Solar cell sheet, shingle assembly and printing screen

Abstract

The application provides a solar cell, which comprises a front surface provided with at least one main grid line and a plurality of sub-grid lines arranged at intervals and vertically to the main grid line, and is characterized in that further comprising a back surface provided with a plurality of fine grid lines arranged at intervals and in parallel to the sub-grid lines. The application also provides a double-sided shingle module with the cell structure and a printing screen for printing the back surface structure of the cell. The back surface structure of the application replaces the full back surface covering of the existing back surface with aluminum paste with fine grid lines formed by aluminum paste, which can reduce the amount of aluminum paste in the back surface and improve the output power of the cell module, so that the conversion efficiency of the shingle module can reach 24.48% at most, and the optimal interval and line width of the fine grid lines are provided; and the warping degree of the back surface of the cell after sintering can be kept within the range of 1.1-1.3 mm.

Description

Technical Field

[0001] This invention belongs to the field of solar cell shingled module manufacturing technology, and in particular relates to a solar cell, a shingled module, and a printing screen. Background Technology

[0002] Conventional solar cells generate electricity on the front side, with the back side fully covered by aluminum paste. This results in low power generation and high aluminum paste consumption, which also reduces power gain. Especially with the development of large-size silicon wafers and their increasing use in shingled solar modules, the amount of aluminum paste required for full back-side coverage in a single cell further increases, leading to minimal power gain and failing to maximize the conversion efficiency of large-size cells. It also affects the stability of the front-side power output. Furthermore, excessive aluminum paste coverage causes bending and deformation of the cells after sintering, severely impacting cell cutting and slicing, and making them prone to breakage. Summary of the Invention

[0003] This invention provides a solar cell, a shingled module, and a printing screen, particularly suitable for the back surface structure of bifacial solar cells, solving the technical problems of low power, low conversion efficiency, small power enhancement, and easy deformation of solar cells in the prior art.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A solar cell includes a front side having at least one main grid line and a plurality of secondary grid lines arranged at intervals perpendicular to the main grid line, and further includes:

[0006] It has a back field with several fine grid lines arranged parallel to and spaced apart from the sub-grid lines.

[0007] Furthermore, the fine grid lines are uniformly distributed on the back field;

[0008] Preferably, the spacing between adjacent fine grid lines is 0.9-1.1 mm;

[0009] Preferably, the width of the fine grid line is 150-180 μm;

[0010] Preferably, the spacing between adjacent fine grid lines is 1 mm.

[0011] Furthermore, the back field is also provided with at least one back pole slot perpendicular to the fine grid line;

[0012] The back electrode slots are uniformly arranged along the length direction of the back field.

[0013] The back electrode points of all the aforementioned battery cells are placed within the back electrode grooves and are arranged in a single row with staggered spacing along the length of the back electrode grooves.

[0014] Furthermore, the width of the back electrode slot is 4-6 mm;

[0015] Preferably, the number of back electrode slots is 1-5;

[0016] Preferably, the back pole slot is not superimposed on the main grid line.

[0017] Furthermore, several rows of spaced pad slots are provided in the back field along the length direction of the fine grid line;

[0018] Preferably, a set of pad slots is symmetrically provided on both sides of each of the back electrode slots;

[0019] Preferably, the pad points of the battery cell are placed in the pad slots and are configured to correspond one-to-one with the pad slots.

[0020] Furthermore, both the back electrode groove and the pad groove are structures printed with silver paste;

[0021] Both the back electrode point and the pad point are aluminum paste printed structures.

[0022] A shingled module includes several sets of battery strings arranged vertically and connected in a shingled manner using battery cells as described in any of the preceding claims, wherein the number of battery strings is five.

[0023] A printing screen for screen printing the back surface of a battery cell as described in any of the preceding claims, comprising at least a first screen having at least a plurality of fine grid lines arranged parallel to and spaced apart from the subgrid lines.

