Back contact solar cell

Abstract

This application provides a back-contact solar cell, including a silicon substrate, a first metal grid line, a second metal grid line, a first passivation layer, a second passivation layer, and a protective layer. The first and second metal grid lines are disposed on the back side of the silicon substrate, and adjacent portions of the first and second metal grid lines are spaced apart to form a protective layer accommodating region. The first passivation layer is disposed on the front side of the silicon substrate, and the second passivation layer is disposed on the back side of the silicon substrate and located within the protective layer accommodating region. The protective layer is disposed on the first passivation layer away from the surface of the silicon substrate, and the orthographic projection of the protective layer on the back side of the silicon substrate is located within the orthographic projection of the protective layer accommodating region on the back side of the silicon substrate. The thickness h1 of the protective layer, the distance h2 between the end of the first metal grid line away from the second passivation layer and the second passivation layer, and the distance h3 between the end of the second metal grid line away from the second passivation layer and the second passivation layer satisfy h1>h2 and h1>h3. With this back-contact solar cell, the metal grid lines on the back side are less likely to scratch the textured surface of the front side after stacking.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a back-contact solar cell. Background Technology

[0002] For conventional bifacial metallized solar cells, a pyramidal textured structure is usually set on the front side, and the height of the metal grid lines on both the front and back sides is higher than the passivation film layer. Therefore, bifacial metallized solar cells can be directly stacked without rubbing against the passivation film layer and causing scratches that would affect the cell efficiency and yield. Direct stacking will also not damage the pyramidal textured structure and reduce the light trapping and passivation effects of the bifacial metallized solar cells.

[0003] However, when back-contact solar cells need to be stacked, the metal grid lines on the back side can scratch the pyramidal textured surface and the passivation film layer on the front side, which in turn adversely affects the efficiency and yield of the cells. Summary of the Invention

[0004] Based on this, this application provides a back-contact solar cell, which aims to solve the technical problem that the back metal electrode causes scratches to the front textured surface and passivation film layer after back-contact solar cell stacking, thereby affecting the cell yield and efficiency.

[0005] The technical solution proposed in this application is as follows:

[0006] According to a first aspect of this application, a back-contact solar cell is provided, comprising a silicon substrate, a first metal grid line, a second metal grid line, a first passivation layer, a second passivation layer, and a protective layer.

[0007] The first metal gate line and the second metal gate line are both disposed on the back side of the silicon substrate, and a protective layer accommodating region is formed between adjacent portions of the first metal gate line and the second metal gate line.

[0008] The first passivation layer is disposed on the front side of the silicon substrate, and the second passivation layer is disposed on the back side of the silicon substrate and located within the protective layer accommodating area;

[0009] The protective layer is disposed on the surface of the first passivation layer away from the silicon substrate, and the orthographic projection of the protective layer on the back side of the silicon substrate is located within the orthographic projection range of the protective layer accommodating area on the back side of the silicon substrate; the thickness of the protective layer is h1; the distance between the end of the first metal gate line away from the second passivation layer and the second passivation layer is h2; the distance between the end of the second metal gate line away from the second passivation layer and the second passivation layer is h3; and satisfying h1>h2, h1>h3.

[0010] In some embodiments, the back-contact solar cell further includes a protective frame disposed on the front side of the silicon substrate, and the protective layer is located within the protective frame; the orthographic projections of all the first metal grid lines and the second metal grid lines on the front side of the silicon substrate are all within the orthographic projection range of the protective frame on the front side of the silicon substrate.

[0011] In some embodiments, the thickness of the protective frame is greater than or equal to the thickness of the protective layer.

[0012] In some embodiments, the back-contact solar cell further includes a third passivation layer disposed on at least a portion of the side surface of the silicon substrate; and when the back-contact solar cell includes the third passivation layer, the back-contact solar cell is rectangular or quasi-rectangular in shape.

