A back contact cell, cell assembly and photovoltaic system

Abstract

This utility model relates to the field of solar cell technology, specifically disclosing a back-contact battery, a battery module, and a photovoltaic system. The back-contact battery includes: a substrate having a front side and a back side, with the back side having a plurality of alternating first and second regions; an anti-reflection layer disposed on the front side, with the side of the anti-reflection layer facing away from the substrate having a first textured surface with unevenness; and a TCO layer including a first TCO segment and a second TCO segment, the first TCO segment being disposed in the first region, the second TCO segment being disposed in the second region, and the side of the second TCO segment facing away from the substrate having a second textured surface with unevenness; the first textured surface includes a plurality of first protruding units protruding in the direction facing away from the substrate, and the second textured surface includes a plurality of second protruding units protruding in the direction facing away from the substrate, the average height of the first protruding units being greater than the average height of the second protruding units, and the average width of the first protruding units being greater than the average width of the second protruding units. Through the adaptive textured surface design of the front and back surfaces of the battery, light absorption is effectively increased, optical loss is reduced, and the battery conversion efficiency is further improved.

Description

Technical Field

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

[0002] Back-contact solar cells have the advantage of having an effective area without grid lines blocking the front side. Therefore, compared with traditional solar cells where the positive and negative electrodes are respectively located on the front and back sides of the cell, back-contact cells have the characteristics of high light utilization, high short-circuit current, and high open-circuit voltage.

[0003] Currently, to improve the light utilization rate of batteries, textured surfaces of similar size are often prepared on the front and back sides of silicon wafers, and anti-reflection material layers are deposited. For example, an anti-reflection layer with anti-reflection effect is deposited on the front side, and a transparent conductive layer with both conductivity and anti-reflection effect is deposited on the back side. This anti-reflection design ignores the difference in anti-reflection principle between the front and back sides due to their different locations, resulting in limited anti-reflection effect of existing back contact batteries, which limits further improvement of the performance of back contact batteries. Utility Model Content

[0004] The purpose of this invention is to provide a back contact battery, battery module and photovoltaic system in light of the existing technology.

[0005] The back-contact battery of this invention effectively increases light absorption and reduces optical loss through an adaptive textured surface design on the front and back surfaces of the battery, thereby increasing the battery short-circuit current and further improving the battery conversion efficiency.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] First, this utility model provides a back contact battery, comprising:

[0008] The substrate has a front side and a back side disposed opposite to each other, and the back side has a plurality of alternating first regions and second regions;

[0009] An anti-reflective layer is disposed on the front side, and the side of the anti-reflective layer facing away from the substrate has a first textured surface with uneven surfaces;

[0010] The TCO layer includes a first TCO segment and a second TCO segment. The first TCO segment is disposed in the first region, and the second TCO segment is disposed in the second region. The side of the second TCO segment facing away from the substrate has a second textured surface with uneven surfaces.

[0011] The first textured surface includes a plurality of first protrusion units that protrude in a direction away from the substrate, and the second textured surface includes a plurality of second protrusion units that protrude in a direction away from the substrate. The average height of the first protrusion units is greater than the average height of the second protrusion units, and the average width of the first protrusion units is greater than the average width of the second protrusion units.

[0012] In some embodiments, the thickness of the antireflective layer is 0.3 μm to 1 μm.

[0013] In some embodiments, the thickness of the TCO layer is 1 μm to 5 μm.

[0014] In some embodiments, the front side has a first undulating pile structure, and the back side located in the second region has a second undulating pile structure. The first pile structure includes a plurality of first textured units that protrude in a direction away from the substrate, and the second pile structure includes a plurality of second textured units that protrude in a direction away from the substrate. The average height of the first textured units is greater than the average height of the second textured units, and the average width of the textured unit is greater than the average width of the second textured unit.

[0015] In some embodiments, the first region is an N-type conductive region and the second region is a P-type conductive region.

