Back contact solar cells, modules and photovoltaic systems

Abstract

The application discloses a back contact solar cell, a module and a photovoltaic system, and relates to the field of silicon solar cells. The back contact solar cell comprises a silicon substrate, a first edge main grid, a first grid line, a second grid line, a first connecting area, a second connecting area, a first edge collecting grid line and a first connecting line. The first grid line comprises a first collecting grid line and a first bus grid line, and the first bus grid line is provided with a first main grid bridge at one end close to the first edge main grid; the first connecting area comprises a first edge connecting area closest to the first edge, the first edge collecting grid line and the first connecting line are arranged between the first edge connecting area and the first edge main grid, and the first edge collecting grid line extends along a first direction; the first connecting line extends along a second direction, is connected with at least two first edge collecting grid lines, and is connected with the first main grid bridge. The application can improve the conversion efficiency.

Description

Technical Field

[0001] This invention relates to the field of silicon solar cells, and more particularly to a back-contact solar cell, module, and photovoltaic system. Background Technology

[0002] Back-contact solar cells have alternating grid lines on their back side. To collect charge carriers near the edge, an edge grid is often placed near the edge. However, the edge grid has a different polarity than the nearest solder strip, resulting in a long carrier transport distance and high transport loss. Moreover, irregularly shaped charge carriers near the edge grid also tend to travel a long distance, leading to high transport loss and reduced conversion efficiency. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a back-contact solar cell, module and photovoltaic system, which can improve edge carrier collection efficiency and improve conversion efficiency.

[0004] To address the above problems, this invention discloses a back-contact solar cell, comprising: A silicon substrate includes a light-receiving surface and a back-lighting surface disposed opposite to each other; the back-lighting surface has a first edge and a second edge disposed opposite to each other in a first direction; The first edge main gate is located at the first edge; A plurality of first grid lines and a plurality of second grid lines are disposed on the backlight surface. The first grid lines and the second grid lines are alternately arranged along a second direction and extend along a first direction, and the first direction and the second direction intersect. The first grid line includes a first collection grid line and a first busbar grid line. The first busbar grid line has a first main grid bridge at one end near the first edge main grid. A plurality of first connection areas and a plurality of second connection areas are disposed on the backlight surface. The first connection areas and second connection areas are alternately arranged along a first direction and extend along a second direction. The first connection area includes a first edge connection area closest to the first edge. No second connection area is provided between the first edge connection area and the first edge main gate. The solder strip located in the first edge connection area is electrically connected to the first edge main gate. A plurality of first edge collecting grid lines and a first connecting line are disposed between the first edge connecting area and the first edge main grid. The first edge collecting grid lines extend along the first direction. The first connecting line extends along the second direction and is connected to at least two of the first edge collecting grid lines and to the first main grid bridge.

[0005] As an improvement to the above technical solution, the area of ​​at least one first main grid bridge in the back contact solar cell conforms to the following relationship:

[0006] In the formula, S z,i Let S be the area of ​​the i-th first main gate bridge. e,i S is the area of ​​the first connecting line connected to the i-th first main gate bridge. x,i Let n be the area of ​​a single first edge collection grid line electrically connected to the i-th first main grid bridge via the first connection line, and n be the total number of first edge collection grid lines electrically connected to the i-th first main grid bridge via the first connection line.

[0007] As an improvement to the above technical solution, n≤20.

[0008] As an improvement to the above technical solution, the value of n ranges from 3 to 8.

[0009] As an improvement to the above technical solution, the width of the first main grid bridge is greater than the width of the first collection grid line, and the width of the first connecting line is greater than the width of the first edge collection grid line.

[0010] As an improvement to the above technical solution, the area of ​​at least one first connecting line in the back contact solar cell conforms to the following relationship:

[0011] In the formula, S e,i S is the area of ​​the first connecting line connected to the i-th first main gate bridge. x,i Let n be the area of ​​a single first edge collection grid line electrically connected to the i-th first main grid bridge via the first connection line, and n be the total number of first edge collection grid lines electrically connected to the i-th first main grid bridge via the first connection line.

[0012] As an improvement to the above technical solution, the first collecting grid line is interrupted at the first connection area, the first busbar grid line is continuous at the first edge connection area, and the first busbar grid line is interrupted at other first connection areas.

[0013] As an improvement to the above technical solution, the second connection area includes a second edge connection area, and only a first edge connection area is provided between it and the first edge main gate; The first main gate bridge is located between the second edge connection area and the first edge main gate, and its end near the second edge connection area extends into the second edge connection area.

[0014] As an improvement to the above technical solution, the first grid line includes a plurality of first sub-collection grid lines arranged at intervals, which are located below the first main grid bridge; the first sub-collection grid lines extend along a first direction; and multiple first sub-collection grid lines are arranged along the first direction.

[0015] As an improvement to the above technical solution, at least one first main grid bridge in the back contact solar cell conforms to the following relationship:

[0016] In the formula, S z,i Let S be the area of ​​the i-th first main gate bridge. e,i S is the area of ​​the first connecting line connected to the i-th first main gate bridge. x,i S represents the area of ​​a single first edge collection gate line electrically connected to the i-th first main gate bridge via the first connection line, where n is the total number of first edge collection gate lines electrically connected to the i-th first main gate bridge via the first connection line. y,i Let be the area of ​​a single first sub-collection grid line located below the i-th first main grid bridge, and k be the total number of first sub-collection grid lines located below the i-th first main grid bridge.

[0017] As an improvement to the above technical solution, the value of k ranges from 2 to 20.

[0018] As an improvement to the above technical solution, the first sub-collection grid line is staggered from the first edge connection area.