[0013] In some embodiments, the width of the protective layer accommodating area is d2; the distance between the protective frame and the edge of the silicon substrate in a first direction is B; the distance between the protective frame and the edge of the silicon substrate in a second direction is C, and satisfies 0.2d2≤B≤10d2, 0.2d2≤C≤8d2; wherein, the first direction is the direction perpendicular to the first metal gate line in the plane containing the front side of the silicon substrate, and the second direction is parallel to the first metal gate line.

[0014] In some embodiments, the materials of the protective layer and the protective frame each independently include one or more of acrylic resin, epoxy resin, and silicone resin.

[0015] In some embodiments, the sum of the projected areas of the protective layer and the protective frame on the front side of the silicon substrate is 0.5% to 3% of the front side area of ​​the silicon substrate.

[0016] In some embodiments, the width of the protective frame is greater than or equal to the width of the protective layer.

[0017] In some embodiments, the width of the protective frame is 30μm to 350μm; and / or, the width of the protective layer is 30μm to 350μm.

[0018] In some embodiments, the width of the protective layer is d1, and the width of the protective layer accommodating area is d2, satisfying 0.02d2. <d1<0.8d2。

[0019] In some implementations, h2 is greater than h3, and h1-h2 = 1μm~30μm.

[0020] In some embodiments, a portion of the protective layer accommodating region has one or more protective layers disposed in the orthographic projection area of ​​the front side of the silicon substrate.

[0021] In some embodiments, the orthographic projection shape of each of the protective layers on the front side of the silicon substrate is any one of the following: continuous straight lines, spaced rectangles, spaced dots, spaced squares, or spaced stars.

[0022] Compared with traditional technologies, this application has at least the following beneficial effects:

[0023] By depositing a protective layer on the surface of the first passivation layer facing away from the silicon substrate, the orthogonal projection of the protective layer onto the back side of the silicon substrate lies within the orthogonal projection range of the protective layer's accommodating region onto the back side of the silicon substrate. Furthermore, the thickness h1 of this protective layer is greater than the distance h2 between the end of the first metal gate line away from the second passivation layer and the second passivation layer, and h1 is greater than the distance h3 between the end of the second metal gate line away from the second passivation layer and the second passivation layer. When multiple back-contact solar cells are stacked vertically, the protective layer on the front side of one solar cell contacts the second passivation layer on the back side of another adjacent back-contact solar cell. Since h1 is greater than the largest of h2 and h3, neither the first nor the second metal gate line on the back side of the back-contact solar cell contacts the first passivation layer on the front side of the adjacent stacked back-contact solar cell. This effectively avoids scratches on the front surface texture and passivation film layer caused by the metal gate lines contacting the front side of the back-contact solar cell, thus preventing a decrease in the yield and efficiency of the back-contact solar cell.

[0024] Furthermore, since a protective layer accommodating region is formed between adjacent portions of the first metal grid line and the second metal grid line, the orthogonal projection of the protective layer on the back side of the silicon substrate is located within the orthogonal projection range of the protective layer accommodating region on the back side of the silicon substrate. When multiple back-contact solar cells are stacked neatly, the protective layer can be staggered from the positions of the first and second metal grid lines, allowing the protective layer to adhere more tightly to the second passivation layer. This helps to prevent passivation gas from diffusing to the center of the cell surface during edge passivation of the back-contact solar cell, reducing the risk of oxidation of the metal grid lines due to contact with reactive gases such as sulfides in the air, and reducing the occurrence of plating abnormalities during edge passivation.

[0025] Furthermore, by setting a protective frame on the front side of the silicon substrate, the protective layer is located within the protective frame, and the orthogonal projections of all the first and second metal grid lines on the front side of the silicon substrate are within the orthogonal projection range of the protective frame on the front side of the silicon substrate. When multiple back-contact solar cells are stacked one on top of the other, the protective frame can enclose the first and second metal grid lines on the back side of the back-contact solar cells, which can better prevent the back-contact solar cells from contacting the edge passivation gas, and help reduce plating abnormalities caused during edge passivation. Attached Figure Description

[0026] To better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments or examples, or the best mode of conduct of these applications as currently understood. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0027] Figure 1 This is a schematic diagram of the structure of a back-contact solar cell according to one embodiment of this application.

