Solar cell manufacturing method and shingled module

Abstract

The present invention relates to a method for manufacturing solar cell wafers, solar cell wafers, and shingled modules. In the method of the present invention, the step of scribing large-sized cell wafers includes the following steps: laser scribing and ablating the large-sized cell wafers at the junction positions between each pair of adjacent cell units on the first side surface of the large-sized cell wafers. In the present invention, laser scribing and ablating treatments are performed at each junction position on the side surface of the large-sized cell wafers to introduce microcracks / stress regions. This can avoid the formation of impurity particles on the top / back surfaces of the large-sized cell wafers caused by front / back laser scribing and fracturing, and can improve the performance and production yield of the manufactured solar cell wafers. Moreover, the method provided by the present invention further includes a method of achieving non-destructive fracturing by applying a refrigerant gas to the surface of a heated silicon wafer, which can perform fracturing without introducing mechanical stress, avoid mechanical damage, and further improve the electrical performance and yield of the cell wafer during unloading.

Description

Technical Field

[0001] The present invention relates to the field of energy, and particularly to a manufacturing method of a solar cell, a solar cell, and a shingled module. Background Art

[0002] With the accelerating consumption rate of conventional fossil energy such as coal, oil, and natural gas globally, the ecological environment is deteriorating continuously. Especially, greenhouse gas emissions have led to increasingly severe global climate change, and the sustainable development of human society has been seriously threatened. Countries around the world have successively formulated their respective energy development strategies to address the limited nature of conventional fossil energy resources and the environmental problems brought about by their exploitation and utilization. Solar energy has become one of the most important renewable energy sources due to its characteristics of reliability, safety, universality, long life, environmental protection, and abundant resources, and is expected to become the main pillar of future global power supply.

[0003] In the process of a new round of energy transformation, China's photovoltaic industry has grown into a strategic emerging industry with international competitive advantages. However, the development of the photovoltaic industry still faces many problems and challenges. Conversion efficiency and reliability are the biggest technical obstacles restricting the development of the photovoltaic industry, while cost control and scale-up pose economic constraints. As the core component of photovoltaic power generation, it is an inevitable trend to improve the conversion efficiency of photovoltaic modules and develop high-efficiency modules. Currently, various high-efficiency modules have emerged in the market, such as shingled, half-cell, multi-busbar, and bifacial modules. With the increasingly wide application scenarios and regions of photovoltaic modules, the requirements for their reliability are getting higher and higher. Especially in some areas with frequent severe or extreme weather, high-efficiency and high-reliability photovoltaic modules are needed.

[0004] When manufacturing solar cells and shingled modules, it is necessary to cleave large sheets of cells into solar cells of the required size. In the current production process, laser radiation is usually used for cleaving. The laser spots irradiate the top surface and the bottom surface of the large sheet of cells. The material of the large sheet of cells strongly absorbs the laser power and is melted and ablated after sufficient heat accumulation. Finally, the large sheet of cells is cleaved by mechanical external force to form solar cells of the required size. However, this method has the following disadvantages in actual processes: For example, when the laser spots irradiate the top surface or the bottom surface of the large sheet of cells, the metal paste and various dielectric layer materials on the top surface and / or the bottom surface form particulate impurities during the melting process, resulting in a large amount of impurity contamination at the cleavage edge, seriously affecting the performance and production yield of the manufactured solar cells.

[0005] In view of this, many researchers have tried to improve the above-mentioned technologies. For example, some existing technologies generate photoinduced damage near the focal point of the laser within the processing object to form stress points, constituting an internal stress layer, generating a single continuous microcrack region in the bulk material according to the focal point of each laser pulse, and then processing by introducing mechanical force to cause the bulk material to expand along the crack and separate along the desired separation line. However, such technologies do not completely eliminate the contamination caused by the melting of surface impurities and do not fundamentally solve the technical problem of lossless splitting.

[0006] Therefore, it is necessary to provide a method for manufacturing solar cell wafers, large wafer pieces, solar cell wafers, and shingled modules to solve the above problems. Summary of the Invention

[0007] The object of the present invention is to provide a method for manufacturing solar cell wafers, large wafer pieces, solar cell wafers, and shingled modules. In the method given by the present invention, laser dot ablation treatment is performed at each intersection position on the side surface (instead of the top surface and the bottom surface) of the large wafer piece to introduce microcracks / stress regions. This can avoid forming particulate impurities on the top surface of the large wafer piece and can improve the performance and production yield of the manufactured solar cell wafers.

