A multi-busbar solar cell, interconnection structure and printing method thereof

Abstract

The present invention discloses a multi-busbar solar cell, an interconnection structure and a printing method thereof, belonging to the field of solar cell manufacturing technology, comprising a front electrode and a back electrode, the front electrode comprising a plurality of fine grid lines and a busbar line, the number of the busbar lines being no less than 9, the fine grid lines being perpendicular to the busbar lines, the two ends of the busbar lines extending outwardly being connected with end welding tabs, the end welding tabs provided at the two ends of the busbar lines forming end welding areas, and no welding spots being provided at the intersections of the busbar lines and the fine grid lines. The present invention adopts a design of connecting welding tabs at the two ends and the middle of the busbar lines, eliminating the original welding spot structure on the busbar lines, thereby eliminating the component end MBB automated welding wire welding process, saving steps, eliminating the use of welding wire for interconnection at the component manufacturing end, thereby improving alignment accuracy, avoiding white spot or cold solder joint problems, and providing welding areas only at the two ends and the middle of the multi-busbar solar cell, saving conductive silver paste, reducing the shading area, and improving conversion efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cell manufacturing, and in particular relates to a multi-busbar solar cell, an interconnection structure and a printing method thereof. Background Art

[0002] Metallization is a key step in the solar cell production process. Photogenerated carriers must pass through the conductive electrodes formed by metallization to be effectively collected. The solar cell metallization process has the following direct effects on the optical and electrical performance of the cell and module:

[0003] (1) Optical performance impact: The cell metallization covers the light-receiving surface of the cell. This area will cause a certain area of ​​light shielding and reflection of the incident light radiation energy to the cell, directly affecting the short-circuit current of the solar cell and module;

[0004] (2) Influence of electrical performance. In order to form good contact and take into account solderability, crystalline silicon solar cells are generally printed with silver paste conductive electrodes on the front and silver-aluminum paste conductive electrodes on the back. Cell metallization mainly affects electrical performance from the aspects of metal fine grid conduction resistance, metal-semiconductor contact resistance and diode resistance. The component end is mainly affected by the effective series resistance between the soldering ribbon and the silver paste conductive electrodes on the front and silver-aluminum paste conductive electrodes on the back.

[0005] To improve cell efficiency and module power, optimized cell metallization electrodes should minimize shading and resistive losses, requiring optimal optical and electrical matching of electrode designs. Multi-busbar (MBB) technology is one effective approach. As the number of busbars increases, the distance the secondary grid must conduct current decreases, and the corresponding power loss is inversely proportional to the square of the transmission distance. Therefore, cell efficiency and module power loss decrease with increasing busbar count. Furthermore, to balance optical design and reduce shading on the front of the solar cell, the busbar width of the MBB is further reduced, and the busbar shape is evolving from a straight-through design to a bamboo-jointed or even node-like design. By combining this reduction in busbar width with a matching number of fine grids, multi-busbar technology can significantly reduce silver paste consumption while maintaining or increasing module power. By matching the MBB design with improved screen, paste, and printing parameters, the company has achieved a cell conversion efficiency improvement of +0.08%-0.15%, while reducing the wet weight of the positive electrode busbar and secondary grid by over 25% compared to the target wet weight of conventional cells. Summary of the Invention

[0006] The present invention aims to solve the problems of poor welding reliability, low conversion efficiency, high shading area and high cost caused by the busbar structure of conventional technology. In multi-busbar high-efficiency solar cells, round welding wires are used at the welding ends of the modules, which makes alignment difficult and leads to white spots or low welding tension. By designing the cell pattern in the metallization process at the cell manufacturing end and matching it with an appropriate module string welding connection method, the use of welding wire for interconnection at the module manufacturing end is eliminated, thereby improving alignment accuracy, avoiding white spots / cold solder joints, and reducing the introduction of expensive full-set automated alignment equipment and facilities to a certain extent. A multi-busbar solar cell, an interconnection structure and a printing method thereof are provided. The multi-busbar busbars are produced by screen printing thick film conductive adhesive, eliminating all node / pad design, eliminating solder joints at the intersection of the positive electrode busbar and the auxiliary busbar, and retaining only XX to XX mm welding areas at the ends of the busbars. This minimizes the gridline shading area, reduces Ag consumption, and reduces solder joint shading loss. Furthermore, the back surface retains only XX to XX mm welding areas at the ends, which also reduces back surface silver paste consumption. Since the back-end components are serially soldered, wire alignment is eliminated, saving on solder ribbon material and facilitating handling. This also eliminates the risk of misalignment of the entire thin, circular ribbon, which can lead to false solder joints and light shielding loss. The busbar can also be designed in two sections, compatible with half-cell designs. A small, wider busbar section (XX to XX mm) is designed at the end of each section to facilitate cell welding.

