Photovoltaic soldering ribbon and photovoltaic module

Abstract

This utility model discloses a photovoltaic ribbon and a photovoltaic module. The photovoltaic ribbon is used in a photovoltaic module, which includes multiple solar cells. The photovoltaic ribbon is configured to connect two adjacent solar cells. The photovoltaic ribbon includes a conductive substrate and a conductive coating. The conductive coating covers the outer periphery of the conductive substrate and is configured to have at least one plane. The at least one plane is configured to connect with the grid lines of the solar cell to conduct current to the conductive substrate. By constructing at least one plane on the surface of the conductive coating of the photovoltaic ribbon, the contact area between the conductive coating of the photovoltaic ribbon and the grid lines on the solar cell to be connected is increased, forming a good ohmic contact and achieving higher photoelectric conversion efficiency.

Description

Technical Field

[0001] This application relates to the field of photovoltaic cell module manufacturing, and more particularly to a photovoltaic welding strip and a photovoltaic module. Background Technology

[0002] In the production process of photovoltaic (PV) modules, the interconnection between solar cells is a crucial step, directly affecting the electrical performance, mechanical stability, encapsulation protection, and photoelectric conversion efficiency of the PV module. Therefore, understanding how to interconnect the individual solar cells is of great significance for improving the electrical performance and reliability of PV modules.

[0003] Currently, adjacent solar cells are mainly connected using photovoltaic ribbons to collect the current converted by the cells. However, in related technologies, the contact area between the photovoltaic ribbons and the grid lines on the solar cells is small, making it difficult to form a good ohmic contact. Utility Model Content

[0004] This utility model discloses a photovoltaic welding strip and a photovoltaic module, which is beneficial to improving the overall power generation efficiency of the photovoltaic module.

[0005] To achieve the above objectives, this utility model discloses a photovoltaic welding ribbon and a photovoltaic module. The photovoltaic welding ribbon is applied to a photovoltaic module, which includes multiple solar cells. The photovoltaic welding ribbon is configured to connect two adjacent solar cells. The photovoltaic welding ribbon includes:

[0006] Conductive substrate;

[0007] A conductive coating is applied to the outer periphery of the conductive substrate. The conductive coating is configured to have at least one plane, which is configured to connect to the grid lines of the solar cell to conduct current to the conductive substrate.

[0008] As an alternative implementation, the conductive coating is configured in a cross-section along its length as at least one of polygon, arc, semicircle, and oval.

[0009] As an alternative implementation, the conductive coating is configured with a trapezoidal cross-section along its length.

[0010] As an optional implementation, the trapezoid includes a top side and a bottom side that are parallel to each other, and two inclined sides connected between the top side and the bottom side, wherein the angle between at least one inclined side and the bottom side is in the range of 45° to 55°.

[0011] The length of the top edge is less than the length of the bottom edge, and the bottom edge is configured to connect to the grid lines of the solar cell.

[0012] As an optional implementation, the conductive coating is made of zinc-aluminum alloy.

[0013] As an alternative implementation, the thickness of the conductive coating is 0.03 mm to 0.08 mm.

[0014] On the other hand, this application also discloses a photovoltaic module, which includes: a plurality of the aforementioned solar cells, and the photovoltaic solder strip. The photovoltaic solder strip is used to electrically connect two adjacent solar cells.

[0015] As an optional implementation, the photovoltaic module further includes an adhesive layer through which the photovoltaic ribbon is bonded to the solar cell.

[0016] As an alternative implementation, the adhesive layer of the photovoltaic module is disposed between the photovoltaic ribbon and the silicon wafer surface of the solar cell.

[0017] As an alternative implementation, there is no welding layer between the photovoltaic module and the solar cell.

[0018] Compared with the prior art, the beneficial effects of this application are:

[0019] This utility model provides a photovoltaic ribbon and a photovoltaic module. The photovoltaic ribbon includes a substrate and a conductive coating, with the conductive coating wrapping around the conductive substrate. The conductive coating is configured with at least one plane for contacting the surface of the solar cell. Therefore, the photovoltaic ribbon and photovoltaic module disclosed in this application, by constructing at least one plane on the surface of the conductive coating of the photovoltaic ribbon, can increase the contact area between the conductive coating of the photovoltaic ribbon and the grid lines on the solar cell, thereby forming a good ohmic contact and facilitating higher photoelectric conversion efficiency. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only 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 This is a schematic diagram of the cross-section of the photovoltaic ribbon disclosed in the embodiments of this application;

