Crystalline silicon solar cell preparation method and solar cell
By disconnecting the positive main gate and the negative main gate at the edge of the silicon wafer of the crystalline silicon solar cell and forming a reserved channel, the problem of current and efficiency loss in the back contact battery is solved, and higher battery efficiency and lower production costs are achieved.
Patent Information
- Application Number
- CN202411626803.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-14
- Publication Date
- 2025-03-11
AI Technical Summary
In the back contact battery, the existing crystal silicon solar cells have a loss of current and efficiency due to the interconnection of positive and negative electrodes, which reduces the efficiency of the battery.
By connecting the positive main gate and the negative main gate at the edge of the silicon wafer by disconnecting each other, and disconnecting the negative main gate to form a reserved channel, so that the positive and negative current can be completely exported.
Reduces current loss, improves battery efficiency of back contact batteries, and reduces production costs.
Smart Images
Figure CN119604060A_ABST
Abstract
Description
Technical Field
[0001] The present invention discloses the technical field of solar cell production, and in particular relates to a method for preparing a crystalline silicon solar cell and a solar cell. Background Art
[0002] Crystalline silicon solar cells are the most common type of solar cells. They use the photoelectric effect of semiconductor materials such as silicon (Si) to convert sunlight into electrical energy. They are widely used in rooftops, solar power stations, and portable electronic devices.
[0003] The main design method of mass-produced crystalline silicon solar cell electrodes is: both the light-receiving side and the backlight side have positive and negative silver electrodes, and relatively few electrodes are designed only on the backlight side. However, in the positive and negative electrodes designed on the backlight side, since the positive and negative electrodes are connected to each other, the positive and negative currents can be extracted, which easily leads to current and efficiency losses, thereby reducing the battery efficiency of the back contact battery. Summary of the invention
[0004] To solve the above problems, the present disclosure provides a method for preparing a crystalline silicon solar cell and a solar cell, which achieves high-temperature sintering and prints the positive main grid and the negative main grid at one time, and connects them in a mutually disconnected manner at the edge of the silicon wafer to ensure that the positive and negative currents can be fully extracted, reduce current losses, and improve the battery efficiency of the back-contact battery.
[0005] A first aspect of the present disclosure provides a method for preparing a crystalline silicon solar cell, comprising:
[0006] A substrate is provided; a positive electrode fine grid and a negative electrode fine grid are formed on one side of the substrate; a positive electrode main grid is formed on the substrate based on the positive electrode fine grid, and the positive electrode main grid is connected to the positive electrode fine grid; a negative electrode main grid is formed on the substrate based on the negative electrode fine grid, and the negative electrode main grid is connected to the negative electrode fine grid, and the negative electrode main grid and the positive electrode main grid are located on the same side of the substrate; a reserved channel is formed by disconnecting the negative electrode main grid, and the reserved channel is used for connecting the positive electrode fine grid to the positive electrode main grid.
[0007] It is arranged in this way so that after the positive electrode fine grid forms a positive electrode on the substrate and the negative electrode fine grid forms a negative electrode on the substrate, the positive electrode is connected to the positive electrode main grid through the reserved channel, so that the positive current can be output through the positive electrode main grid, so that the positive and negative electrodes can be disconnected on the substrate through the reserved channel, and the positive and negative electrodes are connected to the main grid when disconnected, so that the positive and negative electrode currents can be exported, reducing current loss, thereby improving the battery efficiency of the back contact battery.
[0008] In some embodiments, forming the positive electrode fine gate and the negative electrode fine gate based on one side of the substrate includes: etching the positive electrode fine gate and the negative electrode fine gate regions on the substrate along the thickness direction of the substrate, and the etching depths of the positive electrode fine gate region and the negative electrode fine gate region are different.
[0009] Such an arrangement enables the positive electrode formed by the positive electrode fine grid and the negative electrode formed by the negative electrode fine grid to have different depths on the substrate, which helps to completely isolate the positive electrode from the negative electrode, thereby reducing leakage.
