Photovoltaic cell unit and applications thereof

Abstract

The application provides a photovoltaic cell unit, which comprises conductive connecting strips arranged on both sides of a cell piece and parallel to each other, and the front and back surfaces of the cell piece are connected to one conductive connecting strip through a plurality of metal wires. The application also provides two preparation methods of photovoltaic assemblies. The application can reduce the silver consumption of the surface of the cell piece and the light shielding of the metal wires, and improve the manufacturing speed of the photovoltaic assembly. In the cell piece placing process, the application can place a plurality of cell pieces at the same time, and improve the placing speed. The application can weaken the cell piece placing precision, and the placing process no longer needs visual and robot high-precision positioning, and the effective placing of the cell piece can be realized through simple mechanical positioning. The scheme of the application is suitable for the interdigitated cell with an interdigitated structure, the photo-generated current of the interdigitated cell vertically flows through the ultrathin seed layer from the inside of the cell piece to the metal wire, there is no horizontal transmission process, the resistance loss is small, the consumption of precious metal silver can be saved, and the light shielding of the silver grid line can be avoided.

Description

Technical Field

[0001] This invention relates to a photovoltaic cell unit and its application. Background Technology

[0002] In the existing crystalline silicon photovoltaic industry chain, silicon wafers are used to make solar cells. Metal patterns for collecting current are pre-prepared on the surface of the cells; these patterns are called fine grids. Considering both shading and current transmission losses, the aspect ratio of the fine grids should be as large as possible. The patterns used for connecting the cells in series and collecting the current from the fine grids are called main grids. To a certain extent, the more main grids there are, the less silver loss and the narrower the fine grids can be, and the lower the thermal resistance loss, resulting in lower silver loss and higher efficiency. Therefore, the number of main grids in solar cells has been continuously increasing. At the module level, the more main grids there are, the more numerous and finer the solder ribbons required to connect the cells, increasing the difficulty of module manufacturing and process control. Currently, multi-busbar cells in the market mainly use round wire solder ribbons or triangular solder ribbons. While serving as a connection circuit, their surface light reflection can be reused to improve the light utilization rate of the module. The number of main busbars in multi-busbar cells is mainly 9 to 20. Compared with the number of fine grids and the width of the cell, the number of main busbars and the actual light-shielding area of ​​the solder ribbon are still relatively small, and the impact on the light utilization rate of the entire module is still relatively limited. Therefore, there are not many strict and specific requirements for the solder ribbon itself, such as the chamfering of the triangular solder ribbon and the reflectivity requirements of the solder ribbon surface.

[0003] Existing photovoltaic modules have the following drawbacks: The current path of the solar cell is complex. The photogenerated current is collected from the cell substrate to the fine grid lines, then transmitted laterally to the main grid lines, then longitudinally to the solder ribbon, and finally transmitted out of the cell through the solder ribbon. Excessive silver consumption in metallized solar cells; The large area of ​​light-shielding metal on the surface of the solar cell affects the efficiency of the cell and module. The current in the solar cell is transmitted and collected through the fine grid metal on the surface. The thermal resistance loss during the transmission process reduces the output power of the cell and the module. Photovoltaic modules are slow to manufacture. The cells in the module are connected in series by a solder strip to the front and back of adjacent cells. This connection method makes it difficult to increase the module manufacturing speed significantly after it reaches a certain level. In conventional modules, the light utilization rate in the gaps between solar cells is low. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention provides a photovoltaic cell unit, including a cell and a first conductive connecting strip and a second conductive connecting strip disposed on both sides of the cell; the first conductive connecting strip and the second conductive connecting strip are parallel to each other; The front side of the battery cell is connected to the bottom surface of the first conductive connecting strip by a plurality of parallel first metal wires; each first metal wire is fixed to the bottom surface of the first conductive connecting strip by an electrical connecting material; each first metal wire is also fixed to the front side of the battery cell by an electrical connecting material; and the end of each first metal wire away from the first conductive connecting strip does not extend to the outside of the battery cell. The back of the battery cell is connected to the top surface of the second conductive connecting strip by a plurality of parallel second metal wires; each second metal wire is fixed to the top surface of the second conductive connecting strip by an electrical connecting material; each second metal wire is also fixed to the back of the battery cell by an electrical connecting material; and the end of each second metal wire away from the second conductive connecting strip does not extend to the outside of the battery cell.

