Back contact solar cell, printed screen assembly and photovoltaic assembly

Abstract

The application relates to the technical field of back contact solar cells, in particular to a back contact solar cell, a printing screen assembly and a photovoltaic module. The back contact solar cell comprises two-polarity current collection grid lines, two-polarity solder pads and connecting grid lines. The two-polarity current collection grid lines are arranged on the back surface. The current collection grid lines are at least one row; each row of the current collection grid lines comprises a plurality of current collection grid lines with the same polarity and arranged at intervals along a first direction; the plurality of rows of the current collection grid lines are arranged at intervals into a plurality of columns along a second direction; and the plurality of columns of the current collection grid lines are arranged at intervals along the first direction, so that the adjacent two columns of the current collection grid lines have a fracture area. On each fracture area, the current collection grid line with the same polarity as the polarity of the solder pad is a same-polarity current collection grid line, the current collection grid line with the opposite polarity to the polarity of the solder pad is a different-polarity current collection grid line, at least one row of the same-polarity current collection grid lines is connected with the solder pad, and at least one row of the different-polarity current collection grid lines is connected with the connecting grid line.

Description

Technical Field

[0001] This application relates to the field of back-contact solar cell technology, and more particularly to a back-contact solar cell, a printed screen module, and a photovoltaic module. Background Technology

[0002] Back-contact solar cells are prone to problems with thick grid lines, meaning the width of the grid lines increases. This can lead to a series of abnormalities, such as short circuits due to the different polarities of the grid lines and an unattractive electrode structure, which are detrimental to the performance and stability of back-contact solar cells. Utility Model Content

[0003] This application discloses a back-contact solar cell, a printed screen assembly, and a photovoltaic module, which can reduce the problem of thick lines in the collector grid.

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

[0005] A battery body, the battery body having a back side;

[0006] Two types of collector grid lines are disposed on the back side; each type of collector grid line has at least one row; each row of collector grid lines includes multiple collector grid lines of the same polarity, spaced apart along a first direction, the first direction being the length direction of the collector grid lines; multiple rows of collector grid lines are spaced apart in multiple columns along a second direction, the second direction intersecting the first direction; multiple columns of collector grid lines are spaced apart along the first direction, so that there are break regions between adjacent columns of collector grid lines, the number of such break regions being multiple;

[0007] Two types of solder pads, each with a different polarity, are respectively disposed on different fracture regions; and

[0008] A connecting gate line is provided on each of the said break regions, and at least one connecting gate line with the opposite polarity to the pad is provided;

[0009] In each of the fracture regions, the collector grid lines with the same polarity as the pads are called same-polarity collector grid lines, and the collector grid lines with the opposite polarity to the pads are called opposite-polarity collector grid lines. At least one row of same-polarity collector grid lines is connected to the pads, and at least one row of opposite-polarity collector grid lines is connected to the connecting grid lines.

[0010] In a possible implementation of the first aspect, at least one of the connecting gate lines in each of the break regions has the same polarity as the pad and is connected to the pad, and at least one row of collector gate lines of the same polarity is connected to the connecting gate lines.

[0011] In one possible implementation of the first aspect, at least one row of the opposite polarity collector grid lines has an isolation break in each of the said break regions.

[0012] In a possible implementation of the first aspect, in each of the said break regions, the number of the isolation breaks is A, the number of the connecting gate lines is B, and the number of pads is Z; the number of rows of the collector gate lines is C, satisfying the following relationship: B≤CZA; and / or,

[0013] The number of rows of the collector grid is greater than or equal to 180 rows and less than or equal to 600 rows; and / or,

[0014] The number of pads in the same fracture area is multiple, and the multiple pads are arranged in a pad group at intervals along the second direction, with the number of pad groups being 10 to 60.

[0015] In a possible implementation of the first aspect, the width of the widest part of the connecting gate line along the second direction is W1, and the width of the collector gate line along the second direction is W2, satisfying the following relationship: W1 > W2;

[0016] The second direction is perpendicular to the first direction.

[0017] In a possible implementation of the first aspect, along the first direction, the width of the middle portion of the connecting gate line is W3, and the width of the end portion of the connecting gate line is W1, satisfying the following relationship: W1 > W3.

[0018] In a possible implementation of the first aspect, the connecting gate wire includes:

[0019] A first connecting sub-gate line, the first connecting sub-gate line extending along the first direction, and the dimension of the first connecting sub-gate line along the second direction being W3; and

[0020] Two second connecting sub-gate lines are provided at each end of the first connecting sub-gate line along the first direction, and the second connecting sub-gate lines extend along the second direction; the dimension of the second connecting sub-gate line along the second direction is W1.

