Solar cells, screen plate structures, and photovoltaic modules

Abstract

The present invention discloses a solar cell, a screen plate structure, and a photovoltaic module. The solar cell includes a semi-finished solar cell and a first electrode, the first electrode including a plurality of first fingers and a plurality of first connectors, the plurality of first fingers being spaced apart along a first direction, each first finger extending along a second direction, the plurality of first connectors being spaced apart along the first direction, the first connectors being connected to the first fingers, and some of the first connectors being welded to a solder ribbon. The maximum height H1 of the first connectors satisfies 4 μm ≤ H1 ≤ 10 μm. [Effects] The solar cell, screen plate structure, and photovoltaic power generation module according to the present invention can reduce the production defect rate of solar cells, improve the performance of solar cells, and reduce production costs.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and particularly to solar cells, screen structures, and solar power generation modules.

Background Art

[0002] With the development of solar power generation technology, the development of high-efficiency and low-cost solar cells and modules has always been the focus of constant research in the solar power generation industry. Achieving the goal of reducing the consumption of paste and thus reducing costs is the development trend of the solar power generation industry.

[0003] In related technologies, usually, the width and height of the fingers are reduced to reduce the consumption of paste. However, due to the limitations of the screen process, it is impossible to effectively achieve both the miniaturization of the electrodes' fingers and good performance. And when the height of the fingers becomes small, the contact resistivity at the finger contact points of the solar cell increases, which is disadvantageous for improving the conversion efficiency of the solar cell, and finger breakage defects are likely to occur during welding.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Embodiments of the present invention disclose a solar cell, a screen plate structure, and a solar power generation module, which can reduce the production defect rate of the solar cell, improve the performance of the solar cell, and also reduce the production cost.

Means for Solving the Problems

[0005] To achieve the above object, as a first aspect, embodiments of the present invention disclose a solar cell, which includes a semi-finished solar cell and a first electrode, The first electrode is provided on the semi-finished solar cell and includes a plurality of first fingers and a plurality of first connecting parts, the plurality of first fingers are spaced apart along a first direction and each of the first fingers extends along a second direction, the plurality of first connecting parts are spaced apart along the first direction and the first connecting parts are connected to the first fingers and some of the first connecting parts are welded to a solder ribbon. The maximum height H1 of the first connection satisfies 4 μm ≤ H1 ≤ 10 μm, and the first direction and the second direction intersect.

[0006] In one optional embodiment, in an embodiment of the first aspect of the present invention, the smoothing factor of the first finger is smaller than the smoothing factor of the first connection.

[0007] As one selectable embodiment, in an embodiment of a first aspect of the present invention, the first electrode further includes a plurality of first busbars, the plurality of first busbars spaced apart along the second direction, each first busbar extending along the first direction, and the first busbars intersecting the first connection, Of these, the maximum height H1 of the first connection portion is greater than the maximum height of the first busbar corresponding to the first connection portion.

[0008] As one selectable embodiment, in an embodiment of the first aspect of the present invention, the maximum height of the first finger connected to the first connector is H2, where H1 ≥ 1.2H2 to 3H2.

[0009] As one selectable embodiment, in an embodiment of the first aspect of the present invention, the maximum height of the first finger connected to the first connector is H2, and the difference between H1 and H2 is in the range of 1 μm to 4 μm.

[0010] As one selectable embodiment, in an embodiment of the first aspect of the present invention, the maximum height H2 of the first finger connected to the first connector satisfies 4 μm ≤ H2 ≤ 6 μm.

[0011] As one selectable embodiment, in an embodiment of a first aspect of the present invention, the solar cell further includes a second electrode provided on the semi-finished solar cell, comprising a plurality of second fingers and a plurality of second connectors, wherein the plurality of second fingers are spaced apart along a first direction, each second finger extends along a second direction, the plurality of second connectors are spaced apart along the first direction, the second connectors are connected to the second fingers, and some of the second connectors are welded to a solder ribbon. The maximum height of the second connection is H3, and H1 > H3.

[0012] As one selectable embodiment, in an embodiment of the first aspect of the present invention, the maximum height H3 of the second connection satisfies 4 μm ≤ H3 ≤ 8 μm.

[0013] As one optional embodiment, in an embodiment of the first aspect of the present invention, the polarity of the first electrode and the polarity of the second electrode are opposite, The first electrode is provided on the front of the semi-finished solar cell and the second electrode is provided on the back of the semi-finished solar cell, or both the first electrode and the second electrode are provided on the back of the semi-finished solar cell.

[0014] In one selectable embodiment, in an embodiment of the first aspect of the present invention, the first connection includes a finger connection wire and a busbar connection wire, wherein the finger connection wire overlaps with at least a portion of the busbar connection wire.

[0015] In one optional embodiment, in an embodiment of the first aspect of the present invention, a silicon-containing dielectric layer is provided in the corresponding region between the busbar connection line and the semi-finished solar cell.

[0016] In one optional embodiment, in a first aspect embodiment of the present invention, the busbar connection wire covers the finger connection wire.

[0017] As one selectable embodiment, in a first aspect embodiment of the present invention, the total length L1 of the busbar connection wire and / or the finger connection wire in the second direction is 1 mm to 1.5 mm. And / or, the minimum width W1 of the busbar connection wire and / or the finger connection wire in the first direction is 10 μm to 20 μm. and / or, the maximum width W2 of the busbar connection line in the first direction is 50 μm to 80 μm. And / or, the maximum width W3 of the finger connection wire in the first direction is 25 μm to 40 μm.

[0018] As a second aspect, the present invention discloses a screen plate structure applicable to a solar cell, wherein the solar cell includes a semi-finished solar cell, the screen plate structure includes a substrate, the substrate includes a main body and a thickened portion, the thickened portion is provided on the main body along the thickness direction of the main body, the main body has a plurality of first grooves that penetrate along its own thickness direction, the plurality of first grooves are spaced apart along a first direction, each of the first grooves extends along a second direction, and the first grooves are configured for forming first fingers on the semi-finished solar cell. The thickened portion has a second groove extending along the second direction, the second groove corresponds to at least one of the first grooves and penetrates the main body along the thickness direction of the main body and communicates with the first groove, the second groove is configured to connect a first connection portion formed on the semi-finished solar cell to the first finger, and the first connection portion is configured to connect to a solder ribbon. Eventually, the first direction and the second direction intersect.

[0019] In one selectable embodiment, in a second aspect embodiment of the present invention, each of the first grooves includes a plurality of sub-grooves spaced apart along the second direction, the thickened portion is located between at least two adjacent sub-grooves, and the second groove connects two adjacent sub-grooves.

[0020] As one selectable embodiment, in the example of the second aspect of the present invention, the thickness H4 of the thickening portion is 1 μm to 3 μm.

[0021] As one selectable embodiment, in the example of the second aspect of the present invention, the opening depth H5 of the first grooving is 4 μm to 10 μm.

[0022] As a third aspect, the present invention further discloses a photovoltaic module, and the photovoltaic module includes the solar cell described in the first aspect above, or a solar cell manufactured by the screen plate structure described in the second aspect above.

Advantages of the Invention

[0023] [[ID=[]] Compared with the prior art, the beneficial effects of the present invention are as follows. [[ID=[]] [[ID=[]]

[0024] [[ID=[]] [[ID=[]] The present invention discloses a solar cell, a screen plate structure and a photovoltaic module. The first electrode includes a plurality of first fingers and a plurality of first connection parts. Some of the first connection parts are provided to be welded to a solder ribbon. The maximum height of the first connection part is H1, and 4 μm ≤ H1 ≤ 10 μm. During welding, the tin-based alloy on the surface of the solder ribbon reacts with the first connection part, and the tin-based alloy therein etches a certain amount of conductive metal material in the first connection part to form a conductive metal-tin-lead alloy system. When the height of the conductive metal material in the first connection part is low, a sufficient amount of conductive metal material cannot be provided due to the welded conductive metal-tin-lead alloy system. As a result, the current collected by the first fingers of the solar cell cannot be transmitted by the solder ribbon, that is, a problem of finger breakage occurs between the first fingers and the solder ribbon. Therefore, by setting the maximum height H1 of the first connection part within the above range, it is advantageous to reduce the probability of problems such as finger breakage, and the reasonable height range can avoid the contact resistivity at the connection location between the first finger and the first connection part from being too large, which is more advantageous for improving the conversion efficiency of the solar cell. [[ID=[]]

[0025] [[ID=[]] At the same time, by controlling the maximum height of the first connection section to an optimal height range, the consumption of printing paste in the first connection section can be reduced, which is advantageous for better controlling the production costs of solar cells. [Brief explanation of the drawing]

[0026] To more clearly illustrate the technical aspects of the embodiments of the present invention, the drawings that need to be used in the embodiments will be briefly described below. However, the drawings described below represent only a few embodiments of the present invention, and it will be obvious to those skilled in the art that other drawings can be obtained based on these drawings without any creative effort.