[0005] Preferably, the electrical connection materials on the bottom surface of the first conductive connecting strip and the top surface of the second conductive connecting strip can be remelted and solidified during the component lamination process.

[0006] For details of the photovoltaic cell unit of the present invention, please refer to Example 1.

[0007] The present invention also provides two methods for preparing photovoltaic modules, both of which use the above-mentioned photovoltaic cell units. For specific steps, please refer to Examples 2 and 3.

[0008] The advantages and beneficial effects of this invention are as follows: The photovoltaic cell unit of the present invention incorporates metal wires (first metal wire, second metal wire) and conductive connecting strips (first conductive connecting strip, second conductive connecting strip) on the cell, and can be regarded as a whole, which is a cell unit. The entire process from the cell unit to the photovoltaic module is the photovoltaic module manufacturing process. Because all the metal wires (first metal wire, second metal wire) for collecting and transmitting current and the conductive connecting strips (first conductive connecting strip, second conductive connecting strip) for connecting the cells are pre-connected on the cell, the module process is much simpler than the traditional module process.

[0009] In the photovoltaic cell unit structure of this invention, the current on the surface of the cell (front and back) can be directly collected and transmitted through metal wires (first and second metal wires). The number and density of metal wires on the cell surface can be extremely high; for example, a 166mm wide cell can have more than 120 metal wires. Traditional module stringing and encapsulation processes are no longer sufficient to encapsulate this structure. The biggest difference between the module fabrication method of this invention and traditional methods is that it eliminates the need for traditional stringing steps. Traditional stringing processes no longer meet the requirements for connecting cells with such a large number of metal wires. This invention first combines metal wires (first and second metal wires) and conductive connecting strips (first and second conductive connecting strips) onto the cell to form independent photovoltaic cell units, and then connects these units end-to-end. This simplifies the connection process while achieving series connection of cells with a large number of metal wires. Furthermore, this invention allows for the simultaneous placement of multiple battery cells during the cell placement process, thereby increasing the placement speed. In addition, this invention can reduce the precision required for cell arrangement, eliminating the need for high-precision positioning via vision and robots in the placement process. Effective placement of battery cells can be achieved through simple mechanical positioning.

[0010] This invention provides an effective method for splicing numerous ultra-fine metal wires. The electrical connection between battery cells is achieved by sandwiching metal wires (first metal wire and second metal wire) in the middle with conductive connecting strips (first conductive connecting strip and second conductive connecting strip), and then welding them at high temperature using a laminator. This simple and effective method can achieve splicing between fine metal wires and ensure the effective transmission of current between battery cells on each metal wire.

[0011] For batteries with a transparent conductive layer (TCO) on the surface (such as HJT batteries), the metal wires (first metal wire, second metal wire) can be directly electrically connected to the TCO via conductive adhesive or alloys. For batteries without a TCO on the surface, the metal wires (first metal wire, second metal wire) can be electrically connected to the metal grid lines on the battery surface via conductive adhesive or alloys. This structure can be applied to most solar cells, including PERC, TOPCon, and HJT, which have surface metal patterns and those without, that collect current through a TCO.

[0012] In this invention, the photocurrent generated by the photovoltaic cell unit is collected on the surface of the cell (front and back) and transmitted to the metal wires (first metal wire and second metal wire). It can bypass the grid and the metal wires (first metal wire and second metal wire) have much lower resistance than the grid. Therefore, the thermal resistance loss of the current transmission in the metal wires (first metal wire and second metal wire) can be greatly reduced. With the loss reduced, the output power of the module is higher.

[0013] This invention reduces the amount of silver paste consumed in battery modules. Current on the surface of the battery cells (front and back) is collected and transmitted through metal wires (first and second metal wires). The silver paste only serves to connect the metal wires and the battery cells. Current only needs to be transmitted vertically across the battery cell surface, not laterally, thus eliminating the need for extensive silver paste stacking and reducing lateral transmission resistance. The silver paste height can be reduced to below 5μm, significantly lowering silver paste consumption. This can be applied to PERC, TOPCon, HJT, and other battery types, resulting in a substantial reduction in silver consumption, up to 80% or more.

