Solar cell and photovoltaic module

Abstract

The invention relates to the technical field of solar cells, in particular to a solar cell and a photovoltaic module. The solar cell comprises a cell body, a bus grid line, a current collection grid line and a lap joint section. The battery body has a battery surface; the bus grid line is arranged on the surface of the battery, and the length direction of the bus grid line is a first direction; the lap joint section is intersected with the bus grid line; the lap joint sections are connected to the current collection grid lines; wherein one side, deviating from the battery body, of the lap joint section is provided with a plurality of raised parts, the raised parts are raised along the direction away from the battery body, the plurality of raised parts are arranged at intervals along a second direction, and the second direction is intersected with the first direction. According to the solar cell, the plurality of raised parts are arranged on the lap joint section, so that welding pulling-out force which is large enough can be formed between the welding strip and the solar cell during welding, the reliability requirement of a photovoltaic module is further met, and the welding yield and the reliability of the photovoltaic module are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a solar cell and a photovoltaic module. BACKGROUND

[0002] The process of making a solar cell into a photovoltaic module utilizes solder strips to be welded with bus bars on the solar cell. However, after the solar cell is welded, the welding tensile force between the solder strip and the bus bar is insufficient, which causes the solder strip to be prone to welding failure. SUMMARY

[0003] Embodiments of the present application disclose a solar cell and a photovoltaic module, which can form a large enough welding tensile force between a solder strip and a solar cell during welding, thereby meeting the reliability requirements of the photovoltaic module.

[0004] To achieve the above-mentioned purpose, in a first aspect, embodiments of the present application disclose a solar cell, comprising:

[0005] a cell body, the cell body having a cell surface;

[0006] a bus bar, the bus bar being arranged on the cell surface, the length direction of the bus bar being a first direction;

[0007] a lap joint section, the lap joint section intersecting with the bus bar; and

[0008] a current collecting grid, the lap joint section being connected to the current collecting grid;

[0009] wherein a side of the lap joint section away from the cell body has a plurality of protrusions, the protrusions protruding in a direction away from the cell body, the plurality of protrusions being arranged in a second direction, the second direction intersecting with the first direction.

[0010] In a possible implementation manner of the first aspect, the lap joint section is a local section of the current collecting grid, and the lap joint section is arranged at the intersection of the current collecting grid and the bus bar.

[0011] In a possible implementation manner of the first aspect, the width of the widest part of the lap joint section in the first direction is W1, the first direction being perpendicular to the second direction; the remaining part of the current collecting grid except the lap joint section is a main body section, and the width of the main body section is W2; wherein W1>W2.

[0012] The widest part of the lap joint section intersects with the bus bar.

[0013] In a possible implementation manner of the first aspect, the lap joint section comprises a lap joint sub-section, and the widest part of the lap joint section is located on the lap joint sub-section.

[0014] The overlap sub-segment is laminated on the side of the bus bar away from the battery body; or the bus bar is laminated on the side of the overlap sub-segment away from the battery body.

[0015] The opposite ends of the overlap sub-segment in the second direction respectively extend out narrowed sub-segments, and the width of each of the narrowed sub-segments in the first direction narrows away from the overlap sub-segment.

[0016] In a possible implementation manner of the first aspect, the rest of the current collecting grid line except the overlap segment is a main body segment.

[0017] In the thickness direction of the battery body, the height of at least one of the protrusions is higher than the height of the main body segment.

[0018] In a possible implementation manner of the first aspect, the rest of the current collecting grid line except the overlap segment is a main body segment.

[0019] The grid line smoothness factor of the main body segment is less than 1 and greater than 0.01; and the width W2 of the main body segment is 5 μm to 20 μm.

[0020] In a possible implementation manner of the first aspect, a part of the protrusions are located on the intersection region of the overlap segment and the bus bar.

[0021] In the second direction, another part of the protrusions are located on both sides of the intersection region of the overlap segment and the bus bar.

[0022] In a possible implementation manner of the first aspect, the protrusions are strips, and the strips extend in the first direction.

[0023] In a possible implementation manner of the first aspect, on the same overlap segment, there is a recess between every two adjacent protrusions; in the thickness direction of the battery body, the distance between the lowest point of the recess and the highest point of the adjacent protrusion in the second direction is D; in the thickness direction of the battery body, the height of the lowest point of the recess is H2, the height of the protrusion adjacent to the recess is H1, and the difference between H1 and H2 is ΔH.

[0024] ΔH / D = 5% to 30%.

[0025] In a possible implementation manner of the first aspect, on the same overlap segment, the distance D between the lowest point of the recess and the highest point of the adjacent protrusion in the second direction is 20 μm to 40 μm.

[0026] And / or, the difference ΔH between H1 and H2 is 3 μm to 6 μm.

[0027] and / or, the height H1 of the protruding part is 6 μm-10 μm;

[0028] and / or, the height H2 of the lowest point of the recessed part is 2 μm-6 μm;

[0029] and / or, the variance of the height values of the plurality of positions of the overlap section along the second direction is 1.2-2.8;

[0030] and / or, the number of the protruding parts is 8-30.

[0031] In a possible implementation of the first aspect, the battery body includes a silicon substrate, a doped layer and a first functional film, the doped layer and the first functional film are sequentially stacked on the surface of the silicon substrate in a direction away from the silicon substrate, the bus bar line is arranged on the side of the first functional film away from the silicon substrate, the collector grid line forms an ohmic contact with the doped layer through the first functional film; the overlap section forms an ohmic contact with the doped layer through the first functional film; or, the overlap section is arranged on the side of the first functional film away from the silicon substrate.

[0032] and / or, the bus bar line and the collector grid line are a plurality of, the plurality of bus bar lines are arranged at intervals along the second direction, the plurality of collector grid lines are arranged at intervals along the first direction, each collector grid line extends along the second direction, and each bus bar line intersects with the plurality of collector grid lines; each intersection of each collector grid line and each bus bar line is provided with the overlap section.

[0033] In a second aspect, the embodiments of the present application disclose a photovoltaic module, comprising a plurality of electrically connected solar cells, at least one of the solar cells being the solar cell of the first aspect.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] The solar cell uses the overlap section with a plurality of protruding parts to be welded with the solder strip, so that the solder strip can be welded with the plurality of protruding parts to form a plurality of welding points, thereby improving the soldering pull-off force between the solder strip and the solar cell and the reliability of the photovoltaic module, and reducing the soldering failure phenomenon.

[0036] Specifically, since the overlap section intersects with the busbar, when welding, the solder strip placed on the busbar can be welded with the overlap section to connect the solar cell, so that the current of the current collecting grid can be directly transmitted to the solder strip through the overlap section, and the current transmission path when the current collecting grid is converged is shortened. On this basis, the side of the overlap section away from the solar cell body has a plurality of protrusions, the protrusions protrude in a direction away from the solar cell body, and the plurality of protrusions are arranged at intervals in the second direction. It can be understood that since the solder strip has a large width in the second direction, the solder strip can contact the plurality of protrusions arranged at intervals in the second direction on each overlap section, so that the solder strip has a plurality of contact positions with each overlap section. The more contact positions, the greater the contact area of the solder strip and the overlap section. The greater the contact area, the greater the resistance to displacement of the solder strip, and the solder strip is less likely to deviate, which is beneficial to the positioning of the solder strip. The more accurate the positioning of the solder strip, the better the subsequent welding quality.

[0037] When welding, the plurality of contact positions between the solder strip and each overlap section are alloyed, and then a plurality of welding points are formed. The more welding points, the greater the welding area, that is, in the present application, each overlap section can form a plurality of welding points with the solder strip, and the welding area is large, which is beneficial to improve the soldering pull-off force between the solder strip and the solar cell and the reliability of the photovoltaic module.

[0038] In summary, by arranging a plurality of protrusions on the overlap section, the solar cell can form a large enough soldering pull-off force between the solder strip and the solar cell during welding, thereby meeting the reliability requirements of the photovoltaic module and improving the soldering yield of the photovoltaic module and the reliability of the photovoltaic module. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0040] Figure 1 A structure diagram of a solar cell (busbar intersects with current collecting grid) disclosed in an embodiment of the present application is shown in the figure.