[0027] [Figure 1] This is a schematic diagram of the structure of the first electrode of the solar cell according to the present invention. [Figure 2] This is an enlarged schematic diagram of area A in Figure 1. [Figure 3] This is a schematic diagram of the cross-sectional structure of the first connecting portion and the first finger according to the present invention. [Figure 4] This is a schematic diagram of the structure of the second electrode of the solar cell according to the present invention. [Figure 5] This is an enlarged schematic diagram of area B in Figure 4. [Figure 6] This is a schematic diagram of the cross-sectional structure of the first and second connecting parts according to the present invention. [Figure 7] This is a cross-sectional contour view of the first connecting portion according to the present invention. [Figure 8] This is a cross-sectional contour view of the second connecting portion according to the present invention. [Figure 9] This is a magnified schematic diagram of area C in Figure 2. [Figure 10] This is a magnified schematic diagram of location D in Figure 5. [Figure 11] This document demonstrates how to calculate the smoothing factor in this invention based on a morphological diagram of a finger captured with a 3D microscope. [Figure 12] This is a schematic diagram of the screen plate structure according to the present invention. [Figure 13]This is a schematic diagram of a screen plate structure according to the present invention, which has a reinforcing structure. [Figure 14] This is a magnified schematic diagram of location E in Figure 13. [Figure 15] This is a schematic diagram of the structure of a screen plate structure having a reinforcing structure but without a thickened section, according to the present invention. [Figure 16] This is a cross-sectional view of the screen plate structure according to the present invention. [Modes for carrying out the invention]

[0028] The technical concepts in the embodiments of the present invention will be described clearly and completely below with reference to the drawings of the embodiments of the present invention, and it will be clear that the embodiments described are only a selection of embodiments of the present invention, and not all embodiments. All other embodiments that can be obtained by those skilled in the art without creative work based on the embodiments of the present invention are within the scope of the protection of the present invention.

[0029] In this invention, directions or positional relationships indicated by terms such as "up," "down," "left," "right," "front," "back," "top," "bottom," "inside," "outside," "vertical," "horizontal," "lateral," and "vertical" are based on the directions or positional relationships shown in the drawings. These terms are primarily used to better describe the invention and its embodiments, but are not intended to limit the devices, elements, or components mentioned to having a specific orientation or being configured and operated in a specific orientation.

[0030] Furthermore, some of the above terms may be used to express meanings other than those used to express direction or positional relationships. For example, the term "above" may, in some cases, be used to express a dependency or connection relationship. Those skilled in the art will understand the specific meaning of these terms in this invention depending on the specific context.

[0031] Furthermore, the terms "attach," "install," "be installed," "connect," and "be linked" should be understood in a broad sense. For example, it may be a fixed connection, a removable connection, a one-piece structure, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate mediator, or an internal communication between two devices, elements, or components. Those skilled in the art will understand the specific meaning of the above terms in this invention depending on the specific situation.

[0032] Furthermore, the terms "first" and "second" are primarily used to distinguish between different devices, elements, or components (whether of the same or different specific types or structures), and do not indicate or imply the relative importance or number of the devices, elements, or components mentioned. Unless otherwise specified, "plural" means two or more.

[0033] With the advancement of solar power technology, the development of high-efficiency, low-cost solar cells and modules has always been a constant research focus in the solar power industry. Considering the performance of solar cells while also reducing paste consumption to achieve cost reductions is a developmental trend in the solar power industry.

[0034] In related technologies, the width and height of the fingers are usually reduced to decrease paste consumption. However, due to limitations in the screen process, miniaturization of the electrode fingers and good performance cannot be effectively achieved simultaneously. Furthermore, the inventors have found that reducing the height of the electrode wires increases the contact resistivity at the finger locations of the solar cell, which is detrimental to improving the conversion efficiency of the solar cell. In addition, it makes the fingers more prone to breakage during welding of the solar cell, making it impossible to meet the welding requirements for the electrodes.

[0035] Specifically, the related steel wire mesh screen technology has limitations in compressing the groove width of the film layer. Even if the grooves are designed to narrow the wire width, the paste gets clogged due to entanglement in the steel wire mesh screen, affecting its discharge and thus the printed fingers, preventing the true realization of finely wired battery electrodes. At the same time, attempting to reduce the overall amount of silver paste used by compressing the finger height also causes problems. That is, the electrode height during welding does not meet the requirements for good welding. When welding the solder ribbon, the height of the fingers being welded is too small. When the tin alloy on the surface of the solder ribbon reacts with the silver electrode fingers, the silver content in the silver fingers does not meet the requirement for sufficient welding of the solder ribbon. As a result, defects such as finger breakage at the welded point occur, affecting the solder ribbon's ability to collect current. Furthermore, if the finger height is too small, the cross-sectional area of ​​the fingers becomes small, resulting in excessively high contact resistivity, which affects the conversion efficiency of the solar cell, making it impossible to comprehensively achieve the effects of high efficiency and low cost.

[0036] Based on this, the present invention proposes a solar cell, a screen plate structure, and a photovoltaic power generation module. The first electrode includes a plurality of first fingers and a plurality of first connection parts, some of which are used for welding to a solder ribbon, the maximum height of the first connection part is H1, and 4μm ≤ H1 ≤ 10μm. Setting the maximum height of the first connection part of the first electrode within a reasonable range is advantageous not only in reducing the probability of defects such as finger fracture due to welding, but also in avoiding excessively high contact resistivity at the contact point between the first finger and the first connection part, thereby improving the conversion efficiency of the solar cell. At the same time, controlling the maximum height of the first connection part within an optimal height range reduces the consumption of printing paste for the first connection part, which is advantageous in better controlling the production cost of the solar cell.

[0037] The technical proposal of the present invention will be further described below in conjunction with examples and drawings.

[0038] Referring to Figures 1 to 4 as the first aspect, an embodiment of the present invention discloses a solar cell 100. This solar cell 100 includes a semi-finished solar cell 10, which has a front surface 10a and a back surface 10b that are facing away from each other. Of these, the front surface 10a of the semi-finished solar cell 10 is a light-receiving surface, and the back surface 10b of the semi-finished solar cell 10 is a non-light-receiving surface.

[0039] The semi-finished solar cell 10 may be a semi-finished structure in which electrodes have not yet been printed on the solar cell 100. For example, this semi-finished solar cell 10 may include a silicon base, a front passivation layer and a front anti-reflective layer sequentially formed on the front surface of the silicon base, and a back passivation layer and a back anti-reflective layer sequentially formed on the back surface of the silicon base.

[0040] In some embodiments, referring to Figures 1 and 2, the solar cell 100 includes a first electrode 20, which is provided on a semi-finished solar cell 10, and the first electrode 20 includes a plurality of first fingers 21 and a plurality of first connectors 22, the plurality of first fingers 21 are spaced apart along a first direction X, each first finger 21 extends along a second direction Y, the plurality of first connectors 22 are spaced apart along the first direction X, the first connectors 22 are connected to the first fingers 21, and some of the first connectors 22 are welded to solder ribbon (not shown).

[0041] In embodiments of the present invention, the first direction X and the second direction Y intersect. For example, the first direction X is perpendicular or approximately perpendicular to the second direction Y. For example, the first direction X may be the vertical direction and the second direction Y may be the horizontal direction, and the plurality of first fingers 21 are provided spaced apart along the vertical direction, and each first finger 21 extends along the horizontal direction. Among these, the plurality of first fingers 21 are parallel or approximately parallel to each other. In the actual manufacturing process of the solar cell 100, process factors such as equipment precision and measurement errors affect the actual molding effect of the fingers, so it can be understood that the fingers will be approximately parallel to each other.

