Solar cell string, solar cell module and preparation method of solar cell string

Abstract

The present disclosure relates to a solar cell string, a solar cell module, and a method of manufacturing a solar cell string, the solar cell string comprising a wiring member and at least two back contact solar cells, the wiring member connecting the back contact solar cells in series, the wiring component comprises a conductive inner core and an electrically insulated organic weldable protective layer covering the outer surface of the conductive inner core; wherein the back surface of the back contact solar cell is provided with a plurality of dispersed soldering paste points, the organic solderable protection layer is provided with a plurality of openings which are arranged at intervals along the extension direction of the wiring component and are used for exposing local parts of the conductive inner core, and the soldering paste points are in contact with the electrodes and are in contact with the conductive inner core through the openings. The solar cell string disclosed by the invention is relatively low in production cost, relatively excellent in safety and relatively high in yield.

Description

Technical Field

[0001] This application relates to the field of new energy, specifically to a solar cell string, a solar cell module, and a method for preparing the solar cell string. Background Technology

[0002] A back-contact solar cell is a type of solar cell in which the positive and negative electrodes are arranged alternately in an interdigitated pattern on the back of the cell. A back-contact solar cell typically includes finger-shaped collecting electrodes (or fine grids) and bus electrodes (or main grids). The finger-shaped electrodes collect the photocurrent from the cell, and the bus electrodes combine the current collected by the finger-shaped electrodes. Multiple cell bus electrodes are connected in series with wiring components to form a solar cell string. The current from the bus electrodes is then transmitted to the outside of the cell through the wiring components.

[0003] In existing technologies, multiple pads are spaced apart on the bus gate electrode. The wiring components are generally copper core solder strips with a tin coating. The tin layer of the wiring components is fused to the pads, thus mechanically and electrically connecting the wiring components to the bus electrode. During connection, to prevent the wiring components from misaligning and coming into contact with opposite-shaped finger electrodes, causing a short circuit, an insulating layer is applied to both sides of the bus electrode to prevent the wiring components from contacting opposite-shaped finger electrodes and causing a short circuit.

[0004] With fierce competition in the photovoltaic module market, it is urgent to further reduce the manufacturing cost of solar cell modules, avoid short circuits, and improve yield while ensuring product reliability. Summary of the Invention

[0005] The purpose of this disclosure is to provide a solar cell string, a solar cell module, and a method for manufacturing a solar cell string, which has low production cost, superior safety, and high yield.

[0006] To achieve the above objectives, a first aspect of this disclosure provides a solar cell string, including a wiring component and at least two back-contact solar cells, wherein the wiring component connects the back-contact solar cells in series, and the wiring component includes a conductive core and an electrically insulating organic solderable protective layer covering the outer surface of the conductive core; wherein... The back contact solar cell has a plurality of solder paste dots distributed on its back side. The organic solderable protective layer has a plurality of openings spaced apart along the extension direction of the wiring member to expose the conductive core. The solder paste dots are in contact with the electrodes of the back contact solar cell and are in contact with the conductive core through the openings.

[0007] Optionally, according to claim 1, the solar cell string is characterized in that the surfaces other than the surface of the conductive core that contacts the solder paste are electrically insulated and protected by the organic solderability protective layer.

[0008] A second aspect of this disclosure provides a solar cell string, including a wiring member and at least two back-contact solar cells, the wiring member connecting the back-contact solar cells in series, the wiring member including a conductive core and an electrically insulating organic solderable protective layer covering the surface of the conductive core, wherein... The back of the back contact solar cell is provided with a plurality of solder paste dots distributed on the back side. The solder paste dots are in direct contact with the electrodes of the back contact solar cell and a local surface of the conductive core. Except for the local surface of the conductive core that is in contact with the solder paste dots, the other surfaces of the conductive core are covered with the organic solderability protective layer.

[0009] Optionally, the solder paste point is a cured solder paste point, and the solder paste point contains flux.

[0010] Optionally, the organic solderable protective layer is a triazine indene film or an imidazole organic crystalline alkali film.

[0011] Optionally, the conductive core is a bare wire.