[0028] Figure 2 This is a schematic diagram of the structure of a back-contact solar cell stack according to one embodiment of this application.

[0029] Figure 3 This is a schematic diagram showing the positions of the back protective layer of the battery, the first metal grid line, and the second metal grid line after the back contact solar cell is stacked according to one embodiment of this application.

[0030] Figure 4 This is a schematic diagram of the structure of a back-contact solar cell according to another embodiment of this application.

[0031] Figure 5 This is a schematic diagram of the structure of a back-contact solar cell according to another embodiment of this application.

[0032] Figure 6 This is a schematic diagram of various shapes of protective layers on the front side of a back-contact solar cell according to one embodiment of this application.

[0033] Figure 7 This is a schematic diagram showing that, according to one embodiment of this application, the protective layer on the back of the back of the stacked solar cells is arranged at an angle to the electrodes.

[0034] Figure 8 This is a top view of the front of a solar cell with a protective frame according to one embodiment of this application.

[0035] Figure 9 This is a schematic diagram of the structure of a back-contact solar cell with a third passivation layer according to an embodiment of this application.

[0036] Figure 10 This is a schematic diagram of the structure of a two-segment back-contact solar cell according to one embodiment of this application.

[0037] Explanation of reference numerals in the attached figures:

[0038] 10. Back contact solar cell; 11. Silicon substrate; 12. First doped silicon layer; 13. Second doped silicon layer; 14. First metal grid line; 15. Second metal grid line; 16. First passivation layer; 17. Second passivation layer; 18. Protective layer; 181. Protective frame; 19. Third passivation layer; 20. Protective layer accommodating area; X, first direction; Y, second direction. Detailed Implementation

[0039] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0041] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0043] The front side of a back-contact solar cell has a pyramidal textured surface, while the first and second metal grid lines, serving as the positive and negative electrodes respectively, are all located on the back side of the cell. From the printing of the metal grid lines to the string bonding of the cells, there are process steps involving stacking the back-contact solar cells together, cutting and passivating their edges, and / or transferring them. After stacking multiple back-contact solar cells, the protruding metal grid lines on the back side of the cells can scratch the pyramidal textured surface and passivation film layer on the front side of the stacked back-contact solar cells, thus adversely affecting the light absorption efficiency and passivation effect of the front side, consequently impacting the conversion efficiency and production yield of the back-contact solar cells.

[0044] Based on this, please refer to Figure 1 , Figure 2 and Figure 3 One embodiment of this application provides a back contact solar cell 10, which includes a silicon substrate 11, a first doped silicon layer 12, a second doped silicon layer 13, a first metal grid line 14, a second metal grid line 15, a first passivation layer 16, a second passivation layer 17, and a protective layer 18.

[0045] The first doped silicon layer 12 and the second doped silicon layer 13 are both disposed on the back side of the silicon substrate 11, and are spaced apart from each other; the first doped silicon layer 12 and the second doped silicon layer 13 have different doping types. The first metal gate line 14 and the second metal gate line 15 are respectively connected to the first doped silicon layer 12 and the second doped silicon layer 13; and a protective layer accommodating region 20 is formed between adjacent portions of the first metal gate line 14 and the second metal gate line 15. The first passivation layer 16 is disposed on the front side of the silicon substrate 11, and the second passivation layer 17 is disposed on the back side of the silicon substrate 11 and located within the protective layer accommodating region 20; the protective layer 18 is disposed on the surface of the first passivation layer 16 away from the silicon substrate 11; the orthographic projection of the protective layer 18 on the back side of the silicon substrate 11 is located within the orthographic projection range of the protective layer accommodating region 20 on the back side of the silicon substrate 11; the thickness of the protective layer 18 is h1; the distance between the end of the first metal gate line 14 away from the second passivation layer 17 and the second passivation layer 17 is h2; the distance between the end of the second metal gate line 15 away from the second passivation layer 17 and the second passivation layer 17 is h3; and satisfying h1>h2, h1>h3.

