Solar cells, battery modules and photovoltaic systems

Abstract

The present invention is applicable to the field of photovoltaic technology, and provides a solar cell, a battery assembly and a photovoltaic system. The solar cell includes: a semiconductor substrate and a metal grid line, wherein a groove is provided in the semiconductor substrate, and the surface of the groove is a polished surface; wherein the metal grid line is located in the groove and contacts with multiple surfaces of the groove. In the present invention, different from the method of providing a groove in a passivation layer in the prior art, the solar cell of the embodiment of the present invention is directly grooved in the semiconductor substrate, and the metal grid line is arranged in the groove of the semiconductor substrate. The metal grid line can contact with multiple surfaces of the groove in the semiconductor substrate, and the metal grid line can have multiple surfaces in contact with the semiconductor substrate, that is, the contact area between the metal grid line and the semiconductor substrate can be increased, which is more conducive to the collection of carriers by the solar cell, and the photoelectric conversion efficiency of the solar cell can be improved.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a solar cell, a battery assembly and a photovoltaic system. Background Art

[0002] A solar cell is a device that converts sunlight into electrical energy using the photoelectric effect. It is mainly made of photovoltaic materials (such as silicon) and excites electrons by absorbing photons to form an electric current. The cell includes a front electrode, a photovoltaic layer, and a back electrode, which can generate electricity under sunlight and is widely used in power generation systems and various electronic devices.

[0003] In the prior art, the metal electrodes of solar cells are generally made by single-sided contact with the plane of the semiconductor substrate. However, this is not conducive to carrier collection and absorption and utilization of sunlight, resulting in insufficient photoelectric conversion efficiency of the solar cell.

[0004] Based on this, how to design solar cells to improve photoelectric conversion efficiency has become an urgent problem to be solved. Summary of the invention

[0005] The present invention provides a solar cell, a cell assembly and a photovoltaic system to solve the problem of insufficient photoelectric conversion efficiency of solar cells in the prior art.

[0006] The embodiment of the present invention is implemented as follows: the present invention provides a solar cell, a battery assembly and a photovoltaic system. The solar cell includes: a semiconductor substrate and a metal grid line, wherein a groove is formed in the semiconductor substrate, and the surface of the groove is a polished surface; wherein the metal grid line is located in the groove and contacts with multiple surfaces of the groove.

[0007] The present invention directly performs a groove process on the semiconductor substrate and arranges the metal grid line in the groove of the semiconductor substrate, so that the metal grid line can contact multiple surfaces of the groove in the semiconductor substrate, and the metal grid line can have multiple surfaces in contact with the semiconductor substrate, that is, the contact area between the metal grid line and the semiconductor substrate can be increased, which is more conducive to the collection of carriers by the solar cell, and the photoelectric conversion efficiency of the solar cell can be improved.

[0008] Furthermore, the outer contour of the groove is a quadrilateral or an arc.

[0009] Furthermore, the outer contour of the groove is at least one of an inverted trapezoid, a regular trapezoid, a rectangle, a square, and an arc.

[0010] Furthermore, at least a first dielectric layer, a second dielectric layer, and a doped semiconductor layer are disposed on the surface of the semiconductor substrate.

[0011] Furthermore, the first dielectric layer is one or more of a tunneling oxide layer, an intrinsic silicon carbide layer, and an intrinsic amorphous silicon layer.

[0012] Furthermore, the tunneling oxide layer is composed of one or more layers of a titanium dioxide layer, a zinc oxide layer, a silicon oxide layer, and an aluminum oxide layer.

[0013] The present invention can significantly reduce the recombination of the metal contact area by providing a tunneling oxide layer, while having good contact performance, and can greatly improve the efficiency of the solar cell.

[0014] Furthermore, the second dielectric layer is one or more of an oxide layer, a nitride layer, an oxynitride layer, a carbide layer, and an amorphous silicon layer.

[0015] Furthermore, the second dielectric layer is composed of one or more layers of an aluminum oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon carbide layer, an amorphous silicon layer, and a silicon oxide layer.

[0016] By providing a second dielectric layer, the recombination phenomenon on the battery surface can be significantly reduced, the efficiency of the solar cell can be improved, the defect density on the battery surface can be reduced, and the chance of electrons and holes recombinating on the surface can be greatly reduced, thereby significantly improving the performance of the battery.