[0041] Figure 2 A partial enlarged view of the I area shown in the figure. Figure 1

[0042] Figure 3 A A cross-sectional view shown in the figure. Figure 2

[0043] Another partial enlarged view of the I area shown in the figure. Figure 4 Figure 1

[0044] ​​​Figure 5 This is a schematic diagram of the connection between the solar cell and the solder strip disclosed in an embodiment of this application;

[0045] Figure 6 for Figure 5 The BB cross-section shown in the figure;

[0046] Figure 7 This is a schematic diagram of the structure of a solar cell (where the extension lines of the current collector grid intersect) disclosed in an embodiment of this application;

[0047] Figure 8 This is a perspective view of the printing screen disclosed in the embodiments of this application;

[0048] Figure 9 This is a top view of the printing screen disclosed in the embodiments of this application;

[0049] Figure 10 for Figure 9 The CC cross-section shown in the figure;

[0050] Figure 11 This is a schematic diagram of the substrate disclosed in the embodiments of this application during the fabrication of a first adhesive layer, a first conductive layer, a second adhesive layer, and a filament structure in the fabrication of a filament structure.

[0051] Figure 12 This is a schematic diagram of the structure of the substrate disclosed in the embodiments of this application after the third adhesive layer has been fabricated;

[0052] Figure 13 This is a schematic diagram of the structure of the substrate disclosed in the embodiments of this application after the fourth adhesive layer, the second conductive layer and the first metal layer are fabricated in the step of fabricating the screen printing body;

[0053] Figure 14 This is a schematic diagram of the structure of the substrate disclosed in the embodiments of this application after the fifth adhesive layer and the second metal layer are fabricated in the step of fabricating the screen printing body;

[0054] Figure 15 This is a schematic diagram showing the separation of the substrate from the screen printing body after the step of creating the screen printing body, as disclosed in the embodiments of this application.

[0055] Figure 16 A perspective view of a printing screen prepared by the manufacturing method disclosed in the embodiments of this application;

[0056] Figure 17 This is a cross-sectional view of the solar cell in the busbar area disclosed in the embodiments of this application;

[0057] Figure 18 This is a cross-sectional view of the solar cell in the area where the collector grid lines are set, as disclosed in the embodiments of this application;

[0058] Figure 19A cross-sectional view of a solar cell disclosed in the embodiments of the present application at a region where a lap joint section is provided (the lap joint section penetrates a first functional film);

[0059] Figure 20 A cross-sectional view of a solar cell disclosed in the embodiments of the present application at a region where a lap joint section is provided (the lap joint section is provided on a side of the first functional film away from the silicon substrate);

[0060] Figure 21 A structural schematic diagram of a photovoltaic module disclosed in the embodiments of the present application.

[0061] Explanation of reference signs:

[0062] 10, solar cell; 11, cell body; 111, cell surface; 112, silicon substrate; 113, doped layer; 114, first functional film; 115, interface passivation layer; 116, doped polysilicon layer; 117, second functional film; 12, busbar; 13, collector grid line; 131, lap joint section; 1311, raised portion; 1312, recessed portion; 1313, lap joint sub-section; 1314, narrowed sub-section; 132, main body section; Y1, first direction; X1, second direction; Z1, thickness direction of the cell body;

[0063] 20, solder strip; 21, solder joint;

[0064] 30, printing screen; 31, screen body; 311, first metal layer; 312, second metal layer; 32, filamentous structure; 33, printing groove; 331, paste buffering section; 332, paste printing section; 3321, first printing region; 3322, second printing region; X2, third direction; Y2, fourth direction; Z2, thickness direction of the screen body;

[0065] 40, substrate; 41, first adhesive layer; 42, first conductive layer; 43, second adhesive layer; 44, third adhesive layer; 45, fourth adhesive layer; 46, second conductive layer; 47, fifth adhesive layer. DETAILED DESCRIPTION

[0066] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0067] In the present application, the terms "upper", "outer", etc. indicate the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not intended to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0068] In addition, in addition to indicating the orientation or positional relationship, the above-mentioned partial terms can also be used to indicate other meanings, for example, the term "upper" can also be used to indicate a certain dependent relationship or connection relationship in some cases. For those skilled in the art, the specific meaning of these terms in the present application can be understood according to the specific situation.

[0069] In addition, the terms "provided", "provided with", "connected" should be broadly understood. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or internal communication between two devices, elements or components. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific situation.

[0070] In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific type and structure can be the same or different), and are not intended to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise stated, the meaning of "multiple" is two or more.

[0071] The process of making solar cells into photovoltaic modules uses solder strips to weld with the bus bars on the solar cells.

[0072] The inventor found that a lap bar can be arranged at the intersection of the current collecting bar and the bus bar, and the lap bar is welded with the solder strip, so that the current of the current collecting bar is directly transmitted to the solder strip through the lap bar when the welding alignment accuracy is poor, thereby improving the current collection yield. However, in response to the printing cost reduction demand of photovoltaic metallization paste, the height of the metallization bar for collecting current (including bus bar, current collecting bar, lap bar and other bars with current transmission function) is usually designed to be low. Considering that the tin-based alloy on the surface of the solder strip needs a sufficient amount of bar metal to react with it, thereby forming a solder joint with current transmission function, therefore, in the case of low height of the metallization bar, how to form a solder joint between the solder strip and the metallization bar with effective current transmission function and meet the industry standard of solder pull-off force is a technical problem to be solved in industrialization.

[0073] Based on the above analysis, the embodiment of the present application provides a solar cell. The solar cell is capable of forming a large enough welding pull-off force between the solder strip and the solar cell during welding by arranging a plurality of raised portions on the overlapping section. In addition, the solar cell can meet the technical effect of effective current transmission under the industrialization trend of reducing the cost of metallization paste, reduce the welding defect phenomenon, and thus improve the welding yield of photovoltaic modules and the reliability of photovoltaic modules.

[0074] The technical solutions of the present application will be described below in combination with embodiments and drawings.

[0075] In a first aspect, as Figures 1 to 4 shown, the embodiment of the present application discloses a solar cell 10, comprising a cell body 11, a busbar 12, a current collecting grid line 13 and an overlapping section 131.

[0076] The cell body 11 has a cell surface 111. The busbar 12 is arranged on the cell surface 111. The length direction of the busbar 12 is the first direction Y1.

[0077] The overlapping section 131 intersects with the busbar 12, and the overlapping section 131 is connected to the current collecting grid line 13.

[0078] The side of the overlapping section 131 away from the cell body 11 has a plurality of raised portions 1311, the raised portions 1311 are raised in the direction away from the cell body 11, and the plurality of raised portions 1311 are arranged at intervals along the second direction X1, and the second direction X1 intersects with the first direction Y1.

[0079] The beneficial effects of the solar cell of the present application will be described below.

[0080] Please combine Figure 5 and Figure 6 The solar cell 10 is welded with the solder strip 20 by using the overlapping section 131 with a plurality of raised portions 1311, so that the solder strip 20 can be welded with the plurality of raised portions 1311 to form a plurality of welding points, thereby improving the welding pull-off force between the solder strip 20 and the solar cell 10 and the reliability of the photovoltaic module, and reducing the welding defect phenomenon; in addition, since a plurality of raised portions 1311 are designed, it means that a plurality of recesses corresponding to the raised portions 1311 are also designed on the overlapping section 131, thereby reducing the printing wet weight of the paste and achieving the advantage of reducing the industrialization cost.

[0081] Specifically, since the overlap section 131 intersects with the busbar 12, when welding, the solder strip 20 placed on the busbar 12 can be welded with the overlap section 131 to connect the solar cell 10, so that the current of the collecting grid line 13 can be directly transmitted to the solder strip 20 through the overlap section 131 in the case of poor welding alignment accuracy, and the current transmission path of the busbar 12 is shortened. It should be noted that in some embodiments, when the welding accuracy is very high, the solder strip can form effective welding with the busbar 12, but under the industrialization trend of photovoltaic metallization cost reduction, the height of the busbar 12 will also be reduced synchronously, and the overlap section 131 can be stacked on the height of the busbar 12 synchronously. Since effective welding must make the metallized grid line have a certain height, the design of the raised portion 1311 of the overlap section 131 in the present application can also improve the yield of welding. On this basis, the side of the overlap section 131 away from the cell body 11 has a plurality of raised portions 1311, the raised portions 1311 are raised in a direction away from the cell body 11, and the plurality of raised portions 1311 are arranged at intervals in the second direction X1. It can be understood that since the solder strip has a large width in the second direction X1, the solder strip 20 can contact the plurality of raised portions 1311 arranged at intervals in the second direction X1 on each overlap section 131, so that the solder strip 20 has a plurality of contact positions with each overlap section 131. The more the contact positions, the greater the contact area of the solder strip 20 and the overlap section 131. The greater the contact area, the greater the displacement resistance of the solder strip 20, and the solder strip 20 is less likely to deviate, which is beneficial to the positioning of the solder strip 20. The more accurate the positioning of the solder strip 20, the better the subsequent welding quality.

