Photovoltaic module

Abstract

The invention provides a photovoltaic module which comprises a battery string, the battery string comprises a plurality of battery pieces, each battery piece comprises an N-type silicon substrate, the N-type silicon substrate is provided with a first face and a second face, the first face comprises a first area and a second area which are distributed in a staggered mode, the first area is provided with a boron-doped polycrystalline silicon layer, and the second face comprises a third area and a fourth area which are distributed in a staggered mode. The third region is provided with a tunneling oxide layer and a phosphorus-doped conductive layer; the battery piece is provided with a first surface and a second surface, and the battery piece comprises a first electrode arranged on the first surface and a second electrode arranged on the second surface; the plurality of first battery pieces and the plurality of second battery pieces are alternately arranged, and the first surfaces of the first battery pieces and the second surfaces of the second battery pieces are located on the same side; the first electrode of the first battery piece is connected with the second electrode of the adjacent second battery piece through the welding strip, and the second electrode of the first battery piece is connected with the first electrode of the adjacent second battery piece through the welding strip, so that the photoelectric conversion efficiency and the output power of the photovoltaic module can be improved.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to a photovoltaic module. Background Art

[0002] Solar energy is an inexhaustible renewable energy source for human beings. Photovoltaic modules are the core and most important part of solar power generation systems. Their function is to convert solar energy into electrical energy and store it in batteries or drive loads. Photovoltaic modules usually include battery strings, which are composed of multiple battery cells connected in series.

[0003] In existing battery strings, the distance between two adjacent battery cells is relatively large, resulting in a small power generation per unit area of ​​the photovoltaic module and a problem of low photoelectric conversion efficiency. Summary of the invention

[0004] In view of this, the present application provides a photovoltaic module to solve the problem of low photoelectric conversion efficiency of photovoltaic modules in the prior art.

[0005] The embodiment of the present application provides a photovoltaic module, including a battery string, the battery string including a plurality of battery cells, the battery cell including an N-type silicon substrate, the N-type silicon substrate having a first surface and a second surface relatively distributed along a thickness direction thereof, the first surface including a first region and a second region distributed alternately, the first region being provided with a boron-doped polysilicon layer, the second surface including a third region and a fourth region distributed alternately, the third region being provided with a stacked tunneling oxide layer and a phosphorus-doped conductive layer; the battery cell having a first surface and a second surface relatively distributed along a thickness direction thereof, the battery cell including a first electrode disposed on the first surface, the first electrode being only located in the first region and being electrically connected to the boron-doped polysilicon layer; the electrode The cell sheet also includes a second electrode arranged on the second surface, the second electrode is only located in the third area and is electrically connected to the phosphorus-doped conductive layer; the battery cell includes a first battery cell and a second battery cell, a plurality of the first battery cells and a plurality of the second battery cells are alternately arranged in the length direction of the battery string, and along the thickness direction of the battery string, the first surface of the first battery cell and the second surface of the second battery cell are located on the same side; the battery string also includes a welding strip, the first electrode of the first battery cell is electrically connected to the second electrode of the adjacent second battery cell through the welding strip, and the second electrode of the first battery cell is electrically connected to the first electrode of the adjacent second battery cell through the welding strip.

[0006] In a possible implementation manner, a distance between any first battery cell and an adjacent second battery cell is less than 1 mm.

[0007] In a possible implementation, the welding strip includes a plurality of first welding strips arranged at intervals along the length direction of the battery string, and the first electrode of the first battery cell is connected to the second electrode of the adjacent second battery cell through the first welding strip; the welding strip also includes a plurality of second welding strips arranged at intervals along the length direction of the battery string, and the second electrode of the first battery cell is connected to the first electrode of the adjacent second battery cell through the second welding strip.

[0008] In a possible implementation, the first electrode includes a first main grid and a first sub-grid, and the second electrode includes a second main grid and a second sub-grid; the extension direction of the first welding strip is parallel to the extension directions of the first main grid and the second main grid, and the first welding strip is used to connect the first main grid of the first battery cell and the second main grid of the adjacent second battery cell; the extension direction of the second welding strip is parallel to the extension directions of the first main grid and the second main grid, and the second welding strip is used to connect the second main grid of the first battery cell and the first main grid of the adjacent second battery cell.