[0012] Optionally, the conductive core is a bare copper wire, a bare aluminum wire, a bare nickel wire, or a bare silver wire.

[0013] Optionally, the thickness of the organic solderable protective layer in the wiring component is 0.2-10 μm.

[0014] Optionally, the maximum width of the conductive core is 0.18-0.8 mm.

[0015] Optionally, the cross-section of the conductive inner core is circular, rectangular, or triangular.

[0016] Optionally, the resistivity of the organic solderable protective layer is 10. 7 -10 12 Ω·m.

[0017] Optionally, the back-contact solar cell includes a silicon substrate, a first semiconductor region and a second semiconductor region formed on the back side of the silicon substrate, a first electrode in contact with the first semiconductor region, and a second electrode in contact with the second semiconductor region; The wiring component connects the first electrode of one back-contact battery in series with the second electrode of another back-contact battery.

[0018] Optionally, the first electrode includes a first bus electrode extending along a first direction and a first finger electrode extending along a second direction, and the second electrode includes a second bus electrode extending along the first direction and a second finger electrode extending along the second direction, wherein the first direction intersects the second direction; the first bus electrode and the second bus electrode are alternately arranged in the second direction, and the first finger electrode and the second finger electrode are alternately arranged in the first direction; the first electrode and the second electrode are spaced apart from each other; the first bus electrode and the second bus electrode are respectively provided with a plurality of pads, and the solder paste dots are connected to the pads.

[0019] Optionally, each of the bus electrodes is provided with 5-10 pads spaced apart.

[0020] Optionally, the first semiconductor region includes a first dielectric layer formed on the surface of the silicon substrate and a first doped silicon layer formed on the surface of the first dielectric layer; the second semiconductor region includes a second dielectric layer formed on the surface of the silicon substrate and a second doped silicon layer formed on the surface of the second dielectric layer; the first doped silicon layer and the second doped silicon layer have opposite conductivity types.

[0021] Optionally, the first dielectric layer and the second dielectric layer are tunneling oxide layers, and the first doped silicon layer and the second doped silicon layer are doped polysilicon layers; or, The first dielectric layer and the second dielectric layer are intrinsic amorphous silicon layers, and the first doped silicon layer and the second doped silicon layer are doped amorphous silicon layers; or, The first dielectric layer is a tunneling oxide layer, the first doped silicon layer is a doped polycrystalline silicon layer, the second dielectric layer is an intrinsic amorphous silicon layer, and the second doped silicon layer is a doped amorphous silicon layer.

[0022] A third aspect of this disclosure provides a solar cell module, including the solar cell string provided in the first or second aspect of this disclosure.

[0023] The fourth aspect of this disclosure provides a method for preparing a solar cell string, in which a wiring component with a complete organic solderable protective layer on its surface is brought into contact with solder paste dots disposed on the electrodes of a back-contact solar cell and heated, so that the portion of the organic solderable protective layer in contact with the solder paste dots melts, while the remaining portion not in contact with the solder paste dots is still covered with an electrically insulating organic solderable protective layer.

[0024] Through the above technical solution, the battery string of this disclosure connects multiple back-contact solar cells through wiring components with organic solderable protective layers. This eliminates the need to print insulating adhesive on the cells to avoid short circuits caused by contact between the wiring components and opposite-shaped finger electrodes due to positional deviations. This simplifies the manufacturing process of solar cell strings and improves the safety and product yield of solar cell strings. Attached Figure Description

[0025] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a structural diagram of one specific embodiment of the solar cell string disclosed herein.

[0026] Figure 2 This is a schematic diagram of a specific embodiment of the back-contact solar cell disclosed herein.

[0027] Figure 3 This is a public document Figure 2 The diagram shows a cross-sectional view of the back-contact solar cell along AA.

[0028] Figure 4 This is a cross-sectional view of the wiring component and the back-contact solar cell connection structure disclosed herein.

[0029] Figure 5 This is a structural schematic diagram of a specific embodiment of the wiring component disclosed herein.

[0030] Figure 6 This is a side view of the wiring component and the back-contact solar cell connection structure disclosed herein.

