Solar cell

Abstract

The utility model relates to a solar cell which comprises a substrate, a protective film layer, a plurality of welding points and a welding strip. The substrate is provided with a backlight surface, a plurality of welding areas are reserved on the backlight surface, at least one welding area is provided with a rough part, and the roughness of any local area of the rough part is higher than that of a local area, with the same area size, of a polished part on the backlight surface. The rough part is arranged in the welding area, and the roughness of any local area of the rough part is higher than that of the local area, with the same area size, of the polished part on the backlight surface, so that the protective film layer covering the rough part correspondingly presents an uneven rough structure; the welding points arranged on the protective film layer are also of an uneven rough structure, so that the binding force between the welding points and the protective film layer can be improved, the binding force between the welding strip and the welding points can be improved, the welding effect can be improved, the tension test can be met, the defects of infirm welding, insufficient welding, welding point falling and the like of the welding points are avoided, and the welding quality is improved. And the battery performance is improved.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and particularly to a solar cell. Background Art

[0002] A solar cell is a device that converts solar light energy into electrical energy. When sunlight irradiates a solar cell, carriers are generated in the solar cell due to the photovoltaic effect. The carriers are divided into holes and electrons. Under the action of the built-in electric field in the solar cell, holes flow to the P region and electrons flow to the N region. When the solar cell is connected to a circuit, an electric current is generated.

[0003] In related technologies, solar cells include but are not limited to back-contact solar cells, heterojunction solar cells, or tunnel oxide passivated contact cells, etc. In this article, a back-contact solar cell is taken as an example for illustration. For the light-receiving surface of the back-contact cell substrate, it is usually set as a textured surface, and the backlight surface of the substrate is set as a polished surface (there may also be some non-polished morphology areas such as textured surfaces). It includes electrode fine grid lines arranged on the backlight surface of the substrate, doped polysilicon provided between the electrode fine grid lines and the backlight surface of the substrate, electrode main grid lines connected to and cross-set with the electrode fine grid lines, a film layer provided between the electrode main grid lines and the backlight surface of the substrate, a plurality of welding points (also called Pad points or electrodes) connected to the electrode main grid lines, and solder tapes welded to the welding points. The carriers collected by the electrode fine grid lines are transmitted to the electrode main grid lines, and the electrode main grid lines output the current to the device outward through the welding points and the solder tapes in sequence.

[0004] In the welding area, the welding points and the solder tapes are generally connected by solder paste. However, during the welding process, it is very easy to cause poor welding and poor welding force, etc., which affect the contact effect between the solder tape and the welding point, and ultimately lead to a reduction in the photoelectric conversion performance of the battery. Summary of the Utility Model

[0005] Based on this, it is necessary to overcome the defects of the prior art and provide a solar cell that can improve the welding effect, avoid defects such as loose welding, virtual welding, and falling off of the welding points at the welding points, thereby improving the battery performance.

[0006] A solar cell, the solar cell comprising:

[0007] A substrate, the substrate is provided with a backlight surface, and a plurality of welding areas are reserved on the backlight surface. At least one of the welding areas is provided with a rough portion, and the roughness of any local area of the rough portion is higher than the roughness of the local area with the same area size of the polished portion on the backlight surface;

[0008] A protective film layer covering each of the welding areas;

[0009] Multiple welding points, all of the welding points are disposed on the protective film layer, and each of the welding points is disposed corresponding to each of the welding areas; and

[0010] A solder ribbon, the welding points are welded and connected to the solder ribbon.

[0011] In one embodiment, the rough part includes at least one or a combination of multiple overlays of pyramids, pits, dot-like protrusions, and linear marks.

[0012] In one embodiment, the local area is a rectangular area, the length of the local area is 5um to 25um, and the width of the local area is 5um to 25um; and / or, the roughness of any of the local areas of the rough part is 0.2um to 2um.

[0013] In one embodiment, the solar cell further includes a passivation layer disposed between the protective film layer and the backlight surface of the substrate.

