Photovoltaic module and method for manufacturing the same

Abstract

The present invention provides a photovoltaic module that can achieve a high light confinement effect and a method for manufacturing the same. [Solution] The photovoltaic module 1 is generally configured to include a substrate 2 that transmits light 9, an uneven surface 20 of the substrate 2 consisting of a plurality of peaks 23 and a plurality of valleys 24, an uneven portion 25 having no sharp angles on its edges 26, and a transparent electrode 3 formed along the uneven shape of the uneven portion 25. In this photovoltaic module 1, the uneven portion 25 is directly provided on the substrate 2 and the edges 26 of the uneven portion 25 do not have sharp angles, so compared to cases where this configuration is not adopted, defects in the uneven portion 25 are less likely to occur, and a high light confinement effect can be obtained.

Description

Technical Field

[0001] The present invention relates to a photovoltaic module and a method for manufacturing the same.

Background Art

[0002] As a conventional technique, a film substrate for a thin-film solar cell having a fine concavo-convex shape in which regular polyhedral pyramid shapes are spread without gaps is known (see, for example, Patent Document 1).

[0003] This fine concavo-convex shape is formed by pressing a mold against a photocurable or thermosetting resin composition provided on a film substrate for a thin-film solar cell.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since a conventional film substrate for a thin-film solar cell has a layer structure of a film substrate for a thin-film solar cell and a photocurable or thermosetting resin composition, it is difficult to control the shape and size of the concavo-convex portions having a polyhedral pyramid shape, and defects occur near the apexes of the concavo-convex portions and the bottom points which are the lowest points of the bottom surfaces, and there is a possibility that voids are generated between the electrode layers formed thereon, resulting in a reduction in the light confinement effect.

[0006] Therefore, an object of the present invention is to provide a photovoltaic module capable of obtaining a high light confinement effect and a method for manufacturing the same.

Means for Solving the Problems

[0007] One aspect of the present invention provides a photovoltaic module comprising a light-transmitting substrate, an uneven surface of the substrate formed as a surface shape consisting of a plurality of peaks and a plurality of valleys, with no sharp angles on the edges, and a transparent electrode formed along the uneven shape of the uneven surface.

[0008] Another aspect of the present invention provides a method for manufacturing a photovoltaic module, which involves preparing a light-transmitting substrate, pressing a mold having an uneven shape onto the surface of the substrate to transfer the uneven shape of the mold, thereby forming an uneven surface on the substrate consisting of multiple peaks and multiple valleys, with no sharp angles on the edges, and forming transparent electrodes along the uneven shape of the formed uneven surface.

[0009] Furthermore, another aspect of the present invention provides a method for manufacturing a photovoltaic module, which involves preparing a light-transmitting substrate, blowing particulate powder onto the surface of the substrate to form an uneven surface shape consisting of multiple peaks and multiple valleys, where the edges do not have sharp angles, and forming transparent electrodes along the uneven shape of the formed uneven surface. [Effects of the Invention]

[0010] According to the present invention, a high light confinement effect can be obtained. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is an example of a cross-sectional view of a photovoltaic module according to an embodiment. [Figure 2] Figure 2 is a perspective view showing an example of the uneven surface of a photovoltaic module according to an embodiment. [Figure 3] Figure 3 is an example of a cross-sectional view of a substrate on which a transparent electrode of a photovoltaic module according to an embodiment is provided, as seen from the direction of the arrow, when the substrate is cut along line AA in Figure 2. [Figure 4]Figure 4(a) is a diagram illustrating an example of the curvature of the peak portion of a photovoltaic module according to an embodiment, Figure 4(b) is a diagram illustrating an example of the curvature of the valley portion, and Figure 4(c) is a diagram illustrating an example of the distance from the reference plane to the peak of the peak portion and the bottom of the valley portion. [Figure 5] Figures 5(a) to 5(c) show examples of uneven surfaces in a modified photovoltaic module. [Figure 6] Figures 6(a) to 6(c) show examples of uneven surfaces in a modified photovoltaic module. [Figure 7] Figures 7(a) to 7(d) show an example of a method for manufacturing a photovoltaic module according to an embodiment. [Modes for carrying out the invention]

[0012] (Summary of the embodiment) The photovoltaic module according to this embodiment is generally configured to include a light-transmitting substrate, an uneven surface shape formed on the substrate consisting of multiple peaks and multiple valleys, with no sharp angles on the edges, and transparent electrodes formed along the uneven shape of the uneven surface.

