A solar cell, a cell assembly, and a photovoltaic system

Abstract

The utility model is suitable for photovoltaic technical field provides a kind of solar cell, battery component and photovoltaic system, this solar cell includes silicon substrate, and the surface of silicon substrate has several nap structure, and nap structure is columnar, and nap structure diameter is 0.5~3 μm, and aspect ratio >5:1.Light is scattered between nap structure multiple times, and the propagation path of light in silicon substrate is lengthened, thereby increasing the probability of light being absorbed by silicon material.Meanwhile, a resonance mode is excited, causing light of a specific wavelength to form a resonance in the nanowire, enhancing the interaction between light and silicon material. The combined effect of multiple scattering and resonance mode enhancement reduces the reflectivity of light and improves spectral absorption performance.

Description

Technical Field

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

[0002] In the field of solar cell manufacturing, existing technologies primarily employ a pyramidal textured surface design to trap light, thereby maximizing light utilization. This technology, through precise control of the pyramid's size and orientation, can effectively adjust and utilize different wavelengths of light, thus maximizing cell efficiency. Theoretically, this pyramidal textured surface design allows light to undergo multiple reflections and refractions within the textured structure, increasing the light propagation path within the cell and thus improving light absorption efficiency.

[0003] However, existing technologies have significant shortcomings. In actual fabrication, the resulting pyramidal textured surfaces vary considerably in size and height, and some areas exhibit incomplete pyramids. These issues lead to relatively low photon utilization, with a reflectivity of approximately 10%. Due to the irregularity of the pyramidal textured surface, the propagation path of light becomes uncontrollable, and some light rays may escape directly from the cell surface during reflection, failing to be effectively absorbed and utilized. This significantly limits the photoelectric conversion efficiency of solar cells, necessitating the development of new processes and technologies to address these problems. Utility Model Content

[0004] This invention provides a solar cell, a battery module, and a photovoltaic system, aiming to solve the problem that the irregularity of the existing textured surface makes the light path uncontrollable and reduces the photoelectric conversion efficiency of the solar cell.

[0005] This invention is achieved as follows: a solar cell includes a silicon substrate, the surface of which has a plurality of textured structures, the textured structures being columnar, the diameter of which is 0.5 to 3 μm and the aspect ratio is >5:1.

[0006] Optionally, the bottom diameter of the velvet structure is larger than its top diameter.

[0007] Optionally, the diameter of the textured structure decreases as the distance to the silicon substrate surface increases.

[0008] Optionally, the top surface of the velvet structure is a plane.

[0009] Optionally, the textured surface is uniformly distributed on the surface of the silicon substrate.

[0010] Optionally, the height of some of the said velvet structures is 2.5 to 15 μm.

[0011] Optionally, there may be gaps between at least some of the adjacent velvet structures.

[0012] Optionally, the spacing between adjacent velvet structures is 0.5 to 6 μm.

[0013] This invention also provides a battery assembly, including the aforementioned solar cell.

[0014] This utility model also provides a photovoltaic system, including the above-mentioned battery components.

[0015] The beneficial effects achieved by this invention are due to the textured structure on the surface of the silicon substrate. This textured structure is columnar, with a diameter of 0.5–3 μm and an aspect ratio > 5:1. Light is scattered multiple times between the textured structures, extending the light propagation path within the silicon substrate and thus increasing the probability of light absorption by the silicon material. Simultaneously, resonant modes are excited, causing light of specific wavelengths to resonate within the nanowires, enhancing the interaction between light and the silicon material. This combined effect of multiple scattering and resonant mode enhancement reduces light reflectivity and improves spectral absorption performance. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the silicon substrate structure of the solar cell provided by this utility model;

[0017] Figure 2 This is a light path diagram at point A;

[0018] Figure 3 This is another optical path diagram at point A;

[0019] Figure 4 This is a top view schematic diagram of the silicon substrate structure of the solar cell provided by this utility model;

[0020] Figure 5 This is a schematic diagram of a solar cell with a silicon substrate structure containing the solar cell provided by this invention.

[0021] Explanation of reference numerals in the attached figures:

[0022] 110. Silicon substrate; 111. Textured surface; 120. First region; 130. Second region; 140. Spacing region. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this utility model and are not intended to limit this utility model.

