A solar cell, a battery module and a photovoltaic system

Abstract

This invention relates to the field of photovoltaic technology, providing a solar cell, a battery module, and a photovoltaic system. The solar cell includes: a silicon wafer, comprising a back side and a front side disposed opposite to each other; a first doped layer and a second doped layer, both located on the back side, or the first doped layer on the back side and the second doped layer on the front side; a first electrode located on the first doped layer and in contact with the first doped layer; a second electrode located on the second doped layer and in contact with the second doped layer; and a reflective insulating layer disposed on the back side, the reflective insulating layer at least covering a portion of the first doped layer, the side of the reflective insulating layer facing away from the silicon wafer having a plurality of reflective units arranged sequentially along a first direction, each reflective unit including a protrusion and a recess, the protrusion and the recess being connected to each other. The solar cell of this invention can reduce the loss of sunlight escaping from the back side and improve the cell conversion efficiency.

Description

Technical Field

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

[0002] A solar cell is a semiconductor device that converts solar energy into electrical energy. Under sunlight, a solar cell generates a photocurrent, which is then output as electrical energy through electrodes. In recent years, solar cell manufacturing technology has continuously improved, production costs have decreased, and conversion efficiency has increased. As a result, solar cell power generation has become increasingly widespread and is a crucial energy source for electricity supply.

[0003] In related technologies, because the silicon wafer of a solar cell has different absorption probabilities for different wavelengths of light, some sunlight can pass through the solar cell and escape from the back. In particular, for long-wavelength sunlight, the photons have low energy. When long-wavelength light reaches the back of the solar cell, it cannot be completely absorbed by the silicon wafer, thus failing to make full use of sunlight. Therefore, solar cells have the problem that sunlight can easily escape from the back, resulting in low sunlight utilization and poor cell conversion efficiency. Utility Model Content

[0004] This invention provides a solar cell designed to address the problem that existing solar cells suffer from poor conversion efficiency due to sunlight easily escaping from the back of the solar cell, resulting in low sunlight utilization.

[0005] This invention is implemented by providing a solar cell, comprising: A silicon wafer, the silicon wafer including a back side and a front side disposed opposite to each other; A first doped layer and a second doped layer are disposed on the silicon wafer, wherein both the first doped layer and the second doped layer are located on the back side, or the first doped layer is located on the back side and the second doped layer is located on the front side; A first electrode is located on the first doped layer, and the first electrode is in contact with the first doped layer; A second electrode is located on the second doped layer, and the second electrode is in contact with the second doped layer; and A reflective insulating layer is disposed on the back side, the reflective insulating layer at least covers a portion of the first doped layer, and the side of the reflective insulating layer facing away from the silicon wafer has a plurality of reflective units arranged sequentially along a first direction. Each reflective unit includes a protruding part and a recessed part that is recessed relative to the protruding part, and the protruding part and the recessed part are connected to each other.

[0006] Preferably, the reflective insulating layer has an average reflectivity of 50% to 95% for light with a wavelength range of 800 nm to 1200 nm.

[0007] Preferably, the plurality of the reflective units are arranged periodically along the first direction.

[0008] Preferably, two adjacent reflective units are connected together, and the protrusions and concave portions are alternately arranged along the first direction.

[0009] Preferably, the width of the protrusion along the first direction is the same as the width of the concave portion along the first direction.

[0010] Preferably, the height of the protrusion is the same as the depth of the recess.

[0011] Preferably, the shape of the protrusion is the same as the shape of the concave portion.

[0012] Preferably, the cross-sectional shape of the protrusion and the recess in the thickness direction of the silicon wafer is square, triangular or trapezoidal.

[0013] Preferably, the sum of the widths of the protrusion and the concave portion along the first direction is 2 to 10 micrometers.

[0014] Preferably, the difference between the thickness of the reflective insulating layer at the convex position and the thickness of the reflective insulating layer at the concave position is 0.5 to 2 micrometers.

[0015] Preferably, both the first doped layer and the second doped layer are located on the back side, and the reflective insulating layer covers at least a portion of the first doped layer and / or the second doped layer.

[0016] Preferably, the reflective insulating layer covers a portion of at least one of the first electrode and the second electrode.

[0017] Preferably, the back side of the silicon wafer further includes an isolation region disposed between the first doped layer and the second doped layer, and the reflective insulating layer covers at least a portion of the isolation region.

[0018] Preferred options also include: A first passivation layer is disposed on the back side, the first passivation layer being at least disposed between the reflective insulating layer and the first doped layer and between the reflective insulating layer and the second doped layer, the first electrode passing through the first passivation layer and contacting the first doped layer, and the second electrode passing through the first passivation layer and contacting the second doped layer.

[0019] Preferably, the first passivation layer covers the isolation region, and the reflective insulating layer covers the first passivation layer on the isolation region.