[0024] Furthermore, the No. 1 network version is also configured with:

[0025] At least one back pole slot perpendicular to the fine grid line; and

[0026] Several rows of spaced pad slots are provided along the length of the fine grid line;

[0027] The back electrode groove is uniformly arranged along the length direction of the first screen plate;

[0028] The back electrode points of all the aforementioned cells are placed within the back electrode groove and are arranged in a single row with staggered spacing along the length of the back electrode groove.

[0029] The fine grid lines are evenly distributed on the No. 1 screen printing plate;

[0030] The spacing between adjacent fine grid lines is 0.9-1.1 mm;

[0031] The width of the fine grid lines is 150-180μm;

[0032] Preferably, the spacing between adjacent fine grid lines is 1 mm.

[0033] The back pole slot is not superimposed on the main grid line;

[0034] The width of the back electrode slot is 4-6mm;

[0035] The number of back electrode slots is 1-5;

[0036] Each of the back electrode slots has a set of pad slots symmetrically arranged on both sides.

[0037] Furthermore, it also includes: a second screen printing plate for printing back electrode points placed inside the back electrode groove and pad points placed inside the pad groove; the outer dimensions of the second screen printing plate and the first screen printing plate are the same as the back electrode dimensions;

[0038] All of the back poles are placed in the back pole slots and are arranged in a single row with staggered spacing along the length of the back pole slots.

[0039] The pad points are placed in the pad slots and are set in a one-to-one correspondence with the pad slots.

[0040] Compared with existing technologies, the solar cell designed in this invention replaces the existing structure of full back-side coverage with aluminum paste with fine grid lines formed by aluminum paste. This reduces the amount of aluminum paste used in the back-side field while increasing the output power of the solar module, enabling the conversion efficiency of shingled modules to reach up to 24.48%. Furthermore, it proposes optimal grid line spacing and line width dimensions. The warpage of the solar cell after back-side field sintering is maintained within the range of 1.1-1.3 mm.

[0041] The present invention also includes a double-sided shingled assembly having the battery cell structure and a printing screen for printing the back field structure of the battery cell. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the back surface structure of a solar cell according to Embodiment 1 of the present invention;

[0043] Figure 2 yes Figure 1 Enlarged view of section A in the middle;

[0044] Figure 3 This is a schematic diagram of the back surface structure of a solar cell according to Embodiment 2 of the present invention;

[0045] Figure 4 This is a schematic diagram of the back surface structure of a solar cell according to Embodiment 3 of the present invention;

[0046] Figure 5This is a schematic diagram of the circuit structure of a shingled assembly according to an embodiment of the present invention;

[0047] Figure 6 This is a schematic diagram of the structure of a No. 1 screen version according to an embodiment of the present invention;

[0048] Figure 7 This is a schematic diagram of the structure of the second screen version according to an embodiment of the present invention.

[0049] In the picture:

[0050] 10. Back field; 11. Fine grid line; 12. Back electrode slot.

[0051] 13. Pad slot 14. Back pole 15. Pad dot

[0052] 16. Positioning point; 17. Positioning slot; 20. No. 1 mesh plate.

[0053] 21, mark point 30, second-generation version Detailed Implementation

[0054] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0055] This embodiment proposes a solar cell, such as Figure 1 As shown, a solar cell includes a front side having at least one main grid line and several secondary grid lines arranged at intervals perpendicular to the main grid line, and a back surface 10 having several fine grid lines 11 arranged parallel to and at intervals with the secondary grid lines. The main grid line and secondary grid lines on the front side are formed of silver paste. The main grid line primarily collects and conducts current from the secondary grid lines. The fine grid lines 11 in the back surface 10, formed of aluminum paste, are used for substrate charge collection and as a reflective field to reflect electrons, increasing cell conversion efficiency. However, excessive aluminum paste area can affect current flow, increase resistance, and not only reduce the power gain of the front side of the cell but also cause severe bending and warpage during subsequent sintering. Therefore, replacing the existing full back-side aluminum paste coverage structure with an aluminum paste grid line structure reduces the resistance of electron load, thereby improving the conversion efficiency on the front side of the cell. Simultaneously, a smaller number of uniformly arranged fine grid lines 11 facilitates sintering solidification, reducing stress concentration caused by aluminum paste agglomeration. Several parallel fine grid lines 11 act as several separately arranged stress relief grooves, rapidly releasing stress and reducing stress concentration after sintering, thus minimizing deformation and ensuring stable and qualified cell warpage. This also reduces the amount of aluminum paste used, lowering production costs. Furthermore, the fine grid lines 11 arranged parallel to the sub-grid lines facilitate current transmission, preventing current disconnection between stacked cells.