[0017] Furthermore, the first dielectric layer is arranged on the surface of the semiconductor substrate, the doped semiconductor layer is arranged on the first dielectric layer, and the second dielectric layer is arranged on the doped semiconductor layer.

[0018] Furthermore, the doped semiconductor layer includes a first doped semiconductor layer and a second doped semiconductor layer. Furthermore, the first doped semiconductor layer and the second doped semiconductor layer are N-type doped polysilicon layers or P-type doped polysilicon layers.

[0019] Furthermore, the depth of the groove is 2 μm to 8 μm.

[0020] Furthermore, the side angle of the groove is 90° to 150°.

[0021] The present invention can optimize the morphology of the metal grid line by reasonably setting the shape and depth of the groove, and the groove can guide the slurry of the metal grid line to flow and deposit more evenly in the groove, so that the shape of the metal grid line finally formed is more regular, and the increase of the resistance of the metal grid line caused by the irregular line shape is avoided.

[0022] Furthermore, the metal grid line is in a rectangular parallelepiped shape. The present invention helps to form a larger contact area in the metal grid line groove by setting the metal grid line in a rectangular parallelepiped shape, so that the metal grid line is better embedded in the groove, thereby enhancing the combination of the metal grid line and the semiconductor substrate, making the contact between the metal grid line and the semiconductor substrate closer, reducing the contact resistance, and helping to improve the current conduction efficiency of the solar cell and the battery efficiency of the solar cell. Moreover, the rectangular parallelepiped-shaped metal grid line can also provide better mechanical support for the solar cell, can resist external pressure and stress during operation, and increase the structural durability of the solar cell. In addition, the rectangular parallelepiped-shaped metal grid line design can reduce the shielding of the groove to light, thereby reducing the shadow effect, improving the overall light absorption capacity of the solar cell, and achieving the effect of improving the photoelectric conversion efficiency of the solar cell.

[0023] Furthermore, the metal gate line is a secondary gate line.

[0024] Furthermore, there is a gap between the metal gate line and the side surface of the groove, and the gap is filled with a conductive material.

[0025] The present invention can provide an additional current channel for the metal grid line by filling the gap between the metal grid line and the groove with a conductive material, reduce the contact resistance between the current passing through the metal grid line and the silicon substrate semiconductor substrate, and improve the current conduction capability, thereby achieving the effect of improving the cell efficiency of the solar cell; and the filled conductive material can effectively collect the carriers generated from the semiconductor substrate, further achieving the improvement of the photoelectric conversion efficiency of the solar cell; in addition, the presence of the conductive material also helps to enhance the overall mechanical strength of the metal grid line, reduce the fragility of the metal grid line during manufacturing and use, and achieve the effect of improving the mechanical stability of the solar cell.

[0026] An embodiment of the present invention further provides a battery assembly, which includes the solar cell as described above.

[0027] An embodiment of the present invention further provides a photovoltaic system, which includes the battery assembly as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1A schematic diagram of a photovoltaic system module provided by an embodiment of the present invention;

[0030] Figure 2 A schematic diagram of a module of a battery assembly provided by an embodiment of the present invention;

[0031] Figure 3 A schematic diagram of the structure of a solar cell provided by an embodiment of the present invention;

[0032] Figure 4 for Figure 3 A schematic diagram of the dimensions of the grooves in the solar cell described in;

[0033] Figure 5 for Figure 3 Schematic diagram of the angle of the groove in the solar cell described in;

[0034] Figure 6 for Figure 3 A schematic diagram of a structure in which a conductive material is provided in the solar cell described in the embodiment;

[0035] Figure 7 for Figure 3 A schematic diagram of the specific structure of the solar cell described in FIG.

[0036] Explanation of main component symbols: 1000, photovoltaic system; 1001, battery assembly; 100, solar cell; 10, semiconductor substrate; 11, P region; 12, N region; 13, gap region; 20, metal grid line; 30, groove; 40, conductive material; 50, first dielectric layer; 60, doped semiconductor layer; 70, second dielectric layer. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0038] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "top", "bottom", "lateral", "longitudinal" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention 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 cannot be understood as a limitation on the present invention.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0040] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0042] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples, and the purpose is not to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use scenarios of other materials.

