A solar cell and photovoltaic module without a main grid

Abstract

The application relates to the technical field of solar cells, in particular to a main-grid-free solar cell and a photovoltaic module. The main-grid-free solar cell comprises a cell body, a plurality of thin grids and connecting grid lines. The cell body has two oppositely arranged cell surfaces. The plurality of thin grids are arranged on at least one cell surface in a spaced manner, and the direction of the spaced arrangement is a first direction. The extension direction of the thin grids is a second direction, and the second direction intersects the first direction. At least two adjacent thin grids each have a plurality of overlapping segments. Each connecting grid line is connected between two adjacent thin grids. The two ends of at least one connecting grid line are respectively connected to the overlapping segments of the two thin grids, and the connecting grid line and the two overlapping segments connected thereto form an interconnecting overlapping structure. The main-grid-free solar cell is provided with the interconnecting overlapping structure, so that the overlapping effect of the thin grids and the conductive wires is better, the risk of thin grid breakage is reduced, and the light-shielding area is not excessively increased when the breakage is prevented.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a gridless solar cell and photovoltaic module. Background Technology

[0002] Since gridless solar cells do not have a main grid, the current collected by the fine grid needs to be channeled to the conductive filaments. When the fine grid is broken or the contact between the fine grid and the conductive filaments is poor, the current collected by the fine grid will have difficulty being conducted to the conductive filaments, resulting in increased current transmission losses and a decrease in the efficiency of the photovoltaic module. Utility Model Content

[0003] This application discloses a gridless solar cell and photovoltaic module, which can improve the connection effect between the fine grid and the conductive wire, reduce the risk of grid breakage, and achieve grid breakage prevention without increasing the shading area. The current collected by the fine grid can be efficiently concentrated to the conductive wire, which is beneficial to improving the efficiency of the photovoltaic module.

[0004] To achieve the above objectives, in a first aspect, embodiments of this application disclose a gridless solar cell, comprising:

[0005] A battery body having two battery surfaces disposed opposite to each other;

[0006] Multiple fine grids are spaced apart on at least one surface of the battery, with the spacing direction being a first direction. The extending direction of the fine grids is a second direction, which intersects the first direction. At least two adjacent fine grids each have a plurality of overlapping segments. The widest part of the overlapping segment has a width of W1 in the first direction, and the width of the remaining portion of the fine grid excluding the overlapping segments is W2; wherein W1 > W2; and

[0007] Each of the connecting grid lines is connected between two adjacent fine grids, and at least one of the connecting grid lines is connected at both ends to the overlapping sections of the two fine grids respectively, and the connecting grid line and the two connected overlapping sections form an interconnecting overlapping structure.

[0008] In one possible implementation of the first aspect, there are multiple connecting grid lines, which are spaced apart on the battery surface along the second direction;

[0009] In different regions of the battery surface, along the second direction, there are different spacings between two adjacent connecting grid lines.

[0010] In one possible implementation of the first aspect, the battery surface includes a central region and an edge region disposed at opposite ends of the central region along the first direction;

[0011] A portion of the fine grids are edge fine grids, and another portion of the fine grids are center fine grids; at least one edge region is provided with multiple edge fine grids, and the center region is provided with multiple center fine grids.

[0012] A portion of the connecting grid lines are edge connecting grid lines, and another portion of the connecting grid lines are middle connecting grid lines; wherein multiple edge connecting grid lines spaced apart in the second direction are connected between two adjacent edge grid lines, and the spacing between two adjacent edge connecting grid lines in the second direction is D1; ​​wherein multiple middle connecting grid lines spaced apart in the second direction are connected between two adjacent middle grid lines, and the spacing between two adjacent middle connecting grid lines in the second direction is D2;

[0013] Where D1 < D2.

[0014] In a possible implementation of the first aspect, the overlapping segment on the edge grating is an edge overlapping segment, and the overlapping segment on the middle grating is a middle overlapping segment;

[0015] At least one of the edge overlap segments has a length of L1 in the second direction;

[0016] At least one of the middle overlapping sections has a length of L2 in the second direction;

[0017] Where L1 > L2.

[0018] In a possible implementation of the first aspect, multiple central connecting gate lines arranged at equal intervals in the second direction form a row, and the multiple rows of central connecting gate lines are arranged along the first direction; in the first direction, the Nth central fine gate and the N+1th central fine gate are connected by the Nth row of central connecting gate lines, and the N+2th central fine gate and the N+3th central fine gate are connected by the N+1th row of central connecting gate lines; where N is a positive integer;

[0019] Alternatively, the central connecting grid lines spaced apart in the second direction are arranged in a row, and multiple rows of central connecting grid lines are arranged along the first direction; in the first direction, the Nth central fine grid and the N+1th central fine grid are connected by the Nth row of central connecting grid lines, and the N+1th central fine grid and the N+2th central fine grid are connected by the N+1th row of central connecting grid lines, and at least one of the Nth row of central connecting grid lines is staggered from at least one of the N+1th row of central connecting grid lines in the second direction; where N is a positive integer.

[0020] In a possible implementation of the first aspect, multiple edge connection grid lines spaced apart in the second direction form a row, and multiple rows of edge connection grid lines are arranged along the first direction;

[0021] In the first direction, the Mth edge fine gate and the (M+1)th edge fine gate are connected by the Mth row of edge connecting gate lines, and the (M+1)th edge fine gate and the (M+2)th edge fine gate are connected by the (M+1)th row of edge connecting gate lines, and at least one of the Mth row of edge connecting gate lines is offset from at least one of the (M+1)th row of edge connecting gate lines in the second direction; where M is a positive integer.

[0022] In a possible implementation of the first aspect, the number of edge grids on any of the edge regions is 4 to 12.

[0023] And / or, in the first direction, the spacing between two adjacent edge grids is 0.9 mm to 1.1 mm.

[0024] In a possible implementation of the first aspect, each of the multiple fine grids has a plurality of overlapping segments spaced apart along the second direction, and some of the overlapping segments are located at the connection between the fine grid and a plurality of the connecting grid lines, while the other portion of the overlapping segments are located at the offset points between the fine grid and the connecting grid lines, and the orthographic projections of the plurality of overlapping segments on these fine grids in the first direction coincide.

