Back contact electrode structure, back contact solar cell and photovoltaic module

Abstract

The invention discloses a back contact electrode structure, a back contact solar cell and a photovoltaic module, and belongs to the technical field of solar cells. The electrode structure comprises current collection electrodes, current collection electrodes, current collection points and current collection areas, the current collection electrodes extend in the first direction, and the current collection electrodes with different polarities are alternately designed at intervals in the second direction; the bus electrodes are distributed on the two sides of the battery substrate in the second direction, the bus electrodes with the same polarity are distributed on one side of the edge of the battery substrate, the bus electrodes with the other polarity are distributed on the other side of the edge of the battery substrate, and the bus electrodes with different polarities are distributed in an array mode in the first direction and are coupled with the part, extending in the first direction, of the collector electrodes with the same polarity; the collector electrodes at least partially extending in the first direction have a segmented design, and the length of the collector electrodes on the two sides of the battery substrate in the first direction is W1lt; and the other collector electrodes are W2 in length.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cells, and in particular relates to a back contact electrode structure, a back contact solar cell sheet and a photovoltaic module. Background Art

[0002] Back-contact solar cells are a type of cell structure where the positive and negative electrodes are located on the non-light-receiving side of the cell. Since there is no grid line blocking the front side of this type of cell, it effectively increases the collection of solar energy and improves the short-circuit current of the cell. In related technologies, in order to achieve component interconnection, back-contact cells usually use two electrode designs: with a main grid and without a main grid. Among them, the design of a cell with a main grid is as follows: Figure 1 The design usually adopts the main grid busbar and pad welding method. This method reduces the carrier transfer resistance of the main grid. The main grid design is usually wide, resulting in a higher silver paste consumption, which increases the cost. In addition, this design has a large current transfer resistance in the main grid area and a high efficiency loss. In addition, the excessively wide main grid contacts the welding ribbon, causing serious warping problems for the battery cell and posing a reliability risk.

[0003] Another is like Figure 2 The conventional busbar-free welding method requires printing an insulating array on the opposite-sex electrode. The height of this type of array is usually 20-30μm. A thicker solder paste array must be printed on the same-sex electrode to achieve solder ribbon interconnection. A silver electrode substrate is also required at the bottom of the solder paste. Low-temperature lamination must be selected for component lamination, which leads to complex component manufacturing process and increased reliability risk. Moreover, large-area contact between high-density solder paste and solder ribbon will also cause serious battery warping, leading to component reliability risks. Summary of the invention

[0004] 1. Problem to be solved In view of the technical problems in the prior art, the purpose of the present invention is to propose a back contact electrode structure, a back contact solar cell and a photovoltaic module to reduce the risk of module failure caused by battery welding warping and improve the efficiency and reliability of the back contact solar cell.

[0005] 2. Technical solution In order to solve the above problems, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a back contact electrode structure, which includes a collector electrode, a bus electrode, a bus point and a bus region, wherein: The collector electrodes extend along a first direction, and the collector electrodes of different polarities are alternately arranged along a second direction; The bus electrodes are distributed on both sides of the battery substrate along the second direction, the bus electrodes of the same polarity are distributed on one side of the edge of the battery substrate, and the bus electrodes of the other polarity are distributed on the other side, and the bus electrodes of different polarities are distributed in an array along the first direction and are coupled with the collector electrodes of the same polarity extending along the first direction; Edge collector electrodes extending along the second direction are designed at both side edges of the battery substrate along the second direction, and are coupled with the collector electrodes extending along the first direction; Designing edge bus points and edge bus electrodes at the edges of both sides of the battery substrate along the second direction; The confluence points are distributed in an array along the first direction and the second direction, and in the array area extending along the second direction, there are only confluence points of the same polarity; the area where the confluence points are coupled with the collector electrodes is designed as a confluence area for welding of welding strips; At least part of the collector electrodes extending along the first direction have a segmented design, and along the first direction, the length of the collector electrodes on both sides of the battery substrate W1 is less than the length of other collector electrodes W2, and the other collector electrodes include adjacent opposite-sex collector electrodes and same-sex collector electrodes away from the edge of the battery substrate. Preferably, the length of the collector electrodes on both sides is ≥10mm, and the length of other collector electrodes is ≥15mm, and <20mm.

[0006] In the above structural design, the collecting electrodes of the same polarity extend to the edge of the battery substrate, while the collecting electrodes of the other polarity do not extend to the edge of the battery substrate. This can facilitate the collection of more carriers on the collecting electrodes, which not only effectively avoids the short circuit problem, but also maximizes the space utilization of the battery substrate.

[0007] According to any embodiment of the first aspect of the present invention, the busbar in the busbar area along the first direction of the battery substrate is hollowed out, the collecting electrode passes through the center of the busbar and is coupled with the vertical midline of the center of the busbar along the second direction.

[0008] Firstly, the hollow design of the busbar can not only enhance the welding tension between the busbar and the welding strip, effectively improving the reliability of the battery cell, but also optimize the carrier distribution and reduce welding stress concentration; in addition, the above hollow design can also reduce the use of corresponding materials, thereby reducing the production cost of the battery.

[0009] Secondly, the above-mentioned hollow design and the collecting electrode passing through the center point of the confluence point reduce the contact area between the confluence point and the battery substrate, thereby reducing the corrosion of the metal to the battery substrate, which is beneficial to the performance assurance of the battery substrate; and shortening the transmission path of the carriers, which is beneficial to the transmission loss of the carriers collected by the collecting electrode to the welding strip, so that the solar cell has a larger open circuit voltage.

[0010] Finally, combined with the current data analysis, it is known that the above design has almost no effect on the current stability and efficiency of the solar cell of the present invention.

[0011] According to any embodiment of the first aspect of the present invention, the length of the busbar along the first direction is ≥0.6mm and ≤2mm. Preferably, the length is 0.6mm, 0.7mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, 1.6mm, 1.8mm, 1.9mm, or 2mm. The above structure can further improve the contact area between the busbar and the battery substrate, thereby reducing the contact resistance between the two and reducing transmission losses.

[0012] The total area formed by the outer contour of the confluence point of the hollow design is ≥ 0.01mm 2 , and ≤1mm 2 , preferably, the total area is 0.01mm 2 , 0.02mm 2 , 0.03mm 2 , 0.04mm 2 , 0.05mm 2 , 0.06mm 2 , 0.07mm 2 、0.08mm 2 、0.09mm 2 , 0.1mm 2 , 0.15mm 2 , 0.2mm 2 , 0.25mm 2 , 0.35mm 2 , 0.45mm 2 , 0.55mm 2 , 0.65mm 2 , 0.7mm 2 , .8mm 2 , 0.9mm 2 , 1mm 2 .

[0013] According to any embodiment of the first aspect of the present invention, the area of ​​the non-hollowed-out portion of the hollowed-out design accounts for ≥5% and <100% of the total area of ​​the confluence point. Preferably, the proportion is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, 101%, 102%, 103%, 104%, 105%, 106%, 107%, 108%, 109%, 110%, 111%, 112%, 113%, 114%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%.

[0014] In this case, it is beneficial to increase the contact area between the busbar and the battery substrate, reduce transmission loss, and at the same time, improve the connection stability between the busbar and the battery substrate, and enhance the reliability of the solar cell structure.

[0015] According to any embodiment of the first aspect of the present invention, the collecting electrode is disconnected along the second direction in the non-isotropic bus region, and the disconnection length is D1; ​​along the second direction, both sides of the battery substrate are retracted from the non-isotropic collecting electrodes extending along the second direction, and the retracted length is D2, and D2≤D1 / 2; and / or, the sum of the disconnection lengths of the collecting electrodes in the same row and the same polarity is ≥0.05 and ≤0.2 to the length L0 of the battery substrate along the first direction, and preferably, the ratio is 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2.

