Solar cell, cell module and photovoltaic system

Abstract

The invention is suitable for the field of photovoltaic technology, and provides a solar cell, a cell assembly and a photovoltaic system, the solar cell comprises a silicon wafer, the silicon wafer comprises a first surface and a second surface which are oppositely arranged, and the first surface comprises a first area; the first passivation contact layer is arranged in the first region; the first passivation layer is arranged on the first passivation contact layer, and a first contact hole is formed in the first passivation layer; the first metal electrode is arranged on the first passivation layer, the length direction of the first metal electrode and the length direction of the first contact hole are arranged in the first direction, the width direction of the first metal electrode and the width direction of the first contact hole are arranged in the second direction, and the first metal electrode is in contact with the first passivation contact layer through the first contact hole; and the width of the first contact hole is greater than that of the first metal electrode. According to the solar cell, the risks of local passivation failure of the passivation layer and overlarge contact resistance of the metal electrode can be reduced, so that good cell conversion efficiency of the solar cell is ensured.

Description

Technical Field

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

[0002] A solar cell is a semiconductor device that converts solar energy into electrical energy. Under sunlight, a photocurrent is generated inside the solar cell, and the electrical energy is output through electrodes. In recent years, solar cell manufacturing technology has continued to advance, production costs have been continuously reduced, and conversion efficiency has been continuously improved. The application of solar cell power generation has become increasingly widespread, and it has become an important energy source for electricity supply.

[0003] In related technologies, when preparing metal electrodes for solar cells using non-burn-through pastes, contact holes are typically created in the passivation layer first. The metal electrode then forms a conductive contact with the doped layer through these contact holes. However, in existing technologies, the width of the metal electrode limits the alignment margin between the metal electrode and the contact hole, and there is an inherent alignment deviation between the metal electrode and the contact hole. To ensure good contact between the metal electrode and the doped layer, the width of the metal electrode needs to be increased; that is, the width of the metal electrode is usually greater than the width of the contact hole, completely covering the contact hole. Because the metal electrode completely covers the contact hole, the passivation layer is in contact with the metal electrode at the edges of the contact hole. Under the catalytic action of the metal electrode (especially silver in the metal electrode), hydrogen elements in the passivation layer tend to agglomerate and combine into hydrogen molecules at the contact point between the passivation layer and the metal electrode. This easily leads to the formation of a porous structure at the contact point, which can cause localized passivation failure of the passivation layer. Furthermore, the porous structure leads to a sharp increase in recombination around the metal electrode, resulting in excessively high contact resistance and thus affecting the cell conversion efficiency. Summary of the Invention

[0004] This invention provides a solar cell that aims to solve the problems of existing solar cells, such as the easy occurrence of local passivation failure of the passivation layer and excessive contact resistance of the metal electrodes, which affect the cell conversion efficiency.

[0005] This invention is implemented by providing a solar cell, comprising: A silicon wafer, the silicon wafer including a first surface and a second surface disposed opposite to each other, the first surface including a first region; A first passivation contact layer is provided in the first region; A first passivation layer is disposed on the first passivation contact layer, and the first passivation layer has a first contact hole; and A first metal electrode is disposed on the first passivation layer. The length direction of the first metal electrode and the first contact hole are both arranged along a first direction, and the width direction of the first metal electrode and the first contact hole are both arranged along a second direction. The first metal electrode contacts the first passivation contact layer through the first contact hole, and the width of the first contact hole is greater than the width of the first metal electrode.

[0006] Preferably, the first contact hole includes a first edge and a second edge disposed opposite to each other along the second direction, the width of the first contact hole is W1, the width of the first metal electrode is W2, the distance between the first edge and the first metal electrode is d1, and the distance between the second edge and the first metal electrode is d2, satisfying (0.05W1+0.05W2)μm<d1+d2<(0.6W1+0.6W2+60)μm.

[0007] Preferably, (0.05W1+0.05W2+5)μm<d1+d2.

[0008] Preferably, (0.05W1+0.05W2+10)μm<d1+d2.

[0009] Preferably, the ratio of the width of the first contact hole to the width of the first metal electrode is greater than or equal to 1.5.

[0010] Preferably, the ratio of the width of the first contact hole to the width of the first metal electrode is greater than or equal to 2.

[0011] Preferably, the width of the first contact hole is greater than 100 micrometers, and the width of the first metal electrode is less than 100 micrometers.

[0012] Preferably, the width of the first contact hole is greater than 100 micrometers, and the width of the first metal electrode is less than 60 micrometers.

[0013] Preferably, the width of the first contact hole is greater than 150 micrometers, and the width of the first metal electrode is less than 30 micrometers.

[0014] Preferably, each of the first metal electrodes is provided with a plurality of first contact holes, and the plurality of first contact holes are arranged at intervals along the first direction.

[0015] Preferably, the plurality of first contact holes are arranged at equal intervals along the first direction.

[0016] Preferably, the distance between two adjacent first contact holes along the first direction is less than 1 mm.

[0017] Preferably, the length of the first contact hole is less than 1 mm.

[0018] Preferably, the line connecting the centers of two adjacent first contact holes along the first direction includes two first line segments located at the two first contact holes and a second line segment not located at the first contact hole, wherein the ratio of the length of the second line segment to the sum of the lengths of the two first line segments is greater than 1 and less than 10.

[0019] Preferably, the dimension of the first contact hole along the first direction is smaller than the dimension of the first contact hole along the second direction.

[0020] Preferably, the first metal electrode includes a barrier layer and a copper layer disposed on the barrier layer, wherein the barrier layer is located between the first passivation contact layer and the copper layer.

[0021] Preferably, the barrier layer comprises one or a combination of at least two of aluminum, nickel, titanium, tungsten, and silver.

[0022] Preferably, the barrier layer comprises at least aluminum.

[0023] Preferably, the first passivation contact layer includes a first tunneling layer and a first doped layer disposed on the first tunneling layer, the first tunneling layer being disposed close to the silicon wafer, and the first metal electrode being in contact with the first doped layer.

[0024] Preferably, the silicon wafer further includes a second region, wherein the first region and the second region are simultaneously disposed on the first surface, or the first region is disposed on the first surface and the second region is disposed on the second surface; the solar cell further includes: A second passivation contact layer is provided in the second region; A second passivation layer is disposed on the second passivation contact layer, and the second passivation layer has a second contact hole; A second metal electrode is disposed on the second passivation layer. The length direction of the second metal electrode and the second contact hole are both arranged along the first direction, and the width direction of the second metal electrode and the second contact hole are both arranged along the second direction. The second metal electrode contacts the second passivation contact layer through the second contact hole, and the width of the second contact hole is greater than the width of the second metal electrode.

[0025] Preferably, the ratio of the width of the second contact hole to the width of the second metal electrode is greater than or equal to 1.5.

[0026] Preferably, the ratio of the width of the second contact hole to the width of the second metal electrode is greater than or equal to 2.

[0027] The present invention also provides a battery assembly including the solar cell described above.

[0028] The present invention also provides a photovoltaic system including the above-described battery module.