[0031] Explanation of reference numerals in the attached figures 20. Back contact solar cell; 10. Wiring component; 11. Conductive core 12. Organic solderable protective layer 121. Opening 30. Solder paste dot 21. Electrode 21a, First Electrode 21b, second electrode d1, first direction 211, first bus electrode d2, second direction 212, first finger electrode 213, second bus electrode 214. Second finger electrode; 215. Pad; 22. Silicon substrate 23. First semiconductor region; 24. Second semiconductor region; 231. First dielectric layer 232, First doped silicon layer; 241, Second dielectric layer; 242, Second doped silicon layer Detailed Implementation The organic solderability preservative (OSP) is itself insulating; when applied to a conductive metal surface, it prevents oxidation of the conductive metal surface. During thermal soldering, when the OSP comes into contact with solder paste, it is rapidly melted away by the flux in the solder paste, while the portion of the OSP that does not come into contact with the solder paste remains. This disclosure utilizes this property of the OSP to simplify the interconnection of 20 back-contact solar cells in industrial applications.

[0032] The first aspect of this disclosure is to provide a solar cell string. Figure 1 A specific embodiment of the solar cell string of the present disclosure is shown. The solar cell string includes a wiring member 10 and at least two back-contact solar cells 20 arranged along a first direction d1. The wiring member 10 connects the back-contact solar cells 20 in series.

[0033] Figure 2 The diagram illustrates the back side of a back-contact solar cell 20, representing some examples of this disclosure. The electrodes 21 of the back-contact solar cell 20 are disposed on the back side of the cell, i.e., the side facing away from sunlight. For example, please refer to... Figure 2 The back-contact solar cell 20 has a first electrode 21a and a second electrode 21b, which are formed isolated from each other on the back side of the solar cell. The first electrode 21a and the second electrode 21b have opposite polarities; for example, the first electrode 21a is the positive electrode and the second electrode 21b is the negative electrode, or the first electrode 21a is the negative electrode and the second electrode 21b is the positive electrode. A wiring member 10 electrically interconnects the first electrode 21a of one solar cell with the second electrode 21b of another solar cell. That is, one end of the wiring member 10 is electrically connected to the first electrode 21a of one of the back-contact solar cells 20 and electrically insulated from the second electrode 21b of that back-contact solar cell 20, while the other end is electrically connected to the second electrode 21b of another back-contact solar cell 20 and electrically insulated from the first electrode 21a of that back-contact solar cell 20, thereby forming a series circuit structure.

[0034] Please continue to refer to this. Figure 2In some examples, the first electrode 21a of the back-contact solar cell 20 includes a first bus electrode 211 extending along a first direction d1 and a first finger electrode 212 extending along a second direction d2, and the second electrode 21b includes a second bus electrode 213 extending along the first direction d1 and a second finger electrode 214 extending along the second direction d2, the first direction d1 and the second direction d2 intersecting. The first bus electrode 211 and the second bus electrode 213 are alternately arranged in the second direction d2, and the first finger electrode 212 and the second finger electrode 214 are alternately arranged in the first direction d1. The first electrode 21a and the second electrode 21b are spaced apart from each other. A plurality of pads 215 are provided on the first bus electrode 211 and the second bus electrode 213 respectively. For example, 5-10 pads 215 are spaced apart on each bus electrode.

[0035] Figure 3 It indicates along Figure 2 The diagram shows a cross-sectional view of the back-contact solar cell 20 (AA). Please refer to... Figure 3 In some examples, the back-contact solar cell includes a silicon substrate 22 and a first semiconductor region 23 and a second semiconductor region 24 formed on the back side of the silicon substrate 22, a first electrode 21a in contact with the first semiconductor region 23, a second electrode 21b in contact with the second semiconductor region 24, and a wiring member 10 connecting the first electrode 21a of one back-contact solar cell in series with the second electrode 21b of the other back-contact solar cell.

