A solar cell, a cell assembly, a photovoltaic system and a method for cutting a silicon rod

Abstract

The application is suitable for the photovoltaic technical field, and provides a solar cell, a cell assembly, a photovoltaic system and a silicon rod cutting method.The solar cell comprises a silicon substrate, and the orthographic projection of the silicon substrate is a rectangle;the surface of the silicon substrate has a plurality of pyramid base structures, and the pyramid base structure has a first edge line;the extension line of the first edge line respectively extends to two oppositely arranged first edges of the solar cell, and the included angle between the first edge line and the first edge is α, 45°<α<90°.The pyramid inclined surface on both sides of the edge line can obtain relatively balanced light irradiation and reflected light redistribution, and one side will not be in the shadow for a long time, so that the overall absorption efficiency is maximized.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic technology, and particularly relates to a solar cell, a battery module, a photovoltaic system, and a method for cutting silicon rods. Background Technology

[0002] In traditional crystalline silicon solar cell designs, pyramidal textured structures are widely used due to their excellent anti-reflection and light-trapping capabilities. However, conventional pyramidal arrays based on regular crystal orientation do not fully consider the dynamic changes in the direction of sunlight incidence throughout the day. Especially in fixed-installation photovoltaic systems, the constantly changing solar azimuth angle can cause certain sides of the textured structure to be in relatively unfavorable lighting geometry for extended periods, such as receiving weak light intensity or being shaded, thus limiting further improvements in overall light absorption efficiency throughout the day. Summary of the Invention

[0003] The present invention provides a solar cell designed to solve the problem of low overall light absorption efficiency of existing cells throughout the day.

[0004] The present invention is implemented as follows: a solar cell includes a silicon substrate having two first edges disposed opposite to each other; The surface of the silicon substrate has several pyramidal base structures, each pyramidal base structure having a first ridge. The extension lines of the first ridge extend toward the first edge of the solar cell, and the angle between the first ridge and the first edge is α, where 45° < α < 90°.

[0005] Alternatively, 55° < α < 75° Optionally, the silicon substrate further has two opposing second edges, and the pyramid base structure further has a second ridge, the orthographic projection of the second ridge and the orthographic projection of the first ridge being perpendicular to each other; The extension lines of the second ridge line extend toward the second edge of the solar cell, and the angle between the second ridge line and the second edge is β, where β = α.

[0006] Optionally, adjacent pyramid base structures may at least partially overlap.

[0007] Optionally, the length of the longest diagonal of the pyramid base structure ranges from 0.5 μm to 5 μm.

[0008] Optionally, the height of the pyramid base structure ranges from 0.3 μm to 3 μm.

[0009] Optionally, the first edge line includes a first branch edge and a second branch edge connected together, the orthographic projections of the first branch edge and the second branch edge are collinear, and the included angle between the first branch edge and the second branch edge is 52°~80°.

[0010] Optionally, the second edge line includes a connected third and fourth branch edge, the orthographic projections of the third and fourth branch edges are collinear, and the included angle between the third and fourth branch edges is 52° to 80°.

[0011] This invention also provides a battery assembly including the solar cell described above, wherein the mounting edge of the battery assembly is parallel to the edge of the solar cell.

[0012] This invention also provides a photovoltaic system including the aforementioned battery module.

[0013] This invention also provides a method for cutting a silicon rod, comprising the following steps: The trajectory of the sun on the solar cell is calculated based on the pre-installation location of the solar cell, and the azimuth angle α is obtained by quantification. The original cutting edge is determined based on two adjacent growth ridges on the sidewall of the silicon rod, and the original cutting edge is parallel to the saw blade of the cutting equipment. The silicon rod is rotated (90°-α°) to cut one edge; After rotating the silicon rod by 90°, another cutting edge is cut. This process is repeated three times to complete the silicon rod cutting.

[0014] The beneficial effects achieved by this invention are that, since the orthographic projection of the first edge of the pyramid base structure is parallel to the projection of the sun's trajectory onto the solar cell 100, and the angle between the first edge and the first edge 101 is α, 45° < α < 90°, the pyramid slopes on both sides of the edge can obtain relatively balanced light illumination and reflected light redistribution, and no one side will be in shadow for a long time, thereby maximizing the overall absorption efficiency. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a solar cell provided in an embodiment of the present invention; Figure 2 This is an electron microscope magnified image of the pyramid base structure provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the rotation of the silicon rod according to an embodiment of the present invention.