[0020] Preferably, the first doped layer is located on the back side, the second doped layer is located on the front side, and the reflective insulating layer covers the first doped layer.

[0021] Preferably, the first doped layer is continuously disposed on the back surface; or, the first doped layer is intermittently disposed on the back surface, with a gap region between adjacent first doped layers, and the reflective insulating layer covers at least a portion of the gap region.

[0022] Preferred options also include: A first passivation layer is disposed on the back side, the first passivation layer being at least disposed between the reflective insulating layer and the first doped layer, and the first electrode passes through the first passivation layer and contacts the first doped layer.

[0023] Preferably, the first passivation layer covers the spacer region, and the reflective insulating layer covers the first passivation layer on the spacer region.

[0024] Preferably, the reflective insulating layer covers a portion of the first electrode.

[0025] This invention also provides a battery assembly, including the aforementioned solar cell.

[0026] This utility model also provides a photovoltaic system, including the above-mentioned battery components.

[0027] This invention provides a solar cell that uses a reflective insulating layer on the back of a silicon wafer. The reflective insulating layer covers at least a portion of the first doped layer. By reflecting at least a portion of the sunlight transmitted through the silicon wafer back to the wafer, the optical path of the sunlight is increased, thereby reducing the loss of sunlight escaping from the back of the solar cell. In particular, it can reduce the loss of long-wavelength sunlight from the back of the solar cell, improving the utilization rate of sunlight and thus increasing the cell conversion efficiency. Furthermore, the side of the reflective insulating layer facing away from the silicon wafer has a plurality of reflective units arranged sequentially along a first direction. Each reflective unit includes a protrusion and a concave portion arranged in contact. The protrusion and concave portion of each reflective unit form a high-low structure, so that the morphology of the side of the reflective insulating layer facing away from the silicon wafer is arranged with alternating high and low shapes. Light rays incident from inside the silicon wafer to the back can form a diffraction grating effect after being reflected by the plurality of reflective units. The plurality of reflective units redirect the diffracted light back into the silicon wafer, further improving the utilization rate of sunlight by the solar cell and thus further improving the cell conversion efficiency. Attached Figure Description

[0028] Figure 1 A cross-sectional schematic diagram of a solar cell provided in an embodiment of this utility model; Figure 2 for Figure 1 A magnified schematic diagram of part A in the middle; Figure 3 A cross-sectional schematic diagram of another solar cell provided in an embodiment of this utility model; Figure 4 This is a cross-sectional schematic diagram of another type of solar cell provided in this embodiment of the present invention. Detailed Implementation

[0029] 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 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 present utility model, and should not be construed as limiting the present utility model. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining the present utility model and are not intended to limit the present utility model.

[0030] In the description of this utility model, it should be understood that the terms "upper", "lower", "backlight", "front", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the 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.

[0031] 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.

[0032] 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; however, those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0033] Please refer to Figures 1-3 The present invention provides a solar cell 100, comprising: Silicon wafer 1, which includes a back side 11 and a front side 12 disposed opposite to each other; A first doped layer 2 and a second doped layer 3 are disposed on a silicon wafer 1. Both the first doped layer 2 and the second doped layer 3 are located on the back side 11 of the silicon wafer 1, or the first doped layer 2 is located on the back side 11 of the silicon wafer 1 and the second doped layer 3 is located on the front side 12 of the silicon wafer 1. The first electrode 4 is located on the first doped layer 2 and is in contact with the first doped layer 2. The second electrode 5 is located on the second doped layer 3, and the second electrode 5 is in contact with the second doped layer 3; and A reflective insulating layer 6 is provided on the back side 11. The reflective insulating layer 6 covers at least a portion of the first doped layer 2. The side of the reflective insulating layer 6 facing away from the silicon wafer 1 has a plurality of reflective units 61 arranged sequentially along the first direction X. Each reflective unit 6 includes a protruding part 611 and a recessed part 612 that is recessed relative to the protruding part 611. The protruding part 611 and the recessed part 612 are connected to each other.

[0034] In this embodiment of the invention, the solar cell 100 can be a back-contact solar cell or a double-sided contact solar cell 100.

[0035] like Figure 1As shown in the figure, in one embodiment of this utility model, the solar cell 100 is a back-contact solar cell. The first doped layer 2 and the second doped layer 3 are both located on the back side 11 of the silicon wafer 1, and the first doped layer 2 and the second doped layer 3 are alternately disposed on the back side 11 of the silicon wafer 1 along the first direction X. The first electrode 4 and the second electrode 5 are both disposed on the back side 11 of the solar cell 100, while no electrodes are disposed on the front side 12 of the solar cell 100. Specifically, the back side 11 of the silicon wafer 1 is the back-lighting surface of the solar cell 100, that is, the side of the solar cell 100 that faces away from sunlight when it is working. The front side 12 of the silicon wafer 1 is specifically the light-facing surface of the solar cell 100, that is, the side of the solar cell 100 that faces sunlight when it is working. There are multiple first doped layers 2 and multiple second doped layers 3, and these multiple first doped layers 2 and multiple second doped layers 3 are alternately disposed along the first direction X.