[0024] In the description of this utility model, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0025] 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 one or more of the stated features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; 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. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0027] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0028] The following disclosure provides numerous different embodiments or examples for implementing various structures of the present invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0029] This invention involves creating a textured structure on the surface of a silicon substrate. The textured structure is columnar, with a diameter of 0.5–3 μm and an aspect ratio > 5:1. Light is repeatedly scattered between the textured structures, lengthening the light propagation path within the silicon substrate and increasing the probability of light absorption by the silicon material. Simultaneously, resonant modes are excited, causing light of specific wavelengths to resonate within the nanowires, enhancing the interaction between light and the silicon material. This combined effect of multiple scattering and resonant mode enhancement reduces light reflectivity and improves spectral absorption performance.

[0030] Example 1

[0031] like Figure 1 As shown, this embodiment provides a solar cell, including a silicon substrate 110. The surface of the silicon substrate 110 has a plurality of textured structures 111. The textured structures 111 are columnar, with a diameter of 0.5 to 3 μm and an aspect ratio of >5:1.

[0032] The silicon substrate 110 has two main surfaces: a light-facing surface and a back-lighting surface. The light-facing surface directly faces sunlight, while the back-lighting surface is on the opposite side. The two surfaces are arranged opposite each other. Several columnar textured structures 111 are distributed on the surface of the silicon substrate 110. Specifically, the textured structures 111 can be arranged on the light-facing surface of the silicon substrate 110, or on the back-lighting surface of the silicon substrate 110, or simultaneously on both the light-facing and back-lighting surfaces; no limitation is made here. The textured structures 111 are columnar, that is, the textured structures 111 are significantly elongated in the direction perpendicular to the surface of the silicon substrate 110, and the cross-sectional shape of the textured structures 111 in the direction perpendicular to the surface of the silicon substrate 110 is rectangular or approximately rectangular (such as trapezoidal, other approximately rectangular quadrilaterals).

[0033] The velvet structure 111 consists of several columnar structures, which can be approximated as cylinders (in reality, they may not be perfectly standard cylinders, but they are treated as approximations when describing dimensions). The diameter is the length of a line segment passing through the center of the cylinder's cross-section, with both ends on the cylinder's circumference. For a single columnar structure, the diameter is used to measure its thickness.

[0034] The diameter of the columnar structures is typically between 0.5 and 3 μm. Specifically, the diameter can be 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm, or other values ​​between 0.5 and 3 μm, without limitation. Within this size range, it is necessary to effectively achieve functions such as light trapping and spectral absorption. If the diameter is too small, it may not be able to form effective multiple scattering and resonant mode enhancement effects; if the diameter is too large, it will reduce the number of columnar structures per unit area, affecting the propagation and absorption efficiency of light within the structure. At the same time, this diameter range is conducive to exciting resonant modes, resonating with light of specific wavelengths, enhancing the interaction between light and silicon materials, especially improving the absorption of near-infrared light (1000-1200 nm), reducing reflectivity, and giving the entire textured structure 111 super-strong spectral absorption performance.

[0035] The aspect ratio of the velvet structure 111 is greater than 5:1, meaning the ratio of the column's height to its width (diameter) is greater than 5. Understandably, the height of the velvet structure 111 is the vertical distance from its top to its bottom. A larger aspect ratio means the columns are relatively slender, a structural feature that allows for more light scattering between the columns. When light enters the columnar structure area, the appropriately sized columns allow the light to be continuously reflected and refracted within it, such as... Figure 2 and Figure 3 As shown, the propagation path of light in the silicon substrate 110 is extended, thereby increasing the probability of light being absorbed by the silicon material, achieving efficient light trapping, and improving long-wavelength absorption efficiency.

[0036] Specifically, the textured structure 111 can be achieved through metal-assisted chemical etching (MACE). The process steps can be as follows: a prepared silver nitrate solution is added dropwise to a reaction vessel, causing silver ions to be reduced on the surface of the silicon substrate 110 to form silver nanoparticles (Ag NPs). As the reaction proceeds, the Ag NPs will sink and guide the etching direction, forming micron-sized pillars (i.e., pillar-shaped textured structure 11). By controlling the reaction temperature and reaction time, after the reaction is completed, the etched silicon substrate 110 is cleaned with nitric acid (HNO3) or aqua regia (HCl:HNO3 = 3:1) to remove residual Ag NPs.

