Photovoltaic module and preparation method thereof

Abstract

The invention discloses a photovoltaic module and a preparation method thereof, and relates to the technical field of solar cells, and the photovoltaic module comprises a plurality of photovoltaic cells, the light receiving surfaces of the photovoltaic cells are provided with an auxiliary grid array, and the auxiliary grid array comprises a plurality of parallel grid lines; the plurality of flexible interconnection strips are used for connecting adjacent photovoltaic cells in series; the flexible interconnection strips are directly and electrically connected to the auxiliary grid arrays on the light receiving surfaces of the adjacent photovoltaic battery pieces through a plurality of discrete welding points; and a mechanical stress release structure is formed on the flexible interconnection strip in a section between two adjacent battery pieces. According to the photovoltaic module provided by the invention, the plurality of auxiliary grids are electrically connected by adopting the flexible interconnection strips, so that the overall silver paste consumption is reduced by 30%-50%, the flexible connection between the photovoltaic cells is realized through the mechanical stress release structures arranged in the flexible interconnection strips, the anti-bending angle can reach-30 degrees to 30 degrees, and the anti-bending performance of the photovoltaic module is improved. And the stress generated by thermal expansion and cold contraction of the assembly can be relieved, and the fragmentation risk of the photovoltaic battery piece is reduced.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a photovoltaic module and its preparation method. Background Technology

[0002] The electrode design of photovoltaic cells has long faced the challenge of balancing efficiency, cost, and reliability. While current mainstream super-multi-busbar technology has undergone continuous optimization, it still has inherent limitations: finer busbars reduce shading but increase resistance; the amount of silver paste used drives up costs, making it difficult to adapt to rising raw material prices; and it is prone to microcracks when supporting ultra-thin silicon wafers. To address these issues, the industry has proposed zero-busbar technology, which eliminates the front-side busbar and uses high-density fine sub-busbars to collect current, directly connecting the sub-busbars to a flexible interconnect structure for current transmission. However, in practical applications, this technology still needs to solve key problems such as how to achieve a highly reliable, low-loss electrical connection between the sub-busbars and the interconnect structure, and how to construct a new interconnect architecture at the module level that combines flexibility and mechanical stability. Summary of the Invention

[0003] The main purpose of this application is to propose a photovoltaic module and its manufacturing method, which aims to solve the problem that existing photovoltaic modules cannot simultaneously possess flexibility and mechanical stability.

[0004] To achieve the above objectives, in a first aspect, this application proposes a photovoltaic module, comprising: a plurality of photovoltaic cells, wherein the light-receiving surface of the photovoltaic cells is provided with a sub-grid array, the sub-grid array comprising a plurality of mutually parallel grid lines;

[0005] Multiple flexible interconnecting strips are used to connect adjacent photovoltaic cells in series; The flexible interconnect strip is directly and electrically connected to the sub-gate array on the light-receiving surface of the adjacent photovoltaic cell through multiple discrete welding points; The flexible interconnect strip has a mechanical stress relief structure formed in the section located between two adjacent battery cells.

[0006] In some embodiments, the mechanical stress relief structure is a periodic bending hinge formed on the flexible interconnect strip, wherein the radius of curvature of a single bending hinge is 1 to 2 mm.

[0007] In some embodiments, the flexible interconnect strip is a flat metal strip with a thickness of 0.08~0.15 mm and a width of 0.3~0.5 mm.

[0008] In some embodiments, the flexible interconnect strip is provided with a tin-plated layer; The thickness of the tin plating layer is 5~8 μm.

[0009] In some embodiments, the width of the gate line is 15~25 μm, and the spacing between adjacent gate lines is 0.8~1.2 mm.

[0010] In some embodiments, the flexible interconnect strip is connected to the sub-gate array via a first preset number of welding points; the diameter of the welding points is 0.2-0.3 mm.

[0011] In some implementations, the first preset quantity is 8 to 12; and / or, The spacing between adjacent welding points matches the grid line spacing.

[0012] In some embodiments, the gap between adjacent photovoltaic cells is 0.5 to 1 mm.

[0013] Secondly, this application also proposes a method for preparing the photovoltaic module proposed in this application, comprising: Multiple photovoltaic cells are provided, wherein a sub-grid array is fabricated on the light-receiving surface of the photovoltaic cells; Multiple flexible interconnecting strips are provided, and mechanical stress relief structures are formed at preset positions on the flexible interconnecting strips; The flexible interconnect strips are directly welded to the sub-grid array at multiple discrete welding points using infrared spot welding technology to produce a photovoltaic module.