[0036] like Figure 3 As shown in the figure, as an embodiment of the present invention, the solar cell 100 is a double-sided contact solar cell. The first doped layer 2 is located on the back side 11 of the silicon wafer 1, and the second doped layer 3 is located on the front side 12 of the silicon wafer 1. The first electrode 4 is disposed on the back side 11 of the solar cell 100, and the second electrode 5 is disposed on the front side 12 of the solar cell 100. The back side 11 of the silicon wafer 1 is specifically the back-light side of the solar cell 100, that is, the side of the solar cell 100 that faces away from sunlight when it is working. The front side 12 of the silicon wafer 1 is specifically the light-facing side of the solar cell 100, that is, the side of the solar cell 100 that faces sunlight when it is working. In this embodiment, the first doped layer 2 can cover the entire back side 11 of the solar cell 100, or it can only cover a local area of ​​the back side 11. Similarly, the second doped layer 3 can cover the entire front side 12 of the solar cell 100, or it can only cover a local area of ​​the front side 12.

[0037] In this embodiment of the invention, the first doped layer 2 and the second doped layer 3 are, respectively, a P-type doped layer and an N-type doped layer. The first doped layer 2 is a P-type doped layer, and the region containing the first doped layer 2 is a P-type doped region; the second doped layer 3 is an N-type doped layer, and the region containing the second doped layer 3 is an N-type doped region. Alternatively, the first doped layer 2 is an N-type doped layer, and the second doped layer 3 is a P-type doped layer. The P-type doped layer contains a P-type element, and the N-type doped layer contains an N-type element, for example, boron for the P-type element and phosphorus for the N-type element.

[0038] In this embodiment of the present invention, the protrusion 611 is raised relative to the side of the reflective insulating layer 6 away from the silicon wafer 1 (i.e., the side of the reflective insulating layer 6 away from the silicon wafer 1), and the concave portion 612 is recessed relative to the protrusion 611 toward the side where the silicon wafer 1 is located. The protrusion 611 and the concave portion 612 of each reflective unit 61 form a high-low structure, so that the morphology of the side of the reflective insulating layer 6 away from the silicon wafer 1 is arranged in an alternating "high-low-high-low" structure.

[0039] The solar cell 100 provided by this utility model adds a reflective insulating layer 6 to the back side 11 of a silicon wafer 1. The reflective insulating layer 6 covers at least a portion of the first doped layer 2. The reflective insulating layer 6 reflects at least a portion of the sunlight transmitted through the silicon wafer 1 back to the silicon wafer 1, increasing the optical path of the sunlight. In particular, it can reduce the loss of long-wavelength sunlight from the back side 11 of the solar cell 100, thereby improving the cell conversion efficiency. Moreover, the side of the reflective insulating layer 6 facing away from the silicon wafer 1 has a plurality of reflective units 61 arranged sequentially along the first direction X. Each reflective unit 61 includes a protrusion 611 and a recess 611. 12. The protrusions 611 and the recesses 612 are connected and arranged. The protrusions 611 and the recesses 612 of each reflective unit 61 form a high-low structure, so that the morphology of the side of the reflective insulating layer 6 facing away from the silicon wafer 1 is arranged with alternating high and low. Light rays from the inside of the silicon wafer 1 to the back surface 11 can form a diffraction grating effect after being reflected by several reflective units 61. This allows light rays from the inside of the silicon wafer 1 to the back surface 11 (especially long-wavelength light with large angles and difficult absorption) to be redirected back into the silicon wafer 1 after being reflected by several reflective units 61, further improving the light utilization rate and thus further improving the battery conversion efficiency.

[0040] As one embodiment of this utility model, the reflective insulating layer 6 has an average reflectivity of 50% to 95% for light with wavelengths in the range of 800nm ​​to 1200nm.

[0041] In this embodiment, the average reflectivity of the reflective insulating layer 6 for light with wavelengths in the range of 800nm ​​to 1200nm is controlled to be 50% to 95%, so that the reflective insulating layer 6 can better reduce the loss of long-wavelength (wavelength of 800nm ​​to 1200nm) sunlight escaping from the back side 11 of the solar cell 100, and better improve the cell conversion efficiency.

[0042] In one embodiment of this invention, the reflective insulating layer 6 comprises an organic resin and titanium dioxide, with the titanium dioxide accounting for 20% to 60% of the total weight of the reflective insulating layer 6. Specifically, the organic resin can be epoxy resin, and the titanium dioxide is titanium dioxide. Controlling the weight of titanium dioxide in the reflective insulating layer 6 to be 20% to 60% of its total weight ensures that the reflective insulating layer 6 is white and that its average reflectivity for light with wavelengths in the range of 800nm ​​to 1200nm is 50% to 95%. Furthermore, this ensures good insulation performance of the reflective insulating layer 6 and prevents leakage.