[0016] In some embodiments, it also includes:

[0017] A first semiconductor composite layer is disposed in the first region, comprising a first passivation layer and a first doped layer sequentially disposed along a direction away from the substrate;

[0018] The second semiconductor composite layer, at least partially disposed in the second region, includes a second passivation layer and a second doped layer sequentially disposed along a direction away from the substrate, wherein the polarity of the second doped layer is opposite to that of the first doped layer;

[0019] At least a portion of the first TCO segment is electrically connected to the side of the first doped layer opposite to the substrate, and at least a portion of the second TCO segment is electrically connected to the side of the second doped layer opposite to the substrate.

[0020] In some embodiments, the TCO layer may be a single-layer material layer or a composite material layer formed by stacking multiple single-layer material layers.

[0021] In some embodiments, the single-layer material layer is any one of ITO layer, IWO layer, and AZO layer.

[0022] Secondly, this utility model also provides a battery assembly, including the aforementioned back contact battery.

[0023] Furthermore, this utility model also provides a photovoltaic system, including the aforementioned battery module.

[0024] The beneficial effects of this utility model are as follows:

[0025] In this invention, the side of the antireflective layer facing away from the substrate (on the front surface of the battery) is set as a first textured surface with unevenness, and the side of the second TCO segment facing away from the substrate (on the back surface of the battery) is set as a second textured surface with unevenness, and the first protrusion unit of the first textured surface is larger than the second protrusion unit of the second textured surface in terms of both average height and average width.

[0026] On the one hand, the front of the battery, as the main incident surface for light, has an abundant light source. Placing a first protruding unit with a larger average height and width at this location better accommodates long-wavelength light, especially infrared light, making it easier to form a significant optical path difference and resulting in better interference. This allows more infrared light to enter the battery, effectively reducing infrared light reflection loss and increasing the proportion of light entering the battery. Simultaneously, the first protruding unit provides a larger effective light-receiving area, offering more opportunities for light incidence and improving light absorption efficiency. On the other hand, on the back of the solar cell, the light acting on it mainly propagates from inside the battery, and the light intensity is relatively weak. Therefore, placing a second protruding unit with a smaller average height and width at this location, compared to a protruding unit with a larger average height and width, results in a more orderly scattering and reflection path, simpler interference phenomena, and easier reintroduction of light into the battery, achieving secondary light utilization and better reducing optical losses.

[0027] Therefore, this utility model effectively increases light absorption and reduces optical loss by adapting the textured surface design of the front and back surfaces of the battery, thereby increasing the battery short-circuit current and further improving the battery conversion efficiency. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the back contact battery of this utility model.

[0029] Figure 2 for Figure 1 A magnified view of a portion of the image. Detailed Implementation

[0030] 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.

[0031] In the description of this utility model, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," etc., may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "multiple" or "several" means two or more, unless otherwise explicitly specified.

[0032] In the description of this utility model, unless otherwise expressly specified and limited, the first feature "above" or "below" the second feature may include the first feature and the second feature being in direct contact, or the first feature and the second feature not being in direct contact but being in contact through another feature between them.

[0033] First, see Figure 1 and Figure 2 As shown, this utility model provides a back contact battery, comprising:

[0034] The substrate 1 has a front side 11 and a back side 12 disposed opposite to each other, and the back side 12 has a plurality of alternating first regions and second regions;

[0035] An anti-reflection layer 2 is disposed on the front side 11, and the side of the anti-reflection layer 2 facing away from the substrate 1 has a first textured surface 21 with uneven texture.

[0036] TCO layer 3, TCO layer 3 includes a first TCO segment 31 and a second TCO segment 32. The first TCO segment 31 is disposed in a first region, the second TCO segment 32 is disposed in a second region, and the side of the second TCO segment 32 facing away from the substrate 1 has a second textured surface 33 with uneven surface.

[0037] The first textured surface 21 includes a plurality of first protrusion units 211 protruding in a direction away from the substrate 1, and the second textured surface 33 includes a plurality of second protrusion units 331 protruding in a direction away from the substrate 1. The average height H1 of the first protrusion units 211 is greater than the average height H2 of the second protrusion units 331, and the average width W1 of the first protrusion units 211 is greater than the average width W2 of the second protrusion units 331.