[0010] In some embodiments, the disconnection on the negative electrode main grid to form a reserved channel, wherein the reserved channel is used for connecting the positive electrode fine grid to the positive electrode main grid, comprises: forming an insulating layer at the reserved channel formed by the disconnection of the negative electrode main grid.
[0011] This arrangement is used to insulate and isolate the disconnected position of the negative electrode main grid, thereby preventing the positive electrode main grid from being connected to the negative electrode main grid through the reserved channel, and further strengthening the isolation between the positive and negative electrodes.
[0012] In some embodiments, the method includes: a first printing process to form the positive electrode fine grid; a second printing process to form the negative electrode fine grid; and a third printing process to form the positive electrode main grid and the negative electrode main grid.
[0013] With this arrangement, the printing of the positive electrode fine grid, the negative electrode fine grid, the positive electrode main grid and the negative electrode main grid is completed through three processes, which reduces the printing process sequence, improves printing efficiency and reduces production costs.
[0014] In some embodiments, the material used to print the positive electrode fine grid and the negative electrode fine grid is a burn-through paste, and the material used to print the positive electrode main grid and the negative electrode main grid is a non-burn-through paste.
[0015] The positive and negative electrodes are configured in this way so that they can penetrate the metal layer at high temperature to form a fine conductive path, which is suitable for high-precision circuit applications; rather than the main grid that burns through the slurry, it is to protect the underlying metal to prevent excessive corrosion or burn-through.
[0016] In some embodiments, the line width of the positive electrode busbar and the negative electrode busbar ranges from 50 μm to 80 μm.
[0017] With this arrangement, the current loss is large due to the long current line design. By using the above data to thicken the positive and negative main grids, the current loss can be reduced.
[0018] In some embodiments, the line width of the positive electrode fine grid and the negative electrode fine grid is in the range of 13 μm-16 μm.
[0019] Such arrangement enables the positive electrode fine grid and the negative electrode fine grid line width to be narrower, so as to further reduce the cost and increase the efficiency.
[0020] A second aspect of the present disclosure provides a crystalline silicon solar cell, the cell comprising:
[0021] A substrate; a positive electrode fine grid, located on one side of the substrate; a negative electrode fine grid, located on the same side of the substrate as the positive electrode fine grid, and the negative electrode fine grid and the positive electrode fine grid are staggered; a positive electrode main grid and a negative electrode main grid, a positive electrode main grid is formed on the substrate based on the positive electrode fine grid, and the positive electrode main grid is connected to the positive electrode fine grid; a negative electrode main grid is formed on the substrate based on the negative electrode fine grid, and the negative electrode main grid is connected to the negative electrode fine grid, and the negative electrode main grid and the positive electrode main grid are located on the same side of the substrate; a reserved channel is formed by disconnecting the negative electrode main grid, and the reserved channel is used for connecting the positive electrode fine grid to the positive electrode main grid.
[0022] It is arranged in this way so that the positive electrode fine grid can be connected to the positive electrode main grid through the reserved channel of the negative electrode main grid, so that the offset positive electrode fine grid and negative electrode fine grid are also separated when connected to the main grid, which helps to connect the positive and negative electrodes with the main grid when they are disconnected, so that the positive and negative electrode currents can be extracted, reducing current loss.
[0023] In some embodiments, the positive main grid includes a first positive main grid and a second positive main grid located on the substrate, and the second positive main grid is close to the edge of the substrate; the negative main grid includes a first negative main grid and a second negative main grid located on the substrate, and the second negative main grid is close to the edge of the substrate, and the second negative main grid is disconnected to form the reserved channel.
[0024] This arrangement makes it easy to disconnect the negative main grid near the edge of the substrate, and guide the current at the edge of the substrate to the positive main grid through the reserved channel, which helps the positive main grid collect the current at the edge of the substrate.
[0025] In some embodiments, the positive first main grid, the negative first main grid and the negative second main grid are arranged parallel to each other, the positive second main grid is perpendicular to the positive first main grid, and a plurality of reserved channels are arranged at intervals along the extension direction of the negative second main grid, and each of the positive second main grids passes through the reserved channel and is connected to the positive fine grid through the positive first main grid.
