.8-1.5). The positions on an electrical connector that connect to each connection portion 111 are the force application points, resulting in a relatively uniform distribution of force application points on the electrical connector. This means that the shear force on each IMC is basically uniform, ensuring the reliability of the IMC and preventing failure. It should be noted that the total number of connection portions on a battery cell 1 is not specifically limited.

[0096] For example, an electrical connector 2 connects two adjacent battery cells 1. The length between the first position of the connection at the tail end of the preceding battery cell and the second position of the connection at the head end of the adjacent following battery cell on the electrical connector 2 is L4. The distance between adjacent connection parts 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.

[0097] In some embodiments, in a direction perpendicular to both the extension direction of the electrical connector 2 and the thickness direction Q of the battery cell, the distance between the centers of adjacent connecting portions on the same side of the battery cell 1 is less than or equal to 2 mm. This means that in a direction perpendicular to both the length direction and the Q direction of the electrical connector, the centers of adjacent connecting portions are as collinear as possible. Consequently, the force acting on the electrical connector is more uniform throughout the entire electrical connector, resulting in a more reliable connection. Furthermore, 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 connecting portions is smaller. This means the entire electrical connector does not require significant twisting to accommodate the alignment error between the connecting portions; that is, the degree of twisting of the entire electrical connector is smaller, resulting in less shear force introduced into the electrical connector. Consequently, the shear force acting on the entire electrical connector is smaller, leading to a more reliable connection.

[0098] For example, in a direction perpendicular to both the extension direction of the electrical connector 2 and the thickness direction Q of the battery cell, the distance between the centers of adjacent connectors 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.

[0099] In some embodiments, the same solar cell 1 includes at least two sizes of connection portions, meaning that the same solar cell has both large and small connection portions. The large connection portion can improve current carrying capacity, enhance mechanical connection strength, and improve connection reliability, while the small connection portion can reduce shading and save space. Therefore, the photovoltaic module of this application not only ensures contact area and IMC area, but also has good connection reliability, low resistance, and less shading. It should be noted that the large connection portion can be located at the edge of the solar cell, and the small connection portion can be located inside the large connection portion. The large connection portion being located at the edge of the solar cell can improve the current collection effect at the edge of the solar cell.

[0100] The following details the main content of the fourth layer. In the photovoltaic module, the second cross-section is parallel to and perpendicular to the extension direction of the electrical connector 2, and perpendicular to the first cross-section. In either the first or second cross-section, referring to Figure 7, the second alloy layer 32 includes discrete second alloy points 321. These discrete points 321 can uniformly bear the connection force, improving the reliability and stability of the connection. The electrode here can be a low-temperature electrode, with a sintering temperature lower than that of a high-temperature electrode. The main materials for the low-temperature electrode can be selected from: micro / nano silver materials, micro / nano silver-coated copper materials, nano silver materials, micron-sized copper materials, nano copper materials, etc. These materials have good conductivity and good adhesion. More specifically, since the low-temperature electrode paste is mainly composed of micron-sized spherical metal particles and microparticle-shaped sheet metal bonded together with organic matter, the surface of the solidified low-temperature silver paste is uneven, forming a bumpy surface. Furthermore, after the electrode is formed, the metal clusters within the electrode are relatively dispersed. In this configuration, discrete second alloy points facilitate the formation of sufficient bonding alloy between the electrode and the bonding material. These discrete points enable multi-point contact between the electrode and the bonding material, achieving not only stress dispersion but also reliable electrical connection between them. It should be noted that a continuous second alloy layer still exists within the second alloy layer.

[0101] 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 or second cross section. That is to say, 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 uniformly distributed, which can further uniformly bear the connection force and improve the reliability and stability of the connection.

[0102] For example, the length of the second alloy point 321 can be 2μm, 1.9μm, 1.8μm, 1.5μm, 1.3μm, 1μm, 0.9μm, 0.8μm, 0.5μm, 0.2μm, 0.1μm, 0.05μm, 0.01μm, 0.03μm, or 0.005μm.