[0043] See also Figure 1 and Figure 2 The photovoltaic system 1000 in the embodiment of the present invention may include the battery assembly 1001 in the embodiment of the present invention. The battery assembly 1001 in the embodiment of the present invention may include a plurality of battery strings. The battery string may include a plurality of solar cells 100 in the embodiment of the present invention.

[0044] In an embodiment of the present invention, a plurality of solar cells 100 in a battery assembly 1001 may be connected in series in sequence to form a battery string, thereby realizing the series bus output of current. For example, the series connection of battery cells may be realized by setting welding strips (bus bars, interconnecting strips), conductive backplanes, etc.

[0045] It is understandable that in such an embodiment, the battery assembly 1001 may also include a metal frame, a back plate, photovoltaic glass and an adhesive film. The adhesive film may be filled between the front and back of the solar cell 100 and the photovoltaic glass, adjacent cells, etc. As a filler, it may be a transparent colloid with good light transmission and aging resistance. For example, the adhesive film may be an EVA adhesive film or a POE adhesive film, which may be selected according to actual conditions and is not limited here.

[0046] Photovoltaic glass can cover the adhesive film on the front side of the solar cell 100. The photovoltaic glass can be ultra-white glass, which has high light transmittance, high transparency, and excellent physical, mechanical and optical properties. For example, the light transmittance of ultra-white glass can reach more than 92%, which can protect the solar cell 100 without affecting the efficiency of the solar cell 100 as much as possible. At the same time, the adhesive film can bond the photovoltaic glass and the solar cell 100 together, and the presence of the adhesive film can seal and insulate the solar cell 100 and make it waterproof and moisture-proof.

[0047] The backplane can be attached to the adhesive film on the back of the solar cell 100. The backplane can protect and support the solar cell 100 and has reliable insulation, water resistance and aging resistance. There are multiple options for the backplane, which can usually be tempered glass, organic glass, aluminum alloy TPT composite adhesive film, etc. It can be set according to specific circumstances and is not limited here. The whole composed of the backplane, solar cell 100, adhesive film and photovoltaic glass can be set on a metal frame. The metal frame serves as the main external support structure of the entire battery assembly 1001 and can stably support and install the battery assembly 1001. For example, the battery assembly 1001 can be installed at the required location through the metal frame.

[0048] It should be noted that the drawings provided in this application are schematic diagrams, and some elements are not shown in the drawings. The purpose is to clearly describe the technical solution and highlight the key points of the invention. It is not intended to limit the technical solution to not include these unshown elements. In other words, the drawings are only examples and do not limit the specific form of the solar cell 100.

[0049] In order to solve the problem that the contact area between the gate line and the semiconductor substrate (such as the silicon substrate) is small and the photovoltaic conversion efficiency of the battery is low in the prior art. Figures 3 to 7, an embodiment of the present invention provides a solar cell 100, and the solar cell 100 includes: a semiconductor substrate 10 and a metal grid line 20. The substrate refers to a substance that serves as a base layer in the semiconductor manufacturing process, usually a silicon wafer or a thin sheet of other materials. As the basis for carrying chips and electronic devices, the substrate can be regarded as the "foundation" of the solar cell 100. The structure of the substrate varies according to specific applications and needs. The most common substrate material is single crystal silicon (Silicon), and in some embodiments, polycrystalline silicon can also be used as a substrate, usually in the form of silicon (Si). The semiconductor substrate 10 of the silicon wafer usually has a circular or square shape, and its surface is flat. In addition to the semiconductor substrate 10, in other embodiments, other materials can also be used as substrates, such as sapphire (Sapphire), silicon carbide (Silicon Carbide), etc.

[0050] In some embodiments, the solar cell 100 of the present invention may be a back contact solar cell 100, a tunnel oxide passivated contact solar cell 100 (TOPcon), or a double-sided contact solar cell 100. A groove 30 may be provided on one side or two opposite sides of the semiconductor substrate 10.