[0019] As an improvement to the above technical solution, the second grid line includes a second auxiliary collection grid line, which is disposed between the first connecting line and the first edge main grid line. One end of the second auxiliary collection grid line is connected to the first edge main grid line, and the other end is provided with a preset distance from the first connecting line. The second grid line located on the side of the first main grid bridge away from the second auxiliary collection grid line extends continuously to the first edge main grid.

[0020] As an improvement to the above technical solution, it also includes: The second edge main gate, which is located at the second edge; and A plurality of second edge collecting grid lines and a second connecting line are disposed between the second edge connecting area and the second edge main grid, the second edge collecting grid lines extending along the first direction; the second connecting line extends along the second direction and is connected to at least two second edge collecting grid lines; The second grid line includes a second collection grid line and a second busbar grid line, wherein the second busbar grid line has a second main grid bridge at one end near the second edge main grid line; the second connecting line is connected to the second main grid bridge. The second connection area includes a second edge connection area closest to the second edge. There is no first connection area between the second edge connection area and the second edge main gate. The solder strip located in the second edge connection area is electrically connected to the second edge main gate.

[0021] As an improvement to the above technical solution, the area of ​​at least one second main grid bridge in the back contact solar cell conforms to the following relationship:

[0022] In the formula, S γ,j Let S be the area of ​​the j-th second main gate bridge. δ,j S is the area of ​​the second connecting line connected to the j-th second main gate bridge. α,j Let μ be the area of ​​a single second edge collection grid line electrically connected to the j-th second main grid bridge via the second connection line, and let μ be the total number of second edge collection grid lines electrically connected to the j-th second main grid bridge via the second connection line.

[0023] As an improvement to the above technical solution, μ≤20.

[0024] As an improvement to the above technical solution, the value of μ ranges from 3 to 8.

[0025] As an improvement to the above technical solution, the width of the second main grid bridge is greater than the width of the second collection grid line, and the width of the second connecting line is greater than the width of the second edge collection grid line.

[0026] As an improvement to the above technical solution, the area of ​​at least one second connecting line in the back contact solar cell conforms to the following relationship:

[0027] In the formula, S δ,j S is the area of ​​the second connecting line connected to the j-th second main gate bridge. α,j Let μ be the area of ​​a single second edge collection grid line electrically connected to the j-th second main grid bridge via the second connection line, and let μ be the total number of second edge collection grid lines electrically connected to the j-th second main grid bridge via the second connection line.

[0028] As an improvement to the above technical solution, the second collecting grid line is discontinuous at the second connection area, the second bus grid line is continuous at the second edge connection area, and the second bus grid line is discontinuous at other second connection areas.

[0029] As an improvement to the above technical solution, the first connection area includes a first edge connection area, and only a second edge connection area is provided between it and the second edge main gate; The second main gate bridge is located between the first edge connection area and the second edge main gate, and its end near the first edge connection area extends into the first edge connection area.

[0030] As an improvement to the above technical solution, the second grid line further includes a plurality of second sub-collection grid lines arranged at intervals, which are located below the second main grid bridge; the second sub-collection grid lines extend along the first direction; and multiple second sub-collection grid lines are arranged along the first direction.

[0031] As an improvement to the above technical solution, the area of ​​at least one second main grid bridge in the back contact solar cell conforms to the following relationship:

[0032] In the formula, S γ,j Let S be the area of ​​the j-th second main gate bridge. δ,j S is the area of ​​the second connecting line connected to the j-th second main gate bridge. α,j S represents the area of ​​a single second edge collection gate line electrically connected to the j-th second main gate bridge via the second connection line, μ represents the total number of second edge collection gate lines electrically connected to the j-th second main gate bridge via the second connection line, and S represents the area of ​​a single second edge collection gate line electrically connected to the j-th second main gate bridge via the second connection line. β,j Let λ be the area of ​​a single second sub-collection grid line located below the j-th second main grid bridge, and let λ be the total number of second sub-collection grid lines located below the i-th second main grid bridge.

[0033] As an improvement to the above technical solution, the value of λ ranges from 2 to 20.

[0034] As an improvement to the above technical solution, the second sub-collection grid line is staggered from the second edge connection area.

[0035] As an improvement to the above technical solution, the first grid line includes a first auxiliary collection grid line, which is disposed between the second connecting line and the second edge main grid line. One end of the first auxiliary collection grid line is connected to the second edge main grid line, and the other end is provided with a preset distance from the second connecting line. The first grid line located on the side of the second main grid bridge away from the first auxiliary collection grid line extends to the second edge main grid.

[0036] Accordingly, the present invention also discloses a battery assembly comprising the aforementioned back-contact solar cell or segments cut from it.

[0037] Accordingly, the present invention also discloses a photovoltaic system comprising the aforementioned battery assembly.