[0103] In some embodiments, for a single battery cell 1, the spacing between adjacent discrete second alloy points 321 is less than or equal to 1 μm. The smaller spacing between adjacent discrete second alloy points 321 results in better electrical conductivity.

[0104] For example, for a single battery cell 1, the spacing 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, or 0.005 μm.

[0105] In some embodiments, adjacent discrete second alloy points 321 are filled with a bonding material and / or an electrode material. Both the bonding material and the electrode material have good electrical conductivity, which can improve the current transmission effect, and the aforementioned materials have a certain degree of viscosity, which can also improve the bonding force.

[0106] In some embodiments, the electrodes described above are printed on the surface of a solar cell, the surface of which has a textured surface. That is, electrodes with discrete second alloy points can be applied to surfaces with a textured surface, and these discrete second alloy points provide good adhesion and pull-out force between the electrode and the textured surface, resulting in better electrical connection reliability. It should be noted that the electrodes can also be applied to polished surfaces, but the connection force between the electrode and the textured surface is even greater.

[0107] In Figure 1, the direction perpendicular to the paper is the length extension direction of the metal 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. This first cross-section is a cross-section in the photovoltaic module perpendicular to the length extension direction of the metal core 21. The electrode slurry typically contains metal particles and organic matter. During the drying and curing process, the metal particles agglomerate. The agglomerated metal particles may be separated by the aforementioned organic matter. The agglomerated metal particles are the metal clusters here. The distance between the metal clusters is small, the metal density is high, the electrode has good conductivity, and the current collection effect is good.

[0108] For example, in the first cross-section, the distance between 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. This distance refers to the minimum distance between two metal clusters.

[0109] In some embodiments, in the photovoltaic module of this application, the connection tension between the high-temperature electrode and the electrical connector can be greater than or equal to 1.5 N / mm. 2 The tensile force connecting the low-temperature electrode and the electrical connector can be greater than or equal to 1.2 N / mm. 2 The main differences between high-temperature and low-temperature electrodes lie in their material composition and sintering temperature. High-temperature electrodes typically have a higher sintering temperature than low-temperature electrodes, and they often contain glass powder. For both high-temperature and low-temperature electrodes, the lower limit of the connection tensile force is appropriately set to ensure connection quality and avoid the problem of excessive brittleness and breakage caused by over-connection.

[0110] 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. 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, the shear force introduced into the electrical connector is small, and thus the shear force acting on the electrical connector is small, making the connection more reliable.

[0111] 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.

[0112] In some embodiments, referring to FIG6, 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 electrical connector 2 to the length of the battery cell is appropriate, which can ensure sufficient electrical connection area and reliable current transmission. This not only reduces current transmission loss, but also minimizes the heat impact on the battery cell during the electrical connection process.

[0113] For example, an electrical connector 2 connects two adjacent battery cells 1. Along the extending 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%.

[0114] In some embodiments, the electrical connector mentioned throughout this document can be a solder strip, and the main material of the bonding material includes tin, such as solder paste, tin-lead alloy, tin-lead-bismuth alloy, etc. The electrical connector 2 is electrically connected and fixed to the electrode of the solar cell through a welding process and / or a lamination bonding process. The welding process directly welds the electrode of the solar cell and the solder strip together. The lamination bonding process can involve pre-fixing the solder strip and the electrode of the solar cell, and then using 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, adaptable to various scenarios. The welding process here can refer to high-temperature infrared welding or low-temperature infrared welding, etc.

[0115] It should be noted that the aforementioned four levels are detailed descriptions of the photovoltaic module of this application from different perspectives. The relevant parts of the four levels can be referred to each other. In order to avoid repetition, the relevant parts are briefly described.

[0116] This application also provides a photovoltaic system, which includes any of the aforementioned photovoltaic modules arranged in a plurality of arrays. 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 can be installed on the building roof. Other structures of the photovoltaic system are not specifically limited. Compared with photovoltaic modules, the photovoltaic system can further expand the application scenarios of solar cells.