[0014] In one embodiment, the thickness of the protective film layer is 10nm to 200nm, and the protective film layer includes one or more overlays of silicon nitride, silicon oxide, and silicon oxynitride; the thickness of the passivation layer is 5nm to 100nm, and the passivation layer includes one or a combination of multiple overlays of aluminum oxide, silicon dioxide, silicon nitride, silicon carbide, hafnium oxide, and titanium oxide.

[0015] In one embodiment, the solar cell further includes doped polysilicon and a tunneling layer disposed between the protective film layer and the backlight surface of the substrate, and the doped polysilicon is connected to the backlight surface through the tunneling layer.

[0016] In one embodiment, the thickness of the tunneling layer is 1nm to 3nm; the tunneling layer includes one or a combination of multiple overlays of silicon dioxide, porous silicon oxide, silicon nitride, silicon carbide, and aluminum oxide.

[0017] In one embodiment, the solar cell further includes a fine grid electrode, a main grid electrode, doped polysilicon, and a tunneling layer; the doped polysilicon is connected to the backlight surface through the tunneling layer, the fine grid electrode is connected to a side of the doped polysilicon facing away from the tunneling layer, the main grid electrode is disposed on the protective film layer, the main grid electrode, the fine grid electrode, and the welding points are in the same layer, and the main grid electrode is respectively connected to the fine grid electrode and the welding points.

[0018] In one embodiment, the fine grid electrodes include a first fine grid electrode and a second fine grid electrode, and the polarities of the first fine grid electrode and the second fine grid electrode are opposite to each other; the main grid electrodes include a first main grid electrode and a second main grid electrode, and the polarities of the first main grid electrode and the second main grid electrode are opposite to each other; the doped polysilicon includes a first doped polysilicon and a second doped polysilicon, and the conductivity type of the first doped polysilicon is different from that of the second doped polysilicon; the first fine grid electrode is connected to the first doped polysilicon, and the first fine grid electrode is connected to the first main grid electrode; the second fine grid electrode is connected to the second doped polysilicon, and the second fine grid electrode is connected to the second main grid electrode.

[0019] In one embodiment, the first doped polysilicon and the second doped polysilicon are arranged at intervals in a direction parallel to the backlight surface to form an isolation region, and the protective film layer is also disposed in the isolation region;

[0020] The welding points include a first welding point connected to the first main grid electrode and a second welding point connected to the second main grid electrode. The welding tape includes a first welding tape connected to the first welding point and extending along the length direction of the first main grid electrode, and a second welding tape connected to the second welding point and extending along the length direction of the second main grid electrode;

[0021] A first insulating layer is provided on a region of the first doped polysilicon close to the second main grid electrode, and the protective film layer is also disposed between the first insulating layer and the first doped polysilicon; a second insulating layer is provided on a region of the second doped polysilicon close to the first main grid electrode, and the protective film layer is also disposed between the second insulating layer and the second doped polysilicon.

[0022] In the above solar cell, since the welding area is provided with a rough portion, the roughness of any local area of the rough portion is higher than that of the local area with the same area size of the polished portion on the backlight surface. The protective film layer covering the rough portion correspondingly presents a rough structure with unevenness, and the welding points provided on the protective film layer also present a rough structure with unevenness, so as to improve the bonding force between the welding points and the protective film layer, and improve the bonding force between the welding tape and the welding points, improve the welding effect, avoid defects such as poor welding, virtual welding and falling off of the welding points, and thus improve the battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a connection structure diagram of a welding point and a film layer of a solar cell in the related art.

[0024] Figure 2 It is a structure diagram of a solar cell according to an embodiment of the present application.

[0025] Figure 3 For Figure 2 A partially enlarged structural view of an embodiment at arrow A-A.

[0026] Figure 4 For Figure 2 A partially enlarged structural view of another embodiment at arrow A-A.

[0027] Figure 5 A comparative structural view of a rough part and a planar structure respectively arranged in the welding area.

[0028] Figure 6 A connection structural view of a welding point and a film layer of a solar cell according to an embodiment of the present application.