[0046] The back-contact solar cell 10 described above in this application has a protective layer 18 disposed on the surface of the first passivation layer 16 away from the front side of the silicon substrate 11. The orthographic projection of the protective layer 18 on the back side of the silicon substrate 11 is located within the orthographic projection range of the protective layer accommodating region 20 on the back side of the silicon substrate 11. The thickness h1 of the protective layer 18 is greater than the distance h2 between the end of the first metal gate line 14 away from the second passivation layer 17 and the second passivation layer 17, and h1 is greater than the distance h3 between the end of the second metal gate line 15 away from the second passivation layer 17 and the second passivation layer 17; that is, h1>max(h2, h3); in other words, h1 is greater than the largest of h2 and h3.

[0047] Thus, when multiple back-contact solar cells 10 are stacked vertically, the protective layer 18 on the front of one back-contact solar cell 10 comes into contact with the second passivation layer 17 on the back of another adjacent back-contact solar cell 10. Since h1 is greater than the largest of h2 and h3, neither the first metal grid line 14 nor the second metal grid line 15 on the back of the back-contact solar cell 10 comes into contact with the first passivation layer 16 on the front of the adjacent back-contact solar cell 10. This effectively prevents scratches on the front pyramid textured surface and passivation film layer caused by physical contact between the metal electrodes and the front of the back-contact solar cell 10, thereby improving the light absorption efficiency, the passivation effect on the front, and the conversion efficiency of the back-contact solar cell 10, and also improving the production yield of the back-contact solar cell 10.

[0048] Furthermore, since a protective layer accommodating region 20 is formed between adjacent portions of the first metal grid line 14 and the second metal grid line 15, the orthographic projection of the protective layer 18 on the back side of the silicon substrate 11 is within the orthographic projection range of the protective layer accommodating region 20 on the back side of the silicon substrate 11. When multiple back-contact solar cells 10 are stacked neatly, the protective layer 18 can be staggered from the positions of the first metal grid line 14 and the second metal grid line 15, allowing the protective layer 18 to adhere more tightly to the second passivation layer 17. This helps to prevent passivation gas from diffusing to the center of the cell surface during edge passivation of the back-contact solar cell 10, reducing the risk of oxidation of the metal grid lines due to contact with reactive gases such as sulfides in the air. In addition, when the back-contact solar cell 10 is multi-sliced ​​(i.e., a square or near-square back-contact solar cell 10 is divided into multiple rectangular back-contact solar cells 10), laser cutting is required, and the edge areas of the silicon wafer cut are passivated. By ensuring that the protective layer 18 and the second passivation layer 17 are tightly bonded, it is also beneficial to reduce the phenomenon of passivation gas flowing around into the interior from the gaps in the bonding during edge passivation, thereby reducing edge passivation abnormalities.

[0049] It should be noted that the first doped silicon layer 12 and the second doped silicon layer 13 have different doping types, meaning that one of the first doped silicon layer 12 and the second doped silicon layer 13 is an N-type doped silicon layer and the other is a P-type doped silicon layer. Specifically, when the first doped silicon layer 12 is an N-type doped silicon layer, the second doped silicon layer 13 is a P-type doped silicon layer; when the first doped silicon layer 12 is a P-type doped silicon layer, the second doped silicon layer 13 is an N-type doped silicon layer.

