Inkjet printer and automated metallization system for forming cross-overs for thin film solar modules

Abstract

Embodiments of this application provide an inkjet printer for forming cross-wires of a thin-film solar module. The cross-wires are located on the surface of the front electrode layer of the thin-film solar module away from the substrate and include mutually perpendicular G1 grid groups and G2 grid groups. A groove for forming the G2 grid groups is located on the surface of the front electrode layer away from the substrate. The inkjet printer includes: a controller; and at least one inkjet printhead linearly movable relative to the thin-film solar module. Each of the at least one inkjet printhead includes a plurality of nozzles arranged in a row. The plurality of nozzles includes a first group of nozzles and a second group of nozzles. The distance between two adjacent nozzles in the first group of nozzles is equal to the distance between two adjacent G1 grid lines in the G1 grid group. Similar to the first group of nozzles, a second group of nozzles is distributed between adjacent nozzles of the first group of nozzles. A controller is configured to control at least one inkjet printhead to move linearly relative to the thin-film solar module in a direction perpendicular to the groove, and to control the first and second groups of nozzles in each of the at least one inkjet printheads to print conductive ink onto the surface of the front electrode layer away from the substrate, thereby forming a G1 grid line group and a G2 grid line group. The first group of nozzles in each of the at least one inkjet printheads is controlled by the controller to continuously print conductive ink in a direction perpendicular to the groove, and the second group of nozzles in each of the at least one inkjet printheads is controlled by the controller to print conductive ink into the groove when the inkjet printhead moves above the groove in a direction perpendicular to the groove.

Description

Technical Field

[0001] This application relates to the field of solar energy technology, and more specifically to an inkjet printer for forming cross-wires of thin-film solar modules and an automated metallization system having the inkjet printer. Background Technology

[0002] Typically, thin-film solar cells consist of a back electrode layer, an absorber layer, a buffer / i layer, and a front electrode layer, arranged sequentially. Due to the low voltage and large area of ​​solar cells, most thin-film solar modules are designed to consist of multiple solar cells connected in series monolithically to avoid high current losses. However, this increases the total operating voltage of the thin-film solar module.

[0003] In addition, such as Figure 1 As shown, the layers in a solar cell are interconnected. These layers are separated by lines P1, P2, and P3. Lines P1 and P3 insulate the rear electrode layer from the front electrode layer, while line P2 serves as the electrical contact between the rear and front electrode layers, used for series connection between two adjacent cells. Since the structural region formed by lines P1, P2, and P3 does not generate electrical energy, it is often called a "dead zone." Figure 2 As shown.

[0004] To optimize the power conversion efficiency of solar cells, it is common practice to consider increasing the transmittance of the front electrode layer and further increasing the generated photocurrent, for example, by reducing its thickness. However, this leads to an increase in the sheet resistance of the front electrode layer, resulting in conduction losses. To reduce these conduction losses in the front electrode layer, highly conductive narrow metal grid lines (referred to as type I grid lines) can be incorporated into the front electrode layer to improve the associated conductivity; this is known as the metallization process in solar module manufacturing. In the metallization process, type I grid lines are printed laterally or perpendicularly to the P1 / P2 / P3 scribe lines at periodic intervals onto the top of the cell's front electrode layer. The type I grid lines are also continuously printed on the front electrode layer of the solar cell. The P3 scribe line interrupts the type I grid lines to prevent short circuits between the front electrode of one cell and the front electrode of its adjacent cell.

[0005] Type I grid lines can reduce conduction losses in the front electrode layer. However, due to the light-blocking effect of the grid lines, they also increase the dead area and further cause additional light loss. Furthermore, the application of Type I grid lines can lead to concentrated current at the cell ends. In the case of monolithically interconnected cells, the current collected at the Type I grid lines flows to the end of the cell and needs to be evenly distributed at the beginning of the next cell. Otherwise, further conduction losses will occur in the front and rear electrode layers.

[0006] To this end, additional metal grid lines, referred to as Type II grid lines, are printed within the dead zone and perpendicular to the Type I grid lines. The Type I grid lines are denoted by G1 and are perpendicular to the P2 scribe line; the Type II grid lines are denoted by G2 and are printed precisely on or parallel to the P2 scribe line. The purpose of printing the G2 grid lines is to uniformly distribute current along the P2 scribe line interconnect between the two G1 grid lines and to reduce current losses caused by the increased current distribution from the G1 grid lines at the beginning of the next solar cell. Because the G2 grid lines are located in the dead zone, they do not cause additional light loss due to shading. Furthermore, the G2 grid lines can increase photocurrent generation, which helps light to be reflected at the G2 grid lines to the back of the upper film / cover glass and further into the effective cell region.

[0007] Therefore, for precise optoelectronic design of dead zones, the G2 gate line needs to be printed precisely. Furthermore, when G2 crosses the edge of the P3 scribe line, it may cause current shunting, and when G2 crosses the lower edge of the P1 scribe line (in... Figure 2 (In the middle), it may cause light loss in the effective battery area.

[0008] Mass production of thin-film solar modules using metal grid lines (G1 and G2 grid lines) to enhance the front contact typically requires manufacturing processes with low capital expenditure costs, short production cycles, and high productivity. Furthermore, the metal grid lines (G1 and G2 grid lines) need to be printed in two completely different orientations, 0° and 90°. Achieving this requires additional precision handling / alignment equipment to change the printing / machine orientation, or double the number of printing and conveying devices to complete the printing of the G1 and G2 grid lines. Therefore, this increases capital expenditure costs and production cycle time. In addition, potential misalignment during the rotation / handling of the thin-film solar module can also lead to G2 grid line positioning errors.

[0009] In the prior art, commercial thin-film / CIGS photovoltaic manufacturers (Solibro Hi-Tech GmbH / Beijing Apollo Dingrong Solar Energy Technology Co., Ltd.) or (NICE Solar Energy GmbH) and their related research institutions (Department of Mechanical Engineering, Tsinghua University, Beijing; National Institute of Clean and Low-Carbon Energy) have proposed methods for printing metal grid lines on the front electrode layer of CIGS solar cell modules.

[0010] Solibro Hi-Tech GmbH offers a method called ALD (Aluminum Line Deposition), which uses thermal evaporation to deposit aluminum wire structures through a mask. This method has the following drawbacks: 1) low productivity and yield using masks; 2) high cost of special masks used for producing large-area components; 3) high material waste due to evaporation; 4) difficult mask maintenance; and 5) limitation by the width of the metal grid lines (the mask opening is too narrow, less than a few hundred micrometers, and easily clogged during / after use). The above-mentioned limitations relate to the deposition of general metal grid lines, primarily concerning G1 grid lines. When using thermal evaporation to deposit G2 grid lines, it is expected that G1 and G2 grid lines will be difficult to deposit simultaneously due to the shading effect.

[0011] NICE Solar Energy GmbH uses screen printing to print G1 grid lines and electron beam evaporation to deposit G2 grid lines. Screen printing is unsuitable for printing G1 grid lines on large-area solar cell modules due to key technical limitations. The larger the printed pattern, the lower the printing accuracy of the G1 grid lines in the central area of ​​a large-size (e.g., >1m²) printing area, and the line shape cannot be maintained due to the lower stiffness of the large central mesh openings. Furthermore, printing narrow lines using screen printing requires high-quality screens, such as hardened stainless steel calendered screens or knot-free screens. For full-size thin-film solar modules (e.g., >1m²), these large-size, high-quality screens are very difficult and expensive to manufacture. Moreover, the screen is prone to clogging and difficult to clean during the grid line printing process. Typically, Si-PV (6”×6”) screens are discarded without cleaning after some printing due to their low cost. Besides the high cost of screen printing for large thin-film solar modules, changing the grid line spacing is also very inflexible when adjusting the printing pattern for production samples.