[0016] According to any embodiment of the first aspect of the present invention, the length of the edge collector electrode extending along the second direction on both sides of the battery substrate is ≤ L1*100% of the length of the battery substrate along the second direction, and ≥ L1*90% of the length of the battery substrate along the second direction. Preferably, the edge collector electrode length = L1*91% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*92% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*93% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*94% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*95% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*96% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*97% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*98% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*99% of the length of the battery substrate along the second direction, and the edge collector electrode length = L1*100% of the length of the battery substrate along the second direction.

[0017] According to any embodiment of the first aspect of the present invention, the bus electrodes on both sides of the second direction of the battery substrate are arranged in an array along the second direction, and have the same polarity on one side and another polarity on the other side; the length L2 of the bus electrodes on both sides along the first direction is ≥2mm and ≤4mm, preferably, L2 is 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3.0mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm; and / or the total area of ​​the bus electrodes is ≥0.5mm 2 , and ≤2mm 2 , preferably, the total area is 0.5mm 2 , 0.6mm 2 , 0.7mm 2 , 0.8mm 2 , 0.9mm 2 , 1.0mm 2 , 1.1mm 2 , 1.2mm 2 , 1.3mm 2 , 1.4mm 2 , 1.5mm 2 , 1.6mm 2 , 1.7mm 2 , 1.8mm 2 , 1.9mm 2 , 2mm 2 .

[0018] According to any embodiment of the first aspect of the present invention, the edge bus points on both sides of the battery substrate along the first direction are coupled with the bus electrodes extending along the first direction, and are coupled with part of the collector electrodes along the first direction; the edge bus points are circular solid designs, with a diameter of ≥0.5mm and ≤1mm; the number of collector electrodes coupled with the edge bus points is ≥1 and ≤3. Preferably, the diameter is 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm; the number of collector electrodes coupled with the edge bus points is 1, 2, or 3.

[0019] According to any embodiment of the first aspect of the present invention, the collecting electrode at the edge of the battery substrate along the first direction has a bending design, and the bending angle is ≥90° and <180°. Preferably, the bending angle a is 90°, 95°, 100°, 105°, 110°, 115°, 120°, 125°, 130°, 135°, 140°, 150°, 155°, 160°, 165°, 170°, 175°, or 179°.

[0020] According to any embodiment of the first aspect of the present invention, collecting electrodes of different polarities use different conductive materials; bus electrodes and bus points of different polarities all use the same conductive material; and / or: bus points of different polarities use the same conductive material as the collecting electrodes coupled thereto, and circular edge bus points and bus electrodes of different polarities all use the same conductive material.

[0021] The above-mentioned conductive materials are all commercially available products, such as copper, aluminum, tungsten, titanium and the like.

[0022] According to any embodiment of the first aspect of the present invention, at least one bus point is simultaneously coupled with the collecting electrode along the second direction and the bus electrode extending along the second direction, and the number of coupling points is ≥1 and ≤10. Preferably, the number of coupling points is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0023] According to any embodiment of the first aspect of the present invention, a bus electrode gradually changing along the second direction is coupled to at least one collecting electrode; the gradual change of the bus electrode always extends from the edge of the battery substrate to the inside of the battery, and the minimum value of the gradual change of the width along the first direction is ≥30μm and ≤80μm, preferably 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm, 51μm, 52μm, 53μm, 54μm, 55μm, 56μm, 57μm, 58μm, The maximum value of the width gradient along the first direction is ≥150μm and ≤300μm; preferably, it is 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, 210μm, 220μm, 230μm, 240μm, 250μm, 260μm, 270μm, 280μm, 290μm, 295μm, 300μm.

[0024] According to any embodiment of the first aspect of the present invention, at the edge of the battery substrate, the bus electrode is coupled with the like-polarity collecting electrode, and the end protrudes from the collecting electrode along the second direction, and the protrusion length H is greater than 120μm and less than or equal to 150μm. Preferably, the protrusion length H is 121μm, 125μm, 128μm, 130μm, 132μm, 135μm, 138μm, 140μm, 142μm, 145μm, 148μm, or 150μm.

[0025] According to any embodiment of the first aspect of the present invention, the area formed by the disconnection of the anisotropic collector electrode along the second direction is the confluence area, and the length D1 of the collector electrode disconnection is ≥ 0.6 mm and ≤ 1.5 mm. Preferably, the length D1 is 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm. Correspondingly, the retracted length D2 is 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm.

[0026] According to any embodiment of the first aspect of the present invention, any bus electrodes extending along the second direction have the same length or the number of bus electrodes coupled to the collecting electrodes is the same.

[0027] According to any embodiment of the first aspect of the present invention, an insulating array covers the opposite-sex collecting electrodes in the bus region.

[0028] A second aspect of the present invention provides a back contact electrode structure, which includes a collector electrode, a bus electrode, a bus point and a bus region, wherein: The collector electrodes extend along a first direction, and the collector electrodes of different polarities are alternately arranged along a second direction; The bus electrodes are distributed on both sides of the battery substrate along the second direction, the bus electrodes of the same polarity are distributed on one side of the edge of the battery substrate, and the bus electrodes of the other polarity are distributed on the other side, and the bus electrodes of different polarities are distributed in an array along the first direction and are coupled with the collector electrodes of the same polarity extending along the first direction; Edge collector electrodes extending along the second direction are designed at both side edges of the battery substrate along the second direction, and are coupled with the collector electrodes extending along the first direction; Designing edge bus points and edge bus electrodes at the edges of both sides of the battery substrate along the second direction; The confluence points are distributed in an array along the first direction and the second direction, and in the array area extending along the second direction, there are only confluence points of the same polarity; the area where the confluence points are coupled with the collector electrodes is designed as a confluence area for welding of welding strips; Any extension line of the center of the edge bus electrode on both sides of the battery substrate along the first direction is horizontal and does not intersect, and the horizontal spacing L3 of the center lines extending from the two nearest opposite edge bus electrodes along the first direction is ≥0.1mm and ≤3mm. Preferably, L3 is 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.8mm, 2.9mm, 3mm.

[0029] The above-mentioned collector electrodes are distributed on the battery substrate at equal intervals along the second direction. On both sides of the battery substrate along the first direction, in order to improve the extraction efficiency of carriers, the collector electrodes, edge collector electrodes and edge bus electrodes of the same polarity are coupled with each other to extract these carriers. However, when the edge bus electrodes are on the same plane, their edge bus points will cross two collector electrodes of different polarities. This design is not only easy to cause short circuits, but also form poor contact areas. At the same time, the effective contact area between the edge bus points and the welding strip is small, which increases the transmission loss. Therefore, the extension lines of the centers of the first edge bus electrodes and the second edge bus electrodes on both sides of the battery substrate along the first direction of the present invention are horizontal and do not intersect. The edge bus points are connected to the collector electrodes of the same polarity, and the effective contact area with the welding strip is increased, thereby improving the welding strength.

[0030] According to any embodiment of the second aspect of the present invention, the confluence point in the confluence area along the first direction of the battery substrate is a hollow design, and the projection of the confluence point is a hollow design such as a rhombus or ellipse, preferably a rhombus, and the collecting electrode passes through the center point of the confluence point and is coupled with the vertical midline of the center of the confluence point along the second direction.

[0031] Firstly, the hollow design of the busbar can not only enhance the welding tension between the busbar and the welding strip, effectively improving the reliability of the battery cell, but also optimize the carrier distribution and reduce welding stress concentration; in addition, the above hollow design can also reduce the use of corresponding materials, thereby reducing the production cost of the battery.

[0032] Secondly, the above-mentioned hollow design and the collecting electrode passing through the center point of the confluence point reduce the contact area between the confluence point and the battery substrate, thereby reducing the corrosion of the metal to the battery substrate, which is beneficial to the performance assurance of the battery substrate; and shortening the transmission path of the carriers, which is beneficial to the transmission loss of the carriers collected by the collecting electrode to the welding strip, so that the solar cell has a larger open circuit voltage.

[0033] Finally, combined with the current data analysis, it is known that the above design has almost no effect on the current stability and efficiency of the solar cell of the present invention.