[0008] Moreover, the method provided by the present invention further includes achieving lossless splitting by applying a refrigerant gas on the surface of the heated silicon wafer, which can split without introducing mechanical stress and avoid mechanical damage.

[0009] According to one aspect of the present invention, there is provided a method for manufacturing solar cell wafers. The method includes a splitting step of splitting a large wafer piece. The large wafer piece includes a plurality of cell units arranged in a first direction, and the large wafer piece has a top surface, a bottom surface, and two first side surfaces and two second side surfaces located between the top surface and the bottom surface. The two first side surfaces are surfaces defined by the first direction and the thickness direction of the large wafer piece, and the two second side surfaces are surfaces defined by the thickness direction and a second direction. The second direction is perpendicular to both the thickness direction and the first direction at the same time.

[0010] The splitting step includes the following steps:

[0011] Laser dot ablating the large wafer piece at the intersection position between each pair of adjacent cell units on the two first side surfaces of the large wafer piece;

[0012] An intermediate processing step; and

[0013] Each pair of adjacent cell units of the large cell sheet are separated from each other, and each cell unit is formed as one solar cell sheet.

[0014] In one embodiment, the intermediate processing step includes: the step of heating the large cell sheet and the step of applying a refrigerant gas to the surface of the large cell sheet.

[0015] In one embodiment, the method includes the step of presetting laser target points on the two first side surfaces of the large cell sheet, and the step of laser dot ablation includes: aiming a laser emitter at the laser target points and emitting a laser.

[0016] In one embodiment, the steps of the method for presetting laser target points include: setting a group of the laser target points at each of the junction positions on each of the first side surfaces, arranging the respective laser target points in each group along the thickness direction of the large cell sheet, and setting the respective laser target points on the two first side surfaces to be at the same height in terms of thickness.

[0017] In one embodiment, each group of the laser target points are arranged at equal intervals in sequence, and the distance between adjacent laser target points is 15 - 50 μm.

[0018] In one embodiment, the method includes: configuring the large cell sheet to have a thickness of 100 - 300 μm, and the method further includes: adjusting the parameters of the laser emitter and its distance from the large cell sheet so that the diameter of the laser beam spot formed by the laser on the large cell sheet is 15 - 35 μm.

[0019] In one embodiment, adjust the parameters of the laser emitter and its distance from the large cell sheet so that the distance of the laser beam spot formed by the laser on the large cell sheet from the top surface and from the bottom surface in the thickness direction is greater than 15 μm.

[0020] In one embodiment, the step of heating the large cell sheet includes: heating the large cell sheet to 30 - 100 °C.

[0021] In one embodiment, the step of introducing the refrigerant gas includes: applying the refrigerant gas at the junction positions on the top surface and the bottom surface of the large cell sheet, and allowing the refrigerant gas to diffuse along the junction line at the junction positions of the cell units.

[0022] In one embodiment, the scribing step does not include the operation of scribing the large cell sheet using mechanical stress.

[0023] According to another aspect of the present invention, there is provided a large wafer of solar cells for scribing to form solar cells. The large wafer of solar cells includes a plurality of solar cell units arranged in a first direction, and the large wafer of solar cells has a top surface, a bottom surface, two first side surfaces located between the top surface and the bottom surface, and two second side surfaces. The two first side surfaces are surfaces defined by the first direction and the thickness direction of the large wafer of solar cells, and the two second side surfaces are surfaces defined by the thickness direction and a direction that is perpendicular to both the thickness direction and a second direction. The second direction is perpendicular to both the first direction and the thickness direction.

[0024] At the junction positions of adjacent solar cell units on the two first side surfaces, laser target points are preset. The laser target points are configured to be aimed at by a laser emitter as laser emission targets, so that the two first side surfaces of the large wafer of solar cells are ablated by laser after the laser emitter emits laser.

[0025] In one embodiment, a set of laser target points is provided at each junction position of each first side surface, and the laser target points in each set are arranged along the thickness direction of the large wafer of solar cells.