[0012] Furthermore, the following drawbacks exist when printing G2 grid lines using screen printing technology. For simultaneous printing of G1 and G2 grid lines, the printing accuracy and linewidth of the G2 grid lines are significantly limited because the opening makes it difficult to maintain the stiffness of the screen in both directions (0° and 90°). Loss of screen stiffness leads to decreased accuracy and wider linewidth. Consequently, the printed grid lines may be S-shaped. As mentioned earlier, optimal printing of the G2 grid lines requires very precise placement near the dead zone of the P2 scribe line, rather than crossing the edges of the P1 and P3 scribe lines. Otherwise, the G2 grid lines will generate additional light loss or shunting in the effective cell area of ​​the cell. Since the produced thin-film solar modules have a very large P2 scribe line process window, the P2 scribe line spacing and shape vary considerably. Due to the inherently inflexible printing strategy of screen printing, rapid adjustments during production are almost impossible. For the alternative two-step printing of G1 and G2 grid lines, i.e., printing the G2 grid line after printing the G1 grid line, the following problems exist. Unlike double-sided printing (used in Si-PV to print two layers of material to increase the line height of G1), the uncured and flexible G1 grid lines are easily damaged by the squeegee when printing G2 grid lines at a 90° angle. If the printed G1 grid lines are cured first, followed by the G2 grid lines, then both G1 and G2 grid lines require two curing processes. Therefore, thin-film solar modules may be damaged due to overheating. Furthermore, the two printing and curing processes increase capital expenditure and operating costs.

[0013] Besides traditional screen printing, there are alternative rotary screen printing methods for wire printing, but these are only applicable to Si-PV (6”x6” wafers). For large-area thin-film solar module applications, rotary screen printing suffers from similar problems to traditional screen printing. For large print widths (600–1300 mm), the selected rotary tube material struggles to maintain sufficient rigidity, severely impacting print accuracy and grid line width. In the worst-case scenario, the grid lines in the central area of ​​the entire solar module will be S-shaped.

[0014] Furthermore, the electron beam evaporation process for G2 grid lines, as reported by Nice Solar Energy GmbH, is only suitable for laboratory scale and not for large-scale production because it is a full-area coating process. Using this method presents similar problems and limitations to using thermal evaporation methods, primarily low yield and high cost.

[0015] In existing technologies, there are other process methods such as aerosol jet printing or dispensing, which are relatively new technologies for metallization processes and still have significant process stability issues. Aerosol jet nozzles and dispensing nozzles are prone to clogging by metal particles during long-term printing, leading to frequent downtime. Furthermore, the high-end development of these two methods is still in its early stages. These two methods can print a maximum of 5–10 grid lines (G1) simultaneously. For large-area thin-film solar modules (up to 1000 G1 lines and several hundred G2 lines), many printing channels are required, meaning that aerosol jet printing currently has very low production volumes. Further increasing the number of nozzles used for dispensing or aerosol jetting, as an improvement over inkjet printing, is not easy because the horizontal distribution of paste / aerosol in the printhead is extremely challenging. Currently, 10 nozzles are almost the bottleneck for both technologies. Additionally, by changing the machine / printing orientation for dispensing and aerosol jetting methods, it is possible to print G2 grid lines as perpendicular to the G1 grid lines as possible.

[0016] In addition, several other metallization methods exist. These methods use conventional inkjet printing technology to apply metal grid lines to thin-film organic PV modules or silicon solar modules. In these metallization methods, inkjet printing is used to apply linear grid lines, i.e., G1 grid lines. The formation of this linear pattern is achieved solely through the overlapping of droplets ejected from the same nozzle in one printing direction. However, in the process of printing G2 grid lines, the solar module must be rotated to print the G2 grid lines in a direction perpendicular to the printing direction of the G1 grid lines. Furthermore, the droplet spacing for the G2 grid lines is several hundred micrometers, and they cannot be joined in a direction perpendicular to the G1 grid lines. In short, without additional rotation / processing to print the G1 and G2 grid lines, these conventional inkjet printing strategies cannot meet the requirements of low cycle times and high-yield mass production.

[0017] Various inkjet metallization production tools have been disclosed in the prior art. However, these tools are either focused on Si-PV (6”×6”) or on linear in-line printing process integration for flexible thin-film devices. In these tools, linear patterns of G1 grid lines can be inkjet-printed on large-area thin-film solar modules through the number of printheads or multi-step printing. However, for G2 grid lines, these tools require a change in printing / machine orientation. Therefore, without additional rotation / processing to print both G1 and G2 grid lines, these tools cannot meet the requirements of low cycle time and high throughput for large-scale production.

[0018] Therefore, there is a need for a method and inkjet printer capable of printing G1 and G2 grid lines along a single machine / printing direction to meet the requirements of low production cycle and high throughput for mass production without additional rotation / processing to print G1 and G2 grid lines, as well as to meet the following requirements: linewidth control, printing accuracy, compatibility with more complex geometries (e.g., interdigitated), compatibility with large-area solar modules, and reduced material consumption. Summary of the Invention

[0019] The purpose of this application is to provide an inkjet printer for forming cross-wires in thin-film solar modules, which is capable of printing cross-wires along a machine / printing direction.

[0020] This application provides an inkjet printer for forming cross-wires in a thin-film solar module. The cross-wires are located on the surface of the front electrode layer of the solar module away from the substrate of the thin-film solar cell module. The cross-wires include mutually perpendicular G1 grid groups and G2 grid groups. A groove for forming the G2 grid group is located on the surface of the front electrode layer away from the substrate. The inkjet printer has a controller and at least one inkjet printhead capable of linear movement relative to the thin-film solar module. Each of the at least one inkjet printhead includes a plurality of nozzles arranged in a row. The plurality of nozzles includes a first group of nozzles and a second group of nozzles. The distance between two adjacent nozzles in the first group of nozzles is the same as the spacing between two adjacent G1 grid lines in the G1 grid group. The second group of nozzles is distributed in the... Between adjacent nozzles in the first group of nozzles, the controller is configured to control the at least one inkjet printhead to move linearly relative to the thin-film solar module in a direction perpendicular to the groove, and to control the first group of nozzles and the second group of nozzles of each of the at least one inkjet printheads to print conductive ink on the surface of the front electrode layer away from the substrate to form the G1 grid line group and the G2 grid line group, wherein the first group of nozzles of each of the at least one inkjet printheads is controlled by the controller to continuously print conductive ink in a direction perpendicular to the groove, and the second group of nozzles of each of the at least one inkjet printheads is controlled by the controller to print conductive ink into the groove when the inkjet printhead moves above the groove in a direction perpendicular to the groove.

[0021] In embodiments of this application, each G1 grid line in the G1 grid line group is formed by overlapping droplets of conductive ink printed by the same nozzle in a direction perpendicular to the groove.