[0034] According to any embodiment of the second aspect of the present invention, the length of the busbar along the first direction is ≥0.6mm and ≤2mm. Preferably, the length is 0.6mm, 0.7mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, 1.6mm, 1.8mm, 1.9mm, or 2mm. The above structure can further improve the contact area between the busbar and the battery substrate, thereby reducing the contact resistance between the two and reducing transmission losses.

[0035] The total area formed by the outer contour of the confluence point of the hollow design is ≥ 0.01mm 2 , and ≤1mm2 , preferably, the total area is 0.01mm 2 , 0.02mm 2 , 0.03mm 2 , 0.04mm 2 , 0.05mm 2 , 0.06mm 2 , 0.07mm 2 、0.08mm 2 、0.09mm 2 , 0.1mm 2 , 0.15mm 2 , 0.2mm 2 , 0.25mm 2 , 0.35mm 2 , 0.45mm 2 , 0.55mm 2 、0.65mm 2 , 0.7mm 2 , 0.8mm 2 , 0.9mm 2 , 1mm 2 .

[0036] According to any embodiment of the second aspect of the present invention, the area of ​​the non-hollowed-out portion of the hollowed-out design accounts for ≥5% of the total area of ​​the confluence point and <100%. Preferably, the proportion is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, 101%, 102%, 103%, 104%, 105%, 106%, 107%, 108%, 109%, 110%, 111%, 112%, 113%, 114%, 1 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%.

[0037] According to any embodiment of the second aspect of the present invention, the collector electrode is disconnected along the second direction in the non-homogeneous confluence region, and the disconnection length is D1; ​​along the second direction, the distance between the collector electrode extending in the non-homogeneous direction and the collector electrode on both sides of the battery substrate is retracted, and the retracted length is D2, and D2≤D1 / 2; and / or, the sum of the disconnection lengths of the collector electrodes in the same row and the same polarity and the length L0 of the battery substrate along the first direction are ≥0.05 and ≤0.2. Preferably, the ratio is 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2.

[0038] According to any embodiment of the second aspect of the present invention, the length of the edge collector electrode extending along the second direction on both sides of the battery substrate is ≤ L1*100% of the length of the battery substrate along the second direction, and ≥ L1*90% of the length of the battery substrate along the second direction. Preferably, the edge collector electrode length = L1*91% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*92% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*93% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*94% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*95% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*96% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*97% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*98% of the length of the battery substrate along the second direction, the edge collector electrode length = L1*99% of the length of the battery substrate along the second direction, and the edge collector electrode length = L1*100% of the length of the battery substrate along the second direction.

[0039] According to any embodiment of the second aspect of the present invention, the bus electrodes on both sides of the second direction of the battery substrate are arranged in an array along the second direction, and have the same polarity on one side and another polarity on the other side; the length L2 of the bus electrodes on both sides along the first direction is ≥2mm and ≤4mm, preferably, L2 is 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3.0mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm; and / or the total area of ​​the bus electrodes is ≥0.5mm 2 , and ≤2mm 2 , preferably, the total area is 0.5mm 2 , 0.6mm 2 , 0.7mm 2 , 0.8mm2 , 0.9mm 2 , 1.0mm 2 , 1.1mm 2 , 1.2mm 2 , 1.3mm 2 , 1.4mm 2 , 1.5mm 2 , 1.6mm 2 , 1.7mm 2 , 1.8mm 2 , 1.9mm 2 , 2mm 2 .

[0040] According to any embodiment of the second aspect of the present invention, the edge bus points on both sides of the battery substrate along the first direction are coupled with the bus electrodes extending along the first direction, and are coupled with part of the collector electrodes along the first direction; the edge bus points are circular solid designs, with a diameter of ≥0.5mm and ≤1mm; the number of collector electrodes coupled with the edge bus points is ≥1 and ≤3. Preferably, the diameter is 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm; the number of collector electrodes coupled with the edge bus points is 1, 2, or 3.

[0041] According to any embodiment of the second aspect of the present invention, the collector electrode at the edge of the battery substrate along the first direction has a bending design, and the bending angle is ≥90° and <180°. Preferably, the bending angle a is 90°, 95°, 100°, 105°, 110°, 115°, 120°, 125°, 130°, 135°, 140°, 150°, 155°, 160°, 165°, 170°, 175°, 179°.

[0042] According to any embodiment of the second aspect of the present invention, collecting electrodes of different polarities use different conductive materials; bus electrodes and bus points of different polarities all use the same conductive material; and / or: bus points of different polarities use the same conductive material as the collecting electrodes coupled thereto, and circular edge bus points and bus electrodes of different polarities all use the same conductive material.

[0043] According to any embodiment of the second aspect of the present invention, at least one bus point is coupled with the collector electrode along the second direction and the bus electrode extending along the second direction at the same time, and the number of coupling points is ≥ 1 and ≤ 10. Preferably, the number of coupling points is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0044] According to any embodiment of the second aspect of the present invention, a bus electrode gradually changing along the second direction is coupled to at least one collecting electrode; the gradual change of the bus electrode always extends from the edge of the battery substrate to the inside of the battery, and the minimum value of the gradual change of the width along the first direction is ≥30μm and ≤80μm, preferably, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm, 51μm, 52μm, 53μm, 54μm, 55μm, 56μm, 57μm, 58μm, The maximum value of the width gradient along the first direction is ≥150μm and ≤300μm; preferably, it is 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, 210μm, 220μm, 230μm, 240μm, 250μm, 260μm, 270μm, 280μm, 290μm, 295μm and 300μm.

[0045] According to any embodiment of the second aspect of the present invention, at the edge of the battery substrate, the bus electrode is coupled with the like-sex collecting electrode, and the end protrudes from the collecting electrode along the second direction, and the protrusion length H is greater than 120μm and less than 150μm. Preferably, the protrusion length H is 121μm, 125μm, 128μm, 130μm, 132μm, 135μm, 138μm, 140μm, 142μm, 145μm, 148μm, or 150μm.

[0046] According to any embodiment of the second aspect of the present invention, the area formed by the disconnection of the anisotropic collector electrode along the second direction is the confluence area, and the length D1 of the collector electrode disconnection is ≥ 0.6 mm and ≤ 1.5 mm. Preferably, the length D1 is 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm. Correspondingly, the retracted length D2 is 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm.

[0047] According to any embodiment of the second aspect of the present invention, any bus electrodes extending along the second direction have the same length or the number of bus electrodes coupled to the collecting electrodes is the same.

[0048] According to any embodiment of the second aspect of the present invention, an insulating array is covered on the opposite-sex collecting electrodes in the bus region.

[0049] The third aspect of the present invention provides a back-contact solar cell, including a cell substrate, the cell substrate having a light-facing surface and a backlight surface, the backlight surface including a back-contact electrode structure, and the back-contact electrode structure is the back-contact electrode structure described in the first aspect or the back-contact electrode structure described in the second aspect.

[0050] According to any embodiment of the third aspect of the present invention, it also includes conductive materials above the circular edge busbars on both sides of the battery substrate along the first direction and welding strips for interconnecting the battery cells.

[0051] According to any embodiment of the third aspect of the present invention, when at least part of the bus area welding strip contacts the bus point, there is no other conductive material except the bus electrode or welding strip at the intermediate interface; at the interface between the circular edge bus point and the welding strip, there is a printed circular conductive material, the circular diameter of which is ≥0.3mm and ≤0.8mm. Preferably, the circular diameter is 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm.

[0052] A fourth aspect of the present invention provides a photovoltaic module, comprising: The back contact solar cell according to the third aspect; Along the second direction, the welding strip extends from the side with the bus electrode to the other side of the battery cell and is connected to another battery cell; the welding strip at the edge connected to the circular edge bus point extends in the opposite direction to the adjacent bus area welding strip.