[0051] A groove 30 is provided in the semiconductor substrate 10. Depending on the type of the solar cell 100, the groove 30 can be provided on one side or two opposite sides of the semiconductor substrate 10. Specifically, the groove 30 can be provided on the front side and / or the back side of the semiconductor substrate 10. The surface of the groove 30 is a polished surface, that is, the surface of the groove 30 is a polished surface that has been polished. A metal grid line 20 is provided in the groove 30, so that the metal grid line 20 is located in the groove 30, and the metal grid line 20 can contact multiple surfaces of the groove 30.

[0052] In the present invention, different from the method of opening a groove 30 in the passivation layer in the prior art, the solar cell 100 of the embodiment of the present invention is directly grooved in the semiconductor substrate 10, and the metal grid line 20 is arranged in the groove 30 of the semiconductor substrate 10. The metal grid line 20 can contact multiple surfaces of the groove 30 in the semiconductor substrate 10, and the metal grid line 20 can have multiple (for example, three) surfaces in contact with the semiconductor substrate 10, that is, the contact area between the metal grid line 20 and the semiconductor substrate 10 can be increased, which is more conducive to the collection of carriers and the absorption and utilization of sunlight by the solar cell 100, so as to improve the photoelectric conversion efficiency of the solar cell 100. The metal grid line 20 collects the current generated by the solar cell 100 under light and introduces it into the external circuit. The electrode of the solar cell 100 is composed of two parts, the main grid line and the auxiliary grid line. The main grid line is directly connected to the external lead of the battery and is a relatively thick part. The auxiliary grid line plays the role of collecting and transmitting current to the main line and is a relatively thin part. It is made into a narrow grid line shape to overcome the resistance of the diffusion layer. In some embodiments, the metal gate line 20 is a secondary gate line.

[0053] Moreover, because the metal grid line 20 is arranged in the groove 30 of the semiconductor substrate 10, the surface area of ​​the metal grid line 20 and the semiconductor substrate 10 can be increased, thereby further increasing the contact efficiency between the metal grid line 20 and the semiconductor substrate 10, and enhancing the light absorption effect of the solar cell 100, thereby improving the photoelectric performance of the solar cell 100.

[0054] In addition, in the present invention, the surface of the groove 30 is also set as a polished surface. By setting the surface of the groove 30 on the semiconductor substrate 10 as a polished surface, the light reflection loss of the solar cell 100 can be effectively reduced, thereby improving the light absorption effect of the solar cell 100 and improving the photoelectric performance of the solar cell 100.

[0055] The polished surface of the groove 30 is smooth, which can reduce the reflection of light on the surface of the battery, so that more sunlight can enter the interior of the solar cell 100 to be absorbed and converted into electrical energy. Because when light hits a rough surface, diffuse reflection occurs, causing part of the light to be reflected back to the outside and cannot be used by the battery, and the polished surface can make the light incident at a closer vertical angle, increasing the light transmittance.

[0056] In some embodiments, the polishing surface of the groove 30 in the present invention may be completely smooth or have a certain degree of roughness (for example, the arithmetic mean roughness (Ra) of the surface of the groove 30 is less than 10 μm. When the surface of the groove 30 has a certain degree of roughness, there may be slight protrusions on the surface of the groove 30. At this time, in order to keep the polishing surface of the groove 30 relatively smooth, the maximum height (Rz) of the protrusions on the surface of the groove 30 may be designed to be less than 10 μm. When the smoothness of the polishing surface of the groove 30 is required to be high, the maximum height (Rz) of the protrusions on the surface of the groove 30 may also be designed to be less than 10 nm, and the present invention does not limit this.

[0057] An atomic force microscope (AFM) or an optical profiler is generally used to measure the surface roughness of the polished surface of the groove 30. The smaller the value of the surface roughness, the smoother the surface.

[0058] In addition, when it is necessary to evaluate the reflectivity of the polished surface of the groove 30, it can be tested by a reflectivity tester. A high-quality polished surface should have a lower reflectivity. Generally speaking, the reflectivity of a well-polished single-crystal silicon solar cell surface in the visible light band can be reduced to less than 10%, thereby improving the utilization rate of light.

[0059] The surface of the groove 30 is designed as a polished surface in order to improve the surface quality of the solar panel and increase the photoelectric conversion efficiency. During the polishing process, the surface of the solar panel is rubbed by a polishing machine using tools such as abrasive liquid and a sponge pad to remove surface unevenness, stains and impurities, making the surface smooth. This can reduce light scattering and reflection, increase light absorption, and thus improve photoelectric conversion efficiency.