[0050] In this application, the thickness of the protective layer 18 refers to the distance between the end of the protective layer 18 away from the first passivation layer 16 and the highest peak of the first passivation layer 16. The distance h2 between the end of the first metal gate line 14 away from the second passivation layer 17 and the second passivation layer 17 refers to the distance to the highest peak of the second passivation layer 17; the distance h3 between the end of the second metal gate line 15 away from the second passivation layer 17 and the second passivation layer 17 also refers to the distance to the highest peak of the second passivation layer 17.

[0051] Understandably, the protective layer 18 protects the first passivation layer 16 and the front textured surface, and will not scratch the first passivation layer 16 or the front textured surface when it comes into contact with the front of the back-contact solar cell 10. Specifically, the material of the protective layer 18 should have a certain degree of softness and not damage the first passivation layer 16. In addition, the material of the protective layer 18 is preferably a transparent material to reduce the obstruction of sunlight to the front. The material of the protective layer 18 is also preferably a dryable and high-temperature resistant material to facilitate the construction and molding of the protective layer 18 and to have good temperature resistance.

[0052] In some embodiments, the material of the protective layer 18 includes one or more of acrylic resin, epoxy resin, and silicone resin. That is, the protective layer 18 can be one or more of acrylic resin, epoxy resin, and silicone resin. Specifically, a resin-containing slurry can be applied to the first passivation layer 16 on the front side of the back contact solar cell 10 by means of screen printing or spraying, and then the slurry is heated, dried, and cured to obtain the protective layer 18.

[0053] Please see Figure 1In some embodiments, the distance h2 between the end of the first metal grid line 14 furthest from the second passivation layer 17 and the second passivation layer 17 is greater than the distance h3 between the end of the second metal grid line 15 furthest from the second passivation layer 17 and the second passivation layer 17, and h1-h2=1μm~30μm. That is, the thickness h1 of the protective layer 18 is 1μm~30μm greater than the distance h2 between the end of the first metal grid line 14 furthest from the second passivation layer 17 and the second passivation layer 17. In this way, the problem of scratches on the front surface texture and passivation film layer can be better avoided when the first metal grid line 14 and the second metal grid line 15 on the back side come into contact with the first passivation layer 16 on the front side of the adjacent stacked back contact solar cells 10 when multiple back contact solar cells 10 are stacked.

[0054] Understandably, the difference between h1 and h2 can be, but is not limited to, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 25μm, 28μm, 30μm, and any value within the range formed by any two of the above values.

[0055] Understandably, the width of the protective layer 18 should be smaller than the width of the protective layer receiving area 20 so that the protective layer 18 can be accurately placed within the protective layer receiving area 20 when the batteries are stacked. Please refer to [link / reference]. Figure 1 The relationship between the width d1 of the protective layer 18 and the width d2 of the protective layer accommodating area 20 satisfies: 0.02d2 <d1<0.8d2。

[0056] Please see Figure 1 and Figure 4 In some embodiments, a protective layer accommodating region 20 has one or more protective layers 18 disposed in the orthographic projection area on the front side of the silicon substrate 11. That is, only one protective layer 18 may be disposed in the area on the front side of the silicon substrate 11 opposite to the same protective layer accommodating region 20, or multiple protective layers 18 may be disposed simultaneously. The multiple protective layers 18 may be spaced apart from each other.

[0057] Similarly, please see Figure 1 and Figure 5 Each adjacent protective layer 18 has one or more protective layer receiving regions 20 in the area between its orthographic projection on the back side of the silicon substrate 11. In other words, a protective layer 18 is disposed with a gap of one or more protective layer receiving regions 20. In addition, the spacing between the multiple protective layers 18 on the front side of the silicon substrate 11 may be equal or unequal.