[0053] According to any embodiment of the fourth aspect of the present invention, the bus area welding strip is coupled and intersected with the bus electrode, and the intersection length is ≥1 / 7 of the bus electrode length and ≤1 / 2 of the bus electrode length. Preferably, the intersection length is 1 / 7 of the bus electrode length, 1 / 6 of the bus electrode length, 1 / 5 of the bus electrode length, 1 / 4 of the bus electrode length, 1 / 3 of the bus electrode length, and 1 / 2 of the bus electrode length; and / or, the number of common coupling points between the welding strip and the bus point, the collector electrode, and the bus electrode is ≥1 and ≤4, preferably, the number of coupling points is 1, 2, 3, or 4. The above welding strip extends along the second direction and is locally welded at the edge of the battery substrate, which effectively solves the battery warping problem; and while ensuring the welding strength, the carriers collected by the bus electrode can be effectively output; in addition, the local coupling and intersection of the welding strip and the bus electrode can effectively avoid the problem of fragments that may be generated at the edge of the battery substrate.

[0054] 3. Beneficial effects Compared with the prior art, the present invention has the following beneficial effects: (1) In the back contact electrode structure of the present invention, the collector electrode of the same polarity extends to the edge of the battery substrate, while the collector electrode of the other polarity does not extend to the edge of the battery substrate. This facilitates the collection of more carriers on the collector electrode, effectively avoiding the short circuit problem and maximizing the space utilization of the battery substrate.

[0055] (2) The back contact electrode structure of the present invention has the following characteristics: the extension lines of the centers of the first edge bus electrode and the second edge bus electrode on both sides of the battery substrate along the first direction are horizontal and do not intersect; the edge bus points are connected to the collector electrodes of the same polarity, which increases the effective contact area with the welding strip and improves the welding strength.

[0056] (3) The back contact electrode structure of the present invention, through the above-mentioned structural design, the hollow busbars in the middle busbar area and part of the busbar electrode are welded to the welding strip, and the edge busbars are partially connected to the welding strip; this design reduces the contact area between the welding strip and the battery cell in the adjacent area, which can effectively reduce the battery welding warping problem, improve the battery reliability, and improve the battery efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments, but it should be understood that these drawings are designed only for explanation purposes and are not intended to limit the scope of the present invention. In addition, unless otherwise specified, these drawings are intended only to conceptually illustrate the structural configurations described herein and are not necessarily drawn to scale.

[0058] Figure 1 A schematic diagram of the main grid solar cell structure of the related technology; Figure 2 A schematic diagram of a busbar-free solar cell structure in the related art; Figure 3 It is a schematic structural diagram of a back contact solar cell of the present invention; Figure 4 It is a schematic diagram of the marked structure of the back contact solar cell of the present invention; Figure 5 for Figure 3 An enlarged view of an implementation structure of part A; Figure 6 for Figure 3 Another embodiment of the structure of the A part is enlarged; Figure 7 The local structure of the back contact solar cell of the present invention is enlarged Figure 1 ; Figure 8 The local structure of the back contact solar cell of the present invention is enlarged Figure 2 ; Fig. 9 The local structure of the back contact solar cell of the present invention is enlarged Figure 3 ; Fig.10 It is a front view of a back contact solar cell of the present invention; Fig.11 is a schematic diagram of the comparative structure of the back contact solar cell of the present invention; Fig.12 Another schematic diagram of the structure of the back contact solar cell of the present invention; Fig.13 It is a schematic structural diagram of a back contact solar cell and a soldering ribbon combination of the present invention; Fig.14 This is a schematic diagram of the structure of a photovoltaic module formed by connecting solar cells in series according to the present invention; Description of reference numerals: 10. Battery cell; 11. Battery substrate; 12. First bus electrode; 13. Second bus electrode; 14. First collecting electrode; 15. Second collecting electrode; 16. First bus point; 17. Second bus point; 18. First edge bus point; 19. First edge bus electrode; 20. First edge collecting electrode; 21. Second edge bus point; 22. Second edge bus electrode; 23. Second edge collecting electrode; 24. First bus area; 25. Second bus area; 26. First welding strip; 27. Second welding strip; 28. First insulating array; 29. ​​Bent collecting electrode; 30. Circular conductive material; 31. Second insulating array; 32. Diamond frame; 33. Vertical center line; 34. First straight bus electrode; 35. Second straight bus electrode. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0060] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0062] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0063] In addition, the terms "horizontal" and "vertical" do not mean that the components must be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0064] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0065] Solar cells are now being used more and more widely as a new energy alternative. Among them, photovoltaic solar cells are devices that convert sunlight into electrical energy. In the actual working process, solar cells use the photovoltaic principle to generate carriers, and then use electrodes to lead the carriers out, thereby facilitating the effective use of electrical energy.

[0066] A back-contact solar cell is a cell structure in which the positive and negative electrodes are arranged on the non-light-receiving side of the cell. Since there is no grid line blocking the front of this type of cell, it effectively increases the collection of solar energy and improves the short-circuit current of the cell 10. In the related art, in order to realize the interconnection of cell components, back-contact solar cells usually adopt two electrode designs: with a main grid and without a main grid.

[0067] Among them, the battery design with main grid is as follows Figure 1The design usually adopts the main grid busbar and pad welding method. This method reduces the carrier transfer resistance of the main grid. The main grid design is usually wide, which results in a higher silver paste consumption per unit, increasing the cost. In addition, this design has a large current transfer resistance in the main grid area and a high efficiency loss. If the main grid is too wide and contacts the welding strip, the battery cell 10 will have a serious warping problem and there will be a reliability risk.

[0068] Another is like Figure 2 The conventional busbar-free welding method requires printing an insulating array on the opposite-sex electrode. The height of this type of array is usually 20-30μm. A thicker solder paste array must be printed on the same-sex electrode to achieve solder ribbon interconnection. A silver electrode substrate is also required at the bottom of the solder paste. Low-temperature lamination must be selected for component lamination, which makes the component manufacturing process complicated and increases the reliability risk. In addition, the large-area contact between the high-density solder paste and the solder ribbon will also cause serious battery warping, leading to component reliability risks.

[0069] Patent document CN118431305A discloses a solar cell, which includes a battery substrate, a collector electrode, a bus electrode segment and a first welding portion. The collector electrode extends along a first direction, and different collector electrodes on the same target surface of the battery substrate are spaced along a second direction. The bus electrode segment is located on the edge regions at both ends of the target surface along the second direction, and the bus electrode segment extends along the second direction. Every two bus electrode segments at different ends of the same target surface along the second direction are arranged opposite to each other. The bus electrode segment is electrically coupled to the corresponding collector electrode of the same conductive type as itself. The first welding portion is arranged on the side of the corresponding bus electrode segment away from the edge of the battery substrate along the second direction, and is electrically coupled to the corresponding bus electrode segment. The patent discloses that the connection strength is improved by welding the rectangular first welding portion with the welding interconnection member, and the rectangular first welding portion is arranged on the battery substrate by printing, but this method is easy to cause corrosion of the battery substrate, and holes are easy to appear on the interface, which is not conducive to the complete extraction of carriers in severe cases.

[0070] Combination Figures 3 to 14 As shown, the back contact solar cell 10 of this embodiment includes a cell substrate 11, wherein the cell substrate 11 has a light-facing surface and a backlight surface, wherein the backlight surface includes a back contact electrode structure, and the back contact electrode structure includes a collector electrode, a bus electrode, a bus point and a bus region. Figures 3 to 6 As shown, the battery substrate 11 has a first direction and a second direction in two dimensions, wherein the first direction is different from the second direction.

[0071] like Figure 3As shown, the first collecting electrode 14 and the second collecting electrode 15 extend along the first direction, and the first collecting electrode 14 and the second collecting electrode 15 are designed to be alternately spaced along the second direction; for the above-mentioned first collecting electrode 14 and the second collecting electrode 15, the embodiment of the present invention does not specifically limit the morphology, quantity and distribution of the first collecting electrode 14 and the second collecting electrode 15, which can be determined according to the type of solar cell and the actual application scenario.