[0029] The present invention provides a solar cell in which a first contact hole is formed in a first passivation layer, and a first metal electrode contacts the first passivation contact layer through the first contact hole. Since the width of the first contact hole is greater than the width of the first metal electrode, at least one of the two opposite edges of the first contact hole along its width direction is spaced apart from the first metal electrode. This directly isolates the first metal electrode from a portion of the hydrogen-rich first passivation layer, and the first metal electrode is in complete contact with the first passivation contact layer at the first contact hole location. Because the first metal electrode is directly isolated from the portion of the hydrogen-rich first passivation layer, the contact area between the first metal electrode and the first passivation layer is reduced. This reduces the risk of hydrogen agglomeration and the formation of pores at the edges of the first metal electrode, thereby reducing the risk of local passivation failure of the first passivation layer and excessive contact resistance of the first metal electrode, ensuring good cell conversion efficiency of the solar cell. On the other hand, since the width of the first contact hole is greater than the width of the first metal electrode, a portion of the first passivation contact layer is not covered by the first metal electrode and the first passivation layer, exposing a portion of the first passivation contact layer, which facilitates heat dissipation during solar cell operation and improves the heat dissipation performance of the solar cell.

[0030] Furthermore, since the width of the first contact hole is greater than the width of the first metal electrode, the alignment reference between the first contact hole and the first passivation contact layer is not determined by the width of the first metal electrode, but rather by using the first contact hole, which is wider than the first metal electrode, as the alignment reference. This makes it easier to align the first metal electrode with the first contact hole, ensuring reliable contact between the first metal electrode and the first passivation contact layer. Moreover, the width of the first metal electrode can be reduced, thus reducing the light-shielding area of ​​the first metal electrode and increasing the amount of sunlight entering the silicon wafer, thereby improving the cell conversion efficiency. Attached Figure Description

[0031] Figure 1 A schematic diagram of the first surface of a solar cell provided in an embodiment of the present invention; Figure 2 A schematic diagram of the first surface of a solar cell after the removal of the first metal electrode and the second metal electrode, provided as an embodiment of the present invention; Figure 3 For along Figure 1 A cross-sectional view along the AA direction; Figure 4 for Figure 1 A magnified schematic diagram of part B in the middle; Figure 5 for Figure 2 A magnified schematic diagram of part C in the middle; Figure 6 A cross-sectional schematic diagram of another solar cell provided in an embodiment of the present invention; Figure 7 This is a cross-sectional schematic diagram of the first metal electrode of a solar cell provided in an embodiment of the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the invention, and should not be construed as limiting the invention. Furthermore, it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0033] In the description of this invention, it should be understood that the terms "upper", "lower", "backlit surface", "second surface", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0034] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0035] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0036] Please refer to Figures 1-4 This invention provides a solar cell 100, comprising: Silicon wafer 1, silicon wafer 1 includes a first surface 11 and a second surface 12 disposed opposite to each other, the first surface 11 including a first region 111; The first passivation contact layer 2 is provided in the first region 111; A first passivation layer 3 is disposed on the first passivation contact layer 2, and the first passivation layer 3 has a first contact hole 31; and A first metal electrode 4 is disposed on the first passivation layer 3. The length direction of the first metal electrode 4 and the first contact hole 31 are both arranged along the first direction Y, and the width direction of the first metal electrode 4 and the first contact hole 31 are both arranged along the second direction X. The first metal electrode 4 contacts the first passivation contact layer 2 through the first contact hole 31, and the width W1 of the first contact hole 31 is greater than the width W2 of the first metal electrode 4.

[0037] An embodiment of the present invention provides a solar cell 100 by forming a first contact hole 31 in the first passivation layer 3, that is, a portion of the first metal electrode 4 passes through the first contact hole 31 and contacts the first passivation contact layer 2, so that the first metal electrode 4 contacts the first passivation contact layer 2 through the first contact hole 31. The width W1 of the first contact hole 31 is greater than the width W2 of the first metal electrode 4. Specifically, this can be achieved by reducing the width of the first metal electrode 4, or by reducing the width of the first metal electrode 4 while increasing the width of the first contact hole 31, or by keeping the width of the first metal electrode 4 unchanged and increasing the width of the first contact hole 31, so that the width W1 of the first contact hole 31 is greater than the width W2 of the first metal electrode 4.

[0038] In this embodiment of the invention, since the width W1 of the first contact hole 31 is greater than the width W2 of the first metal electrode 4, at least one of the two opposing edges of the first contact hole 31 along its width direction can be spaced apart from the first metal electrode 4. That is, the first contact hole 31 includes a first edge 311 and a second edge 312 disposed opposite to each other along its width direction, and at least one of the first edge 311 and the second edge 312 of the first contact hole 31 is provided with a gap from the first metal electrode 4. Preferably, both the first edge 311 and the second edge 312 of the first contact hole 31 are spaced apart from the first metal electrode 4. That is, both the first edge 311 and the second edge 312 of the first contact hole 31 are spaced apart from the first metal electrode 4. Thus, the first passivation layer 3 is spaced apart from the first metal electrode 4 in the width direction of the first contact hole 31, and the first passivation layer 3 only contacts the first metal electrode 4 in the length direction of the first contact hole 31. This means that the first metal electrode 4 does not completely cover the first contact hole 31, reducing the contact area between the first metal electrode 4 and the first passivation layer 3. This greatly reduces the pore structure formed by the aggregation of hydrogen elements in the first passivation layer 3 at the edge of the first metal electrode 4, thereby reducing the risk of local passivation failure of the first passivation layer 3 and excessive contact resistance of the first metal electrode 4, and ensuring good cell conversion efficiency of the solar cell 100.

[0039] On the other hand, since the width W1 of the first contact hole 31 is greater than the width W2 of the first metal electrode 4, a portion of the first passivation contact layer 2 is not covered by the first passivation layer 3 and the first metal electrode 4. Thus, a portion of the first passivation contact layer 2 is exposed at the edge of the first metal electrode 4, which is beneficial for heat dissipation during the operation of the solar cell 100 and for improving the heat dissipation performance of the solar cell 100.

[0040] Moreover, in this embodiment of the invention, the alignment reference between the first contact hole 31 and the first passivation contact layer 2 is not determined by the width W2 of the first metal electrode 4, but rather by using the first contact hole 31, which is wider than the first metal electrode 4, as the alignment reference. This makes it easier to align the first metal electrode 4 with the first contact hole 31, ensuring reliable contact between the first metal electrode 4 and the first passivation contact layer 2. In addition, by reducing the width of the first metal electrode 4, or by reducing the width of the first metal electrode 4 while increasing the width of the first contact hole 31, the light-shielding area of ​​the first metal electrode 4 can be reduced. This increases the amount of sunlight entering the silicon wafer 1, thereby improving the cell conversion efficiency. In particular, when the first surface 11 is the back side of the solar cell 100, the light-shielding area of ​​the first metal electrode 4 on the first surface 11 is reduced, which means the light-shielding area on the back side of the solar cell 100 is reduced. This improves the power generation efficiency on the back side of the solar cell 100, thus greatly increasing the bifaciality of the solar cell 100.