[0043] As one embodiment of this utility model, the thickness of the reflective insulating layer 6 is 10~100 micrometers.

[0044] In this embodiment, the thickness of the reflective insulating layer 6 is 10-100 micrometers, which can be understood as the thickness of the reflective insulating layer 6 at any position being within the range of 10-100 micrometers. By controlling the thickness of the reflective insulating layer 6 to be 10-100 micrometers, good reflectivity of the reflective insulating layer 6 for light with wavelengths in the range of 800nm-1200nm and good insulation performance of the reflective insulating layer 6 can be guaranteed.

[0045] For example, the thickness of the reflective insulating layer 6 can be any value among 10 micrometers, 15 micrometers, 18 micrometers, 20 micrometers, 22 micrometers, 28 micrometers, 30 micrometers, 33 micrometers, 37 micrometers, 40 micrometers, 42 micrometers, 46 micrometers, 50 micrometers, 55 micrometers, 60 micrometers, 65 micrometers, 70 micrometers, 72 micrometers, 78 micrometers, 80 micrometers, 81 micrometers, 84 micrometers, 88 micrometers, 90 micrometers, 92 micrometers, 96 micrometers, and 100 micrometers.

[0046] As one embodiment of this utility model, the thickness of the reflective insulating layer 6 is 35~45 micrometers.

[0047] In this embodiment, the thickness of the reflective insulating layer 6 is further controlled to be 35-45 micrometers, which further ensures the good reflectivity of the reflective insulating layer 6 for light with wavelengths in the range of 800nm-1200nm, and also ensures the good insulation effect of the reflective insulating layer 6, avoiding leakage.

[0048] In this embodiment of the invention, the first direction X specifically refers to the width direction of the first electrode 4 or the second electrode 5. A plurality of first electrodes 4 are sequentially spaced along the first direction X, and a plurality of second electrodes 5 are sequentially spaced along the first direction X. The specific number of reflective units 61 disposed on the side of the reflective insulating layer 6 facing away from the silicon wafer 1 is not limited. The number of protrusions 611 and recesses 612 included in each reflective unit 61 is also not limited. For example, each reflective unit 61 includes one protrusion 611 and one recess 612, with the protrusion 611 and the recess 612 connected; each reflective unit 61 may also include two or more protrusions 611 and two or more recesses 612, with the protrusions 611 and the recesses 612 alternating. This embodiment only illustrates that each reflective unit 61 includes one protrusion 611 and one recess 612. In some embodiments, a plurality of reflective units 61 on the side of the reflective insulating layer 6 facing away from the silicon wafer 1 may also be sequentially disposed along the length direction of the first electrode 4 or the second electrode 5, that is, sequentially disposed along a direction perpendicular to the first direction X.

[0049] In this embodiment of the invention, the protrusions 611 and concave portions 612 of each reflective unit 61 are arranged continuously or intermittently in a direction perpendicular to the first direction X. That is, the protrusions 611 and concave portions 612 of each reflective unit 61 are arranged in a strip shape or intermittently along the length of the first electrode 4 or the second electrode 5. Preferably, the protrusions 611 are strip-shaped protrusions along the length of the first electrode 4 or the second electrode 5, and the concave portions 612 are strip-shaped grooves along the length of the first electrode 4 or the second electrode 5. This allows light rays incident from the inside of the silicon wafer 1 to the back surface 11 to better form a diffraction grating effect after being reflected by several reflective units 61, which is beneficial for redirecting light rays incident from the inside of the silicon wafer 1 to the back surface 11 back into the silicon wafer 1, further improving the light utilization rate.

[0050] As one embodiment of the present invention, a plurality of reflective units 61 are arranged periodically along the first direction X.

[0051] In this embodiment, a plurality of reflective units 61 are arranged periodically along the first direction X. This can be understood as a plurality of reflective units 61 being arranged regularly on the side of the reflective insulating layer 6 away from the silicon wafer 1. Each reflective unit 61 has the same width and the spacing between adjacent reflective units 61 is the same. This allows light rays incident from inside the silicon wafer 1 to the back surface 11 to form a regularly distributed diffraction grating on the side of the reflective insulating layer 6 away from the silicon wafer 1. This allows sunlight passing through the back surface 11 of the silicon wafer 1 to be better reflected back into the silicon wafer 1, further improving light utilization and thus further improving battery conversion efficiency.

[0052] As an embodiment of the present invention, two adjacent reflective units 61 are connected together, and the protrusions 611 and the concave parts 612 are alternately arranged along the first direction X.