[0036] Further reference Figure 3 The first semiconductor region 23 includes a first dielectric layer 231 formed on the surface of the silicon substrate 22 and a first doped silicon layer 232 formed on the surface of the first dielectric layer 231. The second semiconductor region 24 includes a second dielectric layer 241 formed on the surface of the silicon substrate 22 and a second doped silicon layer 242 formed on the surface of the second dielectric layer 241. The first doped silicon layer 232 and the second doped silicon layer 242 have opposite conductivity types. For example, the first doped silicon layer 232 is P-type conductive and the second doped silicon layer 242 is N-type conductive, or the first doped silicon layer 232 is N-type conductive and the second doped silicon layer 242 is P-type conductive.

[0037] In one embodiment, the first dielectric layer 231 and the second dielectric layer 241 can be tunneling oxide layers, and the first doped silicon layer 232 and the second doped silicon layer 242 can be doped polysilicon layers. In this example, the emitter region and the back surface field region employ a passivated contact structure.

[0038] In one embodiment, the first dielectric layer 231 and the second dielectric layer 241 can be intrinsic amorphous silicon layers, and the first doped silicon layer 232 and the second doped silicon layer 242 can be doped amorphous silicon layers. In this example, the emitter region and the back surface field region employ a heterojunction passivation structure.

[0039] In one embodiment, the first dielectric layer 231 is a tunneling oxide layer, the first doped silicon layer 232 is a doped polycrystalline silicon layer, the second dielectric layer 241 is an intrinsic amorphous silicon layer, and the second doped silicon layer 242 is a doped amorphous silicon layer. In this example, the back contact solar cell adopts a hybrid structure consisting of a passivation contact structure and a heterojunction passivation structure.

[0040] The first aspect of this disclosure provides a solar cell string, Figure 4 A cross-sectional view illustrating the connection structure between the wiring component 10 and the back-contact solar cell 20 is shown. Figure 6 A side view illustrating the connection structure between the wiring component 10 and the back-contact solar cell 20 is shown. The wiring component 10 includes a conductive inner core 11 and an electrically insulating organic solderable protective layer 12 covering the outer surface of the conductive inner core 11. The organic solderable protective layer 12 can be a thin film layer wrapped around the outer surface of the conductive inner core 11. Figure 5 As shown, in the structure of the solar cell string, the organic solderable protective layer 12 has a plurality of partially exposed conductive cores 11 spaced apart along the extension direction of the wiring member 10. On the back side of the back contact solar cell 20, for example along the bus electrode, a plurality of dispersed solder paste dots 30 are provided. The solder paste dots 30 contact the electrode and, through the openings 121, the conductive cores 11. The solder paste dots 30 connect the conductive cores 11 to the electrode of the back contact solar cell 20, attaching the conductive cores 11 to the cell and conducting current between them. In one embodiment, these openings 121 are spaced apart along the length of the wiring member 10 on the organic solderable protective layer 12. The portion between the openings 121 of the organic solderable protective layer 12 is a complete insulating film, exposing portions of the conductive cores 11 to the solder paste dots 30. The surface of the conductive cores 11 between the openings 121 is insulated and protected by the organic solderable protective layer 12, eliminating the need to print insulating adhesive on the cell. For example, when the wiring component 10 is connected to the first electrode 21a of the first back contact solar cell 20, the wiring component 10 will not cause a short circuit even if it is placed on the second electrode 21b of the first back contact solar cell 20, because the surface of the wiring component 10 is protected by the insulating organic solderable protective layer 12.

[0041] A second aspect of this disclosure provides a solar cell string. In some examples, the solar cell string includes a wiring member 10 and at least two back-contact solar cells 20. The wiring member 10 includes a conductive core 11 and an electrically insulating organic solderable protective layer 12 covering the surface of the conductive core 11. The wiring member 10 connects the back-contact cells in series. A plurality of solder paste dots 30 are distributed on the back side of each back-contact cell. The solder paste dots 30 directly contact the electrodes of the back-contact solar cells and a portion of the conductive core 11. Except for the portion of the conductive core 11 in contact with the solder paste dots 30, the other surfaces of the conductive core are covered with the organic solderable protective layer 12. The solder paste dots 30 attach the conductive core 11 to the electrodes of the back-contact solar cells 20 and conduct current between the conductive core 11 and the electrodes. Because the surface of the wiring member 10 between the solder dots is covered with the organic solderable protective layer 12, which is insulating, it eliminates the need to print insulating adhesive on the solar cells.