[0013] Another embodiment of the method for manufacturing a photovoltaic module includes preparing a light-transmitting substrate, pressing a mold having an uneven shape onto the surface of the substrate to transfer the uneven shape of the mold, thereby forming an uneven surface on the substrate consisting of multiple peaks and multiple valleys, with no sharp angles on the edges, and forming transparent electrodes along the uneven shape of the formed uneven surface.

[0014] Furthermore, a method for manufacturing a photovoltaic module according to another embodiment of the present invention includes preparing a light-transmitting substrate, blowing particulate powder onto the surface of the substrate to form an uneven surface shape consisting of multiple peaks and multiple valleys, where the edges do not have sharp angles, and forming transparent electrodes along the uneven shape of the formed uneven surface.

[0015] In this photovoltaic module and its manufacturing method, since the concavo-convex portions are directly provided on the substrate and the ridge lines of the concavo-convex portions do not have sharp corners, compared with the case where this configuration is not adopted, defects are less likely to occur in the concavo-convex portions, and a high light confinement effect can be obtained.

[0016] [Embodiment] (Overview of Photovoltaic Module 1) FIG. 1 is an example of a cross-sectional view of a photovoltaic module according to an embodiment. FIG. 2 is a perspective view showing an example of the concavo-convex portions of the photovoltaic module according to the embodiment. FIG. 3 is an example of a cross-sectional view seen from the arrow direction of a cross-section obtained by cutting the substrate provided with the transparent electrode of the photovoltaic module according to the embodiment along the line A-A in FIG. 2. FIG. 4(a) is a diagram for explaining an example of the curvature of the peak portion of the photovoltaic module according to the embodiment, FIG. 4(b) is a diagram for explaining an example of the curvature of the valley portion, and FIG. 4(c) is a diagram for explaining an example of the distance from the reference plane to the apex of the peak portion and the bottom of the valley portion.

[0017] In each of the figures according to the embodiments described below, the ratios and shapes between the figures may be different from the actual ratios and shapes. Also, "A~B" indicating a numerical range is used to mean A or more and B or less. Hereinafter, the overview of the photovoltaic module 1 will be described.

[0018] As shown in FIGS. 1 to 3, the photovoltaic module 1 generally includes a substrate 2 that transmits light 9, a concavo-convex portion 25 formed as a concavo-convex shape on the surface 20 of the substrate 2 composed of a plurality of peak portions 23 and a plurality of valley portions 24 and having no sharp corners on the ridge line 26, and a transparent electrode 3 formed along the concavo-convex shape of the concavo-convex portion 25.

[0019] The photovoltaic module 1 is an organic solar cell, a silicon solar cell, a compound solar cell, an organic-inorganic hybrid solar cell, or the like. The photovoltaic module 1 of the present embodiment is, as an example, a perovskite solar cell. As shown in FIG. 2, the peak portions 23 and the valley portions 24 are provided continuously alternately or randomly.

[0020] As an example, the photovoltaic module 1 of this embodiment is generally configured to include the above-described substrate 2, a transparent electrode 3 provided on the substrate, a photoelectric conversion layer 4 provided on the transparent electrode 3 and converting the light energy of light 9 incident from the back surface 21 of the substrate 2 into electrical energy, and an upper electrode 5 provided on the photoelectric conversion layer 4. At least the transparent electrode 3, the photoelectric conversion layer 4, and the upper electrode 5 of the photovoltaic module 1 are sealed. As an example, the photovoltaic module 1 may also be configured to include multiple photovoltaic elements, each consisting of at least the transparent electrode 3, the photoelectric conversion layer 4, and the upper electrode 5.

[0021] As shown in Figures 4(a) and 4(b), the uneven portion 25 has curvature at least one of the highest point of the peak portion 23, which is the vertex 230, and the lowest point of the valley portion 24, which is the base point 240.

