Photovoltaic module

Abstract

The embodiment of the present application relates to the photovoltaic field, and provides a photovoltaic module, comprising: a plurality of cell strings, the cell string comprising a plurality of cell pieces connected in series, the first cell piece connected in series in the cell string is a first cell piece, the last cell piece connected in series in the cell string is a second cell piece, a plurality of first cell pieces are connected through a first solder strip, a plurality of second cell pieces are also connected through the first solder strip, and the extension direction of the first solder strip is parallel to the extension direction of the first fine grid line in the cell piece. The photovoltaic module provided by the embodiment of the present application connects two cell strings which need to be connected in series through the solder strip interconnection strip perpendicular to the main grid at the head and tail cell pieces of the cell string, so that the head and tail cell pieces of the cell string can cancel the bus bar design, and the problem that the series connection mode of the cell string of the photovoltaic module in the prior art can limit the power generation area of the cell piece or easily cause the risk of hidden cracks / chips is solved.

Description

Technical Field

[0001] This application relates to the field of photovoltaics, and in particular to a photovoltaic module. Background Technology

[0002] In photovoltaic (PV) module cell strings, busbars are typically used to connect the beginning and end of the cell. In related technologies, the busbars are usually placed outside the cells or on the back of the cells, hidden from view on the front. Placing the busbars outside the cells occupies a limited area of ​​the module, thus limiting the power generation area of ​​the cells. Placing the busbars on the back of the cells increases the risk of microcracks / fractures during manufacturing and load-bearing processes. Summary of the Invention

[0003] This application provides a photovoltaic module that at least addresses the problem in the prior art where the series connection of photovoltaic module cell strings limits the power generation area of ​​the cells or easily leads to microcracks / breakage risks.

[0004] According to some embodiments of this application, one aspect of this application provides a photovoltaic module, including: a plurality of cell strings, each cell string including a plurality of cells connected in series, the first cell connected in series in the cell string being a first cell, the last cell connected in series in the cell string being a second cell, the plurality of first cells being connected by a first solder strip, and the plurality of second cells being connected by the first solder strip, wherein the extension direction of the first solder strip is parallel to the extension direction of the first fine grid lines in the cell.

[0005] In some embodiments, both the first and second solar cells have multiple main grid lines of different polarities, and the first solder strip is connected to the main grid line of the first polarity.

[0006] In some embodiments, the main grid line of the first polarity has multiple solder joints, and the first solder strip is connected to the main grid line of the first polarity through the solder joints.

[0007] In some embodiments, the first solar cell is connected to an adjacent solar cell via a second solder strip, the second polarity main grid line on the first solar cell is connected to the second solder strip, the second solder strip covers the second polarity main grid line, and the photovoltaic module further includes an insulating layer located between the first solder strip and the second solder strip.

[0008] In some embodiments, the insulating layer includes a plurality of intermittently arranged insulating strips, one of the insulating strips covering one of the second solder strips, the length of the insulating strip in a first direction being greater than or equal to the length of the second solder strip in the first direction, the first direction being the arrangement direction of the battery string.

[0009] In some embodiments, the length of the insulating strip in a first direction is positively correlated with the spacing between two adjacent main grid lines.

[0010] In some embodiments, the length of the insulating strip in the first direction is 10mm ± 5mm.

[0011] In some embodiments, the length of the first solder strip in the first direction is 0.6 mm to 2.0 mm, the length of the first solder strip in the second direction is 0.05 mm to 0.20 mm, the first direction is the arrangement direction of the battery string, the second direction is the direction perpendicular to the first surface of the battery string, and the first surface is the surface with the largest area of ​​the battery string.

[0012] In some embodiments, the nth solar cell and the (n+1)th solar cell are connected in series via a third solder strip, and the (n+1)th solar cell and the (n+2)th solar cell are connected in series via a fourth solder strip. The third solder strip is connected to the first fine grid line, and the fourth solder strip is connected to the second fine grid line of the solar cell. The first fine grid line and the second fine grid line have different polarities, and n is a positive integer.