[0014] Traditional battery grids and solder ribbons result in 3% to 5% light shading, leading to significant light loss. In this invention, the metal lines (first metal line and second metal line) on the surface of the battery cell have a preferred high-reflectivity triangular cross-sectional shape. Direct light is reflected off the metal line surface and ultimately reaches the battery cell, where it is absorbed. Therefore, the metal lines do not block incident light from the battery cell surface, resulting in high light reception and consequently high efficiency for the battery module.

[0015] The inter-cell conductive connecting strip (first conductive connecting strip and second conductive connecting strip) of the present invention can have a high-reflection sawtooth structure, which forms a secondary total internal reflection of the incident light and ultimately returns it to the solar cell, thereby improving the utilization of the light between the solar cells. At present, there is no simple, effective and easy-to-operate method for utilizing the incident light between the solar cells. The inter-cell conductive connecting strip (first conductive connecting strip and second conductive connecting strip) designed in this invention can achieve simple operation and effective utilization.

[0016] As can be seen from the above, the present invention can significantly reduce the silver consumption on the surface of the solar cell and the light shading of the metal lines, and significantly improve the manufacturing speed of photovoltaic modules.

[0017] The solution of this invention is applicable to stacked grid cells with a stacked grid structure, such as... Figure 4 As shown, the stacked grid structure includes: a grid-like ultrathin seed layer disposed on the surface of the solar cell, and metal lines stacked on the ultrathin seed layer; the metal lines are parallel to the ultrathin seed layer in which they reside, and the width of the metal lines is not less than the width of the ultrathin seed layer in which they reside; the thickness of the ultrathin seed layer is ≤5μm; specifically, as shown... Figure 5 As shown, the metal wire is fixed to the ultrathin seed layer it is in by a conductive connecting material; more specifically, the metal wire is fixed to the ultrathin seed layer by welding, conductive curing adhesive or conductive tape.

[0018] The ultrathin seed layer is mainly used to collect and longitudinally export the photocurrent in the cell matrix, while the metal wire is mainly used to transmit the photocurrent out of the cell. Specifically, the photocurrent transmission path of the stacked grid cell is as follows: the current is collected from the cell substrate to the grid-like ultrathin seed layer, then transmitted longitudinally from the grid-like ultrathin seed layer to the metal wire, and then transmitted out of the cell through the metal wire. It does not require lateral current transmission through the grid-like ultrathin seed layer. As can be seen, the structure of the stacked grid cell is simple and the current transmission path is short. The cell substrate, ultrathin seed layer and metal wire are stacked together in the vertical direction. The photocurrent flows vertically from the inside of the cell through the ultrathin seed layer and directly to the metal wire without the lateral transmission process. The resistance loss is small, which can save the amount of precious metal silver consumed in the lateral transmission and avoid or reduce the shading of light by the silver grid lines. Attached Figure Description

[0019] Figure 1 This is a top view schematic diagram of the photovoltaic cell unit of the present invention; Figure 2 This is a side view schematic diagram of the photovoltaic cell unit of the present invention; Figure 3 These are schematic diagrams of the stacking of photovoltaic modules in Embodiments 2 and 3 of the present invention; Figure 4 and Figure 5 This is a schematic diagram of a stacked grid structure. Detailed Implementation

[0020] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0021] The specific technical solution of this invention is as follows: Example 1

[0022] like Figure 1 and Figure 2 As shown, the present invention provides a photovoltaic cell unit, including a rectangular cell and a first conductive connecting strip and a second conductive connecting strip disposed on both sides of the cell; the first conductive connecting strip and the second conductive connecting strip are parallel to a pair of side lines of the cell, and the first conductive connecting strip and the second conductive connecting strip are symmetrically arranged; the distance between the first conductive connecting strip, the second conductive connecting strip and the cell is no greater than 5mm (preferably 0.5-5mm). The front side of the battery cell is connected to the bottom surface of the first conductive connecting strip by a plurality of parallel and spaced first metal wires; each first metal wire is perpendicular to the first conductive connecting strip; the line width of each first metal wire is 0.05 to 0.2 mm; the spacing between two adjacent first metal wires is 1 to 3 mm; each first metal wire is fixed to the bottom surface of the first conductive connecting strip by an electrical connecting material; each first metal wire is also fixed to the front side of the battery cell by an electrical connecting material; and the end of each first metal wire away from the first conductive connecting strip does not extend to the outside of the battery cell. The back of the battery cell is connected to the top surface of the second conductive connecting strip by a plurality of parallel and spaced second metal wires; each second metal wire is perpendicular to the second conductive connecting strip; the line width of each second metal wire is 0.05 to 0.2 mm; the spacing between two adjacent second metal wires is 1 to 3 mm; each second metal wire is fixed to the top surface of the second conductive connecting strip by an electrical connecting material; each second metal wire is also fixed to the back of the battery cell by an electrical connecting material; and the end of each second metal wire away from the second conductive connecting strip does not extend to the outside of the battery cell.