[0026] Such an arrangement enables the negative electrode main grid to be disconnected at the edge of the substrate, so that the positive electrode main grid can further collect the current at the edge of the substrate.
[0027] Compared with the prior art, the present invention has the following advantages:
[0028] 1. The positive and negative main grids are printed at one time, and the edge collection method is disconnected from each other at the edge of the silicon wafer. The positive and negative currents can be completely extracted, reducing the loss of battery current and efficiency.
[0029] 2. The screen graphic design can simplify the printing process, realize three-step printing process, reduce production costs, and is suitable for back contact batteries.
[0030] 3. It can match high temperature sintering, the main grid has large tensile force and strong reliability.
[0031] 4. Laser window opening technology is used to isolate the positive and negative electrodes to reduce leakage of finished batteries.
[0032] Other features and advantages of the present disclosure will be described in the following description, and partly become apparent from the description, or be understood by implementing the present disclosure. The purpose and other advantages of the present disclosure can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0034] Figure 1 It is a schematic diagram of a process for preparing a crystalline silicon solar cell provided by an embodiment of the present disclosure;
[0035] Figure 2 It is a schematic diagram of a complete graphic printing of a crystalline silicon solar cell electrode provided by an embodiment of the present disclosure;
[0036] Figure 3 It is a schematic diagram of a battery printing positive electrode screen provided by an embodiment of the present disclosure;
[0037] Figure 4 is a schematic diagram of a battery printed negative electrode screen provided by an embodiment of the present disclosure;
[0038] Figure 5 It is a schematic diagram of a printed positive electrode main grid and a negative electrode main grid of a battery provided by an embodiment of the present disclosure;
[0039] Figure 6 It is an enlarged schematic diagram of the negative electrode main grid being disconnected to form a reserved channel provided by an embodiment of the present disclosure. DETAILED DESCRIPTION
[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.
[0041] The following is a brief introduction to some concepts that may be involved in the embodiments of the present disclosure.
[0042] Among crystalline silicon solar cells, back-contact cells are a special solar cell structure that concentrates both the positive and negative electrodes on the same side of the cell. In back-contact cells, the positive and negative grid lines do not directly contact the surface of the silicon wafer, but are formed on the back of the cell by diffusion or deposition. The function of these grid lines is to form a current collection path inside the cell to guide and control the flow of current to the edge of the cell. Both the positive and negative main grid lines are large-area metal lines that are connected to each small unit in the cell array. The positive main grid line is responsible for collecting electrons generated from the P-type layer, while the negative main grid line is responsible for collecting holes generated from the N-type layer, aggregating these local currents and transmitting them to the external circuit to achieve the overall power generation function.
[0043] like Figure 1 As shown, Figure 1 The present invention provides a method for preparing a crystalline silicon solar cell, which comprises the following steps:
[0044] S100 , providing a substrate.
[0045] In this embodiment, the surface of the silicon wafer of the substrate is first polished and cleaned to remove line marks, metal impurities, etc. on the surface of the silicon wafer. The material of the substrate is a silicon wafer.
[0046] S200 , forming a positive electrode fine grid and a negative electrode fine grid based on one side of the substrate.
[0047] In this embodiment, a photoresist is used to cover the surface of the silicon wafer, and then a light source is used to expose the surface, and a pre-designed printing screen pattern is printed on the photoresist. The illuminated portion forms an area on the substrate where the positive electrode fine grid and the negative electrode fine grid need to be deposited, and a layer of metal, such as aluminum, copper, etc., is deposited in these two areas as electrode materials. This step is usually completed by physical vapor deposition or sputtering deposition to form fine grid lines. After the deposition is completed, an etchant is used to selectively etch the deposited metal, and only the preset grid line portion is retained, and the rest is removed, leaving precise electrode lines.