[0007] The technical solution adopted in the present invention is as follows:

[0008] A multi-busbar solar cell interconnection structure includes a front electrode and a back electrode. The front electrode includes multiple fine grid lines and bus bars. The number of the bus bars is no less than 9. The fine grid lines are perpendicular to the bus bars. Both ends of the bus bars extend outward and are connected to end welding plates. The end welding plates provided at both ends of the bus bars form end welding areas. No welding points are provided at the intersections of the bus bars and the fine grid lines.

[0009] In a further preferred embodiment of the present invention, an inner welding piece is extended upwardly from the middle portion of the main grid line and connected thereto, and the inner welding piece provided at the middle portion of the main grid line forms an inner welding area.

[0010] In a further preferred embodiment of the present invention, the width of the main grid line is 30 um to 300 um, and the thickness of the main grid line is 20-200 um.

[0011] In a further preferred embodiment of the present invention, the width of the thin gate lines is 20-50 um, and the thickness of the thin gate lines is 20-80 um.

[0012] In a further preferred embodiment of the present invention, four positioning dots are provided around the front electrode, and the positioning dots are used for positioning and alignment of screen printing.

[0013] In a further preferred embodiment of the present invention, the screen printing paste is silver paste, copper paste or a combination thereof.

[0014] A multi-busbar solar cell, the structure of the cell comprising the multi-busbar interconnection structure described in any one of the above embodiments.

[0015] A method for printing a multi-busbar solar cell interconnection structure, wherein the multi-busbar lines are produced by screen printing a thick film conductive adhesive, comprising the following steps:

[0016] Step 1: Theoretically calculate the gate line body resistance, the contact resistance between the fine gate line and silicon, the silicon wafer body resistance, etc., and design the optimal number of fine gate lines, the optimal main gate line width and the optimal fine gate line width;

[0017] Step 2: Design the total area of ​​the positive electrode pattern;

[0018] Step 3: Using a distributed printing process, the main grid lines and fine grid lines are printed separately to obtain the grid line pattern with the required width and height to form the front electrode pattern;

[0019] Step 4: Successfully complete the series contact between the two pieces at the component end, and interconnect them through the bent welding pieces and the welding areas at both ends of the positive electrode main grid and the back electrode main grid.

[0020] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0021] 1. Compared to existing MBB cell conductive electrode designs, this invention utilizes welding pads at both ends and in the middle of the busbar, eliminating the existing solder joints on the busbars. This eliminates the automated wire welding process for the MBB modules, saving steps and eliminating the need for wire interconnection at the module manufacturing end. This improves alignment accuracy, avoids white spots or cold solder joints, and reduces the need for expensive, fully automated alignment equipment. Welding zones are provided only at the ends and in the middle of the multi-busbar cell, conserving conductive silver paste and reducing the shading area, further improving conversion efficiency. Compared to existing technologies, this eliminates the solder joints on the busbars and reduces the width of the busbars and thin lines, reducing the shading area and thereby increasing photoelectric conversion efficiency. The multi-busbars are produced using screen printing, which reduces paste consumption and significantly reduces costs.

[0022] 2. The present invention sets four positioning dots around the front electrode to ensure accurate printing contact between the main grid line and the fine grid line to avoid deformation and displacement.

[0023] 3. The present invention is compatible with the equipment involved in traditional crystalline silicon cells. There is no need to introduce a high-cost full set of automated alignment equipment. It only requires less manpower and material costs to complete the packaging of MBB cells and components, with low production costs and good industrial application prospects.

[0024] 4. Compared with the existing MBB battery conductive electrode design, the present invention adopts a design with welding plates at both ends of the main grid, eliminating the need for welding ribbons and their complex and precise alignment process, and directly connects the battery cell current in series through the welding plates at both ends. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0026] Figure 1 is a schematic diagram of the front electrode structure of the present invention;

[0027] Figure 2 is a schematic diagram of another front electrode structure of the present invention;

[0028] Figure 3 is a schematic diagram of the main grid line of the front electrode of the present invention;

[0029] Figure 4 It is a schematic diagram of the fine grid lines of the front motor of the present invention.

[0030] Reference numerals: 1-main grid line, 2-fine grid line, 3-end welding piece, 4-inner welding piece, 5-positioning dot. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. That is, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. All features disclosed in this specification, or all steps in the disclosed methods or processes, except for mutually exclusive features and / or steps, can be combined in any manner.

[0032] It should be noted that the terms "length", "width", "height", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0033] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely intended to represent selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0034] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0035] The following combination Figure 1-4 The present invention is described in detail.