[0038] Implementing this invention has the following beneficial effects: In one embodiment of the present invention, a back-contact solar cell includes a silicon substrate, a first edge main grid, a first grid line, a second grid line, a first connection region, a second connection region, a first edge collection grid line, and a first connecting line. The first grid line includes a first collection grid line and a first bus grid line, and the first bus grid line has a first main grid bridge at one end near the first edge main grid. The first connection region includes a first edge connection region closest to the first edge. The first edge collection grid line and the first connecting line are disposed between the first edge connection region and the first edge main grid. The first edge collection grid line extends along a first direction. The first connecting line extends along a second direction and is connected to at least two of the first edge collection grid lines and to the first main grid bridge. Based on the above technical solutions, firstly, the solder strip located in the first edge connection area has the same polarity as the edge main gate, shortening the transmission path of edge electrons, reducing transmission loss, and improving conversion efficiency; secondly, by introducing the first main gate bridge, the first edge collection gate line, and the first connecting line, the collection efficiency of carriers with opposite polarities to the edge main gate is enhanced, improving conversion efficiency; thirdly, the first main gate bridge enhances the transmission of carriers collected by the first edge collection gate line, reducing transmission resistance and avoiding current loss due to excessive transmission resistance, thus improving conversion efficiency; fourthly, the first main gate bridge uses main gate paste printing, which has a large width, i.e., a large cross-sectional area, resulting in a larger Ag-Sn layer formed after the solder strip contacts the first main gate bridge, which is beneficial for carrier transmission, and the main gate paste has relatively low corrosiveness to the solder strip, improving the reliability of the back contact battery. Attached Figure Description Figure 1 This is a schematic diagram of the back structure of a back-contact solar cell in one embodiment of the present invention; Figure 2 yes Figure 1 A magnified view of a section at point A in the middle; Figure 3 yes Figure 1 A magnified view of a section at point B in the middle; Figure 4 yes Figure 1 A schematic diagram of the cross-sectional structure of the back contact solar cell along line MM; Figure 5 This is a schematic diagram of the system composition of a battery assembly according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the composition of a photovoltaic system in one embodiment of the present invention; In the diagram, 1 represents the photovoltaic system, 10 represents the back-contact cell module, 100 represents the silicon substrate, 110 represents the first edge, 120 represents the second edge, 130 represents the backlight surface, 131 represents the first doped layer, 132 represents the second doped layer, 140 represents the light-receiving surface, 150 represents the passivation layer, 200 represents the first edge main grid, 300 represents the first grid line, 310 represents the first collection grid line, 320 represents the first busbar grid line, 321 represents the first main grid bridge, 330 represents the first sub-collection grid line, 340 represents the first auxiliary collection grid line, and 410 represents the first edge collection grid line. 420 is the first connecting line, 500 is the first connecting area, 510 is the first edge connecting area, 520 is the first edge connecting area, 600 is the second connecting area, 610 is the second edge connecting area, 620 is the second edge connecting area, 700 is the second grid line, 710 is the second collection grid line, 720 is the second bus grid line, 721 is the second main grid bridge, 730 is the second sub-collection grid line, 740 is the second auxiliary collection grid line, 810 is the second edge collection grid line, 820 is the second connecting line, and 900 is the second edge main grid. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0040] In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0042] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0043] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0044] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0045] Please see Figures 1-4 An embodiment of the present invention discloses a back-contact solar cell, which includes a silicon substrate 100, a plurality of first grid lines 300, a plurality of second grid lines 700, a first edge main grid 200, a plurality of first connection regions 500, a plurality of second connection regions 600, a plurality of first edge collection grid lines 410 and a first connection line 420.

[0046] Among them, such as Figure 4As shown, the silicon substrate 100 can be P-type or N-type single-crystal silicon, but is not limited to these. In terms of thickness, the silicon substrate 100 includes a light-receiving surface 140 and a back-lighting surface 130 disposed opposite each other. The light-receiving surface 140 generally refers to the side that receives light, and its surface may also be provided with common materials in the art such as a passivation layer 150 and an anti-reflection layer, but is not limited to these. The back-lighting surface 130 mainly comprises a doped layer, a passivation layer 150, and electrode structures. It should be noted that in some embodiments, the back-lighting surface 130 can also absorb light incident through it, thereby generating a photocurrent.

[0047] The silicon substrate 100 may be circular, hexagonal, octagonal, or rectangular, but is not limited thereto. Preferably, in some embodiments, the silicon substrate 100 is rectangular, with chamfered corners, and has a first edge 110 and a second edge 120 disposed opposite to each other in a first direction.

[0048] Specifically, a first doped layer 131 and a second doped layer 132 are disposed on the backlight surface 130 of the silicon substrate 100. The first doped layer 131 and the second doped layer 132 are alternately arranged along a second direction and extend along a first direction. A gap region is provided between the first doped layer 131 and the second doped layer 132 to achieve insulation between the first doped layer 131 and the second doped layer 132. The first doped layer 131 may be one or more of a P-type doped polycrystalline silicon layer, a P-type doped amorphous silicon layer, or a P-type doped microcrystalline silicon layer, but is not limited thereto. Preferably, the first doped layer 131 is a P-type polycrystalline silicon layer. The second doped layer 132 may be an N-type doped polycrystalline silicon layer, an N-type doped amorphous silicon layer, or an N-type doped microcrystalline silicon layer, but is not limited thereto. Preferably, it is an N-type doped polycrystalline silicon layer.

[0049] like Figures 1-4 As shown, the first gate line 300 and the second gate line 700 are arranged alternately along the second direction and extend along the first direction. The first gate line 300 is in contact with the first doped layer 131, and the second gate line 700 is in contact with the second doped layer 132. It can be understood that one of the first gate line 300 and the second gate line 700 is a positive gate line and the other is a negative gate line. The first edge main gate 200 is disposed at the first edge 110 and is electrically connected to the second gate line 700.

[0050] Specifically, please refer to Figure 1 , Figure 3 A plurality of first connection regions 500 and a plurality of second connection regions 600 are arranged alternately along a first direction; the first grid line 300 and the second grid line 700 are both intersected with the first connection regions 500 and the second connection regions 600; the first connection regions 500 and the second connection regions 600 are used to form solder strips to electrically connect different back contact solar cells or their cut pieces to form a cell string, and then the cell string forms a cell module and a photovoltaic system.

[0051] Specifically, the first connection region 500 includes a first edge connection region 510 closest to the first edge 110, and there is no second connection region 600 between the first edge connection region 510 and the first edge 110. Furthermore, the solder strip located within the first edge connection region 510 is electrically connected to the first edge main gate 200. That is, the solder strip located in the first edge connection region 510 and the first edge main gate 200 located at the first edge 110 are of the same polarity, which shortens the transmission path of edge carriers, reduces transmission loss, and improves conversion efficiency.