[0042] During welding, the tin alloy on the surface of the solder ribbon reacts with the first connection part 22, causing a certain amount of conductive metal material in the first connection part 22 to be etched by the tin alloy, thereby forming a conductive metal-tin alloy system. If the height of the conductive metal material in the first connection part 22 is low, it is not possible to provide a sufficiently large amount of conductive metal material for the welded conductive metal-tin alloy system. As a result, the current collected by the first finger 21 of the solar cell cannot be transmitted through the solder ribbon, which means that a finger break occurs between the first finger 21 and the solder ribbon.

[0043] Of these, the conductive metal in the first connection portion 22 is intended to transmit electric current and connect the fingers, busbars, and solder ribbons to each other. Therefore, the conductive metal for forming the first connection portion 22 of the present invention is not limited to commonly seen silver paste, silver-aluminum paste, aluminum paste, electroplated copper, or silver-coated copper paste.

[0044] Based on this, in some embodiments, the maximum height H1 of the first connection portion 22 satisfies 4μm ≤ H1 ≤ 10μm. Selectively, the maximum height H1 of the first connection portion 22 can satisfy 4μm ≤ H1 ≤ 5μm, 5μm ≤ H1 ≤ 6μm, 6μm ≤ H1 ≤ 7μm, 6μm ≤ H1 ≤ 8μm, 7μm ≤ H1 ≤ 8μm, or 7μm ≤ H1 ≤ 10μm, etc. For example, H1 may be 6μm, 7μm, 8μm, 9μm, or 10μm, etc.

[0045] By setting the maximum height H1 of the first connection part 22 within the above range, it is advantageous to reduce the probability of malfunctions such as finger breakage due to welding, and the reasonable height range avoids the contact resistance at the contact point between the first finger 21 and the first connection part 22 being too high, which is advantageous in improving the conversion efficiency of the solar cell 100 and the reliability of the photovoltaic power generation module.

[0046] At the same time, by controlling the maximum height H1 of the first connection part 22 to an optimal height range, the consumption of printing paste in the first connection part 22 can be reduced, which is advantageous for better controlling the production cost of the solar cell 100.

[0047] If the maximum height H1 of the first connection portion 22 is less than 4 μm, the maximum height H1 of the first connection portion 22 is too low. During welding of the solder ribbon and the first connection portion 22, the tin alloy in the solder ribbon undergoes a silver etching reaction with the first connection portion 22. The excessively low first connection portion 22 cannot meet the conductivity requirements and welding reliability requirements for welding with the solder ribbon. As a result, welding fracture occurs between the solder ribbon and the first connection portion 22, preventing current transmission and causing serious defects in the solar cell 100. If the maximum height H1 of the first connection portion 22 is greater than 10 μm, the maximum height H1 of the first connection portion 22 is too high. While this meets the welding height requirement and reduces the probability of finger breakage, it increases the consumption of printing paste, which is detrimental to controlling the production cost of the solar cell 100.

[0048] The maximum height H1 of the first connection portion 22 in this invention can be defined as follows. A 3D microscope is used to obtain the height contour of the first connection portion 22, and an appropriate region of the first connection portion 22 is selected along the extension direction of the first connection portion 22 and set as a reference line for the height contour. The reference line is measured and the height point value of the reference line is derived. For example, in this invention, 1024 height point values ​​are derived, and then data cleaning is performed on these 1024 height point values ​​to remove abnormal data points. After that, the top 100 highest height point values ​​are selected from the remaining height point values ​​and their average value is calculated. The calculated value is the maximum height H1 of the first connection portion 22 as defined in this invention. Among these, abnormal data points are defined as height point values ​​that exceed the average value of the height point values ​​by 30%. For example, assuming that the average value of the 1024 height point values ​​is Xave and the abnormal data point is Xi, then a height value where |Xi-Xave| / Xave>30% belongs to the abnormal height point values ​​described in this invention. If the length of the first connection portion 22 is too long at the microscope's magnification, only the height point value of the first connection portion 22 on any one side of the busbar can be tested. The number of height point values ​​to be derived will also vary depending on the processing software used to test the height point values.

[0049] It can be understood that the solar cell 100 in the embodiment of the present invention may be 0BB (Zero Busbar, no busbar). When the solar cell 100 is 0BB, the busbar or pads on the busbar are canceled, and the first connection part 22 is welded to the solder ribbon, so that the current is collected and led out directly by the solder ribbon. In this way, the amount of paste consumed for the busbar on the surface of the semi-finished solar cell 10 can be significantly reduced, and the objective of cost reduction can be achieved.

[0050] Of course, in other embodiments, the solar cell 100 of the present invention may be an MBB (Multi Busbar), SMBB (Super Multi Busbar), or the like.

[0051] In some embodiments, referring to Figure 2, the first electrode 20 further includes a plurality of first busbars 23, the plurality of first busbars 23 spaced apart along a second direction Y, each first busbar 23 extending along a first direction X, and the first busbars 23 intersect with a first connection portion 22. That is, the first connection portion 22 is located at the intersection of the first busbars 23 and the first finger 21.

[0052] By providing a first busbar 23 on the semi-finished solar cell 10, the current collected by the first finger 21 is collected in the first busbar 23, and the current is further extracted by welding the first connection part 22 to the solder ribbon. The first connection part 22 effectively ensures the welding area between the solder ribbon and the first busbar 23 and / or the pad located on the first busbar 23, thereby improving the pull-out force requirement for the solder ribbon.

[0053] In some embodiments, the maximum height H1 of the first connection portion 22 is greater than the maximum height of the first busbar 23 corresponding to the first connection portion 22. By setting the maximum height H1 of the first connection portion 22 to be greater than the maximum height of the first busbar 23 in the corresponding region, the maximum height H1 of the first connection portion 22 after welding to the solder ribbon can be reduced, provided that the current collected by the first busbar 23 can be transmitted by the solder ribbon, thereby achieving the objective of reducing production costs.

[0054] In this invention, the maximum height of the first busbar 23 can be determined by referring to the definition of the maximum height H1 of the first connection portion 22 described above. However, considering the screen design in this invention, the height of the busbar corresponding to the intersection of the first finger 21 and the first busbar 23 increases due to the presence of the thickened portion 202. Therefore, in this invention, the region for measuring the maximum height of the first busbar 23 is defined as the busbar region not covered by any busbar connection line 221. Furthermore, considering that the design width of the busbar is usually smaller than the length of the first connection portion 22, the busbar region corresponding to the measurement region of the maximum height of the first connection portion 22 can be used as the selection center for the reference line of the height contour, and the distribution region of the maximum height of the first busbar 23 along a direction parallel to the extension direction of the busbar can be selected as the reference line of the contour to be measured.

[0055] Selectively, the number of first busbars 23 can be between 16 and 26. For example, the number of first busbars 23 can be 16, 18, 22, or 24. In this way, a larger number of first busbars 23 can be obtained with smaller spacing, reducing the distance between two adjacent first busbars 23 and thus reducing the transmission resistance of the fingers and lowering the series resistance, which is advantageous for improving photoelectric conversion efficiency.

[0056] In some embodiments, referring to Figure 3, Figure 3 shows a schematic cross-sectional view of the first connecting portion 22 and the first finger 21 connected to the first connecting portion 22. Let H2 be the maximum height of the first finger 21 connected to the first connecting portion 22, and set H1 ≥ 1.2H2 to 3H2. That is, the maximum height H1 of the first connecting portion 22 may be 1.2 to 3 times the maximum height of the first finger 21 connected to it, or the maximum height H1 of the first connecting portion 22 may be greater than 1.2 to 3 times the maximum height of the first finger 21 connected to it.

[0057] Selectively, the relationship between H1 and H2 may be H1≧1.2H2, H1≧1.5H2, H1≧2H2, or H1≧3H2, etc. For example, H1=1.5H2, H1=2H2, H1=2.5H2, or H1=3H2, etc.

[0058] By setting the maximum height H1 of the first connection portion 22 to be greater than or equal to the maximum height of the first finger 21 connected thereto, that is, by appropriately increasing the height of the welding area of ​​the first electrode 20, the electrode configuration is made in which the first finger 21 has a relatively low height and the welding area has a relatively high height. This reduces the risk of finger breakage due to welding caused by the welding area being too low during solder ribbon welding, thereby reducing the production defect rate of the solar cell 100. At the same time, controlling the maximum height of the first finger 21 within a reasonable height range also achieves the objective of reducing paste consumption, which is advantageous in reducing the production cost of the solar cell 100.

