An electrode structure suitable for step-by-step printing of high-efficiency solar cells

Abstract

The present invention discloses an electrode structure of a high-efficiency solar cell suitable for step-by-step printing, comprising a main grid and a fine grid, wherein the main grid and the fine grid are connected; wherein the main grid comprises a main grid line in a welding area and a main grid overlap structure; the fine grid comprises a fine grid line and a fine grid overlap structure connecting two adjacent fine grid lines, the distance between two adjacent main grids is the main grid overlap structure spacing, the main grid overlap structure spacing matches the length of the fine grid line, the main grid overlap structure and the fine grid overlap structure intersect and overlap, and both sides of each main grid and both sides of each fine grid line form at least two intersections of intersecting overlap. The present invention can effectively avoid the appearance and EL problems caused by the existing step-by-step printing alignment deviation and the printing problems of parallel overlap at the overlap, and at the same time avoid the component end welding problems caused by the poor overlap of the battery main grid and the fine grid.

Description

Technical Field

[0001] The invention relates to the field of manufacturing solar cells, and in particular to an electrode structure of a high-efficiency solar cell suitable for step-by-step printing. Background Art

[0002] In recent years, the mainstream products of solar cells have transitioned from traditional cells to high-efficiency PERC cells. However, as the conversion efficiency of battery products reaches a bottleneck and the production process continues to mature, solar cells face huge challenges in continuously reducing costs and increasing efficiency.

[0003] Among the non-silicon costs of current solar cell production, silver paste costs are the largest. There are three main methods for printing electrodes: (1) single screen printing technology; (2) secondary printing technology: first print the fine grid, then print the main grid and fine grid together again; (3) step-by-step printing technology: the main grid and fine grid are printed separately.

[0004] like Figure 1 As shown, the printed pattern of single screen printing consists of a main grid 1, a gradient structure 2 between main and fine grids, and a fine grid 3. Due to the limitation of single-printing screens, it is difficult to reduce the cost of solar cells. Moreover, using single screen printing technology, it is difficult to meet the reliability requirements of the cells.

[0005] like Figure 2A , 2B , 2C, the second printing, the first step is to print the fine grid 3 (such as Figure 2A ), the second printing of the main fine grid (such as Figure 2B ), the second printed main grid pattern overlaps with the first printed grid pattern to obtain a second printed pattern with the same pattern (such as Figure 2C ). Secondary printing technology can effectively improve the efficiency of solar cells, but its printing requires precise alignment, and problems such as printing yield, printing reliability and printing unit consumption cannot be effectively solved, making mass production difficult.

[0006] like Figure 3A , 3B As shown in 3C, the step-by-step printing adopts the method of printing the main grid and the fine grid separately. In the first step, the main grid pattern with the main grid 1 and the main fine grid gradient structure 2 is printed (as shown in FIG. Figure 3A ); then print a fine grid pattern with a fine grid 3 and a hollowed-out main grid position (such as Figure 3B ), thereby forming a front grid line consistent with a single printing pattern (such as Figure 3C ). Step-by-step printing technology can effectively improve the efficiency of solar cells and reduce production costs. However, the current step-by-step printing design still has problems such as printing alignment deviation and poor weldability of the battery module end. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide an electrode structure of a high-efficiency solar cell suitable for step-by-step printing, which effectively avoids the appearance and EL problems caused by the existing step-by-step printing alignment deviation and the printing problems of parallel overprinting at the overlap, while avoiding the component end welding problems caused by the poor overlap of the battery main grid and the fine grid.

