Back contact solar cell and back contact photovoltaic module

Abstract

The invention discloses a back contact solar cell and a back contact photovoltaic module, the back contact solar cell comprises a silicon substrate, a plurality of groups of bonding pads, a plurality of bus grid lines, a plurality of groups of current collection grid lines and a plurality of connection grid lines, the current transmission path of an edge bonding pad is L1, the L1 comprises an edge current collection grid line and a connection grid line which are connected on the same edge bus grid line, and the edge current collection grid line and the connection grid line are connected on the same edge bus grid line. And an edge bus grid line with a partial length between the edge collector grid line and the connecting grid line; in the first direction, the current transmission path of a middle bonding pad which is closest to the edge bonding pad and has the same polarity as the edge bonding pad is L2, and the L2 comprises a half-length middle current collection grid line and a partial-length middle current collection grid line connected between the middle current collection grid line and the middle bonding pad; and L1 / L2 is greater than or equal to 0.8 and less than or equal to 1.4, so that image blackening of an edge region when the back contact solar cell is subjected to an EL test can be avoided.

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 and a back-contact photovoltaic module. Background Technology

[0002] In back-contact solar cells, both types of grid lines are located on the back side. How to efficiently arrange the grid lines of the two polarities has become a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0003] This application discloses a back-contact solar cell and a back-contact photovoltaic module, which can reduce the abnormal blackening of the EL in back-contact solar cells.

[0004] To achieve the above objectives, in a first aspect, this application discloses a back-contact solar cell, comprising: A silicon substrate having a backlight surface having opposing battery edges along a first direction; Multiple sets of pads are spaced apart on the backlight surface along the first direction, and the polarities of adjacent sets of pads are opposite. The set of pads closest to the edge of each battery is the edge pad, and the remaining sets of pads are the center pads. Each set of pads includes multiple pads spaced apart along a second direction, which intersects with the first direction. Multiple busbars extend along the second direction. Each group of pads is connected to at least one busbar of the same polarity. The busbar connected to the edge pad is the edge busbar, and the busbar connected to the middle pad is the middle busbar. Along the first direction, the edge busbar is disposed between the edge pad and the nearest edge of the battery. Multiple sets of collector gate lines, each set of collector gate lines being connected to pads of the same polarity, the sets of collector gate lines connected to the edge pads being edge collector gate lines, and at least a portion of the edge collector gate lines being connected to the edge bus gate lines; and the sets of collector gate lines connected to the middle pads being middle collector gate lines, and at least a portion of the middle collector gate lines being connected to the middle bus gate lines; and Multiple connecting gate lines, with at least one connecting gate line connecting each edge pad to the nearest edge bus gate line; Wherein, the current transmission path of the edge pad is L1, and L1 includes: the edge collector gate line and the connecting gate line connected to the same edge bus gate line, and a portion of the length of the edge bus gate line between the edge collector gate line and the connecting gate line. Along the first direction, the current transmission path of the middle pad that is closest to the edge pad and has the same polarity as the edge pad is L2. L2 includes: half the length of the middle collector gate line, and a portion of the length of the middle bus gate line connecting the middle collector gate line and the middle pad. The lengths of L1 and L2 satisfy the following relationship: 0.8 ≤ L1 / L2 ≤ 1.4.

[0005] In a possible implementation of the first aspect, along the first direction, the distance between the edge pad and the nearest middle pad is d1, and the distance between the two nearest middle pads is d2, satisfying: d1≤d2.

[0006] In a possible implementation of the first aspect, along the first direction, the distance between the edge pad and the nearest edge busbar is d3, satisfying: 2×d3+d1≤d2.

[0007] In one possible implementation of the first aspect, d2 satisfies: 4.6mm <d2<16.5mm。

[0008] In a possible implementation of the first aspect, along the first direction, the distance between the edge busbar and the nearest central busbar is d4; The d4 satisfies: d4 = d2.

[0009] In one possible implementation of the first aspect, along the first direction, the distance between the edge pad and the nearest edge of the battery is d5, satisfying: 2 mm ≤ d5 ≤ 6 mm.

[0010] In a possible implementation of the first aspect, the connecting gate line is configured as a collector gate line; or, the connecting gate line is configured as part of the bus gate line.