[0059] In the following, the solar cell 100 of the present invention was used as the experimental group, and solar cells of related technologies were used as the control group. Tests were conducted mainly based on the height of the busbars, the height of the fingers, the difference in height between the two, and the conversion efficiency, and the parameters shown in Table 1 were obtained.

[0060] [Table 1]

[0061] As can be seen from the test data in Table 1, the solar cell in the embodiment of the present invention can maintain a conversion efficiency almost equivalent to that of solar cells in related technologies, even when the finger height is reduced. In other words, by controlling the finger height within a reasonable range, the solar cell of the present invention reduces the amount of paste consumed and achieves cost reduction, while also avoiding a decrease in conversion efficiency due to excessively high contact resistance caused by the low finger height. At the same time, since the experimental group used a steel plate screen to print the fingers, it is possible to form fingers with a smaller smoothing factor, providing lower resistance transmission loss for current transmission. As can be seen from this, the solar cell 100 in the embodiment of the present invention can comprehensively achieve the effect of cost reduction.

[0062] The first electrode 20 includes a plurality of first fingers 21 and a plurality of first connecting portions 22, where the first fingers 21 and the first connecting portions 22 are provided in correspondence, that is, each first finger 21 is provided with a plurality of first connecting portions 22, and these first connecting portions 22 are provided at intervals along the second direction Y. In this way, H1 is the maximum height of the first connecting portion 22 connected to the first finger 21, and H2 is the maximum height of each first finger 21. Of these, a portion of the first fingers 21 close to the first connecting portions 22 can be selected as the measurement range for the maximum height H2 of the first fingers 21 connected to the first connecting portions 22. A 3D microscope is used to obtain the height contour of the first finger 21, and along the extension direction of the first finger 21, an appropriate region of the first finger 21 is taken as a reference line for the height contour, the reference line is measured, and the height point value of the reference line is derived. For example, in this invention, 1024 height point values ​​are derived, and then data cleaning is performed on these 1024 height point values ​​to remove anomalous data points. After that, the largest of the previous 100 points is selected from the remaining points, their average value is calculated, and this is taken as the maximum height H2 of the first finger 21. Among these, anomalous data points are defined as height point values ​​that exceed the average value of the height point values ​​by 30%. For example, assuming that the average value of the 1024 height point values ​​is Xave and the anomalous data point is Xi, then a height point value where |Xi-Xave| / Xave>30% belongs to the anomalous height point values ​​described in this invention.

[0063] In some embodiments, the difference between H1 and H2 is in the range of 1 μm to 4 μm. Selectively, the height difference between H1 and H2 may be 1 μm to 3 μm, 1 μm to 2 μm, 2 μm to 4 μm, or 2 μm to 3 μm, etc. For example, the height difference between H1 and H2 may be 1 μm, 2 μm, 3 μm, or 4 μm, etc.

[0064] By limiting the maximum height H1 of the first connection portion 22 to be greater than the maximum height of the first finger 21, and keeping the height difference between the two within a reasonable range, it is possible to satisfy the welding performance requirements and save paste, while ensuring that the height difference between the first connection portion 22 and the first finger 21 is not too large, thereby avoiding the problem of cracks occurring due to welding caused by an excessive height difference.

[0065] If the height difference between H1 and H2 is less than 1 μm, and the height difference between them is not large, the maximum height H1 of the first connection part 22 will not meet the requirement of a certain height, making it impossible to avoid the problem of finger fracture due to welding. This leads to an increase in the amount of paste used to print the first finger 21, which is unfavorable to reducing paste consumption. If the height difference between H1 and H2 is greater than 4 μm, it means that the height of the first finger 21 is relatively low, and a relatively low height of the first finger 21 leads to the first finger 21 having a relatively high resistivity for collecting current, which cannot meet the high requirements for the conversion efficiency of solar cells 100 in the current market. Also, if the printing height of the first finger 21 is too low, it may not be possible to fill it with screen printing, meaning that the thickness of the screen plate must be reduced to achieve a relatively low printing height of the first finger, but a screen plate printing thickness that is too low may not be achievable with the manufacturing capacity of the current process.

[0066] In some embodiments, the maximum height H2 of the first finger 21 connected to the first connection portion 22 satisfies 4 μm ≤ H2 ≤ 6 μm. Selectively, the height H2 of the first finger 21 connected to the first connection portion 22 can satisfy 4 μm ≤ H2 ≤ 5 μm, 5 μm ≤ H2 ≤ 6 μm, or 4.5 μm ≤ H2 ≤ 5.5 μm, etc. For example, H2 may be 4 μm, 5 μm, or 6 μm, etc.

[0067] By limiting the maximum height H2 of the first finger 21 to a reasonable range, a height difference is created between it and the first connection part 22. This reduces the height of the first finger 21, thereby achieving the objective of reducing the overall paste consumption. Furthermore, it avoids the problem of welding defect rates caused by the reduction in the height of the first finger 21, thus comprehensively meeting market demands for high efficiency and low cost in solar cells. In addition, by controlling the maximum height of the first finger 21 to a reasonable range, the first finger 21 can be made to have better current transmission capability. If the height of the first finger 21 is too low, the contact resistance and line resistance of the first finger 21 increase, ultimately increasing the current transmission loss of the solar cell 100. Also, if the printing height of the first finger 21 is too low, it cannot be filled by screen printing, meaning that the thickness of the screen plate must be reduced to achieve a relatively low printing height of the first finger. However, a screen plate printing thickness that is too low may not be achievable with the current process manufacturing capacity. If the maximum height of the first finger 21 is too high, the consumption of printing paste for the first finger increases, which is detrimental to controlling production costs. Furthermore, due to the flow form of the paste, the printed finger diffuses into the normal light-irradiated area of ​​the battery sheet, reducing the effective area for generating photovoltaic current in the solar cell and decreasing the conversion efficiency of the solar cell.

[0068] In some embodiments, referring to Figures 4 and 5, the solar cell 100 includes a second electrode 30, which is provided on a semi-finished solar cell 10, and the second electrode 30 includes a plurality of second fingers 31 and a plurality of second connectors 32, the plurality of second fingers 31 are spaced apart along a first direction X, each second finger 31 extends along a second direction Y, the plurality of second connectors 32 are spaced apart along the first direction X, the second connectors 32 are connected to the second fingers 31, and some of the second connectors 32 are welded to a solder ribbon.

[0069] Selectively, multiple second fingers 31 may be provided at intervals along the longitudinal direction, and each may extend along the transverse direction.

[0070] In some embodiments, the second electrode 30 may further include a plurality of second busbars 33, which are spaced apart along a second direction Y, each second busbar 33 extending along a first direction X, and intersecting with a second connector 32. That is, the second connector 32 is located at the intersection of the second busbar 33 and the second finger 31. The specific installation method can be found in the installation of the first busbar 23 in the first electrode 20, which will not be described again here.

[0071] In some embodiments, the polarity of the first electrode 20 and the polarity of the second electrode 30 are opposite. For example, the first electrode 20 may be the positive electrode and the second electrode 30 may be the negative electrode, or the first electrode 20 may be the negative electrode and the second electrode 30 may be the positive electrode.

[0072] Selectively, the first electrode 20 is provided on the front surface 10a of the semi-finished solar cell 10, and the second electrode 30 is provided on the back surface 10b of the semi-finished solar cell 10. Alternatively, in the structural design of a back-contact solar cell, both the first electrode 20 and the second electrode 30 are provided on the back surface 10b of the semi-finished solar cell 10.

[0073] Furthermore, a solar cell 100 in which the first electrode 20 is provided on the front surface 10a of the semi-finished solar cell 10 and the second electrode 30 is provided on the back surface 10b of the semi-finished solar cell 10 may be a passivation contact cell, and a solar cell 100 in which both the first electrode 20 and the second electrode 30 are provided on the back surface 10b of the semi-finished solar cell 10 may be a back contact cell. In other words, by eliminating the shielding of light rays by the front surface fingers, current loss due to light shielding can be avoided.

[0074] In an embodiment of the present invention, the first electrode 20 is provided on the front surface 10a of the semi-finished solar cell 10, and the second electrode 30 is provided on the back surface 10b of the semi-finished solar cell 10.

[0075] In actual production, the inventors found that when the first electrode 20 is provided on the front surface 10a of the semi-finished solar cell 10 and the second electrode 30 is provided on the back surface 10b of the semi-finished solar cell 10, the glass powder content in the paste for printing the busbars of the first and second electrodes is usually the same, but the glass powder content in the paste for printing the second finger 31 on the back surface 10b is usually greater than the glass powder content in the paste for printing the first finger 21 on the front surface 10a. In other words, the glass powder content in the paste for printing the first connector 22 is configured to be less than the glass powder content in the paste for printing the second connector 32.