[0072] exist Figure 3 and Figure 4 In the embodiment, the first bus electrode 12 and the second bus electrode 13 are distributed on both sides of the battery substrate 11 along the second direction, the first bus electrode 12 of the same polarity is distributed on one side of the edge of the battery substrate 11, and the second bus electrode 13 of the other polarity is distributed on the other side, the first bus electrode 12 and the second bus electrode 13 are distributed in an array along the first direction, and are coupled with the first collector electrode 14 or the second collector electrode 15 of the same polarity extending along the first direction. The carriers collected by the first collector electrode 14 or the second collector electrode 15 can be converged to the first bus electrode 12 and the second bus electrode 13.

[0073] When the above technical solution is adopted, Figure 3 and Figure 4 As shown, the first edge collector electrode 20 and the second edge collector electrode 23 extending in the second direction are designed at the edges of both sides of the battery substrate 11 along the second direction, and are coupled with the first collector electrode 14 or the second collector electrode 15 extending in the first direction. The carriers collected by the first collector electrode 14, the second collector electrode 15, the first edge collector electrode 20 and the second edge collector electrode 23 located at the edge region at one end along the second direction can be converged to the first edge bus electrode 19 and the second edge bus electrode 22.

[0074] exist Figure 3 In the embodiment, no busbar electrodes extending along the second direction are designed at the edges of both sides of the battery substrate 11 along the first direction; a first edge busbar point 18, a second edge busbar point 21, a first edge busbar electrode 19 and a second edge busbar electrode 22 are designed at the edges of both sides of the battery substrate 11 along the second direction.

[0075] When the above technical solution is adopted, Figure 3 and Fig.13As shown, the first bus point 16 and the second bus point 17 are distributed in an array along the first direction and the second direction, and in the array area extending along the second direction, there are only first bus points 16 or second bus points 17 of the same polarity; the area where the first bus point 16 is coupled with the first collecting electrode 14 is designed as a first bus area 24, and the area where the second bus point 17 is coupled with the second collecting electrode 15 is designed as a second bus area 25, which are respectively used for welding the first welding strip 26 or the second welding strip 27, and there is no gap between the first welding strip 26 or the second welding strip 27 and the first bus point 16 or the second bus point 17, so there is no need to use conductive glue or other materials to fill it, so as to avoid corrosion of the battery substrate 11.

[0076] Based on this, Fig.14 As shown, after the solar cell sheets 10 provided by the embodiment of the present invention are connected in series to form a photovoltaic module, the first welding strip 26 or the second welding strip 27 is welded together with the first busbar 16 and the second busbar 17 to collect the carriers collected by the first collecting electrode 14 and the second collecting electrode 15 located on the edge areas on both sides along the second direction. The end of the first welding strip 26 or the second welding strip 27 does not need to extend to the edge areas on both ends of the battery substrate 11 along the second direction at the same time, thereby shortening the effective welding length of the first welding strip 26 or the second welding strip 27 and the battery substrate 11, which is beneficial to reducing the welding stress in the edge area of ​​the battery substrate 11 along the second direction, thereby reducing the risk of welding failure.

[0077] It should be emphasized that in order to improve the welding tension between the first busbar 16 and the second busbar 17 and the first welding strip 26 or the second welding strip 27, the reliability of the battery cell 10 is effectively improved. Figure 3 , Figure 5 , Figure 6 and Figure 8 As shown, specifically taking the first bus point 16 as an example, the first bus point 16 in the first bus area 24 along the first direction of the battery substrate 11 is a hollow design, and the hollow design has a corresponding structural shape (the projected shape is a rhombus or an ellipse), for example, the hollow design includes a rhombus frame 32 (or an elliptical frame) and the blank area in the figure is shown as a hollow part, the first collector electrode 14 passes through the center point of the bus point, and is coupled with the vertical midline 33 of the center of the first bus point 16 along the second direction. Similarly, taking the second bus point 17 as an example, the second bus point 17 in the second bus area 25 along the first direction of the battery substrate 11 is a rhombus hollow design, the second collector electrode 15 passes through the center point of the bus point, and is coupled with the vertical midline 33 of the center of the second bus point 17 along the second direction.

[0078] What surprised the inventors is that, firstly, the hollow design of the first confluence point 16 can also optimize the carrier distribution and reduce the welding stress concentration; the above hollow design can also reduce the use of corresponding materials, thereby reducing the production cost of the battery. Secondly, the above hollow design reduces the contact area between the first confluence point 16 and the battery substrate 11, thereby reducing the corrosion of the welding strip metal to the battery substrate 11, which is beneficial to the performance guarantee of the battery substrate 11; in addition, for example, the first collector electrode 14 runs through the center point of the confluence point, and the total amount of silver paste at the welding point increases, so that the contact surface between the welding strip and the silver paste increases, shortening the transmission path of the carriers, which is beneficial to the transmission loss of the carriers collected by the first collector electrode 14 to the welding strip, so that the solar cell has a larger open circuit voltage.

[0079] According to the current data analysis, the above hollowing design has almost no influence on the current stability and efficiency of the solar cell 10 of the present invention.

[0080] In addition, through a large number of tests, it was found that the diamond hollow design, the converging current design and the welding strip will form localized contact, which can effectively reduce the contact area per unit area. Although the welding tension at a single point is reduced, the more uniform welding simultaneously reduces the tensile force per unit area, thereby reducing the risk of demolding caused by welding tension, and effectively solving the risk of back contact battery welding reliability.

[0081] In this embodiment, specifically, Figure 5 As shown, the length L of the first busbar 16 along the first direction is 0.6mm, 0.7mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, 1.6mm, 1.8mm, 1.9mm, 2mm; preferably 1.0mm. The above structure can further improve the contact area between the first busbar 16 and the battery substrate 11, thereby reducing the contact resistance between the two and reducing the transmission loss.

[0082] As a possible implementation, Figure 5 and Figure 6 As shown, the total area formed by the outer contour of the first confluence point 16 with a diamond-shaped hollow design is 0.01mm 2 , 0.02mm 2 , 0.03mm 2 , 0.04mm 2 , 0.05mm 2 , 0.06mm 2 , 0.07mm 2 、0.08mm 2 、0.09mm 2 , 0.1mm 2 , 0.15mm 2 , 0.2mm2 , 0.25mm 2 , 0.35mm 2 , 0.45mm 2 , 0.55mm 2 、0.65mm 2 , 0.7mm 2 , 0.8mm 2 , 0.9mm 2 , 1mm 2 , preferably 0.1 mm 2 The beneficial effects in this case can be referred to the beneficial effects analysis of the length limitation of the first confluence point 16 along the first direction in the above text, which will not be repeated here.

[0083] As a possible implementation scheme, the area of ​​the non-hollowed part of the diamond hollow design accounts for 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, in this case, it is beneficial to increase the contact area between the first confluence point 16 and the battery substrate 11 and reduce the transmission loss. At the same time, it can also improve the connection stability between the first confluence point 16 and the battery substrate 11 and improve the reliability of the solar cell structure.

[0084] In this embodiment, if Figure 3 As shown, the first collecting electrode 14 or the second collecting electrode 15 is disconnected along the second direction in the non-isotropic confluence area, and the disconnection length is D1; ​​along the second direction, on both sides of the battery substrate 11, the distance from the non-isotropic first collecting electrode 14 or the second collecting electrode 15 extending along the second direction is retracted, and the retracted length is D2, and D2=D1 / 2.

[0085] Specifically, in the embodiment of the present invention, the area formed by the disconnection of the first collector electrode 14 or the second collector electrode 15 along the second direction is the confluence area, and the disconnected length D1 of the first collector electrode 14 or the second collector electrode 15 is 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm. Correspondingly, the retracted length D2 is 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm.

[0086] At this time, further, insulating materials are provided at the disconnection of the second collector electrode 15 that is not electrically coupled to the first bus electrode 12, and at the disconnection of the first collector electrode 14 that is not electrically coupled to the second bus electrode 13, collectively referred to as the first insulating array 28. Figure 3 and Figure 8 shown.