[0011] In a possible implementation of the first aspect, at least one of the edge pads is connected to a plurality of the connecting gate lines.

[0012] Secondly, this application discloses a back-contact photovoltaic module, including a plurality of electrically connected back-contact solar cells, wherein at least one of the back-contact solar cells is the back-contact solar cell described in the first aspect.

[0013] Compared with the prior art, the beneficial effects of this application are as follows: This application increases the distance between the edge pads and the cell edge by placing the edge pads inside the edge busbar, thereby reducing the risk of microcracks at the cell edge during high-temperature soldering. Furthermore, this application optimizes the ratio of the current transmission path lengths of the edge pads and the center pads, enabling the current collection of the edge and center pads to be relatively or as synchronized as possible. This minimizes the difference in current collection losses between the central and edge regions, thus helping to alleviate the blackening of the EL edge of back-contact solar cells and improving the electrical performance of back-contact solar cells.

[0014] Based on the above, this application constructs an edge collector gate line and a connecting gate line connected to the same edge bus line, as well as a portion of the edge bus line between the edge collector gate line and the connecting gate line, as a current transmission path L1 for the edge pad. A half-length central collector gate line and a portion of the central bus line connected between the central collector gate line and the central pad are constructed as a current transmission path L2 for the central pad. Furthermore, L1 and L2 satisfy: 0.8 ≤ L1 / L2 ≤ 1.4.

[0015] In this way, by controlling the ratio between L1 and L2, this application makes the lengths of the current transmission path L1 and L2 relatively close, thereby enabling the current collection of the current transmission paths L1 and L2 to be relatively or as synchronous as possible. This minimizes the difference in current collection loss between the middle and edge regions, which helps to alleviate the blackening of the back contact solar cell EL edge and improve the electrical performance of the back contact solar cell. Attached Figure Description

[0016] 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.

[0017] Figure 1 This is an image of a back-contact solar cell during EL testing in a related technology. Figure 2 This is a schematic diagram of the structure of the back-contact solar cell disclosed in the embodiments of this application; Figure 3 This is a cross-sectional view of a back-contact solar cell disclosed in an embodiment of this application; Figure 4 This is a schematic diagram of L1 and L2 disclosed in the embodiments of this application; Figure 5 This is an image of a back-contact solar cell disclosed in an embodiment of this application during EL testing.

[0018] Explanation of reference numerals in the attached figures: 10. Electrode structure; 1. Bus gate line; 11. Edge bus gate line; 12. Central bus gate line; 2. Collector gate line; 21. Edge collector gate line; 22. Central collector gate line; 4. Pad; 41. Edge pad; 42. Central pad; 5. Connecting gate line; X, First direction; Y, Second direction; Z, Thickness direction of silicon substrate; 100. Back contact solar cell; 20. Silicon substrate; 20a. Light-receiving surface; 20b. Back-lighting surface; 201. Cell edge. Detailed Implementation

[0019] 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.

[0020] In this application, the terms "front" and "back," 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 devices, elements, or components to having a specific orientation, or to be constructed and operated in a specific orientation.

[0021] 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.

[0022] Furthermore, the terms "setup" and "connection" 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.

[0023] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (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, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0024] To fully collect the current generated by the back-contact solar cell during illumination, the edge current collector lines should be placed as close as possible to the cell edge. This expands the current collection range of the edge current collector lines and allows for better collection of photogenerated carriers near the cell edge. To collect the current from the edge current collector lines and maintain a reasonable distance from other central pads, the edge pads are also positioned close to the cell edge.

[0025] However, the inventors discovered that because the area near the edge of the battery is relatively thin, when the edge pads are too close to the edge of the battery, the welding pull generated by the solder strip after it is soldered to the edge pads may cause microcracks at the edge of the battery.

[0026] To avoid the edge pads being too close to the cell edge while still ensuring a sufficient current collection range for the edge current collector grid, the inventors made the following improvements to the back-contact solar cell: The edge pads are positioned sufficiently far from the weak areas at the cell edge; an edge bus grid is added between the edge pads and the cell edge; the edge current collector grid extends to the edge bus grid, and the edge bus grid and edge pads are connected by connecting grid lines. In this way, when the edge current collector grid connects to the edge bus grid, it is close enough to the cell edge, thus providing a larger current collection range. Meanwhile, the edge pads are sufficiently far from the weak areas at the cell edge, thereby reducing the risk of microcracks at the cell edge.