[0008] In order to solve the above technical problems, the present invention provides an electrode structure of a high-efficiency solar cell suitable for step-by-step printing, comprising a main grid and a fine grid, wherein the main grid and the fine grid are connected;

[0009] Wherein, the main grid includes a welding area main grid line and a main grid overlap structure, the main grid overlap structure is connected to the welding area main grid line, and the width of the main grid overlap structure gradually decreases from the direction close to the welding area main grid line to the direction away from the welding area main grid line;

[0010] The fine gate includes a fine gate line and a fine gate overlap structure connecting two adjacent fine gate lines, one end of the fine gate line is connected to the fine gate overlap structure to form a closed structure, and the other end is connected to the fine gate overlap structure to form a closed structure or an open structure;

[0011] The distance between two adjacent main grids is the main grid overlap structure spacing, the main grid overlap structure spacing matches the length of the fine grid line, the main grid overlap structure and the fine grid overlap structure intersect and overlap, and both sides of each main grid and both sides of each fine grid line form at least two intersecting and overlapping intersections.

[0012] As an improvement of the above solution, the main grid is formed by non-burn-through silver paste printing, and the fine grid is formed by burn-through silver paste printing.

[0013] As an improvement of the above scheme, the non-burn-through silver paste is composed of silver powder, silver-coated copper powder, glass powder, additives and organic carriers;

[0014] The burn-through silver paste consists of silver powder, glass powder and an organic carrier.

[0015] As an improvement of the above scheme, the non-burn-through silver paste is composed of 55-80% silver powder, 15-40% silver-coated copper powder, 1-3% glass powder, 1-3% additives and 1-3% organic carrier;

[0016] The burn-through silver paste is composed of 94-98% silver powder, 1-3% glass powder and 1-3% organic carrier.

[0017] As an improvement of the above solution, the main grid overlap structure is triangular, trapezoidal, semicircular or semi-elliptical;

[0018] The fine grid overlapping structure is in the shape of a straight line, a V shape, a U shape, a semicircle or a semi-ellipse.

[0019] As an improvement of the above scheme, the main grid overlap structure is triangular, the fine grid overlap structure is V-shaped, the main grid overlap structure and the fine grid overlap structure intersect and overlap, and two sides of each main grid and both sides of each fine grid line form two intersecting and overlapping intersections.

[0020] As an improvement of the above solution, the main grid lines and the main grid overlap structures in the welding area are formed by synchronous printing;

[0021] The fine grid lines and the fine grid overlapping structure are formed by synchronous printing.

[0022] As an improvement of the above solution, the number of the main grids is 4 to 20 and they are evenly distributed, the line width of the main grid lines in the welding area is 10 to 1000 μm, and the width of the main grid overlap structure is 10 to 2000 μm;

[0023] The line width of the fine gate lines is 10 to 100 μm, the fine gate spacing is 10 to 2000 μm, and they are evenly distributed; the line width of the fine gate overlap structure connecting two adjacent fine gate lines is 10 to 300 μm;

[0024] As an improvement of the above solution, the main grid overlap structure is set to be hollow;

[0025] Alternatively, the main grid overlapping structure is configured to be solid.

[0026] The implementation of the present invention has the following beneficial effects:

[0027] The main grid pattern of the present invention includes a main grid line in a welding area and a main grid overlap structure, and the fine grid includes a fine grid line and a fine grid overlap structure connecting two adjacent fine grid lines. By matching the main grid line width in the welding area, the main grid overlap structure spacing and the fine grid line length, two adjacent fine grid lines can be overlapped with the main grid overlap structure from both sides to form at least two intersections, so that at least two intersections are formed on both sides of each main grid and on both sides of each fine grid line. Compared with the existing main grid gradient and fine grid single-point overlap scheme, the present invention has a higher tolerance rate for step-by-step printing alignment error accuracy and better overlap reliability, which can effectively reduce problems such as poor appearance and EL caused by step-by-step printing overlap offset.