[0022] The peak 230 of the peak 23 and the base 240 of the valley 24 in this embodiment have curvature, as shown in Figures 4(a) to 4(c). The radius of curvature R1 shown in Figure 4(a) represents the radius of curvature at the peak 230 of the peak 23. The radius of curvature R3 shown in Figure 4(b) represents the radius of curvature at the base 240 of the valley 24. Having curvature means that the radii of curvature R1 and R3 are greater than zero.

[0023] Furthermore, the solid curves shown in Figure 4(c) represent the ridges 26 of the uneven portions 25. These ridges 26 are curves that pass through the peaks 230 of the peaks 23 and the bottom points 240 of the valleys 24, and connect the outer shape of the cross-section obtained by cutting with a plane perpendicular to the surface 20 of the substrate 2.

[0024] The peaks 23 and valleys 24 are separated by the reference plane 22 of the substrate 2, as shown in Figure 4(c) as an example. The ridge line 26 is, as an example, a curve formed by connecting the peak ridge line 26a of the peaks 23 and the valley ridge line 26b of the valleys 24. The reference plane 22 is, as an example, a plane that includes the center heights of the peaks 23 and valleys 24 and is parallel to the surface 20 of the substrate 2 before processing. The center height in this embodiment is, as an example, the height at which the first distance L1 from the reference plane 22 to the apex 230 of the peaks 23 and the second distance L2 from the reference plane 22 to the bottom point 240 of the valleys 24 are equal. If there is variation in the heights of the peaks 23 and valleys 24, the center height can be determined using, for example, an arithmetic mean or a weighted mean.

[0025] In this embodiment, the uneven surface 25 is, for example, tangentially continuous along its ridges 26. This tangential continuity means that the tangents at the endpoint 260 where the mountain ridge 26a and the valley ridge 26b connect coincide. In other words, tangential continuity means that the differential value at endpoint 260 of the mountain ridge 26a coincides with the differential value at endpoint 260 of the valley ridge 26b.

[0026] (Configuration of circuit board 2) Substrate 2 is, for example, a substrate formed using a transparent resin material such as acrylic, PET (Polyethylene Terephthalate), polycarbonate, polyethersulfone, fluorine film, or triacetate, but is not limited thereto. In this embodiment, substrate 2 is a film substrate using PET, which has excellent flexibility and high transparency. Furthermore, the upper part of substrate 2 may be more easily deformed than the lower part.

[0027] The substrate 2 has a thickness of 200 to 700 μm, for example. In this embodiment, the substrate 2 has a thickness of 300 μm, for example. The substrate 2 may also have a configuration in which multiple layers are stacked.

[0028] (Configuration of transparent electrode 3) The transparent electrode 3 is formed from a substantially transparent transparent conductive oxide (TCO) to allow light 9 incident from the substrate 2 side to be incident on the photoelectric conversion layer 4, as shown in Figure 1, for example. Such conductive materials include metal oxides, transparent conductive polymers, transparent conductive inks, and transparent conductive glass (FTO: Fluorine-doped tin oxide). Metal oxides include, for example, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO2), and titanium oxide (TiO2), which extract the current generated in the photoelectric conversion layer 4. Transparent conductive polymers include, for example, PEDOT / PSS (poly-3,4-ethylenedioxythiophene / polysulfonic acid). Transparent conductive inks include, for example, those containing carbon nanotubes and silver nanofibers in a binder.

[0029] The transparent electrode 3, for example, has a film thickness of 0.05 to 200 μm, preferably 30 μm.

[0030] The transparent electrode 3 in this embodiment is, for example, a transparent electrode made of indium tin oxide (ITO), but is not limited to this.

[0031] (Configuration of the photoelectric conversion layer 4) As described above, the photoelectric conversion layer 4 is configured to convert the light energy of the light 9 incident from the substrate 2 side into electrical energy.

[0032] (Configuration of upper electrode 5) The upper electrode 5 is formed from a conductive material such as gold, silver, aluminum, and copper. The upper electrode 5 is formed using gold as an example, but is not limited to this. For example, when light is taken in from the upper electrode 5 side, this upper electrode 5 may be configured as a transparent electrode.

[0033] (Regarding the uneven surface 25 of substrate 2) As shown in Figure 4(c), the distance L of the adjacent peak 23 and valley 24 is within a predetermined distance range, which is the sum of the first distance L1 from the vertex 230 of the adjacent peak 23 to the reference plane 22 and the second distance L2 from the bottom point 240 of the valley 24 to the reference plane 22.