[0027] However, after the above improvements, the back-contact solar cells showed obvious blackening at the edge area during EL (Electroluminescence Test) testing.

[0028] The inventors further discovered that, for example Figure 1 As shown, the reason for the obvious blackening at the edge area of ​​the back contact solar cell is as follows: When edge pads and edge busbars are spaced apart, connecting wires are needed to connect the edge busbars and edge pads to transmit the current collected by the edge collector grid to the edge pads. However, when current is transmitted to the central pad (with the same polarity as the edge pads), the current can be transmitted from the central collector grid to the central busbar and then directly to the central pad. Therefore, under the same polarity, the current transmission path of the edge pads is generally longer than that of the central pads due to the additional connecting wires. These issues may lead to greater current collection losses in the edge region compared to the central region of the back-contact solar cell, causing blackening at the EL edge of the back-contact solar cell, thus affecting the electrical performance and EL appearance yield.

[0029] To address this, this application controls the ratio of the current transmission path L1 of the edge pad to the current transmission path L2 of the middle pad, making the lengths of the current transmission path L1 and L2 relatively close. This allows the current transmission of the edge pad's current transmission path L1 and the middle pad's current transmission path L2 to be relatively or as synchronized as possible, minimizing the difference in current collection loss between the middle and edge regions. This helps alleviate the blackening of the back contact solar cell's EL edge and improves the electrical performance of the back contact solar cell.

[0030] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0031] Please refer to the following: Figure 2 , Figure 3 and Figure 4 This application discloses a back contact solar cell 100 including a silicon substrate 20, multiple sets of pads 4, multiple busbars 1, multiple sets of collector grids 2, and multiple connecting grids 5.

[0032] The silicon substrate 20 has a backlight surface 20b, which has a battery edge 201 disposed opposite to the backlight surface 20b along a first direction X. More specifically, the backlight surface 20b is also referred to as the back side. Along the thickness direction Z of the silicon substrate, the silicon substrate 20 also has a light-receiving surface 20a, i.e., a front side, disposed opposite to the backlight surface 20b.

[0033] Along the first direction X, multiple sets of pads 4 are spaced apart on the backlight surface 20b, and the polarities of adjacent sets of pads 4 are opposite. The set of pads 4 closest to the edge 201 of each battery is the edge pad 41, and the remaining sets of pads 4 are the center pads 42. Each set of pads 4 includes multiple pads 4 spaced apart along the second direction Y, which intersects with the first direction X.

[0034] Each busbar 1 extends along the second direction Y, and each set of pads 4 is connected to at least one busbar 1 of the same polarity. The busbar 1 connected to the edge pad 41 is the edge busbar 11, and the busbar 1 connected to the middle pad 42 is the middle busbar 12. Along the first direction X, the edge busbar 11 is disposed between the edge pad 41 and the nearest battery edge 201.

[0035] Each set of collector grid lines 2 is connected to each set of pads 4 of the same polarity. Each set of collector grid lines 2 connected to the edge pads 41 is an edge collector grid line 21, and at least a portion of the edge collector grid lines 21 are connected to the edge bus grid lines 11. Each set of collector grid lines 2 connected to the middle pads 42 is a middle collector grid line 22, and at least a portion of the middle collector grid lines 22 are connected to the middle bus grid lines 12.

[0036] Each edge pad 41 is connected to at least one connecting gate line 5 between itself and the nearest edge bus gate line 11.

[0037] The current transmission path of the edge pad 41 is L1, which includes: an edge collector gate line 21 and a connecting gate line 5 connected to the same edge bus gate line 11, and a portion of the length of the edge bus gate line 11 between the edge collector gate line 21 and the connecting gate line 5.

[0038] Along the first direction X, the current transmission path of the middle pad 42, which is closest to the edge pad 41 and has the same polarity as the edge pad 41, is L2. L2 includes: a middle collector gate line 22 of half length, and a middle bus gate line 12 of a portion length connecting the middle collector gate line 22 and the middle pad 42.