[0028] The present invention adopts a main grid paste to print the main grid overlap structure, which can effectively prevent the fine grid from breaking and affecting the current transmission. The overlap part is far away from the main grid welding area, which can avoid the overlap from affecting the welding performance of the component end. In addition, the main grid uses a non-burn-through silver paste with good weldability, high adhesion and low cost. While ensuring the reliability of solar cell welding, it can avoid the damage of the passivation film in the main grid area, and can effectively improve the open circuit voltage of the solar cell, thereby improving the conversion efficiency; the fine grid uses a burn-through silver paste with strong printability and good shaping. While ensuring contact with the front of the battery cell, it can reduce the transmission current loss and the front shading loss, effectively improve the short-circuit current and fill factor of the solar cell, thereby improving the conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the effect diagram of the grid line obtained by the existing single screen printing;

[0030] Figure 2A It is a schematic diagram of fine grid printing in the existing secondary printing process;

[0031] Figure 2B It is a schematic diagram of printing the main fine grid in the existing secondary printing process;

[0032] Figure 2C This is the effect diagram of the existing secondary printing to obtain the grid line;

[0033] Figure 3A It is a schematic diagram of main grid printing in the existing step-by-step printing process;

[0034] Figure 3B It is a schematic diagram of fine grid printing in the existing step-by-step printing process;

[0035] Figure 3C It is the effect diagram of the existing step-by-step printing to obtain the grid line;

[0036] Figure 4A It is a structural schematic diagram of the main grid of the present invention;

[0037] Figure 4B is a schematic diagram of the structure of the fine grid of the present invention;

[0038] Figure 4C It is a structural schematic diagram of the electrode structure of the present invention;

[0039] Figure 5 yes Figure 4C A partial enlarged view of the portion A shown;

[0040] Figure 6 It is another structural schematic diagram of the main grid of the present invention. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below.

[0042] The present invention provides an electrode structure of a high-efficiency solar cell suitable for step-by-step printing, comprising a main grid 1 and a fine grid 3, wherein the main grid 1 and the fine grid 3 are connected, preferably vertically connected, wherein:

[0043] like Figure 4A As shown, the busbar 1 includes a welding area busbar line 11 and a busbar lap structure 12 , and the busbar lap structure 12 is connected to the welding area busbar line 11 .

[0044] The width a of the main grid overlap structure 12 gradually decreases from the direction close to the welding area main grid line 11 to the direction far away from the welding area main grid line 11, which can effectively reduce the amount of main grid slurry used. The overlap part is far away from the main grid welding area, which can avoid the overlap from affecting the welding performance of the component end. Moreover, the present invention uses the main grid slurry to print the main grid overlap structure, which can effectively prevent the thin grid from breaking and affecting the current transmission.

[0045] The interior of the main grid line 11 in the welding area is filled with main grid slurry and can be designed according to specific product requirements, such as hollowing, narrowing of non-welding point areas, and tip or fork structures at both ends of the main grid to optimize string welding stress.

[0046] like Figure 4B As shown, the fine grid 3 includes a fine grid line 31 and a fine grid overlap structure 32 connecting two adjacent fine grid lines 31, and the welding area main grid line 11 and the fine grid line 31 are perpendicular to each other. Figure 4C The effect diagram of the grid lines.

[0047] One end of the fine grid line 31 is connected to the fine grid overlap structure 32 to form a closed structure, and the other end is connected to the fine grid overlap structure 32 to form a closed structure or an open structure. Figure 4B , which includes four parts of fine grids, from left to right, fine grid part I, fine grid part II, fine grid part III, and fine grid part IV, and the hollow part in the middle corresponds to the main grid position. Among them, one end of the fine grid line 31 of the fine grid part I and the fine grid part IV is connected to the fine grid overlap structure 32 to form a closed structure, and the other end is an open structure; both ends of the fine grid line 31 of the fine grid part II and the fine grid part III are connected to the fine grid overlap structure 32 to form a closed structure.

[0048] The distance between two adjacent main grids 1 is the main grid overlap structure spacing b, and the main grid overlap structure spacing b matches the length of the fine grid line 31. The main grid overlap structure 12 and the fine grid overlap structure 32 intersect and overlap, so that the two adjacent fine grid lines can intersect and overlap with the main grid overlap structure from both sides to form at least two intersections, so that both sides of each main grid and both sides of each fine grid line form at least two intersections. Compared with the existing main grid gradient and fine grid single-point overlap scheme, the present invention has a higher tolerance rate for step-by-step printing alignment error accuracy and better overlap reliability, which can effectively reduce problems such as poor appearance and EL caused by step-by-step printing overlap offset.