[0052] Specifically, in some embodiments, the first gate line 300 includes a first collecting gate line 310 and a first busbar gate line 320. The first collecting gate line 310 is mainly used to collect carriers, while the first busbar gate line 320 serves both to collect carriers and to connect carriers in part of the gate line. More specifically, the first busbar gate line 320 has a first main gate bridge 321 at one end near the first edge main gate 200. The first main gate bridge 321 is formed by printing and sintering the main gate paste. Since the main gate paste does not erode through the passivation layer 150 during the sintering process (i.e., it does not contact the first doped layer 131), it does not serve to collect carriers, but only to connect carriers.

[0053] Specifically, the back-contact solar cell also includes a plurality of first edge collection grid lines 410 and first connecting lines 420, both disposed between the first edge connection region 510 and the first edge main grid 200, to collect charge carriers from the doped layer between the first edge main grid 200 and the first edge connection region 510 that are dissimilar to the first edge main grid 200. Specifically, the first edge collection grid lines 410 extend along a first direction and contact the first doped layer 131 to achieve charge carrier collection. The first connecting lines 420 extend along a second direction and are connected to at least two first edge collection grid lines 410, and are also connected to the first main grid bridge 321. That is, the edge carriers collected by the first edge collection grid lines 410 are collected by the first connecting lines 420 and then transported to the first main grid bridge 321. Based on this, the carrier collection efficiency is improved, the fill factor is improved, and the conversion efficiency is improved. At the same time, the first main grid bridge 321 effectively reduces the transmission resistance, which also effectively improves the conversion efficiency. Preferably, in some embodiments, the first connecting line 420 does not contact the second doped layer 132.

[0054] Preferably, in some embodiments, the area of ​​at least one first main grid bridge in the back-contact solar cell conforms to the following relationship:

[0055] In the formula, S z,i Let S be the area of ​​the i-th first main gate bridge 321. e,iS is the area of ​​the first connecting line 420 connected to the i-th first main gate bridge 321. x,i The area of ​​a single first edge collection gate line 410 electrically connected to the i-th first main gate bridge 321 via the first connection line 420 is denoted by n, where n is the total number of first edge collection gate lines 410 electrically connected to the i-th first main gate bridge 321 via the first connection line 420. Based on the above implementation, the transmission loss of edge carriers can be significantly reduced, and the conversion efficiency can be improved. It should be noted that the area of ​​each gate line in this invention refers to its area projected onto the silicon substrate. Taking the i-th first main gate bridge 321 as an example, its area S is... z,i The area of ​​its orthographic projection on the silicon substrate 100 is the product of the length and width of the rectangle if the orthographic projection is rectangular.

[0056] Preferably, in some embodiments, the width of the first main grid bridge 321 is greater than the width of the first collection grid line 310 and also greater than the width of the first connecting line 420, and the width of the first connecting line 420 is greater than the width of the first edge collection grid line 410. Based on this, the carrier transport resistance can be reduced, thereby reducing energy loss of carriers during transport and further improving the fill factor and conversion efficiency of the battery.

[0057] Specifically, in some implementations, the width of the first main gate bridge 321 is 150μm to 1000μm, exemplarily 300μm, 450μm, 600μm, 750μm, 900μm or 950μm, but not limited thereto.

[0058] Specifically, in some implementations, the width of the first edge collecting grid line 410 is 10μm to 40μm, exemplarily 15μm, 20μm, 25μm, 30μm or 35μm, but not limited thereto.

[0059] Specifically, in some implementations, n ≤ 20, meaning the number of first edge collection grid lines 410 is ≤ 20. If the number of first edge collection grid lines 410 is too large, the width of the first main grid bridge 321 and the first connecting line 420 needs to be increased accordingly, resulting in a large light-blocking area, which is not conducive to improving conversion efficiency. Preferably, the value of n is in the range of 2 to 15, exemplarily 3, 5, 7, 9, 11, or 13, but not limited to these. More preferably, the value of n is in the range of 2 to 10, and even more preferably 3 to 8. When the value of n is between 3 and 8, the light-blocking area and carrier collection efficiency can be effectively balanced.

[0060] Specifically, in some implementations, the width of the first connecting line 420 is 50μm to 200μm, exemplarily 70μm, 90μm, 110μm, 130μm, 150μm or 170μm, but is not limited thereto.

[0061] Preferably, in some embodiments, at least one first connecting wire 420 in the back contact solar cell conforms to the following relationship:

[0062] In the formula, S e,i S is the area of ​​the first connecting line 420 connected to the i-th first main gate bridge 321. x,i The area of ​​a single first edge collection grid line 410 electrically connected to the i-th first main grid bridge 321 via the first connection line 420 is denoted by n, where n is the total number of first edge collection grid lines 410 electrically connected to the i-th first main grid bridge 321 via the first connection line 420. Based on this, transmission loss can be further reduced and conversion efficiency improved.

[0063] Specifically, in some embodiments, at the first edge connection region 510, the first collecting grid line 310 is discontinuous, while the first bus grid line 320 is continuous, forming a continuous conductive path in this region to discharge the charge carriers collected by the first edge collecting grid line 410. It is understood that multiple first connection regions 500 are provided on the back contact solar cell, the first collecting grid line 310 is discontinuous at each of the first connection regions 500, and the first bus grid line 320 is discontinuous at all other first connection regions 500 except the first edge connection region 510. This design effectively reduces the height of the insulating adhesive, reduces the height difference of the solder strip, and improves the reliability of the battery module.

[0064] Specifically, please refer to Figure 1 , Figure 3 In some embodiments, the second connection region 600 includes a second edge connection region 620, which is disposed near the first edge 110, and only the first edge connection region 510 is provided between it and the first edge main gate 200; the first main gate bridge 321 is disposed between the second edge connection region 620 and the first edge main gate 200, and its end near the second edge connection region 620 extends into the second edge connection region 620. Based on this, the length of the first main gate bridge 321 can be controlled within a specific range to prevent the first main gate bridge 321 from affecting carrier collection and conversion efficiency. At the same time, it also ensures that the first main gate bridge 321 has better transmission performance, which facilitates the effective export of carriers collected by the first edge collection gate line 410.