[0014] In some embodiments, the infrared spot welding temperature is 220~250℃, the welding pressure is 0.1~0.2MPa, and the contact resistance between the welding point and the sub-gate array is ≤5 mΩ.

[0015] The photovoltaic module proposed in this application uses a combination of high-density fine sub-busbars and flexible interconnect strips to replace the traditional combination of coarse main busbars and wide solder strips, shortening the current path, reducing shading, and improving conversion efficiency by 0.5% to 1%. Simultaneously, by using flexible interconnect strips to electrically connect multiple sub-busbars, the overall silver paste usage is reduced by 30% to 50%. Furthermore, the mechanical stress relief structure set in the flexible interconnect strips enables flexible connections between photovoltaic cells, with a bending angle resistance of -30° to 30°, and can alleviate the stress generated by thermal expansion and contraction of the module, reducing the risk of photovoltaic cell breakage and increasing the mechanical load tolerance of the photovoltaic module to 5400 Pa.

[0016] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0017] 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 only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 A front view of the photovoltaic module provided in this application; Figure 2 A top view of the photovoltaic module provided in this application.

[0019] Icon labels: 100. Photovoltaic module; 1. Photovoltaic cell; 11. Sub-grid array; 111. Grid line; 2. Flexible interconnect strip; 21. Mechanical stress relief structure; 22. Welding area; 23. Reinforcing rib; 3. Welding point.

[0020] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] 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 a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0022] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0023] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution that simultaneously satisfies A and B. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0024] Improving photoelectric conversion efficiency, reducing manufacturing costs, and ensuring long-term reliability are the core goals of photovoltaic technology development. However, electrode design has always faced a triangular dilemma where efficiency, cost, and reliability are difficult to optimize in a coordinated manner. As the current mainstream technology, super multi-busbar technology has approached its physical and material limits through meticulous improvements to the busbar, and its inherent contradictions are becoming increasingly prominent: First, there is a contradiction between shading loss and conductivity efficiency. Reducing the busbar width can reduce the shading area, but the simultaneous reduction in the conductive cross-sectional area will lead to a significant increase in series resistance, which in turn increases power loss; it is difficult to balance the two. Second, there is a contradiction between the high cost of silver paste and the necessary performance. The busbar is the main component of the battery's silver paste consumption, accounting for approximately 15% to 20% of the non-silicon cost of the cell. With the continuous rise in silver prices, this part of the cost pressure is enormous, but the busbar is indispensable for current collection. Finally, there is a contradiction between mechanical strength and the trend towards thinner wafers. To reduce silicon consumption, silicon wafers are rapidly developing towards thinner wafers (thickness ≤120μm). Traditional busbars serve as the main welding support points for solder strips, and their mechanical support is crucial for thin silicon wafers. However, the design of finer and denser busbars has weakened the local support strength, increasing the risk of microcracks in the cells during subsequent manufacturing and module operation.

[0025] To fundamentally overcome the aforementioned bottlenecks, the industry has begun exploring "busbar-free" solutions, namely zero-busbar technology. This technology completely eliminates the main busbar electrodes on the front of the solar cell, retaining only optimized, high-density fine sub-busbars to form a "super-collecting network" for efficient collection of photocurrent. At the interconnect end, extremely fine flexible solder strips are used to directly connect to the dense sub-busbars. These solder strips simultaneously handle current collection and transmission as well as cell interconnection, thus achieving a paradigm shift from "busbar-dependent rigid interconnection" to "busbar-free flexible interconnection." However, the specific implementation of this emerging technology, especially how to achieve high-reliability, low-loss direct interconnection of sub-busbars, and how to design module structures adapted to flexible interconnection to ensure mechanical performance, still require in-depth research and improvement.

[0026] Based on the above issues, please refer to Figure 1 and Figure 2 In a first aspect, embodiments of this application propose a photovoltaic module 100, comprising multiple photovoltaic cells 1 and multiple flexible interconnecting strips 2. The photovoltaic cells 1 have a sub-grid array 11 on their light-receiving surface, the sub-grid array 11 comprising multiple parallel grid lines 111. The flexible interconnecting strips 2 are used to connect adjacent photovoltaic cells 1 in series. Specifically, the flexible interconnecting strips 2 are directly and electrically connected to the sub-grid array 11 on the light-receiving surface of the photovoltaic cells 1 through multiple discrete welding points 3. The flexible interconnecting strips 2 include a mechanical stress relief structure 21 and a welding area 22, the mechanical stress relief structure 21 being located between two adjacent photovoltaic cells 1.