[0056] Furthermore, at least one back electrode groove 12 perpendicular to the fine grid line 11 and used to set the back electrode 14 is also configured in the back field 10, and the back electrode groove 12 is uniformly arranged along the length direction of the back field 10. The back electrode 14 is a structure formed by silver paste, and the back electrode 14 of all cells is wrapped within the back electrode groove 12 formed by aluminum paste, and is arranged in a single row with staggered arrangement along the length direction of the back electrode groove 12, as shown in Figure 2. The back electrode 14 is used to collect the current from the fine grid line 11, and transmit and collect it through conductive adhesive or welding rods welded to the back electrode 14, and then conduct the current through the welding rods. Like the front field, the back field 10 can also collect current-carrying electrons and collect them together to conduct the current, thereby increasing the overall power of the cell, while not reducing the power of the front field of the cell due to the increase in series resistance.

[0057] Furthermore, the fine grid lines 11 are uniformly distributed on the back surface 10. Preferably, based on the limitation of the cell resistance, the conversion efficiency of the obtained cell is maximized when the line spacing between adjacent fine grid lines 11 is 0.9-1.1 mm; if the line spacing between adjacent fine grid lines 11 is too wide, the number of fine grid lines 11 per unit area decreases, the transmission resistance increases, and the warpage decreases.

[0058] For solar cells with different grid line spacings 11 and back field 10, high-temperature sintering was performed using the same process. The warpage of the resulting solar cells is shown in Table 1. As can be seen from Table 1, the warpage gradually decreases with the increase of the grid line spacing 11, indicating a gradual reduction in deformation. Compared to the back field 10 structure with full back-side aluminum paste coverage, the structure proposed in this embodiment not only reduces the amount of aluminum paste used but also minimizes solar cell deformation, thereby obtaining solar cells with stable and qualified warpage of this back field 10 structure.

[0059] Table 1 shows the back field of different grid spacings and the resulting cell warpage.

[0060]

[0061] During processing, the laser grooving line must match the width of the aluminum paste fine grid line 11. Preferably, the width of the fine grid line 11 is 150-180 μm. This is because if the width of the fine grid line 11 is less than 150 μm, its transmission resistance is too high, which is not conducive to the output of battery power, and the precision of current lasers is not yet sufficient; if the width of the fine grid line 11 is greater than 180 μm, the production cost is too high and the production efficiency is too low.

[0062] Furthermore, such as Figure 2As shown, the width W1 of the back electrode groove 12 is 4-6mm. Preferably, the number of back electrode grooves 12 is 1-5. The number of back electrode grooves 12 is the number of back electrode points 14 arranged, that is, how many rows of back electrode points 14 are in the back field 10 of each solar cell. If the number of back electrode grooves 12 is greater than 5, the number of solar cells obtained after cutting the solar cells will be large, but their width will be narrow, resulting in an excessively high stacking height of the shingled module, which is not suitable for the power station. Further, the number of back electrode grooves 12 is 1-5, preferably 3, and their distribution structure is as follows: Figure 1 , Figure 3 and Figure 4 As shown, when the number of back pole slots 12 is 3, the structure is as follows: Figure 1 As shown; when the number of back pole slots 12 is 1, the structure is as follows. Figure 3 As shown; when the number of back pole slots 12 is 5, the structure is as follows. Figure 4 As shown. Furthermore, the back electrode groove 12 is not superimposed on the main grid line on the front side (omitted in the attached diagram), the purpose of which is to ensure that the back electrode groove 12 does not affect the current collection on the main grid line on the front side of the solar cell. Of course, the back electrode groove 12 in the back field 10 can also have other values ​​of structure, which are omitted here, but all are within the scope of protection of this application.