[0065] Preferably, in some embodiments, the first gate line 300 includes a plurality of first sub-collection gate lines 330 arranged at intervals, which are disposed below the first main gate bridge 321; the first sub-collection gate lines 330 extend along a first direction. The first sub-collection gate lines 330 are in contact with the first doped layer 131 below them. Based on this, carriers in the first doped layer 131 below the first main gate bridge 321 can be collected by the first sub-collection gate lines 330, thereby improving the conversion efficiency.

[0066] Specifically, multiple first sub-collecting grid lines 330 are distributed uniformly or unevenly along a first direction below the first main grid bridge 321. Preferably, in some embodiments, the spacing between the multiple first sub-collecting grid lines 330 is different, and the first sub-collecting grid lines 330 are staggered from the first edge connection area 510. Based on this, it can effectively prevent the padding of irregular solder strips and further improve the reliability of the battery assembly.

[0067] Preferably, based on the above embodiments, at least one first main grid bridge 321 in the back contact solar cell conforms to the following relationship:

[0068] In the formula, S z,i Let S be the area of ​​the i-th first main gate bridge 321. e,i S is the area of ​​the first connecting line 420 connected to the i-th first main gate bridge 321. x,i S represents the area of ​​a single first edge collecting grid line 410 electrically connected to the i-th first main grid bridge 321 via the first connecting line 420, where n is the total number of first edge collecting grid lines 410 electrically connected to the i-th first main grid bridge 321 via the first connecting line 420. y,i Let be the area of ​​a single first sub-collection grid line 330 located below the i-th first main grid bridge 321, and k be the total number of first sub-collection grid lines 330 located below the i-th first main grid bridge 321. Based on this, transmission loss can be effectively reduced and conversion efficiency improved.

[0069] Specifically, in some implementations, the width of the first sub-collection gate line 330 is 10μm to 40μm, exemplarily 15μm, 20μm, 25μm, 30μm or 35μm, but not limited thereto.

[0070] Specifically, in some implementations, k ≤ 20, meaning the number of the first sub-collecting grid lines 330 is ≤ 20. If the number of the first sub-collecting grid lines 330 is too large, the width of the first main grid bridge 321 needs to be increased accordingly, resulting in a large light-blocking area, which is not conducive to improving conversion efficiency. Preferably, the value of k is in the range of 2 to 20, exemplarily 3, 5, 7, 9, 11, 13, 15, or 17, but not limited to these. More preferably, the value of k is in the range of 2 to 5, and even more preferably 2 to 3.

[0071] Preferably, in some embodiments, the second gate line 700 includes a second auxiliary collection gate line 740, which is disposed between the first connecting line 420 and the first edge main gate 200. One end of the auxiliary collection gate line 740 is connected to the first edge main gate 200, and the other end is spaced at a predetermined distance from the first connecting line 420. The second gate line 700, located on the side of the first main gate bridge 321 opposite to the second auxiliary collection gate line 740, extends continuously to the first edge main gate 200. Based on this, carriers with different polarities from those collected by the first edge main gate 200 at the first edge 110 can be collected, further improving the conversion efficiency.

[0072] Specifically, please refer to Figure 1 , Figure 3 In some embodiments, the second edge main gate 900 is located at the second edge 120 and is electrically connected to the first gate line 300. The second connection region 600 includes a second edge connection region 610 closest to the second edge 120. There is no first connection region 500 between the second edge connection region 610 and the second edge 120, and the solder strip located in the second edge connection region 610 is electrically connected to the second edge main gate 900. That is, the solder strip located in the second edge connection region 610 and the second edge main gate 900 located at the second edge 120 are of the same polarity, which shortens the transmission path of edge carriers, reduces transmission loss, and improves conversion efficiency.

[0073] Specifically, in some embodiments, the second gate line 700 includes a second collecting gate line 710 and a second bus gate line 720. The second collecting gate line 710 is mainly used to collect carriers and is in contact with the second doped layer 132 below it. The second bus gate line 720 serves both to collect carriers and to connect carriers in part of the gate line. More specifically, the second bus gate line 720 has a second main gate bridge 721 at one end near the second edge main gate 900. This second main gate bridge 721 is formed by printing and sintering the main gate paste. Since the main gate paste does not erode through the passivation layer 150 during the sintering process, it does not serve to collect carriers but only to connect them.

[0074] Specifically, the back-contact solar cell also includes a plurality of second edge collection grid lines 810 and second connecting lines 820, both disposed between the second edge connection region 610 and the second edge main grid 900, to collect charge carriers from the heterogeneous doped layer between the second edge main grid 900 and the second edge connection region 610. Specifically, the second edge collection grid lines 810 extend along a first direction and contact the second doped layer 132 beneath them. The second connecting lines 820 extend along a second direction and are connected to at least two second edge collection grid lines 810, and are also connected to the second main grid bridge 721. That is, the edge carriers collected by the second edge collection grid lines 810 are collected by the second connecting lines 820 and then transported to the second main grid bridge 721. Based on this, the carrier collection efficiency is improved, the fill factor is increased, and the conversion efficiency is improved. Simultaneously, the second main grid bridge 721 effectively reduces the transmission resistance, which also effectively improves the conversion efficiency.

[0075] Preferably, in some embodiments, at least one second main grid bridge 721 in the back-contact solar cell conforms to the following relationship:

[0076] In the formula, S γ,j S is the area of ​​the j-th second main gate bridge 721. δ,j S is the area of ​​the second connecting line 820 connected to the j-th second main gate bridge 721. α,j The area of ​​a single second edge collection grid line 810 electrically connected to the j-th second main grid bridge 721 via the second connection line 820 is given by μ, and the total number of second edge collection grid lines electrically connected to the j-th second main grid bridge 721 via the second connection line 820 is given by μ.