[0076] The inventor's research revealed that the glass powder content in the paste used for printing the back fingers of the solar cell is higher than that in the paste used for the front fingers. This glass powder interferes with the reaction between the tin alloy in the solder ribbon and the silver in the fingers, thereby preventing the fingers from melting.

[0077] In some embodiments, the maximum height of the second connection portion 32 is H3, and H1 > H3. In other words, the maximum height of the first connection portion 22 is greater than the maximum height of the second connection portion 32.

[0078] Furthermore, since the solar cell 100 has a plurality of first connection parts 22 and a plurality of second connection parts 32, the statement above that the maximum height of the first connection part 22 is greater than the maximum height of the second connection part 32 means that the maximum height of the first connection part 22 in any first electrode 20 is greater than the maximum height of the second connection part 32 in any second electrode 30.

[0079] Referring to Figure 6, Figure 6 shows a schematic cross-sectional view of the first connection portion 22 and the second connection portion 32, with the first electrode 20 and the second electrode 30 being provided on the front and back of the semi-finished solar cell 10, respectively. In this drawing, two groups of the first connection portion 22 and the second connection portion 32 are shown, facing away from each other in the thickness direction of the semi-finished solar cell 10. Of these, H1 > H3 may refer to the relationship between the maximum heights of the first connection portion 22 and the second connection portion 32 of one group (corresponding to the top and bottom of the page in Figure 6), or it may refer to the relationship between the maximum height of the first connection portion 22 of one group and the maximum height of the second connection portion 32 of another group (corresponding to the intersecting lines on the page in Figure 6).

[0080] Furthermore, the maximum height H1 of the first connection part 22 and the maximum height H3 of the second connection part 32 can satisfy the following conditions: H1 ≥ 1.2H3, H1 ≥ 1.4H3, H1 ≥ 1.5H3, or H1 ≥ 1.75H3. For example, H1 = 1.2H3, H1 = 1.4H3, H1 = 1.5H3, or H1 = 1.75H3. For example, if the maximum height H1 of the first connection part 22 is 6 μm, the maximum height H3 of the second connection part 32 is 4 μm, and if the maximum height H1 of the first connection part 22 is 7 μm, the maximum height H3 of the second connection part 32 is 5 μm.

[0081] Since the glass powder content in the paste used to print the second finger 31 on the back surface 10b is usually greater than the glass powder content in the paste used to print the first finger 21 on the front surface 10a, the present invention sets the height of the first connection portion 22 of the first electrode 20 greater than the maximum height of the second connection portion 32 of the second electrode 30. This is because the relatively high glass powder content can prevent the second finger 31 of the second connection portion 32 from melting due to the silver etching reaction of the tin alloy on the surface of the solder ribbon during welding. In this way, the connection portion can be welded well even after undergoing the silver etching reaction of the solder ribbon, effectively ensuring that the current collected by the second finger 31 can be transmitted to the solder ribbon, thereby reducing the production defect rate of the solar cell 100 and reducing the amount of paste consumed when printing the second connection portion 32 of the second electrode 30. As can be seen from this, the present invention can prevent the melting and cutting of the second finger 31 of the second connection portion 32 during welding by utilizing a relatively high content of glass powder. In this way, the maximum height of the second connection portion 32 of the second electrode 30 can be set even lower than the height of the first connection portion 22 of the first electrode 20. This makes it possible to satisfy welding performance even without setting the second connection portion 32 of the second electrode 30 to the same height as the first connection portion 22, and at the same time saves on paste consumption and reduces production costs.

[0082] In this invention, the maximum height, such as the maximum height of the second connection part and the maximum height of the first finger, can all be defined by referring to the definition of the maximum height of the first connection part 22 in this invention. Regarding the selection of an appropriate region for the reference line of the height contour, referring to Figure 8, if the morphology of the first connection part is an M-shaped design with two peaks, the peak with the relatively high height can be used as the reference line for selecting the height contour, based on what is shown by a 3D microscope. If the morphology of the first connection part is a Gaussian curve shape with a single peak, the peak with the highest height can be used as the reference line for selecting the height contour.

[0083] In some embodiments, the maximum height H3 of the second connection portion 32 satisfies 4μm ≤ H3 ≤ 8μm. Selectively, the maximum height H3 of the second connection portion 32 can satisfy 4μm ≤ H3 ≤ 6μm, 4μm ≤ H3 ≤ 5μm, 5μm ≤ H3 ≤ 6μm, 6μm ≤ H3 ≤ 8μm, or 7μm ≤ H3 ≤ 8μm, etc. For example, H3 may be 4μm, 5μm, 6μm, 7μm, or 8μm, etc.

[0084] The glass powder content in the paste used to print the second finger 31 on the back surface 10b is usually higher than the glass powder content in the paste used to print the first finger 21 on the front surface 10a. Through research, the inventors have found that the glass powder can prevent the molten tin alloy in the solder ribbon from diffusing and reacting with silver, and that a relatively high glass powder content can prevent melting due to silver etching reaction between the molten tin alloy in the solder ribbon and the finger at the connection point during welding. Therefore, by limiting the maximum height H3 of the second connection point 32 to satisfy the above relation, the present invention can reduce the use of paste and lower production costs, assuming that the second connection point 32 of the second electrode 30 meets the welding height requirements. In other words, because the second connection point 32 of the second electrode 30 has a relatively high glass powder content, the welding requirements can be met without making the height of the second connection point 32 so high, achieving the objective of saving paste consumption and further enabling better control of the production costs of the solar cell.

[0085] The following will explain the differences in height between the first connection portion 22 of the first electrode 20 and the second connection portion 32 of the second electrode 30 of the present invention.

[0086] Referring to Figures 7 and 8, Figure 7 is a cross-sectional contour view of the first connection portion 22 of the first electrode 20 of the present invention at different positions, and Figure 8 is a cross-sectional contour view of the second connection portion 32 of the second electrode 30 of the present invention at different positions. In these cases, the cross-sectional contour view may be a cross-section taken along a plane parallel to the first direction.

[0087] Referring to Table 2, the comparison data of heights obtained by taking samples at three different positions of the first connection part 22 and the second connection part 32 are shown.

[0088] [Table 2]

[0089] Of these, the maximum heights obtained at three different positions of the first connection portion 22 of the first electrode 20 were 6.660 μm, 7.359 μm, and 6.779 μm, respectively, and the maximum heights obtained at three different positions of the second connection portion 32 of the second electrode 30 were 5.652 μm, 5.366 μm, and 5.360 μm, respectively. As can be seen from this, the maximum height of the first connection portion 22 of the first electrode 20 is greater than the height of the second connection portion 32 of the second electrode 30.

[0090] In some embodiments, referring to Figure 9, the first connection portion 22 includes a finger connection line 222 and a busbar connection line 221, with the finger connection line 222 overlapping with at least a portion of the busbar connection line 221. The finger connection line 222 may be the dotted line portion in Figure 9, and the busbar connection line 221 may be the solid line portion in Figure 9.

[0091] The first connection portion 22 can be formed by two printing passes, and by ensuring that the finger connection lines 222 and the busbar connection lines 221 overlap at least partially during printing, the height of the welding area is compensated, good welding alignment between the solder ribbon and the electrode fingers is achieved, the risk of finger breakage due to a low welding area is reduced, and the smoothness of the current transmission circuit is ensured. In this regard, the two printing passes required to manufacture the first connection portion 22 are necessary because both the finger screen plate and the busbar screen plate have corresponding printing areas for the first connection portion 22, thus enabling a thickened design for the maximum height of the first connection portion 22 through two printing passes.

[0092] Selectively, the busbar connection line 221 may be printed together with the first busbar 23, and the finger connection line 222 may be printed together with the first finger 21.

[0093] For example, a busbar connection line 221 is first printed on the semi-finished solar cell 10, and at this time, the height of the busbar connection line 221 may be about 3 μm to 4 μm. Then, a finger pattern is printed on the semi-finished solar cell 10, and the total height of the first connection part 22 where the finger connection lines 222 are superimposed is about 7 μm to 8 μm to satisfy the welding requirement.