[0087] The type and size of the insulating material of the first insulating array 28 can be determined according to the actual application scenario and are not specifically limited here. For example, the insulating material can be insulating glue or the like.

[0088] In the above situation, the welding strip can be separated from the conductive type opposite to itself by providing insulating material or disconnecting the strip to prevent short circuit.

[0089] Furthermore, the ratio of the sum of the disconnected lengths of the same row, the same first collecting electrode 14 or the second collecting electrode 15 to the length L0 of the battery substrate 11 along the first direction is 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, or 0.2.

[0090] Combination Figure 4 As shown, the collecting electrodes of the same polarity extending along the first direction have a segmented design, and the length W1 of the collecting electrodes on both sides of the battery substrate 11 along the first direction is less than the length W2 of other collecting electrodes (marked as W2' and W2'' in the figure), and the other collecting electrodes include adjacent opposite-sex collecting electrodes and same-sex collecting electrodes away from the edge of the battery substrate. Specifically, the length W1 of the first collecting electrodes 14 on both sides (the parts covered by the light and dark colors) is 10mm, the length W2' of the adjacent opposite-sex second collecting electrodes 15 (the parts covered by the light colors) is 15mm, 16mm, 17mm, 18mm, 19mm, or the length W2'' of the same-sex collecting electrodes (the parts covered by the light colors) away from the edge of the battery substrate is 15mm, 16mm, 17mm, 18mm, 19mm.

[0091] In the above structural design, the collecting electrodes of the same polarity extend to the edge of the battery substrate, while the collecting electrodes of the other polarity do not extend to the edge of the battery substrate. This can facilitate the collection of more carriers on the collecting electrodes, which not only effectively avoids the short circuit problem, but also maximizes the space utilization of the battery substrate.

[0092] like Figure 4 As shown, the length of the first edge collector electrode 20 or the second edge collector electrode 23 extending along the second direction on both sides of the battery substrate 11 is L1*100%, L1*95% or L1*90% of the length of the battery substrate 11 along the second direction. The first edge collector electrode 20 or the second edge collector electrode 23 is continuous, which can increase the carrier collection efficiency of the first edge collector electrode 20 or the second edge collector electrode 23 while preventing short circuit, and ensure that the carrier recombination rate of the edge area along the second direction is small.

[0093] In this embodiment, if Figure 4 As shown, the bus electrodes on both sides of the second direction of the battery substrate 11 are distributed in an array along the second direction, and one side is the first bus electrode 12, and the other side is the second bus electrode 13; the length L2 of the first bus electrode 12 or the second bus electrode 13 on both sides along the first direction is 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3.0mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, and 4mm.

[0094] Alternatively, the length of the first bus electrode 12 or the second bus electrode 13 can be converted into a total area, wherein the total area of ​​the first bus electrode 12 or the second bus electrode 13 is 0.5 mm 2 , 0.6mm 2 , 0.7mm 2 , 0.8mm 2 , 0.9mm 2 , 1.0mm 2 , 1.1mm 2 , 1.2mm 2 , 1.3mm 2 , 1.4mm 2 , 1.5mm 2 , 1.6mm 2 , 1.7mm 2 , 1.8mm 2 , 1.9mm 2 , 2mm 2 .

[0095] In this case, the total area is within the above range, which can prevent the metal composite area between the bus electrode and the battery substrate 11 from being larger due to the larger area of ​​the bus electrode, thereby ensuring that the solar cell has a larger open circuit voltage; at the same time, it can also reduce the amount of consumables used in the manufacture of the bus electrode.

[0096] Combination Fig. 9 and Fig.10 As shown, any extension lines of the centers of the first edge bus electrodes and the second edge bus electrodes on both sides of the battery substrate 11 along the first direction are horizontal and do not intersect, and the horizontal spacing L3 of the center lines extending from the two nearest first edge bus electrodes to the second edge bus electrodes along the first direction is 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.8mm, 2.9mm, 3mm, preferably 0.4mm.

[0097] The above-mentioned collector electrodes are distributed on the battery substrate at equal intervals along the second direction. On both sides of the battery substrate along the first direction, in order to improve the extraction efficiency of carriers, the collector electrodes, edge collector electrodes and edge bus electrodes of the same polarity are coupled with each other to extract these carriers. However, when the edge bus electrodes are on the same plane, their edge bus points will cross two collector electrodes of different polarities, such as Fig.11 As shown, this design is not only easy to cause short circuits, but also forms a poor contact area. At the same time, the effective contact area between the edge busbar and the welding strip is small, which increases the transmission loss. Therefore, the extension lines of the centers of the first edge busbar electrodes and the second edge busbar electrodes on both sides of the battery substrate 11 along the first direction of the present invention are horizontal and do not intersect. The edge busbar is connected to the collector electrode of the same polarity, and the effective contact area with the welding strip is increased, thereby improving the welding strength.

[0098] exist Fig. 9 In the figure, the edge bus points on both sides of the battery substrate 11 along the first direction are coupled with the bus electrodes extending along the first direction at the edge, and are coupled with part of the collecting electrodes along the first direction; the edge bus points are circular solid design with diameters of 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, and 1mm; the number of the edge bus points and the coupled collecting electrodes is 1, 2, or 3.

[0099] Based on this, Fig.13As shown, the first welding strip 26 or the second welding strip 27 is welded together with the first edge bus 18 and the second edge bus 21 to collect the carriers collected by the first edge collecting electrode 20 and the second edge collecting electrode 23 located on the edge area at one end along the first direction. The end of the first welding strip 26 or the second welding strip 27 does not need to extend to the edge areas at both ends of the battery substrate 11 along the first direction at the same time, thereby shortening the effective welding length of the first welding strip 26 or the second welding strip 27 and the battery substrate 11, which is beneficial to reducing the welding stress in the edge area of ​​the battery substrate 11 along the first direction, thereby reducing the risk of welding failure.

[0100] like Figure 8 and Fig. 9 As shown, the collecting electrode at the edge of the battery substrate 11 along the first direction has a bending design, which is a bent collecting electrode 29, and its bending angle a is 90°, 95°, 100°, 105°, 110°, 115°, 120°, 125°, 130°, 135°, 140°, 150°, 155°, 160°, 165°, 170°, 175°, 179°, preferably 150°.

[0101] In some embodiments of the present invention, collector electrodes of different polarities use different conductive materials; bus electrodes and bus points of different polarities use the same conductive material. Further, hollow bus points of different polarities use the same conductive material as the collector electrodes coupled thereto, and circular bus points and bus electrodes of different polarities use the same conductive material.

[0102] like Figure 3 As shown, the seven bus points are coupled simultaneously with the first collecting electrode 14 along the second direction and the first bus electrode 12 extending along the second direction.

[0103] Specifically, the bus electrode gradually changes along the second direction and is coupled with the seven collecting electrodes; the gradual change of the bus electrode always extends from the edge of the battery substrate 11 to the inside of the battery, and the minimum value of the gradual change of the width along the first direction is 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm, 51μm, 52μm, 53μm, 54μm, 55μm, 56μm, 57μm, 58μm, 59μm, 60 μm, 61μm, 62μm, 63μm, 64μm, 65μm, 66μm, 67μm, 68μm, 69μm, 70μm, 71μm, 72μm, 73μm, 74μm, 75μm, 76μm, 77μm, 78μm, 79μm, 80μm; along the first direction The maximum value of the width gradient is 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, 210μm, 220μm, 230μm, 240μm, 250μm, 260μm, 270μm, 280μm, 290μm, 295μm, 300μm.

[0104] In this case, the first bus electrode 12 or the second bus electrode 13 is a gradient design, which is beneficial to increase the contact area between the bus electrode segment and the battery substrate 11 and reduce transmission loss; at the same time, it can also improve the connection stability between the bus electrode and the welding strip and enhance the reliability of the solar cell structure.