[0022] Figure 2 This is a schematic diagram of the structure of photovoltaic ribbon connected to solar cell disclosed in the embodiments of this application;

[0023] Figure 3 yes Figure 2 A magnified view of a section at point A in the middle;

[0024] Figure 4 This is a schematic diagram of the structure of the photovoltaic module disclosed in the embodiments of this application;

[0025] Figure 5 yes Figure 4 A magnified view of a section at point B in the middle;

[0026] Figure 6 This is an exploded view of the overall structure of the photovoltaic module disclosed in the embodiments of this application.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1-Photovoltaic welding ribbon; 11-Conductive substrate; 12-Conductive plating; 121-Flat surface; 122-Top edge; 123-Bottom edge; 124-Beveled edge; 13-Solar cell; 131-Grid line; 2-Photovoltaic module; 21-Adhesive layer; 22-Frame; 23-Glass cover; 24-Encapsulation layer; 25-Backsheet; 26-Gateway box; 27-Busband; 28-Diode. Detailed Implementation

[0029] 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, and 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 this application, the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0031] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0032] Furthermore, the terms "set up," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0033] Furthermore, terms such as "first" are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction) and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0034] Sunlight, in the form of photons, strikes the glass cover of a photovoltaic module, passing through the encapsulation structure to reach the surface of the solar cells. After absorbing the photon energy from the sunlight, a potential difference is created across the two ends of the solar cell. The resulting current is connected to a busbar via photovoltaic ribbons, converging the currents from multiple solar cells and transmitting them to a junction box. The electrical energy processed by the junction box can then be output to external circuits via cables to power loads.

[0035] Therefore, whether the photovoltaic ribbon forms a good ohmic contact with the solar cell during the process of transmitting the current obtained from photoelectric conversion to the outside plays a decisive role in the power generation efficiency of the photovoltaic module.

[0036] Photovoltaic welding ribbons mainly consist of a conductive substrate and a conductive coating. The conductive substrate is usually made of electrolytic copper foil or strip, which has good electrical and thermal conductivity, facilitating current transmission and welding. The surface conductive coating can improve the weldability and oxidation resistance of the photovoltaic welding ribbon, and form an ohmic contact with the grid lines of the solar cell, transferring the current generated by the solar cell to the conductive substrate.

[0037] However, currently, photovoltaic solder ribbons and solar cells are typically interconnected using circular solder ribbons. However, the circular surface of these ribbons has poor adhesion to the solar cell grid lines, resulting in a relatively small contact area. Furthermore, when a circular solder ribbon is bent, the surface stress distribution is not uniform, easily leading to high stress concentration at the bending point.

[0038] Based on this, this application discloses a photovoltaic ribbon and a photovoltaic module, which aim to improve the photoelectric conversion efficiency of the photovoltaic module by increasing the contact area between the photovoltaic ribbon and the grid lines on the solar cell. Specifically, by constructing at least one plane on the surface of the conductive coating of the photovoltaic ribbon, the adhesion between the photovoltaic ribbon and the solar cell is improved. This increases the contact area between the conductive coating of the photovoltaic ribbon and the grid lines on the solar cell, thereby improving the adhesion between the photovoltaic ribbon and the solar cell and forming a good ohmic contact, which is beneficial for obtaining higher photoelectric conversion efficiency.

[0039] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0040] Please see Figure 1 , Figure 1This is a schematic diagram of the cross-section of the photovoltaic solder ribbon 1 disclosed in an embodiment of this application. This application discloses a photovoltaic solder ribbon 1, which is applied to a photovoltaic module 2 (see details). Figure 6 The photovoltaic module 2 includes multiple solar cells 13, and the photovoltaic ribbon 1 is configured to connect two adjacent solar cells 13 to achieve electrical connection between the two adjacent solar cells.

[0041] The photovoltaic ribbon 1 of this application includes a conductive substrate 11 and a conductive coating 12. The conductive substrate 11 is used to transmit current obtained from the conductive coating 12. The conductive coating 12 covers the outer periphery of the conductive substrate 11 and is configured to have at least one plane 121. The at least one plane 121 is configured to be connected to the grid line 131 of the solar cell 13 to conduct current to the conductive substrate 11.

[0042] By altering the cross-sectional shape of the conductive coating 12 along its length, specifically by ensuring the conductive coating has at least one plane 121, the contact area between the conductive coating 12 and the grid lines 131 of the solar cell 13 can be increased. This increased contact area allows for a tighter and more uniform connection between the coating and the grid lines 131, reducing resistance at the contact point and thus lowering current loss through the connected portion. Consequently, under the same photoelectric conversion efficiency, the photovoltaic module 2 can receive more current.