[0026] In one embodiment, the laser target points on the two first side surfaces are arranged at the same height in terms of thickness.

[0027] In one embodiment, the laser target points in each set are arranged at equal intervals in sequence, and the distance between adjacent laser target points is 15 - 50 μm.

[0028] In one embodiment, the thickness of the large wafer of solar cells is 100 - 300 μm, and the size of the laser target points is consistent with the size of the laser beam spots that the laser can actually form on the large wafer of solar cells. The diameter of the laser target points is 15 - 35 μm.

[0029] In one embodiment, the distances between the laser target points and the top surface, and between the laser target points and the bottom surface in the thickness direction are both greater than 15 μm.

[0030] In one embodiment, each set of laser target points has 3 - 7.

[0031] In one embodiment, the large wafer of solar cells is a single crystal or quasi-single crystal solar cell wafer.

[0032] According to still another aspect of the present invention, there is provided a solar cell formed by scribing a large wafer of solar cells according to any one of the above solutions.

[0033] According to another aspect of the present invention, there is provided a shingled module, including a battery string, which is formed by arranging a plurality of solar cells according to the above solution in a shingled manner along a direction consistent with the first direction.

[0034] According to the present invention, there are provided a method for manufacturing a solar cell, a large piece of cell, a solar cell, and a shingled module. In the method provided by the present invention, laser dot ablation treatment is performed at each junction position on the side surface of the large piece of cell to introduce microcracks / stress regions, and then a refrigerant gas is applied at each junction position on the top surface and the bottom surface of the large piece of cell for microcrack propagation treatment. This can avoid the formation of particulate impurities on the top surface of the large piece of cell, improve the performance and production yield of the manufactured solar cells. Moreover, the method provided by the present invention includes achieving crack-free splitting by applying a refrigerant gas on the surface of the heated silicon wafer, which can split the wafer without introducing mechanical stress and avoid mechanical damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] To better understand the above and other objects, features, advantages, and functions of the present invention, reference may be made to the preferred embodiments shown in the accompanying drawings. The same reference numerals in the drawings refer to the same components. Those skilled in the art should understand that the drawings are intended to schematically illustrate the preferred embodiments of the present invention and have no restrictive effect on the scope of the present invention. The components in the drawings are not drawn to scale.

[0036] Figure 1 A three-dimensional schematic diagram of a large piece of cell according to a preferred embodiment of the present invention;

[0037] Figure 2 For Figure 1 a partial enlarged schematic diagram of part A in DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] Now referring to the accompanying drawings, the detailed embodiments of the present invention will be described in detail. What is described here is only the preferred embodiments of the present invention. Those skilled in the art can think of other ways to implement the present invention based on the preferred embodiments, and such other ways also fall within the scope of the present invention.

[0039] The present invention provides a method for manufacturing a solar cell, a large piece of cell, a solar cell, and a shingled module. The following refers to Figure 1 and Figure 2 to describe a preferred embodiment according to the present invention.

[0040] It should be noted first that the "first direction" mentioned herein can be understood as the direction extending along the X-axis in Figure 1 ; the "second direction" mentioned herein can be understood as the direction extending alongFigure 1 the direction in which the Y-axis extends; the "thickness direction of the large wafer of the cell" mentioned in this article can be understood as the direction extending along the Figure 1 Z-axis shown in

[0041] Figure 1 FIG. shows a large wafer 100 of a cell in a preferred embodiment. The large wafer 100 of the cell can be used to manufacture solar cells. For example, the large wafer 100 of the cell can be used to manufacture single-crystalline solar cells. The large wafer 100 of the cell may include a substrate wafer and grid lines provided on the top surface 101 and / or the bottom surface of the substrate wafer. The substrate wafer may be, for example, one of an alumina monolithic structure, a silicon monolithic structure, a gallium arsenide monolithic structure, and a gallium nitride monolithic structure.