[0094] In some embodiments, a silicon-containing dielectric layer is present in the corresponding region between the busbar connection wire 221 and the semi-finished solar cell 10. The presence of a silicon-containing dielectric layer in the corresponding region between the busbar connection wire 221 and the semi-finished solar cell 10 means that the busbar connection wire 221 does not fire through the silicon nitride on the surface of the semi-finished solar cell 10, and the paste used to print the busbar connection wire 221 is a non-fire-through conductive paste (e.g., a silver paste that does not contain or has a low content of glass powder). It can be understood that because non-fire-through conductive pastes have a low degree of corrosion, they do not destroy the silicon nitride film layer on the surface of the semi-finished solar cell 10, and thus reduce the failure of the PN junction of the solar cell 100.

[0095] In some embodiments, continuing with reference to Figure 9, the busbar connection wire 221 covers the finger connection wire 222. That is, the projection of the finger connection wire 222 on the semi-finished solar cell 10 falls within the projection range of the busbar connection wire 221 on the semi-finished solar cell 10, and the overall size of the busbar connection wire 221 is larger than the overall size of the finger connection wire 222.

[0096] By providing the busbar connection wire 221 to cover the finger connection wire 222, the area of ​​the overlapping first connection portion 22 can be made larger, which is advantageous in meeting welding requirements as a larger welding area also means a higher height.

[0097] Of course, in some other embodiments, the finger connectors 222 can cover the busbar connectors 221, i.e., the projection of the busbar connectors 221 onto the semi-finished solar cell 10 falls within the projection range of the finger connectors 222 onto the semi-finished solar cell 10.

[0098] In some embodiments, the total length of the busbar connection wire 221 in the second direction Y is the same as the total length of the finger connection wire 222 in the second direction Y, and / or the minimum width of the busbar connection wire 221 in the first direction X is the same as the minimum width of the finger connection wire 222 in the first direction X.

[0099] Based on the fact that the overall size of the busbar connection wire 221 is larger than that of the finger connection wire 222, and further limiting that the total length of the busbar connection wire 221 and the finger connection wire 222 are the same in the second direction Y and the minimum width is the same in the first direction X, the busbar connection wire 221 and the finger connection wire 222 can be made to have a more maximized overlap area. Even if there is some welding misalignment in the second direction Y during solder ribbon welding, the busbar connection wire 221 and the finger connection wire 222 both have a high overlap height along their total length in the second direction Y, so the welding requirements can be effectively met, and the phenomenon of finger breakage caused by molten tin cutting through the first finger 21 after welding can be effectively prevented.

[0100] In some embodiments, the total length L1 of the busbar connection wire 221 and the finger connection wire 222 in the second direction Y is 1 mm to 1.5 mm. Selectively, the total length L1 of the busbar connection wire 221 and the finger connection wire 222 in the second direction Y is 1 mm to 1.4 mm, 1 mm to 1.2 mm, or 1.2 mm to 1.5 mm, etc. For example, L1 may be 1 mm, 1.2 mm, 1.3 mm, 1.4 mm, or 1.5 mm, etc.

[0101] The total lengths of the busbar connection wire 221 and the finger connection wire 222 in the second direction Y may be the same, or the total length of the busbar connection wire 221 in the second direction Y may be greater than the total length of the finger connection wire 222 in the second direction Y. For example, if the total length of the busbar connection wire 221 in the second direction Y is 1 mm, the total length of the finger connection wire 222 in the second direction Y may also be 1 mm. Or, if the total length of the busbar connection wire 221 in the second direction Y is 1.5 mm, the total length of the finger connection wire 222 in the second direction Y may also be 1 mm.

[0102] In some embodiments, the minimum width W1 of the busbar connection wire 221 and / or finger connection wire 222 in the first direction X is 10 μm to 20 μm. Selectively, the minimum width W1 of the busbar connection wire 221 and / or finger connection wire 222 in the first direction X may be 10 μm to 17 μm, 10 μm to 15 μm, 15 μm to 20 μm, or 12 μm to 15 μm, etc. For example, W1 may be 10 μm, 13 μm, 15 μm, 17 μm, or 20 μm, etc.

[0103] In some embodiments, the maximum width W2 of the busbar connection wire 221 in the first direction X is 50 μm to 80 μm. Selectively, the maximum width W2 of the busbar connection wire 221 in the first direction X may be 50 μm to 70 μm, 50 μm to 60 μm, 60 μm to 80 μm, 70 μm to 80 μm, or 60 μm to 70 μm, etc. For example, W2 may be 50 μm, 60 μm, 70 μm, or 80 μm, etc.

[0104] In some embodiments, the maximum width W3 of the finger connection wire 222 in the first direction X is 25 μm to 40 μm. Selectively, the maximum width W3 of the finger connection wire 222 in the first direction X may be 25 μm to 35 μm, 25 μm to 30 μm, 30 μm to 40 μm, or 30 μm to 35 μm, etc. For example, W3 may be 25 μm, 30 μm, 35 μm, or 40 μm, etc.

[0105] By limiting the size of the busbar connection wires 221 and finger connection wires 222 to a reasonable range, a sufficient welding area is ensured to fill the welding space, preventing molten tin from cutting through the first finger 21 during welding and causing finger fracture. At the same time, paste consumption can be rationally allocated, the shading area can not be excessively increased, and the impact on the conversion efficiency of the solar cell 100 can be avoided.

[0106] Furthermore, the busbar connection wire 221 and the finger connection wire 222 have a shape that is approximately trapezoidal at both ends in the second direction Y and rectangular in the middle. That is, along the second direction Y, the width of the connection part in the first direction X gradually increases from both ends towards the middle, and when it reaches its maximum size, it exhibits a shape that does not change. In this way, the stability of the connection between the first finger 21 and the first busbar 23 is ensured, and breakage can be avoided. Moreover, the first connection part 22 has a large area to meet welding requirements, which is advantageous for current collection, maximizes the collection of conducted current, achieves the objective of reducing conduction resistance, and facilitates the provision of effective contact and stable current transmission. At the same time, by setting the size of the busbar connection wire 221 to a size that can cover the finger connection wire 222, it is possible to have a certain amount of slippage reserve when the finger connection wire 222 is within the range of the busbar connection wire 221, thereby avoiding situations in which the overall appearance of the first connection part 22 is poor.

[0107] Selectively, referring to Figure 10, the second connecting portion 32 may be a layer, and may not be printed in sync with the printing of the second finger 31.

[0108] As a second aspect, the present invention further discloses a screen plate structure 200. This screen plate structure 200 is applied to a solar cell 100, which includes a semi-finished solar cell 10. By utilizing this screen plate structure 200, a paste can be printed onto the surface of the semi-finished solar cell 10 according to a certain printing pattern by a printing process, and then sintered to form the first electrode 20 and / or second electrode 30 described above.

[0109] In related technologies, steel wire mesh screens are typically used for printing. Steel wire mesh screens are woven by interlacing wires of a certain number of meshes and wire diameters. Based on the selective paste permeability principle of the woven printing grooves, a screen plate with a specific pattern is created, and then printing is performed to form fixed patterned fingers on the semi-finished solar cell 10. Because the wires are connected alternately, the wires are not located on the same plane, and the alternating wires are shielded in the printing grooves. As a result, paste does not permeate easily during printing, the transfer rate is low, and the paste is printed unevenly, leading to problems such as finger breakage, ghosting, and poor flatness. Furthermore, the larger the aperture ratio of the screen mesh, the better the printability and the higher the degree of wire thinning. However, because steel wire mesh screens have mesh joints, the flatness of the fingers is limited. Furthermore, even if the current seamless mesh printing screen allows for pattern openings to be placed between two parallel meridians or parallel lines, improving paste permeability, a large number of meridians or parallel lines are still present in the pattern openings. These mesh lines perpendicular to the pattern still interfere with the printing of the silver paste, causing the printed fingers to still form height undulations. This increases the resistivity of the printed electrode pattern, reduces the effective utilization of the paste, and negatively impacts the power generation efficiency of the battery sheet.