[0013] In some embodiments, the solar cells each have multiple main grid lines of different polarities.

[0014] The technical solution provided in this application has at least the following advantages: The photovoltaic module includes multiple cell strings, each cell string including multiple cells connected in series. The first cell connected in series in a cell string is a first cell, and the last cell connected in series in a cell string is a second cell. Multiple first cells are connected by a first solder strip, and multiple second cells are also connected by a first solder strip. The extension direction of the first solder strip is parallel to the extension direction of the first fine grid line in the cell. The photovoltaic module provided in this application connects two cell strings that need to be connected in series by designing solder strip interconnects perpendicular to the main grid at the beginning and end of the cell string. This eliminates the need for busbar design at the beginning and end of the cell string, increasing the power generation area of ​​the cell. Furthermore, the first solder strip is evenly distributed at the grid position of the cell, away from the easily cracked edge area, reducing the risk of microcracks / fractures. This solves the problem in the prior art where the series connection method of photovoltaic module cell strings limits the power generation area of ​​the cell or easily leads to microcracks / fractures. Attached Figure Description

[0015] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the drawings in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional art, 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.

[0016] Figure 1 A schematic diagram of the structure of a photovoltaic module according to an embodiment of this application is shown;

[0017] Figure 2 A schematic diagram of the structure of another photovoltaic module provided according to an embodiment of this application is shown.

[0018] The above figures include the following reference numerals:

[0019] 10. Battery string; 11. Battery cell; 12. First solder strip; 13. Second solder strip; 14. Insulating layer; 141. Insulating strip. Detailed Implementation

[0020] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0023] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0024] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0025] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0026] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0027] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may be present therein. Moreover, when a component such as a layer, film, region, or plate is "directly located" on another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it indicates that no other components are located therein.

[0028] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "part" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0029] As described in the background section, in existing photovoltaic module manufacturing technologies, busbars are typically placed at the beginning and end of the module to connect the first and last cells of adjacent strings in order to achieve electrical series connection between multiple strings of cells. One conventional approach is to place the busbars in the frame area outside the cells, but this method occupies the effective area of ​​the module and reduces the light absorption efficiency per unit area. With the industry's pursuit of high-density packaging and full-screen design, this structure has been gradually marginalized. Another mainstream approach is to place the busbars on the back of the cells. Although this can improve the aesthetics of the front and increase the light-receiving area, during the cell manufacturing process and mechanical load testing after module packaging, the contact area between the busbars and the cells is prone to microcracks or cell breakage due to stress concentration, which significantly affects the reliability and long-term durability of the module. At the same time, the welding process of the back-side busbars is complex, the material cost is high, and there are potential hot spots and electrical mismatch risks.

[0030] To address the problem that the series connection method of photovoltaic module cells in the prior art limits the power generation area of ​​the cells or is prone to microcracks / breakage, the embodiments of this application provide a photovoltaic module.

[0031] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0032] Figure 1 This is a schematic diagram of the structure of a photovoltaic module according to an embodiment of this application. Figure 1As shown, the photovoltaic module includes: multiple cell strings 10, each cell string 10 including multiple cells 11 connected in series, the first cell 11 connected in series in the cell string 10 is a first cell, the last cell 11 connected in series in the cell string 10 is a second cell, the multiple first cells are connected by a first solder ribbon 12, and the multiple second cells are also connected by the first solder ribbon 12, the extension direction of the first solder ribbon 12 is parallel to the extension direction of the first fine grid line in the cell 11.

[0033] In some embodiments, the solar cell includes, but is not limited to, any one of PERC cell, PERT cell (Passivated Emitter and Rear Totally-diffused cell), TOPCon cell (Tunnel Oxide Passivated Contact cell), and HIT / HJT cell (Heterojunction Technology).