[0036] Implementation Case 1: A multi-busbar solar cell interconnection structure includes a front electrode and a back electrode. The front electrode includes a plurality of fine grid lines 2 and a busbar line 1. The number of the busbar lines 1 is not less than 9. Figure 1 As shown, there are 12 main grid lines 1, which are vertically arranged on the silicon wafer. Several fine grid lines 2 are evenly distributed on the main grid lines 1. The fine grid lines 2 are perpendicular to the main grid lines 1, and the two ends of the main grid lines 1 extend outward and are connected with end welding plates 3. The end welding plates 3 set at both ends of the main grid lines 1 form end welding areas. There are no solder joints at the intersections of the main grid lines 1 and the fine grid lines 2. Canceling the structure of setting solder joints can reduce the shading area and improve the photoelectric conversion efficiency. At the same time, the solder joint design of the prior art is cancelled, the limitations of conventional thinking are overcome, and the process of solder joint welding equipment is cancelled (welding equipment, such as a set of foreign MBB automatic wire welding equipment, which costs tens of millions or millions, greatly reduces costs), shortens the process flow, and improves the film production rate. Four positioning dots 5 are set around the front electrode. The positioning dots 5 are used for positioning and alignment of screen printing. The screen printing paste is silver paste, copper paste or a combination thereof to ensure precise printing contact between the main grid lines 1 and the fine grid lines 2 to avoid deformation and displacement.

[0037] The width of the main grid line 1 is 30um~300um, the thickness of the main grid line 1 is 20-200um, the width of the fine grid line 2 is 20~50um, and the thickness of the fine grid line 2 is 20-80um. Compared with traditional technology, the width of the main grid line 1 is reduced, the shading area is further reduced, and the silver paste consumption is further reduced.

[0038] Implementation Case 2: A multi-busbar solar cell interconnection structure includes a front electrode and a back electrode. The front electrode includes a plurality of fine grid lines 2 and a busbar line 1. The number of the busbar lines 1 is not less than 9. Figure 2 As shown, an example is shown of 12 main grid lines 1, which are vertically arranged on a silicon wafer. Several fine grid lines 2 are evenly distributed on the main grid lines 1, and the fine grid lines 2 are perpendicular to the main grid lines 1. The two ends of the main grid lines 1 extend outwards and are connected with end welding pieces 3. The end welding pieces 3 arranged at the two ends of the main grid lines 1 form an end welding area. The middle of the main grid lines 1 extends upwards and is connected with an inner welding piece 4. The inner welding piece 4 arranged in the middle of the main grid lines 1 forms an inner welding area. There is no welding point at the intersection of the main grid lines 1 and the fine grid lines 2. The structure of canceling the setting of the welding point can reduce the shading area and improve the quality of the display. High photoelectric conversion efficiency, while eliminating the solder joint design of the existing technology, overcoming the limitations of conventional thinking, eliminating the process of solder joint welding equipment (eliminating welding equipment, for example, a set of foreign MBB automatic wire welding equipment costs tens of millions or millions, which greatly reduces costs), shortening the process flow, and improving the film production rate. Four positioning dots 5 are set around the front electrode. The positioning dots 5 are used for positioning and alignment of screen printing. The screen printing slurry is silver paste, copper paste or a combination thereof to ensure precise printing contact between the main grid line 1 and the fine grid line 2 to avoid deformation and displacement.

[0039] The width of the main grid line 1 is 100um~300um, the thickness of the main grid line 1 is 20-200um, the width of the fine grid line 2 is 20~50um, and the thickness of the fine grid line 2 is 20-60um. Compared with traditional technology, the width of the main grid line 1 is reduced, the shading area is further reduced, and the silver paste consumption is further reduced.

[0040] Implementation Case 3: A multi-busbar solar cell includes a front electrode and a back electrode. The front electrode includes a plurality of fine grid lines 2 and a busbar line 1. The number of the busbar lines 1 is not less than 9. Figure 2As shown, an example is shown of 12 main grid lines 1, which are vertically arranged on a silicon wafer. Several fine grid lines 2 are evenly distributed on the main grid lines 1, and the fine grid lines 2 are perpendicular to the main grid lines 1. The two ends of the main grid lines 1 extend outwards and are connected with end welding pieces 3. The end welding pieces 3 arranged at the two ends of the main grid lines 1 form an end welding area. The middle of the main grid lines 1 extends upwards and is connected with an inner welding piece 4. The inner welding piece 4 arranged in the middle of the main grid lines 1 forms an inner welding area. There is no welding point at the intersection of the main grid lines 1 and the fine grid lines 2. The structure of canceling the setting of the welding point can reduce the shading area and improve the quality of the display. High photoelectric conversion efficiency, while eliminating the solder joint design of the existing technology, overcoming the limitations of conventional thinking, eliminating the process of solder joint welding equipment (eliminating welding equipment, for example, a set of foreign MBB automatic wire welding equipment costs tens of millions or millions, which greatly reduces costs), shortening the process flow, and improving the film production rate. Four positioning dots 5 are set around the front electrode. The positioning dots 5 are used for positioning and alignment of screen printing. The screen printing slurry is silver paste, copper paste or a combination thereof to ensure precise printing contact between the main grid line 1 and the fine grid line 2 to avoid deformation and displacement.