[0041] In this embodiment of the invention, due to the presence of the first passivation contact layer 2, the first metal electrode 4 contacts the first passivation contact layer 2. The first metal electrode 4 does not directly contact the silicon wafer 1. Therefore, even if the width W1 of the first contact hole 31 is widened, it will not cause excessive laser damage to the silicon wafer 1. Thus, this embodiment of the invention can reduce the light-shielding area of ​​the first metal electrode 4, and at the same time, it will not increase the recombination loss due to widening the width W1 of the first contact hole 31, which can improve the battery conversion efficiency.

[0042] In this embodiment of the invention, the silicon wafer 1 includes a first surface 11 and a second surface 12 disposed opposite to each other. One of the first surface 11 and the second surface 12 is the back side of the silicon wafer 1, and the other is the front side of the silicon wafer 1. That is, the first region 111 can be located on either the back side or the front side of the silicon wafer 1. Specifically, the back side of the silicon wafer 1 is the backlighting surface of the solar cell 100, that is, the side of the solar cell 100 that faces away from sunlight when it is working, and the front side of the silicon wafer 1 is the light-facing surface of the solar cell 100, that is, the side that faces sunlight when it is working.

[0043] Preferably, the first surface 11 is the back side of the silicon wafer 1, and the second surface 12 is the front side of the silicon wafer 1. When the solar cell 100 is a back-contact solar cell 100, both the positive and negative electrodes of the solar cell 100 are disposed on the first surface 11; that is, in this embodiment of the invention, both the first metal electrode 4 and the second metal electrode 7 are disposed on the first surface 11. The solar cell 100 can also be a double-sided contact solar cell, such as the Topcon solar cell, where the positive and negative electrodes of the solar cell 100 are respectively disposed on the first surface 11 and the second surface 12; that is, in this embodiment of the invention, the first metal electrode 4 is disposed on the first surface 11, and the second metal electrode 7 is disposed on the second surface 12. Figure 3 This illustration shows a solar cell 100 in a back-contact configuration. Figure 6 This illustration shows a solar cell 100 that is a double-sided contact solar cell.

[0044] In this embodiment of the invention, the first metal electrode 4 is specifically a fine grid of the solar cell 100. In some embodiments, the first metal electrode 4 may also be the main grid of the solar cell 100.

[0045] As an embodiment of the present invention, the ratio of the total area of ​​the first metal electrode 4 to the total area of ​​the first surface 11 is less than 10%, that is, the ratio of the sum of the areas of all the first metal electrodes 4 to the total area of ​​the first surface 11 is less than 10%, which makes the light-shielding area of ​​the first metal electrode 4 on the first surface 11 smaller, which can better improve the battery conversion efficiency.

[0046] As an embodiment of the present invention, the ratio of the total area of ​​the first metal electrode 4 to the total area of ​​the first surface 11 is less than 5%, that is, the ratio of the sum of the areas of all the first metal electrodes 4 to the total area of ​​the first surface 11 is less than 5%, which can further reduce the light-shielding area of ​​the first metal electrode 4 on the first surface 11 and further improve the battery conversion efficiency.

[0047] As an embodiment of the present invention, the ratio of the total area of ​​the first metal electrode 4 to the total area of ​​the first surface 11 is less than 3%, that is, the ratio of the sum of the areas of all the first metal electrodes 4 to the total area of ​​the first surface 11 is less than 3%, which can further reduce the light-shielding area of ​​the first metal electrode 4 on the first surface 11 and further improve the battery conversion efficiency.

[0048] As an embodiment of the present invention, the ratio of the total area of ​​the first metal electrode 4 to the total area of ​​the first surface 11 is less than 1%, that is, the ratio of the sum of the areas of all the first metal electrodes 4 to the total area of ​​the first surface 11 is less than 1%, which can further reduce the light-shielding area of ​​the first metal electrode 4 on the first surface 11 and further improve the battery conversion efficiency.

[0049] Please refer to this again. Figure 3 As an embodiment of the present invention, the first passivation contact layer 2 includes a first tunneling layer 21 and a first doped layer 22 disposed on the first tunneling layer 21. The first tunneling layer 21 is disposed close to the silicon wafer 1, and the first metal electrode 4 is in contact with the first doped layer 22.

[0050] In this embodiment, the first tunneling layer 21 is located between the silicon wafer 1 and the first doped layer 22. The first tunneling layer 21 can be a silicon oxide layer, and the first doped layer 22 can be an N-type doped layer or a P-type doped layer. The first contact hole 31 exposes the first doped layer 22, and the first metal electrode 4 partially enters the first contact hole 31 and forms a conductive contact with the first doped layer 22. Since the first tunneling layer 21 and the first doped layer 22 form the first passivation contact layer 2, and the first metal electrode 4 contacts the first doped layer 22, the first metal electrode 4 does not directly contact the silicon wafer 1. When laser-drilled film is used to form the first contact hole 31 on the first passivation layer 3, the laser will not cause laser damage to the silicon wafer 1. Therefore, widening the width W1 of the first contact hole 31 will not increase the recombination loss of the silicon wafer 1, thus improving the battery conversion efficiency. Of course, the structure of the first passivation contact layer 2 is not limited to this. The first passivation contact layer 2 can also be a stacked structure consisting of multiple layers of first tunneling layers 21 and multiple layers of first doped layers 22, with the first metal electrode 4 contacting the outermost first doped layer 22.

[0051] As an embodiment of the present invention, the ratio of the width W1 of the first contact hole 31 to the width W2 of the first metal electrode 4 is greater than or equal to 1.5.

[0052] In this embodiment, the ratio of the width W1 of the first contact hole 31 to the width W2 of the first metal electrode 4 is controlled to be greater than or equal to 1.5. This prevents the ratio of the width W1 of the first contact hole 31 to the width W2 of the first metal electrode 4 from being too small, which would cause the first metal electrode 4 to fail to make reliable contact with the first passivation contact layer 2. This ensures good contact between the first metal electrode 4 and the first passivation contact layer 2, and also facilitates the alignment of the first contact hole 31 and the first metal electrode 4. Furthermore, it also ensures that the first passivation layer 3 maintains a certain distance from the first metal electrode 4 in the width direction of the first contact hole 31, which can reduce the risk of local passivation failure of the first passivation layer 3 and excessive contact resistance of the first metal electrode 4. For example, the ratio of the width W1 of the first contact hole 31 to the width W2 of the first metal electrode 4 can be any value among 1.5, 1.55, 1.6, 1.64, 1.7, 1.76, 1.8, 1.87, 1.9, 1.93, 2.0, 2.25, 2.3, 2.5, 2.8, 2.9, 3.0, 3.2, 3.5, 3.6, 3.9, 4.0, 5.0, 5.5, 6.0, 8.0, and 10.0.

[0053] As an embodiment of the present invention, the ratio of the width W1 of the first contact hole 31 to the width W2 of the first metal electrode 4 is greater than or equal to 2.