[0077] Preferably, in some embodiments, the width of the second main grid bridge 721 is greater than the width of the second collection grid line 710 and also greater than the width of the second connecting line 820, and the width of the second connecting line 820 is greater than the width of the second edge collection grid line 810. Based on this, the carrier transport resistance can be reduced, thereby reducing energy loss of carriers during transport and further improving the fill factor and conversion efficiency of the battery.

[0078] Specifically, in some implementations, the width of the second main gate bridge 721 is 150μm to 1000μm, exemplarily 300μm, 450μm, 600μm, 750μm, 900μm or 950μm, but not limited thereto.

[0079] Specifically, in some implementations, the width of the second edge collection grid line 810 is 10μm to 40μm, exemplarily 15μm, 20μm, 25μm, 30μm or 35μm, but not limited thereto.

[0080] Specifically, in some implementations, μ ≤ 20, meaning the number of second edge collection grid lines 810 is ≤ 20. If the number of second edge collection grid lines 810 is too large, the width of the second main grid bridge 721 and the second connecting line 820 needs to be increased accordingly, resulting in a large light-shielding area, which is not conducive to improving conversion efficiency. Preferably, the value of μ ranges from 2 to 15, exemplarily 3, 5, 7, 9, 11, or 13, but is not limited thereto. More preferably, the value of μ ranges from 2 to 10, and even more preferably from 3 to 8. When the value of μ is between 3 and 8, the light-shielding area and carrier collection efficiency can be effectively balanced.

[0081] Specifically, in some implementations, the width of the second connecting line 820 is 50μm to 200μm, exemplarily 70μm, 90μm, 110μm, 130μm, 150μm or 170μm, but is not limited thereto.

[0082] Preferably, in some embodiments, at least one second connecting wire 820 in the back contact solar cell conforms to the following relationship:

[0083] In the formula, S δ,j S is the area of ​​the second connecting line 820 connected to the j-th second main gate bridge 721. α,j The area of ​​a single second edge collection grid line 810 electrically connected to the j-th second main grid bridge 721 via the second connection line 820 is given by μ, where μ is the total number of second edge collection grid lines 810 electrically connected to the j-th second main grid bridge 721 via the second connection line 820. Based on this, transmission loss can be further reduced and conversion efficiency improved.

[0084] Specifically, in some embodiments, at the second edge connection region 610, the second collecting grid line 710 is discontinuous, while the second bus grid line 720 is continuous, forming a continuous conductive path in this region to discharge the carriers collected by the second edge collecting grid line 710. It is understood that multiple second connection regions 600 are provided on the back contact solar cell, the second collecting grid line 710 is discontinuous at each of the second connection regions 600, and the second bus grid line 720 is discontinuous at all other second connection regions 600 except for the second edge connection region 610. This design effectively reduces the height of the insulating adhesive, reduces the height difference of the solder strip, and improves the reliability of the battery module.

[0085] Specifically, in some embodiments, the first connection region 500 includes a first edge connection region 520, which is disposed near the second edge 120, and only a second edge connection region 610 is provided between it and the second edge main gate 900; the second main gate bridge 721 is disposed between the first edge connection region 520 and the second edge main gate 900, and its end near the first edge connection region 520 extends into the first edge connection region 520. Based on this, the length of the second main gate bridge 721 can be controlled within a specific range to prevent the second main gate bridge 721 from affecting carrier collection and conversion efficiency. At the same time, it also ensures that the second main gate bridge 721 has better transmission performance, which facilitates the effective export of carriers collected by the second edge collection gate line 810.

[0086] Preferably, in some embodiments, the second gate line 700 includes a plurality of spaced-apart second sub-collection gate lines 730 disposed below the second main gate bridge 721; the second sub-collection gate lines 730 extend along a first direction; and multiple second sub-collection gate lines 730 are arranged along the first direction. The second sub-collection gate lines 730 are in contact with the doped layer below them, thereby collecting carriers in the doped layer below the second main gate bridge 721 through the second sub-collection gate lines 730, improving the conversion efficiency.

[0087] Specifically, multiple second sub-collection grid lines 730 are distributed uniformly or unevenly below the second main grid bridge 721 along the first direction. Preferably, in some embodiments, the spacing between the multiple second sub-collection grid lines 730 is different, and the second sub-collection grid lines 730 are staggered from the second edge connection area 610. Based on this, it can effectively prevent the padding of irregular solder strips and further improve the reliability of the battery assembly.

[0088] Preferably, based on the above embodiments, at least one second main grid bridge 721 in the back contact solar cell conforms to the following relationship:

[0089] In the formula, S γ,j S is the area of ​​the j-th second main gate bridge 721. δ,j S is the area of ​​the second connecting line 820 connected to the j-th second main gate bridge 721. α,j S represents the area of ​​a single second edge collection grid line 810 electrically connected to the j-th second main grid bridge 721 via the second connection line 820, μ represents the total number of second edge collection grid lines 810 electrically connected to the j-th second main grid bridge 721 via the second connection line 820, and S represents the area of ​​a single second edge collection grid line 810 electrically connected to the j-th second main grid bridge 721 via the second connection line 820. β,j Let λ be the area of ​​a single second sub-collection grid line 730 located below the j-th second main grid bridge 721, and λ be the total number of second sub-collection grid lines 730 located below the i-th second main grid bridge 721. Based on this, transmission loss can be effectively reduced and conversion efficiency improved.

[0090] Specifically, in some implementations, the width of the second sub-collection gate line 730 is 10μm to 40μm, exemplarily 15μm, 20μm, 25μm, 30μm or 35μm, but not limited thereto.