[0049] Preferably, the number of the main grids 1 is 4 to 20 and they are evenly spaced, the line width of the main grid line 11 in the welding area is 10 to 1000 μm, and the width of the main grid overlap structure 12 is 10 to 2000 μm; the line width of the fine grid line 31 is 10 to 100 μm, the fine grid spacing is 10 to 2000 μm, and they are evenly spaced; the line width of the fine grid overlap structure 32 connecting two adjacent fine grid lines 31 is 10 to 300 μm;

[0050] There are many embodiments of the shapes of the main grid overlap structure 12 and the fine grid overlap structure 32. The main grid overlap structure 12 is preferably a triangle, a trapezoid, a semicircle or a semi-ellipse; the fine grid overlap structure 32 is preferably a straight line, a V-shape, a U-shape, a groove shape, a semicircle or a semi-ellipse, but is not limited thereto. More preferably, the main grid overlap structure 12 is preferably an isosceles triangle, an isosceles trapezoid, an arc, a semicircle or a semi-ellipse; the fine grid overlap structure 32 is preferably a straight line, a V-shape or an isosceles groove shape. More preferably, the main grid overlap structure 12 is a triangle, and the fine grid overlap structure 32 is a V-shape. The main grid overlap structure 12 and the fine grid overlap structure 32 intersect and overlap, so that two adjacent fine grid lines can intersect and overlap with the main grid overlap structure from both sides at the same time to form at least two intersections, so that two sides of each main grid and both sides of each fine grid line form two intersections of overlapping, achieving better overlap reliability.

[0051] It should be noted that Figure 4A , Figure 4B , Figure 4C In the embodiment shown, the main grid overlap structure 12 is triangular, and the fine grid overlap structure 32 is V-shaped.

[0052] Among them, the base length of the isosceles triangle main grid overlap structure ranges from 10 to 2000μm, and the vertex angle ranges from 20 to 160°; the base length of the isosceles trapezoidal main grid overlap structure ranges from 10 to 2000μm, and the angle between the base and the waist ranges from 20 to 90°; the diameter of the semicircular main grid overlap structure ranges from 10 to 2000μm; the intersection length of the semi-elliptical main grid overlap structure and the welding area main grid line 11 ranges from 10 to 2000μm.

[0053] The length of the I-shaped fine grid overlap structure 32 is the fine grid spacing; the angle range of the V-shaped fine grid overlap structure 32 is 20 to 160°; the length of the bottom side of the isosceles groove-shaped fine grid overlap structure 32 is 10 to 2000 μm, and the angle between the bottom side and the waist is 90 to 160°; the diameter of the semicircular fine grid overlap structure 32 is 10 to 2000 μm; the length of the intersection of the semi-elliptical fine grid overlap structure 32 and the fine grid line is 10 to 2000 μm;

[0054] like Figure 5 As shown, the main grid overlap structure 12 is preferably set to be hollow, and no slurry is filled in its pattern, which can effectively reduce the amount of main grid slurry used. Moreover, the intersection of the hollow main grid overlap structure 12 and the fine grid overlap structure 32 will also form two intersection points, further ensuring the reliability of the overlap.

[0055] like Figure 6 As shown, the present invention provides another embodiment of the main grid, which is Figure 4A The main grid shown is different in that the main grid overlap structure 12 is set to be solid, and the pattern thereof is filled with slurry.

[0056] The main grid lines and the main grid overlapping structures in the welding area are formed by synchronous printing, and the fine grid lines and the fine grid overlapping structures are formed by synchronous printing, which can simplify the printing steps.

[0057] The main grid uses a non-burn-through silver paste with good weldability, high adhesion and low cost. While ensuring the reliability of solar cell welding, it can avoid damage to the passivation film in the main grid area, and can effectively increase the open circuit voltage of the solar cell, thereby improving the conversion efficiency; the fine grid uses a burn-through silver paste with strong printability and good shaping. While ensuring contact with the front of the battery cell, it can reduce transmission current loss and front shading loss, effectively improve the short-circuit current and fill factor of the solar cell, thereby improving the conversion efficiency.