[0105] like Figure 7 As shown, on both sides of the edge of the battery substrate 11, the first bus electrode 12 is coupled with the same-sex collector electrode, and the end protrudes from the first collector electrode 14 along the second direction, and the protrusion length H is 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm. Similarly, the second bus electrode 13 is coupled with the same-sex collector electrode, and the end protrudes from the second collector electrode 15 along the second direction, and the protrusion length H is 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm.

[0106] Within the above-mentioned numerical range, it can be prevented that the distance is too large, resulting in the end of the bus electrode segment close to the edge area along the second direction being close to the end of the battery substrate 11, which may lead to the problem of bus electrode overlap short circuit after two adjacent solar cells are connected in series; in addition, it can also be prevented that the distance is too large, resulting in a small distance between the end of the bus electrode close to the edge area along the second direction and the collector electrode with the opposite conductivity type and located at the outermost side of the edge area along the second direction, which may lead to a greater risk of leakage, thereby ensuring that the back-contact battery has higher electrical reliability.

[0107] Furthermore, in this embodiment, in order to better guide the carriers, any bus electrodes extending along the second direction have the same length or the same number of couplings between the bus electrodes and the collector electrodes, for example, the first bus electrode 12 and the second bus electrode 13 have the same length, and the two adjacent first bus electrodes 12 on the same side have the same length. For another example, the number of couplings between two adjacent first bus electrodes 12 and the first collector electrode 14 is seven.

[0108] In addition, in some possible embodiments, Fig.12 As shown, the first bus electrode 12, the second bus electrode 13, the first bus point 16 and the second bus point 17 are connected by the first straight bus electrode 34 and the second straight bus electrode 35, and then connected to the welding strip.

[0109] Combination Figure 8 and Fig.14 As shown, the photovoltaic module of this embodiment includes: the above-mentioned back-contact solar cell 10; a second insulating array 31 covering the opposite-type collecting electrode in the bus area, which can be separated from the bus electrode of the opposite conductivity type by the insulating material of the second insulating array 31 to prevent short circuit; conductive material above the circular edge bus points on both sides of the battery substrate 11 along the first direction and welding strips for interconnecting the battery cells 10.

[0110] The type and size of the insulating material of the second insulating array 31 can be determined according to the actual application scenario and are not specifically limited here. For example, the insulating material can be insulating glue or the like.

[0111] Along the second direction, the welding strip extends from the side with the bus electrode to the other side of the battery cell 10 and is connected to another battery cell; the welding strip connected to the circular edge bus point at the edge extends in the opposite direction to the welding strip of the adjacent bus area.

[0112] When the bus area welding strip contacts the hollow bus point, there is no other conductive material contained in the bus electrode or welding strip at the intermediate interface except for the bus electrode or welding strip; at the interface between the circular edge bus point and the welding strip, there is a printed circular conductive material 30; its circular diameter is 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, and 0.8mm.

[0113] Furthermore, the bus area welding strip is coupled and intersected with the bus electrode, and the intersection length is 1 / 7 of the bus electrode length, 1 / 6 of the bus electrode length, 1 / 5 of the bus electrode length, 1 / 4 of the bus electrode length, 1 / 3 of the bus electrode length, and 1 / 2 of the bus electrode length.

[0114] Among them, the number of common coupling points between the welding strip and the busbar, the collecting electrode, and the busbar electrode is 1, 2, 3, or 4.

[0115] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A back contact electrode structure, comprising a collector electrode, a bus electrode, a bus point and a bus area, wherein: The collector electrodes extend along a first direction, and the collector electrodes of different polarities are alternately arranged along a second direction; The bus electrodes are distributed on both sides of the battery substrate along the second direction, the bus electrodes of the same polarity are distributed on one side of the edge of the battery substrate, and the bus electrodes of the other polarity are distributed on the other side, and the bus electrodes of different polarities are distributed in an array along the first direction and are coupled with the collector electrodes of the same polarity extending along the first direction; Edge collector electrodes extending along the second direction are designed at both side edges of the battery substrate along the second direction, and are coupled with the collector electrodes extending along the first direction; Designing edge bus points and edge bus electrodes at the edges of both sides of the battery substrate along the second direction; The bus points are distributed in an array along the first direction and the second direction, and in the array area extending along the second direction, there are only bus points of the same polarity; the area where the bus points are coupled with the collector electrodes is designed as a bus area for welding with welding strips; it is characterized in that, At least part of the collecting electrodes extending along the first direction have a segmented design, and the length W1 of the collecting electrodes on both sides of the battery substrate along the first direction is less than the length W2 of other collecting electrodes, and the other collecting electrodes include adjacent opposite-sex collecting electrodes and same-sex collecting electrodes away from the edge of the battery substrate.

2. The back contact electrode structure according to claim 1, characterized in that: The confluence point in the confluence area along the first direction of the battery substrate is hollowed out, the collector electrode passes through the center point of the confluence point, and is coupled with a vertical midline of the center of the confluence point along the second direction.

3. The back contact electrode structure according to claim 2, characterized in that: The length L of the confluence point along the first direction is ≥ 0.6 mm and ≤ 2 mm; and / or the total area formed by the outer contour of the confluence point of the hollow design is ≥ 0.01 mm 2 , and ≤1mm 2 .

4. The back contact electrode structure according to claim 3, characterized in that: The non-hollowed-out area of ​​the hollowed-out design accounts for ≥5% and <100% of the total area of ​​the confluence point.

5. The back contact electrode structure according to any one of claims 1 to 4, characterized in that: The collecting electrode is disconnected along the second direction in the non-isotropic confluence area, and the disconnection length is D1; ​​along the second direction, both sides of the battery substrate are retracted from the non-isotropic collecting electrodes extending along the second direction, and the retracted length is D2, and D2≤D1 / 2; and / or, the ratio of the sum of the disconnection lengths of the same row and the same collecting electrode to the length L0 of the battery substrate along the first direction is ≥0.05 and ≤0.

2.

6. The back contact electrode structure according to claim 5, characterized in that: The length of the edge collector electrodes extending along the second direction on both sides of the battery substrate is ≤ L1*100% of the length of the battery substrate along the second direction, and ≥ L1*90% of the length of the battery substrate along the second direction.

7. The back contact electrode structure according to claim 6, characterized in that: The bus electrodes on both sides of the second direction of the battery substrate are arranged in an array along the second direction, and have the same polarity on one side and another polarity on the other side; the length L2 of the bus electrodes on both sides along the first direction is ≥2mm and ≤4mm; and / or the total area of ​​the bus electrodes is ≥0.5mm 2 , and ≤2mm 2 .

8. The back contact electrode structure according to claim 7, characterized in that: The edge bus points on both sides of the battery substrate along the first direction are coupled with the bus electrodes extending along the first direction, and are coupled with part of the collecting electrodes along the first direction; the edge bus points are circular solid designs with a diameter ≥0.5mm and ≤1mm; the number of collector electrodes coupled with the edge bus points is ≥1 and ≤3.

9. The back contact electrode structure according to claim 8, characterized in that: The current collecting electrode at the outermost edge of the battery substrate along the first direction has a bending design, and the bending angle is ≥90° and <180°.

10. The back contact electrode structure according to claim 9, characterized in that: Collecting electrodes of different polarities use different conductive materials; bus electrodes and bus points of different polarities use the same conductive material; and / or: hollow bus points of different polarities use the same conductive material as the collector electrodes coupled thereto, and circular edge bus points and bus electrodes of different polarities use the same conductive material.

11. The back contact electrode structure according to claim 10, characterized in that: At least one bus point is coupled with the collector electrode along the second direction and the bus electrode extending along the second direction at the same time, and the number of coupling points is ≥1 and ≤10.

12. The back contact electrode structure according to claim 11, characterized in that: The bus electrode with a gradient along the second direction is coupled with at least one collecting electrode; the gradient of the bus electrode always extends from the edge of the battery substrate to the inside of the battery, and the minimum value of the width gradient along the first direction is ≥30μm and ≤80μm; the maximum value of the width gradient along the first direction is ≥150μm and ≤300μm.