[0063] Furthermore, several rows of spaced and independently arranged pad slots 13 are provided in the back field 10 along the length direction of the fine grid lines 11; that is, three rows of pad slots 13 are provided in the back field 10, and each row has several independently arranged and spaced pad slots 13, and a set of pad slots 13 is symmetrically arranged on both sides of each back electrode slot 12. Preferably, the pad points 15 of the battery cell are placed in the pad slots 13, as shown in the structure. Figure 5 As shown, pad point 15 and pad slot 13 are set in a one-to-one correspondence.

[0064] Preferably, such as Figure 2 As shown, the width W2 of the pad groove 13 is 4-6mm, and its length H is 8-10mm. All pad points 15 are built into the pad groove 13 and are encased in the aluminum paste in the pad groove 13.

[0065] In this embodiment, both the back electrode groove 12 and the pad groove 13 are silver paste printed structures; while the back electrode point 14 and the pad point 15 are the same as the fine grid line 11, both being aluminum paste printed structures. There is a certain gap between the outer ring of all back electrode points 14 and the outer edge of the width of the back electrode groove 12, and there is also a certain gap between the outer ring of all pad points 15 and the outer edge of the pad groove 13; that is, the silver paste-formed back electrode points 14 and pad points 15 are respectively wrapped by the aluminum paste-formed back electrode groove 12 and pad groove 13. This structure of the solar cell not only facilitates current collection and extraction, but also ensures that the front power of the solar cell will not decrease due to the increase in series resistance.

[0066] Furthermore, the back field 10 is provided with several positioning points 16 for subsequent equal-division cutting and positioning. The positioning points 16 are respectively arranged along the periphery of the back field 10, and positioning grooves 17 are provided around the positioning points 16 so that the silver paste positioning points 16 are surrounded by the aluminum paste positioning grooves 17. In this embodiment, there are six positioning points 16. Two and one positioning points 16 are respectively provided on both sides from left to right along the length direction of the fine grid line 11; one and two positioning points 16 are respectively provided on both sides from top to bottom along the length direction of the back electrode groove 12. All positioning points 16 are located in the area where the fine grid line 11 is located to avoid affecting the welding of the back electrode point 14 and the pad point 15.

[0067] A shingled module, the circuit structure diagram of which is shown below. Figure 5 As shown, the device includes several sets of vertically arranged battery strings connected in a shingled manner using the battery cells described in any of the preceding embodiments, with a total of five sets of battery strings. In this embodiment, the battery cell size is 192mm, 200mm, or 210mm in side length. If commonly used battery cells are used, i.e., battery cells with side lengths all less than 192mm are divided into 1 / 2 or 1 / 3, and then the divided battery cells are formed into battery strings, with 6 battery strings arranged side by side, the final module width reaches 1200-1500mm, which seriously exceeds the standard range of 992-1050mm for existing production modules, making mass production impossible and resulting in very low utilization of the battery cell slices.

[0068] Therefore, for solar cells made from large-sized silicon wafers with side lengths of 192mm, 200mm, or 210mm, while ensuring the back surface structure 10 of the solar cell is as described above, the solar cells are divided into 5, 6, 7, or 8 equal parts, and the resulting sliced ​​solar cells are connected in series to form 5 solar cell strings. Then, the 5 solar cell strings are connected in parallel to form a shingled module. This allows the width of the module to be controlled within the range of 1048-1098mm. Moreover, this width of the shingled module does not exceed the limits of the various production equipment on the existing module production line, enabling production line compatibility and mass production. At the same time, it can also be matched with the mass production processes, transportation, and power station end supports of auxiliary materials such as module glass, backsheet, and frame commonly used in the industry.