[0042] This disclosure uses solder paste dots 30 to connect the wiring component 10 to the electrodes of the back contact solar cell 20. During series operation, solder paste can be applied to predetermined positions on the back electrode of the back contact solar cell 20 to form solder paste dots 30. For example, in some examples, solder paste dots 30 can be provided on the pads 215 of the back contact solar cell. The wiring component 10, whose surface is completely covered by an organic solderable protective layer 12, is brought into contact with the solder paste dots 30. During the hot soldering process, the flux in the solder paste dots 30 promotes the melting of the portion of the organic solderable protective layer 12 that is in contact with the solder paste dots 30, thereby making the solder paste dots 30 electrically contact the conductive core 11. The portion of the organic solderable protective layer 12 that is not in contact with the solder paste dots 30 remains on the surface of the conductive core 11.

[0043] In some examples, solder paste point 30 is a cured solder paste point containing flux. Preferably, the solder paste is a paste mixture containing solder powder, flux, other surfactants and thixotropic agents.

[0044] In some examples, the organic solderable protective layer 12 is a triazine indene film or an imidazole organic crystalline base film.

[0045] In some examples, the conductive core 11 is a bare conductor. For example, the conductive core 11 is a bare copper conductor, a bare aluminum conductor, a bare nickel conductor, or a bare silver conductor. Since the conductive core 11 is soldered to the back contact solar cell 20 using solder paste, a flux layer such as tin is not required on the conductive core 11. Furthermore, the organic solderability protective layer 12 protects the bare conductor from oxidation.

[0046] In some examples, the thickness of the organic solderability protective layer 12 in the wiring component 10 is 0.2-10 μm.

[0047] In some examples, the maximum width of the conductive core 11 is 0.18-0.8 mm. The cross-section of the conductive core 11 can be circular, rectangular, or triangular. When the cross-section of the conductive core 11 is circular, the maximum width of the conductive core 11 refers to the diameter of the circle. When the cross-section of the conductive core 11 is rectangular, the maximum width of the conductive core 11 refers to the length of the rectangle. When the cross-section of the conductive core 11 is triangular, the maximum width of the conductive core 11 is the length of the longest side of the triangle.

[0048] In some examples, the resistivity of the organic solderability protective layer 12 is 10. 7 -10 12 Ω·m.

[0049] A third aspect of this disclosure provides a solar cell module that includes a string of solar cells provided in the first or second aspect of this disclosure.

[0050] This disclosure provides a fourth aspect of a method for preparing a solar cell string provided in the first or second aspect of this disclosure. The method includes: contacting and adding solder paste dots 30 disposed on the electrodes of a back-contact solar cell 20 to a wiring component 10 with a complete organic solderable protective layer 12 on its surface, for example by welding, using welding temperature and flux in the solder paste dots 30 to rapidly melt the portion of the organic solderable protective layer 12 in contact with the solder paste dots, while the remaining portion not in contact with the solder paste dots is still covered with an electrically insulating organic solderable protective layer 12.

[0051] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0052] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0053] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A solar cell string, characterized in that, The device includes a wiring component and at least two back-contact solar cells, the wiring component connecting the back-contact solar cells in series, and the wiring component comprising a conductive core and an electrically insulating, organic, solderable protective layer covering the outer surface of the conductive core; wherein, The back contact solar cell has a plurality of solder paste dots dispersed on its back side. The organic solderable protective layer has a plurality of openings spaced apart along the extension direction of the wiring member to expose the conductive core. The solder paste dots are in contact with the electrodes of the back contact solar cell and are in contact with the conductive core through the openings.

2. The solar cell string according to claim 1, characterized in that, The surfaces of the conductive core, other than the surface in contact with the solder paste, are electrically insulated and protected by the organic solderability protective layer.