[0039] The lengths of L1 and L2 satisfy the following relationship: 0.8≤L1 / L2≤1.4.

[0040] For example, L1 / L2 can be 1.4, 1.3, 1.2, 1.1, 1, 0.9, 0.8, etc.

[0041] In this application, the edge collector grid line 21 in L1 and the middle collector grid line 22 in L2 are preferably collector grid lines 2 arranged on the same straight line along the first direction X.

[0042] Furthermore, to facilitate comparison of the lengths of L1 and L2, when calculating the current transmission path L1 of the edge pad 41, the selected edge collector gate line 21 can be the first edge collector gate line 21 in this group of edge collector gate lines 21 along the second direction Y. Similarly, when calculating the current transmission path L2 of the middle pad 42, the selected middle collector gate line 22 is the first middle collector gate line 22 in this group of middle collector gate lines 22 along the second direction Y.

[0043] More specifically, since the center of the central collector gate 22 intersects the central bus gate 12 along the first direction X, the current transmission path L2 of the central pad 42 includes half the length of the central collector gate 22. Furthermore, since each central bus gate 12 is intersecting and connected to each group of central pads 42, the current of the central collector gate 22 is directly transmitted to the central pad 42 through the central bus gate 12, without any intermediate transmission medium between the central bus gate 12 and the central pad 42. Therefore, the current transmission path L2 of the central pad 42 also includes a portion of the length of the central bus gate 12 between the central collector gate 22 and the central pad 42.

[0044] The beneficial effects of the back contact solar cell 100 of this application will be described in detail below.

[0045] This application increases the distance between the edge pad 41 and the cell edge 201 by placing the edge pad 41 inside the edge busbar 11, thereby reducing the risk of microcracks in the cell edge 201. Furthermore, this application optimizes the ratio of the current transmission path lengths of the edge pad 41 and the middle pad 42, enabling the currents of the edge pad 41 and the middle pad 42 to be relatively or as synchronized as possible. This minimizes the difference in current collection losses between the middle and edge regions, thus helping to alleviate the blackening of the edge of the back contact solar cell 100EL.

[0046] In this application, the edge busbar 11 is disposed between the edge pad 41 and the nearest battery edge 201. In other words, the edge pad 41 is disposed inside the edge busbar 11, and is farther from the battery edge 201 than the edge busbar 11. After the solder ribbon is soldered to the edge pad 41, the solder joint can be farther away from the weak area of ​​the battery edge 201, which helps to reduce the risk of microcracks in the battery edge 201. Furthermore, at least a portion of the edge current collector 21 is connected to the edge busbar 11 that is closer to the battery edge 201, so that the edge current collector 21 can be as close to the battery edge 201 as possible, which helps to expand the current collection range of the edge current collector 21, thereby helping to improve the conversion efficiency of the back contact solar cell 100.

[0047] Based on the above, this application further considers that when the edge pad 41 and the edge busbar 11 are spaced apart, the edge busbar 11 and the edge pad 41 need to be connected by the connecting grid line 5 to collect the current on the edge busbar 11 and the edge collector grid line 21 connected to the edge busbar 11 to the edge pad 41. However, when the middle pad 42, which is closest to the edge pad 41 and has the same polarity as the edge pad 41, collects current along the first direction X, the current can be transported from the middle collector grid line 22 to the middle busbar 12, and then directly to the middle pad 42 for direct current collection. It is evident that the current transmission path of the edge pad 41 is relatively long. This may result in a large difference between the current collection in the edge region and the current loss in the middle region of the back contact solar cell 100, causing blackening of the EL edge of the back contact solar cell 100, affecting the electrical performance and EL appearance yield of the back contact solar cell 100.

[0048] Based on the above analysis, this application constructs the edge collector gate 21 and the connecting gate 5 connected to the same edge bus gate 11, as well as the portion of the edge bus gate 11 between the edge collector gate 21 and the connecting gate 5, as the current transmission path L1 of the edge pad 41. The middle collector gate 22 (half its length) and the portion of the middle bus gate 12 connected between the middle collector gate 22 and the middle pad 42 are constructed as the current transmission path L2 of the middle pad 42. Furthermore, L1 and L2 satisfy: 0.8 ≤ L1 / L2 ≤ 1.4.