[0091] Specifically, in some implementations, λ ≤ 20, meaning the number of second sub-collecting grid lines 730 is ≤ 20. If the number of second sub-collecting grid lines 730 is too large, the width of the second main grid bridge 721 needs to be increased accordingly, resulting in a large light-blocking area, which is not conducive to improving conversion efficiency. Preferably, the value of λ is in the range of 2 to 20, exemplarily 3, 5, 7, 9, 11, 13, 15, or 17, but not limited to these. More preferably, the value of λ is in the range of 2 to 5, and even more preferably 2 to 3.

[0092] Preferably, in some embodiments, the first gate line 300 includes a first auxiliary collection gate line 340, which is disposed between the second connecting line 820 and the second edge main gate 900. One end of the auxiliary collection gate line 340 is connected to the second edge main gate 900, and the other end is spaced at a predetermined distance from the second connecting line 820. The first gate line 300 located on the side of the second main gate bridge 721 away from the first auxiliary collection gate line 340 extends continuously to the second edge main gate 900. Based on this, carriers with different polarities from those collected by the second edge 120 and the second edge main gate 900 can be collected, further improving the conversion efficiency.

[0093] Accordingly, please refer to Figure 5 This application also discloses a battery module 10, which includes the aforementioned back-contact solar cell 100. Specifically, battery strings can be formed from the aforementioned back-contact solar cell 100 or its sliced ​​segments, and multiple battery strings can be combined to form the battery module 10. Specifically, multiple battery strings can be connected in series or in parallel through busbars, solder strips, or other conductive media to form the battery module 10. In addition, for the mechanical connection of multiple battery strings, and other usage requirements of the module (such as the electrical connection of multiple battery modules 10, weather resistance, etc.), it is necessary to introduce components such as insulating adhesive, junction boxes, frames, back plates, films, and glass, but not limited to these.

[0094] Accordingly, please refer to Figure 6This application also discloses a photovoltaic system 1, which includes the aforementioned battery module 10. In this embodiment, the photovoltaic system 1 can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants, and can also be applied to equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, solar buildings, etc. Of course, it is understood that the application scenarios of the photovoltaic system 1 are not limited to these, that is to say, the photovoltaic system 1 can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system 11 may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules 10. For example, multiple battery modules 10 can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to realize solar power supply.

[0095] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with the described embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0096] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A back-contact solar cell, characterized in that, include: A silicon substrate includes a light-receiving surface and a back-lighting surface disposed opposite to each other; the back-lighting surface has a first edge and a second edge disposed opposite to each other in a first direction; The first edge main gate is located at the first edge; A plurality of first grid lines and a plurality of second grid lines are disposed on the backlight surface. The first grid lines and the second grid lines are alternately arranged along a second direction and extend along a first direction, and the first direction and the second direction intersect. The first grid line includes a first collection grid line and a first busbar grid line. The first busbar grid line has a first main grid bridge at one end near the first edge main grid. A plurality of first connection areas and a plurality of second connection areas are disposed on the backlight surface. The first connection areas and the second connection areas are alternately arranged along a first direction and extend along a second direction. The first connection area includes a first edge connection area closest to the first edge. There is no second connection area between the first edge connection area and the first edge main gate. The solder strip located in the first edge connection area is electrically connected to the first edge main gate. as well as A plurality of first edge collecting grid lines and a first connecting line are disposed between the first edge connecting area and the first edge main grid. The first edge collecting grid lines extend along the first direction. The first connecting line extends along the second direction and is connected to at least two of the first edge collecting grid lines and to the first main grid bridge.

2. The back-contact solar cell as described in claim 1, characterized in that, The area of ​​at least one first main grid bridge in the back contact solar cell conforms to the following relationship: In the formula, S z,i Let S be the area of ​​the i-th first main gate bridge. e,i S is the area of ​​the first connecting line connected to the i-th first main gate bridge. x,i Let n be the area of ​​a single first edge collection grid line electrically connected to the i-th first main grid bridge via the first connection line, and n be the total number of first edge collection grid lines electrically connected to the i-th first main grid bridge via the first connection line.

3. The back-contact solar cell as described in claim 2, characterized in that, n≤20。 4. The back-contact solar cell as described in claim 2, characterized in that, The value of n ranges from 3 to 8.

5. The back-contact solar cell as described in claim 1, characterized in that, The width of the first main grid bridge is greater than the width of the first collection grid line, and the width of the first connecting line is greater than the width of the first edge collection grid line.

6. The back-contact solar cell as described in claim 1, characterized in that, The area of ​​at least one first connecting wire in the back contact solar cell conforms to the following relationship: In the formula, S e,i S is the area of ​​the first connecting line connected to the i-th first main gate bridge. x,i Let n be the area of ​​a single first edge collection grid line electrically connected to the i-th first main grid bridge via the first connection line, and n be the total number of first edge collection grid lines electrically connected to the i-th first main grid bridge via the first connection line.

7. The back-contact solar cell as described in claim 1, characterized in that, The first collecting grid line is interrupted at the first connection area, the first bus grid line is continuous at the first edge connection area, and the first bus grid line is interrupted at other first connection areas.

8. The back-contact solar cell as described in claim 1, characterized in that, The second connection area includes a second edge connection area, and only a first edge connection area is provided between it and the first edge main gate; The first main gate bridge is located between the second edge connection area and the first edge main gate, and its end near the second edge connection area extends into the second edge connection area.

9. The back-contact solar cell according to any one of claims 1 to 8, characterized in that, The first grid line includes a plurality of first sub-collection grid lines arranged at intervals, which are located below the first main grid bridge; the first sub-collection grid lines extend along a first direction; and multiple first sub-collection grid lines are arranged along the first direction.