[0009] In a possible implementation, the battery cell is a main grid-less battery, the first electrode includes a first auxiliary grid, and the second electrode includes a second auxiliary grid; the extension direction of the first welding strip is perpendicular to the extension directions of the first auxiliary grid and the second auxiliary grid, and the first welding strip is used to connect the first auxiliary grid of the first battery cell and the second auxiliary grid of the adjacent second battery cell; the extension direction of the second welding strip is perpendicular to the extension directions of the first auxiliary grid and the second auxiliary grid, and the second welding strip is used to connect the second auxiliary grid of the first battery cell and the first auxiliary grid of the adjacent second battery cell.

[0010] In a possible implementation manner, the phosphorus-doped conductive layer may be one of a phosphorus-doped amorphous silicon layer, a phosphorus-doped single crystal silicon layer, or a phosphorus-doped polycrystalline silicon layer.

[0011] In a possible implementation manner, the first surface is a suede structure; and / or the second surface is a suede structure.

[0012] In a possible implementation, the cell further includes a first passivation layer and a first anti-reflection layer, the first passivation layer being disposed on a side of the boron-doped polysilicon layer away from the N-type silicon substrate and on the second region, and the first anti-reflection layer being disposed on a side of the first passivation layer away from the N-type silicon substrate.

[0013] In a possible implementation, the cell further includes a second passivation layer and a second anti-reflection layer, the second passivation layer being disposed on a side of the phosphorus-doped conductive layer away from the tunneling oxide layer and on the fourth region, and the second anti-reflection layer being disposed on a side of the second passivation layer away from the N-type silicon substrate.

[0014] In a possible implementation, the photovoltaic module further includes: an encapsulation layer, used to cover the surface of the battery string; and a cover plate, used to cover the surface of the encapsulation layer away from the battery string.

[0015] In the present application, the multiple cells in the battery string are placed alternately on the front and back sides, so that the welding belt can connect two adjacent cells in the same side interconnection mode, thereby reducing the cell spacing between two adjacent cells in the battery string, thereby increasing the number of cells in the battery string without increasing the area of ​​the photovoltaic module, reducing the blank area of ​​the photovoltaic module layout, and increasing the light receiving area of ​​the battery string per unit area, thereby increasing the power generation per unit area of ​​the photovoltaic module, thereby improving the photoelectric conversion efficiency and output power of the photovoltaic module. Moreover, the battery cell in the present application adopts a special structure in which a boron-doped polysilicon layer is set in the first area and a phosphorus-doped conductive layer is set in the third area, so that the double-sided rate of the battery cell can be close to 100%, thereby further improving the photoelectric conversion efficiency of the photovoltaic module, thereby improving the output power of the photovoltaic module. In addition, the welding belt adopts the same side interconnection mode, which can also avoid the bending of the welding belt, reduce the risk of desoldering of the welding belt, and reduce the risk of stress concentration between the welding belt and the edge of the battery cell, which is conducive to improving the reliability of the photovoltaic module, thereby extending the service life of the photovoltaic module.

[0016] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 A schematic diagram of the structure of the photovoltaic module provided for this application; Figure 2 for Figure 1 A schematic diagram of the cross-sectional structure of a battery cell; Figure 3 for Figure 1 A schematic diagram of the structure of the battery string in the first embodiment; Figure 4 for Figure 3 A top view of a battery string in FIG. Figure 5 for Figure 3 A bottom view of a battery string in FIG. Figure 6 for Figure 1A schematic diagram of the structure of the battery string in the second embodiment; Figure 7 for Figure 6 A top view of a battery string in FIG. Figure 8 for Figure 6 Bottom view of the battery string in FIG.

[0019] Reference numerals: 100-battery string; 200-encapsulation layer; 300-cover plate; 10-battery cell; 10A-first surface; 10B-second surface; 10a-first area; 10b - Second area; 10c - third area; 10d-the fourth area; 101- first battery cell; 102- a second battery cell; 20-welding strip; 201-first welding strip; 202- second welding strip; 1-N type silicon substrate; 1a- first side; 1b- Second side; 2-boron-doped polysilicon layer; 3-Phosphorus-doped conductive layer; 4- Tunneling oxide layer; 5- first electrode; 51- first main grid; 52-first secondary grid; 6- second electrode; 61- second main grid; 62-second secondary grid; 7a- first anti-reflection layer; 7b-first passivation layer; 8a- second anti-reflection layer; 8b-Second passivation layer. DETAILED DESCRIPTION