[0043] In addition, the presence of the conductive coating 12 can effectively isolate the conductive substrate from the external environment, prevent the conductive substrate from being oxidized and corroded, so that the photovoltaic module 2 can maintain stable performance even under harsh environmental conditions.

[0044] In some embodiments, the conductive coating 12 is configured in a cross-section along its own length as at least one of a polygon, an arc, a semicircle, or an oval.

[0045] Compared to the photovoltaic ribbon 1 with a circular cross-section, the conductive coating 12 has a cross-section constructed as a polygon, an arc, a semicircle, or an oval shape. This increases the contact area when its planar portion contacts the grid lines 131 of the solar cell 13. A larger contact area allows more electrons to transfer smoothly between the cell and the ribbon, more effectively collecting the current generated by the solar cell, reducing current loss during transmission, and thus improving conductivity.

[0046] It is understood that the cross-sectional shape of the conductive plating layer 12 is not limited to the above-mentioned types. As long as there is a plane 121 used to increase the contact area, it is not specifically limited in this embodiment.

[0047] It is understood that the aforementioned polygons may include, but are not limited to, rectangles, trapezoids, etc. This application will use a trapezoidal cross-sectional shape of the conductive coating as an example for further explanation.

[0048] Please see Figure 2 and Figure 3 , Figure 2 This is a schematic diagram of the structure of the photovoltaic ribbon 1 connected to the solar cell as disclosed in the embodiments of this application. Figure 3 yes Figure 2 A magnified view of a portion of point A in the middle.

[0049] In some embodiments, the conductive coating 12 has a trapezoidal cross-section along its length. Optionally, the trapezoid may include, but is not limited to, a right trapezoid, an isosceles trapezoid, etc. The trapezoidal cross-section of the conductive coating along its length means that the cross-section of the conductive coating has at least two planes, resulting in a larger contact area when connected to the grid lines of the solar cell.

[0050] Optionally, the trapezoid includes a top side 122 and a bottom side 123 that are parallel to each other, and two hypotenuses 124 connected between the top side 122 and the bottom side 123, wherein the angle between at least one hypotenuse 124 and the bottom side 123 is in the range of 45° to 55°.

[0051] The length of the top edge 122 is less than the length of the bottom edge 123, and the bottom edge 123 is configured to connect to the grid line 131 of the solar cell 13.

[0052] In this way, the photovoltaic ribbon 1 and the grid lines 131 of the photovoltaic cell can obtain a larger contact area, reducing the resistance of the contact portion and improving the conductivity. At the same time, considering the light reflection path and the changing weather throughout the day, at least one inclined side 124 forming a 45° to 55° angle with the bottom edge 123 can be used to reflect more light onto the solar cell 13. Therefore, the solar cell 13 can achieve a higher light utilization rate under the same illumination environment, thereby generating more current and improving the power generation efficiency of the solar cell 13.

[0053] In some embodiments, the conductive coating 12 is made of a zinc-aluminum alloy. Compared to tin-lead alloys used for high-temperature (e.g., temperatures of 200°C and above) welding, zinc-aluminum alloys have lower density, higher strength, and good room-temperature mechanical properties and wear resistance. Furthermore, because zinc-aluminum alloys can form a dense alumina layer on their surface through contact with air, they exhibit better corrosion resistance in the atmosphere, which is beneficial for improving the operational stability of the photovoltaic module 2.

[0054] Furthermore, this application uses a zinc-aluminum alloy instead of a tin-lead alloy. In the fabrication of the conductive coating 12, since the melting point of the zinc-aluminum alloy is between 700 and 800°C, and pure copper with a melting point of 1083.4°C is used as the conductive substrate 11, the conductive coating 12 can be formed on the surface of the conductive substrate 11 using a hot-casting method. However, when using a tin-lead alloy as the conductive coating 12, electroplating and chemical plating are required to adhere the tin-lead alloy to the surface of the conductive substrate 11. Relatively speaking, the hot-casting method is simpler and has more controllable process costs.

[0055] In addition, the recycling and reuse technologies for zinc-aluminum alloys are relatively mature. Their waste can be effectively recycled and remelted into new alloy materials, which not only helps to reduce the exploitation of natural resources, but also reduces energy consumption and environmental pollution in the production process.

[0056] In some embodiments, the thickness of the conductive coating 12 is between 0.03 mm and 0.08 mm. Within this thickness range, the conductive coating maintains good conductivity. Since the conductivity of the conductive coating is lower than that of the conductive substrate 11, this thickness range allows the conductive coating to increase the contact area with the grid lines 131 while maintaining low resistance, reducing power loss as current passes through the conductive coating 12, and ensuring the power generation efficiency of the photovoltaic module 2.