[0060] Specifically, the semiconductor substrate 10 may be a P-type doped semiconductor substrate 10 or an N-type doped semiconductor substrate 10. In some embodiments, P-type doping refers to doping with group III elements, including boron, aluminum, gallium, indium, thallium and other elements; N-type doping refers to doping with group V elements, including nitrogen, phosphorus, arsenic, antimony, bismuth and other elements, which are not specifically limited here.

[0061] Of course, for the process of grooving the semiconductor substrate 10 to form the groove 30 in the embodiment of the present invention, specifically, the surface of the semiconductor substrate 10 can be polished first. Polishing the surface of the semiconductor substrate 10 can remove scratches, flaws and unevenness on the surface of the semiconductor substrate 10, thereby reducing the loss of light reflected and scattered on the surface, and improving the absorption rate of light, so as to achieve the effect of reducing the mechanical loss of the solar cell 100.

[0062] After that, the semiconductor substrate 10 after the polishing process is subjected to thermal oxidation treatment. During the thermal oxidation treatment process, the semiconductor substrate 10 reacts with oxygen at high temperature to form a silicon oxide (SiO) layer on the surface of the semiconductor substrate 10. The formed silicon oxide layer can be used as a mask in the subsequent processing process to protect the semiconductor substrate 10 below from etching or other chemical treatments. After that, the position where the groove 30 needs to be formed is laser patterned to form a graphic area of ​​the groove 30 on the surface of the semiconductor substrate 10. Then, the position of the groove 30 after the laser treatment is treated with alkaline etching or acid etching. For example, when using potassium hydroxide or sodium hydroxide to etch the area without the silicon oxide layer, or using nitric acid, hydrofluoric acid and other acids to etch, so as to form the depth of the groove 30. Finally, the groove 30 is polished. Thus, through the above process, a groove 30 for placing the metal gate line 20 can be formed in the semiconductor substrate 10.

[0063] In some embodiments, as an example of a solar cell 100, the cell may be an IBC (Interdigitated back contact) cell. For the specific structure of the solar cell 100, such as Figure 7 As shown, the solar cell 100 further includes a P region 11, an N region 12, and a gap region 13 between the P region 11 and the N region 12. The gap region 13 can be used to isolate the P region 11 and the N region 12 to avoid short circuit. A first dielectric layer 50, a doped semiconductor layer 60, and a second dielectric layer 70 are provided in both the P region and the N region.

[0064] The P region 11 and the N region 12 are different regions of the semiconductor substrate 10 . In some embodiments, the positions of the P region 11 and the N region 12 can be interchanged, and the semiconductor substrate 10 can be either an N-type silicon substrate or a P-type silicon substrate.

[0065] Furthermore, after the semiconductor substrate 10 is grooved to form the groove 30, other structures in the solar cell 100, such as the first dielectric layer 50, the doped semiconductor layer 60 and the second dielectric layer 70, are normally grown on the surface of the semiconductor substrate 10, and finally the metal grid line 20 is set.

[0066] In some embodiments, the first dielectric layer 50 is one or more of a tunneling oxide layer, an intrinsic silicon carbide layer, and an intrinsic amorphous silicon layer. As an example, the first dielectric layer 50 can be a tunneling oxide layer, which is composed of one or more layers of a titanium dioxide layer, a zinc oxide layer, a silicon oxide layer, and an aluminum oxide layer. By providing a tunneling oxide layer, the recombination of the metal contact area can be significantly reduced, and at the same time, good contact performance can be achieved, which can greatly improve the efficiency of the solar cell 100.

[0067] In some embodiments, the second dielectric layer 70 is one or more of an oxide layer, a nitride layer, an oxynitride layer, a carbide layer, and an amorphous silicon layer. As an example, the second dielectric layer 70 may be composed of one or more of an aluminum oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon carbide layer, an amorphous silicon layer, and a silicon oxide layer. By providing the second dielectric layer 70, the recombination phenomenon on the surface of the battery can be significantly reduced, the efficiency of the solar cell 100 can be improved, the surface defect density of the solar cell 100 can be reduced, and the chance of electrons and holes being recombined on the surface can be greatly reduced, thereby significantly improving the performance of the solar cell 100.