[0020] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0021] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0022] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0023] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0024] The present application embodiment provides a photovoltaic assembly, such as Figure 1 As shown, the photovoltaic module includes a battery string 100, an encapsulation layer 200 and a cover plate 300. The encapsulation layer 200 is used to cover the two side surfaces of the battery string 100 in the thickness direction Z of the photovoltaic module, and the cover plate 300 is used to cover the surface of the encapsulation layer 200 away from the battery string 100. The encapsulation layer 200 can be an organic encapsulation film such as ethylene-vinyl acetate copolymer (EVA) film, polyethylene octene co-elastomer (POE) film, polyethylene terephthalate (PET) film or polyvinyl butyral (PVB). The cover plate 300 can be a cover plate 300 with a light-transmitting function such as a glass cover plate or a plastic cover plate, and the surface of the cover plate 300 facing the encapsulation layer 200 can be a concave-convex surface, thereby increasing the utilization rate of the incident light. The encapsulation layer 200 and the cover plate 300 can ensure that the photovoltaic module has good mechanical strength, reduce the impact of hail impact, wind blowing, mechanical vibration, etc., and the encapsulation process can also improve the sealing of the photovoltaic module, improve its corrosion resistance and safety.

[0025] The photovoltaic module includes a plurality of battery strings 100 electrically connected in series and / or in parallel, and each battery string 100 includes a plurality of battery cells 10 connected in series by welding strips 20. The battery cell 10 may be a whole battery cell, a two-piece battery cell, a three-piece battery cell, or other forms of multi-piece battery cells, which are not limited in this embodiment.

[0026] The structure of the battery cell 10 in this embodiment is as follows Figure 2As shown, the cell 10 includes an N-type silicon substrate 1, and the N-type doping element in the N-type silicon substrate 1 can be one or a combination of pentavalent elements such as phosphorus, arsenic or antimony. The N-type silicon substrate 1 has a first surface 1a and a second surface 1b that are relatively distributed along its thickness direction Z. The first surface 1a can be the light-facing surface of the N-type silicon substrate 1, that is, the side surface facing the light source and used to receive direct sunlight; the second surface 1b can be the backlight surface of the N-type silicon substrate, that is, the side surface facing away from the light source and used to receive sunlight reflected from the ground. Both the first surface 1a and the second surface 1b can receive sunlight and convert light energy into electrical energy.

[0027] The first surface 1a includes a staggered first area 10a and a second area 10b. The first area 10a can be a metallized area on the light-facing surface, that is, the first area 10a is the area where the metal gate line on the light-facing surface is located. For those skilled in the art, the actual width of the first area 10a can be greater than the actual width of the metal gate line. The second area 10b can be a non-metallized area on the light-facing surface, that is, the second area 10b is the area of ​​the first surface 1a other than the first area 10a. The first surface 1a is provided with a boron-doped polysilicon layer 2. The boron-doped polysilicon layer 2 has a different doping element type from the N-type silicon substrate 1. As an emitter, it can form a PN junction with the N-type silicon substrate 1. It can improve the injection efficiency of photogenerated minority carriers, improve the open circuit voltage of the battery cell 10, and increase the short-circuit current of the battery cell 10, thereby improving the photoelectric conversion efficiency of the battery cell 10. Moreover, doping with boron can improve the high temperature resistance of the polysilicon layer, ensure that the cell 10 maintains good electrical properties during high temperature annealing, and enhance the long-term stability of the polysilicon layer, thereby improving the reliability of the cell 10 and extending the service life of the cell 10. Figure 2 As shown, the boron-doped polysilicon layer 2 is only disposed in the first region 10a, which can reduce the parasitic absorption of the second region 10b for incident light, thereby increasing the absorption rate of the first surface 1a for incident light, and further increasing the efficiency of the light-facing surface of the cell 10.

[0028] like Figure 2As shown, along the thickness direction Z of the N-type silicon substrate 1, the surface of the side of the boron-doped polysilicon layer 2 away from the N-type silicon substrate 1 is further provided with a first passivation layer 7a, and the surface of the side of the first passivation layer 7a away from the boron-doped polysilicon layer 2 is further provided with a first anti-reflection layer 7b. The second region 10b is also provided with a first passivation layer 7a and a first anti-reflection layer 7b stacked along the thickness direction Z of the N-type silicon substrate 1, and the surface of the side of the first passivation layer 7a away from the first anti-reflection layer 7b covers the first surface 1a. The first passivation layer 7a in the first region 10a (the first passivation layer 7a on the surface of the boron-doped polysilicon layer 2) and the first passivation layer 7a in the second region 10b can be an integral structure, and the first anti-reflection layer 7b in the first region 10a and the first anti-reflection layer 7b in the second region 10b can be an integral structure. The first passivation layer 7a may include at least one of silicon nitride, silicon oxynitride, titanium oxide and aluminum oxide, which can play a good passivation role, enhance the carrier concentration of the first surface 1a, and improve the short-circuit current and open-circuit voltage of the cell 10, thereby improving the photoelectric conversion efficiency of the solar cell. The first anti-reflection layer 7b uses the thin film interference principle to reduce the reflection of light and increase the incidence rate of light incident on the first surface 1a. The first anti-reflection layer 7b can specifically be a silicon oxide layer or an aluminum oxide layer.