[0016] Explanation of reference numerals in the attached figures: 100. Solar cell; 101. First edge; 102. Second edge; 110. Silicon substrate; 120. Pyramid base structure; 121. First ridge line; 122. Second ridge line; 210. Extension of the first ridge line; 220. Extension of the second ridge line. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of 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 the invention, and should not be construed as limiting the invention. Furthermore, it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0018] In the description of this invention, 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 invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] 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 invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 invention according to the specific circumstances.

[0021] 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.

[0022] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0023] In this invention, the orthographic projection of the first edge of the pyramid base structure is parallel to the projection of the sun's trajectory onto the solar cell 100. The angle between the first edge and the first edge 101 is α, where 45° < α < 90°. This ensures that the pyramid slopes on both sides of the edge can receive relatively balanced light illumination and redistribution of reflected light, preventing any one side from being in shadow for an extended period, thereby maximizing the overall absorption efficiency.

[0024] Example 1 like Figure 1 As shown, this embodiment provides a solar cell 100, including: a silicon substrate 110, the silicon substrate 110 having two first edges disposed opposite to each other; The surface of the silicon substrate 110 has several pyramid base structures 120. Each pyramid base structure 120 has a first ridge 121. The extension lines 210 of the first ridge extend toward the first edge 101 of the solar cell 100. The angle between the first ridge 121 and the first edge 101 is α, where 45° < α < 90°.

[0025] The silicon substrate 110 is the base material of the solar cell, typically monocrystalline or polycrystalline silicon, usually cut from a silicon rod into wafers. Various functional layers (such as tunneling layers, doped layers, passivation layers, etc.) are stacked on the silicon wafers to form 100 solar cells. The surface of the silicon substrate 110 has several pyramidal base structures 120, which form a micro-texture structure on the surface of the silicon substrate 110, resembling pyramid-shaped protrusions. A single pyramidal base structure 120 is typically a square pyramid with four edges, of which two opposite edges are the first edges 121, and the orthographic projection of the first edges 121 is a straight line.

[0026] The silicon substrate 110 is typically rectangular or rectangular (e.g., with chamfered corners). The first edge 101 is one of the two opposite edges of the solar cell 100, which can be either two long edges or two short edges. The extension lines 210 of the first edge 121 extend toward the two first edges 101 respectively. The angle α between the first edge 121 and the first edge 101 is between 45° and 90° (excluding 45° and 90°), that is, the first edge 121 is inclined and not parallel to any edge of the cell.

[0027] Understandably, the conversion of solar cell 100 into electrical energy by absorbing sunlight is called photoelectric conversion. The photoelectric conversion efficiency of a solar cell directly depends on the number of photons it effectively absorbs. Specifically, the "sun's trajectory" determines the incident angle of sunlight at any given moment. The pyramid base structure 120 on the surface of the cell has fixed orientations and angles on each face. As the sun's position changes, the angle at which sunlight hits the pyramid also changes, which may create a long shadow area on a certain side of the pyramid, preventing the absorption of photons and hindering the improvement of photoelectric conversion efficiency.

[0028] The "solar path" refers to the sun's movement along its path throughout the day (its azimuth changes). Observed from a fixed location, the sun moves across the sky from east to west throughout the day, its azimuth constantly changing. The projection of this path onto the sky is an arc. For a fixed solar panel placed horizontally or at an angle, this arc of the sun's path will be projected onto the panel's surface, forming a straight line. This is the main direction of sunlight incident on the panel's surface throughout the day. In different regions, the direction of the sun's path projection onto the solar cell 100 varies slightly, but it generally follows a direction from east to west.

[0029] When light shines on the sloping sides of a pyramid, the angle at which the light enters is smaller than that on a flat surface. According to Fresnel's law, this itself reduces reflectivity. Light reflected from the first side has a high probability of hitting another side of an adjacent pyramid, thus gaining a second and third chance of being absorbed, which is the "light trap" effect.