[0110] In some embodiments, referring to Figure 12, the screen plate structure 200 includes a substrate 210, the substrate 210 includes a main body portion 201 and a thickened portion 202, the thickened portion 202 is provided on the main body portion 201 along the thickness direction of the main body portion 201, the main body portion 201 has a plurality of first open grooves 2011 that penetrate along its own thickness direction, the plurality of first open grooves 2011 are provided at intervals along a first direction X, each first open groove 2011 extends along a second direction Y, and the first open grooves 2011 are configured to form first fingers 21 on the semi-finished solar cell 10. A second groove 202a is formed in the thickened portion 202, extending along the second direction Y. The second groove 202a corresponds to at least one first groove 2011 and penetrates the main body portion 201 along the thickness direction of the main body portion 201, communicating with the first groove 2011. The second groove 202a is configured to form a first connection portion 22 on the semi-finished solar cell 10 and connect to the first finger 21, and the first connection portion 22 is configured to connect to the solder ribbon. In this configuration, the first direction X and the second direction Y intersect.

[0111] By providing a thickened portion 202 in the screen plate structure for printing the first finger 21, and creating a second groove 202a in the thickened portion 202 for forming the first connecting portion 22, it is possible to obtain more paste in the area after printing, thereby forming a first connecting portion 22 with a higher height, enabling the first connecting portion 22 to meet the welding height, ensuring that the tin alloy on the surface of the solder ribbon does not completely etch the silver in the welding area, thereby preventing the first finger 21 from being cut, and thus achieving good welding performance of the electrode.

[0112] Furthermore, both the first groove 2011 and the second groove 202a formed on the substrate 210 have a high opening ratio of 80% to 100% (including the 80% and 100% endpoints), and the opening ratio of the first groove 2011 is greater than that of the second groove 202a. When the first groove 2011 has an opening ratio of 100%, there is no shielding within the first groove 2011 for paste discharge. Compared to the related technology of steel wire mesh screens, where the openings are obstructed by wire or mesh joints, the grooves opened in the substrate 210 during printing allow the paste to pass through directly. This makes the paste transmission process smoother and more uniform, preventing printing defects such as disconnections and ghosting on the first finger 21, and avoiding situations where the printed paste becomes uneven due to shielding, resulting in a flatter printed finger. When the first groove 2011 has a high aperture ratio of 95% to 100% (excluding the 100% endpoint), sparse wires are provided in the first groove 2011 to strengthen the mechanical support strength of the substrate. Compared to the first groove 2011 with a 100% aperture ratio, the sparsely distributed wires interfere with the permeable paste and increase the unevenness of the fingers printed in the first groove 2011, but the effect is small, and the mechanical support strength of the substrate can be increased through the sparsely distributed wires. Therefore, when a screen plate is used in which sparsely distributed wires are provided in the first groove 2011, the smoothing factor of the printed first finger 21 is smaller than the smoothing factor of the first connection portion 22.

[0113] Specifically, referring to Figure 11, the height contour of the first finger 21 is measured using a 3D microscope at a magnification of 50 or other magnifications. Based on the height curve obtained by measuring the height contour, height point values ​​are derived from the height curve. For example, in this invention, 1024 height point values ​​are derived, and the concept of variance in mathematical statistics for these 1024 height point values ​​is calculated. The magnitude of the variation in the height of the first finger 21 is represented using this variance, which is the smoothing factor described in this invention. Note that any number of height point values ​​can be derived depending on the system settings of different models of 3D microscopes. In order to reduce the error influence of anomalous data points on the calculation of the smoothing factor, this invention requires the removal of anomalous height point values, of which anomalous data points are defined as height data point values ​​that exceed the average value of the height point values ​​by 30%. For example, assuming that the average value of the 1024 height point values ​​is Xave and the anomalous data point is Xi, then a height data point value where |Xi-Xave| / Xave>30% belongs to the anomalous height point value described in this invention.

[0114] Selectively, the substrate 210 may be a metal, alloy, or polymer material substrate 210 or base sheet. If the substrate 210 is a metal substrate 210, it may be, for example, a steel plate or a copper plate. If the substrate 210 is an alloy substrate 210, it may be, for example, a stainless steel plate or a nickel-cobalt-iron alloy plate. If the substrate 210 is a polymer material substrate 210, it may be, for example, a polyimide (PI) plate or a nylon base sheet.

[0115] Selectively, the screen plate structure 200 may further include a frame which is connected to the outer periphery of the substrate 210 and can be used to secure the substrate 210.

[0116] In some embodiments, referring to Figures 12 and 13, each first groove 2011 includes a plurality of sub-grooves 2011a, which are spaced apart along a second direction Y, and the thickened portion 202 is located between at least two adjacent sub-grooves 2011a, with the second groove 202a communicating with two adjacent sub-grooves 2011a. By positioning the thickened portion 202 between adjacent sub-grooves 2011a, the thickened portion 202 is positioned above the first groove 2011, so that the paste can pass through the thickened portion 202 and the first groove 2011, thereby obtaining a first connection portion 22 with a higher printing height.

[0117] Referring to Figure 12, the second groove 202a can penetrate both ends of the thickened portion 12 along the second direction Y (the direction of extension of the length of the second groove 202a). In other words, in the second direction Y, the second groove 202a and the first groove 2011 are in communication with each other. In this way, it is possible to avoid situations where the transmission of paste is obstructed during printing, resulting in uneven printing of the fingers, and it is advantageous to make the printed fingers flatter.

[0118] As can be seen from the above, a screen plate structure with a high aperture ratio is weakened in strength at the corresponding locations of the grooves, and this problem exists not only at the first groove 2011 for printing the first finger 21, but also at the second groove 202a for printing the first connecting portion 22.

[0119] To enhance the structural strength of the substrate 210 at the location corresponding to the second groove 202a, as shown in Figures 13 and 14, a reinforcing structure 203 is provided corresponding to the second groove 202a in the thickened portion 202. The reinforcing structure 203 can provide a stronger mechanical support effect for the substrate 210. The reinforcing structure 203 may have a hollow region which can communicate with the second groove 202a, thereby forming a deeper paste discharge area in the second groove 202a and the hollow region corresponding to the projection of the hollow region, and forming a first connection portion 22 with a higher printing height.

[0120] Selectively, the reinforcing structure 203 may employ, for example, an entangled wire structure, and the cross-sectional shape of the reinforcing structure 203 may be, for example, a mesh, honeycomb, or comb-like structure. For example, as shown in Figures 13 and 14, Figures 13 and 14 show that the reinforcing structure 203 is honeycomb-shaped.

[0121] In some embodiments, the reinforcing structure 203 is located on the upper layer of the thickened portion 202. Specifically, the thickened portion 202 may include a skeletal layer (not shown) and a printable layer (not shown), and in the direction of paste entry (i.e., the direction in which the paste enters the screen plate during printing), the skeletal layer is located in front of the printable layer. The skeletal layer is provided with a honeycomb-shaped reinforcing structure 203, and a second open groove 202a is formed in the printable layer.

[0122] Because the skeletal layer is located above the printing layer, after the paste enters the screen printing plate, it first passes through the skeletal layer before entering the printing layer. In other words, the paste ultimately reaches the semi-finished solar cell from the groove in the printing layer. By providing the reinforcing structure 203 in the skeletal layer, the influence of the reinforcing structure 203 on the paste's formation can be reduced, improving print quality. Furthermore, the reinforcing structure 203 located in the skeletal layer prevents the paste in the skeletal layer from being scraped off when the paste is squeegeeed by the squeegee blade, allowing as much paste as possible to remain in the skeletal layer, thus enabling the paste in the skeletal layer and the paste in the printing layer to accumulate and be printed on the surface of the semi-finished solar cell. Overall, the height of the paste printed by the reinforcing structure is approximately the same as the sum of the thicknesses of the skeletal layer and the printing layer. Furthermore, the fact that the height of the paste printed in the reinforcement structure is approximately the same as the sum of the thicknesses of the skeletal layer and the printed layer can be interpreted as either the height of the paste printed in the reinforcement structure being the same as the sum of the thicknesses of the skeletal layer and the printed layer, or the height of the paste printed in the reinforcement structure being slightly different from the sum of the thicknesses of the skeletal layer and the printed layer.

[0123] As another embodiment, referring to Figure 15, if the substrate 210 is not provided with a thickened portion 202 for forming a first connection portion 22 that is taller, it should be noted that the printed groove for forming the first connection portion 22 may be provided with a reinforcing structure 203 to increase the structural strength of the substrate 210.