[0034] In some embodiments, the solar cell can be a monocrystalline silicon solar cell, a polycrystalline silicon solar cell, an amorphous silicon solar cell, or a multi-component compound solar cell. Specifically, the multi-component compound solar cell can be a cadmium sulfide solar cell, a gallium arsenide solar cell, a copper indium selenide solar cell, or a perovskite solar cell.

[0035] In some embodiments, the solar cell is an interdigitated back contact (IBC) crystalline silicon solar cell. An IBC cell is a back-junction back-contact solar cell structure in which the positive and negative metal electrodes are arranged in an interdigitated manner on the back surface of the cell. Its PN junction and electrodes are located on the back of the cell. That is, the electrodes of the emitter region and the base region of the IBC cell are both on the back, and there are no grid lines blocking the front, which can improve the photoelectric conversion performance of the cell.

[0036] Traditional photovoltaic modules use long, strip-shaped busbars to connect the beginning and end of each cell string. These busbars must span the module's edge, occupying valuable cell placement area and compressing the module's effective power generation area. The above embodiment eliminates the traditional busbar and replaces it with a short, narrow, perpendicular solder strip connecting only the end cells of adjacent strings, achieving electrical series connection between strings. This solder strip is only a few millimeters long and less than 2mm wide, and the welding area is located directly above the cell's main grid, not occupying module edge space. This completely frees up edge space, allowing cells to seamlessly extend to the module frame, achieving a "full-screen" structure and effectively increasing the module's power generation area by 1.5% to 3%.

[0037] Secondly, traditional busbars are rigid metal structures, attached over a large area to the back or edge of the battery. Under thermal cycling and mechanical loads, the difference in thermal expansion coefficients generates huge shear stress, leading to stress concentration at the edges of the battery cells, causing microcracks or even cell breakage. The above embodiment changes the connection point from "long strip edge constraint" to "point local connection." The solder ribbon only acts on the main grid position of the two cells, far away from the vulnerable edge area. Moreover, the solder ribbon itself is narrow, thin, and flexible, and can deform slightly with the silicon wafer, significantly reducing stress transmission and concentration effects. This fundamentally decouples the thermomechanical coupling between strings and greatly alleviates the structural damage caused by rigid connections. Furthermore, the solder ribbon in the above embodiment only connects two cells, with a very small range of action. The welding position is located in the main grid area where the cell strength is highest (rather than the vulnerable edge), and the direction of the solder ribbon is perpendicular to the principal stress direction, without exacerbating the original deformation trend.

[0038] Therefore, in the above embodiment, the first cell of each battery string is designated as the first cell and the last cell as the second cell. All first cells and all second cells are connected by the same first solder strip, with the extension direction of the first solder strip parallel to the extension direction of the first fine grid lines in the cell. This achieves efficient collection and conduction of current between strings. This structure avoids the need for lateral busbars on the outside or back of the cells in traditional technologies, eliminating the obstruction of the effective light-emitting area by the busbars and ensuring sufficient light-receiving area of ​​the cells. Simultaneously, since the solder strip is arranged along the direction of the fine grid lines, consistent with the current transmission path inside the cell, current collection efficiency is improved. Without adding extra structural or process complexity, the effective power generation area of ​​the module can be maximized without sacrificing mechanical strength. Therefore, this solves the problem in existing technologies where the head and tail busbars occupy the effective light-emitting area, limiting the photoelectric conversion efficiency of the module and achieving the effects of improving module power output, optimizing space utilization, and enhancing overall power generation performance.

[0039] The photovoltaic module described in this application comprises multiple cell strings, each containing multiple cells connected in series. The first cell connected in series within a cell string is called a first cell, and the last cell connected in series within a cell string is called a second cell. Multiple first cells are connected by a first solder strip, and multiple second cells are also connected by a first solder strip. The extension direction of the first solder strip is parallel to the extension direction of the first fine grid lines in the cell. The photovoltaic module provided in this application connects two cell strings in series by designing solder strip interconnects perpendicular to the main grid at the beginning and end of the cell strings. This eliminates the need for busbars at the beginning and end of the cell strings, solving the problem in the prior art where the series connection method of photovoltaic module cell strings limits the power generation area of ​​the cells or easily leads to microcracks / breakage risks.