[0022] In embodiments of this application, each G2 grid line in the G2 grid line group is formed by using capillary force to cause conductive ink printed into the groove to flow along the groove.

[0023] In the embodiments of this application, the conductive ink is a nanoparticle type or a metal-organic-composite precursor type ink.

[0024] In embodiments of this application, the diameter of the droplets of conductive ink printed by each of the plurality of nozzles is 40 μm to 100 μm.

[0025] In the embodiments of this application, the inkjet printing speed of the inkjet printer is 300-700 mm / s.

[0026] Embodiments of this application also provide an automated metallization system for forming cross-wires of a thin-film solar module, comprising an inkjet printer according to embodiments of this application, a first online eddy current measuring device, a curing oven, an online inspection camera, and a second online eddy current measuring device. The thin-film solar module is processed sequentially by the first online eddy current measuring device, the inkjet printer, the curing oven, and the second online eddy current measuring device via a conveyor belt. The thin-film solar module is inspected by the online inspection camera after and / or before being processed by the curing oven. The first online eddy current measuring device is configured to measure the resistivity of the thin-film solar module. The inkjet printer is configured to generate G1 and G2 grid lines on the front electrode layer of the thin-film solar module. The curing oven is configured to cure the G1 and G2 grid lines on the front electrode layer of the thin-film solar module. The online inspection camera is configured to inspect the linewidth and defects of the G1 and G2 grid lines. The second online eddy current measuring device is configured to measure the resistivity of the thin-film solar module with the cured G1 and G2 grid lines.

[0027] Embodiments of this application also provide a system for forming thin-film solar modules, the system including an inkjet printer according to embodiments of this application.

[0028] In embodiments of this application, the system further includes a substrate receiving device suitable for receiving a substrate; one or more absorber layer deposition cluster devices having at least one process chamber adapted to deposit photovoltaic layer stacks for generating electrical energy on the surface of the substrate; one or more post-electrode layer deposition devices; one or more photovoltaic stack edge sweeping devices; solar cell encapsulation devices; autoclave devices; automatic junction box connection devices; and one or more quality inspection devices suitable for testing and evaluating fully formed thin-film solar modules.

[0029] The inkjet printer for forming intersecting lines according to embodiments of this application is a novel inkjet printer capable of self-aligning printing of G2 and G1 grid lines in the same machine / printing direction. Compared to conventional inkjet printers or other existing devices for printing metal grid lines, the inkjet printer for forming intersecting lines according to embodiments of this application exhibits various advantages in terms of low cycle time, high throughput, low capital expenditure cost, good linewidth control, better grid line aspect ratio and positioning accuracy, compatibility with more complex geometries, compatibility with large-area components, and reduced material waste. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of this application and the prior art, the drawings used in the embodiments and the prior art are briefly described below. Obviously, the drawings described below are only some embodiments of this application. The same reference numerals in the drawings indicate the same or similar elements.

[0031] Figure 1 A cross-sectional view of a single thin-film solar cell module according to an embodiment of this application;

[0032] Figure 2 for Figure 1 A top view of a portion of a single thin-film solar cell;

[0033] Figure 3 This is a top view of a thin-film solar module with intersecting wires according to an embodiment of this application;

[0034] Figure 4 This is a flowchart of a method for forming cross-wires for a thin-film solar module according to an embodiment of this application;

[0035] Figure 5 This is a diagram illustrating the flow of conductive ink in a groove under capillary force.

[0036] Figure 6 A diagram illustrating the formation of G2 grid lines by precisely printing conductive ink into the grooves;

[0037] Figure 7 A perspective view of an inkjet printhead printing along the machine direction according to an embodiment of this application;

[0038] Figure 8 This is a top view of an inkjet printhead printing G1 grid lines along the machine direction according to an embodiment of this application;

[0039] Figure 9 The formation of the G1 gate line is shown;

[0040] Figure 10A perspective view of an inkjet printhead printing along the machine direction according to an embodiment of this application;

[0041] Figure 11 The formation of the G2 gate line is shown;

[0042] Figure 12 An example of an automated metallization system for forming cross-wires of a thin-film solar module is shown according to an embodiment of this application;

[0043] Figure 13 An example process for forming cross conductors using an automated metallization system according to an embodiment of this application is shown;

[0044] Figure 14 A first example of the arrangement of an automated metallization system according to an embodiment of this application is shown;

[0045] Figure 15 A second example of the arrangement of an automated metallization system according to an embodiment of this application is shown;

[0046] Figure 16 A third example of the arrangement of an automated metallization system according to an embodiment of this application is shown;

[0047] Figure 17 A fourth example of the arrangement of an automated metallization system according to an embodiment of this application is shown;

[0048] Figure 18 A fifth example of the arrangement of an automated metallization system according to an embodiment of this application is shown. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in this application are within the scope of protection of this application.

[0050] Solar cell modules manufactured using thin-film PV technology can be referred to as thin-film solar modules. Examples of thin-film solar modules include copper indium gallium selenide (CIGS) thin-film solar modules, cadmium telluride (CdTe) thin-film solar modules, organic photovoltaic (OPV) thin-film solar modules, perovskite thin-film solar modules, dye-sensitized solar cell (DSSC) modules, and intrinsic thin-film heterojunction (HJT) solar module modules.

[0051] Thin-film solar cells typically consist of a back electrode layer, an absorber layer, a buffer / i layer, and a front electrode layer. Thin-film solar modules are usually formed by depositing multiple thin-film solar cells on a large substrate and interconnecting them in a monolithic series configuration. The specific structures and manufacturing methods of various thin-film solar modules are known in the art and will not be described in detail here.

[0052] like Figure 1 As shown, the layers in a thin-film solar cell are interconnected. These layers are separated by lines P1, P2, and P3. It's important to note that lines P1 and P3 insulate the back electrode layer from the front electrode layer, while line P2 serves as the electrical contact between the back and front electrode layers, connecting two adjacent cells in series. Since the structural region formed by lines P1, P2, and P3 does not generate electricity, it is often referred to as a "dead zone." Figure 2 As shown.

[0053] To optimize the power conversion efficiency of solar cells, it is common practice to consider increasing the transmittance of the front electrode layer and further increasing the generated photocurrent, for example, by reducing its thickness. However, this leads to an increase in the sheet resistance of the front electrode layer, resulting in conduction losses. To reduce these conduction losses in the front electrode layer, highly conductive narrow metal grid lines (referred to as type I grid lines) can be incorporated into the front electrode layer to improve the associated conductivity; this is known as the metallization process in solar module manufacturing. In the metallization process, type I grid lines are printed laterally or perpendicularly to the P1 / P2 / P3 scribe lines at periodic intervals onto the top of the front electrode layer of the solar cell. The type I grid lines are continuously printed on the front electrode layer of the solar cell. The P3 scribe line interrupts the type I grid lines to prevent short circuits between the front electrode of one cell and the front electrode of its adjacent cell.

[0054] Type I grid lines can reduce conduction losses in the front electrode layer. However, due to their light-blocking properties, they also increase the dead zone area, further contributing to additional light loss. Furthermore, the application of Type I grid lines leads to current concentration at the cell ends. In the case of monolithically interconnected cells, the current collected at the Type I grid lines flows to the cell ends and needs to be evenly distributed at the beginning of the next cell. Otherwise, further conduction losses will occur in the front and rear electrode layers.