[0054] In this embodiment, the ratio of the width W1 of the first contact hole 31 to the width W2 of the first metal electrode 4 is controlled to be greater than or equal to 2, which further increases the difference between the width W1 of the first contact hole 31 and the width W2 of the first metal electrode 4, making it easier to align the first metal electrode 4 with the first contact hole 31, and further ensuring reliable contact between the first metal electrode 4 and the first passivation contact layer 2.

[0055] As an embodiment of the present invention, the ratio of the width W1 of the first contact hole 31 to the width W2 of the first metal electrode 4 is less than or equal to 10.

[0056] In this embodiment, the ratio of the width W1 of the first contact hole 31 to the width W2 of the first metal electrode 4 is controlled to be less than or equal to 10. This avoids the ratio of the width W1 of the first contact hole 31 to the width W2 of the first metal electrode 4 being too large, which would result in an excessively large width W1 of the first contact hole 31. This prevents the laser opening area of ​​the first passivation contact layer 2 from being too large, which would cause excessive recombination loss. It also avoids the need to increase the laser opening time due to an excessively large width W1 of the first contact hole 31, ensuring good laser production capacity and low cost. Furthermore, it also ensures that the first passivation layer 3 maintains a reasonable distance from the first metal electrode 4 in the width direction of the first contact hole 31, which can further reduce the risk of local passivation failure of the first passivation layer 3 and excessive contact resistance of the first metal electrode 4.

[0057] As an embodiment of the present invention, the width W1 of the first contact hole 31 is greater than 100 micrometers, and the width W2 of the first metal electrode 4 is less than 100 micrometers.

[0058] In this embodiment, the width W1 of the first contact hole 31 is controlled to be greater than 100 micrometers and the width W2 of the first metal electrode 4 is less than 100 micrometers, which facilitates the alignment of the first metal electrode 4 with the first contact hole 31 and ensures reliable contact between the first metal electrode 4 and the first passivation contact layer 2. Moreover, the width W2 of the first metal electrode 4 is less than 100 micrometers, which can effectively reduce the light-shielding area of ​​the first metal electrode 4 and improve the battery conversion efficiency.

[0059] For example, the width W1 of the first contact hole 31 is 110 micrometers, and the width W2 of the first metal electrode 4 is 80 micrometers.

[0060] As an embodiment of the present invention, the width W1 of the first contact hole 31 is greater than 100 micrometers, and the width W2 of the first metal electrode 4 is less than 60 micrometers.

[0061] In this embodiment, the width W1 of the first contact hole 31 is controlled to be greater than 100 micrometers, and the width W2 of the first metal electrode 4 is less than 60 micrometers. This further increases the difference between the width W1 of the first contact hole 31 and the width W2 of the first metal electrode 4, facilitating alignment between the first metal electrode 4 and the first contact hole 31 and ensuring reliable contact between the first metal electrode 4 and the first passivation contact layer 2. Furthermore, it further reduces the light-shielding area of ​​the first metal electrode 4, improving battery conversion efficiency. Additionally, it better ensures the spacing between the first passivation layer 3 and the first metal electrode 4 in the width direction, further reducing the risk of local passivation failure of the first passivation layer 3 and excessive contact resistance of the first metal electrode 4. For example, the width W1 of the first contact hole 31 is 120 micrometers, and the width W2 of the first metal electrode 4 is 50 micrometers.

[0062] As an embodiment of the present invention, the width W1 of the first contact hole 31 is greater than 150 micrometers, and the width W2 of the first metal electrode 4 is less than 30 micrometers.

[0063] In this embodiment, the width W1 of the first contact hole 31 is controlled to be greater than 150 micrometers, and the width W2 of the first metal electrode 4 is less than 30 micrometers. This further increases the difference between the width W1 of the first contact hole 31 and the width W2 of the first metal electrode 4, further facilitating the alignment of the first metal electrode 4 with the first contact hole 31 and ensuring reliable contact between the first metal electrode 4 and the first passivation contact layer 2. Furthermore, it further reduces the light-shielding area of ​​the first metal electrode 4, improving battery conversion efficiency. Additionally, it further ensures the spacing between the first passivation layer 3 and the first metal electrode 4 in the width direction, further reducing the risk of local passivation failure of the first passivation layer 3 and excessive contact resistance of the first metal electrode 4. For example, the width W1 of the first contact hole 31 is 160 micrometers, and the width W2 of the first metal electrode 4 is 20 micrometers.

[0064] As an embodiment of the present invention, the first contact hole 31 includes a first edge 311 and a second edge 312 disposed opposite to each other along the second direction X. The width of the first contact hole 31 is W1, the width of the first metal electrode 4 is W2, the distance between the first edge 311 and the first metal electrode 4 is d1, and the distance between the second edge 312 and the first metal electrode 4 is d2, satisfying (0.05W1+0.05W2)μm<d1+d2<(0.6W1+0.6W2+60)μm.

[0065] In this embodiment, (0.05W1 + 0.05W2)μm is controlled to be less than d1 + d2, meaning the sum of d1 and d2 is greater than (0.05W1 + 0.05W2)μm. This avoids the sum of d1 and d2 being too small, meaning the width difference between the first metal electrode 4 and the first contact hole 31 is greater than (0.05W1 + 0.05W2)μm. This ensures sufficient alignment allowance between the first metal electrode 4 and the first contact hole 31, achieving good alignment and making the centers of the first metal electrode 4 and the first contact hole 31 coincide as much as possible. This ensures that the first metal electrode 4 is completely located inside the first contact hole 31, guaranteeing reliable contact between the first metal electrode 4 and the first passivation contact layer 2, thereby improving the contact reliability between the first metal electrode 4 and the first passivation contact layer 2. Furthermore, avoiding the sum of d1 and d2 being too small further ensures the spacing d1 between the first edge 311 and the first metal electrode 4, and the spacing between the second edge 312 and the first passivation contact layer 2. The sum of the spacing d2 of the metal electrodes 4 is sufficiently large, which can further reduce the porosity formed by the aggregation of hydrogen elements in the first passivation layer 3 at the edge of the first metal electrode 4, and further reduce the risk of local passivation failure of the first passivation layer 3 and excessive contact resistance of the first metal electrode 4. On the other hand, controlling d1+d2<(0.6W1+0.6W2+60)μm, that is, controlling the sum of d1 and d2 to be less than (0.6W1+0.6W2+60)μm, avoids the sum of d1 and d2 being too large, which would lead to an excessively large laser opening area, thereby preventing excessive recombination loss of the first passivation contact layer 2. Therefore, the sum of d1 and d2 satisfies the above relationship, which can not only achieve good alignment between the first metal electrode 4 and the first contact hole 31, improving the contact reliability between the first metal electrode 4 and the first passivation contact layer 2, but also avoid the laser opening area being too large, thereby preventing excessive recombination loss of the first passivation contact layer 2, achieving a balance of multiple effects, and further improving battery efficiency.