[0117] This photovoltaic system has the same or similar beneficial effects as any of the aforementioned photovoltaic modules, and the relevant parts can be referred to each other. To avoid repetition, they will not be repeated here.

[0118] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0119] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims. All of these forms are within the protection scope of this application.

Claims

1. A photovoltaic module, wherein, include: Battery cells; The battery cell is provided with electrodes; An electrical connector having a metal core; the metal core electrically connects the electrodes of two adjacent battery cells via a bonding material; a first alloy layer is formed between the bonding material and the metal core; a second alloy layer is formed between the electrodes and the bonding material. At one 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 core; The width is perpendicular to the extension direction of the electrical connector and also perpendicular to the thickness direction of the battery cell.

2. The photovoltaic module according to claim 1, wherein, On one surface of the battery cell, at the location of one of the electrical connectors, the total length of the second alloy layer is L1; The length of the 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%.

3. The photovoltaic module according to claim 2, wherein, The battery cell includes: a first surface and a second surface opposite to each other; electrodes are disposed on both the first surface and the second surface. For both the first surface and the second surface, the ratio of L1 to L2 is greater than or equal to 2.85%.

4. The photovoltaic module according to claim 2, wherein, The battery cell includes: a first surface and a second surface opposite to each other; electrodes are disposed only on the first surface. For the first surface, the ratio of L1 to L2 is greater than or equal to 4.2%.

5. The photovoltaic module according to claim 2, wherein, The electrode includes a current collector electrode, the extension direction of which is parallel to the extension direction of the electrical connector; The ratio of L1 to L2 is greater than or equal to 60%.

6. The photovoltaic module according to claim 1, wherein, An electrical connector connects two adjacent battery cells, and the electrical connector and the two battery cells have a plurality of second alloy layers. Along the length direction of the electrical connector, 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.

7. The photovoltaic module according to claim 1, wherein, The electrical connector includes a flat electrical connector.

8. The photovoltaic module according to claim 7, wherein, At one connection point between the electrical connector and the electrode, the ratio of the width of the metal core to the width of the second alloy layer is 1:(1 to 4); The width is perpendicular to the extension direction of the electrical connector and also perpendicular to the thickness direction of the battery cell.

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

10. The photovoltaic module according to claim 1, wherein, At one connection point between the electrical connector and the electrode, the length of the second alloy layer is greater than or equal to 30 μm.

11. The photovoltaic module according to claim 1, wherein, The second alloy layer is laid flat on the battery cell, and the second alloy layer is distributed in a continuous wavy pattern.

12. The photovoltaic module according to claim 1, wherein, The thickness of the second alloy layer is 1 μm to 5 μm; And / or, the second alloy layer comprises: a silver-tin intermetallic compound, a copper-tin intermetallic compound, or a nickel-tin intermetallic compound.

13. The photovoltaic module according to claim 1, wherein, The plane perpendicular to the thickness direction of the battery cell is the 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 area of ​​the intersection is greater than or equal to 50% and less than or equal to 100% of the area of ​​the second projection.

14. The photovoltaic module according to claim 1, wherein, The battery cell is provided with a connecting portion, 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.

15. The photovoltaic module according to claim 14, wherein, The surface of the connecting portion near the electrical connector is a third surface; The second alloy layer covers at least 20% of the third surface, and the second alloy layer extends at most 20% beyond the third surface.

16. The photovoltaic module according to claim 14, wherein, One of the electrical connectors connects two adjacent battery cells; On the aforementioned electrical connector, the length between the first position of the tail connection of the preceding battery cell and the second position of the head connection of the adjacent following battery cell is L4. The distance between adjacent connections on a solar cell is L5; The ratio of L5 to L4 is 1:(0.8-1.5).

17. The photovoltaic module according to claim 14, wherein, 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 connectors on the same side of the battery cell is less than or equal to 2 mm.

18. The photovoltaic module according to claim 14, wherein, The same battery cell contains at least two sizes of connectors.

19. The photovoltaic module according to any one of claims 1 to 18, wherein, A cross section perpendicular to the length extension direction of the metal core is a first cross section, in which the first alloy layer covers more than 80% of the outline of the metal core.