[0048] Exemplarily, the positive electrode fine grid and the negative electrode fine grid regions on the substrate are etched along the substrate thickness direction, and the positive electrode fine grid region and the negative electrode fine grid region are etched to different depths. It can be understood that the positive electrode fine grid and the negative electrode fine grid are etched to different depths on the backlight side of the battery by using a laser windowing process, that is, the positive and negative electrode regions are isolated to reduce leakage.
[0049] Exemplarily, the material used for printing the positive and negative fine grids belongs to the burn-through type slurry. The burn-through type slurry contains a high content of metal particles and a low viscosity, and can penetrate into the microscopic pores or thin layers of the silicon wafer to form a stable conductive connection, especially on the fine grid lines, ensuring high-density electrode deposition, which helps to improve efficiency and uniformity. It can be seen that the burn-through slurry reduces interface defects and improves the long-term stability of the battery because it penetrates into the silicon wafer.
[0050] For example, the line width of the positive electrode fine grid and the negative electrode fine grid ranges from 13μm to 16μm. In order to reduce costs and increase efficiency, the printing screen here uses a high-mesh and fine-line diameter model.
[0051] S300, forming a positive main grid on the substrate based on the positive fine grid, the positive main grid is connected to the positive fine grid; forming a negative main grid on the substrate based on the negative fine grid, the negative main grid is connected to the negative fine grid, and the negative main grid and the positive main grid are located on the same side of the substrate.
[0052] In this embodiment, a specific conductive paste, such as non-burn-through aluminum or copper paste, is evenly applied to the pre-cleaned silicon wafer surface through a pre-designed printing stencil pattern. The printing stencil is covered on the silicon wafer, and then the photoresist is exposed with ultraviolet light or other light sources. The unexposed part will be dissolved by the subsequent developer, and the illuminated part will be retained as the position of the future grid line. The developed silicon wafer is corroded by chemical or physical methods, leaving only the slurry in the exposed area as the positive and negative main grid lines, and the rest is removed.
[0053] Exemplarily, the material used to print the positive busbar and the negative busbar is a non-burn-through slurry. The non-burn-through slurry contains fewer metal particles and has a higher viscosity. It is more difficult to penetrate deep into the silicon wafer, but stays on the surface. It can form a stable electrode on the surface that does not penetrate deep into the silicon wafer. In addition, the non-burn-through slurry reduces the risk of cracking caused by thermal stress between the electrode and the silicon wafer.
[0054] For example, the line width of the positive and negative main grids ranges from 50μm to 80μm. The purpose is to reduce the current loss by thickening the line when the current line is designed to be long and the current loss is large.
[0055] S400, disconnecting the negative electrode main grid to form a reserved channel, the reserved channel is used for connecting the positive electrode fine grid with the positive electrode main grid.
[0056] In the disclosed embodiment, by printing the pattern of the screen, when printing and forming the negative main grid, the negative main grid is disconnected to form a reserved channel for the positive fine grid to be connected to the positive main grid, so as to separate the positive and negative electrodes, so that the positive and negative currents can be derived, reducing the current loss, thereby improving the battery efficiency of the back contact battery. It should be noted that the screen for printing the positive main grid and the negative main grid can be selected from two materials, namely metal steel plate and gridless polyimide. The advantage of the metal steel plate is that the printing life is longer, which can reach more than 700,000 pieces / block.
[0057] Exemplarily, an insulating layer is formed at the reserved channel formed by the disconnection of the negative main grid, and is formed by a process of printing an insulating layer slurry, mainly to insulate and isolate the reserved channel formed by the disconnection of the negative main grid to prevent the disconnected negative main grid and the positive main grid passing through the reserved channel from forming adhesion.
[0058] In some embodiments, in the entire preparation method, three printing processes are performed to form the positive electrode fine grid, the negative electrode fine grid, the positive electrode main grid and the negative electrode main grid respectively, so that the positive electrode main grid and the negative electrode main grid can be printed at one time. For example, the first printing process forms the positive electrode fine grid; the second printing process forms the negative electrode fine grid; and the third printing process forms the positive electrode main grid and the negative electrode main grid, which reduces the order of printing processes, improves printing efficiency, and reduces production costs.