[0040] In some embodiments, both the first and second solar cells have multiple main grid lines of different polarities, and the first solder strip is connected to the main grid line of the first polarity.

[0041] In this configuration, the first polarity can be either positive or negative, and the corresponding second polarity can be either negative or positive. Both the first and second solar cells are cells with main grids. The first and last solar cells must have main grids because the main grid is the only optimized conductive structure on the cell with low resistance and high adhesion. Only by welding it to the main grid can a stable, low-contact-resistance electrical connection be ensured between the vertical solder strips and the solar cell. If welded to a silicon surface without a main grid, it will lead to poor contact, concentrated current density, localized overheating, or even desoldering, causing the entire inter-string series connection to fail and failing to meet the basic requirements for welding reliability, consistency, and safety in the mass production of photovoltaic modules.

[0042] In this embodiment, the first and second solar cells serve as the start and end points of each battery string, respectively. Multiple main grid lines of different polarities are provided on each cell to carry the positive and negative charges generated within the cell and facilitate their exit. The first solder ribbon serves as an inter-string conductive structure connecting multiple first and second solar cells. Its extension direction is parallel to the first fine grid lines in the solar cells to optimize the current collection path and reduce the shading area. Crucially, the first solder ribbon is only electrically connected to a main grid line of one polarity. This first polarity is typically a uniformly defined conductive path between the positive and negative terminals. For example, in a standard series architecture, the first and last cells of all battery strings are connected in series via the positive main grid line, preventing the solder ribbon from being mistakenly connected to the opposite polarity. The main grid lines of the battery cell cause a low-resistance path to be formed between adjacent battery strings. For example, if a battery cell has both a positive and a negative main grid line, the current can only flow from the tail of one string to the head of the next string along a preset path if the first solder strip is firmly soldered to the positive main grid line. If it is mistakenly connected to the negative main grid line, it may cause a short circuit between strings that should be isolated, resulting in power loss or even hot spot effect. By limiting the first solder strip to only connect to the first polarity main grid line, the polarity consistency and electrical isolation of the inter-string connection are ensured. Thus, without using traditional busbars, the effective light-emitting area of ​​the battery cell is preserved, and the risk of inter-string short circuit caused by incorrect polarity connection is completely avoided, significantly improving the safety and power generation efficiency of the module.

[0043] Conventional solar cells include main grid lines and auxiliary grid lines. The auxiliary grid lines intersect the main grid lines in their extension directions. The auxiliary grid lines collect current from the substrate, while the main grid lines collect the current from the auxiliary grid lines and transmit it to the solder ribbon. In some embodiments, the first fine grid line is an auxiliary grid line used to guide current. The solar cells provided in this application do not explicitly show the main grid lines and the first fine grid line, but both the first and second solar cells have a main grid structure. The remaining solar cells can have either a gridless structure or a main grid structure. A gridless structure can shorten the carrier transport path and reduce series resistance, thereby increasing the front-side light-receiving area, improving module power, and helping to increase short-circuit current. This reduces the amount of silver paste used for grid line printing, thus lowering production costs.

[0044] In some embodiments, the main grid line of the first polarity has multiple solder joints, and the first solder strip is connected to the main grid line of the first polarity through the solder joints.