[0023] Specifically: The electrical connection material can be a conductive adhesive (such as a colloidal material filled with conductive particles), a conductive paste (such as silver paste), a solder (such as solder or other alloy materials), or other conductive adhesive materials.

[0024] The cross-sectional shapes of the first and second metal wires can be triangular, circular, semi-circular, trapezoidal, rectangular, etc. Preferably, the cross-sectional shape of the first and second metal wires is triangular, and the chamfer R of the vertex angle of the triangle is ≤0.03mm, the base angles of the triangle are all >45°, and the width of the base side of the triangle is 0.05~0.2mm.

[0025] The surfaces of the first metal wire and the second metal wire can be high reflective surfaces with a reflectivity of ≥80%.

[0026] The cross-sectional shapes of the first and second conductive connecting strips can be triangular, circular, semi-circular, trapezoidal, rectangular, serrated, etc. Preferably, the surface of the first conductive connecting strip connected to the multiple first metal wires has a reflective structure with a reflectivity ≥80%; the surface of the second conductive connecting strip connected to the multiple second metal wires has a reflective structure with a reflectivity ≥80%; the reflective structure can be a triangular serrated structure, and the apex angle of the serrations is 90-140 degrees, and the chamfer R of the apex angle is ≤0.05mm. Example 2

[0027] The difference from Example 1 is as follows: The front side of the battery cell is an insulating surface, and an ultra-thin seed layer is provided on the front side of the battery cell to conduct current. The first metal wire is fixed to the seed layer through an electrical connection material. The thickness of the seed layer is preferably ≤5μm. The seed layer can also be the seed layer in the metallization electroplating process. Example 3

[0028] The difference from Example 1 is as follows: The solar cell has a stacked grid structure; the stacked grid structure includes: a grid-shaped ultrathin seed layer disposed on the surface of the solar cell, and metal wires stacked on the ultrathin seed layer; the metal wires are parallel to the ultrathin seed layer in which they are disposed, and the width of the metal wires is not less than the width of the ultrathin seed layer in which they are disposed; the thickness of the ultrathin seed layer is ≤5μm; the metal wires are fixed to the ultrathin seed layer in which they are disposed by a conductive connecting material; specifically, the metal wires are fixed to the ultrathin seed layer in which they are disposed by welding, conductive curing adhesive, or conductive tape, etc. More specifically: The ultrathin seed layer includes: a plurality of first ultrathin seed layers disposed on the front side of the battery cell and corresponding one-to-one with the first metal line, and a plurality of second ultrathin seed layers disposed on the back side of the battery cell and corresponding one-to-one with the second metal line; The first metal wire is stacked on the corresponding first ultrathin seed layer; the first metal wire is parallel to the first ultrathin seed layer in which it is located, and the width of the first metal wire is not less than the width of the first ultrathin seed layer in which it is located; the thickness of the first ultrathin seed layer is ≤5μm; the first metal wire and the first ultrathin seed layer in which it is located are fixed together by a conductive connecting material; specifically, the first metal wire and the first ultrathin seed layer in which it is located are fixed together by welding, conductive curing adhesive or conductive tape, etc. The second metal wire is stacked on the corresponding second ultrathin seed layer; the second metal wire is parallel to the second ultrathin seed layer in which it is located, and the width of the second metal wire is not less than the width of the second ultrathin seed layer in which it is located; the thickness of the second ultrathin seed layer is ≤5μm; the second metal wire and the second ultrathin seed layer in which it is located are fixed together by a conductive connecting material; specifically, the second metal wire and the second ultrathin seed layer in which it is located are fixed together by welding, conductive curing adhesive or conductive tape. Example 4