[0068] In some embodiments, the doped semiconductor layer 60 includes a first doped semiconductor layer and a second doped semiconductor layer. The first doped semiconductor layer and the second doped semiconductor layer are N-type doped polysilicon layers or P-type doped polysilicon layers. For example, the first doped semiconductor layer is a P-type doped polysilicon layer on the P region 11, and the second doped semiconductor layer is an N-type doped polysilicon layer on the N region 12.

[0069] Furthermore, in the present invention, by providing the groove 30 for placing the metal gate line 20 in the semiconductor substrate 10, the morphology of the metal gate line 20 can also be optimized. Because the design of providing the groove 30 in the semiconductor substrate 10 can guide the process of providing the metal gate line 20, the groove 30 can guide the slurry for forming the metal gate line 20 to flow and deposit in the groove 30 more evenly, so that the shape of the metal gate line 20 finally formed is more regular, and the increase of the resistance of the metal gate line 20 caused by the irregular line shape is avoided.

[0070] The metal grid line 20 collects the current generated by the solar cell 100 under light and introduces it into the external circuit. Specifically, the metal grid line 20 is a secondary grid line. In some embodiments, the metal grid line 20 can be formed by electroplating or printing. When the metal grid line 20 is formed by electroplating, copper can be electroplated. Copper electroplating refers to an electrode preparation process in which metallic copper is deposited on the surface of a base metal by an electrolytic method. It is applied to the metallization link of a cell and can replace the existing screen printing technology with high silver consumption, thereby improving the efficiency of the cell and reducing the cost of using silver paste. Metals such as silver or aluminum can also be electroplated, and the present invention does not limit this. In addition, when the metal grid line 20 is formed by printing, aluminum paste or silver paste can be used, and other metal pastes can also be used for printing.

[0071] In a possible implementation, the metal grid line 20 is in a rectangular parallelepiped shape. The rectangular parallelepiped-shaped metal grid line 20 helps to form a larger contact area in the groove 30 of the metal grid line 20, so that the metal grid line 20 is better embedded in the groove 30. This enhances the combination of the metal grid line 20 and the semiconductor substrate 10, making the contact between the metal grid line 20 and the semiconductor substrate 10 closer, reducing the contact resistance, and helping to improve the current conduction efficiency of the solar cell 100, and improving the cell efficiency of the solar cell 100.

[0072] Moreover, the rectangular parallelepiped metal grid line 20 can also provide better mechanical support for the solar cell 100, can resist external pressure and stress during operation, and increase the structural durability of the solar cell 100. In addition, the rectangular parallelepiped metal grid line 20 design can reduce the blocking of light by the groove 30, thereby reducing the shadow effect, improving the overall light absorption capacity of the solar cell 100, and achieving the effect of improving the photoelectric conversion efficiency of the solar cell 100.

[0073] Furthermore, if Figure 4 and Figure 5 As shown, for the specific structure of the groove 30, in a possible implementation, the outer contour of the groove 30 is a quadrilateral or an arc shape, for example, at least one of an inverted trapezoid, a regular trapezoid, a rectangle, a square, and an arc shape.

[0074] Specifically, the shape of the groove 30 can be specifically set to an inverted trapezoid. For example, it can be an isosceles trapezoid or a non-isosceles trapezoid. Exemplarily, the shape of the groove 30 in the embodiment of the present invention can be designed to be an isosceles trapezoid. By reasonably setting the shape of the inverted trapezoid, the contact area between the metal grid line 20 and the groove 30 can be effectively increased, which is more conducive to the collection of carriers by the solar cell 100, thereby achieving the effect of improving the photoelectric conversion efficiency of the solar cell 100. In addition, the shape of the groove 30 is set to an inverted trapezoid, which can also better enhance the capture of incident light. The edge of the inverted trapezoid can effectively reduce the reflection of light, so that more light can enter the semiconductor substrate 10, thereby achieving the effect of improving the light absorption efficiency of the solar cell 100. The inverted trapezoidal groove 30 can also increase the structural stability of the groove 30 to a certain extent, improve the overall mechanical strength of the solar cell 100, and provide a better adaptability effect for the subsequent metal grid line 20 layout and other structures.