[0029] 10. Substrate; 11. Backlight surface; 111. Welding area; 112. Rough part; 20. Protective film layer; 30. Welding point; 31. First welding point; 32. Second welding point; 40. Welding tape; 401. Solder paste; 41. First welding tape; 42. Second welding tape; 50. Passivation layer; 60. Doped polysilicon; 61. First doped polysilicon; 62. Second doped polysilicon; 70. Tunneling layer; 80. Fine grid electrode; 81. First fine grid electrode; 82. Second fine grid electrode; 90. Main grid electrode; 91. First main grid electrode; 92. Second main grid electrode; 110. Isolation area; 120. First insulating layer; 130. Second insulating layer. Detailed implementation manners

[0030] In order to make the above objects, features, and advantages of the present application more obvious and understandable, the following will describe the detailed implementation manners of the present application with reference to the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0031] As described in the background art, in the welding process of the related art, it is easy to cause problems such as poor welding and poor welding force, which affect the contact effect between the welding tape and the welding point and reduce the photoelectric conversion performance of the battery. Through research by the inventor, it is found that the reason for this problem is that there are certain line marks or concave-convex structures after etching on the backlight surface of the substrate, but its surface may be relatively smooth in a local range. For example, for a square structure formed by etching, its side length is about 10-20 um, and the inner surface of the square is extremely smooth, and the roughness can be regarded as 0. In this way, the welding area on the backlight surface of the substrate corresponding to the welding point is a planar structure, and a layered structure is formed between the backlight surface of the substrate, the welding point, and the solder paste, which is likely to cause problems between the welding point and the film layer (such as Figure 1At the position indicated by the arrow P1 shown, a gap is generated between the solder ribbon and the welding point, and the adhesion between the film layer and the silicon substrate is also relatively poor. As a result, the adhesion between the solder ribbon and the underlying welding point, between the welding point and the underlying film layer, or between the film layer and the silicon substrate is poor, resulting in a weak bonding force. During the tensile test, the welding point or the outer film layer is easily peeled off, exposing the polysilicon.

[0032] For the above reasons, the present application provides a solar cell that can improve the welding effect, avoid defects such as poor welding, false soldering, and welding point detachment at the welding points, thereby improving the performance of the battery.

[0033] Referring to Figures 2 to 4 , Figure 2 shows a structural diagram of a solar cell according to an embodiment of the present application. Figure 3 And Figure 4 respectively show Figure 2 partial enlarged structural diagrams of two different embodiments at the arrow A-A. A solar cell provided by an embodiment of the present application, the solar cell includes but is not limited to a back contact solar cell, a heterojunction solar cell, or a tunnel oxide passivated contact cell, etc. The light-receiving surface of the substrate 10 is usually set as a textured surface, and the backlight surface 11 of the substrate 10 is set as a polished surface. Specifically, the solar cell includes: a substrate 10, a protective film layer 20, a plurality of welding points 30, and a solder ribbon 40. The substrate 10 is provided with a backlight surface 11, and a plurality of welding areas 111 are reserved on the backlight surface 11. At least one welding area 111 is provided with a rough portion 112, or each welding area 111 is provided with a rough portion 112.

[0034] Among them, the roughness of any local area of the rough portion 112 is higher than that of the local area of the same area size of the polished portion on the backlight surface 11. The polished portion on the backlight surface 11 refers to the relatively smooth polished portion other than the rough portion 112 on the backlight surface 11, and does not include some necessary and unnecessary textured surfaces, steps, burrs, pits, etc. In addition, the protective film layer 20 covers each welding area 111. All the welding points 30 are arranged on the protective film layer 20, and each welding point 30 is arranged corresponding to each welding area 111. The welding point 30 is welded and connected to the solder ribbon 40. Specifically, a solder paste 401 is provided above the welding point 30, and the solder ribbon 40 is welded and fixed to the welding point 30 through the solder paste 401.

[0035] In the above-described solar cell, since the rough portion 112 is provided in the welding area 111, the roughness of any local area of the rough portion 112 is higher than that of the local area of the polished portion on the backlight surface 11 with the same area size. The protective film layer 20 covering the rough portion 112 correspondingly presents a rough structure with unevenness, and the welding point 30 provided on the protective film layer 20 also presents a rough structure with unevenness. Thereby, the bonding force between the welding point 30 and the protective film layer 20 can be improved, and the bonding force between the solder strip 40 and the welding point 30 can be improved. The welding effect can be improved, the tensile test can be satisfied, and defects such as poor welding, virtual soldering, and detachment of the welding point 30 can be avoided, thereby improving the battery performance.