[0058] Please see Figure 6In some embodiments, the orthographic projection shape of each protective layer 18 on the front side of the silicon substrate 11 can be any one of the following: continuous straight line, spaced rectangles, spaced dots, spaced squares, or spaced stars. Different shapes of protective layers 18 can be used depending on the characteristics of different types of back-contact solar cells 10. For example, when the back-contact solar cell 10 is a gridless cell, a continuous straight line protective layer 18 can be used; when the back-contact solar cell 10 is a grid-connected cell, discontinuous protective layers 18 such as spaced dots, spaced squares, or spaced stars can be used.

[0059] Understandably, the shapes of multiple protective layers 18 in the same back-contact solar cell 10 can be the same or different. Additionally, as... Figure 7 As shown, the protective layer 18 can be parallel to the first metal grid line 14 and the second metal grid line 15, or it can form a certain angle with the first metal grid line 14 and the second metal grid line 15. The angle can be greater than 0° to less than or equal to 5°.

[0060] In some embodiments, the first passivation layer 16 is a multilayer structure, including a first alumina layer, a first silicon nitride layer, and / or a first silicon oxynitride layer, such as a stack of the first alumina layer and the first silicon nitride layer, or a stack of the first alumina layer and the first silicon oxynitride layer, or a stack of the first alumina layer and the first silicon nitride layer and the first silicon oxynitride layer. Similarly, the second passivation layer 17 is also a multilayer structure, including a second alumina layer, a first silicon nitride layer, and / or a first silicon oxynitride layer.

[0061] Please see Figure 8 In some embodiments, the back contact solar cell 10 further includes a protective frame 181 disposed on the front side of the silicon substrate 11; all protective layers 18 are located within the protective frame 181, and the orthogonal projections of all first metal grid lines 14 and second metal grid lines 15 on the front side of the silicon substrate 11 are all within the orthogonal projection range of the protective frame 181 on the front side of the silicon substrate 11.

[0062] Thus, by setting a protective frame 181 on the front side of the silicon substrate 11, all protective layers 18 are located within the protective frame 181, and the orthogonal projections of all first metal grid lines 14 and second metal grid lines 15 on the front side of the silicon substrate 11 are all within the orthogonal projection range of the protective frame 181 on the front side of the silicon substrate 11. When multiple back-contact solar cells 10 are stacked vertically, the protective frame 181 can enclose the first metal grid lines 14 and second metal grid lines 15 on the back side of the back-contact solar cell 10. In this way, when using multi-segmented back-contact solar cells 10, the contact oxidation of the metal grid lines with reactive gases such as sulfides in the air can be better reduced during edge passivation, and it is more conducive to reducing plating abnormalities during edge passivation. In addition, it is also better to prevent the back-contact solar cell 10 from contacting the edge passivation gas, which is conducive to reducing plating abnormalities during edge passivation.

[0063] Understandably, the material and preparation method of the protective frame 181 can be the same as those of the protective layer 18. Specifically, the protective frame 181 can be one or more of acrylic resin, epoxy resin, and silicone resin.

[0064] In some embodiments, the sum of the projected areas of the protective layer 18 and the protective frame 181 on the front side of the silicon substrate 11 is 0.5% to 3% of the front side area of ​​the silicon substrate 11. Thus, when multiple back-contact solar cells 10 are stacked vertically, not only can the textured structure and passivation film layer on the front side of the back-contact solar cell 10 be effectively protected from scratches, but the shading of the protective layer 18 and the protective frame 181 on the front side light can also be minimized, maintaining a high light absorption rate on the front side.

[0065] Understandably, the sum of the projected areas of the protective layer 18 and the protective frame 181 on the front side of the silicon substrate 11 can be 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3% of the area on the front side of the silicon substrate 11, or any value within the range formed by any two of the above values.

[0066] In some embodiments, the thickness of the protective frame 181 is greater than or equal to the thickness h1 of the protective layer 18. This ensures that when multiple back-contact solar cells 10 are stacked, the protective frame 181 can be tightly bonded to the second passivation layer 17 on the back side of the back-contact solar cell 10. This further reduces the risk of oxidation of the metal grid lines due to contact with reactive gases such as sulfides in the air, and also reduces plating abnormalities during edge passivation.