[0029] The second surface 1b includes a third area 10c and a fourth area 10d that are staggered. The third area 10c can be specifically a metallized area of ​​the backlight surface, that is, the third area 10c is the area where the metal grid line of the backlight surface is located. For those skilled in the art, the actual width of the third area 10c can be larger than the actual width of the metal grid line. The fourth area 10d can be specifically a non-metallized area of ​​the backlight surface, that is, the fourth area 10d is the area of ​​the second surface 1b other than the third area 10c. Along the thickness direction Z of the N-type silicon substrate 1 in the direction away from the silicon substrate 1, a tunneling oxide layer 4 and a phosphorus-doped conductive layer 3 are sequentially arranged in the third area 10c. The stacked tunneling oxide layer 4 and the phosphorus-doped conductive layer 3 can form a passivation contact structure, which can improve the efficiency of the phosphorus-doped conductive layer 3 in collecting electrons. Specifically, the tunnel oxide layer 4 may include at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, silicon carbide or magnesium fluoride, amorphous silicon and polycrystalline silicon. The lattice of the tunnel oxide layer 4 may be well matched with the lattice of the N-type silicon substrate 1, so as to chemically passivate the portion of the second surface 1b in the third region 10c, reduce the recombination center of the contact surface between the tunnel oxide layer 4 and the N-type silicon substrate 1, and reduce the recombination rate of carriers at the contact surface between the N-type silicon substrate 1 and the tunnel oxide layer 4. The phosphorus-doped conductive layer 3 may specifically be one of a phosphorus-doped amorphous silicon layer, a phosphorus-doped single crystal silicon layer or a phosphorus-doped polycrystalline silicon layer, and is used to form a field passivation layer on the second surface 1b, which can reduce the minority carrier concentration and realize the selective transmission of the majority carriers, thereby reducing the carrier recombination rate, increasing the voltage of the cell 10, and increasing the short-circuit current of the cell 10, thereby improving the photoelectric conversion efficiency of the cell 10. Moreover, doping with phosphorus can enhance the long-term stability of the doped conductive layer, thereby improving the reliability of the battery cell 10 and extending the service life of the battery cell 10. Figure 2 As shown, the phosphorus-doped conductive layer 3 and the tunnel oxide layer 4 are only arranged in the third region 10c, which can reduce the parasitic absorption of the fourth region 10d for incident light, thereby increasing the absorption rate of the second surface 1b for incident light, and further increasing the efficiency of the backlight surface of the cell 10.

[0030] like Figure 2As shown, along the thickness direction Z of the N-type silicon substrate 1, the surface of the phosphorus-doped conductive layer 3 away from the tunneling oxide layer 4 is further provided with a second passivation layer 8a, and the surface of the second passivation layer 8a away from the phosphorus-doped conductive layer 3 is further provided with a second anti-reflection layer 8b. The fourth area 10d is also provided with a second passivation layer 8a and a second anti-reflection layer 8b stacked along the thickness direction Z of the N-type silicon substrate 1, and the surface of the second passivation layer 8a away from the second anti-reflection layer 8b covers the second surface 1b. The second passivation layer 8a in the third area 10c (the second passivation layer 8a on the surface of the phosphorus-doped conductive layer 3) and the second passivation layer 8a in the fourth area 10d can be an integral structure, and the second anti-reflection layer 8b in the third area 10c and the second anti-reflection layer 8b in the fourth area 10d can be an integral structure. Among them, the second passivation layer 8a may include at least one of silicon nitride, silicon oxynitride, titanium oxide and aluminum oxide, which can play a good passivation role, enhance the carrier concentration of the second surface 1b, and improve the short-circuit current and open-circuit voltage of the battery cell 10, thereby improving the photoelectric conversion efficiency of the solar cell. The second anti-reflection layer 8b uses the principle of thin film interference to reduce the reflection of light and increase the incidence rate of light incident on the second surface 1b. The second anti-reflection layer 8b can specifically be a silicon oxide layer or an aluminum oxide layer.