[0041] The width of the main grid line 1 is 180um~300um, the thickness of the main grid line 1 is 25-40um, the width of the fine grid line 2 is 30~50um, and the thickness of the fine grid line 2 is 20-45um. Compared with traditional technology, the width of the main grid line 1 is reduced, the shading area is further reduced, the silver paste consumption is further reduced, and the photoelectric conversion efficiency is improved.

[0042] Implementation Case 4: A method for printing a multi-busbar solar cell interconnect structure, wherein the multi-busbar lines are produced by screen printing a thick film conductive adhesive, comprising the following steps:

[0043] Step 1: Theoretically calculate the gate line body resistance, the contact resistance between the fine gate line 2 and silicon, the silicon wafer body resistance, etc., to design the optimal number of fine gate lines 2, the optimal width of the main gate line 1 and the optimal width of the fine gate line 2;

[0044] Step 2: Design the total area of ​​the positive electrode pattern;

[0045] Step 3: Using a distributed printing process, the main grid lines 1 and the fine grid lines 2 are printed separately to obtain a grid line pattern of the required width and height to form a front electrode pattern;

[0046] Step 4: Successfully complete the series contact between the two pieces at the component end, and interconnect them through the bent welding pieces and the welding areas at both ends of the positive electrode main grid and the back electrode main grid.

[0047] The fixed connection, fixed installation or fixed setting method includes existing common technologies, such as bolt fixing, welding, riveting, etc., all of which are for fixing purposes and do not affect the overall effect of the device.

[0048] Although the present invention has been described herein with reference to a number of illustrative embodiments thereof, it will be understood that numerous other modifications and implementations may be devised by those skilled in the art that fall within the scope and spirit of the principles disclosed herein. More specifically, within the scope of the present disclosure and claims, numerous variations and improvements may be made to the components and / or layout of the subject combination arrangement. In addition to variations and improvements made to the components and / or layout, other uses will also be apparent to those skilled in the art.

Claims

1. A multi-busbar solar cell interconnection structure, comprising a front electrode and a back electrode, wherein the front electrode comprises a plurality of fine grid lines (2) and a busbar line (1), characterized in that: The number of the main grid lines (1) is no less than 9, the fine grid lines (2) and the main grid lines (1) are perpendicular to each other, the two ends of the main grid lines (1) extend outwardly and are connected to end welding pieces (3), the end welding pieces (3) provided at the two ends of the main grid lines (1) form end welding areas, and no welding points are provided at the intersections of the main grid lines (1) and the fine grid lines (2).

2. The multi-busbar solar cell interconnection structure according to claim 1, characterized in that: The middle portion of the main grid line (1) extends upwards and is connected to an internal welding piece (4), and the internal welding piece (4) provided in the middle portion of the main grid line (1) forms an internal welding area.

3. The multi-busbar solar cell interconnection structure according to claim 1, characterized in that: The width of the main grid line (1) is 30um to 300um, and the thickness of the main grid line (1) is 20-200um.

4. The multi-busbar solar cell interconnection structure according to claim 1, characterized in that: The width of the fine grid line (2) is 20-50 μm, and the thickness of the fine grid line (2) is 20-80 μm.

5. The multi-busbar solar cell interconnection structure according to claim 1, characterized in that: Four positioning dots (5) are arranged around the front electrode, and the positioning dots (5) are used for positioning and alignment of screen printing.

6. The multi-busbar solar cell interconnection structure according to claim 5, characterized in that: The screen printing paste is silver paste, copper paste or a combination thereof.

7. A multi-busbar solar cell, characterized in that: The structure of the battery includes the multi-busbar solar cell interconnection structure according to any one of claims 1 to 6.

8. A method for printing a multi-busbar solar cell interconnection structure, characterized in that: The multi-busbar grid lines are produced by screen printing thick film conductive adhesive, which includes the following steps: Step 1: Theoretically calculate the gate line body resistance, the contact resistance between the fine gate line (2) and silicon, the silicon wafer body resistance, etc., and design the optimal number of fine gate lines (2), the optimal width of the main gate line (1) and the width of the fine gate line (2); Step 2: Design the total area of ​​the positive electrode pattern; Step 3: using a distributed printing process, that is, printing the main grid lines (1) and the fine grid lines (2) separately to obtain a grid line pattern of required width and height to form a front electrode pattern; Step 4: Successfully complete the series contact between the two pieces at the component end, and interconnect them through the bent welding pieces and the welding areas at both ends of the positive electrode main grid and the back electrode main grid.

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