[0124] In some embodiments, referring to Figure 16, the height H4 of the reinforced portion 202 is 1 μm to 3 μm. Selectively, the height H4 of the reinforced portion 202 may be 1 μm to 2 μm, 1 μm to 1.5 μm, or 1.5 μm to 2 μm, etc. For example, H4 may be 1 μm, 2 μm, or 3 μm, etc. Setting the height of the reinforced portion 202 to 1 μm to 3 μm corresponds to further thickening the first connecting portion 22 by 1 μm to 3 μm, taking into account that the first finger 21 of a certain height can be formed from the beginning, and a height of the first connecting portion 22 that satisfies the welding requirements can be obtained.

[0125] In some embodiments, the opening depth H5 of the first groove 2011 is 4 μm to 10 μm. Selectively, the opening depth H5 of the first groove 2011 may be 4 μm to 6 μm, 4 μm to 8 μm, 6 μm to 8 μm, 6 μm to 10 μm, or 8 μm to 10 μm, etc. For example, the opening depth H5 of the first groove 2011 may be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, etc.

[0126] By limiting the depth of the first groove 2011 to a reasonable range, the height of the formed first finger 21 can be reduced, thereby reducing paste consumption and the printing difficulty caused by the height of the printed electrode wire being too high. Furthermore, by controlling the height of the first finger 21 to a reasonable range, an optimal balance can be obtained between current transmission capability and reduction of paste consumption. If the height of the first finger 21 is too low, the contact resistance and line resistance of the first finger 21 increase, reducing the current transmission capability of the solar cell 100. If the height of the first finger 21 is too high, the paste consumption of the first finger 21 increases, which is detrimental to reducing the manufacturing cost of the solar cell 100. Therefore, by setting the opening depth H5 of the first groove 2011 to 4 μm to 10 μm, an optimal balance can be obtained between the current transmission capability and manufacturing cost of the solar cell 100.

[0127] In a third aspect, the present invention further discloses a photovoltaic module (not shown). The photovoltaic module includes the solar cell 100 described in the first aspect above, or the photovoltaic module includes a solar cell manufactured by the screen plate structure described in the second aspect above. It can be understood that a photovoltaic module having the solar cell 100 described above also has all the technical effects of the solar cell 100 described above. The above technical effects have already been described in detail in the examples of the solar cell 100 and will not be described again here.

[0128] Of course, the solar cell may further include a frame, photovoltaic glass, sealing material, etc., and together with these, it constitutes a photovoltaic module that can be applied to various outdoor environments, such as rooftops and building surfaces, and is widely used in photovoltaic systems.

[0129] The solar cells, screen plate structures, and photovoltaic power generation modules disclosed in the embodiments of the present invention have been described in detail above. In this paper, the principles and embodiments of the present invention are explained using specific examples, and the above description of embodiments is merely for the purpose of understanding the solar cells, screen plate structures, and photovoltaic power generation modules of the present invention and their core concepts. At the same time, those skilled in the art may modify any of the specific embodiments and application scopes based on the concept of the present invention, and for this reason, the contents of this specification should not be understood as limiting the present invention. [Explanation of symbols]

[0130] 100... Solar cells 10...Semi-finished solar cells 10a...Front 10b...Back 20...1st electrode 21. First finger 22...First connection section 221...Busbar connection cable 222... Finger connector wire 23...1st Bus Bar 30...2nd electrode 31...Second finger 32...Second connection section 33...Second bus bar X...first direction Y···Second direction H1...Maximum height of the first connection point H2...Maximum height of the first finger connected to the first connection point H3...Maximum height of the second connection point H4... Height of the thickened section H5...Opening depth of the first groove L1...The total length of the busbar connection wire in the second direction and / or the total length of the finger connection wire in the second direction W1... Minimum width of busbar connection wires and / or finger connection wires in the first direction W2...Maximum width of the busbar connection wire in the first direction W3...Maximum width of the finger connection wire in the first direction 200-screen version structure 210... Circuit board 201...Main body 2011...1st open groove 2011a... Sub-groove 202...Thickening section 202a...Second open groove 203...Reinforcement structure H4... Thickness of the thickened section H5...Opening depth of the first groove L1...Length of the second groove in the second direction W4...Minimum width of the second groove in the first direction W5...Maximum width of the second groove in the first direction

Claims

1. Including a semi-finished solar cell and a first electrode, The first electrode is provided on the semi-finished solar cell and includes a plurality of first fingers and a plurality of first connecting portions, the plurality of first fingers are provided at intervals along a first direction and each first finger extends along a second direction, the plurality of first connecting portions are provided at intervals along the first direction and the first connecting portions are connected to the first fingers and some of the first connecting portions are welded to a solder ribbon. The maximum height H1 of the first connection satisfies 4 μm ≤ H1 ≤ 10 μm, and the first direction and the second direction intersect. A solar cell characterized by the following features.

2. The smoothing factor of the first finger is smaller than the smoothing factor of the first connection. The solar cell according to feature 1.

3. The first electrode further includes a plurality of first busbars, the plurality of first busbars are spaced apart along the second direction, each first busbar extends along the first direction, and each first busbar is provided intersecting the first connection portion. The maximum height H1 of the first connection is greater than the maximum height of the first busbar corresponding to the first connection. The solar cell according to feature 1.

4. The maximum height of the first finger connected to the first connection part is H2, and H1 ≥ 1.2H2 to 3H2. The solar cell according to feature 1.

5. The maximum height of the first finger connected to the first connection part is H2, and the difference between H1 and H2 is in the range of 1 μm to 4 μm. The solar cell according to feature 1.

6. The maximum height H2 of the first finger connected to the first connection part satisfies 4 μm ≤ H2 ≤ 6 μm. The solar cell according to feature 1.

7. The solar cell further includes a second electrode, The second electrode is provided on the semi-finished solar cell and includes a plurality of second fingers and a plurality of second connection parts. The plurality of second fingers are provided at intervals along the first direction, each second finger extends along the second direction, and the plurality of second connecting portions are provided at intervals along the first direction, the second connecting portions are connected to the second fingers, and some of the second connecting portions are welded to a solder ribbon. The maximum height of the second connection is H3, and H1 > H3. The solar cell according to feature 1.

8. The maximum height H3 of the second connection satisfies 4 μm ≤ H3 ≤ 8 μm. The solar cell according to feature 7.

9. The polarity of the first electrode and the polarity of the second electrode are opposite. The first electrode is provided on the front of the semi-finished solar cell, and the second electrode is provided on the back of the semi-finished solar cell. Alternatively, both the first electrode and the second electrode are provided on the back surface of the semi-finished solar cell. The solar cell according to feature 7.

10. The first connection includes a finger connection wire and a busbar connection wire, and the finger connection wire overlaps with at least a portion of the busbar connection wire. The solar cell according to feature 1.

11. A silicon-containing dielectric layer is present in the corresponding region between the busbar connection line and the semi-finished solar cell. The solar cell according to feature 10.

12. The busbar connection wire covers the finger connection wire. The solar cell according to feature 10.

13. The total length L1 of the busbar connection wire and / or the finger connection wire in the second direction is 1 mm to 1.5 mm. and / or the minimum width W1 in the first direction of the busbar connection line and / or the finger connection line is 10 μm to 20 μm. and / or, the maximum width W2 of the busbar connection line in the first direction is 50 μm to 80 μm. And / or, the maximum width W3 of the finger connection wire in the first direction is 25 μm to 40 μm. The solar cell according to feature 10.

14. A screen plate structure applicable to solar cells, The aforementioned solar cells include semi-finished solar cells. The aforementioned screen plate structure includes a substrate, The substrate includes a main body and a thickened portion, the thickened portion being provided on the main body along the thickness direction of the main body, the main body having a plurality of first grooves that penetrate along its own thickness direction, the plurality of first grooves being provided at intervals along the first direction, and each of the first grooves extending along the second direction, The thickened portion has a second groove extending along the second direction, the second groove corresponds to at least one of the first grooves, and penetrates the main body along the thickness direction of the main body and communicates with the first groove. Where the first direction and the second direction intersect, A screen panel structure characterized by the following features.

15. Each of the first grooves includes a plurality of sub-grooves spaced apart along the second direction, the thickened portion is located between at least two adjacent sub-grooves, and the second groove connects two adjacent sub-grooves. The screen plate structure according to feature 14.

16. The thickness H4 of the thickened portion is 1 μm to 3 μm. The screen plate structure according to feature 14.

17. The opening depth H5 of the first groove is 4 μm to 10 μm. The screen plate structure according to feature 14.

18. A solar cell according to any one of claims 1 to 13, or a solar cell manufactured by a screen plate structure according to any one of claims 14 to 17, A solar power generation module characterized by the following features.

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