[0025] In one possible implementation of the first aspect, in the second direction, the width of at least one of the overlapping segments narrows from the middle to both ends.

[0026] In a possible implementation of the first aspect, the overlapping section includes an overlapping portion and two narrowing portions, each of the narrowing portions being connected to each end of the overlapping portion in the second direction, the width of each of the narrowing portions in the first direction narrowing away from the overlapping portion, the width of the widest point of the narrowing portion being equal to the width of the overlapping portion, and the width of the overlapping portion being equal to the width of the widest point of the overlapping section.

[0027] And / or, the width W1 of the widest part of the overlapping section in the first direction is 30μm to 60μm.

[0028] In one possible implementation of the first aspect, a plurality of interconnecting overlap structures are arranged in a column along the first direction, and the plurality of columns of the interconnecting overlap structures are spaced apart along the second direction on the battery surface.

[0029] In a possible implementation of the first aspect, the battery body includes a silicon substrate, a doped layer, and a functional film. The doped layer and the functional film are sequentially stacked on the surface of the silicon substrate in a direction away from the silicon substrate. One of the battery surfaces is the side of the functional film away from the doped layer. The fine grid and the connecting grid lines penetrate the functional film and make ohmic contact with the doped layer.

[0030] And / or, the connecting grid line is straight, the connecting grid line extends along the first direction, and the length of the connecting grid line is equal to the spacing D3 between two adjacent fine grids in the first direction;

[0031] And / or, the spacing D3 between two adjacent fine grids in the first direction is 0.9 mm to 1.1 mm;

[0032] And / or, the width W2 of the remaining portion of the fine grid, excluding the overlapping section, is 10 μm to 30 μm;

[0033] And / or, the first direction and the second direction are perpendicular.

[0034] Secondly, embodiments of this application disclose a photovoltaic module including a plurality of electrically connected solar cells, at least one of which is a gridless solar cell as described in the first aspect.

[0035] In a possible implementation of the second aspect, the photovoltaic module further includes:

[0036] A plurality of conductive filaments, the conductive filaments overlapping the interconnection structure to electrically connect the gridless solar cell; and

[0037] A light-transmitting film is provided, which covers the surface of the battery so that the conductive wire is disposed between the light-transmitting film and the gridless solar cell.

[0038] Compared with the prior art, the beneficial effects of this application include at least the following:

[0039] This gridless solar cell optimizes the current collection capability of the fine grid by setting up an interconnection structure composed of thickened overlapping sections and connecting grid lines, which combines overlapping and interconnection functions, thereby improving the efficiency of photovoltaic modules using this gridless solar cell.

[0040] Regarding the overlap function, this application replaces the overlap between two thin gates and the conductive wire with an interconnect overlap structure consisting of two overlap segments and a connecting gate line. This results in a larger contact area and a better overlap effect. In other words, the overlap effect between this interconnect overlap structure and the conductive wire is better. Furthermore, the width W1 of the widest overlap segment in the first direction is wider than the width W2 of the remaining portion of the thin gate excluding the overlap segment. The wider overlap segment indicates that more material in the overlap segment can alloy with the conductive wire and resist the silver etching reaction of the conductive wire, thereby reducing the probability of gate breakage.

[0041] Regarding the interconnection function, the connecting grid lines also enable electrical connection between two adjacent fine grids to prevent grid breakage. As mentioned above, a wider overlap section reduces the likelihood of grid breakage. The connecting grid lines connect the two fine grids through these two overlap sections, resulting in better grid breakage prevention and a lower risk of electrical connection disconnection. Since the conductive filaments are already positioned to block light, when the connecting grid lines overlap with the conductive filaments, the orthographic projection of the connecting grid lines on the cell surface is at least partially within the orthographic projection of the conductive filaments on the cell surface. This achieves grid breakage prevention through the connecting grid lines without increasing the shading area excessively, allowing more light to be absorbed by the cell body, which is beneficial for improving the conversion efficiency of this gridless solar cell.

[0042] In summary, this gridless solar cell, by setting an interconnection and overlapping structure, improves the overlap effect between the fine grid and the conductive filaments, reduces the risk of grid breakage, and achieves grid breakage prevention without increasing the shading area excessively. The current collected by the fine grid can be efficiently concentrated to the conductive filaments, which is beneficial to improving the efficiency of the photovoltaic module. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the structure of a gridless solar cell disclosed in an embodiment of this application;

[0045] Figure 2 for Figure 1 A schematic diagram of the connection between a gridless solar cell and conductive wires;

[0046] Figure 3 for Figure 2 A magnified view of a portion of region I shown in the diagram;

[0047] Figure 4 This is a schematic diagram of the structure of the overlapping segment disclosed in the embodiments of this application;

[0048] Figure 5 This is another structural schematic diagram of a gridless solar cell disclosed in an embodiment of this application;

[0049] Figure 6 for Figure 5 A magnified view of a portion of region II shown in the diagram;

[0050] Figure 7 for Figure 5 Another enlarged view of region II shown;

[0051] Figure 8 for Figure 5 Another enlarged view of region II shown in the diagram;

[0052] Figure 9 This is a schematic diagram illustrating another arrangement of the central connecting grid line disclosed in an embodiment of this application;

[0053] Figure 10 This is another structural schematic diagram of a gridless solar cell disclosed in an embodiment of this application;

[0054] Figure 11 for Figure 10 The AA cross-section shown in the figure;

[0055] Figure 12 for Figure 10 The BB cross-section shown in the figure;

[0056] Figure 13 This is a schematic diagram of the structure of a photovoltaic module disclosed in an embodiment of this application;

[0057] Figure 14 This is another structural schematic diagram of a photovoltaic module disclosed in an embodiment of this application.