[0036] Specifically, the improvement of the bonding force by setting the rough portion 112 in the welding area 111 is mainly manifested in the following points:

[0037] First of all, the rough portion 112 increases the contact area between the electrode paste and the protective film layer 20. For example, referring to Figure 5 , Figure 5 the left part of Figure 5 shows a rough structure of a pyramid. As shown in the right part of

[0038] Figure 6

[0039]

[0040] In addition, the rough portion 112 and the film layer below the electrode paste bite each other, increasing the ability to resist material pulling. As shown in

[0040] In addition, the rough portion 112 can also improve problems such as warping of the edge part of the electrode paste after sintering, so the bonding force is better.It should be noted that the position corresponding setting of each welding point 30 and each welding area 111 means that the central position of the welding point 30 is aligned with the central position of the welding area 111 along the thickness direction of the substrate 10, or it is also allowed that the central position of the welding point 30 deviates from the central position of the welding area 111 due to manufacturing process errors. As long as it is ensured that the welding point 30 does not exceed the outside of the welding area 111. For example, when the welding point 30 is centered, the outermost side is 0.2 mm away from the outermost side of the welding area 111, then the deviation between the centers of the two is less than 0.2 mm. In this embodiment, the projections of the rough part 112 and the welding point 30 on the backlight surface 11 along the thickness direction of the substrate 10 are both located inside the welding area 111 and will not protrude to the outside of the welding area 111, thereby ensuring the battery performance.

[0041] In addition, in this embodiment, the rough part 112 and the welding point 30 located above it are arranged in a corresponding position, so as to improve the bonding force. In addition, the projected contour shape and size of the rough part 112 on the backlight surface 11 along the thickness direction of the substrate 10 can either be the same as the projected contour shape and size of the welding point 30 on the backlight surface 11 along the thickness direction of the substrate 10, so as to improve the bonding force; or there can be a deviation.

[0042] It should be noted that when there are multiple welding areas 111 all provided with rough parts 112, the roughness, shape, etc. of the rough parts 112 of each welding area 111 can either be the same or different from each other, and can be flexibly adjusted and set according to actual needs. Of course, it is also possible that some welding areas 111 are provided with rough parts 112. For example, for the edge parts with relatively weak bonding force, it is preferably to provide rough parts 112 in the welding areas 111 at the edge parts of the substrate 10, so as to improve the bonding force and prevent the situation that it is easy to cause poor welding, poor welding force, etc. during the welding process due to the relatively weak bonding force at the edge parts, and it cannot meet a certain tensile test, affecting the contact effect between the welding tape 40 and the welding point 30, and reducing the photoelectric conversion performance of the battery; the other part of the welding areas 111 do not need to be provided with rough parts 112, specifically for example, the middle parts with relatively strong bonding force. In addition, it can either be that the rough parts 112 are provided in both welding areas 111 with two different polarities, or the rough parts 112 are provided in the welding areas 111 with one polarity and the rough parts 112 are not provided in the welding areas 111 with the other polarity.

[0043] In some embodiments, the projected shape of the rough part 112 on the backlight surface 11 along the thickness direction of the substrate 10 includes, but is not limited to, various shapes such as circular, rectangular, elliptical, trapezoidal, arranged matrix, etc., and can be flexibly adjusted and set according to actual needs, and will not be limited here.

[0044] In one embodiment, the rough portion 112 includes but is not limited to at least one or more laminated combinations of pyramids, pits, dot-shaped protrusions and line marks, which can be flexibly adjusted and set according to actual needs and are not limited here.

[0045] In some embodiments, the local area includes but is not limited to regular shapes such as rectangular areas, triangular areas, pentagonal areas, circular areas or elliptical areas, and other irregular shapes. In this embodiment, the local area is specifically taken as a rectangular area for example, and the length of the local area is not limited to 5um to 25um, such as 5um, 10um, 15um, 20um or 25um, etc. In addition, the width of the local area includes but is not limited to 5um to 25um, such as 5um, 10um, 15um, 20um or 25um, etc. In addition, the roughness of any local area of the rough portion 112 includes but is not limited to 0.2um to 2um. In this way, on the one hand, the roughness of the rough portion 112 in any local area is large, so that it has better bonding force; on the other hand, the roughness of the rough portion 112 in any local area is not too large to increase the difficulty of manufacturing and cause the overall flatness of the battery to not meet the requirements, that is, it can be convenient for production and manufacturing at the same time.