[0037] In this embodiment, a textured structure 111 is formed on the surface of the silicon substrate 110. The textured structure 111 is columnar, with a diameter of 0.5–3 μm and an aspect ratio > 5:1. Light is scattered multiple times between the textured structures 111, extending the light propagation path within the silicon substrate 110 and increasing the probability of light absorption by the silicon material. Simultaneously, resonant modes are excited, causing light of specific wavelengths to resonate within the nanowires, enhancing the interaction between light and the silicon material. This combined effect of multiple scattering and resonant mode enhancement reduces light reflectivity and improves spectral absorption performance.

[0038] In some embodiments, the textured structure 11 is disposed on the light-facing surface of the silicon substrate 110.

[0039] The silicon substrate 100 has two main surfaces: a light-facing surface and a back-lighting surface. The light-facing surface directly faces the sunlight, while the back-lighting surface is on the opposite side. The two surfaces are positioned opposite each other.

[0040] Specifically, two distinct regions, a first region 120 and a second region 130, are arranged alternately on the backlight surface of the silicon substrate 100. Specifically, a plurality of first regions 120 and a plurality of second regions 130 are arranged alternately along a first direction, and both first regions 120 and second regions 130 extend along a second direction, which intersects the first direction. The first regions 120 and second regions 130 can be arranged alternately along the transverse direction of the silicon substrate and both extend along the longitudinal direction; that is, the first direction can be the transverse direction of the back contact battery, and the second direction can be the longitudinal direction of the back contact battery, with the two perpendicular to each other. Of course, in other embodiments, the first and second directions can also be other directions, for example, they can be the diagonal directions of the silicon substrate, and no specific limitation is made here. The first regions 120 and second regions 130 do not overlap and are arranged adjacent to each other.

[0041] A first doped layer is disposed within a first region 120, and a second doped layer is disposed within a second region 130. The first and second doped layers have opposite polarities. Specifically, the first doped layer can be a P-type doped layer and the second doped layer can be an N-type doped layer, or vice versa. The first and second doped layers form regions with different electrical characteristics, supporting the formation of a PN junction and the separation of charge carriers.

[0042] In some embodiments, such as Figure 5 As shown, an interval region 140 is provided between the first region 120 and the second region 130.

[0043] Example 2

[0044] In some embodiments, the bottom diameter of the velvet structure 111 is larger than its top diameter.

[0045] The textured structure 11 is columnar, meaning that each cross-section of the textured structure 11 (the cross-section perpendicular to the extension direction of the textured structure 11) is circular or approximately circular. If it is circular, the diameter of the cross-section is the diameter of the circle; if it is approximately circular, it is the diameter of the largest circumscribed circle. The bottom diameter is the diameter of the bottom cross-section, and the top diameter is the diameter of the top cross-section. Specifically, in the process of preparing the textured structure 111 by metal-assisted chemical etching (MACE), the composition of the etching solution and the etching time are adjusted to achieve a structure with a bottom diameter larger than the top diameter. Specifically, in the initial stage of etching, a higher concentration of silver nitrate solution is used to catalyze the etching rate of the silver nanoparticles (Ag NPs) at the bottom, forming a coarser bottom. As etching progresses, the concentration of silver nitrate is appropriately reduced to slow down the etching rate of the top, thereby making the top diameter smaller.

[0046] The textured structure 111 has a shape that is thinner at the top and thicker at the bottom. The bottom is connected to the silicon substrate 110 and has a larger diameter, which provides stable support for the entire structure. The top diameter is smaller, which makes it easier for light to be scattered and refracted multiple times when it enters the textured structure 111.

[0047] When light enters from the narrower part at the top, it encounters structures with gradually increasing diameters during its propagation inside, which continuously changes the direction of propagation, increases the propagation path of light in the silicon substrate 110, and improves the light absorption efficiency.

[0048] In some embodiments, the diameter of the textured structure 111 decreases as the distance to the surface of the silicon substrate 110 increases. The textured structure 111 is generally tapered, with its diameter gradually decreasing upwards from the surface of the silicon substrate 110. This tapered structure allows light to better adapt to the scattering and absorption characteristics of different diameter regions as it propagates.