[0055] To this end, additional metal grid lines, referred to as Type II grid lines, are printed in the dead zone and perpendicular to the Type I grid lines. The Type I grid lines are denoted by G1 and are perpendicular to the P2 scribe line; the Type II grid lines are denoted by G2 and are printed exactly on or parallel to the P2 scribe line. The purpose of printing the G2 grid lines is to uniformly distribute current and reduce current losses caused by the increased current distribution from the G1 grid lines at the beginning of the next solar cell, as the two grid lines G1 interconnect along the P2 scribe line. Since the G2 grid lines are located in the dead zone, they do not cause additional light loss due to shading. Furthermore, the G2 grid lines can increase photocurrent generation due to the reflection of light at the G2 grid lines onto the back of the upper film / cover glass and further into the effective cell region.

[0056] Embodiments of this application provide an inkjet printer and method for forming cross-wires in a thin-film solar module, which is capable of printing cross-wires in one machine / printing direction. Furthermore, the inkjet printer according to embodiments of this application is capable of performing the method for forming cross-wires in a thin-film solar module according to embodiments of this application.

[0057] Figure 1 This is a cross-sectional view of a single thin-film solar cell 1 according to an embodiment of this application. The thin-film solar cell 1 includes a rear electrode layer 12, an absorber layer 13, a buffer layer / i layer 14, a front electrode layer 15, P1 scribe lines, P2 scribe lines, and P3 scribe lines. The rear electrode layer 12 is disposed on a substrate 11. The absorber layer 13 is disposed on the rear electrode layer 12. The buffer layer / i layer 14 is disposed on the absorber layer 13. The front electrode layer 15 is disposed on the buffer layer / i layer 14.

[0058] The rear electrode layer 12, absorber layer 13, buffer / i layer 14, and front electrode layer 15 are separated by scribe lines P1, P2, and P3. Scribe line P1 extends through the rear electrode layer 12 and is filled with the material of absorber layer 13. Scribe line P2 extends through buffer / i layer 14 and absorber layer 13 and is filled with the material of front electrode layer 15. Scribe line P3 extends through front electrode layer 15, buffer / i layer 14, and absorber layer 13. Scribe lines P1 and P3 insulate the rear electrode layer 12 and front electrode layer 15, while scribe line P2 serves as the electrical contact between the rear electrode layer 12 and front electrode layer 15 for series connection of two adjacent cells. Since the structural region formed by scribe lines P1, P2, and P3 does not generate electricity, it is often referred to as a "dead zone." Figure 2 As shown.

[0059] See Figure 1 The cross-connects are located on the surface of the front electrode layer 15 away from the substrate 11. The cross-connects include gate line G1 and gate line G2.

[0060] Figure 2 yes Figure 1 A top view of a portion of a single thin-film solar module 1. See also Figure 1 and Figure 2 The G1 gate line is perpendicular to the P2 scribe line. The G2 gate line is printed exactly on and parallel to the P2 scribe line. The G1 gate line is perpendicular to the G2 gate line. The G2 gate line is located in the dead zone. Because the G2 gate line is located in the dead zone, it does not cause additional light loss due to light blocking. In addition, the G2 gate line can improve the generation of photocurrent, which is achieved by the light reflected at the G2 gate line onto the back of the upper film / front glass and further into the effective cell area.

[0061] Figure 3 This is a top view of a thin-film solar module 2 with intersecting wires according to an embodiment of this application. The thin-film solar module 2 may have multiple solar cells connected in series on a substrate. For example, as... Figure 3 As shown, the thin-film solar module 2 has three solar cells connected in series. Crossing wires are located on the surface of the front electrode layer of the thin-film solar module 2 away from the substrate and include G1 grid line groups and G2 grid line groups that are perpendicular to each other. The front electrode layer of the thin-film solar module 2 consists of the front electrode layers of multiple solar cells connected in series. The G1 grid line group includes multiple G1 grid lines spaced apart from each other. The G2 grid line group includes multiple G2 grid lines spaced apart from each other. In embodiments of this application, the distance between two adjacent G1 grid lines in the G1 grid line group can be 100 μm to 200 μm.

[0062] like Figure 3 As shown, each thin-film solar cell 1 in the thin-film solar module 2 has a G2 grid line located on and parallel to the corresponding P2 scribe line, and has a plurality of G1 grid lines spaced apart from each other.

[0063] Figure 4 A flowchart illustrating a method for forming cross-wires of a thin-film solar module according to an embodiment of this application is shown. This method can be implemented using inkjet printing technology. The method according to an embodiment of this application can be executed by an inkjet printer according to an embodiment of this application and may include steps S1 and S2.

[0064] In embodiments of this application, the inkjet printer may have at least one inkjet printhead 3 that is linearly movable relative to the thin-film solar module. Each inkjet printhead 3 includes a plurality of nozzles arranged in a row. Figure 9 and 10 As shown, the plurality of nozzles includes a first group of nozzles N1 and a second group of nozzles N2. The distance between two adjacent nozzles in the first group of nozzles N1 is the same as the distance between two adjacent G1 grid lines in the G1 grid line group (which is equal to the grid pitch). The second group of nozzles N2 is distributed among adjacent nozzles in the first group of nozzles N1.

[0065] In step S1, a plurality of grooves are formed on the surface of the front electrode layer away from the substrate.

[0066] The grooves on the surface of the front electrode layer are formed by the following process. For example... Figure 1 As shown, the buffer / i-layer 14 and absorber layer 13 exhibit grooves for forming the P2 scribe lines, referred to as P2 grooves. The P2 grooves are scribed through the buffer / i-layer 14 and absorber layer 13 by laser or mechanical scribing, extending to the back electrode. The front electrode layer is then printed over the entire CIGS stack. Thus, the P2 grooves are filled with the material of the front electrode layer. Another groove structure, namely the groove for forming the G2 gate line, is formed by laser or mechanical scribing on the surface of the front electrode layer away from the substrate at a location corresponding to the P2 groove.

[0067] In step S2, during the linear movement of the inkjet printhead relative to the thin-film solar module in a direction perpendicular to the groove, conductive ink is continuously printed through the first set of nozzles on the surface of the front electrode layer away from the substrate in a direction perpendicular to the groove to form the G1 grid line group, and when the inkjet printhead moves above the groove in a direction perpendicular to the groove, conductive ink is printed into the groove through the first set of nozzles and the second set of nozzles to form the G2 grid line group.

[0068] In this embodiment, each groove is located on and parallel to the corresponding P2 etch line. The width of the groove can be 20 μm to 30 μm.

[0069] In their research, the inventors discovered that after ink droplets are placed in the groove, the ink droplets flow within the groove under the influence of capillary force, such as... Figure 5 As shown. The width of the groove is typically 20μm to 30μm, which is much smaller than the diameter of the ink droplets, which ranges from 40μm to 100μm. For example... Figure 6 As shown, once the ink droplets printed along the machine / printing direction are precisely placed into the groove, these droplets can overcome the hundreds of micrometers of spacing between them to form continuous G2 grid lines within the groove through self-alignment. Otherwise, if these ink droplets are printed next to the groove, they will only form discrete points that result in additional shunting or optical loss when they are located in the effective cell area of ​​the solar module. The machine / printing direction is the direction in which the inkjet printhead moves linearly relative to the thin-film solar module. This direction is perpendicular to the groove on the front electrode layer, i.e., perpendicular to the P2 scribe line.