[0059] It should be noted that during the subsequent use of the back-contact battery, one probe in the probe row at the reserved channel needs to be removed to ensure that there is no contact between the probe and the positive main grid at the negative main grid isolation point to avoid leakage of the positive and negative electrodes.
[0060] Based on the above method, the embodiment of the present disclosure also provides a crystalline silicon solar cell corresponding to the above method, such as Figure 2-5 As shown, Figure 2 is a schematic diagram of a complete graphic printing of a crystalline silicon solar cell electrode provided by an embodiment of the present disclosure, Figure 3 is a schematic diagram of a battery printing positive electrode screen provided by an embodiment of the present disclosure, Figure 4 is a schematic diagram of a battery printed negative electrode screen provided by an embodiment of the present disclosure, Figure 5 It is a schematic diagram of the printed positive main grid and negative main grid of the battery provided by the embodiment of the present disclosure.
[0061] The battery includes a substrate, a positive electrode fine grid, a negative electrode fine grid, a positive electrode main grid and a negative electrode main grid: the positive electrode fine grid is located on one side of the substrate; the negative electrode fine grid and the positive electrode fine grid are located on the same side of the substrate, and the negative electrode fine grid and the positive electrode fine grid are staggered; the positive electrode main grid and the negative electrode main grid are formed on the substrate based on the positive electrode fine grid, and the positive electrode main grid is connected to the positive electrode fine grid; the negative electrode main grid is formed on the substrate based on the negative electrode fine grid, and the negative electrode main grid is connected to the negative electrode fine grid, and the negative electrode main grid and the positive electrode main grid are located on the same side of the substrate.
[0062] exist Figure 2 In the embodiment, the positive electrode fine grid, the negative electrode fine grid, the positive electrode main grid and the negative electrode main grid are all covered on the substrate. Figure 3 In the figure, only the schematic diagram of the screen with a straight fine grid is shown. Figure 3 A plurality of pores are left in the lateral direction to allow the positive electrode main grid to be accommodated and connected with the positive electrode fine grid. Figure 3 A plurality of pores are left in the vertical direction to allow the positive electrode fine grid to be accommodated and connected to the positive electrode main grid. Figure 4 A plurality of pores are left in the vertical direction to allow the negative electrode fine grid to be accommodated and connected to the negative electrode main grid. Figure 5 A plurality of positive main grids and negative main grids are alternately arranged in the vertical direction, a plurality of positive main grids are arranged at intervals in the lateral direction, and the positive main grids arranged at intervals in the lateral direction are arranged close to the edge of the printing screen so that the positive main grids can be printed at the edge of the substrate.
[0063] like Figure 6 As shown, Figure 6 It is an enlarged schematic diagram of the negative electrode main grid being disconnected to form a reserved channel provided by an embodiment of the present disclosure. The negative electrode main grid is disconnected to form a reserved channel c, and the reserved channel c is used to connect the positive electrode fine grid to the positive electrode main grid.
[0064] Exemplarily, the positive main gate includes a positive first main gate b1 and a positive second main gate b2 located on the substrate, and the positive second main gate is close to the edge of the substrate; the negative main gate includes a negative first main gate a1 and a negative second main gate a2 located on the substrate, and the negative second main gate a2 is close to the edge of the substrate, and the negative second main gate a2 is disconnected to form a reserved channel c.
[0065] It can be understood that a1 and a2 are both negative main grids, and the middle part is a disconnected design. The disconnected area is mainly to reserve a channel for collecting current at the edge of the positive main grid; b1 and b2 are both positive main grids, b1 is a normal positive main grid, and b2 is a special design structure that introduces the edge positive current into the positive main grid.
[0066] For example, the positive first main grid b1, the negative first main grid a1 and the negative second main grid a2 are arranged parallel to each other, the positive second main grid b2 is perpendicular to the positive first main grid a1, and a plurality of reserved channels c are arranged at intervals along the extension direction of the negative second main grid a2, and each positive second main grid b2 passes through the reserved channel c and is connected to the positive fine grid through the positive first main grid a1.