[0031] In a specific embodiment, the first surface 1a and / or the second surface 1b is a velvet structure. When the first surface 1a is a pyramid-shaped velvet structure, it can reduce the reflectivity of the first surface 1a to the incident light and increase the absorption utilization rate of the first surface 1a to the light, thereby increasing the light transmittance of the first surface 1a, and then improving the photoelectric conversion efficiency of the battery cell 10. Similarly, when the second surface 1b is a pyramid velvet structure, it can reduce the reflectivity of the second surface 1b to the incident light and increase the absorption utilization rate of the second surface 1b to the light, further improving the photoelectric conversion efficiency of the battery cell 10, and also improving the double-sidedness of the battery cell 10. Moreover, the velveting process can enhance the mechanical strength and durability of the N-type silicon substrate 1, reduce the performance degradation caused by surface defects, and thus improve the long-term stability and reliability of the battery cell 10.

[0032] In addition, if the first surface 1a is textured only, the front side of the cell 10 will be matte dark blue or blue-black, and the back side will be reflective light blue. If the front and back sides of the multiple cells 10 in the photovoltaic module are arranged alternately, it will not be aesthetically pleasing. When both the first surface 1a and the second surface 1b are velvet structures, it can ensure that the light-facing side and the back-facing side of the cell 10 present similar colors. Even if the cells 10 in the photovoltaic module are arranged alternately on the front and back sides, the color consistency of the photovoltaic module can be maintained, thereby improving the aesthetics of the photovoltaic module.

[0033] like Figure 2As shown, the cell 10 has a first surface 10A and a second surface 10B which are relatively distributed along the thickness direction Z thereof. The first surface 10A is specifically the light-facing surface of the cell 10 and is located on the same side as the first surface 1a of the N-type silicon substrate 1. The second surface 10B is specifically the backlight surface of the cell 10 and is located on the same side as the second surface 1b of the N-type silicon substrate 1. The cell 10 includes a first electrode 5 arranged on the first surface 10A and a second electrode 6 arranged on the second surface 10B. The first electrode 5 is specifically the positive electrode of the cell 10 and the second electrode 6 is specifically the negative electrode of the cell 6. The first electrode 5 is located in the first area 10a, and at least part of the structure of the first electrode 5 can penetrate the first anti-reflection layer 7b and the first passivation layer 7a and form an electrical connection with the boron-doped polysilicon layer 2. That is to say, the first electrode 5 and the boron-doped polysilicon layer 2 are only arranged in the first area 10a. The boron-doped polysilicon layer 2 can improve the conductivity and ensure that a good ohmic contact is formed between the first electrode 5 and the N-type silicon substrate 1, thereby reducing the series resistance. The second electrode 6 is located in the third region 10c, and at least a portion of the structure of the second electrode 6 can penetrate the second anti-reflection layer 8b and the second passivation layer 8a and form an electrical connection with the phosphorus-doped conductive layer 3, that is, the passivation contact structure composed of the phosphorus-doped conductive layer 3 and the tunneling oxide layer 4 and the second electrode 6 are only arranged in the third region 10c, and the passivation contact structure ensures that a good ohmic contact is formed between the second electrode 6 and the N-type silicon substrate 1, thereby reducing the series resistance.

[0034] In this embodiment, the battery cell 10 includes a first battery cell 101 and a second battery cell 102. Figure 3 As shown, along the length direction X of the battery string 100, each battery string 100 includes a plurality of first battery cells 101 and a plurality of second battery cells 102 arranged alternately. Among them, along the thickness direction Z of the battery string 100, the first surface 10A of the first battery cell 101 and the second surface 10B of the second battery cell 102 are located on the same side. That is, the placement directions of the first battery cell 101 and the second battery cell 102 are opposite. The first electrode 5 of the first battery cell 101 and the second electrode 6 of the adjacent second battery cell 102 are electrically connected through the welding strip 20, and the second electrode 6 of the first battery cell 101 and the first electrode 5 of the adjacent second battery cell 102 are electrically connected through the welding strip 20. The welding strip 20 includes a plurality of first welding strips 201 arranged at intervals along the length direction X of the battery string 100 and a plurality of second welding strips 201 arranged at intervals along the length direction X of the battery string 100, and the first welding strips 201 and the second welding strips 202 are respectively located on the two side surfaces of the thickness direction Z of the battery string 100. The first electrode 5 of the first battery cell 101 is connected to the second electrode 6 of the adjacent second battery cell 102 via the first welding strip 201 , and the second electrode 6 of the first battery cell 101 is connected to the first electrode 5 of the adjacent second battery cell 102 via the second welding strip 202 .