[0058] Explanation of reference numerals in the attached figures:

[0059] 10. Gridless solar cell; 11. Cell body; 111. Cell surface; 1111. Central region; 1112. Edge region; 112. Silicon substrate; 113. Doped layer; 114. Functional film; 12. Fine grid; 12a. Edge fine grid; 12b. Central fine grid; 121. Overlap section; 121a. Edge overlap section; 121b. Central overlap section; 1211. Overlap portion; 1212. Narrowing portion; 122. Fine grid main body section; 123. Connecting grid line; 123a. Edge connecting grid line; 123b. Central connecting grid line; 124. Interconnection overlap structure; Y, First direction; X, Second direction; 20. Conductive filament; 30. Transparent film; 40. Front glass; 50. Front encapsulant film; 60. Solar cell string preform; 70. Back encapsulant film; 80. Back glass. Detailed Implementation

[0060] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0061] In this application, the terms "set up," "equipped with," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0062] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0063] Gridless solar cells reduce the overall shading area of ​​the grid electrodes by eliminating the need for a main grid, thereby improving the conversion efficiency of the solar cells and the overall power generation of the photovoltaic modules. Furthermore, since gridless solar cells do not require printed main grids, the consumption of printing paste is reduced to some extent, which helps lower manufacturing costs.

[0064] During the manufacturing stage of photovoltaic modules, the grid of a gridless solar cell needs to be alloyed with conductive filaments to achieve electrical connection between them. However, to achieve a lower shading area and less paste consumption, the grid is narrower. Narrower grids are prone to poor contact with the conductive filaments, and contain less electrode material (e.g., silver). During alloying, the grid is susceptible to silver corrosion caused by the conductive filaments, leading to grid breakage. When grid breakage occurs, the current in that localized area cannot be transmitted to the nearest conductive filament and must be transmitted to a more distant one. This results in a longer current transmission path, increased local resistance, current accumulation, and heat generation, causing localized overheating. In summary, grid breakage and poor contact between the grid and conductive filaments make it difficult for the current collected by the grid to be conducted to the conductive filaments, increasing current transmission losses and reducing the efficiency of the photovoltaic module.

[0065] Specifically, in this application, "paste" refers to the paste used for printing grid electrodes, such as silver paste, silver-aluminum paste, or silver-coated copper paste. The silver etching reaction refers to the reaction between the tin-based alloy on the surface of the conductive wire and the silver in the electrode material to be soldered, thereby reducing the silver content in the electrode material.

[0066] The inventors discovered that by adding connecting grid lines between the fine grids, the current transmission path of the fine grids can be shortened, thus preventing grid breakage. However, adding connecting grid lines increases the overall light-shielding area of ​​the grid electrodes. If the connecting grid line is located directly under the conductive wire, grid breakage can easily occur at the connection point between the connecting grid line and the fine grid, failing to achieve the grid breakage prevention effect.

[0067] Based on the above analysis, the gridless solar cell provided in this application embodiment achieves grid breakage prevention by setting an interconnection overlap structure. The connecting grid lines in the interconnection overlap structure enable two adjacent fine grids to be electrically connected to each other. The overlap sections in the interconnection overlap structure are less prone to grid breakage. The connecting grid lines connect the two fine grids to each other through these two overlap sections, resulting in better grid breakage prevention and a lower risk of electrical connection disconnection. Since the conductive filaments are already placed in a shaded position, when the connecting grid lines overlap with the conductive filaments, the orthographic projection of the connecting grid lines on the cell surface is at least partially within the orthographic projection of the conductive filaments on the cell surface. Therefore, while achieving grid breakage prevention through the connecting grid lines, it does not increase the excessive shaded area, allowing more light to be absorbed by the cell body, which is beneficial to improving the conversion efficiency of the gridless solar cell.

[0068] The technical solution of this utility model will be described below with reference to the embodiments and accompanying drawings.

[0069] Firstly, such as Figure 1 As shown in the figure, this application discloses a gridless solar cell 10, which includes a cell body 11, multiple fine grids 12 and connecting grid lines 123.

[0070] The battery body 11 has two battery surfaces 111 arranged opposite to each other. Multiple fine grids 12 are spaced apart on at least one battery surface 111, with the spacing direction being a first direction Y. The extension direction of the fine grids 12 is a second direction X, which intersects the first direction Y. Each of at least two adjacent fine grids 12 has several overlapping segments 121. The widest part of the overlapping segment 121 in the first direction Y has a width of W1, and the width of the remaining portion of the fine grid 12 excluding the overlapping segment 121 is W2. Wherein, W1 > W2. For ease of understanding, the remaining portion of the fine grid 12 excluding the overlapping segment 121 is referred to below as: the fine grid body segment 122.

[0071] Each connecting grid line 123 is connected between two adjacent fine grids 12. At least one connecting grid line 123 is connected at both ends to the overlapping section 121 of the two fine grids 12 respectively, and this connecting grid line 123 and the two connected overlapping sections 121 form an interconnecting overlapping structure 124.

[0072] The beneficial effects of the gridless solar cell of this application will be explained below.

[0073] Please combine Figures 1 to 3 The gridless solar cell 10 optimizes the current collection capability of the fine grid 12 by setting an interconnection overlap structure 124 composed of thickened overlap sections 121 and connecting grid lines 123, so as to combine overlap function and interconnection function, thereby improving the efficiency of photovoltaic modules using the gridless solar cell 10.

[0074] Regarding the overlap function, this application replaces the two thin gates 12 with the conductive wire 20 by using an interconnect overlap structure 124 consisting of two overlap segments 121 and a connecting gate line 123. This results in a larger contact area and a better overlap effect. In other words, the overlap effect between the interconnect overlap structure 124 and the conductive wire 20 is better. Furthermore, the width W1 of the widest part of the overlap segment 121 in the first direction Y is wider than the width W2 of the remaining part of the thin gate 12 excluding the overlap segment 121. The wider overlap segment 121 indicates that there is more material in the overlap segment 121 to alloy with the conductive wire 20 and to resist the silver etching reaction of the conductive wire 20, thereby reducing the probability of gate breakage.