[0075] Further, in a possible implementation manner. Figure 4 As shown, for the specific structure of the groove 30, the upper base X of the inverted trapezoid, the lower base Y of the inverted trapezoid and the height D of the inverted trapezoid can be set to satisfy the following relationship:

[0076] It is worth noting that the above relationship between the upper base X, the lower base Y and the height D of the inverted trapezoid is only a possible implementation. In practice, the upper base X, the lower base Y and the height D of the inverted trapezoid can be set to any length.

[0077] Specifically, for the outer profile of the groove 30, the upper base X of the inverted trapezoidal groove 30, the lower base Y of the inverted trapezoidal groove 30, and the height D of the inverted trapezoidal groove 30 satisfy the following relationship: Therefore, through this relationship, the specific structure of the groove 30 can be effectively determined. These relationships show that under a fixed groove 30 height, the gap between the upper bottom of the groove 30 and the lower bottom of the groove 30 depends on the height of the groove 30 and the constant By using this ratio, the light capture and reflection characteristics of the solar cell 100 can be effectively optimized under specific conditions.

[0078] Further, in a possible implementation manner. Figure 5 As shown, the angle of the side angle C of the groove 30 can be adjusted. A smaller side angle C can increase the incident angle of light, which is beneficial to the reflection and absorption of light by the solar cell 100; a larger side angle C can effectively reduce the shadow effect, and also help reduce the loss of light by the solar cell 100. However, when the side angle of the groove 30 is too small, the edge of the groove 30 may block light from different angles in some cases, resulting in a larger shadow effect; and when the side angle C of the groove 30 is too large, the reflection loss of light will increase, and the mechanical stability of the groove 30 will be reduced.

[0079] Alternatively, if Figure 5 As shown, the angle of the side angle C of the groove 30 can be set to between 90° and 150°. In this way, the effect of increasing the light reflection and absorption of the solar cell 100 while improving the mechanical stability of the groove 30 can be achieved. Preferably, the angle of the side angle C of the groove 30 can be set to 90°, 100°, 110°, 120°, 130°, 145°, 150°, etc. In addition, the side angles C on both sides of the groove 30 can also be set to different angles, for example, set to any two values ​​of 90°, 100°, 110°, 120°, 130°, 145°, 150°, in which case the shape of the groove 30 is an irregular trapezoid. Similarly, the side angles C on both sides of the groove 30 can also be set to the same angle, for example, both are set to 90° or both are set to 100°, and the present invention is not limited to this.

[0080] Furthermore, if Figure 4As shown, for the specific structure of the groove 30, the ratio of the length of the upper base X of the inverted trapezoid to the length of the height D of the inverted trapezoid is 0.5 to 1. When the ratio of the length of the upper base X of the inverted trapezoidal groove 30 to the length of the height D of the inverted trapezoidal groove 30 is 0.5 to 1, the groove 30 can avoid the loss caused by excessive reflection of light while maintaining multiple reflections of light; and controlling the ratio of the length of the upper base X of the inverted trapezoidal groove 30 to the length of the height D of the inverted trapezoidal groove 30 also helps to reduce the blocking of the light source by the groove 30, thereby reducing the shadow effect, and can effectively absorb more light, so as to achieve the effect of improving the photoelectric conversion efficiency of the solar cell 100. Preferably, the ratio of the length of the upper base X of the inverted trapezoid to the length of the height D of the inverted trapezoid can be set to 0.5, 0.7, 0.8, 1.

[0081] Furthermore, if Figure 4 As shown in FIG. 1 , for the specific structure of the groove 30, the depth of the groove 30 is 2 μm to 8 μm. Figure 4 In the figure, the depth of the groove 30 is also represented by D. In the embodiment of the present invention, the depth of the groove 30 can be set to 2μm to 8μm. Within this depth range, the groove 30 can increase the number of light reflections and extend the propagation path of light in the groove 30, thereby improving the light absorption rate. At the same time, the appropriate depth of the groove 30 allows the metal grid line 20 to be embedded deeper, increase the contact area with the semiconductor substrate 10, improve the carrier collection efficiency and reduce the contact resistance, and improve the photoelectric conversion efficiency of the solar cell 100. Preferably, the depth of the groove 30 can be set to 2μm, 3μm, 4μm, 5μm, 8μm.