[0053] In this embodiment, two adjacent reflective units 61 are connected along the first direction X, so that the protrusions 611 and concave portions 612 on the side of the reflective insulating layer 6 facing away from the silicon wafer 1 are alternately arranged along the first direction X. This allows sunlight passing through the back side 11 of the silicon wafer 1 to be better reflected back into the silicon wafer 1 by the protrusions 611 and concave portions 612, thereby further improving the battery conversion efficiency.

[0054] As an embodiment of the present invention, the width W1 of the protrusion 611 along the first direction X is the same as the width W2 of the concave portion 612 along the first direction X.

[0055] In this embodiment, controlling the width W1 of the protrusion 611 along the first direction X to be the same as the width W2 of the recess 612 along the first direction X is more conducive to the formation of a diffraction grating effect by light rays incident from inside the silicon wafer 1 toward the back surface 11, thereby facilitating the redirection of light rays incident from inside the silicon wafer 1 toward the back surface 11 into the silicon wafer 1. Of course, in some embodiments, the width W1 of the protrusion 611 along the first direction X and the width W2 of the recess 612 along the first direction X may also be different. In addition, the width and height of the protrusion 611 of different reflective units 61 may be the same or different; the width and depth of the recess 612 of different reflective units 61 may be the same or different.

[0056] In one embodiment of this utility model, the height of the protrusion 611 is the same as the depth of the recess 612.

[0057] In this embodiment, the height of the protrusion 611 is the distance from the top of the protrusion 611 to the side of the reflective insulating layer 6 facing away from the silicon wafer 1, and the depth of the recess 612 is the distance from the top of the protrusion 611 to the bottom of the recess 612. The height of the protrusion 611 and the depth of the recess 612 are both H. Controlling the height of the protrusion 611 and the depth of the recess 612 to be the same facilitates the processing and fabrication of the reflective insulating layer 6, and further facilitates the formation of a diffraction grating effect by light rays incident from inside the silicon wafer 1 onto the back surface 11, and also facilitates the reflection of light rays incident from inside the silicon wafer 1 onto the back surface 11 back into the silicon wafer 1.

[0058] As an embodiment of the present invention, the shape of the protrusion 611 is the same as the shape of the concave portion 612.

[0059] In this embodiment, the shape of the protrusion 611 is the same as the shape of the concave portion 612, which facilitates the processing of the reflective insulating layer 6. Moreover, the shape of the protrusion 611 is the same as the shape of the concave portion 612, which is more conducive to the formation of a regular diffraction grating effect by the light rays from inside the silicon wafer 1 to the back surface 11, and more conducive to the redirection of the light rays from inside the silicon wafer 1 to the back surface 11 into the silicon wafer 1.

[0060] As an embodiment of the present invention, the cross-sectional shape of the protrusion 611 and the recess 612 in the thickness direction of the silicon wafer 1 is square, triangular or trapezoidal.

[0061] In this embodiment, the cross-sectional shape of the protrusion 611 and the recess 612 in the thickness direction of the silicon wafer 1 can be square, triangular, or trapezoidal, which can better form a diffraction grating effect. Preferably, the cross-sectional shape of the protrusion 611 and the recess 612 in the thickness direction of the silicon wafer 1 is square, which is not only easy to process, but also more conducive to the formation of a regular diffraction grating effect of light rays incident from inside the silicon wafer 1 to the back surface 11, and more conducive to the redirection of light rays incident from inside the silicon wafer 1 to the back surface 11 into the silicon wafer 1. Specifically, the cross-sectional shape of the protrusion 611 in the thickness direction of the silicon wafer 1 is a square protrusion, and the cross-sectional shape of the recess 612 in the thickness direction of the silicon wafer 1 is a square groove.

[0062] As an embodiment of the present invention, the sum of the widths W of the protrusions 611 and concave portions 612 of each reflective unit 61 along the first direction X is 2 to 10 micrometers.

[0063] In this embodiment, the sum W of the widths of the protrusion 611 and the concave portion 612 along the first direction X can be 2 to 10 micrometers, that is, the sum of the width W1 of the protrusion 611 along the first direction X and the width W2 of the concave portion 612 along the first direction X is 2 to 10 micrometers. This facilitates the formation of a diffraction grating effect and the processing of the protrusion 611 and the concave portion 612. For example, the sum of the widths of the protrusion 611 and the concave portion 612 along the first direction X can be any value among 2 micrometers, 2.2 micrometers, 2.8 micrometers, 3 micrometers, 3.5 micrometers, 4 micrometers, 4.3 micrometers, 5 micrometers, 5.2 micrometers, 5.8 micrometers, 6 micrometers, 6.7 micrometers, 7 micrometers, 7.5 micrometers, 8 micrometers, 8.6 micrometers, 9 micrometers, 9.5 micrometers, and 10 micrometers.

[0064] As an embodiment of the present invention, the difference between the thickness D1 of the reflective insulating layer 6 at the protrusion 611 and the thickness D2 of the reflective insulating layer 6 at the concave 612 is 0.5~2 micrometers.