[0021] In a possible implementation of the first aspect, along the second direction, the spacing between two adjacent rows of collector grid lines of the same polarity is D1, satisfying the following relationship: 0.01×D1≤W3≤0.1×D1; and / or,

[0022] 0.05×D1≤W1≤0.4×D1; and / or,

[0023] 0.5×D1≤L≤1.8×D1; where L is the length of the connecting gate line along the first direction;

[0024] 0.2×L≤D2≤0.9×L; where D2 is the spacing between two adjacent collector grid lines in the same row.

[0025] In one possible implementation of the first aspect, the battery body includes:

[0026] A silicon substrate having a backlight surface;

[0027] A first doped layer and a second doped layer with opposite doping types, the first doped layer and the second doped layer being alternately spaced along the second direction on the backlight surface; and

[0028] A functional film is disposed at least on the side of the first doped layer opposite to the silicon substrate and on the side of the second doped layer opposite to the silicon substrate;

[0029] In this configuration, one type of collector gate line penetrates the functional film to form an ohmic contact with the first doped layer, and the other type of collector gate line penetrates the functional film to form an ohmic contact with the second doped layer; the pads and the connecting gate lines are both disposed on the side of the functional film away from the silicon substrate.

[0030] In a possible implementation of the first aspect, the gate smoothing factor of the collector gate is less than 1 and greater than 0.01.

[0031] Secondly, embodiments of this application disclose a printing screen assembly, the printing screen assembly comprising:

[0032] A first printing screen has multiple rows of collector grid printing slots. Each row of collector grid printing slots includes multiple collector grid printing slots spaced apart along a third direction, where the third direction is the length direction of the collector grid printing slots. The multiple rows of collector grid printing slots are spaced apart in multiple columns along a fourth direction, and the multiple columns of collector grid printing slots are spaced apart along the third direction, so that there are discontinuous regions between adjacent columns of collector grid printing slots. The number of discontinuous regions is multiple. The fourth direction intersects with the third direction.

[0033] The second printing screen is provided with pad printing grooves and connecting grid printing grooves spaced apart from the pad printing grooves.

[0034] Thirdly, embodiments of this application disclose a photovoltaic module, including a plurality of electrically connected back-contact solar cells;

[0035] At least one of the back-contact solar cells is the back-contact solar cell described in the first aspect;

[0036] Alternatively, at least one of the back-contact solar cells, including its current collector lines, pads, and connecting lines, is printed using the screen printing assembly described in the second aspect.

[0037] Compared with the prior art, the beneficial effects of this application are:

[0038] In the back-contact solar cell of this application, there is a break region between two adjacent rows of current collector grid lines, which causes each row of current collector grid lines to be broken at the corresponding position. Correspondingly, on the printing screen of the current collector grid lines, the printing grooves of each row of current collector grid lines are also broken at the corresponding position, avoiding uneven stress caused by misaligned break positions. In other words, the current collector grid line printing grooves experience more uniform stress and less deformation during printing, resulting in more accurate printed patterns and reducing the problem of thick lines.

[0039] Based on this, in order to connect the broken collector grid lines into a continuous state, at least one row of collector grid lines of the same polarity is connected by a pad in each break area, and at least one row of collector grid lines of different polarities is connected by a connecting grid line. This allows the collector grid lines of the two polarities to be connected into a continuous state, which is beneficial for the current transmission of the collector grid lines and for shortening the current transmission path, thereby improving the performance and stability of the back contact solar cell.

[0040] In summary, the back-contact solar cell of this application reduces the problem of thick lines and improves the printing quality of the current collector lines by disconnecting each row of current collector grid lines at corresponding positions, thereby reducing the contact short circuit problem of the current collector grid lines and making the back-contact solar cell more aesthetically pleasing. Furthermore, this back-contact solar cell connects the disconnected current collector grid lines into a continuous state by setting pads and connecting grid lines in the break area, which is beneficial for current transmission in the current collector grid lines and shortens the current transmission path, thus improving the performance and stability of the back-contact solar cell. Attached Figure Description

[0041] 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.

[0042] Figure 1 This is a schematic diagram of a back-contact solar cell.

[0043] Figure 2 for Figure 1 A schematic diagram of the structure of a collector grid printing screen;

[0044] Figure 3 This is a schematic diagram of the structure of a back-contact solar cell disclosed in an embodiment of this application;

[0045] Figure 4 This is a schematic diagram of the connection between the connecting gate line and the collector gate line disclosed in an embodiment of this application;

[0046] Figure 5 This is a cross-sectional view of a back-contact solar cell disclosed in an embodiment of this application;

[0047] Figure 6 This is a schematic diagram of the structure of a printing screen assembly disclosed in an embodiment of this application.