10. The back-contact solar cell as described in claim 9, characterized in that, At least one first main grid bridge in the back-contact solar cell conforms to the following relationship: In the formula, S z,i Let S be the area of ​​the i-th first main gate bridge. e,i S is the area of ​​the first connecting line connected to the i-th first main gate bridge. x,i S represents the area of ​​a single first edge collection gate line electrically connected to the i-th first main gate bridge via the first connection line, where n is the total number of first edge collection gate lines electrically connected to the i-th first main gate bridge via the first connection line. y,i Let be the area of ​​a single first sub-collection grid line located below the i-th first main grid bridge, and k be the total number of first sub-collection grid lines located below the i-th first main grid bridge.

11. The back-contact solar cell as described in claim 9, characterized in that, The value of k ranges from 2 to 20.

12. The back-contact solar cell as described in claim 9, characterized in that, The first sub-collection grid line is offset from the first edge connection area.

13. The back-contact solar cell as claimed in claim 1, characterized in that, The second grid line includes a second auxiliary collection grid line, which is disposed between the first connecting line and the first edge main grid line. One end of the second auxiliary collection grid line is connected to the first edge main grid line, and the other end is provided with a preset distance from the first connecting line. The second grid line located on the side of the first main grid bridge away from the second auxiliary collection grid line extends continuously to the first edge main grid.

14. The back-contact solar cell as claimed in claim 1, characterized in that, Also includes: The second edge main gate is located at the second edge; as well as A plurality of second edge collecting grid lines and a second connecting line are disposed between the second edge connecting area and the second edge main grid, the second edge collecting grid lines extending along the first direction; the second connecting line extends along the second direction and is connected to at least two second edge collecting grid lines; The second grid line includes a second collection grid line and a second busbar grid line, wherein the second busbar grid line has a second main grid bridge at one end near the second edge main grid line; the second connecting line is connected to the second main grid bridge. The second connection area includes a second edge connection area closest to the second edge. There is no first connection area between the second edge connection area and the second edge main gate. The solder strip located in the second edge connection area is electrically connected to the second edge main gate.

15. The back-contact solar cell as described in claim 14, characterized in that, The area of ​​at least one second main grid bridge in the back-contact solar cell conforms to the following relationship: In the formula, S γ,j Let S be the area of ​​the j-th second main gate bridge. δ,j S is the area of ​​the second connecting line connected to the j-th second main gate bridge. α,j Let μ be the area of ​​a single second edge collection grid line electrically connected to the j-th second main grid bridge via the second connection line, and let μ be the total number of second edge collection grid lines electrically connected to the j-th second main grid bridge via the second connection line.

16. The back-contact solar cell as described in claim 15, characterized in that, μ≤20.

17. The back-contact solar cell as claimed in claim 15, characterized in that, The value of μ ranges from 3 to 8.

18. The back-contact solar cell as claimed in claim 1, characterized in that, The width of the second main grid bridge is greater than the width of the second collection grid line, and the width of the second connecting line is greater than the width of the second edge collection grid line.

19. The back-contact solar cell as claimed in claim 15, characterized in that, The area of ​​at least one second connecting wire in the back contact solar cell conforms to the following relationship: In the formula, S δ,j S is the area of ​​the second connecting line connected to the j-th second main gate bridge. α,j Let μ be the area of ​​a single second edge collection grid line electrically connected to the j-th second main grid bridge via the second connection line, and let μ be the total number of second edge collection grid lines electrically connected to the j-th second main grid bridge via the second connection line.

20. The back-contact solar cell as claimed in claim 14, characterized in that, The second collecting grid line is discontinuous at the second connection area, the second bus grid line is continuous at the second edge connection area, and the second bus grid line is discontinuous at other second connection areas.

21. The back-contact solar cell as claimed in claim 14, characterized in that, The first connection area includes a first edge connection area, and only a second edge connection area is provided between it and the second edge main gate; The second main gate bridge is located between the first edge connection area and the second edge main gate, and its end near the first edge connection area extends into the first edge connection area.

22. The back-contact solar cell according to any one of claims 14 to 21, characterized in that, The second grid line also includes a plurality of second sub-collection grid lines arranged at intervals, which are located below the second main grid bridge; the second sub-collection grid lines extend along the first direction; and multiple second sub-collection grid lines are arranged along the first direction.

23. The back-contact solar cell as described in claim 12, characterized in that, The area of ​​at least one second main grid bridge in the back-contact solar cell conforms to the following relationship: In the formula, S γ,j Let S be the area of ​​the j-th second main gate bridge. δ,j S is the area of ​​the second connecting line connected to the j-th second main gate bridge. α,j S represents the area of ​​a single second edge collection gate line electrically connected to the j-th second main gate bridge via the second connection line, μ represents the total number of second edge collection gate lines electrically connected to the j-th second main gate bridge via the second connection line, and S represents the area of ​​a single second edge collection gate line electrically connected to the j-th second main gate bridge via the second connection line. β,j Let λ be the area of ​​a single second sub-collection grid line located below the j-th second main grid bridge, and let λ be the total number of second sub-collection grid lines located below the i-th second main grid bridge.

24. The back-contact solar cell as claimed in claim 22, characterized in that, The value of λ ranges from 2 to 20.

25. The back-contact solar cell as described in claim 22, characterized in that, The second sub-collection grid line is offset from the second edge connection area.

26. The back-contact solar cell as claimed in claim 14, characterized in that, The first grid line includes a first auxiliary collection grid line, which is disposed between the second connecting line and the second edge main grid line. One end of the first auxiliary collection grid line is connected to the second edge main grid line, and the other end is provided with a preset distance from the second connecting line. The first grid line located on the side of the second main grid bridge away from the first auxiliary collection grid line extends to the second edge main grid.

27. A battery assembly, characterized in that, It includes a back-contact solar cell as described in any one of claims 1 to 26, or a slice obtained therefrom.

28. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 27.

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