13. The back contact electrode structure according to claim 12, characterized in that: At the edge of the battery substrate, the bus electrode is coupled to a collector electrode of the same sex, and the end thereof protrudes from the collector electrode along the second direction, and the protrusion length H is greater than 120 μm and less than or equal to 150 μm.

14. The back contact electrode structure according to claim 13, characterized in that: The area formed by the disconnection of the anisotropic collector electrode along the second direction is the confluence area, and the length D1 of the disconnection of the collector electrode is ≥0.6 mm and ≤1.5 mm.

15. The back contact electrode structure according to claim 14, characterized in that: Any bus electrodes extending along the second direction have the same length or the number of bus electrodes coupled with the collector electrodes is the same.

16. The back contact electrode structure according to claim 15, characterized in that: An insulating array is covered on the opposite-sex collecting electrodes in the bus area.

17. A back contact electrode structure, comprising a collector electrode, a bus electrode, a bus point and a bus region, wherein: The collector electrodes extend along a first direction, and the collector electrodes of different polarities are alternately arranged along a second direction; The bus electrodes are distributed on both sides of the battery substrate along the second direction, the bus electrodes of the same polarity are distributed on one side of the edge of the battery substrate, and the bus electrodes of the other polarity are distributed on the other side, and the bus electrodes of different polarities are distributed in an array along the first direction and are coupled with the collector electrodes of the same polarity extending along the first direction; Edge collector electrodes extending along the second direction are designed at both side edges of the battery substrate along the second direction, and are coupled with the collector electrodes extending along the first direction; Designing edge bus points and edge bus electrodes at the edges of both sides of the battery substrate along the second direction; The bus points are distributed in an array along the first direction and the second direction, and in the array area extending along the second direction, there are only bus points of the same polarity; the area where the bus points are coupled with the collector electrodes is designed as a bus area for welding with welding strips; it is characterized in that, Any extension lines of the centers of the edge bus electrodes on both sides of the battery substrate along the first direction are horizontal and do not intersect, and the horizontal spacing L3 between the center lines of the two nearest opposite edge bus electrodes extending along the first direction is ≥0.4mm and ≤3mm.

18. The back contact electrode structure according to claim 17, characterized in that: The confluence point in the confluence area along the first direction of the battery substrate is hollowed out, the collector electrode passes through the center point of the confluence point, and is coupled with a vertical midline of the center of the confluence point along the second direction.

19. The back contact electrode structure according to claim 18, characterized in that: The length L of the confluence point along the first direction is ≥ 0.6 mm and ≤ 2 mm; and / or the total area formed by the outer contour of the confluence point of the hollow design is ≥ 0.01 mm 2 , and ≤1mm 2 .

20. The back contact electrode structure according to claim 19, characterized in that: The non-hollowed-out area of ​​the hollowed-out design accounts for ≥5% and <100% of the total area of ​​the confluence point.

21. The back contact electrode structure according to any one of claims 17 to 20, characterized in that: The collecting electrode is disconnected along the second direction in the non-isotropic confluence area, and the disconnection length is D1; ​​along the second direction, both sides of the battery substrate are retracted from the non-isotropic collecting electrodes extending along the second direction, and the retracted length is D2, and D2≤D1 / 2; and / or, the ratio of the sum of the disconnection lengths of the same row and the same collecting electrode to the length L0 of the battery substrate along the first direction is ≥0.05 and ≤0.

2.

22. The back contact electrode structure according to claim 21, characterized in that: The length of the edge collector electrodes extending along the second direction on both sides of the battery substrate is ≤ L1*100% of the length of the battery substrate along the second direction, and ≥ L1*90% of the length of the battery substrate along the second direction.

23. The back contact electrode structure according to claim 22, characterized in that: The bus electrodes on both sides of the second direction of the battery substrate are arranged in an array along the second direction, and have the same polarity on one side and another polarity on the other side; the length L2 of the bus electrodes on both sides along the first direction is ≥2mm and ≤4mm; and / or the total area of ​​the bus electrodes is ≥0.5mm 2 , and ≤2mm 2 .

24. The back contact electrode structure according to claim 23, characterized in that: The edge bus points on both sides of the battery substrate along the first direction are coupled with the bus electrodes extending along the first direction, and are coupled with part of the collecting electrodes along the first direction; the edge bus points are circular solid designs with a diameter ≥0.5mm and ≤1mm; the number of collector electrodes coupled with the edge bus points is ≥1 and ≤3.

25. The back contact electrode structure according to claim 24, characterized in that: The current collecting electrode at the outermost edge of the battery substrate along the first direction has a bending design, and the bending angle is ≥90° and <180°.

26. The back contact electrode structure according to claim 25, characterized in that: Collecting electrodes of different polarities use different conductive materials; bus electrodes and bus points of different polarities use the same conductive material; and / or: hollow bus points of different polarities use the same conductive material as the collector electrodes coupled thereto, and circular edge bus points and bus electrodes of different polarities use the same conductive material.

27. The back contact electrode structure according to claim 26, characterized in that: At least one bus point is coupled with the collector electrode along the second direction and the bus electrode extending along the second direction at the same time, and the number of coupling points is ≥1 and ≤10.

28. The back contact electrode structure according to claim 27, characterized in that: The bus electrode with a gradient along the second direction is coupled with at least one collecting electrode; the gradient of the bus electrode always extends from the edge of the battery substrate to the inside of the battery, and the minimum value of the width gradient along the first direction is ≥30μm and ≤80μm; the maximum value of the width gradient along the first direction is ≥150μm and ≤300μm.

29. The back contact electrode structure according to claim 28, characterized in that: At the edge of the battery substrate, the bus electrode is coupled to a collector electrode of the same sex, and the end thereof protrudes from the collector electrode along the second direction, and the protrusion length H is greater than 120 μm and less than or equal to 150 μm.

30. The back contact electrode structure according to claim 29, characterized in that: The area formed by the disconnection of the anisotropic collector electrode along the second direction is the confluence area, and the length D1 of the disconnection of the collector electrode is ≥0.6 mm and ≤1.5 mm.

31. The back contact electrode structure according to claim 30, characterized in that: Any bus electrodes extending along the second direction have the same length or the number of bus electrodes coupled with the collector electrodes is the same.

32. The back contact electrode structure according to claim 31, characterized in that: An insulating array is covered on the opposite-sex collecting electrodes in the bus area.

33. A back-contact solar cell comprising a cell substrate, the cell substrate having a light-facing surface and a back-light surface, the back-light surface comprising a back-contact electrode structure, characterized in that: The back contact electrode structure is the back contact electrode structure described in any one of claims 1 to 16 or the back contact electrode structure described in any one of claims 17 to 32.

34. The back contact solar cell according to claim 33, characterized in that: The invention also includes conductive materials above the circular edge busbars on both sides of the battery substrate along the first direction and welding strips for interconnecting the battery sheets.

35. The back contact solar cell according to claim 34, characterized in that: When at least part of the bus area solder strip is in contact with the bus point, there is no other conductive material contained in the bus electrode or solder strip at the intermediate interface; at the interface between the circular edge bus point and the solder strip, there is a printed circular conductive material, and its circular diameter is ≥0.3mm and ≤0.8mm.

36. A photovoltaic module, characterized in that: include: A back contact solar cell according to any one of claims 33 to 35; Along the second direction, the welding strip extends from the side with the bus electrode to the other side of the battery cell and is connected to another battery cell; the welding strip at the edge connected to the circular edge bus point extends in the opposite direction to the adjacent bus area welding strip.

37. The photovoltaic assembly according to claim 36, characterized in that: The bus area welding strip is coupled and intersected with the bus electrode, and the intersection length is ≥1 / 7 of the bus electrode length and ≤1 / 2 of the bus electrode length; and / or, the number of common coupling points between the welding strip and the bus point, the collecting electrode, and the bus electrode is ≥1 and ≤4.

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