[0046] In one embodiment, the solar cell further includes a passivation layer 50 disposed between the protection film layer 20 and the backlight surface 11 of the substrate 10 .

[0047] In one embodiment, the thickness of the protective film layer 20 includes but is not limited to 10nm~200nm, and the protective film layer 20 includes one or more stacked layers of silicon nitride, silicon oxide, and silicon oxynitride. In addition, the thickness of the passivation layer 50 includes but is not limited to 5nm~100nm, and the passivation layer 50 includes one or more stacked layers of aluminum oxide, silicon dioxide, silicon nitride, silicon carbide, hafnium oxide, and titanium oxide.

[0048] In some embodiments, the protective film layer 20 or the passivation layer 50 located below the protective film layer 20 may be directly connected to the backlight surface 11 of the substrate 10; or may be indirectly connected to the backlight surface 11 of the substrate 10, for example, doped polysilicon 60 and a tunneling layer 70 are disposed between the protective film layer 20 or the passivation layer 50 and the backlight surface 11 of the substrate 10. In addition, when the fine gate electrode 80 contacts the passivation layer 50, the passivation layer 50 in contact with the fine gate electrode 80 may be corroded away, thereby connecting to the side of the doped polysilicon 60 away from the tunneling layer 70.

[0049] In one embodiment, the solar cell further includes a doped polysilicon 60 and a tunneling layer 70 disposed between the protective film layer 20 and the backlight surface 11 of the substrate 10. The doped polysilicon 60 is connected to the backlight surface 11 through the tunneling layer 70. The portion of the tunneling layer 70 corresponding to the rough portion 112 has an uneven rough structure, and the portion of the doped polysilicon 60 corresponding to the rough portion 112 has an uneven rough structure. Thus, the portion of the protective film layer 20 corresponding to and indirectly disposed on the rough portion 112 through the doped polysilicon 60 has an uneven rough structure.

[0050] In one embodiment, the thickness of the tunneling layer 70 includes but is not limited to 1 nm to 3 nm. In addition, the tunneling layer 70 includes one or more of silicon dioxide, porous silicon oxide, silicon nitride, silicon carbide, and aluminum oxide stacked in combination.

[0051] It should be noted that the doping elements of the doped polysilicon 60 include but are not limited to phosphorus, boron, gallium, etc., and can be flexibly adjusted and set according to actual needs.

[0052] In one embodiment, the solar cell further includes a fine grid electrode 80, a main grid electrode 90, a doped polysilicon 60, and a tunneling layer 70. The doped polysilicon 60 is connected to the backlight surface 11 through the tunneling layer 70. The fine grid electrode 80 is connected to the side of the doped polysilicon 60 facing away from the tunneling layer 70. The main grid electrode 90 is disposed on the protective film layer 20. The main grid electrode 90, the fine grid electrode 80, and the welding point 30 are on the same layer, and the main grid electrode 90 is connected to the fine grid electrode 80 and the welding point 30 respectively. Thus, when the solar cell operates, the fine grid electrode 80 can collect the carriers of the doped polysilicon 60 and transmit them to the main grid electrode 90, and the main grid electrode 90 outputs the current to the device through the welding point 30 and the solder strip 40 in sequence.

[0053] In one embodiment, the fine grid electrode 80 includes a first fine grid electrode 81 and a second fine grid electrode 82, and the polarities of the first fine grid electrode 81 and the second fine grid electrode 82 are opposite. In addition, the main grid electrode 90 includes a first main grid electrode 91 and a second main grid electrode 92, and the polarities of the first main grid electrode 91 and the second main grid electrode 92 are opposite. The doped polysilicon 60 includes a first doped polysilicon 61 and a second doped polysilicon 62, and the conduction types of the first doped polysilicon 61 and the second doped polysilicon 62 are different. The first fine grid electrode 81 is connected to the tunneling layer 70 through the first doped polysilicon 61, and the first fine grid electrode 81 is connected to the first main grid electrode 91. The second fine grid electrode 82 is connected to the tunneling layer 70 through the second doped polysilicon 62, and the second fine grid electrode 82 is connected to the second main grid electrode 92.