[0075] Regarding the interconnection function, the connecting grid line 123 also enables two adjacent fine grids 12 to be electrically connected to each other to achieve grid breakage prevention. As mentioned above, a wider overlap section 121 is less prone to grid breakage. The connecting grid line 123 connects the two fine grids 12 to each other through these two overlap sections 121, resulting in better grid breakage prevention and a lower risk of electrical connection disconnection. Since the conductive wire 20 is placed in a position that already blocks light, when the connecting grid line 123 overlaps with the conductive wire 20, the orthographic projection of the connecting grid line 123 on the cell surface 111 is at least partially within the orthographic projection of the conductive wire 20 on the cell surface 111. Thus, while achieving grid breakage prevention through the connecting grid line 123, it does not increase the light-blocking area excessively, allowing more light to be absorbed by the cell body 11, which is beneficial to improving the conversion efficiency of the gridless solar cell 10.

[0076] In summary, the gridless solar cell 10, by setting the interconnection and overlapping structure 124, improves the overlapping effect between the fine grid 12 and the conductive filament 20, and reduces the risk of grid breakage of the fine grid 12. It achieves grid breakage prevention without increasing the shading area excessively. The current collected by the fine grid 12 can be efficiently gathered to the conductive filament 20, which is beneficial to improving the efficiency of the photovoltaic module.

[0077] Furthermore, referring to Figure 3Multiple interconnecting structures 124 are arranged in a column along the first direction Y, and multiple columns of interconnecting structures 124 are spaced apart along the second direction X on the cell surface 111. Thus, during the photovoltaic module manufacturing stage, each conductive wire 20 can be placed along the first direction Y, and each conductive wire 20 overlaps with each column of interconnecting structures 124. Multiple interconnecting structures 124 in the same column are alloyed with the same conductive wire 20, allowing multiple positions along the length of the conductive wire 20 to form good contact with multiple fine grids 12, thereby better collecting the current on the multiple fine grids 12. Furthermore, the bonding force between each conductive wire 20 and the gridless solar cell 10 is also stronger.

[0078] Optionally, the first direction Y and the second direction X are perpendicular. Of course, the angle between the first direction Y and the second direction X can also deviate slightly from 90°, for example, it can be 80°, 85°, 89°, 91° or 95°, and this application embodiment does not limit this.

[0079] The fine grid and the overlapping sections set on the fine grid are described in detail below.

[0080] Refer to the return Figure 1 Optionally, the width W1 of the widest point of the overlapping segment 121 in the first direction Y is 30μm to 60μm, including any value within this width range, such as 30μm, 45μm, or 60μm. When the width W1 of the widest point of the overlapping segment 121 in the first direction Y meets the above-mentioned width range, the overlapping segment 121 has more electrode material, which can play a better role in preventing grid breakage when alloyed with the conductive wire 20. In addition, the overlapping segment 121 can avoid problems such as severe light shading caused by excessive width. That is, the light shading area of ​​the overlapping segment 121 is also small, and the amount of paste consumed during printing is low, which is conducive to cost reduction and efficiency improvement of the gridless solar cell 10.

[0081] Optionally, the width W2 of the portion of the fine grid 12 excluding the overlapping section 121 is 10μm to 30μm, for example, 10μm, 20μm, or 30μm. When the width W2 of the fine grid main body section 122 meets the above-mentioned width range, it indicates that the linewidth of the fine grid main body section 122 is relatively narrow, which is beneficial to reducing the light-blocking area of ​​the fine grid main body section 122 and the amount of ink consumed during printing. Furthermore, the fine grid main body section 122 can avoid printing abnormalities and excessively high resistivity caused by excessively narrow linewidth, that is, the resistivity of the fine grid main body section 122 is low, and the printing morphology is better.

[0082] In some embodiments, refer to Figure 2 and Figure 3Each of the multiple fine grids 12 has multiple overlapping segments 121 spaced apart along the second direction X, and some of the overlapping segments 121 are located at the connection between the fine grid 12 and a number of connecting grid lines 123, while the other part of the overlapping segments 121 are located at the offset points between the fine grid 12 and the connecting grid lines 123. The orthographic projections of the multiple overlapping segments 121 on these fine grids 12 in the first direction Y coincide.

[0083] It is understood that this application not only provides overlapping segments 121 at the connection between the connecting grid line 123 and the fine grid 12, but also provides overlapping segments 121 at the offset points between the fine grid 12 and the connecting grid line 123. The orthographic projections of these overlapping segments 121 in the first direction Y coincide, that is, these overlapping segments 121 are arranged in a row in the first direction Y, and each row of overlapping segments 121 is used to overlap each conductive wire 20. The conductive wire 20 can overlap not only on the interconnecting overlapping structure 124, but also on the overlapping segments 121 located at the offset points between the fine grid 12 and the connecting grid line 123. With more overlapping positions, the conductive wires 20 can be more densely arranged on the gridless solar cell 10, thereby better collecting the current of the fine grid 12 and shortening the current transmission path of the fine grid 12.

[0084] It should be noted that not all fine grids 12 need to have overlapping sections. For example, in the first direction Y, one or more fine grids 12 closest to the edge of the battery surface 111 do not need to be alloyed with the conductive wire, so these fine grids 12 may not have overlapping sections.

[0085] Reference Figure 3 and Figure 4 Considering the high probability of the middle portion of the overlap segment 121 contacting the conductive wire 20, and the fact that the overall width of the overlap segment 121 would cause severe light shading, in this application, in the second direction X, the width of at least one overlap segment 121 narrows from the middle to both ends. The conductive wire 20 mostly contacts the middle portion of the overlap segment 121. Since the middle portion of the overlap segment 121 is the widest, it indicates that more paste was used for printing in the middle portion, and that the middle portion of the overlap segment 121 contains more electrode material, such as silver. This allows the middle portion of the overlap segment 121 to better block the silver etching reaction of the conductive wire 20, giving the overlap segment 121 better anti-breakage performance.

[0086] Furthermore, referring to Figure 4 The overlapping section 121 includes an overlapping portion 1211 and two narrowing portions 1212. Each narrowing portion 1212 is connected to each end of the overlapping portion 1211 in the second direction X. The width of each narrowing portion 1212 in the first direction Y narrows away from the overlapping portion 1211. The width of the narrowing portion 1212 at its widest point is equal to the width of the overlapping portion 1211. The width of the overlapping portion 1211 is equal to the width of the widest point of the overlapping section 121.