[0048] Explanation of reference numerals in the attached figures:

[0049] 1. Back contact solar cell; 11. Cell body; 111. Silicon substrate; 112. First doped layer; 113. Second doped layer; 114. Functional film; 12. Current collector grid line; 12a. Same polarity current collector grid line; 12b. Different polarity current collector grid line; 121. Isolation break; 122. Thick line segment; 13. Pad; M13. Pad group; 14. Connecting grid line; 141. First connecting sub-grid line; 142. Second connecting sub-grid line; 15. Busbar grid line; X1. First direction; Y1. Second direction; A1. Break region;

[0050] 2. Printing screen assembly; 21. First printing screen; 211. Collector grid line printing groove; X2. Third direction; Y2. Fourth direction; A2. Discontinuity area; G. Discontinuity opening; 22. Second printing screen; 221. Pad printing groove; 222. Connecting grid line printing groove. Detailed Implementation

[0051] 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.

[0052] In this application, the terms "upper," "lateral," "longitudinal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0053] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0054] Furthermore, the terms "set up," "equipped with," and "connected" 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 these terms in this application based on the specific circumstances.

[0055] 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.

[0056] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a back-contact solar cell. Unlike other types of solar cells, the back-contact solar cell 1 has two types of current collector grids 12, both of which are located on its back side. Figure 1 In the example of a collector grid line 12 with one polarity, some collector grid lines 12 form isolation breaks 121 to isolate them from pads 13 with opposite polarity, while other collector grid lines 12 do not need to be isolated because they are offset from pads 13.

[0057] Reference Figure 2 , Figure 2 for Figure 1 A schematic diagram of the structure of a collector grid printing screen, in Figure 2 On the printing screen, some collector grid line printing grooves 211 have an interruption G on one side and no interruption G on the other side. The interruption G on one side will cause the collector grid line printing groove 211 to be subjected to different tensions during printing, that is, F1≠F2. The collector grid line printing groove 211 is subjected to uneven force, which in turn causes the problem of thick lines.

[0058] The thick line problem refers to the abnormal increase in the width of the collector grid line 12, forming a thick line segment 122. Since the spacing between the two collector grid lines 12 of different polarities is limited, the thick line segment 122 is prone to causing a series of abnormalities such as short circuits and unsightly electrode structure of the two collector grid lines 12 of different polarities, which is detrimental to the performance and stability of the back contact solar cell 1.

[0059] Based on the above analysis, the back-contact solar cell of this application reduces the problem of thick lines and improves the printing quality of the current collector grid lines by disconnecting each row of current collector grid lines at corresponding positions, thereby reducing the contact short circuit problem of the current collector grid lines and making the back-contact solar cell more aesthetically pleasing. Furthermore, this back-contact solar cell connects the disconnected current collector grid lines into a continuous state by setting pads and connecting grid lines in the break area, which is beneficial for current transmission in the current collector grid lines and shortens the current transmission path, thus improving the performance and stability of the back-contact solar cell.

[0060] The technical solution of this utility model will be described below with reference to the embodiments and accompanying drawings.

[0061] Please refer to Figure 3 This application discloses a back-contact solar cell 1, including a cell body 11, current collector grid lines 12 of two polarities, solder pads of two polarities 13, and connecting grid lines 14.

[0062] The battery body 11 has a back side. Both types of collector grid lines 12 are disposed on the back side. Each type of collector grid line 12 has at least one row. Each row of collector grid lines 12 includes multiple collector grid lines 12 of the same polarity, spaced apart along a first direction X1, where X1 is the length direction of the collector grid lines 12. Multiple rows of collector grid lines 12 are spaced apart in multiple columns along a second direction Y1, where Y1 intersects the first direction X1. Multiple columns of collector grid lines 12 are spaced apart along the first direction X1, such that there are multiple break regions A1 between adjacent columns of collector grid lines 12.

[0063] Two types of pads 13 are respectively disposed on different fracture regions A1. Each fracture region A1 is provided with at least one connecting gate line 14 with the opposite polarity to the pad 13.

[0064] In each fracture region A1, the collector grid lines with the same polarity as the pad 13 are called same polarity collector grid lines 12a, and the collector grid lines with the opposite polarity to the pad 13 are called opposite polarity collector grid lines 12b. At least one row of same polarity collector grid lines 12a is connected to the pad 13, and at least one row of opposite polarity collector grid lines 12b is connected to the connecting grid lines 14.