[0045] In this embodiment, multiple solder joints are provided on the main grid line of the first polarity. This means that several discrete metal contact areas for welding and fixing are pre-formed on the conductive lines of the main grid line of the battery cell responsible for conducting current of a specific polarity (such as positive or negative). These solder joints are formed by precise printing or electroplating processes, and their size and distribution density are optimized to ensure that when the first solder strip is laid in a direction parallel to the fine grid line, it can achieve mechanical anchoring and electrical connection through multiple point-like welding areas, rather than relying solely on the overall surface contact between the solder strip and the main grid line. For example, when the first solder strip crosses the beginning and end of multiple series-connected battery cells, if... Relying solely on long strip-shaped press welding can easily lead to desoldering or incomplete connections due to thermal stress or mechanical deformation. However, a multi-solder-point structure can effectively disperse stress, enhance adhesion strength, and reduce the current density per unit solder point, thereby significantly reducing the cumulative effect of contact resistance. Through this structure, a stable, low-resistance, and high-strength multi-point connection system is established between the first solder strip and the first polarity main grid line, fundamentally solving the dual defects of wasted effective component area and insufficient connection reliability caused by the traditional head and tail busbar connection method. This achieves long-term stability and high efficiency of inter-string current transmission without occupying additional photosensitive area.

[0046] In some embodiments, such as Figure 2 As shown, the first solar cell is connected to the adjacent solar cell 11 via a second solder ribbon 13. The second polarity main grid line on the first solar cell is connected to the second solder ribbon 13. The second solder ribbon 13 covers the second polarity main grid line. The photovoltaic module also includes an insulating layer 14, which is located between the first solder ribbon 12 and the second solder ribbon 13.

[0047] in, Figure 2The insulating layer shown is rectangular, but in some embodiments, the shape of the insulating layer can be any shape, not limited to a rectangle, but can also be elliptical or irregularly shaped, as long as it meets the requirements of the second solder strip.

[0048] In this embodiment, the first solar cell serves as the starting end of the cell string and is electrically connected to adjacent solar cells via a second solder strip. This second solder strip directly covers and is welded to the second polarity main grid line on the first solar cell, thus avoiding the problem of traditional busbars occupying effective light-receiving area at the module end. Simultaneously, the direct contact between the solder strip and the main grid line achieves low-resistance conduction. To prevent electrical short circuits between the first solder strip shared by the second solar cell at the end of the adjacent cell string and the first solder strip, an insulating layer is specifically provided between the first and second solder strips. This insulating layer is made of a non-conductive material (such as PET or epoxy resin film), physically isolating the overlapping area of ​​the two sets of solder strips. Even under micro-stress during module encapsulation, thermal compression, or mechanical stress, this prevents short circuits. Displacement also ensures that there is no electrical contact between the first solder strip (connecting multiple second cells and transmitting the first polarity current) and the second solder strip (connecting the first cell and transmitting the second polarity current). For example, in the module head region, if the first solder strip extends laterally along the grid direction to connect the tail cells of multiple strings, while the second solder strip connects longitudinally to the main grid line of the first cell, the two are arranged in parallel or intersecting space, which can easily lead to short circuits due to insulation failure. The intervention of the insulation layer completely blocks this risk path. Through the above structural synergy, efficient series connection between cell strings without busbars is achieved, and the electrical safety of polarity separation in the module head and tail regions is ensured, significantly improving the module's photoelectric conversion efficiency and long-term operational reliability.

[0049] In some embodiments, such as Figure 1 As shown, the insulating layer includes a plurality of intermittently arranged insulating strips 141, one of the insulating strips 141 covering one of the second solder strips 13, the length of the insulating strip 141 in a first direction being greater than or equal to the length of the second solder strip 13 in the first direction, the first direction being the arrangement direction of the battery string 10.

[0050] The length of the insulating strip in the first direction is actually the width of the insulating strip, and the length of the second welding strip in the first direction is actually the width of the second welding strip. Figure 1 The insulating strip shown is rectangular, but in some embodiments, the shape of the insulating strip can be any shape, not limited to a rectangle, but can also be an ellipse or an irregularly shaped pattern, as long as it meets the requirements of the second solder strip.