[0087] The overlapping section 121 can overlap the conductive wire using a relatively wide overlapping portion 1211. Since the probability of the two ends of the overlapping section 121 overlapping with the conductive wire is relatively low, narrowing portions 1212 are provided at both ends of the overlapping section 121. The narrowing portions 1212 reduce the overall light-shielding area of ​​the overlapping section 121 by narrowing its width, thereby reducing the amount of ink consumed during printing of the overlapping section 121. Since the width difference between the overlapping portion 1211 and the fine grid main body section 122 is large, the narrowing portions 1212 can allow the overlapping section 121 to transition from a wider width to a narrower width, thereby better connecting the fine grid main body section 122 and the overlapping portion 1211. Furthermore, the width of the narrowest part of the narrowing portion 1212 can be equal to the width of the fine grid main body section 122.

[0088] More specifically, the shape of the overlapping portion 1211 can be square, and the shape of the narrowing portion 1212 can be trapezoidal. That is, the narrowing portion 1212 can narrow gradually. In addition, the narrowing portion can also narrow in a stepped manner, that is, the shape of the narrowing portion can be stepped.

[0089] Of course, the overlapping section may not have a narrowing section. For example, the width of the overlapping section is the same everywhere. In this case, the shape of the overlapping section is square.

[0090] The connection between the grid lines and the fine grid is explained in detail below.

[0091] To shorten the length of the connecting gate line 123 and thus reduce the current transmission path, refer to Figure 5 and Figure 6 The connecting grid line 123 is straight and extends along the first direction Y. The length of the connecting grid line 123 is equal to the distance D3 between two adjacent fine grids 12 in the first direction Y. Optionally, the distance D3 between two adjacent fine grids 12 in the first direction Y is 0.9mm to 1.1mm, including any value within this distance range, such as 0.9mm, 1.0mm, or 1.1mm. When the distance between two adjacent fine grids 12 meets the above-mentioned distance range, the fine grids 12 have sufficient density to better collect the current on the surface of the battery body 11. Furthermore, the fine grids 12 can also avoid severe light shading caused by excessively narrow spacing. In other words, setting the fine grids 12 to the above-mentioned distance range is beneficial for the absorption of light by the battery body 11.

[0092] Understandably, the shorter length of the straight connecting grid line 123 shortens the current transmission path and reduces the light-shielding area of ​​the connecting grid line 123 and the amount of ink consumed during printing.

[0093] Of course, the connecting grid lines can also be curved or broken, or they can be block-shaped. The shape of the block-shaped connecting grid lines can be square, I-shaped, trapezoidal, etc., and this application embodiment does not limit this.

[0094] The inventors discovered that the breakage rate, current harvesting capacity, and current transport path of the fine grid 12 may differ in different regions of the battery surface 111. Based on this, in some embodiments, such as... Figure 5 and Figure 6 As shown, there are multiple connecting grid lines 123, which are spaced apart along the second direction X on the battery surface 111. In different areas of the battery surface 111, the spacing between two adjacent connecting grid lines 123 along the second direction X has different spacing.

[0095] It is understandable that the spacing between two adjacent connecting grid lines 123 in the second direction X can be set differently according to the characteristics of the fine grid 12 breakage rate, current collection capacity, and current transmission path in the region. For example, in the area on the battery surface 111 where the fine grid 12 breakage rate is high, the spacing D1 between two adjacent connecting grid lines 123 in the second direction X is smaller, that is, the connecting grid lines 123 in this area are denser. Since the connecting grid lines 123 play a role in preventing grid breakage, and the connecting grid lines 123 are equivalent to additional current transmission lines between the fine grids 12, when the connecting grid lines 123 are denser, the grid breakage prevention effect in this area is improved more, and the current transmission path is more dispersed. On the battery surface 111, in the area where the breakage rate of the fine grid 12 is low, the spacing D2 between two adjacent connecting grid lines 123 in the second direction X is larger, that is, the connecting grid lines 123 in this area are sparser. This can achieve the effect of preventing grid breakage and reduce the number of connecting grid lines 123 in this area, thereby reducing the overall light-shielding area of ​​the connecting grid lines 123 in this area.

[0096] In this application, as Figure 5 and Figure 7 As shown, the battery surface 111 includes a central region 1111 and an edge region 1112 disposed at opposite ends of the central region 1111 along a first direction Y. A portion of the fine grids are edge fine grids 12a, and another portion of the fine grids are central fine grids 12b. At least one edge region 1112 is provided with multiple edge fine grids 12a, and the central region 1111 is provided with multiple central fine grids 12b.

[0097] Considering that some edge grids 12a are difficult to alloy with conductive wires due to process limitations, these edge grids 12a cannot make contact with the conductive wires to conduct electricity. In other words, only some edge grids 12a are alloyed with the conductive wires, resulting in fewer contact points. The current transport path of the edge grids 12a is relatively long and concentrated, leading to increased local resistance. Current accumulation generates heat, and excessively high local temperatures can alter the performance of the cell material, resulting in the blackening of the edge region 1112. Blackening refers to the aging phenomenon that occurs in semiconductor materials in solar cells under long-term high-temperature conditions. Defects may appear in the crystal structure of the material, leading to a decrease in light absorption and charge transport capabilities, which may manifest as a blackening of the cell surface 111.

[0098] To reduce the blackening of the edge area 1112, see [reference needed]. Figure 7 In some embodiments, a portion of the connecting gate lines are edge connecting gate lines 123a, and another portion are center connecting gate lines 123b. Multiple edge connecting gate lines 123a are spaced apart in the second direction X between two adjacent edge connecting gate lines 123a, and the distance between two adjacent edge connecting gate lines 123a in the second direction X is D1. Multiple center connecting gate lines 123b are spaced apart in the second direction X between two adjacent center connecting gate lines 123b, and the distance between two adjacent center connecting gate lines 123b in the second direction X is D2. Wherein, D1 < D2. For example, D1 is 7mm to 8mm, and D2 is 16mm to 18mm. Of course, D1 and D2 can also be other values, and this application embodiment does not limit them.