[0082] When welding, the plurality of contact positions between the solder strip 20 and each overlap section 131 are alloyed, and then a plurality of welding points 21 are formed. The more the welding points 21, the larger the welding area, that is, in the present application, each overlap section 131 can form a plurality of welding points 21 with the solder strip 20, and the welding area is large, which is beneficial to improve the soldering pull-off force between the solder strip 20 and the solar cell 10 and the reliability of the photovoltaic module.

[0083] In summary, the solar cell 10 can form a large enough soldering pull-off force between the solder strip 20 and the solar cell 10 when welding by arranging a plurality of raised portions 1311 on the overlap section 131, thereby meeting the reliability requirements of the photovoltaic module and improving the soldering yield of the photovoltaic module and the reliability of the photovoltaic module.

[0084] Optionally, in the present application, the second direction X1 is perpendicular to the first direction Y1. That is, the busbar 12 and the collecting grid line 13 are perpendicular. Of course, the angle between the second direction X1 and the first direction Y1 can also be slightly deviated from 90°, for example, 80°, 85°, 89°, 91°, 95° or 100°.

[0085] The busbar grid line, the current collecting grid line and the overlapping section of the present application will be described in detail below.

[0086] In some embodiments, the overlapping section 131 is a local section of the current collecting grid line 13. In other words, the current collecting grid line 13 intersects with the busbar grid line 12, and the overlapping section 131 is arranged at the intersection of the current collecting grid line 13 and the busbar grid line 12. Figure 1

[0087] That is, the overlapping section 131 is a part of the current collecting grid line 13. Since the current collecting grid line 13 functions to collect current, the overlapping section 131 also has the current collecting function accordingly. In this way, the intersection of the current collecting grid line 13 and the busbar grid line 12 can collect current through the overlapping section 131, so as to improve the current collecting effect of the solar cell 10 at the position, which is conducive to improving the conversion efficiency of the solar cell 10.

[0088] Furthermore, the overlapping section 131 can be printed together when the current collecting grid line 13 is printed, so that the overlapping section 131 for improving the soldering effect and the current collecting effect can be prepared without increasing additional manufacturing procedures.

[0089] Further, the busbar grid line 12 and the current collecting grid line 13 are multiple, the multiple busbar grid lines 12 are arranged at intervals along the second direction X1, the multiple current collecting grid lines 13 are arranged at intervals along the first direction Y1, each current collecting grid line 13 extends along the second direction X1, and each busbar grid line 12 intersects with the multiple current collecting grid lines 13. The overlapping section 131 is arranged at the intersection of each current collecting grid line 13 and each busbar grid line 12. In this way, each current collecting grid line 13 can be converged to the multiple busbar grid lines 12, so as to shorten the current transmission path when the current collecting grid line 13 is converged, and reduce the current transmission loss of the current collecting grid line 13. The current collecting grid line 13 is locally arranged between two busbar grid lines 12, and even if this part is broken, the broken part can still be converged to at least one busbar grid line 12.

[0090] For example, when the number of the busbar grid lines 12 is multiple, the specific number of the busbar grid lines 12 can be two, three, four or other numbers. Of course, the number of the busbar grid lines can also be one. The number of the current collecting grid lines 13 intersecting on each busbar grid line 12 can be tens or other numbers, which are not limited in the embodiments of the present application.

[0091] For example, when the number of the busbar grid lines 12 is multiple, the specific number of the busbar grid lines 12 can be two, three, four or other numbers. Of course, the number of the busbar grid lines can also be one. The number of the current collecting grid lines 13 intersecting on each busbar grid line 12 can be tens or other numbers, which are not limited in the embodiments of the present application. Figure 7 ​In some embodiments, the busbar 12 can also intersect with the extension line of the collector grid line 13. In this case, the collector grid line 13 connects the busbar 12 through the overlap section 131. For example, when the collector grid line 13 is in an intermittent structure, a plurality of collector grid lines 13 are arranged in a row along the second direction X1. Between any two adjacent collector grid lines 13 in a row along the second direction X1, a gap is formed, and the busbar 12 passes through the gap. In this case, the busbar 12 is located on the extension line of the collector grid line 13, and the busbar 12 intersects with the extension line of the collector grid line 13. Although the busbar 12 does not directly intersect with the collector grid line 13, the overlap section 131 can be arranged on the gap. In this case, the overlap section 131 can be a part that does not belong to the collector grid line 13. Along the second direction X1, the opposite ends of the overlap section 131 are connected to the two collector grid lines 13 on both sides of the gap, so that the two intermittent collector grid lines 13 are connected to the busbar 12.

[0092] For the convenience of description, refer back to Figure 2 In this application, when the overlap section 131 is a local section of the collector grid line 13, the remaining part of the collector grid line 13 except the overlap section 131 is the main section 132.

[0093] Further, refer back to Figure 3 In the thickness direction Z1 of the battery body 11, the height of the at least one protruding part 1311 is higher than the height of the main section 132. That is, the at least one protruding part 1311 is more protruding than the main section 132.

[0094] In this way, referring back to Figure 6 When the solder strip 20 is placed on the overlap section 131, the higher protruding part 1311 supports the solder strip 20, so that the solder strip 20 is separated from the lower main section 132, reducing the probability of contact between the main section 132 and the solder strip 20, and further reducing the probability of reaction between the electrode material in the main section 132 and the solder material on the solder strip 20, thereby reducing the risk of disconnection of the main section 132.

[0095] Furthermore, the higher protruding part 1311 has sufficient electrode material, and the probability of complete reaction of the electrode material of the protruding part 1311 by the solder material on the solder strip 20 is low, and the risk of disconnection of the overlap section 131 is low.

[0096] In some embodiments, refer back to Figure 3 On the same overlap section 131, there is a recess 1312 between each two adjacent protruding parts 1311. It can be understood that in the thickness direction Z1 of the battery body 11, the lowest point of the recess 1312 is lower than the highest point of the protruding part 1311. The recess 1312 can be used to reduce the wet weight of the paste when printing the overlap section 131.

[0097] Since the protrusions 1311 are arranged at intervals along the second direction X1 and each adjacent two protrusions 1311 have a recess 1312 therebetween, the protrusions 1311 and the recesses 1312 arranged alternately along the second direction X1 form periodic protrusions and recesses. The longitudinal cross-sectional shape of the lap joint section 131 is a wavy line shape or a sawtooth shape, the longitudinal cross-section being a plane formed by the thickness direction Z1 of the battery body and the second direction X1. The lap joint section 131 periodically repeated along the second direction X1 enables the solder strip 20 to form a plurality of solder joints 21 with the plurality of protrusions 1311 after being offset in the second direction X1, and thus enables a large enough solder pull force to be formed between the solder strip 20 and the solar cell 10. Specifically, the lowest point of the recess 1312 and the highest point of the adjacent protrusion 1311 form one periodic unit.

[0098] Further, in the thickness direction Z1 of the battery body and the interval of the lowest point of the recess 1312 and the highest point of the adjacent protrusion 1311 in the second direction X1 is D. That is, the size of the above-mentioned periodic unit in the second direction X1 is D. In the thickness direction Z1 of the battery body, the height of the lowest point of the recess 1312 is H2, and the height of the protrusion 1311 adjacent to the recess 1312 is H1, the difference between H1 and H2 is ΔH, ΔH = H1 - H2. It can be understood that ΔH / D can represent the degree of fluctuation of the height profile of the lap joint section 131 along the second direction X1.