[0030] The angle α between the first ridge 121 and the first edge 101 ranges from 45° to 90°, ensuring that the orthographic projection of the first ridge 121 is parallel to the projection of the sun's trajectory onto the solar cell 100. This means that the "valley" direction of the pyramid structure (i.e., the direction of the first ridge 121) aligns with the sun's movement direction (east-west). Several pyramid base structures 120 are arranged to form several parallel "ridges" running north-south and east-west, creating symmetrical and balanced light reception conditions on both sides of the ridges. This ensures that regardless of the sun's position throughout the day, the pyramid slopes on both sides of the ridge receive relatively balanced light and reflected light redistribution, preventing any one side from being in shadow for extended periods, thus maximizing overall absorption efficiency.

[0031] Specifically, the solar cell 100 has two opposite edges arranged along a first direction, which are called first edges 101, and two opposite edges arranged along a second direction, which are called second edges 102. The first and second directions are perpendicular. The first edges 101 and the second edges 102 are perpendicular, and the angle between them is 90°. It should be noted that in this embodiment, the "angle" is an acute angle between the two that is less than 90°. The angle between the first edge line 121 and the first edge 101 is less than 90°, that is, the angle between the first edge line 121 and the first edge 101 is not 90°, so the first edge line 121 and the second edge 102 are not parallel. The angle between the first edge 121 and the first edge 101 is greater than 45°. In this case, the extension line 210 of the first edge extends toward the two first edges 101. If the angle between the first edge 121 and the first edge 101 is less than 45°, then the angle between the first edge 121 and the second edge 102 is greater than 45°, and the extension line 210 of the first edge extends toward the two second edges 102.

[0032] Typically, solar cells are installed with their edges positioned, arranged sequentially. The solar panel 100 is mounted on a bracket with a fixed azimuth and tilt angle. If the pyramid's edges are parallel to the panel edges (usually north-south / east-west), the optical characteristics of the pyramid array are symmetrical in both directions. However, the actual direction of incident light is not symmetrical. For example, for a south-facing panel, morning and afternoon light primarily comes from the east-west direction with a large angle of incidence. This mismatch between the symmetrical structure and the asymmetrical incidence results in increased light reflectivity at specific times or seasons. By tilting the first edge 121, making it non-parallel to any cell edge, the orientation lock between the pyramid array and the panel frame is broken. This allows the pyramid array to "actively adapt" to the optimal incident light direction, rather than passively accepting the default orientation aligned with the frame.

[0033] In a specific example, when the solar cell 100 is a TOPCon cell, a first doped layer is disposed on the light-facing side of the silicon substrate 110, and a second doped layer is disposed on the back-facing side of the silicon substrate 110. The first and second doped layers have opposite polarities. For example, the silicon substrate 110 is an N-type silicon substrate, the second doped layer is a phosphorus-doped polycrystalline silicon layer, and the first doped layer is a boron diffusion layer. The pyramid base structure 120 is disposed on the light-facing side.

[0034] In another specific example, when the solar cell 100 is a BC cell, a first doped layer and a second doped layer are alternately disposed along a first direction on the back surface of the silicon substrate 110, with a gap between the first doped layer and the second doped layer. The pyramid base structure 120 is disposed in the gap between the light-facing surface and the back surface.

[0035] When setting up the pyramid base structure 120, the specific installation state of the solar cells is fully considered, such as the installation orientation of the solar cells (the orientation of the edges of the solar cells), so that in the final use state of the solar cells, the orthographic projection of the first edge line 121 is parallel to the projection of the sun's trajectory onto the solar cell 100.

[0036] In this embodiment, the angle between the first ridge 121 and the first edge 101 is α, where 45° < α < 90°. This ensures that the orthographic projection of the first ridge 121 of the pyramid base structure 120 is parallel to the projection of the sun's path onto the solar cell 100. Consequently, the pyramid slopes on both sides of the ridge can receive relatively balanced light illumination and reflected light redistribution, preventing any one side from being in shadow for an extended period, thus maximizing the overall absorption efficiency.

[0037] Furthermore, 55° < α < 75°. This applies to most installation scenarios.

[0038] Specifically, the first edge line 121 includes a first branch edge and a second branch edge connected together. The orthographic projections of the first branch edge and the second branch edge are collinear, and the included angle between the first branch edge and the second branch edge is 52°~80°.