[0049] In other words, this application controls the ratio between L1 and L2 to avoid the current transmission path L1 of the edge pad 41 being too long relative to the current transmission path L2 of the middle pad 42, making the lengths of the current transmission path L1 and L2 relatively close. This ensures that the current collection of the current transmission paths L1 and L2 can be relatively or as synchronized as possible, minimizing the difference in current collection loss between the middle and edge regions. This helps alleviate the blackening of the EL edge of the back contact solar cell 100. Figure 5 In the EL test image shown, compared to Figure 1 , Figure 5 The blackening at the edge of the back contact solar cell 100 is significantly improved, which is beneficial to improving the electrical performance of the back contact solar cell 100 and also helps to improve the EL appearance yield of the back contact solar cell 100.

[0050] The electrode structure 10 of this application will now be described in detail. Specifically, the electrode structure 10 refers to a structure composed of a bus gate, a collector gate, pads, and connecting gates.

[0051] Please see Figure 4 Along the first direction X, the distance between the edge pad 41 and the nearest middle pad 42 is d1, and the distance between the two nearest middle pads 42 is d2, satisfying: d1≤d2.

[0052] Specifically, d1 is the distance between the geometric center of the edge pad 41 and the geometric center of the middle pad 42 along the first direction X. d2 is the distance between the geometric centers of two adjacent middle pads 42 along the first direction X.

[0053] In one example, when d1 = d2, the pads 4 are equidistantly arranged along the first direction X on the back contact solar cell 100, which helps to improve the overall EL appearance of the electrode structure 10. Furthermore, the equidistant arrangement of the pads 4 also allows the solder ribbons to be welded equidistantly onto the back contact solar cell 100, thereby ensuring a uniform distribution of stress on the back contact solar cell 100 after soldering, and preventing microcracks in the solar cell due to localized stress concentration.

[0054] In another example, when d1 < d2, that is, the spacing between the edge pad 41 and the middle pad 42 is relatively narrow. It is understandable that since the collector grid line 2 extends as far as possible between adjacent pads 4, the length of the collector grid line 2 is positively correlated with the spacing between adjacent pads 4. Therefore, when the spacing between the edge pad 41 and the middle pad 42 is relatively narrow, the length of the edge collector grid line 21 can also be correspondingly shorter. Since L1 has more connecting grid lines 5 than L2, a shorter edge collector grid line 21 helps to reduce the absolute difference in length between L1 and L2, thereby enabling the current collection of L1 and L2 to be relatively or as synchronized as possible, minimizing the difference in current collection loss between the middle and edge regions, thus helping to alleviate the blackening of the EL edge of the back contact solar cell 100.

[0055] Please see Figure 4 In this application, along the first direction X, the distance between the edge pad 41 and the nearest edge busbar 11 is d3. Optionally, d3 satisfies: 2×d3+d1≤d2.

[0056] Specifically, d3 is the distance between the geometric center of the edge pad 41 and the geometric center of the edge busbar 11 along the first direction X.

[0057] It is understandable that when the central pad 42 and the edge pad 41 are aligned along the first direction X, the length of the edge busbar 11 in L1 is relatively consistent with the length of the central busbar 12 in L2. In this case, the difference between L1 and L2 is mainly the difference between 2×d3+d1 and d2. It should be noted that when d2 is less than 2×d3+d1, L1 tends to be too long relative to the length of L2, resulting in an excessively long current transmission path at the battery edge 201, which can easily lead to blackening of the EL (electro-optical circuit) near the battery edge 201.

[0058] In other words, when d2≥2×d3+d1, the length of L1 is closer to the length of L2, which makes the current collection of L1 and L2 relatively synchronized, so that the difference in current collection loss between the middle region and the edge region is as small as possible. This helps to reduce the blackening of EL near the edge 201 of the battery and improve the electrical performance of the back contact solar cell 100.

[0059] Please see Figure 4 In this application, along the first direction X, the distance between the edge busbar 11 and the nearest central busbar 12 is d4. Optionally, d4 satisfies: d4=d2.