[0099] In more detail, if ΔH / D < 5%, the fluctuation of the height profile of the lap joint section 131 along the second direction X1 is too flat, and the protrusion 1311 is too low or the recess 1312 is too high, which is not conducive to reducing the risk of broken grid and the wet weight of the paste during printing. If ΔH / D > 30%, the fluctuation of the height profile of the lap joint section 131 along the second direction X1 is too sharp, and the cross-sectional area of the lap joint section 131 at different positions along the second direction X1 is easy to differ greatly, and thus the resistivity of the lap joint section 131 at different positions is easy to differ greatly, and the local position resistivity is easy to be too high, and the current transmission loss is easy to be large.

[0100] Based on this, in some optional embodiments, ΔH / D = 5%~30%, for example, 5%, 10%, 20% or 30%. When ΔH / D satisfies the above ratio range, it indicates that the fluctuation degree of the height profile of the overlap section 131 along the second direction X1 is large enough, the height difference between the raised portion 1311 and the recessed portion 1312 is large enough, and the height of the raised portion 1311 is high enough. The higher the raised portion 1311 is, the more electrode material in the raised portion 1311, and the lower the risk of disconnection. Moreover, the lowest point of the recessed portion 1312 is low enough to effectively reduce the wet weight of the paste during printing of the overlap section 131. However, ΔH / D is not too large to avoid the height profile of the overlap section 131 fluctuating too violently along the second direction X1, thereby making the resistivity of the overlap section 131 at each position in the second direction X1 fluctuate within a reasonable range, which is conducive to reducing the current transmission loss of the overlap section 131.

[0101] Specifically, on the same overlap section 131, the distance D between the lowest point of the recessed portion 1312 and the highest point of the adjacent raised portion 1311 in the second direction X1 is less than 20 μm. Since the distance of the raised portion 1311 in the second direction X1 is substantially equal to D x 2, i.e., the distance of the raised portion 1311 in the second direction X1 will be smaller, the raised portions 1311 are easy to gather together during printing, making it difficult to make a periodically repeated overlap section 131, and the wet weight of the paste during printing will be larger. If the distance D between the lowest point of the recessed portion 1312 and the highest point of the adjacent raised portion 1311 in the second direction X1 is greater than 40 μm, the distance of the raised portion 1311 in the second direction X1 will be larger, and the width of the solder strip 20 in the second direction X1 is limited. After the solder strip 20 is placed, the area of the raised portion 1311 that can be contacted is smaller, which is not conducive to enhancing the soldering pull-off force between the solder strip 20 and the solar cell 10.

[0102] Based on the above analysis, in some optional embodiments, on the same overlap section 131, the distance D between the lowest point of the recessed portion 1312 and the highest point of the adjacent raised portion 1311 in the second direction X1 is 20 μm~40 μm, for example, 20 μm, 30 μm or 40 μm. When the distance D between the lowest point of the recessed portion 1312 and the highest point of the adjacent raised portion 1311 in the second direction X1 satisfies the above distance range, the distance of the raised portion 1311 in the second direction X1 is large enough to reduce the phenomenon of the raised portions 1311 gathering together during printing and to reduce the wet weight of the paste, making it easier to make a periodically repeated overlap section 131. Moreover, the distance of the raised portion 1311 in the second direction X1 is not too large, and after the solder strip 20 is placed, a large number of raised portions 1311 can be contacted, which is conducive to enhancing the soldering pull-off force between the solder strip 20 and the solar cell 10.

[0103] In more detail, if the difference ΔH between H1 and H2 is less than 3 μm, the difference between the height of the recessed portion 1312 and the height of the raised portion 1311 is too small, which results in the raised portion 1311 being too low or the recessed portion 1312 being too high. When the raised portion 1311 is too low, the electrode material in the raised portion 1311 is too little, which is prone to cause grid breakage during soldering. When the recessed portion 1312 is too high, it is prone to cause the wet weight of the paste during printing of the lap joint 131 to be too high. If the difference ΔH between H1 and H2 is greater than 6 μm, the difference between the height of the recessed portion 1312 and the height of the raised portion 1311 is too large, which results in a large fluctuation in the cross-sectional area of the lap joint 131 in the second direction X1, and a region with a small cross-sectional area is prone to occur. The resistivity in the region with a small cross-sectional area is high, and the current transmission loss is high.

[0104] Based on the above analysis, in some optional embodiments, the difference ΔH between H1 and H2 is 3 μm to 6 μm, for example, 3 μm, 4 μm, 5 μm or 6 μm. When the difference ΔH between H1 and H2 satisfies the above numerical range, the difference between the height of the raised portion 1311 and the height of the recessed portion 1312 is large enough, and the height of the raised portion 1311 is high enough, so that more electrode material can be used to react with the soldering material of the solder strip 20 to reduce the grid breakage phenomenon. The recessed portion 1312 also has a suitable height to have a low resistivity, reduce the current transmission loss, and also make the lap joint 131 have a low wet weight of the paste.

[0105] Optionally, the height H1 of the raised portion 1311 is 6 μm to 10 μm, for example, 6 μm, 8 μm or 10 μm. The electrode material contained in the raised portion 1311 is in a positive relationship with the height thereof. When the height H1 of the raised portion 1311 satisfies the above height range, the raised portion 1311 has a high enough height, so that more electrode material can be used to react with the soldering material of the solder strip 20 to reduce the grid breakage probability of the lap joint 131. The raised portion 1311 is not too high, so as to avoid the increase in the wet weight of the paste due to the height being too high. In other words, the wet weight of the paste during printing of the lap joint 131 of the present application is still low.

[0106] Optionally, the height H2 of the lowest point of the recessed portion 1312 is 2 μm to 6 μm, for example, 2 μm, 4 μm or 6 μm. When the height H2 of the lowest point of the recessed portion 1312 satisfies the above height range, the lowest point of the recessed portion 1312 is low enough. Since the wet weight of the paste during printing of the lap joint 131 is in a positive relationship with the height of the lowest point of the recessed portion 1312, when the height of the recessed portion 1312 is low enough, it is beneficial to reduce the wet weight of the paste during printing of the lap joint 131. Furthermore, the recessed portion 1312 is not too low, so as to avoid the cross-sectional area being too small and the resistivity being too high due to the height being too low. In other words, the resistivity at the position of the recessed portion 1312 is still low, and the overall resistivity of the lap joint 131 is low, which is beneficial to reduce the current transmission loss of the lap joint 131.

[0107] It should be noted that for different recesses 1312, the distance D between the lowest point of the recess 1312 and the highest point of the adjacent protrusion 1311 in the second direction X1 can be different, and the height difference ΔH between the recess 1312 and the adjacent protrusion 1311 can also be different. The heights of different protrusions 1311 can also be different. For different recesses 1312, the height H2 of the lowest point of the recess 1312 can also be different.

[0108] In this application, the height variance S 2 is preferably within a certain numerical range. The variance where X1, X2, …, Xn are respectively n height coordinate point values derived from the height curve of the lap joint section. is the average of the n height coordinate point values,

[0109] Specifically, the height variance S 2 of the lap joint section 131 is calculated according to the following formula: S 2 = 1 / n Σ (Xi - X)2, where X is the average of the n height coordinate point values, and n is the number of the height coordinate point values. One of the test methods is as follows: using a 3D microscope to measure the height profile of the grid line at any magnification (for example: 50 times), and based on the height curve measured by the height profile, deriving multiple height coordinate point values from the height curve, for example, deriving 1024 height coordinate point values, at this time n = 1024, and calculating the variance S 2 of the 1024 height point values according to the above formula to represent the fluctuation size of the height of the lap joint section 131. It can be understood that the larger the variance S 2 , the greater the fluctuation of the height of the lap joint section 131. 2

[0110] It should be noted that along the second direction X1, if the variance of the height values of multiple positions of the lap joint section 131 is less than 1.8, the height change of the lap joint section 131 is too flat, which leads to the protrusion 1311 not being obvious, and it is difficult to form multiple obvious protrusions 1311 in contact with the solder strip 20, thereby improving the welding quality. Along the second direction X1, if the variance of the height values of multiple positions of the lap joint section 131 is greater than 2.2, the height change of the lap joint section 131 fluctuates too much, and since the electrical resistivity changes with the height value, the electrical resistivity of the lap joint section 131 also has a large fluctuation, which is prone to occur at a position with high electrical resistivity, thereby leading to large current transmission loss of the lap joint section 131.