[0067] In some embodiments, the width of the protective frame 181 is greater than or equal to the width of the protective layer 18. Since the protective frame 181 and the protective layer 18 are formed by printing and curing an adhesive, and the adhesive has a certain degree of fluidity, the printed adhesive film will expand outwards to form a certain boundary. By setting the width of the protective frame 181 to be greater than or equal to the width of the protective layer 18, it is advantageous to make the thickness of the protective frame 181 greater than or equal to the thickness of the protective layer 18.

[0068] In some specific examples, the width of the protective frame 181 is 30μm to 350μm; the width of the protective layer 18 is 30μm to 350μm. Understandably, the widths of the protective frame 181 and the protective layer 18 can each independently be 30μm, 50μm, 80μm, 100μm, 120μm, 150μm, 180μm, 200μm, 220μm, 250μm, 280μm, 300μm, 320μm, 350μm, or any value within the range formed by any two of the above values.

[0069] Please see Figure 1 and Figure 8 In some embodiments, the width of the protective layer accommodating area 20 is d2; the distance between the protective frame 181 and the edge of the silicon substrate 11 in the first direction X is B; the distance between the protective frame 181 and the edge of the silicon substrate 11 in the second direction Y is C, and satisfies 0.2d2≤B≤10d2, 0.2d2≤C≤8d2; wherein, the first direction X is the direction perpendicular to the first metal gate line 14 in the plane where the front side of the silicon substrate 11 is located, and the second direction Y is parallel to the first metal gate line 14.

[0070] By setting the distances between the protective frame 181 and the edge of the silicon substrate 11 along the first direction X and along the second direction Y within the aforementioned ranges, it is beneficial to better protect the textured structure of the back contact solar cell 10. Understandably, the value of B can be 0.2d², 0.5d², 0.8d², 1d², 1.5d², 2d², 2.5d², 3d², 3.5d², 4d², 4.5d², 5d², 5.5d², 6d², 6.5d², 7d², 7.5d², 8d², 8.5d², 9d², 9.5d², 10d², or any value within the range formed by any two of the above values; the value of C can be 0.2d², 0.5d², 0.8d², 1d², 1.5d², 2d², 2.5d², 3d², 3.5d², 4d², 4.5d², 5d², 5.5d², 6d², 6.5d², 7d², 7.5d², 8d², or any value within the range formed by any two of the above values.

[0071] Among them, such as Figure 1As shown, the distance A between adjacent first metal grid line 14 and second metal grid line 15 refers to the distance between the vertical central axis of the first metal grid line 14 and the vertical central axis of the second metal grid line 15.

[0072] Please see Figure 9 In some embodiments, the back contact solar cell 10 further includes a third passivation layer 19, which is disposed in at least a portion of the side surface of the silicon substrate 11; and when the back contact solar cell 10 includes the third passivation layer 19, the back contact solar cell 10 is rectangular or quasi-rectangular in shape. A rectangle is defined as a shape in which the length of one side is greater than the length of the adjacent side.

[0073] When the back-contact solar cell 10 is a large square back-contact solar cell 10 formed into multiple wafers by laser cutting, the laser-cut area at the edge of the silicon wafer needs to be passivated to reduce dangling bonds and form a third passivation layer 19. This application can effectively reduce edge plating abnormalities when forming the third passivation layer 19 by setting a protective frame 181 on the front side of the back-contact solar cell 10.

[0074] Among them, multiple partitions can be binary partitions (such as...) Figure 10 (as shown), three-part wafers, four-part wafers, etc. The material of the third passivation layer 19 includes silicon oxide and aluminum oxide; specifically, it includes a silicon oxide passivation layer with a thickness of 1nm~2nm and an aluminum oxide passivation layer with a thickness of 20nm~100nm stacked sequentially from the side of the silicon wafer outward.