[0058] Specifically, the non-burn-through silver paste is composed of silver powder, silver-coated copper powder, glass powder, additives and organic carriers. The non-burn-through silver paste is used for printing the main grid, which can only realize the function of current transmission without destroying the passivation dielectric film under the main grid, avoiding unnecessary recombination and improving the open circuit voltage of the battery. At the same time, since it is printed separately from the sub-grid, there is no need to consider the height of the sub-grid, and more optimization can be done on the screen, reducing the amount of slurry used, improving the reliability of string welding, thereby reducing the manufacturing cost of crystalline silicon solar cells and improving the reliability of solar cells. The amount of each component of the non-burn-through silver paste can be designed according to actual conditions. Preferably, the non-burn-through silver paste is composed of 55-80% silver powder, 15-40% silver-coated copper powder, 1-3% glass powder, 1-3% additives and 1-3% organic carriers.

[0059] The burn-through silver paste is composed of silver powder, glass powder and an organic carrier. Traditional single-printing pastes all use burn-through pastes, which can penetrate the passivation anti-reflection film to form contact with the front of the solar cell to derive current, while maintaining a good printing line shape and taking into account good printing reliability. The step-by-step printing fine grid paste of the present invention uses a burn-through silver paste that can optimize the printing line shape and contact performance, and is used in combination with a non-burn-through main grid to achieve the best effect. The amount of each component of the burn-through silver paste can be designed according to actual conditions. Preferably, the burn-through silver paste is composed of 94-98% silver powder, 1-3% glass powder and 1-3% organic carrier.

[0060] The present invention is further described below with specific embodiments

[0061] Example 1

[0062] Uses a battery with a size of 156.75*156.75mm;

[0063] On the front of the battery, the busbar 1 is first printed according to the busbar pattern. The busbar 1 includes a busbar line 11 in the welding area and a busbar overlap structure 12. The width of the busbar line 11 in the welding area is 700 μm. The busbar overlap structure 12 is an isosceles triangle with a side length of 713.5 μm and a vertex angle of 60°. The paste for printing the busbar adopts a non-burn-through silver paste, and the screen is a 325-mesh screen printing screen.

[0064] Then, a fine grid 3 is printed according to the fine grid pattern. The fine grid 3 includes a fine grid line 31 and a fine grid overlap structure 32 connecting two adjacent fine grid lines 31. The width of the fine grid line 31 is 30 μm. The fine grid overlap structure 32 is V-shaped. The line width of the fine grid overlap structure is 100 μm. The paste for printing the fine grid adopts a burn-through type silver paste.

[0065] The comprehensive silver consumption of the printed front electrode in Example 1 is 11 mg lower than that of single printing, and the average conversion efficiency is increased by 0.124%, which is mainly reflected in the open circuit voltage increased by 2.5 mV and the short circuit current increased by 38 mA; the average main grid tension of the step-printed battery is 1 to 2 N higher than that of the traditional single-printed main grid tension.

[0066] Example 2

[0067] Uses a battery with a size of 158.75*158.75mm;

[0068] On the front of the battery, the busbar 1 is first printed according to the busbar pattern. The busbar 1 includes a busbar line 11 in the welding area and a busbar overlap structure 12. The width of the busbar line 11 in the welding area is 700 μm. The busbar overlap structure 12 is an isosceles triangle with a side length of 722.7 μm and a vertex angle of 60°. The paste for printing the busbar adopts a non-burn-through silver paste, and the screen is a 325-mesh screen printing screen.