[0111] ​Based on the above analysis, in some optional embodiments, the variance of the height values of the plurality of positions of the overlap section 131 along the second direction X1 is 1.2-2.8, for example, 1.2, 1.6, 1.8, 2.0, 2.2, 2.6, or 2.8. When the overlap section 131 satisfies the above variance range, a protruding bump 1311 can be formed on the overlap section 131, the protruding bump 1311 contacts and is welded with the solder strip 20 to form a plurality of solder joints 21, thereby enhancing the soldering pull-off force between the solder strip 20 and the solar cell 10. In addition, the height of the overlap section 131 does not fluctuate too much along the second direction X1, and the resistivity of the overlap section 131 at different positions fluctuates less, which is beneficial to reduce the current transmission loss of the overlap section 131, and further improve the conversion efficiency of the solar cell 10.

[0112] Optionally, referring to Figure 4 , the overlap section 131 extends along the second direction X1. The width of the widest part of the overlap section 131 in the first direction Y1 is W1. The width of the main body section 132 in the first direction Y1 is W2. Wherein, W1>W2. The widest part of the overlap section 131 intersects with the busbar 12.

[0113] In this way, the width of the main body section 132 is narrower, and the narrower main body section 132 makes the overall light shielding area of the collector grid line 13 smaller, thereby enhancing the light absorption rate of the solar cell 10, which is beneficial to improve the conversion efficiency of the solar cell 10.

[0114] Please refer to Figure 5 , considering that the overlap section 131 needs to be welded with the solder strip 20, the welding material on the solder strip 20 will react with the electrode material in the overlap section 131. It should be noted that when the electrode material for current transmission in the grid line is completely reacted with the welding material on the solder strip 20, the grid line will appear a phenomenon that the current cannot be normally transmitted, i.e., the current transmission is disconnected, which is referred to as the grid line breaking phenomenon in the present application. It can be understood that the more electrode material contained in the grid line, the lower the probability that the electrode material is completely reacted with the welding material on the solder strip 20, and the lower the probability of the grid line breaking phenomenon. In order to reduce the risk of the grid line breaking of the overlap section 131, in the present embodiment, the widest part of the overlap section 131 is wider relative to the main body section 132. That is, compared with the main body section 132, the widest part of the overlap section 131 is printed with more paste, and the widest part of the overlap section 131 contains more electrode material for reaction with the welding material on the solder strip 20, so that the widest part of the overlap section 131 is less likely to have the grid line breaking phenomenon during welding.

[0115] On this basis, the widest part of the overlap section 131 intersects with the busbar 12, and the overlap section 131 contacts the solder strip 20 placed along the busbar 12 by using the widest part. In this way, the probability of the grid line breaking phenomenon of the overlap section 131 after welding will be reduced.

[0116] More specifically, the reaction between the solder material and the electrode material is, for example, a silver etching reaction, which refers to a reaction between the tin-based alloy on the surface of the solder strip 20 and the silver in the grid line, which reduces the silver content in the grid line. That is, the electrode material can be silver, and the solder material can be a tin-based alloy.

[0117] It should be noted that the lap section 131 has a widest part, and this is not particularly specified as the width of the lap section 131 varies. Even if the width of the lap section 131 is uniform, the lap section 131 has a widest part, for example, a square lap section 131, and the widest part of the lap section 131 can be any position in the length direction thereof due to the uniform width of the lap section 131.

[0118] In addition, the lap section can also not be a part of the current collecting grid line. In other words, the lap section can also be printed separately from the current collecting grid line. In this case, the width of the widest part of the lap section in the first direction can also be greater than the width of the current collecting grid line.

[0119] In some embodiments, referring back to Figure 4 The lap section 131 includes a lap sub-section 1313, and the widest part of the lap section 131 is located on the lap sub-section 1313.

[0120] That is, the lap sub-section 1313 intersects the busbar grid line 12. The solder strip 20 placed along the extension direction of the busbar grid line 12 can just contact the lap sub-section 1313, and the lap sub-section 1313 has a relatively wide width, so that it has more electrode material to react with the solder material of the solder strip 20, thereby reducing the probability of grid breakage after soldering of the lap section 131.

[0121] Further, the opposite ends of the lap sub-section 1313 in the second direction X1 extend out narrowed sub-sections, respectively, and the width of each narrowed sub-section 1314 in the first direction Y1 narrows away from the lap sub-section 1313. The narrowed sub-section 1314 with a narrowed width can reduce the overall light shielding area of the lap section 131 and the wet weight of the paste during printing. Moreover, since the farther the position of the narrowed sub-section 1314 from the lap sub-section 1313, the lower the probability of contact with the solder strip 20, the narrowed sub-section 1314 narrows away from the lap sub-section 1313, that is, the position of the narrowed sub-section 1314 with a high probability of contact with the solder strip 20 has a relatively wide width, and the position of the narrowed sub-section 1314 with a low probability of contact with the solder strip 20 has a relatively narrow width, thereby reducing the probability of grid breakage when the narrowed sub-section 1314 is soldered with the solder strip 20.

[0122] Furthermore, since the lap sub-section 1313 is wider than the main body section 132, the narrowing sub-section 1314 can also be used to connect the lap sub-section 1313 and the main body section 132, so that the wider lap sub-section 1313 is transitioned to the narrower main body section 132, which is conducive to improving the continuity of the overall structure of the current collecting grid line 13.

[0123] In more detail, the shape of the lap sub-section 1313 can be square. The narrowing sub-section 1314 can be tapered, and the shape of the tapered narrowing sub-section 1314 is, for example, trapezoidal or triangular. The narrowing sub-section 1314 can also be tapered in a stepped manner.

[0124] It can be understood that, as shown in Figure 4 When the current collecting grid line 13 is printed first and then the bus grid line 12 is printed, the lap sub-section 1313 is stacked on the side of the bus grid line 12 away from the battery body. When the current collecting grid line is printed first and then the bus grid line is printed, the bus grid line is stacked on the side of the lap sub-section away from the battery body. At the stacking position of the lap sub-section 1313 and the bus grid line 12, the heights of the two are added.

[0125] The lap section of the present application will be described in detail below.

[0126] Please refer to Figure 4 and Figure 5 Since the solder strip 20 is placed along the bus grid line 12, the intersection area of the lap section 131 and the bus grid line 12 has a higher probability of contacting the solder strip 20. In some embodiments, a portion of the number of protrusions 1311 is located on the intersection area of the lap section 131 and the bus grid line 12. In this way, when the solder strip 20 is just placed on the bus grid line 12, the solder strip 20 can contact the protrusions 1311 located on the intersection area of the lap section 131 and the bus grid line 12, and these protrusions 1311 can form solder joints 21 with the solder strip 20, so that a large enough solder pull-off force is formed between the solder strip 20 and the solar cell 10.

[0127] As Figure 4 and Figure 5As shown, further, in the second direction X1, another portion of the number of the protrusions 1311 are located on both sides of the intersection region of the overlap section 131 and the busbar 12. In this way, when the width of the solder strip 20 in the second direction X1 is wider than the width of the busbar 12, along the second direction X1, the solder strip 20 protrudes on both sides of the width direction of the busbar 12, the portion of the solder strip 20 protruding the busbar 12 can contact the protrusions 1311 on both sides of the intersection region, so that more solder joints 21 are formed between the solder strip 20 and the overlap section 131, further improving the soldering pull-off force between the solder strip 20 and the solar cell 10. When the solder strip 20 is offset in the second direction X1, the solder strip 20 can still contact the protrusions 1311 on both sides of the intersection region, and the protrusions 1311 can also form solder joints 21 with the solder strip 20, thereby forming a large enough soldering pull-off force between the solder strip 20 and the solar cell 10 when the solder strip 20 is offset.

[0128] With reference to Figure 4 and Figure 5 Optionally, the protrusions 1311 are strips, and the strips of the protrusions 1311 extend along the first direction Y1. It can be understood that since the solder strip 20 is also placed along the first direction Y1, in this way, the protrusions 1311 extending along the first direction Y1 form strip-shaped solder joints 21 with the solder strip 20 after soldering, and such strip-shaped solder joints 21 have a large soldering area, which is conducive to further improving the soldering pull-off force between the solder strip 20 and the solar cell 10, and further improving the reliability of the photovoltaic module using the solar cell 10.

[0129] Of course, the protrusions can also be blocks, such as circular blocks, oval blocks, etc., and the shape of the protrusions is not limited in the embodiments of the present application.