[0042] The large wafer 100 of the cell in this embodiment includes a plurality of cell units 1 arranged in a first direction. After the large wafer 100 of the cell is cleaved, each cell unit 1 will be formed into a solar cell. The large wafer 100 of the cell is a cuboid structure. The height of the cuboid (i.e., the thickness of the large wafer 100 of the cell) is much smaller than the length and width of the cuboid. The six surfaces of the cuboid structure are the top surface 101, the bottom surface, and four side surfaces. These four side surfaces include two opposite first side surfaces 103 and two opposite second side surfaces 104. Among them, the first side surface 103 is the surface defined by the first direction and the thickness direction of the large wafer 100 of the cell, and the second side surface 104 is the surface defined by the second direction and the thickness direction of the large wafer 100 of the cell. In this embodiment, the thickness of the large wafer 100 of the cell (shown in Figure 2 ) is 100-300 μm.

[0043] The method for manufacturing a solar cell includes the step of cleaving the large wafer 100 of the cell as shown in Figure 1 . Among them, the cleaving step includes: laser dot ablation of the large wafer 100 at the junction position 2 between each pair of adjacent cell units 1 on the first side surface 103 of the large wafer 100.

[0044] Preferably, laser target points 21 are preset at the junction positions 2 of adjacent cell units 1 on the first side surface 103 of the large cell sheet 100, and the laser emitter can aim at the laser target points 21 and emit laser light. When using the laser emitter to aim at the laser target points 21 and apply a laser beam to the large cell sheet 100, the parameters of the laser emitter and its distance from the large cell sheet 100 can be adjusted so that the spot formed by the laser beam emitted by the laser emitter on the large cell sheet 100 has the same size as the laser target points 21. That is to say, the size and position of the laser target points 21 mentioned in this embodiment are actually also the size and position of the spot formed by the laser beam on the first side surface 103 of the large cell sheet 100.

[0045] There are multiple groups of laser target points 21, and a group of laser target points 21 is provided at each junction position 2 of each first side surface 103.

[0046] Figure 2 An enlarged schematic diagram of one group of laser target points 21 is shown. As can be seen from Figure 2 it, the multiple laser target points 21 in each group are arranged along the thickness direction of the large cell sheet 100. Preferably, the laser target points 21 in each group are arranged at equal intervals in sequence. Preferably, the respective laser target points on the two first side surfaces are arranged at the same height in the thickness direction. Preferably, a group of laser target points 21 can be 3 - 7.

[0047] Continue to refer to Figure 2 , the diameter D1 of each laser target point 21 is approximately 15 - 35 μm, and the distance D2 between adjacent laser target points 21 is 15 - 50 μm. Preferably, the distance between each laser target point 21 and the top surface 101 and the distance between it and the bottom surface in the thickness direction are both greater than 15 μm. For example, the distance D3 between the top - most laser target point 21 and the top surface of the large cell sheet is greater than 15 μm, and the distance D4 between the bottom - most laser target point 21 and the bottom surface of the large cell sheet is also greater than 15 μm. The distance D3 between the top - most laser target point 21 and the top surface of the large cell sheet and the distance D4 between the bottom - most laser target point 21 and the bottom surface of the large cell sheet can be equal or unequal.

[0048] After the laser beam ablates the large cell sheet 100 by punching, micro - cracks and micro - stresses will spread around with the ablation point as the center. Setting the distance D2 between adjacent laser target points 21 to 15 - 50 μm is conducive to the expansion of micro - cracks and micro - stresses in the preset direction, thereby facilitating the dissociation of the cell units in the large cell sheet along the interface.

[0049] Using laser ablation on the side surface (instead of the top surface 101 and the bottom surface) of the large wafer 100 of the solar cell can avoid the appearance of particulate impurities near the intersection area where the junction position 2 of the solar cell units 1 intersects with the bottom surface and the top surface, thereby improving the electrical performance and production yield of the manufactured solar cells.

[0050] In the step of scribing the large wafer 100 of the solar cell, in addition to the above step of applying laser to make the large wafer 100 of the solar cell be dot-ablated, it further includes an intermediate treatment step. The intermediate treatment step can include, for example, the step of heating the large wafer 100 of the solar cell and the step of introducing a refrigerant gas into the large wafer 100 of the solar cell.

[0051] Specifically, the step of heating the large wafer 100 of the solar cell can include: heating the large wafer 100 of the solar cell to 30 - 100 °C.

[0052] And the step of introducing the refrigerant gas after the heating step includes: applying the refrigerant gas at the junction position on the top surface 101 and the bottom surface of the large wafer 100 of the solar cell, and preferably making the refrigerant gas diffuse along the second direction, that is, along the junction line between the solar cell units 1.