[0069] Then, a fine grid 3 is printed according to the fine grid pattern, wherein the fine grid 3 comprises a fine grid line 31 and a fine grid overlap structure 32 connecting two adjacent fine grid lines 31, wherein the width of the fine grid line 31 is 30 μm, the fine grid overlap structure 32 is in a groove shape, the length of the top edge is 481.8 μm, the angle between the top edge and the waist edge is 120°, and the line width of the fine grid overlap structure is 100 μm; the paste for printing the fine grid adopts a burn-through type silver paste;

[0070] The comprehensive silver consumption of the printed front electrode in Example 2 is 12.3 mg lower than that of single printing, and the average conversion efficiency is increased by 0.132%, which is mainly reflected in the open circuit voltage increased by 2.5 mV and the short circuit current increased by 39 mA; the average main grid tension of the step-printed battery is 1 to 2 N higher than that of the traditional single-printed main grid tension.

[0071] Example 3

[0072] Uses a battery with a size of 161.7*161.7mm;

[0073] On the front side of the battery, a fine grid 3 is first printed according to a fine grid pattern. The fine grid 3 includes a fine grid line 31 and a fine grid overlap structure 32 connecting two adjacent fine grid lines 31. The width of the fine grid line 31 is 30 μm. The fine grid overlap structure 32 is V-shaped. The line width of the fine grid overlap structure is 100 μm. The paste for printing the fine grid is a burn-through silver paste.

[0074] Then, the busbar 1 is printed according to the busbar pattern. The busbar 1 includes a busbar line 11 in the welding area and a busbar overlap structure 12. The width of the busbar line 11 in the welding area is 700 μm. The busbar overlap structure 12 is an isosceles trapezoid. The length of the base of the isosceles trapezoid is 736.2 μm. The angle between the base and the waist is 60°. The paste for printing the busbar adopts a non-burn-through silver paste, and the screen is a 325-mesh screen printing screen.

[0075] The comprehensive silver consumption of the printed front electrode in Example 3 is 13.5 mg lower than that of single printing, and the average conversion efficiency is increased by 0.152%, which is mainly reflected in the open circuit voltage increased by 2.7 mV and the short circuit current increased by 43 mA; the average main grid tension of the step-printed battery is 1 to 2 N higher than that of the traditional single-printed main grid tension.

[0076] Example 4

[0077] Uses a battery with a size of 161.7*161.7mm;

[0078] On the front side of the battery, a fine grid 3 is first printed according to a fine grid pattern. The fine grid 3 includes a fine grid line 31 and a fine grid overlap structure 32 connecting two adjacent fine grid lines 31. The width of the fine grid line 31 is 30 μm. The fine grid overlap structure 32 is in a groove shape, with a top side length of 504 μm, an angle between the top side and the waist side of 120°, and a line width of the fine grid overlap structure of 100 μm. The paste for printing the fine grid adopts a burn-through type silver paste;

[0079] Then, the busbar 1 is printed according to the busbar pattern. The busbar 1 includes a busbar line 11 in the welding area and a busbar overlap structure 12. The width of the busbar line 11 in the welding area is 700 μm. The busbar overlap structure 12 is an isosceles trapezoid. The base length of the isosceles trapezoid is 756 μm. The angle between the base and the waist is 60°. The paste for printing the busbar adopts non-burn-through silver paste, and the screen is a 325-mesh screen printing screen.

[0080] The comprehensive silver consumption of the printed front electrode in Example 4 is 14.7 mg lower than that of single printing, and the average conversion efficiency is increased by 0.165%, which is mainly reflected in the open circuit voltage increased by 2.8 mV and the short circuit current increased by 48 mA. Because the step-by-step printing uses a high-reliability main grid slurry, the average main grid tension of the step-by-step printed battery is 1 to 2 N higher than that of the traditional single-printing main grid tension.