[0070] In one embodiment, the conductive ink used to form the G1 and G2 gate lines can be a nanoparticle type or a metal-organic composite precursor type ink. The main solid component used in the ink can be silver, copper, aluminum, or other conductive nanoparticles or their derivatives.

[0071] Figure 5 This is a diagram illustrating the flow of conductive ink in a groove under the influence of capillary force. Figure 6 This diagram illustrates how G2 grid lines are formed by precisely printing conductive ink into the grooves. (See diagram for reference.) Figure 5 As shown, after the conductive ink used for printing G2 grid lines is printed into the grooves, the conductive ink can flow along the grooves under the action of capillary force, thereby overcoming the hundreds of micrometers of spacing between droplets to form continuous G2 grid lines within the grooves through self-alignment. In this way, G2 grid lines can be formed during the printing of G1 grid lines along the machine / printing direction. That is, the inkjet printhead can print both G1 and G2 grid line groups along one machine / printing direction.

[0072] In one embodiment, the G1 and G2 grid groups can be printed in one step. Alternatively, the G1 and G2 grid groups can be printed separately. Regardless of the printing order of the G1 and G2 grid groups, the machine / printing orientation will remain unchanged. This can save space, capital expenditure costs, and cycle time.

[0073] In one embodiment, the G1 and G2 grid groups can be printed separately along the same machine / printing direction. For example, the G1 grid group can be printed first, and then the G2 grid group can be printed after the G1 grid group has been printed. Alternatively, the G2 grid group can be printed first, and then the G1 grid group can be printed after the G2 grid group has been printed. The following example illustrates the process of printing the G1 grid group first and then the G2 grid group.

[0074] Figure 7-11 The process of forming cross conductors of a thin-film solar module by first printing the G1 grid line group and then the G2 grid line group using an inkjet printer according to an embodiment of the present application is illustrated.

[0075] See Figure 7-11 Embodiments of this application also provide an inkjet printer for forming cross-wires of a thin-film solar module. In this embodiment, the inkjet printer includes a controller (not shown) and at least one inkjet printhead 3 linearly movable relative to the thin-film solar module. Each of the at least one inkjet printhead 3 includes a plurality of nozzles arranged in a row. Figure 9 and 10 As shown, the multiple nozzles include a first group of nozzles N1 and a second group of nozzles N2. The distance between two adjacent nozzles in the first group of nozzles N1 is the same as the spacing between two adjacent G1 grid lines in the G1 grid line group. The second group of nozzles N2 is distributed among adjacent nozzles in the first group of nozzles N1.

[0076] The controller controls the at least one inkjet printhead 3 to move linearly relative to the thin-film solar module in a direction perpendicular to the groove, and controls the first set of nozzles N1 and the second set of nozzles N2 in each of the at least one inkjet printheads to print conductive ink on the surface of the front electrode layer away from the substrate to form the G1 grid line group and the G2 grid line group.

[0077] The first set of nozzles N1 of each inkjet printhead 3 in at least one inkjet printhead is controlled by a controller to continuously print conductive ink along a direction perpendicular to the groove.

[0078] The second set of nozzles N2 of each inkjet printhead 3 in at least one inkjet printhead is controlled by a controller to print conductive ink into the groove when the inkjet printhead moves above the groove in a direction perpendicular to the groove.

[0079] Figure 7 A perspective view of the G1 grid line group printed along the machine direction by an inkjet printhead according to an embodiment of this application. Figure 8 This is a top view of the G1 grid line group printed along the machine direction by an inkjet printhead according to an embodiment of this application. Figure 9 This is an image showing the formation of the G1 grid lines.

[0080] See Figure 7 and Figure 8 The inkjet printhead moves relative to the thin-film solar module along the machine direction to print the G1 grid line group on top of the front electrode layer (or other interface layer) of the thin-film solar module, i.e., on the surface away from the substrate. Generally, the G1 grid lines are printed continuously in a direction perpendicular to the P2 scribe line. In this embodiment, the G1 grid line group is printed in one step across the entire thin-film solar module by the inkjet printhead. This method reduces production cycle time and increases productivity.

[0081] See Figure 9 Each G1 grid line in the G1 grid line group is formed by overlapping printing droplets in the machine direction, i.e., in the direction perpendicular to the P2 scribe line. To form narrower G1 grid lines with a width of 40–100 μm, the critical droplet size for forming a single G1 grid line can be 10–25 p1. See also Figure 9 The first set of nozzles N1 in the inkjet printhead is used to print droplets to form the G1 grid line group. The distance between two adjacent nozzles in the first set of nozzles N1 is the same as the spacing between two adjacent G1 grid lines in the G1 grid line group. During the printing of the G1 grid line group, the second set of nozzles N2 in the inkjet printhead is inactive, i.e., it does not print droplets.

[0082] Figure 10This is a perspective view of the G2 grid line group printed along the machine direction by an inkjet printhead according to an embodiment of this application. Figure 11 This is an image showing the formation of the G2 grid line group.

[0083] See Figure 10 The inkjet printhead moves relative to the thin-film solar module with the G1 grid line group in the same machine / printing direction as the G1 grid line group, i.e., perpendicular to the P2 scribe line, so that the G2 grid line group is printed on top of the front electrode layer (or other interface layer) of the thin-film solar module, i.e., on the surface away from the substrate. In this embodiment, the G2 grid line group is printed on the entire thin-film solar module in one step by the inkjet printhead. This method can reduce production cycle time and improve productivity.

[0084] See Figure 11 In this embodiment, the second set of nozzles N2 in the inkjet printhead is distributed between adjacent nozzles in the first set of nozzles N1. During the printing of each G2 grid line in the G2 grid line group, as the inkjet printhead moves along a direction perpendicular to the groove above the groove in the front electrode layer, all nozzles in the inkjet printhead (including the first set of nozzles N1 and the second set of nozzles N2) print conductive ink into the groove to form the G2 grid line. After the conductive ink enters the groove, it flows along the groove by means of capillary force, thereby forming the G2 grid line. In this way, the G2 grid line will remain in the groove and will not cross the edges of the P1 or P3 scribe lines. This reduces shunting or additional light loss problems.

[0085] In this embodiment, the G1 and G2 grid line groups can be formed in one step along the machine / printing direction. Specifically, as the inkjet printhead moves relative to the thin-film solar module along the machine / printing direction, i.e., along a direction perpendicular to the P2 scribe line, the controller controls the first set of nozzles N1 in the inkjet printhead 3 to continuously print conductive ink, and controls the second set of nozzles N2 in the inkjet printhead to print conductive ink only when the inkjet printhead moves over the groove in the front electrode layer. In this way, the G1 and G2 grid line groups can be formed in one step.

[0086] In one embodiment, G1 or G2 grid lines can be printed in single or multiple channels to achieve optimal linewidth and height, thereby obtaining optimal device performance in the solar cell module.

[0087] In one embodiment, after printing the G1 and G2 grid lines onto the surface of the front electrode layer (or other interface layer) of the thin-film solar module away from the substrate using inkjet printing, the printed G1 and G2 grid lines are cured / annealed to transform them into a blocky material with little or no organic residue in the granular structure. This method achieves good electrical conductivity. Therefore, the curing temperature for the G1 and G2 grid lines can be 120–250°C. The curing process can be carried out using various convection furnaces (such as batch furnaces, conveyor belt furnaces, or mixed hot air furnaces), radiant heating devices (infrared heating devices, ultraviolet curing devices, microwave curing devices, etc.), or conductive heating plates.

