Busbar-free heterojunction solar cell and assembly thereof

Abstract

A busbar-free heterojunction solar cell, comprising a cell body and a plurality of parallel finger electrodes arranged on the front and back sides of the cell body, wherein each finger electrode comprises a plurality of first finger electrodes, a second finger electrode is arranged between every two adjacent first finger electrodes, two ends of each second finger electrode are respectively in lap-joint with two first finger electrodes adjacent to the second finger electrode, and a soldering positioning recess is formed in the middle of each second finger electrode. The solar cell structure can not only ensure good conductive performance of finger electrodes, but also take into account good soldering performance of the finger electrodes.

Description

A busbar-free heterojunction solar cell and its assembly

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese invention patent application No. 202321591766.2 filed on June 21, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to the technical field of solar cell modules, and in particular to a busbar-less heterojunction solar cell and a module thereof. Background Art

[0004] A solar cell is a photoelectric conversion semiconductor device, typically composed of one or more semiconductor materials that absorb sunlight and convert it into electricity, combined to form a homojunction or heterojunction diode structure. The semiconductor material absorbs ambient sunlight to generate electrons and holes, commonly known as photogenerated carriers. After separation by the diode's built-in electric field, the electrons and holes accumulate in the n-type and p-type semiconductor regions, respectively, forming an electric potential. To effectively transport the electrons and holes to an external circuit, metal electrodes are typically formed on the front surface (the first light-receiving surface) and the back surface (the second light-receiving surface). The metal electrodes form good electrical contact with the semiconductor material, effectively transporting the photogenerated carriers to the external circuit.

[0005] Heterojunction (HJT) cells are primarily constructed by depositing intrinsic α-Si:H layers on the front and back sides of an n-type silicon wafer. P-type and n-type α-Si:H layers are then fabricated separately, followed by screen printing and curing with a low-temperature silver paste. In actual production, a transparent conductive oxide (TCO) film can also be deposited on the wafer surface before metallization. These heterojunction solar cells are a new and highly efficient cell technology that combines the advantages of both single-crystalline and amorphous silicon solar cells, boasting low fabrication temperatures, high conversion efficiency, and excellent high-temperature characteristics. Due to their low temperature degradation coefficient and bifacial power generation, heterojunction solar cells have significant market potential and have become a key area of ​​research and breakthrough within the industry.

[0006] The photovoltaic industry has developed rapidly amid the energy crisis. The key to further promoting photovoltaic applications is to improve the photoelectric conversion efficiency of solar cells and reduce the production cost of cells.

[0007] Multi-busbar cell and module technology involves placing multiple, larger solder joints on the busbars, with the connecting wires outside the joints designed to be thinner than the busbars. While this approach can reduce silver consumption and busbar shading of the light-receiving surface, silver paste consumption remains high. A single M10 (182mm*182mm) heterojunction solar cell consumes over 140mg of silver paste, still higher than conventional crystalline silicon solar cells. Furthermore, the large busbars increase the shading area, necessitating further improvements to the structure and process of the metal electrodes to reduce the high silver consumption and efficiency losses caused by light shading. To reduce busbar shading of the cell surface and further reduce electrode manufacturing costs, busbar-less cell technology has become a hot topic of research.

[0008] The current busbar-free cells directly remove the busbars on the front and back of the solar cell (as shown in Figure 1). However, due to the small contact point between the welding ribbon and the secondary grid line, it is easy to cause abnormal conditions such as welding deviation, cold welding (unqualified welding tension) or welding failure. At the same time, because the thin grid lines focus on current collection, the selection of slurry will focus on conductive properties, which will reduce the adhesion between the slurry and the surface of the battery body and the interconnecting ribbon. This problem is more serious in heterojunction solar cells made by low-temperature processes.

[0009] Summary of the Invention

[0010] In view of the above analysis, the present disclosure aims to provide a busbar-less heterojunction solar cell and its components to solve the problem of poor welding performance of existing busbar-less heterojunction solar cells.