3. A solar cell string, characterized in that, The system includes a wiring component and at least two back-contact solar cells, the wiring component connecting the back-contact solar cells in series, the wiring component including a conductive core and an electrically insulating organic solderable protective layer covering the surface of the conductive core, wherein... The back of the back contact solar cell is provided with a plurality of solder paste dots distributed on the back side. The solder paste dots are in direct contact with the electrodes of the back contact solar cell and a local surface of the conductive core. Except for the local surface of the conductive core that is in contact with the solder paste dots, the other surfaces of the conductive core are covered with the organic solderability protective layer.

4. The solar cell string according to any one of claims 1-3, characterized in that, The solder paste point is a cured solder paste point, and the solder paste point contains flux.

5. The solar cell string according to any one of claims 1-3, characterized in that, The organic solderable protective layer is a triazine indene film or an imidazole organic crystalline alkali film.

6. The solar cell string according to any one of claims 1-3, characterized in that, The conductive core is a bare wire.

7. The solar cell string according to claim 6, characterized in that, The conductive core is made of bare copper wire, bare aluminum wire, bare nickel wire, or bare silver wire.

8. The solar cell string according to any one of claims 1-3, characterized in that, The thickness of the organic solderable protective layer in the wiring component is 0.2-10 μm.

9. The solar cell string according to any one of claims 1-3, characterized in that, The maximum width of the conductive inner core is 0.18-0.8 mm.

10. The solar cell string according to any one of claims 1-3, characterized in that, The cross-section of the conductive inner core is circular, rectangular, or triangular.

11. The solar cell string according to any one of claims 1-3, characterized in that, The resistivity of the organic solderable protective layer is 10. 7 -10 12 Ω·m.

12. The solar cell string according to any one of claims 1-3, characterized in that, The back-contact solar cell includes a silicon substrate, a first semiconductor region and a second semiconductor region formed on the back side of the silicon substrate, a first electrode in contact with the first semiconductor region, and a second electrode in contact with the second semiconductor region. The wiring component connects the first electrode of one back-contact battery in series with the second electrode of another back-contact battery.

13. The solar cell string according to claim 12, characterized in that, The first electrode includes a first bus electrode extending along a first direction and a first finger electrode extending along a second direction. The second electrode includes a second bus electrode extending along the first direction and a second finger electrode extending along the second direction. The first direction intersects the second direction. The first bus electrode and the second bus electrode are alternately arranged in the second direction, and the first finger electrode and the second finger electrode are alternately arranged in the first direction. The first electrode and the second electrode are spaced apart from each other. The first bus electrode and the second bus electrode are respectively provided with a plurality of pads, and the solder paste dots are connected to the pads.

14. The solar cell string according to claim 13, characterized in that, Each of the aforementioned bus electrodes has 5-10 pads spaced apart.

15. The solar cell string according to claim 12, characterized in that, The first semiconductor region includes a first dielectric layer formed on the surface of the silicon substrate and a first doped silicon layer formed on the surface of the first dielectric layer; the second semiconductor region includes a second dielectric layer formed on the surface of the silicon substrate and a second doped silicon layer formed on the surface of the second dielectric layer; the first doped silicon layer and the second doped silicon layer have opposite conductivity types.

16. The solar cell string according to claim 15, characterized in that, The first and second dielectric layers are tunneling oxide layers, and the first and second doped silicon layers are doped polysilicon layers; or, The first dielectric layer and the second dielectric layer are intrinsic amorphous silicon layers, and the first doped silicon layer and the second doped silicon layer are doped amorphous silicon layers; or, The first dielectric layer is a tunneling oxide layer, the first doped silicon layer is a doped polycrystalline silicon layer, the second dielectric layer is an intrinsic amorphous silicon layer, and the second doped silicon layer is a doped amorphous silicon layer.

17. A solar cell module, characterized in that, Includes the solar cell string as described in any one of claims 1-3.

18. A method for preparing solar cell strings, characterized in that, A wiring component with a complete organic solderable protective layer on its surface is brought into contact with solder paste dots on the electrodes of a back-contact solar cell and heated, causing the portion of the organic solderable protective layer in contact with the solder paste dots to melt, while the remaining portion not in contact with the solder paste dots is still covered with an electrically insulating organic solderable protective layer.

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