[0088] Furthermore, the inkjet printing of the G2 grid group along the same printing / machine direction as the G1 grid group, through self-alignment caused by capillary flow, cannot be achieved by other special non-contact printing technologies, such as dispensing or aerosol printing technologies.

[0089] Compared to inkjet printing (discrete in a point-to-point manner using piezoelectric crystals) of this application, printing is a continuous jetting method that injects a liquid film with a typical diameter of 20 micrometers to several hundred micrometers using hydraulic pressure. In the case of multi-nozzle printing, the single-nozzle unit size in printing is in the millimeter range (5-10 mm) compared to the nozzle spacing (100-200 μm) in inkjet printing. Furthermore, the viscosity of the conductive metal-specific ink used for printing is approximately 100-1000 times that of the conductive ink used in inkjet printing. Therefore, it is almost impossible to form the G2 grid line in the same printing direction as the G1 grid line by capillary force to induce the flow of the conductive metal-specific ink printed in the G2 groove. It should be noted that the G2 grid line can only be formed by using single-nozzle printing in a direction perpendicular to the G1 grid line.

[0090] Aerosol jetting is a method of jetting ink aerosols generated by ultrasonic or pneumatic atomization. This method can produce grid lines with typical widths of 5–20 μm. In this method, only a single aerosol nozzle can be used to print G2 grid lines in a direction perpendicular to the printing direction of G1 grid lines. For multi-nozzle aerosol jetting, the nozzle spacing is similar to that in printing. Aerosol jetting technology does not jet droplets (measured in picoliters in inkjet printing) or liquid streams; instead, it jets ink aerosols. Therefore, it is also impossible to induce ink aerosol flow in the G2 grooves via capillary action to form G2 grid lines in the same printing direction as G1 grid lines.

[0091] The method for forming cross-conductors of a thin-film solar module according to this application and the inkjet printer offer the following benefits: the front electrode layer with G2 grid lines can be significantly enhanced in terms of conductivity. The inherent shape of the groove located above and parallel to the P2 scribe line helps to limit the width of the G2 grid lines. The width of the groove allows for very narrow G2 grid lines, which is difficult to achieve with inkjet printing on ordinary substrate surfaces. Due to the narrower width of the G2 grid lines, the likelihood of them extending beyond the active region is further reduced, thereby reducing shunting or light loss. Furthermore, using the method and inkjet printer of this application, the G2 grid line group can be printed in the same machine / printing direction as the G1 grid line group, which can significantly save capital expenditure costs in equipment design and increase production output.

[0092] Unlike vacuum deposition using masks, inkjet printing allows for direct printing of G1 and G2 grid lines onto the target surface without unnecessary waste in the working chamber or mask. Compared to screen printing, inkjet printing offers greater flexibility in adjusting grid spacing and pattern design. Furthermore, inkjet printing has no size limitations for thin-film solar modules. Because inkjet printing is a digital process, it avoids the significant deviations in printing width and shape within certain areas of large substrates caused by the limited mechanical properties of screen printing. The printing accuracy of grid lines formed by inkjet printing is also far superior to that of traditional printing methods. Inkjet printing ensures that the inkjet-formed G2 grid lines accurately enter the grooves, thus avoiding shunting or additional light loss problems caused by inaccurate G2 grid line positioning.

[0093] The methods for forming the cross-connectors (G1 and G2 grid lines) and the related inkjet printing technology have been described above. For the mass production of thin-film solar modules with enhanced front contacts, an automated metallization production line is typically required to ensure that the cross-connectors (G1 and G2 grid lines) can be manufactured in a repeatable and reliable manner.

[0094] With intense price competition in silicon solar modules, a simple and low-cost one-step metallization method is strongly recommended for the production of thin-film solar modules. Furthermore, this method offers fast printing rates, high productivity, and high production volumes.

[0095] Compared to a 6” x 6” (15.24cm × 15.24cm) Si-PV wafer, a full-size thin-film solar module is typically much larger as a single piece during manufacturing. Its overall module length can range from 1200 to 2000 mm, and its width from 600 to 1300 mm. Therefore, a suitable method is needed to apply a uniform linewidth and height across the entire effective cell area to form intersecting conductors (G1 and G2 grid lines) on the thin-film solar module. Furthermore, the G1 and G2 grid lines need to be printed in two vertical directions, 0° and 90°. Achieving this requires high printing precision over the entire large area.

[0096] Embodiments of this application also provide an automated metallization system. This system may include an inkjet printer according to embodiments of this application. In this system, the inkjet printer is used to print a pattern of intersecting wires, i.e., a pattern of metal contact lines, on a substrate for a thin-film solar module, specifically on the front electrode layer of the thin-film solar module. In this pattern of intersecting wires, at least two sets of grid lines (G1 grid line set and G2 grid line set) are formed in different directions (e.g., 0° and 90°) relative to a P2 scribe line or groove. The inkjet printer is equipped with a printing workstation having at least one movable linear printhead with a plurality of fixed inkjet printing nozzles (including at least two sets of independently operable nozzles). During the printing process, the substrate moves or remains stationary only along one linear direction, and the printhead moves or remains stationary only in a direction parallel to the substrate transport direction. Furthermore, the at least two sets of nozzles do not always print simultaneously, but operate in such a way that the relative linear movement of the printhead and the substrate, along with the time-controlled printing of the at least two sets of nozzles, results in the formation of patterns for at least two grid line sets in different directions. Compared to conventional solar metallization systems / production lines that use inkjet printing or other standard metal grid printing technologies, the automated metallization system of this application exhibits several advantages in terms of low cycle time, high productivity, low capital expenditure costs, and better grid aspect ratio and positioning accuracy.

[0097] The automated metallization system according to embodiments of this application may further include at least one rapid curing oven, an online quality inspection device (e.g., an online inspection camera), and an online eddy current measurement device (e.g., an eddy current anisotropic sheet resistance device) to meet the high-yield mass production requirements of solar cell modules. The curing oven enables rapid thermal convection of the printed conductive cross-wires (G1 and G2 grid lines) to achieve optimal conductivity. The online quality inspection device automatically characterizes the properties of the formed cross-wires (G1 and G2 grid lines) to ensure their performance is within the desired performance range, and, in conjunction with further process steps, creates solar cell devices that meet the functional and performance specifications required by solar cell device manufacturers.

[0098] The automated metallization system according to embodiments of this application is based on a novel inkjet printing process for completing the G1 / G2 grid groups in one step along the same printing / machine direction according to embodiments of this application. Therefore, it can meet the requirements of thin-film solar module production: good linewidth control, flexible pattern design, reduced ink / material consumption essential for cost reduction, and high printing accuracy of the G1 and G2 grid groups over a large area. Furthermore, it can significantly save capital expenditure costs in equipment design and improve productivity.