[0029] like Figure 3 As shown, the present invention also provides a method for preparing a photovoltaic module, which uses the photovoltaic cell unit of Example 1, Example 2 or Example 3, and the electrical connection material of the bottom surface of the first conductive connecting strip and the top surface of the second conductive connecting strip can be remelted and solidified during the module lamination process; the method includes the following steps: 1) Lay out the photovoltaic panel (such as photovoltaic glass) and the front film. The front film is basically the same size as the photovoltaic panel and is laid flat on the photovoltaic panel. 2) Photovoltaic cell units are grasped using a robotic arm or mechanical suction cup (photovoltaic cell units can be grasped individually or in multiples simultaneously), and laid flat on the front film according to the module circuit connection structure to form a cell string; within a single cell string, the first conductive connecting strip of the photovoltaic cell unit is stacked on the second conductive connecting strip of the adjacent photovoltaic cell unit; at this time, the first metal wire on the bottom surface of the first conductive connecting strip and the second metal wire on the top surface of the second conductive connecting strip are sandwiched between the first and second conductive connecting strips, which can ensure the effectiveness of the connection between adjacent cells in the cell string; since the electrical connection on the surface of the cell has been completed (each first metal wire is fixed to the front of the cell; each second metal wire is fixed to the back of the cell), this step only needs to realize the electrical connection between the photovoltaic cell units, so the precision requirement for grasping and placing the cells is much lower, thus multiple cells can be grasped simultaneously, improving the cell placement speed; the stacked first and second conductive connecting strips form conductive connecting strip pairs; 3) Weld busbars and electrode leads; use busbars to connect the batteries in series to complete the entire circuit of the assembly; and weld leads at the outlet positions for connection to external junction boxes; 4) Lay the back film and photovoltaic backsheet (which can be backsheet glass); at this point, the laminate to be laminated is formed; 5) Place the laminated components into a laminator for lamination, so that the laminated components are extruded and bonded into a whole; the lamination temperature is 130-160℃, and during the lamination process, the electrical connection material between the conductive connecting strip pairs melts, and the conductive connecting strip pairs and the first metal wire and the second metal wire between the conductive connecting strip pairs are fixed together to achieve a stable electrical connection between adjacent battery cells. 6) Install the junction box and component frame and cure. Example 5

[0030] like Figure 3 As shown, the present invention also provides another method for preparing a photovoltaic module, which uses the photovoltaic cell unit of Example 1, Example 2 or Example 3, and includes the following steps: 1) Lay out the photovoltaic panel (such as photovoltaic glass) and the front film. The front film is basically the same size as the photovoltaic panel and is laid flat on the photovoltaic panel. 2) Photovoltaic cell units are grasped using a robotic arm or mechanical suction cup (photovoltaic cell units can be grasped individually or in multiples simultaneously), and laid flat on the front film according to the module circuit connection structure to form a cell string; within a single cell string, the first conductive connecting strip of the photovoltaic cell unit is stacked on the second conductive connecting strip of the adjacent photovoltaic cell unit; at this time, the first metal wire on the bottom surface of the first conductive connecting strip and the second metal wire on the top surface of the second conductive connecting strip are sandwiched between the first and second conductive connecting strips, which can ensure the effectiveness of the connection between adjacent cells in the cell string; since the electrical connection on the surface of the cell has been completed (each first metal wire is fixed to the front of the cell; each second metal wire is fixed to the back of the cell), this step only needs to realize the electrical connection between the photovoltaic cell units, so the precision requirement for grasping and placing the cells is much lower, thus multiple cells can be grasped simultaneously, improving the cell placement speed; the stacked first and second conductive connecting strips form conductive connecting strip pairs; 3) Heating the electrical connection material between the conductive connecting strip pairs melts and then solidifies the electrical connection material between the conductive connecting strip pairs, thus fixing the conductive connecting strip pairs and the first and second metal wires between them together to achieve a stable electrical connection between adjacent battery cells. 4) Weld busbars and electrode leads; use busbars to connect the batteries in series to complete the entire circuit of the assembly; and weld leads at the outlet positions for connection to external junction boxes; 5) Lay the back film and photovoltaic backsheet (which can be backsheet glass); at this point, the laminate to be laminated is formed; 6) Place the laminated parts into a laminator for lamination, so that the laminated parts are compressed and bonded into a whole; 7) Install the junction box and component frame and cure.