[0057] It is understood that the thickness of the conductive coating can be 0.04mm-0.06mm, or 0.03mm-0.07mm, etc. For example, the thickness can be 0.04mm, 0.05mm, 0.06mm, 0.07mm, etc.

[0058] Please see Figure 4 , Figure 4 This is a schematic diagram of the structure of the photovoltaic module 2 disclosed in this application, in which adjacent cells are connected by photovoltaic ribbons 1.

[0059] In some embodiments, the photovoltaic module 2 includes a plurality of solar cells 13 and a photovoltaic ribbon 1, the photovoltaic ribbon 1 being used to electrically connect two adjacent solar cells 13.

[0060] The photovoltaic ribbon 1 can collect the current generated by each solar cell 13 and transmit it to the busbar 27 of the photovoltaic module 2. The use of the photovoltaic ribbon can reduce the current transmission loss between solar cells, which is beneficial to improving the power generation efficiency of the photovoltaic module 2.

[0061] In addition, the photovoltaic ribbon 1 not only serves as an electrical connection but also provides mechanical support for the solar cell 13. During the production and use of the photovoltaic module 2, the photovoltaic ribbon 1 can prevent the solar cell 13 from shifting, bending, or breaking due to external forces, thereby improving the mechanical stability and durability of the photovoltaic module 2.

[0062] Please see Figure 5 , Figure 5 yes Figure 4 A magnified view of a portion at point B. In some embodiments, the photovoltaic module 2 further includes an adhesive layer 21, through which the photovoltaic ribbon 1 is bonded to the solar cell 13.

[0063] In some embodiments, the adhesive layer 21 of the photovoltaic module 2 is disposed between the photovoltaic ribbon 1 and the silicon wafer surface of the solar cell 13.

[0064] It is understandable that the adhesive layer 21 can be made of either thermosetting silicone or photosetting silicone.

[0065] Since the conductive coating 12 of the photovoltaic ribbon 1 in this application is made of zinc-aluminum alloy, an aluminum oxide thin film will be formed on the surface of the conductive coating 12 after it comes into contact with air. The aluminum oxide thin film can chemically bond with the Si-O (silicon-oxygen) in the adhesive layer 21, and the photovoltaic ribbon 1 and the adhesive layer 21 can be firmly bonded under the action of chemical bonding.

[0066] To reduce the reflectivity of the silicon wafer surface of solar cell 13, a texturing process is typically performed to form a micro-textured structure on the silicon wafer surface. This micro-textured structure provides a large contact area with the silicone adhesive. Simultaneously, the surface energy of the silicon wafer increases after texturing and cleaning, and it becomes rich in elements such as silicon and oxygen, providing chemical groups for silicone adhesion. The silicone material of adhesive layer 21 has a three-dimensional network structure, and the active groups such as silanol groups (-Si-OH) in the silicone molecules can chemically react with the micro-textured structure on the surface of solar cell 13.

[0067] In this way, the silicon wafer of solar cell 13 can not only physically adsorb through close contact between the active groups of the silicone and the surface microtexture structure, allowing the silicone to penetrate deep into the uneven surface of the microtexture structure and form a mechanical anchor after curing, thus enhancing adhesion, but also chemically react with the silicon atoms of the microtexture structure on the surface of solar cell 13 through the active groups in the silicone to form stable Si-Si bonds. This chemical bonding provides a high-strength and high-stability bond between the silicone and solar cell 13, thereby ensuring a firm connection between the photovoltaic ribbon 1 and the solar cell 13.

[0068] In some embodiments, there is no welding layer between the photovoltaic module 2 and the solar cell 13. As mentioned above, the conductive plating layer 12 of this application is made of zinc-aluminum alloy and the photovoltaic ribbon 1 with a cross-section constructed with a straight edge, and the adhesive layer 21 is made of silicone. This allows the photovoltaic ribbon 1 to be stably fixed to the solar cell 13 without high-temperature welding. This not only simplifies the connection method, but also avoids many disadvantages of high-temperature welding, such as: easy to cause poor welding, over-welding, microcracks, increased breakage rate of solar cell 13, and affecting the performance of solar cell 13.