[0099] In short, the spacing of the edge connecting gate lines 123a is narrower than that of the center connecting gate lines 123b. The narrower and denser spacing of the edge connecting gate lines 123a helps to shorten the current transmission path of the fine edge gates 12a, reduce the series resistance, and effectively collect the current in the edge region 1112 at the module end, reducing the gate breakage rate in the edge region 1112 and preventing blackening in the edge region 1112.

[0100] Compared to the edge fine grid 12a, the central fine grid 12b allows each wire to contact and be electrically connected to the conductive filament. In other words, the central fine grid 12b has more contact points with the conductive filament, resulting in a shorter and more dispersed current transmission path. Therefore, in the central region 1111, the spacing between two adjacent central connecting grid lines 123b is widened, and the central connecting grid lines 123b are more sparse. This satisfies the interconnection requirements of the central fine grid 12b while reducing the number of central connecting grid lines 123b, thereby reducing the overall shading area of ​​the central connecting grid lines 123b and the amount of paste consumed during printing. This is beneficial for cost reduction and efficiency improvement of the gridless solar cell 10.

[0101] In summary, by differentiating the spacing between the central connecting grid line 123b and the edge connecting grid line 123a, this application enables the gridless solar cell 10 to avoid blackening in the edge region 1112 and reduce the number of central connecting grid lines 123b, thereby reducing the overall shading area and paste consumption of the connecting grid lines 123, and thus achieving cost reduction and efficiency improvement of the gridless solar cell 10.

[0102] Reference Figure 7 The overlapping section on the edge fine grid 12a is called edge overlapping section 121a, and the overlapping section on the middle fine grid 12b is called middle overlapping section 121b. Because the edge region 1112 is the starting position for the connection between the conductive wire and the battery body 11, the conductive wire is more prone to displacement in the edge region 1112, and the displacement range is often larger than that in the middle region 1111. Based on this, in some embodiments, at least one edge overlapping section 121a has a length of L1 in the second direction X. At least one middle overlapping section 121b has a length of L2 in the second direction X. Wherein, L1 > L2. For example, L1 is 1.5mm to 2.5mm, and L2 is 0.6mm to 1.4mm. Of course, L1 and L2 can also be other values, and this application embodiment does not limit them.

[0103] In other words, the edge overlap section 121a is longer than the middle overlap section 121b. Since the conductive wire 20 has a larger offset range in the edge region 1112, this application, by setting an edge overlap section 121a that is longer than the middle overlap section 121b, ensures that the longer edge overlap section 121a can still overlap with the conductive wire even when the conductive wire deviates significantly in the edge region 1112, thus achieving the anti-breakage function. Conversely, the conductive wire has a smaller offset range in the middle region 1111, and the shorter middle overlap section 121b can maintain overlap with the conductive wire even when it deviates in the middle region 1111. Furthermore, shortening its length reduces the light-blocking area and the wet weight of the printing paste.

[0104] The specific steps for setting up the edge connection grid lines are as follows:

[0105] In the embodiments of this application, reference is made to Figure 8 Multiple edge connecting grid lines 123a are arranged at intervals in the second direction X as a row, and multiple rows of edge connecting grid lines 123a are arranged along the first direction Y.

[0106] In the first direction Y, the Mth edge fine gate 12a and the (M+1)th edge fine gate 12a are connected by the Mth row of edge connecting gate lines 123a, and the (M+1)th edge fine gate 12a and the (M+2)th edge fine gate 12a are connected by the (M+1)th row of edge connecting gate lines 123a. At least one of the M rows of edge connecting gate lines 123a is offset from at least one of the (M+1)th row of edge connecting gate lines 123a in the second direction X. Here, M is a positive integer.

[0107] This arrangement allows the edge fine gates 12a to be interconnected through the edge connecting gate lines 123a, making the current transmission path of the edge fine gates 12a more dispersed. Furthermore, the adjacent rows of edge connecting gate lines 123a are staggered in the second direction X, which further disperses the current transmission path of the edge fine gates 12a, thereby significantly shortening the current transmission path of the edge fine gates 12a, reducing the series resistance, and reducing the blackening phenomenon in the edge region 1112.

[0108] It should be noted that the spacing of the edge connecting gate lines 123a is not necessarily smaller than the spacing of the center connecting gate lines 123b. For example, in Figure 8 In the middle, in the Mth row, the spacing between two adjacent edge connecting grid lines 123a can be the same as or greater than the spacing D2 between the two middle connecting grid lines 123b.

[0109] Optionally, the number of edge grids 12a on any edge region 1112 is 4 to 12, for example, 4, 6, 8, 10, or 12. In the first direction Y, the spacing between two adjacent edge grids 12a is 0.9 mm to 1.1 mm, for example, 0.9 mm, 1.0 mm, or 1.1 mm. Compared to the central region 1111, the edge connecting grid lines 123a of the edge region 1112 are denser, and the edge overlap section 121a is longer. The light shading of the edge region 1112 is more severe, but the current transmission effect is more significantly improved. When the number of edge grids 12a meets the above-mentioned range, and the spacing of the edge grids 12a meets the above-mentioned spacing range, the edge region 1112 has sufficient width in the first direction Y to better conduct the current from the edge of the battery body 11, and the edge region 1112 is not too wide, thus having a smaller impact on the light shading of the battery body 11.

[0110] The specific method for setting the central connecting grid line is as follows:

[0111] In one example, such as Figure 8As shown, multiple center connecting grid lines 123b arranged equidistantly in the second direction X form a row, and these rows of center connecting grid lines 123b are arranged along the first direction Y. In the first direction Y, the Nth center fine grid 12b and the (N+1)th center fine grid 12b are connected by the Nth row of center connecting grid lines 123b, and the (N+2)th center fine grid 12b and the (N+3)th center fine grid 12b are connected by the (N+1)th row of center connecting grid lines 123b. Here, N is a positive integer.

[0112] In this example, each pair of adjacent fine central grids 12b is considered a pair, and a row of central connecting grid lines 123b is provided between a pair of fine central grids 12b to interconnect the pair of fine central grids 12b. This eliminates the need to provide central connecting grid lines 123b between two pairs of fine central grids 12b, thereby reducing the overall light-blocking area of ​​the central connecting grid lines 123b.