[0065] In this embodiment, the thickness D1 of the reflective insulating layer 6 at the protrusion 611 and the thickness D2 of the reflective insulating layer 6 at the concave 612 are 0.5 to 2 micrometers, that is, the height difference between the protrusion 611 and the concave 612 is 0.5 to 2 micrometers, which is more conducive to the formation of a diffraction grating effect of sunlight passing through the back surface 11 of the silicon wafer 1, thereby further improving the reflection effect of the reflective insulating layer 6 on the sunlight passing through the back surface 11 of the silicon wafer 1.

[0066] like Figure 1As shown, in one embodiment of the present invention, the first doped layer 2 and the second doped layer 3 are both located on the back side 11 of the silicon wafer 1, and the reflective insulating layer 6 covers at least a portion of the first doped layer 2 and / or the second doped layer 3.

[0067] In this embodiment, the reflective insulating layer 6 covers at least a portion of the first doped layer 2 and / or the second doped layer 3 on the back surface 11. Specifically, the reflective insulating layer 6 may cover only a portion of the first doped layer 2, or it may cover the entire first doped layer 2; similarly, the reflective insulating layer 6 may cover only a portion of the second doped layer 3, or it may cover the entire second doped layer 3; or it may simultaneously cover both portions of the first doped layer 2 and the second doped layer 3, or it may cover the entire first doped layer 2 and the second doped layer 3. Preferably, the reflective insulating layer 6 covers the entire first doped layer 2 and the second doped layer 3, allowing sunlight passing through the first doped layer 2 and the second doped layer 3 on the back surface 11 of the silicon wafer 1 to be reflected back to the silicon wafer 1, thereby further improving sunlight utilization.

[0068] In some embodiments, the reflective insulating layer 6 covers a portion of at least one of the first electrode 4 and the second electrode 5.

[0069] In this embodiment, the reflective insulating layer 6 can cover the first doped layer 2 and / or the second doped layer 3, and can also cover a portion of the first electrode 4 or the second electrode 5, for example, a portion of the first electrode 4 or the second electrode 5, or both the first electrode 4 and the second electrode 5. The reflective insulating layer 6 can protect the first electrode 4 and the second electrode 5, and can also provide insulation and isolation between adjacent first electrodes 4 and second electrodes 5, thereby improving the insulation performance between the first electrode 4 and the second electrode 5.

[0070] As an embodiment of the present invention, the back side 11 of the silicon wafer 1 includes an isolation region 113 disposed between the first doped layer 2 and the second doped layer 3, and the reflective insulating layer 6 covers at least a portion of the isolation region 113.

[0071] In this embodiment, the isolation region 113 can specifically be a trench. The isolation region 113 can physically isolate the first doped layer 2 and the second doped layer 3, improving the insulation effect between the first doped layer 2 and the second doped layer 3. Moreover, the reflective insulating layer 6 covers at least a portion of the isolation region 113. By utilizing the reflective insulating layer 6 at the location of the isolation region 113 to reflect sunlight transmitted from the isolation region 113 back into the silicon wafer 1, the escape loss of sunlight on the back side 11 can be further reduced, and the cell conversion efficiency can be further improved.

[0072] As one embodiment of this utility model, it also includes: A first passivation layer 7 is provided on the back side 11. The first passivation layer 7 is at least disposed between the reflective insulating layer 6 and the first doped layer 2 and between the reflective insulating layer 6 and the second doped layer 3. The first electrode 4 passes through the first passivation layer 7 and contacts the first doped layer 2, and the second electrode 5 passes through the first passivation layer 7 and contacts the second doped layer 3.

[0073] In this embodiment, the first passivation layer 7 passesivates the surfaces of the first doped layer 2 and the second doped layer 3, which helps to improve battery efficiency. Optionally, the first passivation layer 7 is a stack of one or more of the following: a silicon nitride layer, a silicon oxynitride layer, and a silicon oxide layer.

[0074] As an embodiment of the present invention, the first passivation layer 7 covers the isolation region 113, and the reflective insulating layer 6 covers the first passivation layer 7 on the isolation region 113.

[0075] In this embodiment, the first passivation layer 7 passesivates the surface of the isolation region 113, which helps to improve battery efficiency. Moreover, the reflective insulating layer 6 covers the first passivation layer 7 on the isolation region 113. The reflective insulating layer 6 at the location of the isolation region 113 reflects the sunlight transmitted from the isolation region 113 back into the silicon wafer 1, which can further reduce the loss of sunlight escaping from the back side 11 and further improve the battery conversion efficiency.

[0076] Please refer to Figure 3 In another embodiment of the present invention, the first doped layer 2 is located on the back side 11 of the silicon wafer 1, the second doped layer 3 is located on the front side 12 of the silicon wafer 1, and the reflective insulating layer 6 covers at least a portion of the first doped layer 2.