[0069] Under normal circumstances, in order to connect the photovoltaic ribbon 1 to the solar cell 13, it is necessary to weld the photovoltaic ribbon 1 to the main grid of the solar cell 13 through the conductive plating layer 12 to ensure a stable connection. However, in this embodiment, since a stable connection between the photovoltaic ribbon 1 and the solar cell 13 can be achieved solely through the adhesive layer 21, the welding layer can be avoided. Therefore, it is not necessary for the surface of the solar cell 13 to have the main grid lines 131 printed on it. The gridless solar cell 13 effectively saves the use of conductive paste for printing the main grid, thereby achieving cost savings.

[0070] Please see Figure 6 , Figure 6 This is a schematic diagram of the overall structure of photovoltaic module 2.

[0071] The photovoltaic module 2 also includes: a frame 22, a glass cover 23, an encapsulation layer 24, a solar cell 13, a back sheet 25, and a junction box 26 arranged sequentially along the thickness direction of the solar cell.

[0072] The glass cover plate 23 is spaced above the back plate 25 along the thickness direction of the back plate 25, forming a sandwich space between the glass cover plate and the back plate 25 in the thickness direction of the back plate 25. This sandwich space can be used to hold the solar cell. The use of glass cover plates not only ensures that light can shine on the surface of the solar cell 13 to complete the photoelectric conversion, but also provides physical protection for the solar cell 13, preventing physical damage such as external impact, mechanical vibration, and impact from gravel.

[0073] Furthermore, the solar cell 13 is encapsulated by an encapsulation layer 24 inside the interlayer space. The encapsulation layer 24 can be made of at least one of TPO (Thermoplastic Olefin) or POE (Polyolefin elastomer).

[0074] The encapsulation material can prevent the solar cell 13 from direct contact with the external environment, prevent harmful substances such as water vapor, oxygen, dust, and salt spray from corroding the solar cell 13, avoid chemical reactions such as oxidation and corrosion of the solar cell 13, and maintain the stability of the electrical performance of the solar cell 13.

[0075] Junction box 26 is located on the side of back panel 25 away from solar cell 13. Junction box 26 is also provided with busbar 27, which is used to connect to photovoltaic ribbon 1 and can collect the current generated by solar cell 13.

[0076] During operation, there is a possibility that current may flow back into the solar cell 13, causing it to become a load. This can lead to problems such as localized heat generation, hot spots, localized aging, and damage to the crystal structure of the solar cell 13. Therefore, a diode 28 can be installed inside the junction box 26. The diode 28 can prevent current from flowing back into the solar cell 13 during the operation of the photovoltaic module 2, thus preventing the solar cell 13 from becoming a load.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A photovoltaic welding strip, characterized in that, The photovoltaic ribbon is used in a photovoltaic module, the photovoltaic module including multiple solar cells, and the photovoltaic ribbon is configured to connect two adjacent solar cells. The photovoltaic ribbon includes: Conductive substrate; A conductive coating is applied to the outer periphery of the conductive substrate. The conductive coating is configured to have at least one plane, which is configured to connect to the grid lines of the solar cell to conduct current to the conductive substrate.

2. The photovoltaic welding strip according to claim 1, characterized in that, The conductive coating is configured in a cross-section along its length as at least one of polygon, arc, semicircle, and oval.

3. The photovoltaic welding strip according to claim 2, characterized in that, The conductive coating has a trapezoidal cross-section along its length.

4. The photovoltaic welding strip according to claim 3, characterized in that, The trapezoid includes a top side and a bottom side that are parallel to each other, and two inclined sides connected between the top side and the bottom side, wherein the angle between at least one inclined side and the bottom side is in the range of 45° to 55°. The length of the top edge is less than the length of the bottom edge, and the bottom edge is configured to connect to the grid lines of the solar cell.

5. The photovoltaic welding strip according to any one of claims 1-4, characterized in that, The conductive coating is made of zinc-aluminum alloy.

6. The photovoltaic welding strip according to claim 5, characterized in that, The thickness of the conductive coating is from 0.03 mm to 0.08 mm.

7. A photovoltaic module, characterized in that, The photovoltaic module includes: Multiple solar cells; The photovoltaic ribbon as described in any one of claims 1-6 is used to electrically connect two adjacent solar cells.

8. The photovoltaic module according to claim 7, characterized in that, The photovoltaic module also includes an adhesive layer, through which the photovoltaic ribbon is bonded to the solar cell.

9. The photovoltaic module according to claim 7, characterized in that, The adhesive layer of the photovoltaic module is disposed between the photovoltaic ribbon and the silicon wafer surface of the solar cell.

10. The photovoltaic module according to claim 7, characterized in that, No welding layer is provided between the photovoltaic module and the solar cell.

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