[0069] Furthermore, for the solar cells of the back surface 10 with different fine grid line spacings 11, they are further cut into 8 equal parts to obtain sliced ​​solar cells. Then, 1 / 8 of the sliced ​​solar cells are connected in series to form a solar cell string. Five solar cell strings of the same structure are then connected in parallel to form shingled modules. With other processes unchanged, the final obtained cell resistance and conversion efficiency are shown in Table 2. As can be seen from Table 2, when the fine grid line spacing 11 is gradually increased from 0.8mm to 1mm, the conversion efficiency gradually increases, especially when the line spacing is 1mm, the conversion efficiency is the highest at 21.42%. When it is gradually increased from 1mm to 1.3mm, the conversion efficiency of the shingled module gradually decreases. From this set of data, it can be seen that when the line spacing is 0.9-1.1mm, the obtained conversion efficiency is relatively high, exceeding 21.3%, and is within the range of 21.38-21.48%.

[0070] Table 2 shows the back field of shingled modules with different grid line spacings, and the resulting resistance and conversion efficiency.

[0071]

[0072] A printing screen for screen printing the back surface 10 of the battery cell as described above, such as... Figure 6 and Figure 7 As shown, it includes a first screen plate 20 and a second screen plate 30. The first screen plate 20 has at least a number of fine grid lines 11 that are parallel to and spaced apart from the sub-grid lines on the front side. The outer dimensions of the second screen plate 30 and the first screen plate 20 are the same as the outer dimensions of the back field 10. The structure of the back field 10 can be obtained by stacking the second screen plate 30 and the first screen plate 20.

[0073] Specifically, the fine grid lines 11 are uniformly distributed on the first screen 20; the line spacing between adjacent fine grid lines 11 is 0.9-1.1 mm; and the width of the fine grid lines 11 is 150-180 μm. Preferably, the line spacing between adjacent fine grid lines 11 is 1 mm.

[0074] Furthermore, such as Figure 6 As shown, the first screen plate 20 is also equipped with at least one back pole slot 12 perpendicular to the fine grid line 11 and several rows of spaced pad slots 13 along the length of the fine grid line 11. The back pole slot 12 is uniformly arranged along the length of the first screen plate 20; and the back pole slot 12 is not superimposed on the main grid line.

[0075] Preferably, the width of the back electrode slot 12 is 4-6 mm; and the number of back electrode slots 12 is 1-5. In this embodiment, three back electrode slots 12 are selected; and there are three rows of pad slots 13. A set of pad slots 13 is symmetrically provided on both sides of each back electrode slot 12.

[0076] Furthermore, such as Figure 7 As shown, the second screen printing plate 30 is used to print the back pole point 14 placed inside the back pole groove 12, the pad point 15 placed inside the pad groove 13, and the positioning point 16 used for cutting and positioning.

[0077] All back pole points 14 are placed in back pole slots 12 and are staggered in a single row along the length of the back pole slots 12. Pad points 15 are placed in pad slots 13 and are set one-to-one with pad slots 13. And positioning points 16 are placed in positioning slots 17.

[0078] In the process, silver paste is first printed using screen 30, which prints all the back poles 14, pads 15 and positioning points 16 formed by the silver paste. In the first printing, there is no need to set the superposition of the recognition mark point 21 and the silicon wafer on screen 30.

[0079] Then, aluminum paste printing is performed using screen 20. This time, the fine grid lines 11, back electrode grooves 12, pad grooves 13, and positioning grooves 17 used to wrap the positioning points 16 are all printed with aluminum paste to obtain the aluminum paste fine grid lines 11 and the back electrode points 14, pad points 15, and positioning points 16 wrapped with aluminum paste. Because the accuracy of the back field 10 needs to be ensured during the second printing, four mark points 21 are also provided on screen 20, which are placed at the ends of the two outermost back electrode grooves 12.

[0080] The separately configured screen printing structure allows for the separate formation of back electrode points 14, pad points 15, and positioning points 16 using silver paste; and fine grid lines 11, back electrode grooves 12, pad grooves 13, and positioning grooves 17 using aluminum paste. The back electrode points 14 and 15 are completely enclosed within the back electrode grooves 12 and 13 formed by the aluminum paste, respectively. This simple printing structure achieves high printing precision, resulting in a stable, efficient, and non-deformable back electrode field 10 for the solar cell.