20. The photovoltaic module according to claim 19, wherein, In the first cross-section, the first alloy layer covers more than 90% of the outline of the metal core.

21. The photovoltaic module according to claim 19, wherein, In the first cross-section, the first alloy layer includes an inner contour and an outer contour; the length of the outer contour is in a ratio of (0.8 to 5):1 to the perimeter of the contour line of the metal core.

22. The photovoltaic module according to claim 19, wherein, The thickness of the first alloy layer is 0.5 μm to 4 μm.

23. The photovoltaic module according to claim 19, wherein, The first alloy layer surrounds the metal core in a wave-like pattern; and / or, the main component of the first alloy layer includes a tin-copper intermetallic compound.

24. The photovoltaic module according to claim 19, wherein, In the first cross-section, the first alloy layer includes: an inner contour and an outer contour; The metal core is circular, and the ratio of the perimeter of the metal core's outline to the length of the outer outline of the first alloy layer is between 2πx:2π(x+0.5) and 2πx:2π(x+4); where x is the radius of the metal core in mm; and / or, The metal core is a flat metal core, and the ratio of the perimeter of the outline of the metal core to the length of the outer outline 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 core and 'b' is the thickness of the metal core, both in mm; and / or, The metal core is a triangular metal core, and the ratio of the perimeter of the outline of the metal core to the length of the outer outline of the first alloy layer is (m+n+p):(m+n+p+1.5) to (m+n+p):(m+n+p+12); where m, n, and p are the side lengths of the cross-section of the metal core, and the unit is mm.

25. The photovoltaic module according to claim 19, wherein, In the first cross-section, the cross-sectional area of ​​the metal core is greater than or equal to 0.00785 mm². 2 And / or, the metal core includes: a copper core.

26. The photovoltaic module according to claim 19, wherein, In the first cross-section, the bonding material covers more than 80% of the outline of the metal core; and / or, the width of the bonding material in contact with the electrode is greater than the width of the metal core.

27. The photovoltaic module according to claim 16, wherein, The bonding material is a single bonding material; and / or, The bonding material includes a first bonding material and a second bonding material, wherein the first bonding material covers the outer periphery of the metal core, and the second bonding material covers the bottom and at least part of the sides of the first bonding material.

28. The photovoltaic module according to claim 19, wherein, On one surface of the battery cell: at the location of the electrical connector, the total length of the second alloy layer 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%.

29. The photovoltaic module according to any one of claims 1 to 28, wherein, In either the first or second cross section, the second alloy layer comprises 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.

30. The photovoltaic module according to claim 29, wherein, 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.

31. The photovoltaic module according to claim 29, wherein, The spacing between adjacent discrete second alloy points is less than or equal to 1 μm.

32. The photovoltaic module according to claim 29, wherein, Adjacent discrete second alloy points are filled with a bonding material and / or an electrode material.

33. The photovoltaic module according to claim 29, wherein, 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.

34. The photovoltaic module according to claim 29, wherein, Electrodes are printed on the surface of the battery cell, and the surface of the battery cell has a textured surface.

35. The photovoltaic module according to any one of claims 19 to 26, and 28, wherein, In the first cross section, the distance between the metal clusters in the electrode is less than or equal to 10 μm.

36. The photovoltaic module according to any one of claims 1 to 28, wherein, One of the electrical connectors 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.

37. The photovoltaic module according to any one of claims 1 to 28, wherein, An electrical connector connects two adjacent battery cells, and along the extension direction of the electrical connector, the electrical connector covers 70% to 95% of the length of the battery cell.

38. The photovoltaic module according to any one of claims 1 to 28, wherein, The electrical connector includes a solder strip, the main material of the bonding material includes tin, and the electrical connector is electrically connected and fixed to the electrode by a welding process and / or a lamination process.

39. A photovoltaic system, wherein, include: A photovoltaic module as described in any one of claims 1 to 38; wherein each of the photovoltaic modules is arrayed in a photovoltaic system.

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