[0031] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A photovoltaic cell unit, characterized in that, It includes a battery cell, and a first conductive connecting strip and a second conductive connecting strip disposed on both sides of the battery cell; the first conductive connecting strip and the second conductive connecting strip are parallel to each other; The front side of the battery cell is connected to the bottom surface of the first conductive connecting strip by a plurality of parallel first metal wires; each first metal wire is fixed to the bottom surface of the first conductive connecting strip by an electrical connecting material; each first metal wire is also fixed to the front side of the battery cell by an electrical connecting material; and the end of each first metal wire away from the first conductive connecting strip does not extend to the outside of the battery cell. The back of the battery cell is connected to the top surface of the second conductive connecting strip by a plurality of parallel second metal wires; each second metal wire is fixed to the top surface of the second conductive connecting strip by an electrical connecting material; each second metal wire is also fixed to the back of the battery cell by an electrical connecting material; and the end of each second metal wire away from the second conductive connecting strip does not extend to the outside of the battery cell. The front side of the battery cell is an insulating surface, and a seed layer for conducting current is provided on the front side of the battery cell. The first metal wire is fixed to the seed layer through an electrical connection material. The surfaces of the first and second metal wires are highly reflective surfaces with a reflectivity ≥ 80%. The surface of the first conductive connecting strip connected to multiple first metal wires is provided with a reflective structure with a reflectivity ≥ 80%; the surface of the second conductive connecting strip connected to multiple second metal wires is provided with a reflective structure with a reflectivity ≥ 80%.

2. A photovoltaic cell unit, characterized in that, It includes a battery cell, and a first conductive connecting strip and a second conductive connecting strip disposed on both sides of the battery cell; the first conductive connecting strip and the second conductive connecting strip are parallel to each other; The front side of the battery cell is connected to the bottom surface of the first conductive connecting strip by a plurality of parallel first metal wires; each first metal wire is fixed to the bottom surface of the first conductive connecting strip by an electrical connecting material; each first metal wire is also fixed to the front side of the battery cell by an electrical connecting material; and the end of each first metal wire away from the first conductive connecting strip does not extend to the outside of the battery cell. The back of the battery cell is connected to the top surface of the second conductive connecting strip by a plurality of parallel second metal wires; each second metal wire is fixed to the top surface of the second conductive connecting strip by an electrical connecting material; each second metal wire is also fixed to the back of the battery cell by an electrical connecting material; and the end of each second metal wire away from the second conductive connecting strip does not extend to the outside of the battery cell. The battery cell has a stacked grid structure; the stacked grid structure includes a grid-shaped ultrathin seed layer disposed on the surface of the battery cell, and metal wires stacked on the ultrathin seed layer; the metal wires are parallel to the ultrathin seed layer in which they are located, and the width of the metal wires is not less than the width of the ultrathin seed layer in which they are located. The metal wires include: a first metal wire and a second metal wire; the ultrathin seed layer includes: a plurality of first ultrathin seed layers disposed on the front side of the battery cell and corresponding one-to-one with the first metal wires, and a plurality of second ultrathin seed layers disposed on the back side of the battery cell and corresponding one-to-one with the second metal wires. The surfaces of the first and second metal wires are highly reflective surfaces with a reflectivity ≥ 80%. The surface of the first conductive connecting strip connected to multiple first metal wires is provided with a reflective structure with a reflectivity ≥ 80%; the surface of the second conductive connecting strip connected to multiple second metal wires is provided with a reflective structure with a reflectivity ≥ 80%.

3. The photovoltaic cell unit according to claim 1 or 2, characterized in that, The electrical connection material is a conductive adhesive, conductive paste, or solder.

4. The photovoltaic cell unit according to claim 1 or 2, characterized in that, The battery cell is rectangular; the first and second conductive connecting strips are parallel to a pair of side lines of the battery cell; each first metal wire and each second metal wire are parallel to the other pair of side lines of the battery cell.

5. The photovoltaic cell unit according to claim 1 or 2, characterized in that, The first conductive connecting strip and the second conductive connecting strip are arranged symmetrically.

6. The photovoltaic cell unit according to claim 1 or 2, characterized in that, The plurality of first metal wires are arranged at equal intervals, with the spacing between two adjacent first metal wires being 1 to 3 mm; the plurality of second metal wires are arranged at equal intervals, with the spacing between two adjacent second metal wires being 1 to 3 mm.

7. The photovoltaic cell unit according to claim 1 or 2, characterized in that, The line width of the first metal wire and the second metal wire is 0.05 to 0.2 mm.