[0053] Applying the refrigerant gas to the heated large wafer 100 of the solar cell can cause the hot large wafer 100 of the solar cell to further expand the microcracks and microstresses generated by the laser ablation under the shrinking action of the refrigerant gas, so that the large wafer 100 of the solar cell can be scribed along the junction line between the solar cell units 1 at the junction position 2 of the solar cell units 1, and each solar cell unit 1 is formed into a solar cell.

[0054] Preferably, the operating device for applying the refrigerant gas to the top surface and the bottom surface of the junction position 2 of any pair of adjacent solar cell units 1 can operate independently of the operating device for applying the refrigerant gas to the junction position 2 of other adjacent solar cell units 1. That is to say, the operating device for applying the refrigerant gas to the junction position 2 of any pair of adjacent solar cell units 1 can be independently controlled.

[0055] After the large wafer 100 of the solar cell undergoes the alternating action of heating and the refrigerant gas, after the connection part of the adjacent solar cell units 1 continuously expands the microcracks and microstresses, the microcracks will expand to near the top surface and the bottom surface of the solar cell. At this time, the large wafer 100 of the solar cell can be split along the junction line (extending along the second direction) at each of its junction positions 2 without additional mechanical stress, thereby completing the scribing step.

[0056] In addition to the scribing step, the method for manufacturing solar cells mentioned in the present invention further includes other steps, for example, it can further include the step of manufacturing the large wafer 100 of the solar cell and the step of treating the large wafer 100 of the solar cell before scribing.

[0057] In the solution provided by the present invention, laser dot ablation treatment is carried out at each intersection position on the side surface (instead of the top surface and the bottom surface) of the large piece of solar cell to introduce microcracks / stress regions. This can avoid forming particulate impurities on the top surface of the large piece of solar cell, and can improve the performance and production yield of the manufactured solar cells. Moreover, after the dot ablation, a refrigerant gas is applied at each intersection position on the top surface and the bottom surface of the large piece of solar cell for microcrack propagation treatment to achieve cell separation. Therefore, the method provided by the present invention can also achieve cell separation without introducing mechanical stress, but by using the methods of heating and introducing refrigerant gas to achieve non-destructive cell separation.

[0058] The above description of various embodiments of the present invention is provided to a person of ordinary skill in the relevant art for the purpose of description. It is not intended to exclude or limit the present invention to a single disclosed embodiment. As described above, a person of ordinary skill in the art taught above will understand various alternatives and modifications of the present invention. Therefore, although some alternative embodiments are specifically described, a person of ordinary skill in the art will understand or relatively easily develop other embodiments. The present invention is intended to include all alternatives, modifications and variations of the present invention described herein, as well as other embodiments that fall within the spirit and scope of the present invention described above.

[0059] Reference numerals:

[0060] Large piece of solar cell 100

[0061] Top surface of the large piece of solar cell 101

[0062] First side surface of the large piece of solar cell 103

[0063] Second side surface of the large piece of solar cell 104

[0064] Solar cell unit 1

[0065] Intersection position between solar cell units 2

[0066] Laser target point 21.

Claims

1. A method for manufacturing solar cell wafers, the method including a scribing step of scribing a large solar cell wafer, the large solar cell wafer including a plurality of cell units arranged in a first direction, and the large solar cell wafer having a top surface, a bottom surface, and two first side surfaces and two second side surfaces located between the top surface and the bottom surface, the two first side surfaces being surfaces defined by the first direction and the thickness direction of the large solar cell wafer, and the two second side surfaces being surfaces defined by the thickness direction and a second direction, the second direction being perpendicular to both the thickness direction and the first direction simultaneously. It is characterized in that The scribing step includes the following steps: Laser dot ablation of the large solar cell wafer at the junction positions between each pair of adjacent cell units on the two first side surfaces of the large solar cell wafer; An intermediate processing step, the intermediate processing step including: a step of heating the large solar cell wafer and a step of applying a refrigerant gas to the junction positions on the surface of the large solar cell wafer; And Each pair of adjacent cell units of the large solar cell wafer are separated from each other, and each cell unit is formed into a solar cell wafer.

