Solar cell modules and conversion devices

Abstract

A solar battery module (100) comprising a plurality of solar battery cells (110-1), (110-2), (110-3) each of which absorbs light in a set predetermined wavelength band and converts the light to electricity and a wavelength separation lens (120) which includes a transparent layer (140) which covers the plurality of solar battery cells (110-1), (110-2), (110-3) and a plurality of structures (150) which are arranged on the transparent layer (140) or in the transparent layer (140) in the surface direction of the transparent layer (140) at intervals equal to or shorter than the wavelength of the incident light and which are arranged such that the incident light is separated into the predetermined wavelength bands, the light separated into each predetermined wavelength band being focused onto the solar battery cell corresponding to each wavelength band.

Description

[Technical Field]

[0001] The present invention relates to a solar cell module and a conversion device. [Background technology]

[0002] Research and development into solar cells is progressing toward the realization of a carbon-neutral society. Conventionally, technologies have been developed to modularize and array solar cells with photoelectric conversion sections that use a single material (e.g., Si) for the photoelectric conversion of sunlight. In such solar cells that use only Si, only a portion of the wavelengths of incident light is converted into electricity due to the optical absorption spectrum resulting from the band gap of the material. Therefore, solar cells that use only Si are unable to efficiently absorb and photoelectrically convert all of the sunlight, which has a wide spectrum, due to the optical absorption spectrum resulting from the band gap of the material, limiting the efficiency of the module.

[0003] Therefore, a tandem solar cell has been proposed that uses a multi-junction compound semiconductor in which multiple materials with different bandgaps are stacked in the photoelectric conversion section, which efficiently absorbs and photoelectrically converts sunlight with a wide spectrum (Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] JF Geisz, RM France, KL Schulte, et al. “Six-junction III-V solar cells with 47.1% conversion efficiency under 143 Suns concentration”, Nat Energy 5, 326-335 (2020). [Retrieved December 20, 2022], Internet<URL:https: / / doi.org / 10.1038 / s41560-020-0598-5> Summary of the Invention [Problem to be solved by the invention]

[0005] However, tandem solar cells have a problem in that there is a limit to the materials that can be used as multi-junction compound semiconductors, and there is a limit to the improvement of photoelectric conversion efficiency.

[0006] The present invention has been made in view of the above, and an object of the present invention is to provide a solar cell module and a conversion device that can improve photoelectric conversion efficiency. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the solar cell module of the present invention is characterized by having a plurality of solar cells, each of which absorbs light in a predetermined wavelength band set for it and converts it into electricity, a transparent layer covering the plurality of solar cells, and an optical element having a plurality of structures arranged on or within the transparent layer in the surface direction of the transparent layer at a period equal to or less than the wavelength of the incident light, the plurality of structures being arranged so as to separate the incident light into each of the predetermined wavelength bands and concentrate the light on each of the solar cell cells corresponding to each wavelength band.