[0065] For ease of understanding, one polarity of the collector gate line 12, pad 13, and connecting gate line 14 is in Figure 3 Diagonal fill lines were used, and the collector gate line 12, pad 13, and connection gate line 14 of another polarity were... Figure 3 There is no filler in the middle to distinguish the polarity of collector gate line 12, pad 13 and connection gate line 14.

[0066] More specifically, the two polarity pads 13 include a positive polarity pad 13 and a negative polarity pad 13. Correspondingly, the two polarity pads 13 are respectively disposed on different fracture regions A1, meaning that the positive polarity pad 13 is disposed in one fracture region A1, and the negative polarity pad 13 is disposed in the other fracture region A1. Generally, in two adjacent fracture regions A1, the pads 13 in one fracture region A1 are all positive polarity, and the pads 13 in the other fracture region A1 are all negative polarity.

[0067] Specifically, the two polarities of the collector grid lines 12 include positive and negative polarity collector grid lines 12. When the pad 13 on the break region A1 is positive, the same polarity collector grid line 12a refers to the positive polarity collector grid line, the opposite polarity collector grid line 12b refers to the negative polarity collector grid line, the connection grid line 14 with the opposite polarity to the pad 13 is the negative polarity connection grid line 14, and the connection grid line 14 with the same polarity as the pad 13 is the positive polarity connection grid line.

[0068] Conversely, when the pad 13 on the fracture area A1 is negative, the same polarity collector gate line 12a is a negative polarity collector gate line, the opposite polarity collector gate line 12b is a positive polarity collector gate line, the connection gate line 14 with the opposite polarity to the pad 13 is a positive polarity connection gate line 14, and the connection gate line 14 with the same polarity as the pad 13 is a negative polarity connection gate line 14.

[0069] In this embodiment, the collector grid lines 12 are arranged in multiple rows and columns. It should be noted that the collector grid lines 12 in the same row are not necessarily aligned in a straight line, nor are the collector grid lines 12 in the same column. A break region A1 exists between adjacent columns of collector grid lines 12, causing each row of collector grid lines 12 to break at a corresponding position. Correspondingly, on the printing screen of the collector grid lines 12, the printing grooves of each row of collector grid lines 12 also break at corresponding positions, avoiding uneven stress caused by misaligned break points. In other words, the printing grooves of the collector grid lines 12 experience more uniform stress and deformation during printing, resulting in more accurate printed patterns and reducing the problem of thick lines.

[0070] Based on this, in order to connect the disconnected collector grid lines 12 into a continuous state, at least one row of collector grid lines 12a of the same polarity is connected by a pad 13 on each break area A1. Specifically, two collector grid lines 12a of the same polarity in the same row are connected by a pad 13, and at least one row of collector grid lines 12b of opposite polarity is connected by a connecting grid line 14. Specifically, two collector grid lines 12b of opposite polarity in the same row are connected by a connecting grid line 14. This allows the collector grid lines 12 of the two polarities to be connected into a continuous state, which is beneficial for the current transmission of the collector grid lines 12 and for shortening the current transmission path, thereby improving the performance and stability of the back contact solar cell 1.

[0071] In summary, the back-contact solar cell 1 of this application reduces the problem of thick lines and improves the printing quality of the current collector grid lines 12 by disconnecting each row of current collector grid lines 12 at corresponding positions, thereby reducing the contact short circuit problem of the current collector grid lines 12 and making the back-contact solar cell 1 more aesthetically pleasing. Furthermore, the back-contact solar cell 1 also connects the disconnected current collector grid lines 12 into a continuous state by setting pads 13 and connecting grid lines 14 in the break area A1, which is beneficial for current transmission of the current collector grid lines 12 and shortens the current transmission path, thereby improving the performance and stability of the back-contact solar cell 1.

[0072] The connection grid line 14 and the collector grid line 12 of this application will be described in detail below.

[0073] In some embodiments, please refer to Figure 3 On each break area A1, at least one connecting gate line 14 has the same polarity as the pad 13 and is connected to the pad 13. The connecting gate lines 14 are connected between at least one row of collector gate lines 12a of the same polarity.

[0074] In this way, on each fracture region A1, the same polarity collector grid lines 12a can be connected not only using pads 13 but also using connecting grid lines 14. Since pads 13 need to be soldered to the solder ribbon, their area is relatively large, resulting in a higher wet weight of the printing paste. Connecting grid lines 14, on the other hand, have lower area requirements and can be smaller than pads 13, resulting in a lower wet weight of the printing paste. In other words, some of the same polarity collector grid lines 12a can be connected continuously using connecting grid lines 14, which have a lower wet weight of printing paste, thereby reducing the total wet weight of the electrode structure (pads 13 and connecting grid lines 14) on each fracture region A1. Furthermore, this portion of the same polarity collector grid lines 12a can collect current to the pads 13 through connecting grid lines 14 and bus grid lines 15.