[0130] It should be noted that, with reference back to Figure 4 and Figure 5 If the number of the protrusions 1311 is less than 8, the protrusions 1311 on the overlap section 131 are spaced apart, and since the width of the solder strip 20 in the second direction X1 is limited, the number of the protrusions 1311 in contact with the solder strip 20 is small. If the number of the protrusions 1311 is more than 30, the overlap section 131 has a large wet weight of paste due to the increase in the number of the protrusions 1311.

[0131] Optionally, the number of the protrusions 1311 is 8-30, such as 8, 10, 20, or 30. When the number of the protrusions 1311 meets the above range, the protrusions 1311 on the overlap section 131 are moderately spaced apart, which is conducive to the solder strip 20 contacting and soldering with a sufficient number of the protrusions 1311 to form a sufficient number of solder joints 21 to enhance the soldering pull-off force between the solder strip 20 and the solar cell 10. Furthermore, the overlap section 131 has a low wet weight of paste during printing.

[0132] The main body of this application will be further explained below.

[0133] In some alternative embodiments, such as Figure 4 As shown, the width W2 of the main body segment 132 is 5μm to 20μm, for example, 5μm, 10μm, 15μm, or 20μm. When the width W2 of the main body segment 132 meets the above-mentioned width range, the main body segment 132 is relatively narrow, thus having a lower light-blocking area and a lower wet weight of the ink during printing. Furthermore, the main body segment 132 also avoids excessively high resistivity and poor printing morphology caused by being too narrow; that is, the main body segment 132 also has lower resistivity and better printing morphology.

[0134] Based on this, the grid line smoothing factor of main segment 132 is A. 2 A 2 Less than 1 and greater than 0.01. Gate smoothing factor. Where Y1, Y2, ..., Yn are the n height coordinate points derived from the height curve of the main body segment. It is the average value of the n height coordinates of the main segment.

[0135] Specifically, one method for testing the grid line smoothing factor is as follows: The height profile of the grid line is measured using a 3D microscope at any magnification (e.g., 50x). Based on the height curve obtained from the height profile, multiple height coordinate point values ​​are derived from the height curve. For example, in some embodiments of this application, 1024 height coordinate point values ​​are derived, where n = 1024. Then, based on the aforementioned grid line smoothing factor A... 2 The variance of these 1024 height point values ​​is calculated using the formula. This variance is used to characterize the fluctuation of the grid line height, which is the grid line smoothing factor A described in this application. 2 .

[0136] Understandably, the grid line smoothing factor A 2 The smaller the coefficient of friction, the smaller the height fluctuation of the grid lines. In this application, the grid line smoothing factor of the main body segment 132 is <1, indicating that the height fluctuation of the main body segment 132 is small. Along the second direction X1, the height of the main body segment 132 is relatively uniform, and the cross-sectional area of ​​the main body segment 132 varies little. Since the resistivity of the main body segment 132 is related to its cross-sectional area, when the cross-sectional area of ​​the main body segment 132 varies little, the resistivity of the main body segment 132 is also approximately the same. This avoids the phenomenon of excessively high resistivity in local locations, which is beneficial to improving the current transport performance of the main body segment 132, thereby improving the conversion efficiency of the solar cell.

[0137] It should be noted that the narrower the width of the grid line, the narrower the width of the printing groove on the printing screen plate, the worse the paste passability, the worse the shaping effect of the grid line, and the grid line with poor plasticity is prone to have a large high-low fluctuation, and the grid line printed has a high grid line smoothness factor. In other words, it is difficult for the grid line to have a narrow width and a low grid line smoothness factor. The main body section 132 of the present application has both a narrow width and a small grid line smoothness factor.

[0138] The printing method of the main body section and the lap joint section of the present application will be described below.

[0139] In the present application, please refer to Figure 8 to 10 , Figure 8 A printing screen plate 30 for printing the above-mentioned current collecting grid line is disclosed, which comprises a screen plate main body 31 and a filament structure 32.

[0140] The screen plate main body 31 is provided with a printing groove 33, which penetrates the screen plate main body 31 along the thickness direction Z2 of the screen plate main body, and the length direction of the printing groove 33 is the third direction X2.

[0141] The filament structure 32 is arranged at the position of the screen plate main body 31 provided with the printing groove 33. Along the third direction X2, the filament structure 32 is arranged corresponding to the local area of the printing groove 33. The filament structure 32 extends along the fourth direction Y2, and the fourth direction Y2 intersects the third direction X2.

[0142] For the convenience of understanding, Figure 8 and Figure 9 Only one printing groove 33 is shown on the printing screen plate 30. It should be noted that the number of printing grooves 33 on the printing screen plate 30 can also be two, three or four, which is not limited in the embodiments of the present application.

[0143] Further, along the thickness direction Z2 of the screen plate main body, the printing groove 33 comprises a paste buffering section 331 and a paste printing section 332 connected in series. The width of the paste buffering section 331 is W3, for example, W3 is 50 μm-200 μm. Along the third direction X2, the paste printing section 332 has a first printing area 3321 and a second printing area 3322 connected in series. The width of the first printing area 3321 is W4, for example, W4 is 3 μm-15 μm. The width of the widest part of the second printing area 3322 is W5, for example, W5 is 10 μm-100 μm. Wherein, W3≥W5, and W5>W4.

[0144] For the convenience of understanding, Figure 8 and Figure 9Only two second printing areas 3322 are shown on the printing slot 33. It should be noted that the second printing areas 3322 on the printing slot 33 can also be one, three, four, etc., and the embodiments of the present application do not limit this. When the first printing areas 3321 and the second printing areas 3322 are both multiple, the first printing areas 3321 and the second printing areas 3322 are alternately arranged along the third direction X2.

[0145] Specifically, the first printing areas 3321 are configured to print the body section, and thus the patterns of the first printing areas 3321 correspond to the patterns of the body section. The opening rate of the first printing areas 3321 is greater than or equal to 80% and less than or equal to 100%.

[0146] It should be noted that the grid line smoothing factor of the body section is inversely proportional to the opening rate of the first printing areas 3321. Specifically, the higher the opening rate of the first printing areas 3321, the smaller the shielding within the first printing areas 3321, the better the slurry passability, and the grid lines printed by the first printing areas 3321 with the opening rate greater than or equal to 80% and less than or equal to 100% have both a relatively narrow width and a relatively small grid line smoothing factor value. In other words, the body section printed by the first printing areas 3321 with the opening rate greater than or equal to 80% and less than or equal to 100% has both a relatively narrow width and a relatively small grid line smoothing factor.

[0147] On the other hand, the second printing areas 3322 are configured to print the overlap section, and thus the patterns of the second printing areas 3322 correspond to the patterns of the overlap section.

[0148] Further, the filamentous structure 32 is arranged in the slurry buffer section 331 and corresponds to the second printing areas 3322. Due to the arrangement of the filamentous structure 32, the opening rate of the second printing areas 3322 is greater than or equal to 30% and less than or equal to 70%.

[0149] In the present application, the doctor blade can extend into the relatively wide slurry buffer section 331 to scrape off the slurry stored in the slurry buffer section 331. Since the first printing areas 3321 are relatively narrow, the doctor blade cannot extend into the first printing areas 3321. Then, the height of the grid lines printed by the first printing areas 3321 corresponds to the depth of the slurry printing section 332.

[0150] And, in the second printing areas 3322, the filamentous structure 32 blocks the doctor blade from further extending into the second printing areas 3322. The doctor blade also has difficulty in scraping off the slurry filled between the adjacent filamentous structures 32, and this part of the slurry between the two adjacent filamentous structures 32 is superimposed on the slurry of the second printing areas 3322 to form a raised portion. Correspondingly, the position where the filamentous structure 32 is located will not be filled with slurry to form a recessed portion.

[0151] In this way, the second printing areas 3322 print the overlap section with the raised portion.

[0152] In more detail, referring to Figure 10 The screen body 31 comprises a first metal layer 311 and a second metal layer 312 stacked along the thickness direction Z2 of the screen body. Along the thickness direction Z2 of the screen body, the paste printing section 332 penetrates the first metal layer 311, and the paste buffering section 331 penetrates the second metal layer 312.

[0153] The filamentous structure 32 can be formed on the screen body 31 by electroforming or electroplating. Alternatively, the filamentous structure 32 can be obtained by a steel wire that is tied and knotted.