[0066] In this embodiment, W1, W2, d1, and d2 must satisfy (0.05W1 + 0.05W2) μm < d1 + d2 < (0.6W1 + 0.6W2 + 60) μm. For example, W1 is 120 μm, W2 is 100 μm, and d1 + d2 = 20 μm; or W1 is 150 μm, W2 is 120 μm, and d1 + d2 = 30 μm; or W1 is 170 μm, W2 is 130 μm, and d1 + d2 = 40 μm.

[0067] As an embodiment of the present invention, (0.05W1+0.05W2+5)μm<d1+d2.

[0068] In this embodiment, (0.05W1+0.05W2+5)μm is further controlled to be less than d1+d2, that is, the sum of d1 and d2 is greater than (0.05W1+0.05W2+5)μm. The sum of d1 and d2 is further increased, that is, the width difference between the first metal electrode 4 and the first contact hole 31 needs to be greater than (0.05W1+0.05W2+5)μm. This further facilitates the good alignment of the first metal electrode 4 and the first contact hole 31, and further improves the contact reliability between the first metal electrode 4 and the first passivation contact layer 2. Moreover, the sum of the distance d1 between the first edge 311 and the first metal electrode 4 and the distance d2 between the second edge 312 and the first metal electrode 4 can be further increased. This can further reduce the pore structure formed by the aggregation of hydrogen elements in the first passivation layer 3 at the edge of the first metal electrode 4, and further reduce the risk of local passivation failure of the first passivation layer 3 and excessive contact resistance of the first metal electrode 4.

[0069] In this embodiment, W1, W2, d1, and d2 must satisfy (0.05W1 + 0.05W2 + 5) μm < d1 + d2 < (0.6W1 + 0.6W2 + 60) μm. For example, W1 is 120 μm, W2 is 100 μm, and d1 + d2 = 20 μm; or W1 is 150 μm, W2 is 120 μm, and d1 + d2 = 30 μm; or W1 is 170 μm, W2 is 130 μm, and d1 + d2 = 40 μm.

[0070] As an embodiment of the present invention, (0.05W1+0.05W2+10)μm<d1+d2.

[0071] In this embodiment, (0.05W1+0.05W2+10)μm is further controlled to be less than d1+d2, that is, the sum of d1 and d2 is greater than (0.05W1+0.05W2+10)μm. This further increases the sum of d1 and d2, which in turn further increases the width difference between the first metal electrode 4 and the first contact hole 31. This facilitates better alignment between the first metal electrode 4 and the first contact hole 31, and further improves the contact reliability between the first metal electrode 4 and the first passivation contact layer 2. Moreover, the sum of the distance d1 between the first edge 311 and the first metal electrode 4 and the distance d2 between the second edge 312 and the first metal electrode 4 can be further increased. This can further reduce the pore structure formed by the aggregation of hydrogen elements in the first passivation layer 3 at the edge of the first metal electrode 4, and further reduce the risk of local passivation failure of the first passivation layer 3 and excessive contact resistance of the first metal electrode 4.

[0072] In this embodiment, W1, W2, d1, and d2 must satisfy (0.05W1 + 0.05W2 + 10) μm < d1 + d2 < (0.6W1 + 0.6W2 + 60) μm. For example, W1 is 120 μm, W2 is 80 μm, and d1 + d2 = 40 μm; or W1 is 150 μm, W2 is 100 μm, and d1 + d2 = 50 μm; or W1 is 170 μm, W2 is 120 μm, and d1 + d2 = 50 μm.

[0073] As an embodiment of the present invention, each first metal electrode 4 is provided with a plurality of first contact holes 31, and the plurality of first contact holes 31 are arranged sequentially at intervals along the first direction Y.

[0074] In this embodiment, the specific number of first contact holes 31 provided for each first metal electrode 4 is not limited. Each first metal electrode 4 uses multiple first contact holes 31 to contact the first passivation contact layer 2, ensuring the reliability of the contact between the first metal electrode 4 and the first passivation contact layer 2. Moreover, the multiple first contact holes 31 are arranged sequentially at intervals along the first direction Y. Compared with the first contact holes 31 being arranged continuously, while ensuring the alignment allowance between the first metal electrode 4 and the first contact holes 31, the area of ​​laser opening of the first passivation layer 3 can be reduced, the laser production capacity can be improved, and the damage caused by the laser can be reduced, thereby reducing composite loss.

[0075] As an embodiment of the present invention, a plurality of first contact holes 31 are arranged at equal intervals along the first direction Y.

[0076] In this embodiment, multiple first contact holes 31 are arranged at equal intervals along the first direction Y, so that the lateral transmission resistance of the battery is more uniformly distributed, which is more conducive to the current collection of the first metal electrode 4, and also facilitates the laser opening process of the first passivation layer 3.

[0077] Please refer to the reference. Figure 5 As an embodiment of the present invention, the distance D between two adjacent first contact holes 31 along the first direction Y is less than 1 mm.

[0078] In this embodiment, the distance D between two adjacent first contact holes 31 along the first direction Y is specifically the distance between the centers of two adjacent first contact holes 31 along the first direction Y, and the center of the first contact hole 31 is specifically the center of the circumcircle of the first contact hole 31. By controlling the distance D between two adjacent first contact holes 31 to be less than 1mm, the lateral transmission resistance of the solar cell 100 between two adjacent first contact holes 31 is smaller, which is more conducive to the current collection of the first metal electrode 4.

[0079] Please refer to the reference. Figure 4 As an embodiment of the present invention, the length L1 of the first contact hole 31 is less than 1 mm.

[0080] In this embodiment, the length L1 of the first contact hole 31 is the size of the first contact hole 31 along the first direction Y. Controlling the length L1 of the first contact hole 31 to be less than 1mm can further reduce the lateral transmission resistance of the battery and further facilitate the current collection of the first metal electrode 4.

[0081] Please refer to the reference. Figure 5 As an embodiment of the present invention, the line connecting the centers of two adjacent first contact holes 31 along the first direction Y includes two first line segments F1 located in the two first contact holes 31 and a second line segment F2 not located in the first contact hole 31. The ratio of the length of the second line segment F2 to the sum of the lengths of the two first line segments F1 is greater than 1 and less than 10.

[0082] In this embodiment, the line connecting the centers of two adjacent first contact holes 31 is divided into a laser-etched area and a non-laser-etched area along the first direction Y. The laser-etched area is the area located within the first contact hole 31, and the non-laser-etched area is the area not located within the first contact hole 31. That is, the ratio of the length of the non-laser-etched area to the length of the laser-etched area between the centers of two adjacent first contact holes 31 is greater than 1 and less than 10. It can also be understood that the ratio of the length of the un-etched area to the length of the laser-etched area between the centers of two adjacent first contact holes 31 is greater than 1 and less than 10. Controlling this ratio within a reasonable range can prevent the distance between two adjacent first contact holes 31 from being too small, thus avoiding excessive laser damage due to an excessively large laser-etched area. At the same time, it can also prevent the distance between two adjacent first contact holes 31 from being too large, thereby preventing excessive lateral transmission resistance of the battery and achieving a balance between the two effects.