[0039] The first and second lateral edges intersect at the vertices of the pyramid. Their orthographic projections onto the silicon substrate 110 are collinear and parallel to the projection of the sun's trajectory onto the silicon substrate 110. The angle between the first and second lateral edges is 52° to 80°. When the angle is too small (less than 52°), the top of the pyramid becomes abnormally sharp, and the two side slopes become abnormally steep. The projected area of ​​the steep slopes facing the effective incident light is greatly reduced, and the light-receiving area is severely weakened. When the angle is too large (greater than 80°), the two side slopes of the pyramid become very gentle, and its geometry is closer to a gentle mound. The sensitivity to the direction of incident light decreases, the direction of light reflection changes less, and it is difficult to effectively guide the light to the adjacent slope, thus reducing the light-trapping effect. By keeping the angle between 52° and 80°, the two main working faces of the pyramid can maintain a sufficiently large effective light-receiving projected area and a high probability of internal reflection paths, achieving both "equal illumination" and "efficient light trapping."

[0040] In some embodiments, the pyramid base structure 120 further has a second ridge 122, the orthographic projection of the second ridge 122 and the orthographic projection of the first ridge 121 being perpendicular to each other. The extension line 220 of the second ridge line extends to the two oppositely arranged second edges 102 of the solar cell 100, and the included angle between the second ridge line 122 and the second edge 102 is β, where β = α.

[0041] A single pyramid base structure 120 is typically a square pyramid with four edges. Two opposite edges are designated as the first edge 121, and the other two opposite edges are designated as the second edge 122. The orthographic projection of the second edge 122 is perpendicular to the orthographic projection of the first edge 121. Extensions 220 of the second edges extend to the two second edges 102, which are perpendicular to the first and second edges 102. Therefore, the angle between the second edge 122 and the second edge 102 is equal to the angle between the first edge 121 and the first edge 101. In other words, the angle between the second edge 122 and the second edge 102 is β, where β = α.

[0042] Specifically, the second edge 122 includes a connected third and fourth tributary edges. The orthographic projections of the third and fourth tributary edges are collinear, and the included angle between the third and fourth tributary edges is 52° to 80°, which will not be elaborated here. The included angle between the third and fourth tributary edges is equal to or similar to the included angle between the first and second tributary edges, and the angle difference between the two is less than or equal to 6°.

[0043] Typically, when the first edge 121 and the second edge 122 are perpendicular, and the angle between the first and second lateral edges is equal to the angle between the third and fourth lateral edges, the pyramid base structure 120 is a regular square pyramid. For example, a regular square pyramid pyramid base structure 120 is formed by etching the surface of a single-crystal silicon wafer with an alkaline solution (such as KOH or NaOH).

[0044] In some embodiments, adjacent pyramidal base structures 120 at least partially overlap. On the one hand, the flat "valley" regions between the pyramids have poor anti-reflection effects on light (approaching the reflectivity of planar silicon). A large portion of the light incident on these regions is directly reflected and lost. The overlap of the bases greatly reduces these flat "optical dead zones," allowing the entire cell surface to be almost completely covered by the pyramidal slopes with an angled design. Regardless of where the light enters from, the surface it first contacts is highly likely to be a slope with an optimized angle, minimizing the initial reflectivity and allowing more light to enter the silicon mass upon first contact, creating a more favorable starting point for subsequent light-trapping effects.

[0045] On the other hand, because the bases of the pyramids are interconnected or tilted, light reflected from one pyramid's slope does not necessarily reach the corresponding slope of the adjacent pyramid directly. It may enter the complex curved surface or edge of the overlapping area of ​​the two pyramids, where it undergoes secondary or even multiple scatterings before entering the main body of another pyramid. This can more effectively disrupt the direction of the light, allowing it to have more opportunities to come into contact with the silicon material before escaping the surface, thereby increasing the overall absorption probability.

[0046] In some embodiments, the length of the longest diagonal of the pyramid base structure 120 ranges from 0.5 μm to 5 μm.