[0081] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. An electrode structure for a high-efficiency solar cell suitable for step-by-step printing, characterized in that: It includes a main grid and a fine grid, wherein the main grid and the fine grid are connected; Wherein, the main grid includes a welding area main grid line and a main grid overlap structure, the main grid overlap structure is connected to the welding area main grid line, and the width of the main grid overlap structure gradually decreases from the direction close to the welding area main grid line to the direction away from the welding area main grid line; The fine gate includes a fine gate line and a fine gate overlap structure connecting two adjacent fine gate lines, one end of the fine gate line is connected to the fine gate overlap structure to form a closed structure, and the other end is connected to the fine gate overlap structure to form a closed structure or an open structure; The distance between two adjacent main grids is the main grid overlap structure spacing, the main grid overlap structure spacing matches the length of the fine grid line, the main grid overlap structure and the fine grid overlap structure intersect and overlap, and both sides of each main grid and both sides of each fine grid line form at least two intersection points of intersection and overlap; The main grid overlap structure is an isosceles triangle, an isosceles trapezoid, an arc, a semicircle or a semi-ellipse; The length of the base of the isosceles triangle main grid overlap structure ranges from 10 to 2000 μm, and the vertex angle ranges from 20 to 160°; the length of the base of the isosceles trapezoidal main grid overlap structure ranges from 10 to 2000 μm, and the angle between the base and the waist ranges from 20 to 90°; the diameter of the semicircular main grid overlap structure ranges from 10 to 2000 μm; the length of the intersection of the semi-elliptical main grid overlap structure and the welding area main grid line 11 ranges from 10 to 2000 μm; The fine grid overlap structure is V-shaped or isosceles groove-shaped; The included angle of the V-shaped fine grid overlap structure is in the range of 20 to 160°; the length of the bottom side of the isosceles groove-shaped fine grid overlap structure is in the range of 10 to 2000 μm, and the included angle between the bottom side and the waist is in the range of 90 to 160°; The width of the main grid overlap structure is 10 to 2000 μm; The line width of the fine gate overlap structure connecting two adjacent fine gate lines is 10 to 300 μm.

2. The electrode structure of a high-efficiency solar cell suitable for step-by-step printing as claimed in claim 1, characterized in that: The main grid is formed by non-burn-through silver paste printing, and the fine grid is formed by burn-through silver paste printing.

3. The electrode structure of a high-efficiency solar cell suitable for step-by-step printing as claimed in claim 2, characterized in that: The non-burn-through silver paste is composed of silver powder, silver-coated copper powder, glass powder, additives and organic carriers; The burn-through silver paste consists of silver powder, glass powder and an organic carrier.

4. The electrode structure of a high-efficiency solar cell suitable for step-by-step printing as claimed in claim 3, characterized in that: The non-burn-through silver paste is composed of 55-80% silver powder, 15-40% silver-coated copper powder, 1-3% glass powder, 1-3% additives and 1-3% organic carrier; The burn-through silver paste is composed of 94-98% silver powder, 1-3% glass powder and 1-3% organic carrier.

5. The electrode structure of a high-efficiency solar cell suitable for step-by-step printing as claimed in claim 1, characterized in that: The main grid overlap structure is triangular, the fine grid overlap structure is V-shaped, the main grid overlap structure and the fine grid overlap structure intersect and overlap, and two sides of each main grid and two sides of each fine grid line form two intersecting and overlapping intersections.

6. The electrode structure of a high-efficiency solar cell suitable for step-by-step printing as claimed in claim 1, characterized in that: The main grid lines and the main grid overlap structures in the welding area are formed by synchronous printing; The fine grid lines and the fine grid overlapping structure are formed by synchronous printing.

7. The electrode structure of a high-efficiency solar cell suitable for step-by-step printing as claimed in claim 1, characterized in that: The number of the main grid lines is 4 to 20 and they are evenly distributed. The line width of the main grid lines in the welding area is 10 to 1000 μm.

8. The electrode structure of a high-efficiency solar cell suitable for step-by-step printing as claimed in claim 1, characterized in that: The line width of the fine gate lines is 10-100 μm, the fine gate spacing is 10-2000 μm, and they are equidistantly distributed.

9. The electrode structure of a high-efficiency solar cell suitable for step-by-step printing as claimed in claim 1, characterized in that: The main grid overlap structure is configured to be hollow; Alternatively, the main grid overlapping structure is configured to be solid.

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