[0077] In this embodiment, the solar cell 100 is specifically a double-sided contact solar cell 100. The first doped layer 2 is located on the back side 11 of the silicon wafer 1, and the second doped layer 3 is located on the front side 12 of the silicon wafer 1. The reflective insulating layer 6 can cover part of the first doped layer 2 or cover the entire area of ​​the first doped layer 2.

[0078] As an embodiment of the present invention, the first doped layer 2 is continuously disposed on the back side 11.

[0079] In this embodiment, the entire back surface 11 of the solar cell 100 is covered by the first doped layer 2, which helps to improve the passivation performance of the back surface 11. In this embodiment, the reflective insulating layer 6 completely covers the first doped layer 2.

[0080] Please refer to Figure 4 In another embodiment of the present invention, the first doped layer 2 is intermittently disposed on the back surface 11, and a spacer region 114 is disposed between adjacent first doped layers 2, and the reflective insulating layer 6 covers at least a portion of the spacer region 114.

[0081] In this embodiment, the first doped layer 2 does not completely cover the back surface 11 of the solar cell 100. The first doped layer 2 is only partially disposed on the back surface 11 of the solar cell 100, and a spacer region 114 is disposed between adjacent first doped layers 2. The reflective insulating layer 6 covers the first doped layer 2 and the spacer region 114. Because a spacer region 114 is disposed between adjacent first doped layers 2, it is beneficial to reduce the parasitic absorption of sunlight by the first doped layer 2, which is beneficial to improving the cell efficiency.

[0082] Please refer to this again. Figure 3 and Figure 4 As an embodiment of the present invention, the reflective insulating layer 6 covers a portion of the first electrode 4.

[0083] In this embodiment, the reflective insulating layer 6 can cover a portion of the first electrode 4. The reflective insulating layer 6 can provide corrosion protection for the first electrode 4, which helps to extend the service life of the first electrode 4.

[0084] As one embodiment of this utility model, it also includes: A first passivation layer 7 is disposed on the back side 11. The first passivation layer 7 is at least disposed between the reflective insulating layer 6 and the first doped layer 2. The first electrode 4 passes through the first passivation layer 7 and contacts the first doped layer 2.

[0085] In this embodiment, the first passivation layer 7 passesivates the surface of the first doped layer 2, which helps to improve battery efficiency.

[0086] please Figure 4 As an embodiment of the present invention, the first passivation layer 7 covers the spacer region 114, and the reflective insulating layer 6 covers the first passivation layer 7 on the spacer region 114.

[0087] In this embodiment, the first passivation layer 7 passivates the surface of the spacer region 114, which helps improve battery efficiency. Furthermore, the reflective insulating layer 6 covers the first passivation layer 7 on the spacer region 114. The reflective insulating layer 6 at the spacer region 114 reflects sunlight transmitted from the silicon wafer 1 through the spacer region 114 back into the silicon wafer 1, further reducing sunlight loss from the back side 11 and further improving battery conversion efficiency. Additionally, the second doped layer 3 can be intermittently disposed on the front side 12, that is, adjacent second doped layers 3 are also spaced apart, which helps reduce parasitic absorption of sunlight by the second doped layer 3, further improving battery efficiency.

[0088] As an embodiment of the present invention, it further includes a second passivation layer 8 disposed on the front side 12, the second passivation layer 8 covering the second doped layer 3, and the second electrode 5 passing through the second passivation layer 8 and contacting the second doped layer 3.

[0089] In this embodiment, the second passivation layer 8 passesivates the surface of the second doped layer 3, which helps to improve battery efficiency. The first passivation layer 7 and the second passivation layer 8 can both be one or more stacks of silicon nitride, silicon oxynitride, and silicon oxide.

[0090] This invention also provides a battery assembly, which includes the solar cell 100 described in the above embodiments. It should be noted that this battery assembly has the same or similar beneficial effects as the solar cell 100 described above, and the related aspects between the two can be referred to each other; to avoid repetition, they will not be repeated here.

[0091] In this embodiment, multiple solar cells 100 in the battery module can be connected in series to form a battery string, thereby realizing the series current collection and output. For example, the battery cells can be connected in series by setting solder strips (busbars, interconnecting strips), conductive backplates, etc.

[0092] It is understood that in such embodiments, the battery assembly may also include a metal frame, a backsheet, photovoltaic glass, and an encapsulating film. The encapsulating film can be filled between the front and back surfaces of the solar cells, the photovoltaic glass, adjacent cells, etc. As a filler, it can be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulating film can be an EVA film or a POE film, and the specific choice can be made according to the actual situation, without limitation.

[0093] Photovoltaic glass can be applied to the encapsulating film on the front side of the 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 100 while minimizing impact on its efficiency. Simultaneously, the encapsulating film bonds the photovoltaic glass and the solar cell 100 together, providing sealing, insulation, and waterproofing / moisture protection for the solar cell 100.