[0054] Among them, the valence state of the doping element of the first doped polysilicon 61 is different from that of the doping element of the second doped polysilicon 62. Specifically, when the first doped polysilicon 61 is, for example, N-type doped polysilicon 60, the second doped polysilicon 62 is correspondingly, for example, P-type doped polysilicon 60; conversely, when the first doped polysilicon 61 is correspondingly, for example, P-type doped polysilicon 60, the second doped polysilicon 62 is, for example, N-type doped polysilicon 60.

[0055] In one embodiment, the first doped polysilicon 61 and the second doped polysilicon 62 are spaced apart from each other along a direction parallel to the backlight surface 11 to form an isolation region 110, and the protective film layer 20 is also disposed in the isolation region 110.

[0056] In one embodiment, the welding point 30 includes a first welding point 31 connected to the first main grid electrode 91 and a second welding point 32 connected to the second main grid electrode 92. The welding ribbon 40 includes a first welding ribbon 41 connected to the first welding point 31 and extending along the length direction of the first main grid electrode 91, and a second welding ribbon 42 connected to the second welding point 32 and extending along the length direction of the second main grid electrode 92.

[0057] In one embodiment, a first insulating layer 120 is provided on the region of the first doped polysilicon 61 close to the second main grid electrode 92, and the protective film layer 20 is also disposed between the first insulating layer 120 and the first doped polysilicon 61. A second insulating layer 130 is provided on the region of the second doped polysilicon 62 close to the first main grid electrode 91, and the protective film layer 20 is also disposed between the second insulating layer 130 and the second doped polysilicon 62. In this way, under the protection of the first insulating layer 120, it is possible to avoid the second welding ribbon 42 provided on the second main grid electrode 92 from contacting the first fine grid electrode 81 located on the first doped polysilicon 61 due to position deviation, resulting in a short-circuit defect; similarly, under the protection of the second insulating layer 130, it is possible to avoid the first welding ribbon 41 provided on the first main grid electrode 91 from contacting the second fine grid electrode 82 located on the second doped polysilicon 62 due to position deviation, resulting in a short-circuit defect.

[0058] In the description of the present application, it should be understood that if there appear such terms as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., the orientation or positional relationship indicated by these terms is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0059] In addition, if the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this application, if the term "a plurality of" appears, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0060] In this application, unless otherwise clearly specified and defined, if terms such as "installed", "connected", "joined", "fixed", etc. appear, these terms should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0061] In this application, unless otherwise clearly specified and defined, if there are descriptions such as a first feature being "on" or "under" a second feature, etc., the meaning may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature is at a higher horizontal level than the second feature. The first feature being "under", "below" and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature is at a lower horizontal level than the second feature.

[0062] It should be noted that if an element is referred to as "fixed to" or "disposed on" another element, it may be directly on the other element or there may also be an intermediate element. If an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an intermediate element at the same time. If so, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in this application are only for illustrative purposes and do not represent the only implementation manner.

[0063] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity in description, 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, it should be considered as the scope recorded in this specification.

[0064] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A solar cell, characterized in that, The solar cell comprises: A substrate (10), the substrate (10) being provided with a backlight surface (11), a plurality of welding areas (111) being reserved on the backlight surface (11), at least one of the welding areas (111) being provided with a rough portion (112), the roughness of any local area of the rough portion (112) being higher than the roughness of a local area of the same area size of a polished portion on the backlight surface (11); A protective film layer (20), the protective film layer (20) covering each of the welding areas (111); A plurality of welding points (30), all of the welding points (30) are arranged on the protective film layer (20), and each of the welding points (30) is arranged correspondingly to each of the welding areas (111); and A welding strip (40), wherein the welding point (30) is connected to the welding strip (40) by welding.