[0154] In more detail, referring to Figures 11 to 16 A method for manufacturing a printing screen, comprising the following steps:

[0155] Manufacturing the filamentous structure 32: manufacturing the filamentous structure 32 on a substrate;

[0156] Manufacturing the screen body 31: manufacturing the screen body 31 with the printing groove 33 on the substrate with the filamentous structure 32.

[0157] The step of manufacturing the filamentous structure of the present application is described in detail below.

[0158] In some embodiments, the step of manufacturing the filamentous structure comprises the following sub-steps:

[0159] Manufacturing the first adhesive layer: referring to (A) of Figure 11 manufacturing the first adhesive layer 41 on a partial area of the non-conductive substrate 40;

[0160] Depositing the first conductive layer: referring to (B) of Figure 11 depositing the first conductive layer 42 on the side of the first adhesive layer 41 away from the substrate 40;

[0161] Manufacturing the patterned second adhesive layer: referring to (C) of Figure 11 manufacturing the patterned second adhesive layer 43 on the side of the first conductive layer 42 away from the first adhesive layer 41, so that a partial area of the first conductive layer 42 is exposed to the second adhesive layer 43, and the exposed area of the first conductive layer 42 corresponds to the pattern of the filamentous structure 32;

[0162] Electrodepositing the filamentous structure: referring to (D) of Figure 11 electrodepositing the filamentous structure 32 on the exposed area of the first conductive layer 42.

[0163] The material of the substrate 40 is, for example, glass, non-conductive resin or polymer material.

[0164] The first glue layer 41 is, for example, ultraviolet light curing glue (UV glue) or other types of non-conductive glue, and the thickness of the first glue layer 41 is, for example, 2-15 μm. The first glue layer 41 can be made by coating or printing. The first glue layer 41 serves as a spacer, so that the subsequent wire-like structure 32 is at a certain distance from the substrate 40, so that the wire-like structure 32 can be combined with the subsequently made second metal layer 312.

[0165] The material of the first conductive layer 42 is, for example, nickel-based alloy or copper alloy, and the thickness of the first conductive layer 42 can be 10-15 nm. The first conductive layer 42 can be deposited by, for example, PVD (Physical Vapor Deposition, physical vapor deposition). The first conductive layer 42 serves as a conductive base for the wire-like structure 32 to be electrodeposited.

[0166] The second glue layer 43 can be ultraviolet light curing glue (UV glue) or other types of non-conductive glue. The second glue layer 43 can be made by coating or printing. It can be understood that, due to the arc-shaped edge of the wire-like structure, the edge of the second glue layer 43 also has an arc-shaped edge. After the first conductive layer 42 is printed with the second glue layer 43, the pattern of the exposed area of the first conductive layer 42 is the same as that of the wire-like structure 32. In this way, the exposed area of the first conductive layer 42 can be provided with the wire-like structure 32 by electrodeposition, for example, electroforming.

[0167] The steps of making the screen body in the present application will be described in detail below.

[0168] In some embodiments, before the step of making the screen body, the method further comprises the following steps:

[0169] Making the third glue layer 44: referring to Figure 12 The third glue layer 44 covers the wire-like structure 32.

[0170] The third glue layer 44 can be ultraviolet light curing glue (UV glue) or other types of non-conductive glue. The third glue layer 44 can be made by coating or printing. The third glue layer 44 serves to shield the wire-like structure 32, so that the wire-like structure 32 does not continue to be deposited upward during the process of making the screen body 31. Specifically, the third glue layer 44 also covers the side of the second glue layer 43 away from the substrate 40.

[0171] Further, the step of making the screen body comprises the following sub-steps:

[0172] Making the fourth glue layer: referring to Figure 13 (A) making the fourth glue layer 45 on the local area of the substrate 40; wherein the fourth glue layer 45 is connected to the third glue layer 44, and the pattern after the connection corresponds to the pattern of the printing section of the printing slot.

[0173] Depositing the second conductive layer: refer to Figure 13 (B) of FIG. 1, depositing the second conductive layer 46 on the substrate 40 except the third adhesive layer 44 and the fourth adhesive layer 45;

[0174] Electrodepositing the first metal layer: refer to Figure 13 (C) of FIG. 1, electrodepositing the first metal layer 311 on the side of the second conductive layer 46 away from the substrate 40; wherein the side of the first metal layer 311 away from the substrate 40 is below the bottom surface of the filament structure 32 along the thickness direction of the substrate 40;

[0175] Making the fifth adhesive layer: refer to Figure 14 (A) of FIG. 1, making the fifth adhesive layer 47 on the partial area of the first metal layer 311, the pattern of the fifth adhesive layer 47 corresponds to the pattern of the printing slot;

[0176] Making the second metal layer: refer to Figure 14 (B) of FIG. 1, making the second metal layer 312 on the exposed area of the first metal layer 311, so that the filament structure 32 is connected to the second metal layer 312, and the screen plate body 31 is made; wherein the second metal layer 312 is formed with the slurry buffer section 331.

[0177] The fourth adhesive layer 45 can be ultraviolet curing adhesive (UV adhesive) or other types of non-conductive glue. The fourth adhesive layer 45 can be made by coating or printing. The thickness of the fourth adhesive layer 45 is, for example, 3 μm to 15 μm. The fourth adhesive layer 45 is used to be connected with the third adhesive layer 44, and the pattern of the connected fourth adhesive layer 45 corresponds to the pattern of the slurry printing section 332 of the printing slot 33. In this way, when the metal is deposited subsequently, the fourth adhesive layer 45 and the third adhesive layer 44 will not be deposited with metal, thereby forming the slurry printing section 332.

[0178] The material of the second conductive layer 46 is, for example, nickel-based alloy or copper alloy, and the thickness of the second conductive layer 46 can be 10 nm to 15 nm. The first conductive layer 42 is deposited by, for example, PVD (Physical Vapor Deposition). The second conductive layer 46 is used to provide a conductive basis for the electrodepositing of the first metal layer 311.

[0179] The electrodepositing of the first metal layer 311 is, for example, electroplating. Since the side of the first metal layer 311 away from the substrate 40 is below the bottom surface of the filament structure 32, the subsequently electrodepositing second metal layer 312 will be combined with the filament structure 32, so that the filament structure is arranged in the slurry buffer section and corresponds to the second printing area.

[0180] The fifth adhesive layer 47 can be ultraviolet light curing adhesive (UV adhesive) or other types of non-conductive glue. The fifth adhesive layer 47 can be made by coating or printing. When the metal is deposited subsequently, the metal will not be deposited on the surface of the fifth adhesive layer 47, thereby forming the slurry buffer section 331.

[0181] The second metal layer 312 is deposited by electroplating. It can be understood that, during the process of depositing the second metal layer 312, the filament structure 32 can be combined with the deposited metal when the metal is deposited to the same height of the filament structure 32, and the second metal layer 312 is combined with the filament structure 32 integrally.

[0182] Further, after the step of making the screen body, the making method further comprises the following steps:

[0183] Separating the screen body: referring to Figure 15 separating the screen body 31 from the substrate 40;

[0184] Degumming: removing the first adhesive layer 41, the second adhesive layer 43, the third adhesive layer 44, the fourth adhesive layer 45, and the fifth adhesive layer 47 on the screen body;

[0185] Removing the first conductive layer 42.

[0186] The screen body 31 can be separated from the substrate 40.

[0187] The degumming method can be to dissolve and remove the first adhesive layer 41, the second adhesive layer 43, the third adhesive layer 44, the fourth adhesive layer 45, and the fifth adhesive layer 47 by using a degumming agent. The degumming agent can be selected according to the material of the adhesive layer, which will not be described here.

[0188] The first conductive layer 42 can be removed by heat treatment and ultrasonic cleaning. Since the first conductive layer 42 is thin, with a thickness of only 10-15 nm, and the thickness of the first metal layer and the second metal layer is 5-20 μm, which is much larger than the thickness of the first conductive layer, removing the thin first conductive layer 42 will not have a great impact on the thicker first metal layer 311 and the second metal layer 312. In addition, the second conductive layer 46 can be removed together during the process of removing the first conductive layer 42.

[0189] Referring to Figure 16 The printing screen 30 made by the making method comprises the screen body 31 and the filament structure 32.