[0051] In this embodiment, the first solder strip is used to connect multiple second solar cells in series. Its extension direction is parallel to the first fine grid line on the solar cell to ensure efficient current conduction along the main grid direction of the solar cell, while avoiding the introduction of additional resistance or stress concentration due to the intersection of the solder strip and the fine grid line. To prevent the first solder strip from causing a short circuit when it comes into physical contact with the non-polar solder strip of an adjacent solar cell string, an insulating layer consisting of multiple intermittent insulating strips is laid on its surface. Each insulating strip precisely corresponds to and covers one second solder strip, and the width of the insulating strip is not less than the width of the second solder strip, ensuring that even under thermal expansion or mechanical displacement... The insulating strip can still completely shield the potential contact area between the second solder strip and the adjacent non-polar solder strip. For example, when the width of the second solder strip is 5mm, the width of the corresponding insulating strip should be at least 5mm, or even extended to 6mm to provide a safety margin. This intermittent insulating strip design not only ensures full coverage of critical short-circuit risk points, but also avoids material waste and increased process complexity caused by continuous insulation layers. Thus, without increasing the thickness of the module or the light-shielding area, it achieves precise and reliable protection of inter-string electrical isolation, significantly improving the safety and reliability of the module in high humidity, high temperature or long-term operating environments.

[0052] In some embodiments, the length of the insulating strip in the first direction is positively correlated with the spacing between two adjacent main grid lines.

[0053] In this embodiment, the length of the insulating strip in the first direction is actually the width of the insulating strip. The length of the insulating strip in the first direction is positively correlated with the spacing between two adjacent main grid lines. This means that when the main grid lines on the cell are sparser, the insulating strip is widened accordingly to ensure that it completely covers the second solder strip located below it. Conversely, when the spacing between the main grid lines is narrower, the length of the insulating strip is also narrowed to avoid material redundancy. Furthermore, this positive correlation ensures that even under thermal expansion or mechanical displacement, the insulating strip can still completely shield the potential contact area between the second solder strip and the adjacent non-polar solder strip. This design, by precisely matching the size of the insulating strip with the spacing between the main grid lines, completely eliminates the risk of short circuits caused by solder strip exposure due to a fixed-length insulating strip, while avoiding film waste and process redundancy caused by over-coverage, achieving dual optimization of electrical safety and material efficiency.

[0054] In some embodiments, the length of the insulating strip in the first direction is 10mm ± 5mm.

[0055] In this embodiment, the length of the insulating strip in the first direction is actually the width of the insulating strip. The length of the insulating strip in the first direction is limited to 10mm ± 5mm, that is, its actual length range is 5mm to 15mm. This setting ensures that each insulating strip can completely cover its corresponding second solder strip, avoiding the risk of short circuit between adjacent electrodes caused by exposed solder strip edges due to insufficient length. At the same time, it prevents redundant accumulation of insulating material in the edge area of ​​the module due to a length exceeding 15mm, thereby effectively saving encapsulation material and improving the utilization rate of the effective light-emitting area of ​​the module. For example, when the width of the second solder strip is 8mm, the length of 10mm ± 5mm ensures that even with installation tolerances, the insulating strip can still completely cover both ends and sides of the solder strip, instead of only covering half of the solder strip as with a 3mm insulating strip, or encroaching on the wiring space of adjacent cell strings as with a 20mm insulating strip. By precisely controlling the length of the insulating strip within this range, an optimal balance between electrical safety and space efficiency is achieved. This ensures the long-term insulation reliability of the module in harsh environments such as high humidity and high temperature, while minimizing the ineffective occupation of non-power generation areas, thereby improving the overall photoelectric conversion efficiency and manufacturing economy.

[0056] In some embodiments, the length of the first solder strip in the first direction is 0.6 mm to 2.0 mm, and the length of the first solder strip in the second direction is 0.05 mm to 0.20 mm. The first direction is the arrangement direction of the battery string, and the second direction is the direction perpendicular to the first surface of the battery string. The first surface is the surface with the largest area of ​​the battery string.

[0057] Wherein, the length of the first solder strip in the first direction is actually the width of the first solder strip, and the length of the first solder strip in the second direction is actually the thickness of the solder strip.