[0035] Specifically, Figure 3 As shown, taking the battery string 100 including 6 battery cells 10 as an example, along the length direction X of the battery string 100, the first battery cell 10 is the first battery cell 101, and its first surface 10A is placed upward; the second battery cell 10 is the second battery cell 102, and its second surface 10B is placed upward; the third battery cell 10 is the first battery cell 101, and its first surface 10A is placed upward; the fourth battery cell 10 is the second battery cell 102, and its second surface 10B is placed upward; the fifth battery cell 10 is the first battery cell 101, and its first surface 10A is placed upward; the sixth battery cell 10 is the second battery cell 101, and its second surface 10B is placed upward. The first electrode 5 of the first battery cell 10 is electrically connected to the second electrode 6 of the second battery cell 10 through the first welding strip 201, the first electrode 5 of the second battery cell 10 is electrically connected to the second electrode 6 of the third battery cell 10 through the second welding strip 202, the first electrode 5 of the third battery cell 10 is electrically connected to the second electrode 6 of the fourth battery cell 10 through the first welding strip 201, the first electrode 5 of the fourth battery cell 10 is electrically connected to the second electrode 6 of the fifth battery cell 10 through the second welding strip 202, and the first electrode 5 of the fifth battery cell 10 is electrically connected to the second electrode of the sixth battery cell 10 through the first welding strip 201, thereby forming a complete battery string 100.

[0036] It should be noted that when the battery string 100 includes more battery cells 10, they are also arranged in the above manner, and this embodiment does not limit the specific number of battery cells 10 in the battery string 100. The first battery cell 101 and the second battery cell 102 have the same internal structure, and only have different placement directions.

[0037] In the photovoltaic module provided in this embodiment, the plurality of cells 10 in the cell string 100 are placed alternately on the front and back sides, so that the welding strip 20 can connect two adjacent cells 10 in the same side interconnection mode, thereby reducing the cell spacing between two adjacent cells 10 in the cell string 100, thereby increasing the number of cells 10 in the cell string 100 without increasing the area of ​​the photovoltaic module, reducing the blank area of ​​the photovoltaic module layout, and increasing the light receiving area of ​​the cell string 100 per unit area, thereby increasing the power generation per unit area of ​​the photovoltaic module, and further improving the photoelectric conversion efficiency and output power of the photovoltaic module. Moreover, the cell 10 in this embodiment adopts a special structure in which the first area 10a is provided with a boron-doped polysilicon layer 2 and the third area 10c is provided with a phosphorus-doped conductive layer 3, so that the bifaciality of the cell can be close to 100%, thereby further improving the photoelectric conversion efficiency of the photovoltaic module, and further improving the output power of the photovoltaic module. In addition, the soldering ribbon 20 is interconnected on the same side, which can prevent the soldering ribbon 20 from bending, reduce the risk of desoldering of the soldering ribbon 20, and reduce the risk of stress concentration between the soldering ribbon 20 and the edge of the battery cell 10, which is beneficial to improving the reliability of the photovoltaic module, thereby extending the service life of the photovoltaic module.

[0038] In this embodiment, since the plurality of cells 10 in the battery string 100 are arranged alternately on the front and back sides, the welding strip 20 can connect two adjacent cells 10 in a same-side interconnection manner, that is, there is no traditional welding strip gap between adjacent cells 10, which can reduce the cell spacing between two adjacent cells 10. Specifically, the spacing between any first cell 101 and the adjacent second cell 102 is less than 1mm. The spacing can specifically be 0mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm or 1mm. When the spacing is 0mm, the dense stacking of the cells 10 can be achieved, maximizing the power generation per unit area of ​​the photovoltaic module, thereby increasing the output power of the photovoltaic module.

[0039] It should be noted that, since absolute zero spacing cannot be achieved in practical applications, as long as the measured value is less than 0.1 mm, the spacing can be regarded as equivalent to 0 mm within the allowable error range of the measurement work.