[0190] The screen body 31 is provided with a printing groove 33, which penetrates the screen body 31 along the thickness direction Z2 of the screen body, and the length direction of the printing groove 33 is the third direction X2.

[0191] The filamentary structure 32 is arranged on the screen body 31 at a position where the printing groove 33 is provided. In the third direction X2, the filamentary structure 32 is arranged corresponding to a partial region of the printing groove 33. The filamentary structure 32 extends in the fourth direction Y2, which intersects the third direction X2.

[0192] The battery body of the present application will be described in detail below.

[0193] In some embodiments, as shown in Figure 17 and Figure 18 The battery body 11 includes a silicon substrate 112, a doped layer 113, and a first functional film 114, which are sequentially stacked on a surface of the silicon substrate 112 in a direction away from the silicon substrate 112. The busbar 12 is arranged on a side of the first functional film 114 away from the silicon substrate 112. The collector grid 13 forms an ohmic contact with the doped layer 113 through the first functional film 114 to collect photo-generated carriers in the doped layer 113.

[0194] It should be noted that, as shown in Figure 19 When the overlapping section 131 is a partial section of the collector grid 13, the overlapping section 131 forms an ohmic contact with the doped layer 113 through the first functional film 114, so that the overlapping section 131 can collect photo-generated carriers in the doped layer 113 to improve the current collection effect of the collector grid 13. Of course, as shown in Figure 20 The overlapping section 131 can also be arranged on a side of the first functional film 114 away from the silicon substrate 112 to reduce damage to the first functional film 114.

[0195] In more detail, the silicon substrate 112 can be an N-type silicon substrate or a P-type silicon substrate. The doped layer 113 can be a diffusion layer, such as an N-type diffusion layer or a P-type diffusion layer. The doped layer 113 can also be an N-type doped polysilicon layer or a P-type doped polysilicon layer. The first functional film 114 can be a passivation film and / or an anti-reflection film. The material of the first functional film 114 can be silicon nitride, silicon oxynitride, silicon oxide, or aluminum oxide.

[0196] For example, the solar cell 10 can be a passivated contact solar cell, the doped layer 113 and the first functional film 114 can be arranged on the light-receiving surface and / or the back surface of the silicon substrate 112, and the cell surface 111 is the surface of the first functional film 114 away from the silicon substrate 112. In other words, the collector grid lines 13, the overlapping segments 131 and the bus bar grid lines 12 can be arranged on the light-receiving surface and / or the back surface of the silicon substrate 112. When the doped layer 113 and the first functional film 114 are arranged on the light-receiving surface of the silicon substrate 112, the cell body 11 further comprises an interface passivation layer 115, a doped polysilicon layer 116 and a second functional film 117, which are sequentially stacked on the back surface of the silicon substrate 112 in a direction away from the silicon substrate 112.

[0197] In more detail, the material of the interface passivation layer 115 can be at least one of silicon oxide, magnesium fluoride, amorphous silicon, polysilicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide or titanium oxide. The second functional film 117 can be a passivation film and / or an anti-reflection film. The material of the second functional film 117 can be silicon nitride, silicon oxynitride, silicon oxide or aluminum oxide.

[0198] As other examples, the cell type of the solar cell can also be a heterojunction solar cell or a back contact solar cell.

[0199] In a second aspect, as shown in Figure 21 The embodiments of the present application disclose a photovoltaic module, comprising a plurality of electrically connected solar cells 10, at least one of the solar cells 10 being the solar cell 10 of the first aspect.

[0200] In more detail, the electric connection mode of the solar cell 10 is, for example, series connection and / or parallel connection.

[0201] The beneficial effects of the photovoltaic module of the present application are described below.

[0202] The solar cells 10 of the photovoltaic module are electrically connected by the solder strips 20. Since the solar cell 10 is provided with a plurality of protrusions 1311 on the overlapping segments 131, a large enough solder pull-off force can be formed between the solder strip 20 and the solar cell 10 during soldering, thereby meeting the reliability requirements of the photovoltaic module, reducing the phenomenon of broken grid lines during soldering, and improving the soldering yield of the photovoltaic module and the reliability of the photovoltaic module.

[0203] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A solar cell, characterized by, The battery body has a battery surface; The bus bar grid line is provided on the battery surface, and the length direction of the bus bar grid line is a first direction; The overlap section is connected to the current collecting grid line; Wherein, the side of the overlap section away from the battery body has a plurality of protrusions, the protrusions protrude in a direction away from the battery body, and a plurality of the protrusions are arranged in a second direction intersecting the first direction. The overlap section is a local section of the current collecting grid line, and the overlap section is arranged at the intersection of the current collecting grid line and the bus bar grid line. The widest part of the overlap section has a width W1 in the first direction perpendicular to the second direction; the rest of the current collecting grid line except the overlap section is a main section, and the width of the main section is W2; wherein W1>W2; The widest part of the overlap section intersects the bus bar grid line.

2. The solar cell according to claim 1, characterized in that, The overlap section includes an overlap sub-section, and the widest part of the overlap section is located on the overlap sub-section; 3. The solar cell according to claim 2, characterized in that, The overlap sub-section is laminated on the side of the bus bar grid line away from the battery body, or the bus bar grid line is laminated on the side of the overlap sub-section away from the battery body; The opposite ends of the overlap sub-section in the second direction respectively extend out narrowed sub-sections, and the width of each narrowed sub-section in the first direction narrows in a direction away from the overlap sub-section.

4. The solar cell according to claim 3, characterized in that, The rest of the current collecting grid line except the overlap section is a main section; In the thickness direction of the battery body, the height of at least one protrusion is higher than the height of the main section. The rest of the current collecting grid line except the overlap section is a main section; 5. The solar cell according to claim 2, characterized in that, The grid line smoothness factor of the main section is less than 1 and greater than 0.01, and the width W2 of the main section is 5-20 μm. A part of the protrusions are located on the intersection area of the overlap section and the bus bar grid line; 6. The solar cell according to claim 2, characterized in that, In the second direction, another part of the protrusions are located on both sides of the intersection area of the overlap section and the bus bar grid line. The protrusions are strips, and the strips extend in the first direction.

7. The solar cell according to claim 1, characterized in that, On the same overlap section, each adjacent two protrusions have a recess therebetween; in the thickness direction of the battery body, the lowest point of the recess and the highest point of the adjacent protrusion in the second direction have a spacing D; in the thickness direction of the battery body, the height of the lowest point of the recess is H2, the height of the protrusion adjacent to the recess is H1, and the difference between H1 and H2 is ΔH; Wherein, ΔH / D=5%-30%.

8. The solar cell according to claim 1, characterized in that, On the same overlap section, the spacing D between the lowest point of the recess and the highest point of the adjacent protrusion in the second direction is 20-40 μm; 9. The solar cell according to any one of claims 1 to 8, characterized in that, And / or, the difference ΔH between H1 and H2 is 3-6 μm; And / or, the height H1 of the protrusion is 6-10 μm; 10. The solar cell according to claim 9, characterized in that, And / or, the height H2 of the lowest point of the recess is 2-6 μm; ​ ​ ​ And / or, the variance of the height values of the plurality of positions of the overlap section along the second direction is 1.2-2.8; And / or, the number of the protrusions is 8-30.

11. The solar cell according to any one of claims 1 to 8, characterized in that, The battery body comprises a silicon substrate, a doped layer and a first functional film, the doped layer and the first functional film are sequentially stacked on the surface of the silicon substrate in the direction away from the silicon substrate, the bus bar grid line is arranged on the side of the first functional film away from the silicon substrate, the current collecting grid line forms ohmic contact with the doped layer through the first functional film; the overlap section forms ohmic contact with the doped layer through the first functional film; or, the overlap section is arranged on the side of the first functional film away from the silicon substrate; And / or, the bus bar grid line and the current collecting grid line are a plurality of, the plurality of bus bar grid lines are arranged at intervals along the second direction, the plurality of current collecting grid lines are arranged at intervals along the first direction, each current collecting grid line extends along the second direction, and each bus bar grid line intersects with the plurality of current collecting grid lines; the intersection of each current collecting grid line and each bus bar grid line is provided with the overlap section.

12. A photovoltaic module, characterized by A solar cell module comprising a plurality of electrically connected solar cells, at least one of the solar cells being a solar cell according to any one of claims 1 to 11.

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