2. The method according to claim 1, wherein The method includes a step of presetting laser target points on the two first side surfaces of the large solar cell wafer, and the laser dot ablation step includes: aiming a laser emitter at the laser target points and emitting a laser.

3. The method according to claim 2, characterized in that, The steps of the method for presetting laser target points include: arranging a set of laser target points at each junction position on each of the two first side surfaces, such that each laser target point in each set is arranged along the thickness direction of the large solar cell wafer, and the laser target points on the two first side surfaces are arranged at the same height in terms of thickness.

4. The method according to claim 3, wherein Each set of laser target points are arranged at equal intervals in sequence, and the distance between adjacent laser target points is 15 - 50 μm.

5. The method according to claim 3, wherein The method includes: configuring the large solar cell wafer to have a thickness of 100 - 300 μm, and the method further includes: adjusting the parameters of the laser emitter and its distance from the large solar cell wafer, such that the diameter of the laser beam spot formed by the laser on the large solar cell wafer is 15 - 35 μm.

6. The method according to claim 3, characterized in that, Adjusting the parameters of the laser emitter and its distance from the large solar cell wafer, such that the distance between the laser beam spot formed by the laser on the large solar cell wafer and the top surface and the distance from the bottom surface in the thickness direction are both greater than 15 μm.

7. The method according to claim 1, characterized in that, The step of heating the large solar cell wafer includes: heating the large solar cell wafer to 30 - 100 °C.

8. The method according to claim 1, wherein The step of introducing the refrigerant gas includes: applying the refrigerant gas at the junction positions on the top surface and the bottom surface of the large solar cell wafer, and causing the refrigerant gas to diffuse along the junction line at the junction positions of the cell units.

9. The method according to claim 1, characterized in that The scribing step does not include an operation of scribing the large solar cell wafer using mechanical stress.

10. A large wafer of solar cells, which is used for scribing to form solar cells. The large wafer of solar cells includes a plurality of cell units arranged in a first direction, and the large wafer of solar cells has a top surface, a bottom surface, two first side surfaces located between the top surface and the bottom surface, and two second side surfaces. The two first side surfaces are surfaces defined by the first direction and the thickness direction of the large wafer of solar cells, and the two second side surfaces are surfaces defined by the thickness direction and a direction perpendicular to both the thickness direction and a second direction. The second direction is perpendicular to both the first direction and the thickness direction. Characterized in that, At the junction positions of adjacent cell units on the two first side surfaces, laser target points are preset. The laser target points are configured to be aimed at by a laser emitter as the laser emission targets, so that after the laser emitter emits laser, the two first side surfaces of the large wafer of solar cells are ablated by the laser. Wherein, the large wafer of solar cells can be scribed to form solar cells through the following steps: laser ablation at the laser target points on the two first side surfaces; heating the large wafer of solar cells; applying a refrigerant gas to the junction positions on the surface of the large wafer of solar cells; and separating each pair of adjacent cell units of the large wafer of solar cells.

11. The large battery chip according to claim 10, characterized in that, A set of laser target points is provided at each junction position of each first side surface. Each laser target point in each set is arranged along the thickness direction of the large wafer of solar cells, and the laser target points on the two first side surfaces are arranged at the same height in the thickness direction.

12. The large battery cell according to claim 11, characterized in that, The laser target points in each set are arranged at equal intervals in sequence, and the distance between adjacent laser target points is 15 - 50 μm.

13. The large battery chip according to claim 11, wherein The thickness of the large wafer of solar cells is 100 - 300 μm, and the size of the laser target points is consistent with the size of the laser beam spots that the laser can actually form on the large wafer of solar cells. The diameter of the laser target points is 15 - 35 μm.

14. The large battery chip according to claim 11, wherein The distance between the laser target points and the top surface, as well as the distance between the laser target points and the bottom surface, in the thickness direction are both greater than 15 μm.

15. The large piece of battery cell according to claim 11, wherein Each set of laser target points is 3 - 7 in number.

16. The large battery chip according to any one of claims 11-15, characterized in that The large wafer of solar cells is a single-crystal or quasi-single-crystal solar cell wafer.

17. A solar cell formed by scribing a large wafer of solar cells according to any one of claims 10 - 16.

18. A shingled module, including a cell string, which is formed by arranging a plurality of solar cells according to claim 17 in a shingled manner along a direction consistent with the first direction.

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