[0047] The orthographic projections of the first edge 121 and the second edge 122 of the pyramid base structure 120 onto the silicon substrate 110 are the two diagonals of the pyramid base structure 120, with the longer one being the longest diagonal. The longer the longest diagonal, the larger the size of the pyramid base structure 120. When the length of the longest diagonal is greater than 5 μm, the pyramid slope becomes relatively gentle, resulting in a poorer anti-reflection effect for short-wavelength light (such as blue light and ultraviolet light); while when the length of the longest diagonal is less than 0.5 μm, the light "sees" an approximately smooth but rough surface (Rayleigh scattering region), resulting in limited anti-reflection effect and potentially introducing undesirable scattering. Pyramid base structures 120 with a longest diagonal length in the range of 0.5 μm to 5 μm can provide excellent anti-reflection effects for a broad spectrum of sunlight from ultraviolet to near-infrared, significantly improving photocurrent.

[0048] In some embodiments, the height of the pyramid base structure 120 ranges from 0.3 μm to 3 μm. When the height is less than 0.3 μm, the pyramid resembles a "low hill," and light may escape after only one reflection, resulting in weak light-trapping ability. As the height increases, if the base size remains constant, the pyramid becomes more "sharp." For pyramids exceeding 3 μm in height, the radius of curvature at the tip becomes extremely small, making it difficult for passivation processes such as atomic layer deposition to form a uniform, defect-free, high-quality passivation layer on such a sharp tip, which easily becomes a "leak point" with an extremely high recombination rate. Setting the upper limit of the height at 3 μm matches the upper limit of the base size at 5 μm, in order to obtain excellent optical performance while ensuring that the geometry of the pyramid is not too extreme, thus enabling reliable implementation of tip passivation and electrode contact processes.

[0049] Example 2 A method for cutting silicon rods: S1. Calculate the trajectory of the sun on the solar cell 100 based on the pre-installation location of the solar cell 100, and quantify the azimuth angle α. S2. Determine the original cutting edge based on two adjacent growth ridges on the sidewall of the silicon rod. The original cutting edge is parallel to the saw blade of the cutting equipment. S3. Rotate the silicon rod (90°-α°) to cut one cutting edge; S4. After rotating the silicon rod by 90°, cut the other cutting edge. Repeat this process three times to complete the silicon rod cutting.

[0050] In step S1, based on the geographical latitude and installation tilt angle of the pre-installation location of the solar cell 100, and using astronomical calculation formulas for solar altitude angle and azimuth angle, a representative time period (such as the vernal / autumnal equinox, or the annual average) is selected to simulate the sun's projection trajectory on the solar panel plane at that specific location, orientation, and tilt angle. This projection trajectory approximates a straight line or a great circle arc on the solar panel plane. Taking its main direction of movement (such as from east-southeast to west-northwest), and using one edge of the solar cell 100 as a reference edge, the angle α between the reference edge and the trajectory is obtained.

[0051] In step S2, the silicon rod is typically cylindrical. The longitudinal growth ridges (usually parallel to the silicon rod axis) naturally formed during the Czochralski (CZ) single-crystal silicon rod growth process serve as natural orientation markers. There are four growth ridges around the sidewall of the silicon rod. Two adjacent growth ridges are selected, and the plane formed by these two ridges (or simply, the chord connecting the points on the same cross-section of the silicon rod) is defined as the "original reference direction," i.e., the original cutting edge. When clamping the silicon rod, the rod's orientation is adjusted so that this original cutting edge is strictly parallel to the plane of the saw blade of the cutting equipment. At this point, the direction of the saw blade is aligned with this natural crystallographic feature of the silicon rod; that is, the original cutting edge is parallel to the first ridge, and the angle between them is 0°.

[0052] In step S3, the original cutting edge (parallel to the saw blade) is rotated by an angle from its initial position, such as... Figure 3 As shown, the new edge after rotation satisfies the angle α relationship with the "first edge of the pyramid". This rotation angle is (90° - α) (or (α - 90°, depending on the definition of the rotation direction).

[0053] In step S4, after the first edge is cut, the silicon ingot is precisely rotated 90° around its central axis. On precision CNC cutting equipment, this is typically achieved using a high-precision rotary table. A second cut is then performed, this cut surface being perpendicular to the first cut surface. Another 90° rotation is performed for a third cut; then another 90° rotation for a fourth cut. After cutting, a silicon ingot with a rectangular cross-section is obtained. Because each rotation is precisely 90° and the direction of the first cut is locked, the four sides of the silicon ingot are either parallel or perpendicular to each other.