[0011] The purpose of this disclosure is mainly achieved through the following technical solutions:

[0012] A busbar-less heterojunction solar cell comprises a cell body and a plurality of mutually parallel fine grid electrodes arranged on the front and back sides of the cell body, wherein each of the fine grid electrodes comprises a plurality of first fine grid electrodes, and the plurality of first fine grid electrodes are distributed discontinuously on a straight line, a second fine grid electrode is provided between two adjacent first fine grid electrodes, the two ends of the second fine grid electrode are respectively overlapped with the two adjacent first fine grid electrodes, and a welding positioning groove is formed in the middle portion of the second fine grid electrode.

[0013] Furthermore, the first fine gate electrode and the second fine gate electrode use different metal pastes.

[0014] Furthermore, the first fine grid electrode has a better conductivity than the second fine grid electrode. Furthermore, the adhesion between the second fine grid electrode and the battery body is greater than the adhesion between the first fine grid electrode and the battery body.

[0015] Furthermore, the width of the second fine gate electrode is not less than the width of the first fine gate electrode.

[0016] Furthermore, the distance between two adjacent first fine gate electrodes is 0.1 mm to 3.0 mm. Furthermore, the overlapping length between the first fine gate electrode and the second fine gate electrode is 0.01 mm to 0.1 mm.

[0017] Furthermore, the battery body includes a silicon substrate, a first intrinsic silicon-containing film, a first conductivity type doped silicon-containing film and a first transparent conductive film arranged on the front side of the silicon substrate, and a second intrinsic silicon-containing film, a second conductivity type doped silicon-containing film and a second transparent conductive film arranged on the back side of the silicon substrate.

[0018] A busbar-free heterojunction solar cell assembly comprises a plurality of solar cells according to the above technical solution and an interconnecting ribbon connecting the plurality of solar cells.

[0019] Furthermore, the connection point between the interconnection strap and the fine gate electrode is located in the welding positioning groove, and the interconnection strap is welded to the second fine gate electrode. The present disclosure can achieve at least one of the following beneficial effects:

[0020] (1) The solar cell disclosed in the present invention utilizes two printing steps to print a first fine grid having good electrical conductivity and a second fine grid having good welding performance and adhesion for connecting the first fine grid. This structure can ensure good electrical conductivity of the fine grid electrode while also taking into account good welding performance of the fine grid electrode.

[0021] (2) The solar cell disclosed herein utilizes a welding positioning groove formed by a height difference structure generated by the stacking of the first fine grid and the second fine grid to prevent welding and lamination offset, thereby further improving the welding performance of the main grid-free heterojunction cell and the yield rate of the cell assembly.

[0022] In the present disclosure, the above-mentioned technical solutions can be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present disclosure will be described in the subsequent description, and some advantages will become apparent from the description or be understood through practice of the present disclosure. The objectives and other advantages of the present disclosure can be achieved and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings are only for purposes of illustrating particular embodiments and are not to be considered limiting of the present disclosure. Like reference characters designate like components throughout the drawings.

[0024] FIG1 is a schematic structural diagram of a busbar-free heterojunction solar cell in the prior art;

[0025] FIG2 is a schematic structural diagram of a busbar-less heterojunction solar cell according to an embodiment of the present disclosure;

[0026] FIG3 is a partial enlarged view of portion A of FIG2 ; FIG4 is a front view of FIG3 ;

[0027] FIG5 is a schematic structural diagram of a busbar-less heterojunction solar cell assembly according to an embodiment of the present disclosure;

[0028] FIG6 is a partially enlarged cross-sectional schematic diagram of portion B of FIG5 .

[0029] Reference numerals: 10 - battery body, 20 - fine grid electrode, 21 - first fine grid electrode, 22 - second fine grid electrode, 30 - welding positioning groove, 40 - interconnection ribbon. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present disclosure are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present disclosure and are used together with the embodiments of the present disclosure to illustrate the principles of the present disclosure, and are not used to limit the scope of the present disclosure.

[0031] As shown in Figure 1, the existing busbar-less heterojunction battery directly removes the busbars on the front and back of the solar cell, and welds the interconnecting ribbons and the secondary grid lines to connect multiple battery cells to form a battery module. However, since the secondary grid lines are relatively thin and the contact points between the interconnecting ribbons and the secondary grid lines are small, abnormal situations such as biased welding, cold welding or inability to weld are prone to occur. The welding performance of the battery cells is poor, resulting in a low yield rate of the battery module.