[0067] Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.
Claims
1. A method for preparing a crystalline silicon solar cell, characterized in that: The method comprises, providing a substrate; forming a positive electrode fine grid and a negative electrode fine grid based on one side of the substrate; Forming a positive main grid on the substrate based on the positive fine grid, wherein the positive main grid is connected to the positive fine grid; Based on the negative electrode fine grid forming a negative electrode main grid on the substrate, the negative electrode main grid is connected to the negative electrode fine grid, and the negative electrode main grid and the positive electrode main grid are located on the same side of the substrate; A reserved channel is formed by breaking on the negative electrode main grid, and the reserved channel is used for connecting the positive electrode fine grid with the positive electrode main grid.
2. The method according to claim 1, characterized in that The forming of the positive electrode fine grid and the negative electrode fine grid based on one side of the substrate comprises: The positive electrode fine grid and the negative electrode fine grid regions on the substrate are etched along the thickness direction of the substrate, and the etching depths of the positive electrode fine grid and the negative electrode fine grid regions are different.
3. The method according to claim 1, characterized in that The method of disconnecting the negative electrode main grid to form a reserved channel, wherein the reserved channel is used for connecting the positive electrode fine grid with the positive electrode main grid, comprises: An insulating layer is formed at the reserved channel formed by disconnecting the negative electrode main grid.
4. The method according to any one of claims 1 to 3, characterized in that: The method comprises: The first printing process forms the positive electrode fine grid; A second printing process forms the negative electrode fine grid; The third printing process forms the positive electrode main grid and the negative electrode main grid.
5. The method according to claim 2, characterized in that: The material used for printing the positive electrode fine grid and the negative electrode fine grid is a burn-through type slurry, and the material used for printing the positive electrode main grid and the negative electrode main grid is a non-burn-through slurry.
6. The method according to any one of claims 1 to 3, characterized in that: The line width of the positive electrode main grid and the negative electrode main grid ranges from 50 μm to 80 μm.
7. The method according to any one of claims 1 to 3, characterized in that: The line width of the positive electrode fine grid and the negative electrode fine grid ranges from 13 μm to 16 μm.
8. A crystalline silicon solar cell, characterized in that: The battery comprises: substrate; A positive electrode fine grid is located on one side of the substrate; A negative electrode fine grid is located on the same side of the substrate as the positive electrode fine grid, and the negative electrode fine grid and the positive electrode fine grid are staggered; A positive electrode main grid and a negative electrode main grid, the positive electrode main grid is formed on the substrate based on the positive electrode fine grid, and the positive electrode main grid is connected to the positive electrode fine grid; Based on the negative electrode fine grid forming a negative electrode main grid on the substrate, the negative electrode main grid is connected to the negative electrode fine grid, and the negative electrode main grid and the positive electrode main grid are located on the same side of the substrate; A reserved channel is formed by breaking on the negative electrode main grid, and the reserved channel is used for connecting the positive electrode fine grid with the positive electrode main grid.
9. The crystalline silicon solar cell according to claim 8, characterized in that: The positive electrode main grid includes a positive electrode first main grid and a positive electrode second main grid located on the substrate, and the positive electrode second main grid is close to the edge of the substrate; The negative electrode main grid includes a negative electrode first main grid and a negative electrode second main grid located on the substrate, the negative electrode second main grid is close to the edge of the substrate, and the negative electrode second main grid is disconnected to form the reserved channel.
10. The crystalline silicon solar cell according to claim 9, characterized in that: The positive first main grid, the negative first main grid and the negative second main grid are arranged parallel to each other, the positive second main grid is perpendicular to the positive first main grid, a plurality of the reserved channels are arranged at intervals along the extension direction of the negative second main grid, and each of the positive second main grids passes through the reserved channel and is connected to the positive fine grid through the positive first main grid.