[0040] In a specific embodiment, the battery cell 10 may be a busbar battery cell, the first electrode 5 includes a first busbar 51 and a first sub-grid 52, the first busbar 51 is specifically a positive busbar, and the first sub-grid 52 is specifically a positive sub-grid; the second electrode 6 includes a second busbar 61 and a second sub-grid 62, the second busbar 61 is specifically a positive busbar, and the second sub-grid 62 is specifically a negative sub-grid. The extension direction of the first welding strip 201 is parallel to the extension direction of the first busbar 51 and the second busbar 61, both of which are the length direction X of the battery string 100, and the first welding strip 201 is used to connect the first busbar 51 of the first battery cell 101 and the second busbar 61 of the adjacent second battery cell 102. The extension direction of the second welding strip 202 is parallel to the extension direction of the first busbar 51 and the second busbar 61, both of which are the length direction X of the battery string 100, and the second welding strip 202 is used to connect the second busbar 61 of the first battery cell 101 and the first busbar 51 of the adjacent second battery cell 102. Among them, along the width direction Y of the battery string 100, the first surface 10A of the battery cell 10 includes a plurality of first main grids 51 arranged at intervals, and the second surface 10B of the battery cell 10 includes a plurality of second main grids 61 arranged at intervals, and the number of first welding strips 201 and second welding strips 202 should be consistent with the number of first main grids 51 and second main grids 61, so as to ensure the collection effect of the first welding strips 201 and the second welding strips 202 on the current in the battery cell 10.

[0041] In another specific embodiment, the battery cell 10 may be a busbar-free battery cell, the first electrode 5 only includes the first auxiliary grid 52, and the second electrode 6 only includes the second auxiliary grid 62. The extension direction of the first welding strip 201 is perpendicular to the extension direction of the first auxiliary grid 52 and the second auxiliary grid 62, the extension direction of the first welding strip 201 is the length direction X of the battery string 100, the extension direction of the first auxiliary grid 52 and the second auxiliary grid 62 is the width direction Y of the battery string 100, and the first welding strip 201 is used to connect the first auxiliary grid 52 of the first battery cell 101 and the second auxiliary grid 62 of the adjacent second battery cell 102. The extension direction of the second welding strip 202 is perpendicular to the extension direction of the first auxiliary grid 52 and the second auxiliary grid 62, the extension direction of the second welding strip 202 is the length direction X of the battery string 100, the extension direction of the first auxiliary grid 52 and the second auxiliary grid 62 is the width direction Y of the battery string 100, and the second welding strip 202 is used to connect the second auxiliary grid 62 of the first battery cell 101 and the first auxiliary grid 52 of the adjacent second battery cell 102. Among them, along the length direction of the battery string 100, the first surface 10A of the battery cell 10 includes a plurality of first sub-grids 52 arranged at intervals, and the second surface 10B of the battery cell 10 includes a plurality of second sub-grids 62 arranged at intervals. When the first welding strip 201 and the second welding strip 202 are connected to the battery cell 10, they should form an electrical connection with each first sub-grid 52 or each second sub-grid 62 on the same battery cell 10. Moreover, along the width direction Y of the battery string 100, multiple first welding strips 201 and multiple second welding strips 202 can be set to enhance the collection effect of the first welding strip 201 and the second welding strip 202 on the current in the battery cell 10.

[0042] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A photovoltaic module, characterized in that: The invention comprises a battery string (100), wherein the battery string (100) comprises a plurality of battery cells (10), wherein the battery cells (10) comprise an N-type silicon substrate (1), wherein the N-type silicon substrate (1) comprises a first surface (1a) and a second surface (1b) which are arranged opposite to each other along a thickness direction thereof, wherein the first surface (1a) comprises a first region (10a) and a second region (10b) which are arranged in an alternating manner, wherein the first region (10a) is provided with a boron-doped polysilicon layer (2), and wherein the second surface (1b) comprises a third region (10c) and a fourth region (10d) which are arranged in an alternating manner, wherein the third region (10c) is provided with a tunneling oxide layer (4) and a phosphorus-doped conductive layer (3) which are arranged in a stacked manner; The cell (10) has a first surface (10A) and a second surface (10B) which are relatively distributed along the thickness direction thereof, the cell (10) comprising a first electrode (5) arranged on the first surface (10A), the first electrode (5) being only located in the first area (10a) and being electrically connected to the boron-doped polysilicon layer (2); the cell (10) further comprises a second electrode (6) arranged on the second surface (10B), the second electrode (6) being only located in the third area (10c) and being electrically connected to the phosphorus-doped conductive layer (3); The battery cell (10) comprises a first battery cell (101) and a second battery cell (102); a plurality of the first battery cells (101) and a plurality of the second battery cells (102) are alternately arranged in the length direction of the battery string (100); and along the thickness direction of the battery string (100), the first surface (10A) of the first battery cell (101) and the second surface (10B) of the second battery cell (102) are located on the same side; The battery string (100) further comprises a welding strip (20), wherein the first electrode (5) of the first battery cell (101) is electrically connected to the second electrode (6) of the adjacent second battery cell (102) via the welding strip (20), and the second electrode (6) of the first battery cell (101) is electrically connected to the first electrode (5) of the adjacent second battery cell (102) via the welding strip (20).