[0032] Example 1

[0033] In view of the above analysis, an embodiment of the present disclosure, as shown in Figure 2, discloses a main grid-free heterojunction solar cell, including a battery body 10 and a plurality of mutually parallel fine grid electrodes 20 arranged on the front and back sides of the battery body 10, each fine grid electrode 20 includes a plurality of first fine grid electrodes 21, and the plurality of first fine grid electrodes 21 are distributed in a straight line and discontinuously, and a second fine grid electrode 22 is provided between two adjacent first fine grid electrodes 21, and the first fine grid electrode 21 and the second fine grid electrode 22 are printed on the battery body 10 twice, and the two ends of the second fine grid electrode 22 are respectively overlapped with the two adjacent first fine grid electrodes 21.

[0034] In this embodiment, as shown in FIG4 , because the two ends of the second fine grid electrode 22 overlap with two adjacent first fine grid electrodes 21, the ends of the second fine grid electrode 22 where they overlap with the first fine grid electrode 21 are higher than the middle portion of the second fine grid electrode 22, forming a welding positioning groove 30 in the middle of the second fine grid electrode 22. The interconnecting ribbon 40 is arranged perpendicular to the fine grid electrode 20 and is located within the welding positioning groove 30, thereby connecting multiple fine grid electrodes 20. In addition, the welding positioning groove 30 provides a positioning and welding point for the interconnecting ribbon 40, preventing welding and lamination offset, improving the welding performance of the busbar-less heterojunction solar cell, and thus increasing the yield rate of the battery module.

[0035] Furthermore, as shown in FIG. 3 , the width L2 of the second fine gate electrode 22 is not less than the width L1 of the first fine gate electrode 21 to ensure the reliability of the connection between the second fine gate electrode 22 and the first fine gate electrode 21 , and between the second fine gate electrode 22 and the interconnection ribbon 40 .

[0036] Furthermore, the first fine gate electrode 21 and the second fine gate electrode 22 use different metal pastes.

[0037] Furthermore, the adhesion between the second fine gate electrode 22 and the battery body 10 and / or the interconnecting tape 40 is greater than the adhesion between the first fine gate electrode 21 and the battery body 10 and / or the interconnecting tape 40, and the conductivity of the first fine gate electrode 21 is better than that of the second fine gate electrode 22. The first fine gate electrode 21 and the second fine gate electrode 22 are printed twice, which can ensure the good conductivity of the fine gate electrode 20 while taking into account the welding performance of the fine gate electrode 20.

[0038] Furthermore, as shown in FIG4 , the interval W1 between two adjacent first fine gate electrodes 21 is 0.1 mm-3.0 mm, and the overlapping length W2 between the first fine gate electrode 21 and the second fine gate electrode 22 is 0.01 mm-0.1 mm.

[0039] In this embodiment, the battery body 10 includes a silicon substrate, a first intrinsic silicon-containing film, a first conductive type doped silicon-containing film and a first transparent conductive film arranged on the front side of the silicon substrate, and a second intrinsic silicon-containing film, a second conductive type doped silicon-containing film and a second transparent conductive film arranged on the back side of the silicon substrate.

[0040] Furthermore, the first intrinsic silicon-containing film and / or the second intrinsic silicon-containing film is a single layer with the same properties or a multilayer with different properties or a stacked or mixed silicon-containing film of microcrystalline, nano, amorphous silicon, silicon oxide or silicon carbide.

[0041] Preferably, the thickness of the first intrinsic silicon-containing thin film and / or the second intrinsic silicon-containing thin film is 1-50 nm.

[0042] Furthermore, the second conductive type doped silicon-containing film and / or the first conductive type doped silicon-containing film is a single layer with the same properties or a multilayer with different properties or a stacked or mixed silicon-containing film of microcrystalline, nano, amorphous silicon, silicon oxide or silicon carbide or other thin film layers.

[0043] Preferably, the thickness of the second conductivity type doped silicon-containing film and / or the first conductivity type doped silicon-containing film is 1-50 nm.