[0034] This distance range is, for example, 0.2 to 5.0 μm, and more preferably 0.3 to 1.2 μm. In this embodiment, the peaks 23 and valleys 24 are 0.3 μm ≤ L1 + L2 ≤ 1.2 μm. The distance range is such that if there is no variation in the distances of the peaks 23 and valleys 24 from the reference plane 22, and the first distance L1 and the second distance L2 are equal, the distance L between the vertex 230 and the base point 240 will be 2L1 or 2L2. For example, about 10 different variations in distance L may be intentionally created.

[0035] Furthermore, as shown in Figure 4(c), the first interval P1 between the vertices 230 of adjacent peaks 23 and the second interval P2 between the base points 240 of adjacent valleys 24 are both within a predetermined interval range.

[0036] This spacing range is, for example, 0.2 to 6.0 μm, and more preferably 0.3 to 1.2 μm. In this embodiment, for example, the first spacing P1 and the second spacing P2 are equal. Note that variations in spacing, for example, around 10 different values, may be intentionally created.

[0037] Furthermore, it is preferable that the number obtained by dividing the height of adjacent peaks 23 and valleys 24 (L1+L2) by the width of the peaks 23 (second spacing P2) and the width of the valleys 24 (first spacing P1) is less than 1. In other words, it is preferable that the uneven portion 25 is formed such that at least one of the following conditions is met: [(L1+L2) / P1]<1 and [(L1+L2) / P2]<1.

[0038] (Regarding variations) Figures 5(a) to 6(c) show examples of uneven surfaces in a modified photovoltaic module.

[0039] Figure 5(a) shows a modified example in which the vertex 230 of the peak 23 and the base 240 of the valley 24 have no curvature, that is, the peak 23 and valley 24 have a conical shape. The first angle at the vertex 230 of the peak 23 is θ1. The second angle at the base 240 of the valley 24 is θ2. These first angle θ1 and second angle θ2 are not acute angles but obtuse angles, that is, angles within the angular range of 90° < θ1 and θ2 < 180°.

[0040] Figure 5(b) shows a modified example in which, as an example, at least a portion of the first distance L1 from the vertex 230 of the peak section 23 to the reference plane 22 is different, at least a portion of the second distance L2 from the base point 240 of the valley section 24 to the reference plane 22 is different, and the first interval P1 between the vertices 230 is the same, and the second interval P2 between the base points 240 is the same. The first distance L1 varies from vertex 230 to vertex 230. The second distance L2 also varies from base point 240 to base point 240. This variation indicates a state in which both identical and different distances are mixed. Note that the vertices 230 and base points 240 do not have curvature.

[0041] Figure 5(c) shows a modified example in which the first distance L1 from the vertex 230 of the peak section 23 to the reference plane 22 is the same, the second distance L2 from the base point 240 of the valley section 24 to the reference plane 22 is the same, and at least a portion of the first interval P1 between the vertices 230 is different, and at least a portion of the second interval P2 between the base points 240 is different. The first interval P1 varies for each adjacent vertex 230. The second interval P2 also varies for each adjacent base point 240. Note that the vertices 230 and base points 240 do not have curvature.

[0042] Figure 6(a) shows a modified example in which, as an example, at least a portion of the first distance L1 from the vertex 230 of the peak 23 to the reference plane 22 is different, at least a portion of the second distance L2 from the bottom point 240 of the valley 24 to the reference plane 22 is different, and the first interval P1 between the vertices 230 and the second interval P2 between the bottom points 240 are the same. The first distance L1 varies from vertex 230 to vertex 230. The second distance L2 also varies from bottom point 240 to bottom point 240. The vertices 230 and bottom points 240 have curvature.

[0043] Figure 6(b) shows a modified example in which the first distance L1 from the vertex 230 of the peak section 23 to the reference plane 22 is the same, the second distance L2 from the base point 240 of the valley section 24 to the reference plane 22 is the same, and at least a portion of the first interval P1 between the vertices 230 and at least a portion of the second interval P2 between the base points 240 are different. The first interval P1 varies for each adjacent vertex 230. The second interval P2 also varies for each adjacent base point 240. The vertices 230 and base points 240 have curvature.