[0075] Considering that when the orthographic projection of pad 13 or bus line 15 in the first direction X1 coincides with the orthographic projection of the opposite polarity collector line 12b in the first direction X1, this portion of the opposite polarity collector line 12b can no longer be connected into a continuous state through the connecting gate line 14, please refer to... Figure 3 In some embodiments, at least one row of opposite polarity collector grid lines 12b has an isolation break 121 on each break region A1, and a pad 13 is located in the isolation break 121 and spaced apart from the opposite polarity collector grid lines 12b, so that the pad 13 and the opposite polarity collector grid lines 12b are insulated and isolated.

[0076] Furthermore, in each fracture region A1, the number of isolation fractures 121 is A, the number of connecting grid lines 14 is B, the number of pads 13 is Z, and the number of rows of collector grid lines 12 is C, satisfying the following relationship: B≤CZA. When the number Y of connecting grid lines 14 satisfies the above relationship, the fracture region A1 has enough connecting grid lines 14 to connect the broken collector grid lines 12 into a continuous state, and can also avoid excessive slurry consumption due to an excessive number of connecting grid lines 14.

[0077] Optionally, the number of rows of collector grid lines is greater than or equal to 180 rows and less than or equal to 600 rows. When the number of rows X of collector grid lines 12 meets the above numerical range, the spacing between the two rows of collector grid lines 12 is narrow enough to shorten the path of carrier transmission to the collector grid lines 12 and reduce carrier transmission loss. Furthermore, the spacing between the two rows of collector grid lines 12 is not too narrow, which is beneficial for improving the bifaciality of the back-contact solar cell 1.

[0078] Optionally, there are multiple pads 13 within the same fracture region A1, and these multiple pads 13 are arranged along the second direction Y1 to form pad groups M13, with the number of pad groups M13 ranging from 10 to 60. In this case, there are enough pad groups M13 and enough disconnection points for each row of collector grid lines 12, resulting in shorter lengths for each collector grid line 12, which helps reduce transmission losses. Furthermore, there are not too many pad groups M13. Since the warpage of the back contact solar cell 1 is directly proportional to the number of pad groups M13, having fewer than or equal to 60 pad groups M13 helps control the warpage of the back contact solar cell 1.

[0079] In some embodiments, please refer to Figure 4 The width of the widest part of the connecting gate line 14 along the second direction Y1 is W1, and the width of the collector gate line 12 along the second direction Y1 is W2, satisfying the following relationship: W1 > W2.

[0080] In short, the widest part of the connecting gate line 14 is wider than the collector gate line 12, and this design of the connecting gate line 14 provides a margin for the printing offset of the collector gate line 12. In this way, when the collector gate line 12 undergoes a certain degree of printing offset in the second direction Y1, the collector gate line 12 still overlaps the connecting gate line 14.

[0081] Considering that if the connecting grid line 14 is wider than the current collector grid line 12, the wet weight of the paste during printing the connecting grid line 14 will be higher, which may affect the bifaciality of the back contact solar cell 1. Therefore, please refer to... Figure 4 In this embodiment of the application, along the first direction X1, the width of the middle part of the connecting gate line 14 is W3, and the width of the end of the connecting gate line 14 is W1, satisfying the following relationship: W1 > W3.

[0082] In other words, the middle part of the connecting grid line 14 is narrower than the ends. In this way, the connecting grid line 14 can overlap the current collector grid line 12 through the wider ends, and provide a margin for the printing offset of the current collector grid line 12. The narrower middle part of the connecting grid line 14 can also reduce the wet weight of the paste during printing, and is also beneficial to improving the bifaciality of the back contact solar cell 1.

[0083] For example, the connecting grid line 14, which is narrow in the middle and wide at the ends, is H-shaped, also known as I-shaped.

[0084] Further, please refer to Figure 4 The connecting gate line 14 includes a first connecting sub-gate line and two second connecting sub-gate lines.

[0085] The first connecting sub-gate line extends along a first direction X1, and its dimension along a second direction Y1 is W3. Each second connecting sub-gate line is disposed at one end of the first connecting sub-gate line along the first direction X1, and extends along the second direction Y1. The dimension of each second connecting sub-gate line along the second direction Y1 is W1.