[0044] Furthermore, the first transparent conductive film and / or the second transparent conductive film is a multilayer or stacked layer or a mixture of one or more doped metal oxides or nitrides.

[0045] Furthermore, the metal oxide is one or more of indium oxide, tin oxide, zinc oxide, cadmium oxide or titanium nitride, the metal nitride is titanium nitride, and the doping element is one or more of indium, tin, calcium, aluminum, cadmium, zinc, cerium or fluorine.

[0046] Preferably, the thickness of the first transparent conductive film and / or the second transparent conductive film is 1-100 nm.

[0047] Example 2

[0048] One embodiment of the present disclosure, as shown in FIG5 , discloses a busbar-less heterojunction solar cell assembly, comprising a plurality of solar cells of Example 1 and an interconnecting ribbon 40 connecting the plurality of solar cells. As shown in FIG6 , the connection point between the interconnecting ribbon 40 and the fine grid electrode 20 is located within the welding positioning groove 30 and is welded to the second fine grid electrode 22 to connect the plurality of solar cells to form a solar cell assembly.

[0049] Compared with the prior art, the beneficial effects of the busbar-less heterojunction solar cell module provided in this embodiment are substantially the same as the beneficial effects of the busbar-less heterojunction solar cell provided in Example 1, and are not described in detail here.

[0050] The above description is only a preferred specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or replacements that can be easily conceived by any technician familiar with this technical field within the technical scope disclosed in this disclosure should be covered by the protection scope of the present disclosure.

Claims

1. A busbar-free heterojunction solar cell, comprising a cell body (10) and a plurality of mutually parallel fine grid electrodes arranged on the front and back sides of the cell body (10) (20), each of the fine gate electrodes (20) comprises a plurality of first fine gate electrodes (21), the plurality of the first fine gate electrodes (21) are arranged in a straight line and are distributed discontinuously, a second fine gate electrode (22) is arranged between two adjacent first fine gate electrodes (21), two ends of the second fine gate electrode (22) are respectively overlapped with two adjacent first fine gate electrodes (21), and a welding positioning groove (30) is formed in the middle portion of the second fine gate electrode (22).

2. The busbar-free heterojunction solar cell according to claim 1, wherein: The first fine gate electrode (21) and the second fine gate electrode (22) use different metal pastes.

3. The busbar-free heterojunction solar cell according to claim 2, wherein: The first fine gate electrode (21) has a better conductivity than the second fine gate electrode (22).

4. The busbar-free heterojunction solar cell according to claim 2, wherein: The adhesion force between the second fine grid electrode (22) and the battery body (10) is greater than the adhesion force between the first fine grid electrode (21) and the battery body (10).

5. The busbar-free heterojunction solar cell according to claim 1, wherein: The width of the second fine gate electrode (22) is not less than the width of the first fine gate electrode (21).

6. The busbar-free heterojunction solar cell according to claim 1, wherein: The distance between two adjacent first fine gate electrodes (21) is 0.1 mm-3.0 mm.

7. The busbar-free heterojunction solar cell according to claim 1, wherein: The first fine gate electrode (21) and the second fine gate electrode (22) are overlapped The connection length is 0.01mm-0.1mm.

8. The busbar-free heterojunction solar cell according to any one of claims 1 to 7, wherein: The battery body (10) comprises a silicon substrate, a first intrinsic silicon-containing film, a first conductivity type doped silicon-containing film and a first transparent conductive film arranged on the front side of the silicon substrate, and a second intrinsic silicon-containing film, a second conductivity type doped silicon-containing film and a second transparent conductive film arranged on the back side of the silicon substrate.

9. A busbar-free heterojunction solar cell module, comprising a plurality of solar cells according to any one of claims 1 to 8 and an interconnection ribbon (40) connecting the plurality of solar cells.

10. The busbar-free heterojunction solar cell module according to claim 9, wherein: The connection point between the interconnection ribbon (40) and the fine gate electrode (20) is located in the welding positioning groove (30), and the interconnection ribbon (40) and the second fine gate electrode (22) are welded.

Images