[0060] Specifically, d4 is the distance between the center of the edge busbar 11 along the first direction X and the center of the middle busbar 12 along the first direction X.

[0061] In other words, the equidistant arrangement of each busbar 1 not only makes the electrode structure 10 more aesthetically pleasing, but also ensures that half the length of the edge collector line 21 and the middle collector line 22 are roughly equal. This makes the current collection in the edge and middle regions more synchronized, minimizing the difference in current collection loss between the middle and edge regions, which helps reduce EL blackening.

[0062] Alternatively, the above d2 satisfies: 4.6mm <d2<16.5mm。

[0063] For example, the range of d2 can be 4.6mm-5.6mm, 5.6mm-6.6mm, 6.6mm-7.6mm, 7.6mm-8.6mm, 8.6mm-9.6mm, 9.6mm-10.6mm, 10.6mm-11.6mm, 11.6mm-12.6mm, 12.6mm-13.6mm, 13.6mm-14.6mm, 14.6mm-15.6mm, 15.6mm-16.5mm, etc. For example, d2 can be 4.7mm, 5mm, 5.6mm, 6mm, 6.6mm, 7mm, 7.6mm, 8mm, 8.6mm, 9mm, 9.6mm, 10mm, 10.6mm, 11mm, 11.6mm, 12mm, 12.6mm, 13mm, 13.6mm, 14mm, 14.6mm, 15mm, 15.6mm, 16mm, or 16.4mm, etc.

[0064] Understandably, the central collector grid line 22 will extend as far as possible between the two sets of adjacent central pads 42. Therefore, the length of the central collector grid line 22 is positively correlated with d2. Preferably, d2 is less than 16.5 mm, which results in a shorter central collector grid line 22, which helps to shorten the current transmission path and thus reduce the transmission loss of the central collector grid line 22. Furthermore, d2 is preferably greater than 4.6 mm to ensure a moderate spacing between the two sets of adjacent central pads 42, preventing stress concentration caused by overly dense solder joints.

[0065] Please see Figure 4 In this application, the distance between the edge pad 41 and the nearest battery edge 201 is d5. Optionally, d5 satisfies: 2mm ≤ d5 ≤ 6mm.

[0066] Specifically, d5 is the distance between the geometric center of the edge pad 41 and the geometric center of the battery edge 201 in the first direction.

[0067] For example, the range of d5 can be 2mm-3mm, 3mm-4mm, 4mm-5mm, 5mm-6mm, etc. d5 can be 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, or 6mm, etc.

[0068] Preferably, d5 is greater than or equal to 2 mm, ensuring a sufficiently large distance between the edge pad 41 and the cell edge 201, thereby reducing the risk of microcracks in the cell edge 201. Furthermore, d5 should not be too large; preferably, it is less than or equal to 6 mm. Since the distance between the edge busbar 11 and the cell edge 201 is within 2 mm, when the distance between the edge pad 41 and the cell edge 201 does not exceed 6 mm, the distance between the edge pad 41 and the edge busbar 11 remains relatively narrow. This helps to shorten the length of the connecting grid line 5, thereby reducing the length difference between L1 and L2 and mitigating the degree of EL blackening in the back contact solar cell edge area.

[0069] Please see Figure 2 as well as Figure 4 In some embodiments, at least one edge pad 41 is connected to a plurality of connection gates 5 between the edge bus gate 11 and the edge pad pad 41.

[0070] Understandably, multiple connecting gate lines 5 can shunt the current collected by the edge bus gate lines 11 to reduce the current intensity of the connecting gate lines 5, thereby reducing the transmission loss of the connecting gate lines 5.

[0071] Of course, there may also be only one connecting gate line 5 between the edge pad 41 and the edge bus gate line 11.

[0072] It should be noted that when multiple connecting gate lines 5 are connected between the edge pad 41 and the edge bus gate line 11, the length of one of the connecting gate lines 5 only needs to be included when calculating the length of L1. Furthermore, considering that the current will spontaneously travel along the path with the lowest resistivity, the connecting gate line 5 with the lowest resistivity is selected when calculating the length of L1.

[0073] In some embodiments, the connecting gate line 5 is configured as a collector gate line, or the connecting gate line 5 is configured as part of the bus gate line 1.