[0054] The silicon ingot is then cut into several silicon wafers, and the pyramid base structure 120 formed on the silicon wafers is aligned with the pyramid base structure 120 on the end face of the silicon rod.

[0055] Example 3 This embodiment provides a battery assembly, including the solar cell 100 described above.

[0056] The battery module may include multiple solar cells 100 pieces. The multiple solar cells 100 pieces in the battery module 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 collection and output. For example, the connection between the individual cells can be achieved by welding the welding strips, or the connection between the battery strings can be achieved by using bus bars.

[0057] The battery module may also include a metal frame, a backsheet, photovoltaic glass, and an encapsulant film (not shown in the figures). The encapsulant film can be filled between the light-facing side of the solar cell 100 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 encapsulant 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.

[0058] Photovoltaic glass can be applied to the encapsulating film on the light-facing side of the solar cell 100. The photovoltaic glass can be ultra-clear glass, which has 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%. It can protect the solar cell 100 while minimizing impact on its efficiency. Simultaneously, the encapsulating film bonds the photovoltaic glass and the solar cell 100 together, providing sealing, insulation, waterproofing, and moisture protection for the solar cell 100.

[0059] The backsheet can be attached to the adhesive film on the back side of the solar cell 100. The backsheet provides protection and support for the solar cell 100, offering reliable insulation, water resistance, and aging resistance. Multiple backsheet options are available, typically including tempered glass, acrylic glass, and aluminum alloy TPT composite adhesive film, etc. The specific choice depends on the specific circumstances and is not limited here. The backsheet, solar cell 100, adhesive 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.

[0060] The beneficial effects of the battery module in this embodiment are equivalent to those of the solar cell 100 described above, and will not be repeated here.

[0061] Example 4 This embodiment provides a photovoltaic system, including the aforementioned battery module.

[0062] 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.

[0063] 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.

[0064] It is understood that those skilled in the art can combine various implementation methods in the above embodiments under the guidance of the above examples to obtain technical solutions with multiple implementation methods.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A solar cell, characterized in that, include: A silicon substrate having two first edges disposed opposite to each other; The surface of the silicon substrate has several pyramidal base structures, each pyramidal base structure having a first ridge. The extension lines of the first ridge extend toward the first edge of the solar cell, and the angle between the first ridge and the first edge is α, where 45° < α < 90°.

2. The solar cell as described in claim 1, characterized in that, 55°＜α＜75°。 3. The solar cell as described in claim 1 or 2, characterized in that, The silicon substrate also has two opposing second edges, and the pyramid base structure also has a second ridge line, the orthographic projection of the second ridge line and the orthographic projection of the first ridge line being perpendicular to each other; The extension lines of the second ridge line extend toward the second edge of the solar cell, and the angle between the second ridge line and the second edge is β, where β = α.

4. The solar cell as described in claim 1, characterized in that, The adjacent pyramid base structures at least partially overlap.

5. The solar cell as described in claim 1, characterized in that, The longest diagonal of the pyramid base structure ranges from 0.5μm to 5μm.

6. The solar cell as claimed in claim 1, characterized in that, The height of the pyramid base structure ranges from 0.3μm to 3μm.

7. The solar cell according to claim 1, characterized in that, The first edge line includes a first branch edge and a second branch edge connected together. The orthographic projections of the first branch edge and the second branch edge are collinear. The included angle between the first branch edge and the second branch edge is 52°~80°.

8. The solar cell as described in claim 3, characterized in that, The second edge line includes a connected third and fourth branch edge, the orthographic projections of the third and fourth branch edges are collinear, and the included angle between the third and fourth branch edges is 52°~80°.

9. A battery assembly, characterized in that, The solar cell includes any one of claims 1 to 8, wherein the mounting edge of the battery assembly is parallel to the edge of the solar cell.

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

11. A method for cutting a silicon rod, characterized in that, Includes the following steps: The azimuth angle α is obtained by calculating the sun's trajectory on the solar cell based on the pre-installation location of the solar cell; The original cutting edge is determined based on two adjacent growth ridges on the sidewall of the silicon rod, and the original cutting edge is parallel to the saw blade of the cutting equipment. The silicon rod is rotated (90°-α°) to cut one edge; After rotating the silicon rod by 90°, another cutting edge is cut. This process is repeated three times to complete the silicon rod cutting.

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