[0038] Understandably, the substrate 1 has a light-receiving surface (front side 11) and a back-lighting surface (back side 12) arranged opposite to each other, wherein the light-receiving surface generally refers to the side that receives light. It should be noted that, in some embodiments, the back-lighting surface may also absorb light incident through the back-lighting surface, thereby generating photocurrent. In addition, the material of the substrate 1 may be silicon, such as monocrystalline silicon, microcrystalline silicon, polycrystalline silicon, or amorphous silicon, but is not limited to these.

[0039] The height refers to the relative distance between the highest point (the end away from the base 1) and the lowest point (the end close to the base 1) of the first protrusion unit 211 in the thickness direction of the base 1, and the width dimension refers to the size of the widest part of the projection of the first protrusion unit 211 onto a plane perpendicular to the thickness direction of the base 1.

[0040] In this invention, the side of the antireflective layer 2 facing away from the substrate 1 (on the surface of the front side 11 of the battery) is set as a first textured surface 21 with unevenness, and the side of the second TCO segment 32 facing away from the substrate 1 (on the surface of the back side 12 of the battery) is set as a second textured surface 33 with unevenness, and the first protrusion unit 211 of the first textured surface 21 is larger than the second protrusion unit 331 of the second textured surface 33 in terms of both average height and average width.

[0041] On the one hand, the front surface 11 of the battery serves as the main incident surface for light, with ample light source. The placement of a first protruding unit 211 with a larger average height and width at this location allows for better adaptation to long-wavelength light, especially infrared light, making it easier to form a significant optical path difference and resulting in better interference. This allows more infrared light to enter the battery, effectively reducing infrared light reflection loss and increasing the proportion of light entering the battery. Simultaneously, the first protruding unit 211 provides a larger effective light-receiving area, offering more opportunities for light incidence and improving light absorption efficiency. On the other hand, on the back surface 12 of the solar cell, the light acting on it mainly propagates from inside the battery, resulting in relatively weak light intensity. Therefore, a second protruding unit 331 with a smaller average height and width at this location, compared to the protruding unit with a larger average height and width, provides a more orderly scattering and reflection path, simpler interference phenomena, and easier reintroduction of light into the battery, enabling secondary utilization of light and better reducing optical losses.

[0042] Therefore, this utility model effectively increases light absorption and reduces optical loss by adapting the textured surface design of the front and back surfaces 12 of the battery, thereby increasing the battery short-circuit current and further improving the battery conversion efficiency.

[0043] In some embodiments, the TCO layer 3, namely the transparent conductive oxide thin film layer, can be a single-layer material layer or a composite material layer composed of multiple single-layer material layers stacked together. The material of the single-layer material layer can be any one of ITO, IWO, and AZO.

[0044] For example, the shapes of the first protrusion unit 211 and the second protrusion unit 331 can be independently pyramid-shaped, pyramid-like, pyramid-like, cone-like, etc., but are not limited to these.

[0045] In some embodiments, the thickness of the antireflective layer 2 is 0.3 μm to 1 μm.

[0046] For example, the thickness of the antireflection layer 2 is 0.3μm, 0.35μm, 0.4μm, 0.45μm, 0.5μm, 0.55μm, 0.6μm, 0.65μm, 0.7μm, 0.75μm, 0.8μm, 0.85μm, 0.9μm, 0.95μm, or 1μm, but is not limited thereto.

[0047] Within this range, it is possible to ensure that the antireflection layer 2 has a good broadband antireflection effect, while avoiding excessive absorption of light by the material layer itself due to excessive thickness, thereby further improving the utilization rate of light.

[0048] In some embodiments, the thickness of the TCO layer 3 is 1 μm to 5 μm.

[0049] For example, the thickness of the TCO layer 3 is 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm, but is not limited thereto.

[0050] When the thickness of TCO layer 3 is too thick, it can easily aggravate the light loss of the material layer itself and affect the secondary utilization of light. When the thickness of TCO layer 3 is too thin, it is difficult to fully exert the anti-reflection effect, which also affects the secondary utilization of light. At the same time, the resistance increases, the interface recombination loss increases, and the battery conversion efficiency is affected.