[0086] In other words, the connecting grid line 14 has wider second connecting sub-grid lines at both ends. These two wider second connecting sub-grid lines overlap the collector grid line 12 and provide a margin for printing offset of the collector grid line 12. The first connecting sub-grid line in the middle is narrower, which helps to reduce the wet weight of the paste during printing of the connecting grid line 14.

[0087] Optionally, please refer to the following: Figure 3 and Figure 4 Along the second direction Y1, the spacing D1 between two adjacent rows of collector grid lines 12 of the same polarity satisfies the following relationship: 0.01×D1≤W3≤0.1×D1. When W3 satisfies the above relationship, the width of the middle part of the connecting grid line 14 is narrow enough to effectively reduce the wet weight of the slurry in the connecting grid line 14. Furthermore, the middle part of the connecting grid line 14 is not too narrow to avoid excessive resistance and resulting in significant current transmission loss.

[0088] Optionally, 0.05×D1≤W1≤0.4×D1. When W1 satisfies the above relationship, the end of the connecting grid line 14 is wide enough, thus providing sufficient margin for the printing offset of the collector grid line 12 and improving the success rate of the overlap between the collector grid line 12 and the connecting grid line 14. Furthermore, the end of the connecting grid line 14 should not be too wide, so as not to cause the area of ​​the connecting grid line 14 to be too large and increase the wet weight of the paste during printing.

[0089] Optionally, 0.5×D1≤L≤1.8×D1; where L is the length of the connecting gate line 14 along the first direction X1. When L satisfies the above relationship, the connecting gate line 14 is short enough, thus leaving more space for the collector gate line 12 to collect current. Furthermore, the connecting gate line 14 is not too short, thereby reducing the difficulty of connecting the collector gate line 12 and the connecting gate line 14.

[0090] Optionally, in each row of collector grid lines 12, the spacing between two adjacent collector grid lines 12 is D2, satisfying the following relationship: 0.2×L≤D2≤0.9×L. In this way, the spacing between two adjacent collector grid lines 12 in each row is narrow enough, providing sufficient engineering margin for the overlap connection of the collector grid lines 12 to the grid lines 14 during printing, and the spacing between two adjacent collector grid lines 12 is not too narrow, thus avoiding excessive ink consumption during printing.

[0091] Optionally, multiple pads 13 are arranged in a group along the second direction Y1, and collector grid lines 12 are arranged in a row along the first direction X1. The number of groups of pads 13 is ≤60, and the number of rows of collector grid lines 12 is ≤400.

[0092] Where X is the product of the number of pad groups 13 and the number of rows of collector gate lines 12, and Y is the number of connecting gate lines 14, satisfying the following relationship: X > Y / 2, thus,

[0093] Optionally, the gate smoothing factor of collector gate line 12 is less than 1 and greater than 0.01. Gate smoothing factor S 2 The calculation method is as follows: Where X1, X2, ..., Xn are n height point values ​​derived from the height curve of collector grid line 12. It is the average value of these n height points. In one method for testing the grid line smoothing factor, a 3D microscope is used to measure the height profile of a longitudinal section of the collector grid line 12 of a certain length (e.g., 200 μm) along the length direction Y of the grid line at any magnification (e.g., 50x). Based on the height profile, a height curve is obtained, and multiple height coordinate values ​​X1, X2, ..., Xn are derived from the height curve. For example, some embodiments of this application derive 100 height point values, and the variance of these 100 height point values ​​is calculated using the concept of mathematical statistics. This variance is used to characterize the fluctuation of the height of the collector grid line 12, which is the grid line smoothing factor described in this application. It can be understood that the smaller the grid line smoothing factor, the more concentrated the multiple height point values ​​are around the average value, and the less the height fluctuation of the collector grid line 12 is.

[0094] Based on this, when the grid line smoothing factor is less than 1 and greater than 0.01, the height fluctuations of the collector grid line 12 are relatively small, indicating that the height of the collector grid line 12 is relatively uniform and the cross-sectional area of ​​the collector grid line 12 varies little. Since the line resistance of the collector grid line 12 is related to its cross-sectional area, when the cross-sectional area of ​​the collector grid line 12 varies little, the line resistance of the collector grid line 12 is also approximately the same, which is beneficial to improving the current transmission performance of the collector grid line 12, thereby improving the conversion efficiency of the back contact solar cell 1.

[0095] The battery body of this application will be described in detail below.

[0096] In some embodiments, refer to Figure 5 The battery body 11 includes a silicon substrate 111, a first doped layer 112 and a second doped layer 113 with opposite doping types, and a functional film 114.