[0049] For different wavelengths of light, optimal absorption can be achieved within a suitable diameter region. Shorter wavelengths of light are more easily absorbed resonantly in the smaller diameter region at the top, while longer wavelengths of light have more opportunities for scattering and absorption in the larger diameter region at the bottom. At the same time, the gradient diameter structure allows light to enter the velvet structure 111 more smoothly, reducing light reflection on the surface and improving light utilization.

[0050] Example 3

[0051] In some embodiments, the top surface of the velvet structure 111 is a plane.

[0052] A flat top surface facilitates the uniform deposition of other functional layers, such as anti-reflective coatings and electrodes. For example, when depositing an anti-reflective coating, a flat top surface ensures uniform coating thickness and improves the anti-reflective effect. Simultaneously, a flat top surface allows light to enter the textured structure 111 more perpendicularly, reducing light scattering loss at the top and improving light incidence efficiency.

[0053] Example 4

[0054] In some embodiments, such as Figure 4 As shown, the textured structure 111 is uniformly distributed on the surface of the silicon substrate 110.

[0055] The textured structure 111 is neatly arranged on the surface of the silicon substrate 110, with the spacing and position of each columnar structure being relatively fixed, forming a regular pattern. This uniform distribution makes the optical properties of the entire silicon substrate 110 surface consistent.

[0056] Because the textured surface 111 is uniformly distributed, the absorption and conversion of light are consistent across the entire silicon substrate 110 surface, avoiding excessive differences in photoelectric conversion efficiency in localized areas. This results in more stable output current and voltage, reducing battery power fluctuations. Simultaneously, the uniformly distributed structure facilitates large-scale production and quality inspection, reducing the defect rate during manufacturing.

[0057] Example 5

[0058] In some embodiments, the height of the plurality of velvet structures 111 is 2.5 to 15 μm.

[0059] The height of the textured structure 11 fluctuates within a certain range, from 2.5 to 15 μm. When the height of the textured structure 11 is less than 2.5 μm, the light-trapping effect is significantly reduced. Due to the excessively short structure, the number of scattering and reflections of light within the textured surface is significantly reduced, failing to effectively extend the light propagation path in the silicon substrate. This results in insufficient interaction between light and silicon materials, significantly reducing the light absorption capacity, especially for long-wavelength light, which is difficult to capture and absorb effectively. Simultaneously, under these conditions, the ability of the textured structure 11 to excite resonant modes also weakens, failing to effectively enhance the absorption of specific wavelengths of light, leading to a deterioration in overall spectral absorption performance and severely impacting the photoelectric conversion efficiency of the solar cell.

[0060] However, when the height of the textured structure 11 exceeds 15 μm, several problems arise. Excessive height leads to decreased stability, making the textured structure 11 prone to tilting or breakage during subsequent battery manufacturing processes such as coating and electrode preparation, affecting battery quality and performance. Furthermore, an excessively tall textured structure 11 increases light loss during propagation; some light rays may be scattered multiple times within the structure and fail to reach the silicon substrate for effective absorption, thus reducing light utilization. Moreover, an excessively tall structure also increases manufacturing costs and process complexity, hindering large-scale production.

[0061] Example 6

[0062] In some embodiments, there is a gap between at least some of the adjacent velvet structures 111.

[0063] That is, at least some of the adjacent velvet structures 111 maintain a certain distance from each other, exist independently, and have no overlapping or intersecting parts, so that each velvet structure 111 can give full play to its optical performance.

[0064] Each textured structure 111 can independently scatter and absorb light, avoiding light interference and energy loss that may occur due to overlapping. During multiple scattering processes, light can propagate effectively within its respective textured structure 111, improving light absorption efficiency.

[0065] Preferably, at least 90% of the adjacent pile structures 111 have gaps between them. Most of the pile structures 111 have gaps between them, and only a small portion of the pile structures may overlap during growth.

[0066] In some embodiments, the spacing between adjacent textured structures 111 is 0.5–6 μm. Different spacings have different scattering and absorption effects on light of different wavelengths. Within a spacing range of 0.5–6 μm, a wider solar spectrum can be covered, achieving good absorption from visible light to near-infrared light. For example, smaller spacings (e.g., 0.5–2 μm) have better scattering and absorption effects on short-wavelength visible light, while larger spacings (e.g., 4–6 μm) are more effective for long-wavelength near-infrared light. By appropriately selecting the spacing, the battery can efficiently absorb light across the entire solar spectrum, improving photoelectric conversion efficiency.