[0081] This invention discloses a solar cell that replaces the existing back-side aluminum paste covering structure with fine grid lines formed from aluminum paste. This reduces the amount of aluminum paste used in the back-side field while increasing the output power of the solar module, achieving a conversion efficiency of up to 24.48% for the shingled module. It also proposes optimal grid line spacing and line width. Furthermore, it maintains the warpage of the solar cell within the range of 1.1-1.3 mm after back-side field sintering. The invention also includes a double-sided shingled module with this solar cell structure and a printing screen for printing the back-side field structure of the solar cell.

[0082] The embodiments of the present invention have been described in detail above. These descriptions are merely preferred embodiments and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A solar cell comprising a front side having at least one main grid line and a plurality of secondary grid lines arranged at intervals perpendicular to the main grid line, characterized in that, Also includes: It has a back field with several fine gate lines arranged parallel and spaced apart from the sub-gate lines; The fine grid lines are evenly distributed on the back field; The spacing between adjacent fine grid lines is 0.9-1.1 mm; the width of the fine grid lines is 150-180 μm. The back field is also provided with at least one back electrode groove perpendicular to the fine grid line; the back electrode groove is uniformly arranged along the length direction of the back field; the back electrode points of all the battery cells are placed in the back electrode groove and are arranged in a single row with staggered positions along the length direction of the back electrode groove.

2. A solar cell according to claim 1, characterized in that, The spacing between adjacent fine grid lines is 1 mm.

3. A solar cell according to claim 1 or 2, characterized in that, The width of the back electrode slot is 4-6mm; The number of back electrode slots is 1-5; The back pole slot is not superimposed on the main grid line.

4. A solar cell according to claim 3, characterized in that, Several rows of spaced pad slots are provided in the back field along the length direction of the fine grid line; Furthermore, each of the back electrode slots has a set of pad slots symmetrically arranged on both sides; The pad points of the battery cell are placed in the pad slots and are set in a one-to-one correspondence with the pad slots.

5. A solar cell according to claim 4, characterized in that, Both the back electrode groove and the pad groove are structures printed with silver paste. Both the back electrode point and the pad point are aluminum paste printed structures.

6. A shingled component, characterized in that, The battery string comprises several groups of vertically arranged battery cells connected in a shingled manner as described in any one of claims 1-5, and the number of battery strings is five groups.

7. A printing screen for screen printing the back surface of a battery cell as described in any one of claims 1-5, characterized in that, It includes at least a first screen, which has at least a plurality of fine grid lines arranged parallel to and spaced apart from the sub-grid lines.

8. A printing screen according to claim 7, characterized in that, The No. 1 network version is also equipped with: At least one back pole slot perpendicular to the fine grid line; and Several rows of spaced pad slots are provided along the length of the fine grid line; The back electrode groove is uniformly arranged along the length direction of the first screen plate; All the back electrodes of the solar cells are placed in the back electrode slots and are arranged in a single row with staggered positions along the length of the back electrode slots. The fine grid lines are evenly distributed on the No. 1 screen printing plate; The spacing between adjacent fine grid lines is 0.9-1.1 mm; The width of the fine gate line is 150-180μm.

9. A printing screen according to claim 8, characterized in that, The spacing between adjacent fine grid lines is 1 mm; the back pole slots are not superimposed on the main grid lines; the width of the back pole slots is 4-6 mm; the number of back pole slots is 1-5; and a set of pad slots is symmetrically arranged on both sides of each back pole slot.

10. A printing screen according to claim 8 or 9, characterized in that, Also includes: A second screen printing plate is used to print the back electrode point placed inside the back electrode groove and the pad point placed inside the pad groove; the outer dimensions of the second screen printing plate and the first screen printing plate are the same as the back electrode dimensions. All of the back poles are placed in the back pole slots and are arranged in a single row with staggered positions along the length of the back pole slots. The pad points are placed in the pad slots and are set in a one-to-one correspondence with the pad slots.

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