[0051] In some embodiments, see Figure 1 and Figure 2 As shown, the front side 11 has a first undulating pile structure, and the back side 12 has a second undulating pile structure in the second region. The first pile structure includes a plurality of first texture units 111 protruding in the direction away from the substrate 1, and the second pile structure includes a plurality of second texture units 121 protruding in the direction away from the substrate 1. The average height of the first texture unit 111 is greater than the average height of the second texture unit 121, and the average width of the texture unit is greater than the average width of the second texture unit 121.

[0052] This allows for the formation of a first textured surface 21 on the first textured surface and a second textured surface 33 on the second textured surface, thereby creating a compatible textured surface design on the front and back surfaces 12 of the battery. This effectively increases light absorption, reduces optical loss, and increases the battery short-circuit current, further improving the battery conversion efficiency.

[0053] Understandably, either the first region or the second region can be an N-type conductive region, and the other can be a P-type conductive region. Preferably, the first region is an N-type conductive region and the second region is a P-type conductive region. This results in the first TCO segment 31 located in the N-type conductive region having a relatively flat surface, which is conducive to the smooth transport of electrons. The second TCO segment 32 located in the P-type conductive region has a larger surface area than the flat surface, which is conducive to providing more collection sites for photogenerated holes, thereby improving the overall battery conversion efficiency.

[0054] In some embodiments, see Figure 1 and Figure 2 As shown, it also includes:

[0055] The first semiconductor composite layer 4 is disposed in the first region and includes a first passivation layer 41 and a first doped layer 42 sequentially disposed along the direction away from the substrate 1.

[0056] The second semiconductor composite layer 5 is at least partially disposed in the second region, including a second passivation layer 51 and a second doped layer 52 disposed sequentially along the direction away from the substrate 1, wherein the polarity of the second doped layer 52 is opposite to that of the first doped layer 42.

[0057] At least a portion of the first TCO segment 31 is electrically connected to the side of the first doped layer 42 facing away from the substrate 1, and at least a portion of the second TCO segment 32 is electrically connected to the side of the second doped layer 52 facing away from the substrate 1.

[0058] Understandably, in terms of conductivity type, the polarity of the first doped layer 42 and the second doped layer 52 can be the same as or opposite to the polarity of the substrate 1, as long as the polarity of the first doped layer 42 is opposite to that of the second doped layer 52. Either the first doped layer 42 and / or the second doped layer 52 is made of monocrystalline silicon, polycrystalline silicon, or amorphous silicon doped with group III elements (e.g., B, Ga, or In), and the other is made of monocrystalline silicon, microcrystalline silicon, polycrystalline silicon, or amorphous silicon doped with group V elements (e.g., P, As, Sb). In some embodiments, preferably, the second doped layer 52 is a P-type doped layer, the first doped layer 42 is an N-type doped layer, and the substrate 1 is N-type silicon.

[0059] For example, the first passivation layer 41 and the second passivation layer 51 may be intrinsic amorphous silicon layers or tunneling oxide layers (such as silicon oxide, titanium oxide, etc.), but are not limited thereto.

[0060] Understandably, the first TCO segment 31 and the first doped layer 42 can be electrically connected through direct contact or indirect contact through a conductive material layer. The contact can be a partial area of ​​the first TCO segment 31 in contact with the first doped layer 42, or the entire area of ​​the first TCO segment 31 in contact with the first doped layer 42. Similarly, the second TCO segment 32 and the second doped layer 52 can be electrically connected through direct contact or indirect contact through a conductive material layer. The contact can be a partial area of ​​the second TCO segment 32 in contact with the second doped layer 52, or the entire area of ​​the second TCO segment 32 in contact with the second doped layer 52.

[0061] In this embodiment, at least a portion of the second semiconductor composite layer 5 is disposed in the second region. That is, in some embodiments, the second semiconductor composite layer 5 may exist only in the second region. In this case, the first semiconductor composite layer 4 and the second semiconductor composite layer 5 do not have overlapping regions, and the first doped layer 42 and the second doped layer 52 are alternately arranged along a direction perpendicular to the thickness of the substrate 1 (i.e., the alternating arrangement direction of the first region and the second region). In some embodiments, see [reference needed]. Figure 1 and Figure 2As shown, the second semiconductor composite layer 5 may be a stacked region that extends to the first region and overlaps with the first semiconductor composite layer 4. In this case, an insulating protective layer 6 is provided between the stacked regions of the first semiconductor composite layer 4 and the second semiconductor composite layer 5 in the first region. For example, the insulating protective layer 6 may be made of phosphosilicate glass, but is not limited thereto.