[0067] Example 7

[0068] This embodiment provides a battery assembly, including the solar cell described in the above embodiment.

[0069] A battery module may include multiple back-contact solar cells. These back-contact solar cells can be connected in series to form a battery string. The battery strings can be connected in series, in parallel, or in a series-parallel combination to achieve current output. For example, the connection between the individual cells can be achieved by welding solder strips, or the connection between the battery strings can be achieved by busbars.

[0070] The battery module may also include a metal frame, a backsheet, photovoltaic glass, and an encapsulating film (not shown in the figures). The encapsulating film can be filled between the light-facing side of the solar cell and the photovoltaic glass, the back-facing side and the backsheet, and adjacent cells. As a filler, it can be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulating film can be EVA film or POE film, and the specific choice can be made according to the actual situation. There are no restrictions here.

[0071] Photovoltaic glass can be applied to the encapsulating film on the light-facing side of a solar cell. This photovoltaic glass can be ultra-clear glass, possessing high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, ultra-clear glass can achieve a light transmittance of over 92%, protecting the solar cell while minimizing impact on its efficiency. Simultaneously, the encapsulating film bonds the photovoltaic glass and the solar cell together, providing sealing, insulation, and waterproofing / moisture protection for the solar cell.

[0072] The backsheet can be attached to the encapsulating film on the back side of the solar cell. The backsheet protects and supports the solar cell, providing reliable insulation, water resistance, and aging resistance. Multiple backsheet options are available, typically including tempered glass, acrylic glass, and aluminum alloy TPT composite encapsulating film, etc. The specific choice depends on the specific circumstances and is not limited here. The backsheet, solar cell, encapsulating film, and photovoltaic glass can be mounted on a metal frame. The metal frame serves as the main external support structure for the entire battery module, providing stable support and installation. For example, the battery module can be installed at the desired location using the metal frame.

[0073] The beneficial effects of the battery module in this embodiment are equivalent to those of the solar cell described above, and will not be repeated here.

[0074] Example 8

[0075] This embodiment provides a photovoltaic system, characterized in that it includes the aforementioned battery module.

[0076] Photovoltaic systems can be applied in photovoltaic power plants, such as ground-mounted, rooftop, and floating power plants, as well as in equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it's understandable that the application scenarios of photovoltaic systems are not limited to these; that is, photovoltaic systems can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation network as an example, a photovoltaic system can include photovoltaic arrays, combiner boxes, and inverters. A photovoltaic array can be a combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic arrays are connected to combiner boxes, which collect the current generated by the photovoltaic arrays. The collected current flows through an inverter and is converted into AC power required by the mains grid before being connected to the mains grid to achieve solar power supply.

[0077] The beneficial effects of the photovoltaic system in this embodiment are equivalent to the beneficial effects of the battery module described above, and will not be repeated here.

[0078] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A solar cell, characterized in that, The invention includes a silicon substrate, wherein the light-facing surface of the silicon substrate has a plurality of textured structures, the textured structures are columnar, the diameter of the textured structures is 0.5~3μm, and the aspect ratio is >5:1; The cross-section of the velvet structure is circular or nearly circular, and the bottom diameter of the velvet structure is larger than the top diameter, exhibiting a shape that is thinner at the top and thicker at the bottom.

2. The solar cell as described in claim 1, characterized in that, The diameter of the textured structure decreases as the distance from the silicon substrate surface increases.

3. The solar cell as described in claim 1, characterized in that, The top surface of the velvet structure is a plane.

4. The solar cell as described in claim 1, characterized in that, The textured surface is uniformly distributed on the surface of the silicon substrate.

5. The solar cell as described in claim 1, characterized in that, The height of some of the described velvet structures is 2.5~15μm.

6. The solar cell as claimed in claim 1, characterized in that, There are gaps between at least some of the adjacent velvet structures.

7. The solar cell as claimed in claim 6, characterized in that, The spacing between adjacent velvet structures is 0.5~6μm.

8. A battery assembly, characterized in that, Includes the solar cell described in any one of claims 1-6.

9. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 8.

Images