8. The photovoltaic cell unit according to claim 1 or 2, characterized in that, The cross-sectional shape of the first metal wire and the second metal wire is triangular, circular, semi-circular, trapezoidal or rectangular.

9. The photovoltaic cell unit according to claim 1 or 2, characterized in that, The first and second metal wires have triangular cross-sectional shapes, with the chamfer R at the vertex of the triangle ≤ 0.03 mm, the base angles of the triangle all > 45°, and the width of the base of the triangle is 0.05 to 0.2 mm.

10. The photovoltaic cell unit according to claim 1 or 2, characterized in that, The distance between the first conductive connecting strip and the battery cell is no greater than 5mm; the distance between the second conductive connecting strip and the battery cell is no greater than 5mm.

11. The photovoltaic cell unit according to claim 1 or 2, characterized in that, The cross-sectional shape of the first conductive connecting strip and the second conductive connecting strip is triangular, circular, semi-circular, trapezoidal, rectangular or serrated.

12. The photovoltaic cell unit according to claim 1 or 2, characterized in that, The reflective structure is a triangular sawtooth structure, with the apex angle of the sawtooth being 90 to 140 degrees and the chamfer R of the apex angle being ≤0.05mm.

13. The photovoltaic cell unit according to claim 2, characterized in that, The thickness of the ultrathin seed layer is ≤5μm.

14. The photovoltaic cell unit according to claim 2, characterized in that, The first metal wire is fixed to the ultrathin seed layer it is in using a conductive connecting material; the second metal wire is fixed to the ultrathin seed layer it is in using a conductive connecting material.

15. The photovoltaic cell unit according to claim 2, characterized in that, The first metal wire is fixed to the ultrathin seed layer it is in by welding, conductive curing adhesive or conductive tape; the second metal wire is fixed to the ultrathin seed layer it is in by welding, conductive curing adhesive or conductive tape.

16. A method for preparing a photovoltaic module, characterized in that, It employs the photovoltaic cell unit according to any one of claims 1 to 15, and includes the following steps: 1) Laying photovoltaic panels and front-side adhesive film; 2) Grab the photovoltaic cell units and lay them flat on the front film according to the module circuit connection structure to form a cell string; and in a single cell string, the first conductive connecting strip of the photovoltaic cell unit is stacked on the second conductive connecting strip of the adjacent photovoltaic cell unit; at this time, the first metal wire on the bottom surface of the first conductive connecting strip and the second metal wire on the top surface of the second conductive connecting strip are sandwiched between the first conductive connecting strip and the second conductive connecting strip; the stacked first conductive connecting strip and the second conductive connecting strip form a conductive connecting strip pair; 3) Weld the busbars and electrode leads; 4) Lay the backing film and photovoltaic backsheet; at this point, the laminate to be laminated is formed; 5) Place the laminated parts into a laminator for lamination, so that the laminated parts are bonded into a whole; and during the lamination process, the electrical connection material between the conductive connecting strip pairs melts, and the conductive connecting strip pairs and the first metal wire and the second metal wire between the conductive connecting strip pairs are fixed together; 6) Install the junction box and component frame.

17. A method for preparing a photovoltaic module, characterized in that, It employs the photovoltaic cell unit according to any one of claims 1 to 15, and includes the following steps: 1) Laying photovoltaic panels and front-side adhesive film; 2) Grab the photovoltaic cell units and lay them flat on the front film according to the module circuit connection structure to form a cell string; and in a single cell string, the first conductive connecting strip of the photovoltaic cell unit is stacked on the second conductive connecting strip of the adjacent photovoltaic cell unit; at this time, the first metal wire on the bottom surface of the first conductive connecting strip and the second metal wire on the top surface of the second conductive connecting strip are sandwiched between the first conductive connecting strip and the second conductive connecting strip; the stacked first conductive connecting strip and the second conductive connecting strip form a conductive connecting strip pair; 3) Heat the electrical connector between the conductive connector pairs to melt and then solidify it, thus fixing the conductive connector pairs and the first and second metal wires between them together. 4) Weld the busbars and electrode leads; 5) Lay the backing film and photovoltaic backsheet; at this point, the laminate to be laminated is formed; 6) Place the laminated parts into a laminator for lamination, so that the laminated parts are bonded together as a whole; 7) Install the junction box and component frame.

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