[0094] 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, 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.

[0095] This invention also provides a photovoltaic system, which includes the battery module described in the above embodiments. It should be noted that this photovoltaic system has the same or similar beneficial effects as the solar cell 100 described above, and the related aspects between the two can be referred to each other; to avoid repetition, they will not be repeated here.

[0096] In this embodiment, the photovoltaic system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to 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 is understood that the application scenarios of the photovoltaic system are not limited to these; that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple solar cell modules; for example, multiple solar cell modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0097] In the description of this specification, references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0098] 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, include: A silicon wafer, the silicon wafer including a back side and a front side disposed opposite to each other; A first doped layer and a second doped layer are disposed on the silicon wafer, wherein both the first doped layer and the second doped layer are located on the back side, or the first doped layer is located on the back side and the second doped layer is located on the front side; A first electrode is located on the first doped layer, and the first electrode is in contact with the first doped layer; A second electrode is located on the second doped layer, and the second electrode is in contact with the second doped layer; and A reflective insulating layer is disposed on the back side, the reflective insulating layer at least covers a portion of the first doped layer, and the side of the reflective insulating layer facing away from the silicon wafer has a plurality of reflective units arranged sequentially along a first direction. Each reflective unit includes a protruding part and a recessed part that is recessed relative to the protruding part, and the protruding part and the recessed part are connected to each other.

2. The solar cell according to claim 1, characterized in that, The reflective insulating layer has an average reflectivity of 50% to 95% for light with wavelengths in the range of 800 nm to 1200 nm.

3. The solar cell according to claim 1, characterized in that, The plurality of the reflective units are arranged periodically along the first direction.

4. The solar cell according to claim 1, characterized in that, Two adjacent reflective units are connected together, and the protrusions and concave portions are alternately arranged along the first direction.

5. The solar cell according to claim 1, characterized in that, The width of the protrusion along the first direction is the same as the width of the concave portion along the first direction.

6. The solar cell according to claim 1, characterized in that, The height of the protrusion is the same as the depth of the recess.

7. The solar cell according to claim 1, characterized in that, The shape of the protrusion is the same as the shape of the concave portion.

8. The solar cell according to claim 1, characterized in that, The cross-sectional shape of the protrusion and the recess in the thickness direction of the silicon wafer is square, triangular or trapezoidal.

9. The solar cell according to claim 1, characterized in that, The sum of the widths of the protrusion and the concave portion along the first direction is 2 to 10 micrometers.

10. The solar cell according to claim 1, characterized in that, The difference between the thickness of the reflective insulating layer at the convex position and the thickness of the reflective insulating layer at the concave position is 0.5 to 2 micrometers.

11. The solar cell according to claim 1, characterized in that, Both the first doped layer and the second doped layer are located on the back side, and the reflective insulating layer covers at least a portion of the first doped layer and / or the second doped layer.

12. The solar cell according to claim 11, characterized in that, The reflective insulating layer covers a portion of at least one of the first electrode and the second electrode.

13. The solar cell according to claim 11 or 12, characterized in that, The back side of the silicon wafer also includes an isolation region disposed between the first doped layer and the second doped layer, and the reflective insulating layer covers at least a portion of the isolation region.

14. The solar cell according to claim 13, characterized in that, Also includes: A first passivation layer is disposed on the back side, the first passivation layer being at least disposed between the reflective insulating layer and the first doped layer and between the reflective insulating layer and the second doped layer, the first electrode passing through the first passivation layer and contacting the first doped layer, and the second electrode passing through the first passivation layer and contacting the second doped layer.

15. The solar cell according to claim 14, characterized in that, The first passivation layer covers the isolation region, and the reflective insulating layer covers the first passivation layer on the isolation region.

16. The solar cell according to claim 1, characterized in that, The first doped layer is located on the back side, the second doped layer is located on the front side, and the reflective insulating layer covers the first doped layer.

17. The solar cell according to claim 16, characterized in that, The first doped layer is continuously disposed on the back surface; or, the first doped layer is intermittently disposed on the back surface, with a gap region between adjacent first doped layers, and the reflective insulating layer covers at least a portion of the gap region.

18. The solar cell according to claim 17, characterized in that, Also includes: A first passivation layer is disposed on the back side, the first passivation layer being at least disposed between the reflective insulating layer and the first doped layer, and the first electrode passes through the first passivation layer and contacts the first doped layer.

19. The solar cell according to claim 18, characterized in that, The first passivation layer covers the spacer region, and the reflective insulating layer covers the first passivation layer on the spacer region.

20. The solar cell according to any one of claims 16 to 19, characterized in that, The reflective insulating layer covers a portion of the first electrode.

21. A battery assembly, characterized in that, Including the solar cell as described in any one of claims 1 to 20.

22. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 21.

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