[0075] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0076] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A back-contact solar cell, characterized in that, It includes a silicon substrate, a first metal gate line, a second metal gate line, a first passivation layer, a second passivation layer, and a protective layer; The first metal gate line and the second metal gate line are both disposed on the back side of the silicon substrate, and a protective layer accommodating region is formed between adjacent portions of the first metal gate line and the second metal gate line. The first passivation layer is disposed on the front side of the silicon substrate, and the second passivation layer is disposed on the back side of the silicon substrate and located within the protective layer accommodating area; The protective layer is disposed on the surface of the first passivation layer away from the silicon substrate, and the orthographic projection of the protective layer on the back side of the silicon substrate is located within the orthographic projection range of the protective layer accommodating region on the back side of the silicon substrate; the thickness of the protective layer is h1; the distance between the end of the first metal gate line away from the second passivation layer and the second passivation layer is h2; the distance between the end of the second metal gate line away from the second passivation layer and the second passivation layer is h3; and satisfying h1>h2, h1>h3; The back-contact solar cell also includes a protective frame, which is disposed on the front side of the silicon substrate, and the protective layer is located within the protective frame; the orthographic projections of all the first metal grid lines and the second metal grid lines on the front side of the silicon substrate are all within the orthographic projection range of the protective frame on the front side of the silicon substrate; when multiple back-contact solar cells are stacked one on top of the other, the protective frame can enclose the first metal grid lines and the second metal grid lines on the back side of the silicon substrate within it; The thickness of the protective frame is greater than or equal to the thickness of the protective layer.

2. The back-contact solar cell according to claim 1, characterized in that, The back-contact solar cell further includes a third passivation layer, which is disposed in at least a portion of the side surface of the silicon substrate; and when the back-contact solar cell includes the third passivation layer, the back-contact solar cell is rectangular or quasi-rectangular in shape.

3. The back-contact solar cell according to claim 1, characterized in that, The width of the protective layer accommodating area is d2; the distance between the protective frame and the edge of the silicon substrate in the first direction is B; the distance between the protective frame and the edge of the silicon substrate in the second direction is C, and satisfying 0.2d2≤B≤10d2, 0.2d2≤C≤8d2; Wherein, the first direction is the direction perpendicular to the first metal gate line in the plane containing the front side of the silicon substrate, and the second direction is parallel to the first metal gate line.

4. The back-contact solar cell according to any one of claims 1 to 3, characterized in that, The materials of the protective layer and the protective frame each independently include one or more of acrylic resin, epoxy resin, and silicone resin.

5. The back-contact solar cell according to any one of claims 1 to 3, characterized in that, The sum of the projected areas of the protective layer and the protective frame on the front side of the silicon substrate is 0.5% to 3% of the front side area of ​​the silicon substrate.

6. The back-contact solar cell according to any one of claims 1 to 3, characterized in that, The width of the protective frame is greater than or equal to the width of the protective layer.

7. The back-contact solar cell according to claim 6, characterized in that, The width of the protective frame is 30μm~350μm; And / or, the width of the protective layer is 30μm~350μm.

8. The back-contact solar cell according to any one of claims 1 to 3, characterized in that, The width of the protective layer is d1, and the width of the accommodating area of ​​the protective layer is d2, satisfying 0.02d2. <d1<0.8d2。 9. The back-contact solar cell according to any one of claims 1 to 3, characterized in that, h2 is greater than h3, and h1-h2 = 1μm~30μm.

10. The back-contact solar cell according to any one of claims 1 to 3, characterized in that, One or more protective layers are disposed in the positive projection area of ​​the front side of the silicon substrate in part of the protective layer accommodating region.

11. The back-contact solar cell according to any one of claims 1 to 3, characterized in that, The orthographic projection shape of each of the protective layers on the front side of the silicon substrate is any one of the following: continuous straight lines, spaced rectangles, spaced dots, spaced squares, or spaced stars.

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