[0099] During production, G1 and G2 grid lines are printed on top of the front electrode layer (or other interface layer) of the thin-film solar module using inkjet-printed conductive ink. The number of G1 grid lines printed on a full-size substrate can exceed 1000, while the number of G2 grid lines can exceed 200. The positioning accuracy of the G1 and G2 grid lines is ±5–10 μm in both directions parallel to and perpendicular to the P2 scribe line. Inkjet printing speeds can reach 300–700 mm / s, allowing for a low cycle time of 10–30 seconds per full-size substrate. In conventional G2 grid line printing, substrate rotation / processing and subsequent second alignment would add an extra 10–15 seconds of cycle time. During printing, the substrate can be maintained at a temperature of 25–85°C, achieved through thermal convection preheating or radiation preheating, or additional conductive heating during printing. This is to achieve narrow grid lines without overheating the print head.

[0100] For the curing process, the substrate needs to be heated rapidly to achieve its optimal conductivity. Therefore, the temperature of the substrate with grid lines can range from 120 to 250°C. The curing process can be carried out in various heat convection conveyor curing ovens, such as high-speed impact hot air curing ovens or infrared hot air hybrid curing ovens. The cycle time of the curing oven is 10 to 30 seconds. The conveyor speed inside the curing oven can reach 80 to 200 mm / s. High productivity can be achieved by using such an oven. Furthermore, the conveyor belt between the printing press, curing oven, online inspection camera, and online eddy current measurement device has a maximum conveying speed of 1000 mm / s.

[0101] Figure 12 An example of an automated metallization system for forming cross-wires of a thin-film solar module, according to an embodiment of this application, is shown. Figure 13 An example process for forming cross conductors using an automated metallization system according to an embodiment of this application is shown.

[0102] Figure 12The automated metallization system shown includes a first online eddy current measuring device 1201, an inkjet printer 1202, a curing oven 1204, an online inspection camera 1203, and a second online eddy current measuring device 1205. The inkjet printer 1202 and... Figure 7-11 The inkjet printer shown is the same.

[0103] See Figure 12 Thin-film solar modules can be processed sequentially via a conveyor belt by a first online eddy current measuring device 1201, an inkjet printer 1202, a curing oven 1204, and a second online eddy current measuring device 1205. The thin-film solar modules can be inspected by an online inspection camera 1203 before and / or after processing by the curing oven 1204. The first online eddy current measuring device 1201 can be used to measure the resistivity of the thin-film solar module. The inkjet printer 1202 can print G1 and G2 grid lines on the front electrode layer of the thin-film solar module. The curing oven 1204 can cure the G1 and G2 grid lines on the front electrode layer of the thin-film solar module. The online inspection camera 1203 can inspect the linewidth and defects of the G1 and G2 grid lines. The second online eddy current measuring device 1205 can measure the resistivity of the thin-film solar module with the cured G1 and G2 grid lines.

[0104] See Figure 12 and Figure 13During production, a quality inspection process 1303 is optional and can be performed before printing process 1302, between printing process 1302 and curing process 1304, or after curing process 1304. In this embodiment, the system is adapted to receive untreated substrates for thin-film solar modules from a feed robot (or upstream conveyor) 1207. In 1301, the resistivity of the substrate is measured by a first in-line eddy current measuring device 1201 before the printing process. In 1302, the coated substrate is conveyed to an inkjet printer 1202 where multiple printing-related steps are performed: particle removal / cleaning by an air knife 1209, surface energy modification by a certain pressure plasma treatment 1210, processing the substrate to a certain temperature level by a preheating device 1211 (thermal convection, radiation, or mixing), and printing G1 and G2 grid lines by using multiple printheads 1212 on heated or unheated suction tables. At 1304, the coated substrate with printed G1 and G2 grid lines is further conveyed to curing oven 1204 for curing. In the curing oven, a hybrid infrared emitter 1213 and a hot air impact chamber 1214 can be installed in the heating zone to rapidly cure the printed G1 and G2 grid lines to achieve high conductivity. To avoid thermal effects on subsequent electrical measurements, the coated substrate can be rapidly cooled to the desired temperature by an optional air cooler 1215 in the curing oven. At 1303, an in-line inspection camera 1203 can be used to inspect the width and defects (e.g., line breaks, line widening, etc.) of the printed G1 and G2 grid lines. The in-line inspection camera 1203 can be used for 2D optical inspection of line width and line defects. Figure 13 As shown, the in-line inspection camera 1203 can be located between the inkjet printer 1202 and the curing oven 1204 and / or after the curing oven 1204. When the grid structure, including the printed G1 and G2 grid lines, reaches its optimal conductivity after curing in the curing oven, in 1305, the second in-line eddy current measuring device 1205 again measures the resistivity of the coated substrate. The results measured by the in-line eddy current measuring device 1205 and the first eddy current measuring device can be used to evaluate the electrical performance of the G1 and G2 grid line groups. Finally, the thin-film solar module with the G1 and G2 grid line groups can be conveyed to the unloading robot (or downstream conveyor belt) 1208.

[0105] Figure 14-18 Various examples of the arrangement of automated metallization systems in a factory layout are shown. It should be noted that these embodiments only illustrate typical embodiments of this application and should not be considered as a limitation on the number of device units in an automated metallization system. Other embodiments with higher productivity are possible with this application.

[0106] Figure 14 A first example of the arrangement of an automated metallization system according to an embodiment of this application is shown. Figure 14 The automated metallization system shown includes, in sequence, a first online eddy current measuring device 1201, an inkjet printer 1202, a curing oven 1204, a second online eddy current measuring device 1205, and two online inspection cameras 1203. These devices are connected via a conveyor belt 1206. One of the two online inspection cameras is located between the inkjet printer 1202 and the curing oven 1204, while the other is located between the curing oven 1204 and the second online eddy current measuring device 1205. See also... Figure 14 The thin-film solar module is conveyed via conveyor belt 1206 from the feeding robot (or upstream conveyor belt) 1207 to the first online eddy current measuring device 1201. After the resistivity of the solar module is detected by the first online eddy current measuring device 1201, the solar module is conveyed to the inkjet printer 1202. The inkjet printer 1202 prints metal grid lines G1 and G2 on the surface of the front electrode layer of the solar module away from the substrate. The solar module with the printed grid lines G1 and G2 is conveyed to the online inspection camera 1203 for quality inspection, and then to the curing oven 1204 for curing the printed grid lines G1 and G2. The solar module with the cured grid lines G1 and G2 is conveyed to the online inspection camera 1203 for further quality inspection. Then, the solar module with the cured grid lines G1 and G2 is conveyed to the second online eddy current measuring device 1205 to measure the resistivity of the solar cell module again. Finally, the thin-film solar module with the cured grid lines G1 and G2 is conveyed to the unloading robot (or downstream conveyor belt) 1208.

[0107] Figure 15 A second example of the arrangement of an automated metallization system according to an embodiment of this application is shown. For clarity, only the following description is provided. Figure 15 The arrangement of the automatic metallization system shown is as follows Figure 14 The differences in arrangement. In Figure 15 In this case, there is no online inspection camera 1203 between the inkjet printer 1202 and the curing oven 1204. Figure 15 The automated metallization system shown has two parallel inkjet printers 1202. These two parallel inkjet printers 1202 are connected to a curing oven 1204 via conveyor belts. The solar panels are conveyed to the curing oven 1204 after being processed by either of the two parallel inkjet printers 1202.