2. The photovoltaic module according to claim 1, characterized in that: The distance between any one of the first battery cells (101) and an adjacent one of the second battery cells (102) is less than 1 mm.

3. The photovoltaic module according to claim 1, characterized in that: The welding strip (20) comprises a plurality of first welding strips (201) arranged at intervals along the length direction of the battery string (100), and the first electrode (5) of the first battery cell (101) is connected to the second electrode (6) of the adjacent second battery cell (102) through the first welding strip (201); The welding strip (20) further comprises a plurality of second welding strips (202) arranged at intervals along the length direction of the battery string (100), and the second electrode (6) of the first battery cell (101) is connected to the first electrode (5) of the adjacent second battery cell (102) via the second welding strips (202).

4. The photovoltaic module according to claim 3, characterized in that: The first electrode (5) comprises a first main grid (51) and a first auxiliary grid (52), and the second electrode (6) comprises a second main grid (61) and a second auxiliary grid (62); The extension direction of the first welding strip (201) is parallel to the extension direction of the first main grid (51) and the second main grid (61), and the first welding strip (201) is used to connect the first main grid (51) of the first battery cell (101) and the second main grid (61) of the adjacent second battery cell (102); The extension direction of the second welding strip (202) is parallel to the extension direction of the first main grid (51) and the second main grid (61), and the second welding strip (202) is used to connect the second main grid (61) of the first battery cell (101) and the first main grid (51) of the adjacent second battery cell (102).

5. The photovoltaic module according to claim 3, characterized in that: The battery cell (10) is a main grid-less battery, the first electrode (5) comprises a first auxiliary grid (52), and the second electrode (6) comprises a second auxiliary grid (62); The extension direction of the first welding strip (201) is perpendicular to the extension directions of the first auxiliary grid (52) and the second auxiliary grid (62), and the first welding strip (201) is used to connect the first auxiliary grid (52) of the first battery cell (101) and the second auxiliary grid (62) of the adjacent second battery cell (102); The extension direction of the second welding strip (202) is perpendicular to the extension direction of the first auxiliary grid (52) and the second auxiliary grid (62), and the second welding strip (202) is used to connect the second auxiliary grid (62) of the first battery cell (101) and the first auxiliary grid (52) of the adjacent second battery cell (102).

6. The photovoltaic module according to claim 1, characterized in that: The phosphorus-doped conductive layer (3) may be one of a phosphorus-doped amorphous silicon layer, a phosphorus-doped single crystal silicon layer or a phosphorus-doped polycrystalline silicon layer.

7. The photovoltaic module according to claim 1, characterized in that: The first surface (1a) is a velvet structure; And / or, the second surface (1b) is a suede structure.

8. The photovoltaic module according to claim 1, characterized in that: The cell (10) further comprises a first passivation layer (7a) and a first anti-reflection layer (7b), wherein the first passivation layer (7a) is arranged on a side of the boron-doped polysilicon layer (2) away from the N-type silicon substrate (1) and on the second region (10b), and the first anti-reflection layer (7b) is arranged on a side of the first passivation layer (7a) away from the N-type silicon substrate (1).

9. The photovoltaic module according to claim 1, characterized in that: The cell (10) further comprises a second passivation layer (8a) and a second anti-reflection layer (8b), wherein the second passivation layer (8a) is arranged on a side of the phosphorus-doped conductive layer (3) away from the tunneling oxide layer (4) and on the fourth region (10d), and the second anti-reflection layer (8b) is arranged on a side of the second passivation layer (8a) away from the N-type silicon substrate (1).

10. The photovoltaic module according to any one of claims 1 to 9, characterized in that: The photovoltaic module further comprises: An encapsulation layer (200), used for covering the surface of the battery string (100); A cover plate (300) is used to cover a surface of the packaging layer (200) away from the battery string (100).

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