[0058] In this embodiment, the width of the first solder strip is limited to 0.6mm to 2.0mm. This length range ensures that the solder strip only overlaps a small area at the ends of adjacent cells, providing sufficient electrical connection area to ensure low-resistance conduction while preventing the solder strip from extending too far into the effective light-receiving area of ​​the cell. For example, if the solder strip length exceeds 2.0mm, it may cover part of the light-receiving area outside the main busbar of the cell, resulting in a loss of effective power generation area. Simultaneously, the thickness of the solder strip is limited to 0.05mm to 0.20mm. This thickness range makes the solder strip ultra-thin and flat, significantly reducing the local protrusions formed after module lamination and preventing excessive solder strip thickness (e.g., >0.20mm) from causing... This design addresses issues such as uneven local compression of EVA encapsulation materials, the generation of bubbles or interlayer debonding, and stress concentration on subsequent glass or backsheets, preventing the risk of microcracks. The first solder strip extends parallel to the first fine grid line of the solar cell, creating a current conduction path in the same direction between the solder strip and the fine grid line. This reduces contact resistance and evenly distributes current density, avoiding local overheating and poor soldering caused by perpendicular intersections. By comprehensively controlling the dimensions and orientation, the solder strip achieves reliable inter-string connections while maximizing the effective light-receiving area of ​​the solar cell, reducing the risk of encapsulation defects, and improving the long-term reliability of the module. This fundamentally solves the problems of shading, stacking, and failure caused by traditional busbars or thick solder strips.

[0059] In some embodiments, the nth solar cell and the (n+1)th solar cell are connected in series via a third solder strip, and the (n+1)th solar cell and the (n+2)th solar cell are connected in series via a fourth solder strip. The third solder strip is connected to the first fine grid line, and the fourth solder strip is connected to the second fine grid line of the solar cell. The first fine grid line and the second fine grid line have different polarities.

[0060] When n is 1, the third solder strip is... Figure 1 and Figure 2 The second solder strip 13 in the middle means that every two adjacent cells are connected by a solder strip.

[0061] In this embodiment, the nth and (n+1)th solar cells are connected in series via a third solder ribbon. This means that adjacent solar cells no longer rely on traditional busbars for intra-string connection, but are directly connected via solder ribbons to the output end of the previous solar cell and the input end of the next solar cell, thus avoiding occupying the effective light-emitting area at the edge of the module. The (n+1)th and (n+2)th solar cells are connected in series via a fourth solder ribbon, further realizing a continuous and alternating series structure, ensuring that the current is stably transmitted cell by cell within the string. The third solder ribbon is connected to the first fine grid line, and the fourth solder ribbon is connected to the second fine grid line. This means that the solder ribbons are not randomly soldered to any grid line, but are precisely matched to the fine grid lines with different electrode polarities on the solar cell—the first fine grid line is usually a front-side P-type grid line used to collect holes, and the second fine grid line is a back-side N-type grid line used to collect electrons. The two polarities are opposite, and they are connected to the corresponding polarity grid lines via solder ribbons to form a low-impedance current path, avoiding short circuits or a sharp increase in contact resistance due to incorrect positive and negative connections. For example, when the front grid line of the (n+1)th cell is used as the output terminal, it is connected to the back output terminal of the nth cell via the third solder ribbon, while the back grid line of the (n+1)th cell is connected to the front input terminal of the (n+2)th cell via the fourth solder ribbon, forming an alternating series path of "positive-negative-positive-negative" polarities, ensuring that electrons and holes can be transferred smoothly at each series node. This structural design completely eliminates the risk of connection failure caused by the mismatch of fine grid line polarities, while avoiding the problem of traditional head and tail busbars occupying the effective area of ​​the module, achieving synergistic optimization of high reliability of the internal series structure of the cell string and maximization of the overall photoelectric conversion area of ​​the module.

[0062] In some embodiments, the solar cells have multiple main grid lines of different polarities.