[0082] Furthermore, if Figure 6 As shown, for the specific arrangement of the metal gate line 20 , there is a gap between the metal gate line 20 and the side surface of the groove 30 , and the gap is filled with a conductive material 40 .

[0083] Specifically, in the embodiment of the present invention, there is a gap between the metal grid line 20 and the groove 30. Specifically, there is a gap between the metal grid line 20 and the side surface of the groove 30, and in the embodiment of the present invention, the gap is filled with a conductive material 40. The conductive material 40 filling the gap between the metal grid line 20 and the groove 30 can provide an additional current channel for the metal grid line 20, reduce the contact resistance between the current passing through the metal grid line 20 and the semiconductor substrate 10, and improve the current conduction ability, so as to achieve the effect of improving the cell efficiency of the solar cell 100. And the filled conductive material 40 can effectively collect the carriers generated from the silicon substrate, further achieving the improvement of the photoelectric conversion efficiency of the solar cell 100. In addition, the presence of the conductive material 40 also helps to enhance the overall mechanical strength of the metal grid line 20, reduce the fragility of the metal grid line 20 during the manufacturing and use of the metal grid line 20, and achieve the effect of improving the mechanical stability of the solar cell 100.

[0084] Specifically, the conductive material 40 may be composed of one or more materials such as silver, copper, aluminum, graphene, indium tin oxide, zinc oxide, and nickel.

[0085] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0086] In addition, the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A solar cell, characterized in that: include: A semiconductor substrate and a metal gate line, wherein a groove is provided in the semiconductor substrate, and a surface of the groove is a polished surface; Wherein, the metal grid line is located in the groove and contacts with multiple surfaces of the groove.

2. The solar cell according to claim 1, characterized in that: The outer contour of the groove is a quadrilateral or an arc.

3. The solar cell according to claim 2, characterized in that: The outer contour of the groove is at least one of an inverted trapezoid, a regular trapezoid, a rectangle, a square, and an arc.

4. The solar cell according to claim 1, characterized in that The surface of the semiconductor substrate is at least provided with a first dielectric layer, a second dielectric layer, and a doped semiconductor layer.

5. The solar cell according to claim 4, characterized in that: The first dielectric layer is one or more of a tunneling oxide layer, an intrinsic silicon carbide layer, and an intrinsic amorphous silicon layer.

6. The solar cell according to claim 5, characterized in that: The tunneling oxide layer is composed of one or more layers of a titanium dioxide layer, a zinc oxide layer, a silicon oxide layer, and an aluminum oxide layer.

7. The solar cell according to claim 4, characterized in that: The second dielectric layer is one or more of an oxide layer, a nitride layer, an oxynitride layer, a carbide layer, and an amorphous silicon layer.

8. The solar cell according to claim 7, characterized in that: The second dielectric layer is composed of one or more layers of an aluminum oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon carbide layer, an amorphous silicon layer, and a silicon oxide layer.

9. The solar cell according to claim 4, characterized in that: The first dielectric layer is disposed on the surface of the semiconductor substrate, the doped semiconductor layer is disposed on the first dielectric layer, and the second dielectric layer is disposed on the doped semiconductor layer.

10. The solar cell according to claim 4, characterized in that: The doped semiconductor layer includes a first doped semiconductor layer and a second doped semiconductor layer.

11. The solar cell according to claim 10, characterized in that The first doped semiconductor layer and the second doped semiconductor layer are N-type doped polysilicon layers or P-type doped polysilicon layers.

12. The solar cell according to claim 1, characterized in that The depth of the groove is 2 μm to 8 μm.

13. The solar cell according to claim 1, characterized in that The side angle of the groove is in a range of 90° to 150°.

14. The solar cell according to claim 1, characterized in that The metal grid line is in a rectangular parallelepiped shape.

15. The solar cell according to claim 1, characterized in that The metal gate line is a secondary gate line.

16. The solar cell according to claim 1, characterized in that There is a gap between the metal gate line and the side surface of the groove, and the gap is filled with a conductive material.

17. A battery assembly, characterized in that: The method comprises a plurality of solar cells according to any one of claims 1 to 16.

18. A photovoltaic system, characterized in that: Comprising the battery assembly as claimed in claim 17.

Images