[0097] The silicon substrate 111 has a backlight surface. A first doped layer 112 and a second doped layer 113 are alternately disposed on the backlight surface along a second direction Y1. A functional film 114 is disposed at least on the side of the first doped layer 112 facing away from the silicon substrate 111 and on the side of the second doped layer 113 facing away from the silicon substrate 111.

[0098] In this design, one type of collector gate line 12 penetrates the functional film 114 to form an ohmic contact with the first doped layer 112, while the other type of collector gate line 12 penetrates the functional film 114 to form an ohmic contact with the second doped layer 113. The pads 13 and the connecting gate lines 14 are both disposed on the side of the functional film 114 facing away from the silicon substrate 111.

[0099] Understandably, neither the connecting grid line 14 nor the pad 13 penetrates the functional film 114, and both can be printed using a non-burn-through paste. The printing grooves of the connecting grid line 14 and the pad 13 can be designed and printed on the same printing screen to simplify the printing process.

[0100] More specifically, the functional film 114 is, for example, an antireflective film and / or a passivation film, and the material of the functional film 114 is, for example, silicon oxide, silicon oxynitride, aluminum oxide, etc. The first doped layer 112 and the second doped layer 113 are, for example, semiconductor diffusion layers (boron diffusion layers, phosphorus diffusion layers) or doped polycrystalline silicon layers.

[0101] Reference Figure 6 This application discloses a printing screen assembly 2, which includes a first printing screen 21 and a second printing screen 22.

[0102] The first printing screen 21 has multiple rows of collector grid printing slots 211. Each row of collector grid printing slots 211 includes multiple collector grid printing slots 211 spaced apart along a third direction X2, where X2 is the length direction of the collector grid printing slots 211. The multiple rows of collector grid printing slots 211 are spaced apart in multiple columns along a fourth direction Y2, and the multiple columns of collector grid printing slots 211 are spaced apart along a third direction X2, so that there is a discontinuity region A2 between adjacent columns of collector grid printing slots 211. There are multiple discontinuity regions A2, and the fourth direction Y2 intersects with the third direction X2.

[0103] The second printing screen 22 is provided with a pad printing groove 221 and a connecting grid line printing groove 222 that is spaced apart from the pad printing groove 221.

[0104] The beneficial effects of the printing screen component 2 of this application will be explained below.

[0105] The current collector grid lines 211 of the first printing screen 21 are arranged in multiple rows and columns, with a discontinuity region A2 between adjacent columns of current collector grid lines 211. That is, each row of current collector grid lines 211 is interrupted at the corresponding position. This balances the forces on each current collector grid line 211 during printing along the fourth direction Y2, which helps to reduce the problem of thick lines in the current collector grids, improves the printing quality of the current collector grids, and further reduces the problem of short circuits in the current collector grids, making the appearance of the back contact solar cell more aesthetically pleasing.

[0106] Based on this, the second printing screen 22 prints pads through the pad printing groove 221 and prints connecting grid lines through the connecting grid line printing groove 222. The pads and connecting grid lines connect the disconnected collector grid lines into a continuous state, which is beneficial for the current transmission of the collector grid lines and shortens the current transmission path, thereby improving the performance and stability of the back contact solar cell.

[0107] It should be noted that there is no specific printing order for the first printing screen 21 and the second printing screen 22. For example, the second printing screen 22 can be used to print the pads and connecting grid lines on the battery body first, and then the first printing screen 21 can be used to print the current collector grid lines on the battery body. In addition, there are generally two first printing screens 21 to print current collector grid lines of two polarities.

[0108] This application discloses a photovoltaic module, including a plurality of electrically connected back-contact solar cells.

[0109] At least one back-contact solar cell is the back-contact solar cell disclosed in the embodiments of this application;

[0110] Alternatively, at least one back-contact solar cell's current collector grid, pads, and connecting grid are printed using the screen printing assembly disclosed in the embodiments of this application.

[0111] 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 back-contact solar cell, characterized in that, include: A battery body, the battery body having a back side; Two types of collector grid lines are disposed on the back side; each type of collector grid line has at least one row; each row of collector grid lines includes multiple collector grid lines of the same polarity, spaced apart along a first direction, the first direction being the length direction of the collector grid lines; multiple rows of collector grid lines are spaced apart in multiple columns along a second direction, the second direction intersecting the first direction; multiple columns of collector grid lines are spaced apart along the first direction, so that there are break regions between adjacent columns of collector grid lines, the number of such break regions being multiple; Two types of solder pads are respectively set on different fracture areas; as well as A connecting gate line is provided on each of the said break regions, and at least one connecting gate line with the opposite polarity to the pad is provided; In each of the fracture regions, the collector grid lines with the same polarity as the pads are called same-polarity collector grid lines, and the collector grid lines with the opposite polarity to the pads are called opposite-polarity collector grid lines. At least one row of same-polarity collector grid lines is connected to the pads, and at least one row of opposite-polarity collector grid lines is connected to the connecting grid lines.