[0063] In this embodiment, each solar cell has multiple main grid lines of different polarities, meaning that each cell has at least two conductive main grid lines that respectively lead out P-type and N-type charges, rather than a traditional unipolar main grid structure. This allows the solder ribbon to flexibly choose to solder to the positive or negative main grid line according to the series path requirements when connecting adjacent cells, thereby achieving polarity continuity across the beginning and end of the cell string without using traditional busbars. Specifically, when multiple first solar cells (the beginning of each string) are connected in parallel through the first solder ribbon, the solder ribbon can be simultaneously soldered to the negative main grid line of each first solar cell, while multiple second solar cells (the end of each string) are soldered to the negative or positive main grid line through the same first solder ribbon, depending on the series direction. The design establishes a chain-like current path with either "positive-negative-positive" or "negative-positive-negative". For example, the positive main grid line at the end of the first string can be directly connected to the negative main grid line at the beginning of the second string through the first solder strip, completing the inter-string series connection and completely bypassing the physical space occupied by the traditional busbar. The design of the first solder strip extending parallel to the first fine grid line ensures that the solder strip layout is compatible with the electric field distribution on the surface of the cell, reducing shading loss. The presence of the multi-polar main grid line gives the parallel solder strip the ability to switch polarities, breaking through the technical bottleneck that multi-polar cross-string conduction cannot be achieved by welding only in the direction of the fine grid line. Overall, it achieves the complete replacement of the busbar with structural innovation without increasing the module area loss, significantly improving the effective light-emitting area and power density of the module.

[0064] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A photovoltaic module, characterized in that, include: Multiple battery strings, each battery string comprising multiple battery cells connected in series, wherein the first battery cell connected in series in the battery string is a first battery cell, and the last battery cell connected in series in the battery string is a second battery cell, the multiple first battery cells are connected by a first solder strip, and the multiple second battery cells are also connected by the first solder strip, wherein the extension direction of the first solder strip is parallel to the extension direction of the first fine grid line in the battery cell.

2. The photovoltaic module according to claim 1, characterized in that, Both the first and second solar cells have multiple main grid lines of different polarities, and the first solder strip is connected to the main grid line of the first polarity.

3. The photovoltaic module according to claim 2, characterized in that, The main grid line of the first polarity has multiple solder joints, and the first solder strip is connected to the main grid line of the first polarity through the solder joints.

4. The photovoltaic module according to claim 2, characterized in that, The first solar cell is connected to the adjacent solar cell via a second solder strip. The second polarity main grid line on the first solar cell is connected to the second solder strip, and the second solder strip covers the second polarity main grid line. The photovoltaic module further includes: An insulating layer is located between the first solder strip and the second solder strip.

5. The photovoltaic module according to claim 4, characterized in that, The insulating layer includes a plurality of intermittently arranged insulating strips, one of which covers one of the second solder strips. The length of the insulating strip in a first direction is greater than or equal to the length of the second solder strip in the first direction, which is the arrangement direction of the battery string.

6. The photovoltaic module according to claim 5, characterized in that, The length of the insulating strip in the first direction is positively correlated with the spacing between two adjacent main grid lines.

7. The photovoltaic module according to claim 5, characterized in that, The length of the insulating strip in the first direction is 10mm ± 5mm.

8. The photovoltaic module according to any one of claims 1 to 5, characterized in that, The length of the first solder strip in the first direction is 0.6mm to 2.0mm, and the length of the first solder strip in the second direction is 0.05mm to 0.20mm. The first direction is the arrangement direction of the battery string, and the second direction is the direction perpendicular to the first surface of the battery string. The first surface is the surface with the largest area of ​​the battery string.

9. The photovoltaic module according to claim 1, characterized in that, The nth solar cell is connected in series with the (n+1)th solar cell via a third solder strip, and the (n+1)th solar cell is connected in series with the (n+2)th solar cell via a fourth solder strip. The third solder strip is connected to the first fine grid line, and the fourth solder strip is connected to the second fine grid line of the solar cell. The first fine grid line and the second fine grid line have different polarities, and n is a positive integer.

10. The photovoltaic module according to claim 1, characterized in that, Each of the solar cells has multiple main grid lines of different polarities.

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