[0113] In another example, such as Figure 9 As shown, the intermediate connecting grid lines 123b spaced apart in the second direction X form a row, and multiple rows of intermediate connecting grid lines 123b are arranged along the first direction Y. In the first direction Y, the Nth intermediate fine grid 12b and the (N+1)th intermediate fine grid 12b are connected by the Nth row of intermediate connecting grid lines 123b, and the (N+1)th intermediate fine grid 12b and the (N+2)th intermediate fine grid 12b are connected by the (N+1)th row of intermediate connecting grid lines 123b. At least one of the N rows of intermediate connecting grid lines 123b is offset from at least one of the (N+1)th row of intermediate connecting grid lines 123b in the second direction X. Here, N is a positive integer.

[0114] In this example, any two adjacent central fine gates 12b are connected by a central connecting gate line 123b, that is, all the central fine gates 12b are interconnected together, the current transmission paths of each central fine gate 12b are more dispersed, the local resistance is reduced, and local overheating is avoided.

[0115] The battery itself will be described in detail below.

[0116] In some embodiments, see Figures 10 to 12 The battery body 11 includes a silicon substrate 112, a doped layer 113 and a functional film 114. The doped layer 113 and the functional film 114 are stacked sequentially on the surface of the silicon substrate 112 in a direction away from the silicon substrate 112. One of the battery surfaces 111 is the side of the functional film 114 away from the doped layer 113. The fine grid 12 and the connecting grid line 123 penetrate the functional film 114 and make ohmic contact with the doped layer 113.

[0117] It is understood that the two battery surfaces 111 are arranged opposite each other along the thickness direction Z of the battery body, that is, the two battery surfaces 111 refer to the light-receiving surface and the back-lighting surface of the battery body 11. More specifically, multiple fine grids 12 are spaced apart on the light-receiving surface of the battery body 11; or, multiple fine grids are spaced apart on the back-lighting surface of the battery body; or, multiple fine grids are spaced apart on both the light-receiving and back-lighting surfaces of the battery body.

[0118] More specifically, 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 a boron diffusion layer or a phosphorus diffusion layer. The doped layer 113 can also be an N-type doped polysilicon layer or a P-type doped polysilicon layer. The functional film 114 can be a passivation film and / or an antireflection film. The material of the functional film 114 can be silicon nitride, silicon oxynitride, silicon oxide, or aluminum oxide.

[0119] For example, the gridless solar cell 10 is a passivated contact solar cell. When the doped layer 113 and the functional film 114 are located on the light-receiving surface of the silicon substrate 112, the cell body 11 also includes a dielectric layer 115, a doped polycrystalline silicon layer 116 and a back passivation film 117. The dielectric layer 115, the doped polycrystalline silicon layer 116 and the back passivation film 117 are sequentially stacked on the back surface of the silicon substrate 112 in a direction away from the silicon substrate 112.

[0120] Of course, the doped layer and functional film can also be disposed on the back surface of the silicon substrate. In this case, the doped layer is a doped polycrystalline silicon layer, and there is also a dielectric layer between the doped polycrystalline silicon layer and the silicon substrate.

[0121] As other examples, the cell type of this gridless solar cell can also be a heterojunction solar cell, a back-contact solar cell, or a tandem cell.

[0122] Secondly, referring to Figure 13 This application discloses a photovoltaic module including a plurality of electrically connected solar cells, at least one of which is a gridless solar cell 10 as described in the first aspect.

[0123] In some embodiments, refer to Figure 13 The photovoltaic module also includes a plurality of conductive wires 20 and a light-transmitting film 30. The conductive wires 20 overlap the interconnection structure 124 to electrically connect the gridless solar cell 10. The light-transmitting film 30 covers the surface 111 of the cell so that the conductive wires 20 are disposed between the light-transmitting film 30 and the gridless solar cell 10.

[0124] The processing procedure for the photovoltaic modules in this application is as follows: (Combined with...) Figure 13 and Figure 14First, conductive wires 20 are placed on the gridless solar cell 10, and then a light-transmitting film 30 is applied to form a solar cell string preform 60. After the film is fixed, the various components of the photovoltaic module, such as the front glass 40, the front encapsulant film 50, the solar cell string preform 60, the back encapsulant film 70, and the back glass 80, are stacked and arranged, and finally put into a laminator for heated lamination to obtain the photovoltaic module. The heated lamination temperature is 150℃~180℃. During the heated lamination process, the conductive wires 20 and the interconnection structure 124 form alloyed contacts; this technique is referred to as the film coating technology below.

[0125] The coating technology enables good contact between the gridless solar cell 10 and the conductive wires 20, reducing contact resistance and power loss. Using coating technology for the gridless solar cell 10 reduces production steps and equipment, such as eliminating the need for welding. Furthermore, the conductive wires 20 no longer need to be welded to the gridless solar cell 10. Since welding temperatures are generally above 250°C, while the heating lamination temperature is only 150°C to 180°C, the conductive wires 20 can be alloyed with the interconnection structure 124 at a lower processing temperature than the welding temperature. This lower processing temperature reduces the probability of grid breakage in the fine grid 12 and the connecting grid lines 123.

[0126] Optionally, the conductive wire 20 can be a metal conductive wire, and the material of the conductive wire 20 can be any one of copper, silver, aluminum, aluminum alloy, or copper-clad aluminum. The material of the light-transmitting film 30 can be an EVA (ethylene-vinyl acetate copolymer) film or a POE (polyolefin elastomer) film.

[0127] Of course, the conductive wire of this application can also be connected to the interconnection structure by welding, thereby electrically connecting the gridless solar cell; that is, the conductive wire can also be a welding strip.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A gridless solar cell, characterized in that, include: A battery body having two battery surfaces disposed opposite to each other; Multiple fine grids are spaced apart on at least one surface of the battery, and the direction of the spacing is a first direction. The extension direction of the fine grids is a second direction, and the second direction intersects the first direction. At least two adjacent fine grids each have a plurality of overlapping segments, the widest part of the overlapping segment having a width of W1 in the first direction, and the width of the remaining portion of the fine grid excluding the overlapping segments having a width of W2; wherein, W1 > W2; and Each of the connecting grid lines is connected between two adjacent fine grids, and at least one of the connecting grid lines is connected at both ends to the overlapping sections of the two fine grids respectively, and the connecting grid line and the two connected overlapping sections form an interconnecting overlapping structure.