[0108] Figure 16 A third example of the arrangement of an automated metallization system according to an embodiment of this application is shown. For clarity, only the following description is provided. Figure 16 The arrangement of the automated metal system shown Figure 15 The differences in arrangement. In Figure 16The automated metallization system shown includes two parallel inkjet printers 1202 and two parallel inkjet curing ovens 1204. The downstream ends of the two parallel inkjet printers 1202 are connected by a conveyor belt, allowing solar panels processed by either of the two inkjet printers 1202 to be conveyed to either of the two curing ovens 1204.

[0109] Figure 17 A fourth example of the arrangement of an automated metallization system according to an embodiment of this application is shown. For clarity, only the following description is provided. Figure 17 The arrangement of the automated metallization system shown is... Figure 16 The differences in arrangement. In Figure 17 The automated metallization system shown includes three parallel inkjet printers 1202 and three parallel inkjet curing ovens 1204. The downstream of the three parallel inkjet printers 1202 are connected by two conveyor belts, allowing the solar panels processed by any one of the three inkjet printers 1202 to be conveyed to any one of the three curing ovens 1204.

[0110] Figure 18 A fifth example of the arrangement of an automated metallization system according to an embodiment of this application is shown. For clarity, only the following description is provided. Figure 18 The arrangement of the automated metallization system shown is... Figure 14 The differences between the arrangements. Figure 18 The automated metallization system shown features a central circular processing system 1216. The central circular processing system 1216 is connected to the curing oven 1204 via a conveyor belt. Furthermore, the central circular processing system 1216 is connected to three inkjet printers 1202 via three separate conveyor belts. The feeding and unloading of the thin-film solar modules will occur on the same conveyor belt between the central circular processing system 1216 and the individual inkjet printers 1202. This arrangement allows for savings in capital expenditure costs for conveyor systems and in factory layout space.

[0111] In this application, the automated metallization system can have any number of inkjet printers 1202 and curing ovens 1204. Furthermore, the number of other devices is not limited in this application.

[0112] This application also relates to a system for forming thin-film solar modules. The system is capable of forming photovoltaic devices or solar cells using processing modules adapted to perform one or more steps in the solar module forming process. Automated solar cell factories are typically arrangements of automated processing components and automated equipment for forming solar cell devices. Therefore, an automated solar cell factory generally includes a system for forming thin-film solar modules. This system may include an inkjet printer according to embodiments of this application. The system may also include a substrate receiving device adapted to receive a substrate; one or more absorber layer deposition cluster devices having at least one process chamber adapted to deposit photovoltaic stacks for generating electricity on the surface of the substrate, such as silicon-containing layers, CIGS stacks, CdTe stacks, OPV stacks, perovskite stacks, DSSC stacks, or HIT stacks; one or more post-electrode layer deposition devices; one or more photovoltaic stack edge-sweeping devices; solar cell encapsulation equipment; autoclave equipment; automated junction box connection equipment; and one or more quality inspection devices suitable for testing and evaluating fully formed solar cell devices.

[0113] The inkjet printer and method for forming cross-wires of thin-film solar modules according to embodiments of this application is a novel inkjet printing process capable of self-aligning inkjet printing of G2 and G1 grid lines in the same machine / printing direction. Compared with conventional inkjet processes or other existing metal grid line printing technologies, the inkjet printer and method for forming cross-wires of thin-film solar modules according to embodiments of this application exhibit various advantages in terms of low cycle time, high throughput, low capital expenditure cost, good linewidth control, better grid line aspect ratio, and improved positioning accuracy, compatibility with more complex grid line placement designs, compatibility with large-area solar modules, and reduced material consumption.

Claims

1. An inkjet printer for forming cross-wires of a thin-film solar module, the cross-wires being located on the surface of the front electrode layer of the thin-film solar module away from the substrate, and comprising a G1 grid line group and a G2 grid line group perpendicular to each other, wherein a groove for forming the G2 grid line group is located on the surface of the front electrode layer away from the substrate. in, The inkjet printer has the following features: Controller; and At least one inkjet printhead is linearly movable relative to the thin-film solar module. Each of the at least one inkjet printhead includes a plurality of nozzles arranged in a row. The plurality of nozzles includes a first group of nozzles and a second group of nozzles. The distance between two adjacent nozzles in the first group of nozzles is the same as the distance between two adjacent G1 grid lines in the G1 grid line group. The second group of nozzles is distributed between adjacent nozzles in the first group of nozzles. The controller is configured to control the at least one inkjet printhead to move linearly relative to the thin-film solar module along a direction perpendicular to the groove, and to control the first set of nozzles and the second set of nozzles of each of the at least one inkjet printheads to print conductive ink on the surface of the front electrode layer away from the substrate to form the G1 grid line group and the G2 grid line group. The first set of nozzles in each of the at least one inkjet printheads is controlled by the controller to continuously print conductive ink along a direction perpendicular to the groove. The second set of nozzles of each of the at least one inkjet printheads is controlled by the controller to print conductive ink into the groove when the inkjet printhead moves above the groove in a direction perpendicular to the groove.

2. The inkjet printer according to claim 1, wherein, Each G1 grid line in the G1 grid line group is formed by overlapping droplets of conductive ink printed by the same nozzle in a direction perpendicular to the groove.

3. The inkjet printer according to claim 1, wherein, Each G2 grid line in the G2 grid line group is formed by using capillary force to cause conductive ink printed into the groove to flow along the groove.

4. The inkjet printer according to claim 1, wherein, The conductive ink is a nanoparticle or metal-organic-composite precursor ink.

5. The inkjet printer according to claim 1, wherein, The diameter of the conductive ink droplets printed by each of the plurality of nozzles is from 40 μm to 100 μm.

6. The inkjet printer according to claim 1, wherein, The inkjet printer has an inkjet printing speed of 300 to 700 mm / s.

7. An automated metallization system for forming cross conductors of a thin-film solar module, comprising an inkjet printer as described in any one of claims 1 to 6, a first online eddy current measuring device, a curing oven, an online inspection camera, and a second online eddy current measuring device, wherein, The thin-film solar module is processed sequentially via a conveyor belt by the first online eddy current measuring device, the inkjet printer, the curing oven, and the second online eddy current measuring device. The thin-film solar module is inspected by an online inspection camera after and / or before processing in the curing oven. The first online eddy current measuring device is configured to measure the resistivity of the thin-film solar module; The inkjet printer is configured to print G1 grid lines and G2 grid lines on the front electrode layer of the thin-film solar module. The curing oven is configured to cure the G1 grid lines and G2 grid lines on the front electrode layer of the thin-film solar module; The online inspection camera is configured to detect the linewidth and defects of the G1 and G2 grid lines; The second online eddy current measuring device is configured to measure the resistivity of a thin-film solar module with cured G1 grid lines and G2 grid lines.

8. A system for forming a thin-film solar module, the system comprising an inkjet printer according to any one of claims 1 to 6.

9. The system of claim 8 further includes a substrate receiving device adapted to receive a substrate; one or more absorber layer deposition cluster devices having at least one process chamber adapted to deposit a photovoltaic stack for generating electrical energy on the surface of the substrate; one or more post-electrode layer deposition devices; and one or more photovoltaic stack edge sweeping devices. Solar cell encapsulation equipment; autoclave equipment; automatic junction box connection equipment; And one or more quality inspection devices, said one or more quality inspection devices being suitable for testing and evaluating fully formed thin-film solar modules.

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