[0083] As an embodiment of the present invention, the size of the first contact hole 31 along the first direction Y is smaller than the size of the first contact hole 31 along the second direction X.

[0084] In this embodiment, the dimension of the first contact hole 31 along the first direction Y is smaller than the dimension of the first contact hole 31 along the second direction X, that is, the length L1 of the first contact hole 31 is smaller than the width W1 of the first contact hole 31. By setting the length L1 of the first contact hole 31 to be smaller than the width W1 of the first contact hole 31, it is easier to increase the number of first contact holes 31 in the first direction Y, which helps to reduce the spacing between two adjacent first contact holes 31 along the first direction Y, and further reduces the lateral transmission resistance of the battery.

[0085] Please refer to the reference. Figure 7 As an embodiment of the present invention, the first metal electrode 4 includes a barrier layer 41 and a copper layer 42 disposed on the barrier layer 41, wherein the barrier layer 41 is located between the first passivation contact layer 2 and the copper layer 42.

[0086] In this embodiment, the barrier layer 41 of the first metal electrode 4 is in contact with the first doped layer 22. The barrier layer 41 can block the diffusion of the copper layer 42, preventing the copper material in the copper layer 42 from diffusing into the first passivation contact layer 2, thus avoiding affecting the passivation performance of the first passivation contact layer 2. In addition, since the first metal electrode 4 includes the barrier layer 41 and the copper layer 42 disposed on the barrier layer 41, it is convenient to prepare the first metal electrode 4 using non-burn-through paste electroplating. Specifically, the barrier layer 41 can be prepared first by physical vapor deposition, with the barrier layer 41 serving as a seed layer, and then the copper layer 42 can be formed by electroplating on the barrier layer 41.

[0087] As an embodiment of the present invention, the barrier layer 41 includes one or a combination of at least two of aluminum, nickel, titanium, tungsten, and silver.

[0088] In this embodiment, the barrier layer 41 can be one of aluminum, nickel, titanium, tungsten, and silver, or a combination of at least two of aluminum, nickel, titanium, tungsten, and silver. By configuring the barrier layer 41 to include one or a combination of at least two of aluminum, nickel, titanium, tungsten, and silver, the barrier layer 41 can effectively prevent copper material in the copper layer 42 from diffusing into the first passivation contact layer 2, and also facilitates the use of the barrier layer 41 as a seed layer, making it convenient to electroplate the copper layer 42 on the barrier layer 41.

[0089] As an embodiment of the present invention, the barrier layer 41 comprises at least aluminum.

[0090] In this embodiment, since the aluminum in the barrier layer 41 can interduce with the copper in the copper layer 42 to form an intermediate phase, it can better prevent the copper in the copper layer 42 from expanding into the first passivation contact layer 2, thereby further improving the blocking effect of the barrier layer 41.

[0091] Please refer to Figure 3 and Figure 6 As an embodiment of the present invention, the surface of the silicon wafer 1 further includes a second region 112, wherein the first region 111 and the second region 112 are simultaneously disposed on the first surface 11 of the silicon wafer 1, or the first region 111 is disposed on the first surface 11 of the silicon wafer 1, and the second region 112 is disposed on the second surface 12 of the silicon wafer 1; the solar cell 100 further includes: The second passivation contact layer 5 is provided in the second region 112; A second passivation layer 6 is provided on the second passivation contact layer 5, and the second passivation layer 6 has a second contact hole 61. The second metal electrode 7 is disposed on the second passivation layer 6. The length direction of the second metal electrode 7 and the second contact hole 61 are both arranged along the first direction Y, and the width direction of the second metal electrode 7 and the second contact hole 61 are both arranged along the second direction X. The second metal electrode 7 contacts the second passivation contact layer 5 through the second contact hole 61, and the width W3 of the second contact hole 61 is greater than the width W4 of the second metal electrode 7.

[0092] In this embodiment, the first metal electrode 4 and the second metal electrode 7 are respectively a positive electrode and a negative electrode. Both the first metal electrode 4 and the second metal electrode 7 are fine grids of the solar cell 100, and one of the first metal electrode 4 and the second metal electrode 7 is a positive fine grid and the other is a negative fine grid. In some embodiments, one of the first metal electrode 4 and the second metal electrode 7 is a positive main grid and the other is a negative main grid.

[0093] like Figures 1-3 As shown, the solar cell 100 is a back-contact solar cell. The first surface 11 is the back side of the solar cell 100, and the second surface 12 is the front side of the solar cell 100. A first region 111 and a second region 112 are simultaneously disposed on the first surface 11 of the silicon wafer 1. At this time, a first metal electrode 4 and a second metal electrode 7 are simultaneously disposed on the first surface 11 of the silicon wafer 1. There are multiple first regions 111 and multiple second regions 112, which are alternately disposed on the first surface 11 along a second direction X. The first metal electrode 4 and the second metal electrode 7 are also alternately disposed on the first surface 11 along the second direction X. Preferably, an isolation region 113 is provided between the first region 111 and the second region 112 for physical isolation of the first region 111 and the second region 112. Specifically, the isolation region 113 is a trench.

[0094] Please refer to Figure 6 The solar cell 100 is a bifacial contact solar cell. The first region 111 is located on the first surface 11 of the silicon wafer 1, and the second region 112 is located on the second surface 12 of the silicon wafer 1. At this time, the first metal electrode 4 is located on the first surface 11 of the silicon wafer 1, and the second metal electrode 7 is located on the second surface 12 of the silicon wafer 1. The first passivation contact layer 2 can completely cover the first surface 11 of the silicon wafer 1, or the first passivation contact layer 2 can be intermittently disposed on the first surface 11 of the silicon wafer 1. That is, the entire surface of the first surface 11 of the silicon wafer 1 is the first region 111, or a part of the first surface 11 of the silicon wafer 1 is the first region 111. Similarly, the second passivation contact layer 5 can completely cover the second surface 12 of the silicon wafer 1, or the second passivation contact layer 5 can be intermittently disposed on the second surface 12 of the silicon wafer 1. That is, the entire surface of the second surface 12 of the silicon wafer 1 is the second region 112, or a part of the second surface 12 of the silicon wafer 1 is the second region 112. Preferably, the first passivation contact layer 2 is intermittently disposed on the first surface 11 of the silicon wafer 1, and a spacer region 114 is provided between adjacent first passivation contact layers 2. The second passivation contact layer 5 is intermittently disposed on the second surface 12 of the silicon wafer 1, and a spacer region 114 is also provided between adjacent second passivation contact layers 5.

[0095] As an embodiment of the present invention, the second passivation contact layer 5 includes a second tunneling layer 51 and a second doped layer 52 disposed on the second tunneling layer 51. The second tunneling layer 51 is disposed close to the silicon wafer 1, and the second metal electrode 7 is in contact with the second doped layer 52.