[0027] Understandably, the sub-busbar array 11 in the photovoltaic module 100 is located on the light-receiving surface of the photovoltaic cell 1 and is used to collect the current (photogenerated carriers) generated by the photovoltaic cell 1 when excited by light. The flexible interconnect strip 2 is electrically connected to the sub-busbar array 11 through multiple discrete welding points 3, replacing the traditional main busbar, and is used to collect the current in the sub-busbar array 11. It also serves to replace the traditional solder strip to connect multiple photovoltaic cells 1.

[0028] The photovoltaic module 100 in this embodiment of the application, on the one hand, shortens the current path and reduces shading by using a combination of high-density grid lines 111 and flexible interconnect strips 2 instead of the traditional combination of thick main grid and wide solder strips, thereby improving the conversion efficiency by 0.5% to 1%. On the other hand, the mechanical stress relief structure 21 set in the flexible interconnect strips 2 realizes the flexible connection between photovoltaic cells 1, with a bending angle resistance of -30° to 30°, and can alleviate the stress generated by thermal expansion and contraction of the module, reducing the risk of breakage of photovoltaic cells 1, and improving the mechanical load tolerance of the photovoltaic module 100 to 5400 Pa.

[0029] In some embodiments, the mechanical stress relief structure 21 is a periodic bending hinge formed on the flexible interconnecting strip 2, with the radius of curvature of a single bending hinge being 1 to 2 mm. For example, the radius of curvature of the bending hinge can be 1 mm, 1.2 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.8 mm, or 2 mm, etc.

[0030] By setting the radius of curvature of the bending hinge to 1~2 mm, the flexible interconnect strip 2 can be bent to a certain extent, thereby enabling the photovoltaic module 100 to have a bending angle of -30°~30°.

[0031] In some embodiments, the flexible interconnecting strip 2 is a flat metal strip with a thickness of 0.08~0.15 mm and a width of 0.3~0.5 mm. For example, the thickness of the flat metal strip can be 0.08 mm, 0.1 mm, 0.12 mm, or 0.14 mm, etc., and the width can be 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, or 0.5 mm, etc.

[0032] By setting the thickness of the flexible interconnect strip 2 to 0.08~0.15 mm, it is ensured that the flexible interconnect strip 2 has sufficient conductive cross-sectional area and mechanical strength. Setting the width to 0.3~0.5 mm can minimize the light-blocking area.

[0033] In some embodiments, the flexible interconnect strip 2 is provided with a tin-plated layer, the thickness of which is 5-8 μm. For example, the thickness of the tin-plated layer can be 5 μm, 6 μm, 7 μm, or 8 μm. During welding, the molten tin layer can quickly wet and alloy the silver electrode of the battery, forming a low-resistance, stable transition layer, ensuring that current can flow efficiently from the battery to the copper core. At the same time, tin has a low melting point, much lower than that of copper and silver. This allows welding to be completed at a relatively low temperature and in a short time, greatly reducing the thermal shock to the battery cell and avoiding high-temperature damage to the silicon wafer (photovoltaic cell) or PN junction, which is crucial for thinning.

[0034] In some embodiments, the flexible interconnect strip 2 also includes a reinforcing rib 23, which connects two adjacent flexible interconnect strips 2 to further improve the longitudinal structural stability of the flexible interconnect strip 2, thereby improving the bending resistance of the photovoltaic module 100.

[0035] In some embodiments, the width of the gate line 111 is 15~25 μm, for example, the width of the gate line 111 can be 15 μm, 20 μm or 25 μm. The spacing between adjacent gate lines 111 is 0.8~1.2 mm, for example, the spacing between adjacent gate lines 111 can be 0.8 mm, 0.9 mm, 1 mm, 1.1 mm or 1.2 mm. Multiple parallel gate lines 111 form a "super collection network", which can efficiently and with low loss collect photocurrent without a main gate. At the same time, the thinner width of the gate line 111 also minimizes light-shielding loss and silver paste consumption.

[0036] In some embodiments, the flexible interconnecting strip 2 is connected to the sub-grid array 11 via a first preset number of welding points 3, the diameter of which is 0.2 to 0.3 mm. For example, the diameter of the welding point 3 is 0.2 mm, 0.25 mm, or 0.3 mm, etc. Further, the first preset number is 8 to 12, and / or the spacing between adjacent welding points 3 is the same as the spacing of the grid lines 111.