[0044] Figure 6(c) shows an example of a modified example in which the curvature of the uneven portion 25 and the curvature of the transparent electrode 3 are different.

[0045] As shown in Figures 4(a), 4(b), and 6(c), the curvature of the transparent electrode 3 at the first point 31 corresponding to the apex 230 of the peak 23, and the curvature of the second point 32 corresponding to the bottom point 240 of the valley 24 are smaller than the curvature of the apex 230 of the peak 23, and the curvature of the bottom point 240 of the valley 24.

[0046] The curvature of the peak 230 of the peak 23 is, for example, the reciprocal of the radius of curvature R1, as shown in Figure 4(a). Similarly, the curvature of the base 240 of the valley 24 is, for example, the reciprocal of the radius of curvature R3, as shown in Figure 4(b).

[0047] The curvature of the first point 31 of the transparent electrode 3 is, for example, the reciprocal of the radius of curvature R2, as shown in Figure 4(a). As shown in Figure 4(a), the radius of curvature R2 is greater than the radius of curvature R1. In other words, the curvature of the first point 31 is less than the curvature of the vertex 230, and the curve is gentle.

[0048] Furthermore, the curvature of the second point 32 of the transparent electrode 3 is, for example, the reciprocal of the radius of curvature R4, as shown in Figure 4(b). As shown in Figure 4(b), the radius of curvature R4 is larger than the radius of curvature R3. In other words, the curvature of the second point 32 is smaller than the curvature of the base point 240, and the curve is gentle.

[0049] The photovoltaic module 1 may be configured by combining the above embodiments and modified examples.

[0050] (Manufacturing method for photovoltaic module 1) An example of a manufacturing method for the photovoltaic module 1 of this embodiment will be described below with reference to Figure 7.

[0051] As shown in Figure 7(a), a light-transmitting substrate 2 is prepared.

[0052] Next, as shown in Figure 7(b), the mold 6 having the uneven shape 60 is pressed onto the surface 20 of the substrate 2 to transfer the uneven shape 60 of the mold 6, thereby forming an uneven surface 25 on the surface 20 of the substrate 2 consisting of multiple peaks 23 and multiple valleys 24, with the edges 26 not having sharp angles. After formation, as shown in Figure 7(c), the mold 6 is removed from the substrate 2.

[0053] Next, as shown in Figure 7(d), a transparent electrode 3 is formed along the uneven shape of the formed uneven portion 25. Subsequently, a photoelectric conversion layer 4 and an upper electrode 5 are formed to obtain a photovoltaic module 1.

[0054] Furthermore, a method for manufacturing a photovoltaic module 1 according to another embodiment includes preparing a light-transmitting substrate 2, blowing particulate powder onto the surface 20 of the substrate 2 to form an uneven surface 25 consisting of a plurality of peaks 23 and a plurality of valleys 24, where the edges 26 do not have sharp angles, and forming a transparent electrode 3 along the uneven shape of the formed uneven surface 25.

[0055] The manufacturing method for this photovoltaic module 1 involves using a sputtering method or the like to blow particulate powder onto the surface 20 of the substrate 2, thereby forming uneven surfaces 25 that do not have sharp angles on the edges 26.

[0056] (Effects of the embodiment) The photovoltaic module 1 according to this embodiment can achieve a high light confinement effect. Specifically, in the photovoltaic module 1, the uneven portion 25 is directly provided on the substrate 2, and the edges 26 of the uneven portion 25 do not have sharp angles. Therefore, compared to a configuration that does not employ this design, defects in the uneven portion 25 are less likely to occur, and a high light confinement effect can be achieved.

[0057] Since the photovoltaic module 1 forms an uneven surface on the substrate 2, positional misalignment with the mold 6 is less likely to occur compared to forming an uneven surface on a component on the substrate, and the uneven surface can be formed in micrometer units rather than nanometer units. Furthermore, because the photovoltaic module 1 has an uneven surface in micrometer units, a higher light confinement effect can be obtained compared to an uneven surface in nanometer units.