[0096] In this embodiment, the second tunneling layer 51 can be a silicon oxide layer, and the second doped layer 52 has the opposite doping type to the first doped layer 22. For example, the first doped layer 22 is an N-type doped layer, and the second doped layer 52 is a P-type doped layer; or, the first doped layer 22 is a P-type doped layer, and the second doped layer 52 is an N-type doped layer. The P-type doped layer is one or a combination of a polycrystalline silicon layer, a microcrystalline silicon layer, or an amorphous silicon layer containing a P-type dopant, and the N-type doped layer is one or a combination of a polycrystalline silicon layer, a microcrystalline silicon layer, or an amorphous silicon layer containing an N-type dopant. The P-type dopant is a dopant of a Group IIIA element in the periodic table, and the N-type dopant is a dopant of a Group VA element in the periodic table. For example, the P-type dopant can be a boron dopant, and the N-type dopant can be a phosphorus dopant. It is understood that the specific doping types of the second doped layer 52 and the first doped layer 22 are not limited; one of the second doped layer 52 and the first doped layer 22 can be an N-type doped layer, and the other can be a P-type doped layer.

[0097] In this embodiment, the shape, size, and number of the second contact hole 61 and the first contact hole 31 can be the same or different. The ratio of the width W3 of the second contact hole 61 to the width W4 of the second metal electrode 7, and the ratio of the width W1 of the first contact hole 31 to the width W2 of the first metal electrode 4 can be the same or different.

[0098] In this embodiment, since a second contact hole 61 is formed in the second passivation layer 6, the second metal electrode 7 contacts the second passivation contact layer 5 through the second contact hole 61, and the width W3 of the second contact hole 61 is greater than the width W4 of the second metal electrode 7. Specifically, this can be achieved by reducing the width of the second metal electrode 7, or by reducing the width of the second metal electrode 7 while increasing the width of the second contact hole 61, or by keeping the width of the second metal electrode 7 unchanged while increasing the width of the second contact hole 61.

[0099] In this embodiment, since the width W3 of the second contact hole 61 is greater than the width W4 of the second metal electrode 7, the second metal electrode 7 and the hydrogen-rich second passivation layer 6 are directly isolated in the width direction of the second metal electrode 7. As a result, the second metal electrode 7 does not completely cover the second contact hole 61, reducing the contact area between the second metal electrode 7 and the second passivation layer 6. This reduces the pore structure formed by the aggregation of hydrogen elements in the second passivation layer 6 at the edge of the second metal electrode 7, thereby reducing the risk of local passivation failure of the second passivation layer 6 and excessive contact resistance of the second metal electrode 7, and ensuring good battery conversion efficiency.

[0100] Furthermore, the alignment reference between the second contact hole 61 and the second passivation contact layer 5 is not determined by the width W4 of the second metal electrode 7, but rather by using the second contact hole 61, which is wider than the second metal electrode 7, as the alignment reference. This makes it easier to align the second metal electrode 7 with the second contact hole 61, ensuring reliable contact between the second metal electrode 7 and the second contact hole 61. Moreover, the width design of the second metal electrode 7 can be reduced, which can reduce the light-shielding area of ​​the second metal electrode 7, thereby increasing the amount of sunlight entering the silicon wafer 1 and improving the cell conversion efficiency.

[0101] In one embodiment of the present invention, when the second metal electrode 7 is located on the first surface 11, the ratio of the total area of ​​the second metal electrode 7 to the total area of ​​the first surface 11 is less than 10%, that is, the ratio of the sum of the areas of all the second metal electrodes 7 to the total area of ​​the first surface 11 is less than 10%. This results in a smaller light-shielding area of ​​the second metal electrode 7 on the second surface 12, which can better improve the battery conversion efficiency. Further, the ratio of the total area of ​​the second metal electrode 7 to the total area of ​​the first surface 11 is less than 5%. Even further, the ratio of the total area of ​​the second metal electrode 7 to the total area of ​​the first surface 11 is less than 3%. Even further, the ratio of the total area of ​​the second metal electrode 7 to the total area of ​​the first surface 11 is less than 1%.

[0102] In another embodiment of the present invention, when the second metal electrode 7 is located on the second surface 12, the ratio of the total area of ​​the second metal electrode 7 to the total area of ​​the second surface 12 is less than 10%, that is, the ratio of the sum of the areas of all the second metal electrodes 7 to the total area of ​​the second surface 12 is less than 10%. This results in a smaller light-shielding area of ​​the second metal electrode 7 on the second surface 12, which can better improve the battery conversion efficiency. Further, the ratio of the total area of ​​the second metal electrode 7 to the total area of ​​the second surface 12 is less than 5%. Even further, the ratio of the total area of ​​the second metal electrode 7 to the total area of ​​the second surface 12 is less than 3%. Even further, the ratio of the total area of ​​the second metal electrode 7 to the total area of ​​the second surface 12 is less than 1%.

[0103] In a preferred embodiment of the present invention, the ratio of the width W3 of the second contact hole 61 to the width W4 of the second metal electrode 7 is greater than or equal to 1.5.

[0104] In this embodiment, the ratio of the width W3 of the second contact hole 61 to the width W4 of the second metal electrode 7 is controlled to be greater than or equal to 1.5, which ensures good contact between the second metal electrode 7 and the second passivation contact layer 5, and also facilitates the alignment of the second contact hole 61 and the second metal electrode 7, reducing the offset between the second contact hole 61 and the second metal electrode 7; moreover, it also ensures that the second passivation layer 6 maintains a certain distance from the second metal electrode 7 in the width direction of the second contact hole 61, which can reduce the risk of local passivation failure of the second passivation layer 6 and excessive contact resistance of the second metal electrode 7.

[0105] In a preferred embodiment of the present invention, the ratio of the width W3 of the second contact hole 61 to the width W4 of the second metal electrode 7 is greater than or equal to 2.

[0106] In this embodiment, the ratio of the width W3 of the second contact hole 61 to the width W4 of the second metal electrode 7 is further controlled to be greater than or equal to 2, which further ensures reliable contact between the second passivation contact layer 5 and the second metal electrode 7, and also facilitates the alignment of the second contact hole 61 and the second metal electrode 7, preventing the center of the second metal electrode 7 and the second contact hole 61 from shifting. Furthermore, it can further increase the spacing between the second passivation layer 6 and the second metal electrode 7 in the width direction of the second contact hole 61, further reducing the risk of local passivation failure of the second passivation layer 6 and excessive contact resistance of the second metal electrode 7.

[0107] In one embodiment of the present invention, the first passivation layer 3 and the second passivation layer 6 are one or a stack of two of the following: silicon nitride layer and silicon oxynitride layer. The provision of the first passivation layer 3 and the second passivation layer 6 can improve the surface passivation effect of the solar cell 100. When the solar cell 100 is a back-contact solar cell, the first passivation layer 3 and the second passivation layer 6 are integrally formed on the first surface 11 of the solar cell 100; when the solar cell 100 is a double-sided contact solar cell, the first passivation layer 3 and the second passivation layer 6 are respectively disposed on the first surface 11 and the second surface 12 of the solar cell 100.

[0108] This invention also provides a battery assembly, which includes the solar cell 100 described in the above embodiments. It should be noted that this battery assembly has the same or similar beneficial effects as the solar cell 100, and the related aspects between the two can be referred to each other; to avoid repetition, they will not be repeated here.