2. The back-contact solar cell according to claim 1, characterized in that, In each of the said break regions, at least one of the connecting gate lines has the same polarity as the pad and is connected to the pad, and at least one row of the same polarity collector gate lines are connected to each other.

3. The back-contact solar cell according to claim 1, characterized in that, In each of the said break regions, at least one row of the said opposite polarity collector grid lines has an isolation break.

4. The back-contact solar cell according to claim 3, characterized in that, In each of the aforementioned break regions, the number of isolation breaks is A, the number of connecting gate lines is B, the number of pads is Z, and the number of rows of collector gate lines is C, satisfying the following relationship: B ≤ C ≤ Z ≤ A; and / or, The number of rows of the collector grid is greater than or equal to 180 rows and less than or equal to 600 rows; and / or, The number of pads in the same fracture area is multiple, and the multiple pads are arranged in a pad group at intervals along the second direction, with the number of pad groups being 10 to 60.

5. The back-contact solar cell according to claim 1, characterized in that, The width of the widest part of the connecting grid line along the second direction is W1, and the width of the collector grid line along the second direction is W2, satisfying the following relationship: W1 > W2; The second direction is perpendicular to the first direction.

6. The back-contact solar cell according to claim 5, characterized in that, Along the first direction, the width of the middle part of the connecting gate line is W3, and the width of the end of the connecting gate line is W1, satisfying the following relationship: W1 > W3.

7. The back-contact solar cell according to claim 6, characterized in that, The connecting grid lines include: A first connecting sub-gate line, the first connecting sub-gate line extending along the first direction, and the dimension of the first connecting sub-gate line along the second direction being W3; and Two second connecting sub-gate lines are provided at each end of the first connecting sub-gate line along the first direction, and the second connecting sub-gate lines extend along the second direction; the dimension of the second connecting sub-gate line along the second direction is W1.

8. The back-contact solar cell according to claim 6, characterized in that, Along the second direction, the spacing between two adjacent rows of collector grid lines of the same polarity is D1, satisfying the following relationship: 0.01×D1≤W3≤0.1×D1; and / or, 0.05×D1≤W1≤0.4×D1; and / or, 0.5×D1≤L≤1.8×D1; where L is the length of the connecting gate line along the first direction; 0.2×L≤D2≤0.9×L; where D2 is the spacing between two adjacent collector grid lines in the same row.

9. The back-contact solar cell according to any one of claims 1 to 8, characterized in that, The battery body includes: A silicon substrate having a backlight surface; A first doped layer and a second doped layer with opposite doping types, the first doped layer and the second doped layer being alternately spaced along the second direction on the backlight surface; and A functional film is disposed at least on the side of the first doped layer opposite to the silicon substrate and on the side of the second doped layer opposite to the silicon substrate; In this configuration, one type of collector gate line penetrates the functional film to form an ohmic contact with the first doped layer, and the other type of collector gate line penetrates the functional film to form an ohmic contact with the second doped layer; the pads and the connecting gate lines are both disposed on the side of the functional film away from the silicon substrate.

10. The back-contact solar cell according to any one of claims 1 to 8, characterized in that, The smoothing factor of the collector grid is less than 1 and greater than 0.

01.

11. A printing screen assembly, characterized in that, The printing screen assembly includes: A first printing screen has multiple rows of collector grid printing slots. Each row of collector grid printing slots includes multiple collector grid printing slots spaced apart along a third direction, where the third direction is the length direction of the collector grid printing slots. The multiple rows of collector grid printing slots are spaced apart in multiple columns along a fourth direction, and the multiple columns of collector grid printing slots are spaced apart along the third direction, so that there are discontinuous regions between adjacent columns of collector grid printing slots. The number of discontinuous regions is multiple. The fourth direction intersects with the third direction. The second printing screen is provided with pad printing grooves and connecting grid printing grooves spaced apart from the pad printing grooves.

12. A photovoltaic module, characterized in that, Includes several electrically connected back-contact solar cells; At least one of the back-contact solar cells is the back-contact solar cell according to any one of claims 1 to 10; Alternatively, at least one of the back-contact solar cell's current collector lines, pads, and connecting lines is printed using the screen printing assembly of claim 11.

Images