[0058] Since the photovoltaic module 1 forms an uneven surface on the substrate 2, it becomes easier to control the size and shape of the uneven surface compared to a configuration that does not employ this design.

[0059] Since the photovoltaic module 1 does not have any sharp angles on its edges 26, it is easier to remove the mold 6 and substrate 2 compared to the case where there are sharp angles, and damage during removal is less likely to occur. Also, because the photovoltaic module 1 does not have any sharp angles, cavities are less likely to form between the substrate 2 and the transparent electrode 3, and a higher light confinement effect can be obtained.

[0060] In the photovoltaic module 1, the sum of the first distance L1 from the peak 230 of the peak 23 to the reference plane 22 and the second distance L2 from the bottom point 240 of the valley 24 to the reference plane 22 is deliberately given a regular variation within the distance range. Therefore, compared to a configuration that does not employ this approach, a stable and high conversion efficiency can be obtained even if deviations occur. Furthermore, because the photovoltaic module 1 deliberately has multiple distances L set, it can be manufactured with higher overall precision and stability compared to a configuration that does not employ this approach.

[0061] In the manufacturing method of the photovoltaic module 1, the uneven shape can be formed by transferring the uneven shape of the mold 6, so compared to cases using etching methods, etc., size control is easier and manufacturing costs can be reduced.

[0062] Although several embodiments and modifications of the present invention have been described above, these embodiments and modifications are merely examples and do not limit the invention as defined in the claims. These novel embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Furthermore, not all combinations of features described in these embodiments and modifications are necessarily essential for solving the problem of the invention. Moreover, these embodiments and modifications are included in the scope and spirit of the invention, as well as in the invention described in the claims and its equivalents. [Explanation of Symbols]

[0063] 1…Photovoltaic module, 2…Substrate, 3…Transparent electrode, 4…Photoelectric conversion layer, 5…Upper electrode, 6…Mold, 9…Light, 20…Front surface, 21…Back surface, 22…Reference plane, 23…Peak, 24…Valley, 25…Rump, 26…Ridge, 26a…Peak ridge, 26b…Valley ridge, 31…First point, 32…Second point, 60…Rump shape, 230…Vertex, 240…Bottom point, 260…Endpoint

Claims

1. A light-transmitting substrate, The surface of the substrate is formed as an uneven shape consisting of multiple peaks and multiple valleys, and the uneven portion does not have sharp angles on its ridges, A transparent electrode formed along the uneven shape of the uneven portion, A photovoltaic module equipped with this module.

2. The aforementioned uneven portion has curvature at at least one of the highest point of the peak and the lowest point of the valley. The photovoltaic module according to claim 1.

3. The aforementioned uneven portion has a peak which is the highest point of the peak and a bottom which is the highest point of the valley, The aforementioned peak and valley are such that the sum of the first distance from the apex of the adjacent peak to the reference plane and the second distance from the bottom of the valley to the reference plane is within a predetermined distance range. The photovoltaic module according to claim 1.

4. The aforementioned uneven portion has a peak which is the highest point of the peak and a bottom which is the highest point of the valley, The aforementioned peaks and valleys are such that the first distance between the vertices of adjacent peaks and the second distance between the bottoms of adjacent valleys are both within a predetermined interval range. The photovoltaic module according to claim 1.

5. The transparent electrode is configured such that the curvature of the first point corresponding to the peak of the peak and the curvature of the second point corresponding to the bottom of the valley are smaller than the curvature of the peak of the peak and the curvature of the bottom of the valley. A photovoltaic module according to any one of claims 2 to 4.

6. Prepare a light-transmitting substrate, By pressing a mold having an uneven shape onto the surface of the substrate and transferring the uneven shape of the mold, an uneven surface is formed on the substrate consisting of a plurality of peaks and a plurality of valleys, and the edges do not have sharp angles. A transparent electrode is formed along the shape of the uneven surface of the formed uneven portion. A method for manufacturing photovoltaic modules.

7. Prepare a light-transmitting substrate, By blowing particulate powder onto the surface of the substrate, an uneven surface shape is formed on the substrate, consisting of multiple peaks and multiple valleys, where the edges do not have sharp angles. A transparent electrode is formed along the shape of the uneven surface of the formed uneven portion. A method for manufacturing photovoltaic modules.

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