[0109] In this embodiment, multiple solar cells 100 in the battery assembly can be connected in series to form a battery string, thereby realizing the series current collection and output. For example, the battery cells can be connected in series by setting solder strips (busbars, interconnecting strips), conductive backplates, etc.

[0110] It is understood that in such embodiments, the battery assembly may further include a metal frame, a backsheet, photovoltaic glass, and an encapsulating film. The encapsulating film may be filled between the second surface 12 and the first surface 11 of the solar cell 100, the photovoltaic glass, adjacent cells, etc. As a filler, it may be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulating film may be an EVA film or a POE film, and the specific choice can be made according to the actual situation, without limitation.

[0111] Photovoltaic glass can be applied to the encapsulant film on the second surface 12 of the solar cell 100. The photovoltaic glass can be ultra-clear glass, possessing high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, ultra-clear glass can achieve a light transmittance of over 92%, protecting the solar cell 100 while minimizing impact on its efficiency. Simultaneously, the encapsulant film bonds the photovoltaic glass and the solar cell 100 together, providing sealing, insulation, waterproofing, and moisture protection for the solar cell 100.

[0112] The backsheet can be attached to the encapsulant film on the first surface 11 of the solar cell 100. The backsheet provides protection and support for the solar cell 100, and has reliable insulation, water resistance, and aging resistance. Multiple options are available for the backsheet, typically tempered glass, acrylic glass, aluminum alloy TPT composite encapsulant film, etc., and the specific choice depends on the specific circumstances and is not limited here. The backsheet, solar cell 100, encapsulant film, and photovoltaic glass can be mounted on a metal frame. The metal frame serves as the main external support structure for the entire battery module, providing stable support and installation. For example, the battery module can be installed at the desired location using the metal frame.

[0113] This invention also provides a photovoltaic system, which includes the battery module described in the above embodiments. It should be noted that this photovoltaic system has the same or similar beneficial effects as the solar cell 100 described above, and the related aspects between the two can be referred to each other; to avoid repetition, they will not be repeated here.

[0114] In this embodiment, the photovoltaic system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system are not limited to these; that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0115] In the description of this specification, references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0116] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A solar cell, characterized in that, include: A silicon wafer, the silicon wafer including a first surface and a second surface disposed opposite to each other, the first surface including a first region; A first passivation contact layer is provided in the first region; A first passivation layer is disposed on the first passivation contact layer, and the first passivation layer has a first contact hole; and A first metal electrode is disposed on the first passivation layer. The length direction of the first metal electrode and the first contact hole are both arranged along a first direction, and the width direction of the first metal electrode and the first contact hole are both arranged along a second direction. The first metal electrode contacts the first passivation contact layer through the first contact hole, and the width of the first contact hole is greater than the width of the first metal electrode.

2. The solar cell according to claim 1, characterized in that, The first contact hole includes a first edge and a second edge disposed opposite to each other along the second direction. The width of the first contact hole is W1, the width of the first metal electrode is W2, the distance between the first edge and the first metal electrode is d1, and the distance between the second edge and the first metal electrode is d2, satisfying (0.05W1+0.05W2)μm<d1+d2<(0.6W1+0.6W2+60)μm.

3. The solar cell according to claim 2, characterized in that, (0.05W1+0.05W2+5)μm<d1+d2.

4. The solar cell according to claim 2, characterized in that, (0.05W1+0.05W2+10)μm<d1+d2.

5. The solar cell according to claim 1, characterized in that, The ratio of the width of the first contact hole to the width of the first metal electrode is greater than or equal to 1.

5.

6. The solar cell according to claim 1, characterized in that, The ratio of the width of the first contact hole to the width of the first metal electrode is greater than or equal to 2.

7. The solar cell according to claim 1, characterized in that, The width of the first contact hole is greater than 100 micrometers, and the width of the first metal electrode is less than 100 micrometers.

8. The solar cell according to claim 1, characterized in that, The width of the first contact hole is greater than 100 micrometers, and the width of the first metal electrode is less than 60 micrometers.

9. The solar cell according to claim 1, characterized in that, The width of the first contact hole is greater than 150 micrometers, and the width of the first metal electrode is less than 30 micrometers.

10. The solar cell according to claim 1, characterized in that, Each of the first metal electrodes is provided with a plurality of first contact holes, and the plurality of first contact holes are arranged sequentially at intervals along the first direction.

11. The solar cell according to claim 10, characterized in that, Multiple first contact holes are arranged at equal intervals along the first direction.

12. The solar cell according to claim 10, characterized in that, The distance between two adjacent first contact holes along the first direction is less than 1 mm.

13. The solar cell according to claim 1, characterized in that, The length of the first contact hole is less than 1 mm.

14. The solar cell according to claim 1, characterized in that, The line connecting the centers of two adjacent first contact holes along the first direction includes two first line segments located at the two first contact holes and a second line segment not located at the first contact hole. The ratio of the length of the second line segment to the sum of the lengths of the two first line segments is greater than 1 and less than 10.

15. The solar cell according to claim 1, characterized in that, The dimension of the first contact hole along the first direction is smaller than the dimension of the first contact hole along the second direction.

16. The solar cell according to claim 1, characterized in that, The first metal electrode includes a barrier layer and a copper layer disposed on the barrier layer, wherein the barrier layer is located between the first passivation contact layer and the copper layer.

17. The solar cell according to claim 16, characterized in that, The barrier layer comprises one or a combination of at least two of aluminum, nickel, titanium, tungsten, and silver.

18. The solar cell according to claim 15, characterized in that, The barrier layer comprises at least aluminum.

19. The solar cell according to claim 1, characterized in that, The first passivation contact layer includes a first tunneling layer and a first doped layer disposed on the first tunneling layer. The first tunneling layer is disposed close to the silicon wafer, and the first metal electrode is in contact with the first doped layer.

20. The solar cell according to any one of claims 1 to 19, characterized in that, The silicon wafer further includes a second region, wherein the first region and the second region are simultaneously disposed on the first surface, or the first region is disposed on the first surface and the second region is disposed on the second surface; The solar cell also includes: A second passivation contact layer is provided in the second region; A second passivation layer is disposed on the second passivation contact layer, and the second passivation layer has a second contact hole; A second metal electrode is disposed on the second passivation layer. The length direction of the second metal electrode and the second contact hole are both arranged along the first direction, and the width direction of the second metal electrode and the second contact hole are both arranged along the second direction. The second metal electrode contacts the second passivation contact layer through the second contact hole, and the width of the second contact hole is greater than the width of the second metal electrode.

21. The solar cell according to claim 20, characterized in that, The ratio of the width of the second contact hole to the width of the second metal electrode is greater than or equal to 1.

5.

22. The solar cell according to claim 20, characterized in that, The ratio of the width of the second contact hole to the width of the second metal electrode is greater than or equal to 2.

23. A battery assembly, characterized in that, Including the solar cell as described in any one of claims 1 to 22.

24. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 23.

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