[0037] By using discretely set welding points instead of traditional continuous surface welding, the rigid constraints caused by long weld seams are avoided, increasing the bending resistance of the photovoltaic module 100. Setting the spacing between adjacent welding points 3 to be the same as the spacing of the grid lines 111 makes the connection force distribution of the flexible interconnect strip 2 on the photovoltaic cell 1 more uniform, and works in conjunction with the mechanical stress relief structure 21 to further disperse stress and improve crack resistance.

[0038] In some embodiments, the gap between adjacent photovoltaic cells 1 is 0.5 to 1 mm. For example, the gap between adjacent photovoltaic cells 1 can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1 mm, etc.

[0039] By using the flexible interconnecting strip 2 in this embodiment to connect the photovoltaic cells 1, the gap between adjacent photovoltaic cells 1 is effectively shortened, the proportion of the effective power generation area of ​​the photovoltaic module 100 in the overall area is increased, and the final output power of the photovoltaic module 100 can be improved.

[0040] This application also proposes a method for manufacturing a photovoltaic module as described above, comprising: S1. Provide multiple photovoltaic cells, with a sub-grid array fabricated on the light-receiving surface of the photovoltaic cells; S2. Provide multiple flexible interconnecting strips to form a mechanical stress relief structure at preset positions of the flexible interconnecting strips; S3. Using infrared spot welding technology, flexible interconnecting strips are directly welded to the sub-grid array at multiple discrete welding points to produce photovoltaic modules.

[0041] In some embodiments, the welding temperature for infrared spot welding is 220~250℃. For example, the welding temperature for infrared spot welding can be 220℃, 230℃, 240℃, or 250℃, etc. The welding pressure is 0.1~0.2 MPa. For example, the welding pressure can be 0.1 MPa, 0.15 MPa, or 0.2 MPa, etc. The contact resistance between the weld point and the sub-gate array is ≤5 mΩ.

[0042] The above description is merely an exemplary embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the technical concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A photovoltaic module, characterized in that, The photovoltaic module includes: Multiple photovoltaic cells, wherein the light-receiving surface of each photovoltaic cell is provided with a sub-grid array, the sub-grid array comprising multiple parallel grid lines; Multiple flexible interconnecting strips are used to connect adjacent photovoltaic cells in series; The flexible interconnect strip is directly and electrically connected to the sub-gate array on the light-receiving surface of the adjacent photovoltaic cell through multiple discrete welding points; The flexible interconnect strip has a mechanical stress relief structure formed in the section located between two adjacent photovoltaic cells.

2. The photovoltaic module as described in claim 1, characterized in that, The mechanical stress relief structure is a periodic bending hinge formed on the flexible interconnecting strip, and the radius of curvature of a single bending hinge is 1~2 mm.

3. The photovoltaic module as described in claim 1, characterized in that, The flexible interconnecting strip is a flat metal strip with a thickness of 0.08~0.15 mm and a width of 0.3~0.5 mm.

4. The photovoltaic module as described in claim 1, characterized in that, The flexible interconnecting strip is provided with a tin-plated layer; The thickness of the tin plating layer is 5~8 μm.

5. The photovoltaic module as described in claim 1, characterized in that, The width of the gate line is 15~25 μm, and the spacing between adjacent gate lines is 0.8~1.2 mm.

6. The photovoltaic module as described in claim 1, characterized in that, The flexible interconnect strip is connected to the sub-gate array through a first preset number of welding points; the diameter of the welding points is 0.2~0.3 mm.

7. The photovoltaic module as described in claim 6, characterized in that, The first preset quantity is 8 to 12; and / or, The spacing between adjacent welding points matches the grid line spacing.

8. The photovoltaic module as described in claim 1, characterized in that, The gap between adjacent photovoltaic cells is 0.5~1 mm.

9. A method for preparing a photovoltaic module according to any one of claims 1 to 8, characterized in that, include: Multiple photovoltaic cells are provided, wherein a sub-grid array is fabricated on the light-receiving surface of the photovoltaic cells; Multiple flexible interconnecting strips are provided, and mechanical stress relief structures are formed at preset positions on the flexible interconnecting strips; The flexible interconnect strips are directly welded to the sub-grid array at multiple discrete welding points using infrared spot welding technology to produce a photovoltaic module.

10. The method for preparing a photovoltaic module as described in claim 9, characterized in that, The infrared spot welding temperature is 220~250℃, the welding pressure is 0.1~0.2 MPa, and the contact resistance between the welding point and the sub-gate array is ≤5 mΩ.

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