2. The gridless solar cell according to claim 1, characterized in that, The connecting grid lines are multiple, and the multiple connecting grid lines are spaced apart along the second direction on the battery surface; In different regions of the battery surface, along the second direction, there are different spacings between two adjacent connecting grid lines.

3. The gridless solar cell according to claim 2, characterized in that, The battery surface includes a central region and an edge region disposed at opposite ends of the central region along the first direction; A portion of the fine grids are edge fine grids, and another portion of the fine grids are center fine grids; at least one edge region is provided with multiple edge fine grids, and the center region is provided with multiple center fine grids. A portion of the connecting grid lines are edge connecting grid lines, and another portion of the connecting grid lines are middle connecting grid lines; wherein multiple edge connecting grid lines spaced apart in the second direction are connected between two adjacent edge grid lines, and the spacing between two adjacent edge connecting grid lines in the second direction is D1; ​​wherein multiple middle connecting grid lines spaced apart in the second direction are connected between two adjacent middle grid lines, and the spacing between two adjacent middle connecting grid lines in the second direction is D2; Where D1 < D2.

4. The gridless solar cell according to claim 3, characterized in that, The overlapping section on the edge fine grid is an edge overlapping section, and the overlapping section on the middle fine grid is a middle overlapping section; At least one of the edge overlap segments has a length of L1 in the second direction; At least one of the middle overlapping sections has a length of L2 in the second direction; Where L1 > L2.

5. The gridless solar cell according to claim 3, characterized in that, Multiple central connecting grid lines arranged at equal intervals in the second direction form a row, and multiple rows of central connecting grid lines are arranged along the first direction; in the first direction, the Nth central fine grid and the N+1th central fine grid are connected by the Nth row of central connecting grid lines, and the N+2th central fine grid and the N+3th central fine grid are connected by the N+1th row of central connecting grid lines; where N is a positive integer; Alternatively, the central connecting grid lines spaced apart in the second direction are arranged in a row, and multiple rows of central connecting grid lines are arranged along the first direction; in the first direction, the Nth central fine grid and the N+1th central fine grid are connected by the Nth row of central connecting grid lines, and the N+1th central fine grid and the N+2th central fine grid are connected by the N+1th row of central connecting grid lines, and at least one of the Nth row of central connecting grid lines is staggered from at least one of the N+1th row of central connecting grid lines in the second direction; where N is a positive integer.

6. The gridless solar cell according to claim 3, characterized in that, Multiple edge connection grid lines spaced apart in the second direction form a row, and multiple rows of edge connection grid lines are arranged along the first direction; In the first direction, the Mth edge fine gate and the (M+1)th edge fine gate are connected by the Mth row of edge connecting gate lines, and the (M+1)th edge fine gate and the (M+2)th edge fine gate are connected by the (M+1)th row of edge connecting gate lines, and at least one of the Mth row of edge connecting gate lines is offset from at least one of the (M+1)th row of edge connecting gate lines in the second direction; where M is a positive integer.

7. The gridless solar cell according to claim 3, characterized in that, The number of edge grids on any of the aforementioned edge regions is 4 to 12; And / or, in the first direction, the spacing between two adjacent edge grids is 0.9 mm to 1.1 mm.

8. The gridless solar cell according to claim 1, characterized in that, Each of the multiple fine grids has multiple overlapping segments spaced apart along the second direction, and some of the overlapping segments are located at the connection between the fine grid and a plurality of the connecting grid lines, while the other portion of the overlapping segments are located at the offset points between the fine grid and the connecting grid lines. The orthographic projections of the multiple overlapping segments on these fine grids in the first direction coincide.

9. The gridless solar cell according to any one of claims 1 to 8, characterized in that, In the second direction, the width of at least one of the overlapping segments narrows from the middle to both ends.

10. The gridless solar cell according to claim 9, characterized in that, The overlapping section includes an overlapping portion and two narrowing portions. Each narrowing portion is connected to each end of the overlapping portion in the second direction. The width of each narrowing portion in the first direction narrows away from the overlapping portion. The width of the narrowing portion at its widest point is equal to the width of the overlapping portion, and the width of the overlapping portion is equal to the width of the overlapping section at its widest point. And / or, the width W1 of the widest part of the overlapping section in the first direction is 30μm to 60μm.

11. The gridless solar cell according to any one of claims 1 to 8, characterized in that, Multiple interconnecting structures are arranged in a row along the first direction, and the multiple rows of interconnecting structures are spaced apart on the surface of the battery along the second direction.

12. The gridless solar cell according to any one of claims 1 to 8, characterized in that, The battery body includes a silicon substrate, a doped layer, and a functional film. The doped layer and the functional film are sequentially stacked on the surface of the silicon substrate in a direction away from the silicon substrate. One of the battery surfaces is the side of the functional film away from the doped layer. The fine grid and the connecting grid lines penetrate the functional film and make ohmic contact with the doped layer. And / or, the connecting grid line is straight, the connecting grid line extends along the first direction, and the length of the connecting grid line is equal to the spacing D3 between two adjacent fine grids in the first direction; And / or, the spacing D3 between two adjacent fine grids in the first direction is 0.9 mm to 1.1 mm; And / or, the width W2 of the remaining portion of the fine grid, excluding the overlapping section, is 10 μm to 30 μm; And / or, the first direction and the second direction are perpendicular.

13. A photovoltaic module, characterized in that, It includes multiple electrically connected solar cells, at least one of which is a gridless solar cell according to any one of claims 1 to 12.

14. The photovoltaic module according to claim 13, characterized in that, The photovoltaic module also includes: A plurality of conductive filaments, the conductive filaments overlapping the interconnection structure to electrically connect the gridless solar cell; and A light-transmitting film is provided, which covers the surface of the battery so that the conductive wire is disposed between the light-transmitting film and the gridless solar cell.

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