[0062] For example, the antireflection layer 2 can be made of SiN. x Or SiO, but not limited to this.

[0063] In some embodiments, see Figure 1 As shown, a front passivation layer 7 is also provided between the antireflection layer 2 and the substrate 1. For example, the material of the front passivation layer 7 can be a-Si:H(i) or Al2O3, but is not limited to this.

[0064] Secondly, this utility model also provides a battery assembly, including the aforementioned back contact battery.

[0065] For example, the back contact battery may be an HBC battery, but is not limited to this.

[0066] Furthermore, this utility model also provides a photovoltaic system, including the aforementioned battery module.

[0067] Multiple battery modules can be connected in series or parallel through a junction box to form a photovoltaic system. This photovoltaic system can be used 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 use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, and solar buildings, but is not limited to these.

[0068] In the description of this specification, references to terms such as "some embodiments," "exemplary," "example," or "for example," 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 this application. 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.

[0069] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present utility model. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the scope of the present utility model shall still fall within the scope of the present utility model.

Claims

1. A back-contact battery, characterized in that, include: The substrate has a front side and a back side disposed opposite to each other, and the back side has a plurality of alternating first regions and second regions; An anti-reflective layer is disposed on the front side, and the side of the anti-reflective layer facing away from the substrate has a first textured surface with uneven surfaces; The TCO layer includes a first TCO segment and a second TCO segment. The first TCO segment is disposed in the first region, and the second TCO segment is disposed in the second region. The side of the second TCO segment facing away from the substrate has a second textured surface with uneven surfaces. The first textured surface includes a plurality of first protrusion units that protrude in a direction away from the substrate, and the second textured surface includes a plurality of second protrusion units that protrude in a direction away from the substrate. The average height of the first protrusion units is greater than the average height of the second protrusion units, and the average width of the first protrusion units is greater than the average width of the second protrusion units.

2. A back contact battery according to claim 1, characterized in that, The thickness of the antireflective layer is 0.3 μm to 1 μm.

3. A back contact battery according to claim 1, characterized in that, The thickness of the TCO layer is 1 μm to 5 μm.

4. A back contact battery according to claim 1, characterized in that, The front side has a first velvet structure with uneven surfaces, and the back side located in the second region has a second velvet structure with uneven surfaces. The first velvet structure includes a plurality of first textured units that protrude in the direction away from the substrate, and the second velvet structure includes a plurality of second textured units that protrude in the direction away from the substrate. The average height of the first textured unit is greater than the average height of the second textured unit, and the average width of the textured unit is greater than the average width of the second textured unit.

5. A back contact battery according to claim 1, characterized in that, The first region is an N-type conductive region, and the second region is a P-type conductive region.

6. A back contact battery according to claim 1, characterized in that, Also includes: A first semiconductor composite layer is disposed in the first region, comprising a first passivation layer and a first doped layer sequentially disposed along a direction away from the substrate; The second semiconductor composite layer, at least partially disposed in the second region, includes a second passivation layer and a second doped layer sequentially disposed along a direction away from the substrate, wherein the polarity of the second doped layer is opposite to that of the first doped layer; At least a portion of the first TCO segment is electrically connected to the side of the first doped layer opposite to the substrate, and at least a portion of the second TCO segment is electrically connected to the side of the second doped layer opposite to the substrate.

7. A back contact battery according to claim 1, characterized in that, The TCO layer can be a single-layer material layer or a composite material layer composed of multiple single-layer material layers stacked together.

8. A back contact battery according to claim 7, characterized in that, The single-layer material can be any one of ITO, IWO, or AZO.

9. A battery assembly, characterized in that, Includes a back contact battery according to any one of claims 1 to 8.

10. A photovoltaic system, characterized in that, Includes the battery assembly according to claim 9.

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