2. The solar cell according to claim 1, characterized in that, The rough portion (112) includes at least one or more of pyramids, pits, dot-shaped protrusions and line marks, which are stacked in layers.

3. The solar cell according to claim 1, characterized in that, The local area is a rectangular area, the length of the local area is 5um to 25um, and the width of the local area is 5um to 25um; and / or the roughness of any local area of the rough portion (112) is between 0.2um and 2um.

4. The solar cell according to claim 1, wherein The solar cell further comprises a passivation layer (50) arranged between the protective film layer (20) and the backlight surface (11) of the substrate (10).

5. The solar cell according to claim 4, characterized in that, The thickness of the protective film layer (20) is 10 nm to 200 nm, and the protective film layer (20) comprises one or more stacked layers of silicon nitride, silicon oxide, and silicon oxynitride; the thickness of the passivation layer (50) is 5 nm to 100 nm, and the passivation layer (50) comprises one or more stacked layers of aluminum oxide, silicon dioxide, silicon nitride, silicon carbide, hafnium oxide, and titanium oxide.

6. The solar cell according to claim 1, wherein The solar cell further comprises doped polysilicon (60) and a tunneling layer (70) arranged between the protective film layer (20) and the backlight surface (11) of the substrate (10); the doped polysilicon (60) is connected to the backlight surface (11) via the tunneling layer (70).

7. The solar cell according to claim 6, characterized in that, The thickness of the tunneling layer (70) is 1 nm to 3 nm; the tunneling layer (70) comprises one or more of silicon dioxide, porous silicon oxide, silicon nitride, silicon carbide and aluminum oxide in a stacked combination.

8. The solar cell according to claim 1, wherein, The solar cell further comprises a fine gate electrode (80), a main gate electrode (90), doped polysilicon (60) and a tunneling layer (70); the doped polysilicon (60) is connected to the backlight surface (11) via the tunneling layer (70); the fine gate electrode (80) is connected to a side of the doped polysilicon (60) that is away from the tunneling layer (70); the main gate electrode (90) is arranged on the protective film layer (20); the main gate electrode (90), the fine gate electrode (80) and the welding point (30) are in the same layer, and the main gate electrode (90) is connected to the fine gate electrode (80) and the welding point (30) respectively.

9. The solar cell according to claim 8, characterized in that, The fine grid electrode (80) includes a first fine grid electrode (81) and a second fine grid electrode (82), and the polarities of the first fine grid electrode (81) and the second fine grid electrode (82) are opposite; the main grid electrode (90) includes a first main grid electrode (91) and a second main grid electrode (92), and the polarities of the first main grid electrode (91) and the second main grid electrode (92) are opposite; the doped polysilicon (60) includes a first doped polysilicon (61) and a second doped polysilicon (62), and the conduction type of the first doped polysilicon (61) is different from that of the second doped polysilicon (62); the first fine grid electrode (81) is connected to the first doped polysilicon (61), and the first fine grid electrode (81) is connected to the first main grid electrode (91); the second fine grid electrode (82) is connected to the second doped polysilicon (62), and the second fine grid electrode (82) is connected to the second main grid electrode (92).

10. The solar cell according to claim 9, characterized in that, The first doped polysilicon (61) and the second doped polysilicon (62) are spaced apart from each other in a direction parallel to the backlight surface (11) to form an isolation region (110), and the protective film layer (20) is also disposed in the isolation region (110); The welding point (30) includes a first welding point (31) connected to the first main grid electrode (91) and a second welding point (32) connected to the second main grid electrode (92), and the welding strip (40) includes a first welding strip (41) connected to the first welding point (31) and extending along the length direction of the first main grid electrode (91), and a second welding strip (42) connected to the second welding point (32) and extending along the length direction of the second main grid electrode (92); A first insulating layer (120) is provided on a region of the first doped polysilicon (61) close to the second main grid electrode (92), and the protective film layer (20) is also disposed between the first insulating layer (120) and the first doped polysilicon (61); a second insulating layer (130) is provided on a region of the second doped polysilicon (62) close to the first main grid electrode (91), and the protective film layer (20) is also disposed between the second insulating layer (130) and the second doped polysilicon (62).

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