[0074] In other words, the connecting grid line 5 can be printed together with the current collector grid line 2 using a burn-through paste, thereby also serving to collect current and expanding the current collection area. Alternatively, the connecting grid line 5 can be printed together with the bus grid line using a non-burn-through paste, which helps to reduce damage to the passivation film layer and thus reduce the recombination loss at the connecting grid line 5.

[0075] This application also discloses a photovoltaic module, including the back-contact solar cell in any of the above embodiments.

[0076] For example, a photovoltaic module may consist of one or more back-contact solar cells. Multiple back-contact solar cells are connected in series, in parallel, or in a combination of series and parallel by solder strips.

[0077] The foregoing has provided a detailed description of the back-contact solar cell and back-contact photovoltaic module disclosed in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the back-contact solar cell and back-contact photovoltaic module and their core ideas. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A back-contact solar cell, characterized in that, include: A silicon substrate having a backlight surface having opposing battery edges along a first direction; Multiple sets of pads are spaced apart on the backlight surface along the first direction, and the polarities of adjacent sets of pads are opposite. The set of pads closest to the edge of each battery is the edge pad, and the remaining sets of pads are the center pads. Each set of pads includes multiple pads spaced apart along a second direction, which intersects with the first direction. Multiple busbars extend along the second direction. Each group of pads is connected to at least one busbar of the same polarity. The busbar connected to the edge pad is the edge busbar, and the busbar connected to the middle pad is the middle busbar. Along the first direction, the edge busbar is disposed between the edge pad and the nearest edge of the battery. Multiple sets of collector gate lines, each set of collector gate lines being connected to pads of the same polarity, the sets of collector gate lines connected to the edge pads being edge collector gate lines, and at least a portion of the edge collector gate lines being connected to the edge bus gate lines; and the sets of collector gate lines connected to the middle pads being middle collector gate lines, and at least a portion of the middle collector gate lines being connected to the middle bus gate lines; and Multiple connecting gate lines, with at least one connecting gate line connecting each edge pad to the nearest edge bus gate line; Wherein, the current transmission path of the edge pad is L1, and L1 includes: the edge collector gate line and the connecting gate line connected to the same edge bus gate line, and a portion of the length of the edge bus gate line between the edge collector gate line and the connecting gate line. Along the first direction, the current transmission path of the middle pad that is closest to the edge pad and has the same polarity as the edge pad is L2. L2 includes: half the length of the middle collector gate line, and a portion of the length of the middle bus gate line connecting the middle collector gate line and the middle pad. The lengths of L1 and L2 satisfy the following relationship: 0.8 ≤ L1 / L2 ≤ 1.

4.

2. The back-contact solar cell according to claim 1, characterized in that, Along the first direction, the distance between the edge pad and the nearest middle pad is d1, and the distance between the two nearest middle pads is d2, satisfying: d1≤d2.

3. The back-contact solar cell according to claim 2, characterized in that, Along the first direction, the distance between the edge pad and the nearest edge busbar is d3, which satisfies: 2×d3+d1≤d2.

4. The back-contact solar cell according to claim 2, characterized in that, The d2 satisfies: 3mm <d2<13mm。 5. The back-contact solar cell according to claim 2, characterized in that, Along the first direction, the distance between the edge busbar and the nearest central busbar is d4; The d4 satisfies: d4 = d2.

6. The back-contact solar cell according to any one of claims 1-5, characterized in that, Along the first direction, the distance between the edge pad and the nearest edge of the battery is d5, which satisfies: 2 mm ≤ d5 ≤ 6 mm.

7. The back-contact solar cell according to any one of claims 1-5, characterized in that, The connecting grid line is configured as a collector grid line; or, the connecting grid line is configured as part of the bus grid line.

8. The back-contact solar cell according to any one of claims 1-5, characterized in that, At least one of the edge pads is connected to a plurality of the connection gate lines between it and the edge bus gate line.

9. A back-contact photovoltaic module, characterized in that, It includes a plurality of electrically connected back-contact solar cells, wherein at least one of the back-contact solar cells is the back-contact solar cell according to any one of claims 1 to 8.

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