[0008] Furthermore, the conversion device according to the present invention is characterized by having the above-mentioned solar cell module, a secondary battery that stores power, and a power conversion unit that boosts the input voltage from the solar cell module and supplies it to the secondary battery. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a solar cell module and a conversion device that can improve photoelectric conversion efficiency. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a side view showing a schematic configuration of a conversion device according to an embodiment. [Figure 2]FIG. 2 is a diagram schematically illustrating an example of a cross section of a main part of a solar cell module according to an embodiment. [Figure 3] FIG. 3 is a diagram showing a schematic arrangement of solar cells when the solar cell module according to the embodiment is viewed from above. [Figure 4] FIG. 4 is a diagram showing an example of a cross section of the solar cell module when viewed from the side along line aa' in FIG. [Figure 5] FIG. 5 is a diagram showing an example of a cross section of the solar cell module when viewed from the side along the line bb' in FIG. [Figure 6] FIG. 6 is a diagram schematically showing the concentration of light onto the solar cell in the solar cell module shown in FIG. [Figure 7] FIG. 7 is a diagram schematically showing the concentration of light onto the solar cell in the solar cell module shown in FIG. [Figure 8] FIG. 8 is a diagram schematically showing the concentration of light onto the solar cell in the solar cell module shown in FIG. [Figure 9] FIG. 9 is a diagram schematically showing the concentration of light onto the solar cell in the solar cell module shown in FIG. [Figure 10] FIG. 10 is a diagram schematically showing the arrangement of solar cells when the solar cell module according to the embodiment is viewed from above. [Figure 11] FIG. 11 is a diagram showing an example of a cross section of the solar cell module when viewed from the side along the line cc′ in FIG. [Figure 12] FIG. 12 is a diagram schematically showing the concentration of light onto the solar cell in the solar cell module shown in FIG. [Figure 13] FIG. 13 is a diagram schematically showing the concentration of light onto the solar cell in the solar cell module shown in FIG. [Figure 14] FIG. 14 is a diagram schematically showing the concentration of light onto the solar cell in the solar cell module shown in FIG. [Figure 15] FIG. 15 is a diagram schematically illustrating another example of a part of a cross section of the wavelength separation lens according to the embodiment. [Figure 16] FIG. 16 is a diagram schematically illustrating another example of a part of a cross section of the wavelength separation lens according to the embodiment. [Figure 17] FIG. 17 is a diagram schematically illustrating another example of a part of a cross section of the wavelength separation lens according to the embodiment. [Figure 18] FIG. 18 is a diagram schematically illustrating another example of a part of a cross section of the wavelength separation lens according to the embodiment. [Figure 19] FIG. 19 is a diagram schematically illustrating another example of a part of a cross section of the wavelength separation lens according to the embodiment. [Figure 20] FIG. 20 is a diagram schematically illustrating another example of a part of a cross section of the wavelength separation lens according to the embodiment. [Figure 21] FIG. 21 is a diagram schematically illustrating another example of a part of a cross section of the wavelength separation lens according to the embodiment. [Figure 22] FIG. 22 is a diagram schematically illustrating another example of a part of a cross section of the wavelength separation lens according to the embodiment. [Figure 23] FIG. 23 is a diagram schematically illustrating another example of a part of a cross section of the wavelength separation lens according to the embodiment. [Figure 24] FIG. 24 is a diagram schematically illustrating another example of a part of a cross section of the wavelength separation lens according to the embodiment. [Figure 25] FIG. 25 is a diagram showing an example of a schematic configuration of the structure shown in FIG. [Figure 26] FIG. 26 is a diagram showing an example of a schematic configuration of the structure shown in FIG. [Figure 27] FIG. 27 is a diagram showing an example of a schematic configuration of the structure shown in FIG. [Figure 28] FIG. 28 is a diagram showing an example of a schematic configuration of the structure shown in FIG. [Figure 29] FIG. 29 is a diagram showing an example of a schematic configuration of the structure shown in FIG. [Figure 30] FIG. 30 is a diagram showing an example of a schematic configuration of the structure shown in FIG. [Figure 31] FIG. 31 is a diagram showing an example of a cross-sectional shape of the structure shown in FIG. [Figure 32]FIG. 32 is a diagram showing an ideal optical phase delay distribution when the center wavelength is 500 nm. [Figure 33] FIG. 33 is a diagram showing an ideal optical phase delay distribution when the center wavelength is 650 nm. [Figure 34] FIG. 34 is a diagram showing an ideal optical phase delay distribution when the center wavelength is 800 nm. [Figure 35] FIG. 35 is a diagram showing an ideal optical phase delay distribution when the center wavelength is 1000 nm. [Figure 36] FIG. 36 is a diagram showing an ideal optical phase delay distribution when the center wavelength is 500 nm. [Figure 37] FIG. 37 is a diagram showing an ideal optical phase delay distribution when the center wavelength is 650 nm. [Figure 38] FIG. 38 is a diagram showing an ideal optical phase delay distribution when the center wavelength is 1000 nm. [Figure 39] FIG. 39 is a diagram schematically showing an example of a cross section of a main part of a conventional solar cell module. [Figure 40] FIG. 40 is a diagram schematically showing the wavelength dependency of the intensity of light radiated / absorbed by the solar cell module shown in FIG. [Figure 41] FIG. 41 is a diagram schematically showing another example of a cross section of a main part of a conventional solar cell module. [Figure 42] FIG. 42 is a diagram schematically showing the wavelength dependency of the intensity of light radiated / absorbed by the solar cell module shown in FIG. [Figure 43] FIG. 43 is a diagram schematically showing the wavelength dependency of the intensity of light radiated / absorbed by the solar cell module shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] The best mode for carrying out the present invention will be described in detail below with reference to the drawings. Note that in the following description, each drawing merely shows a schematic representation of the shape, size, and positional relationship to the extent that the contents of the present invention can be understood, and therefore the present invention is not limited to the shape, size, and positional relationship exemplified in each drawing. Furthermore, in the description of the drawings, the same parts are designated by the same reference numerals.

[0012] [Embodiment Mode] [Conversion device] First, a conversion device according to an embodiment of the present invention will be described below. Fig. 1 is a block diagram illustrating a schematic configuration of a conversion device according to an embodiment.

[0013] For example, as shown in FIG. 1, a conversion device 10 according to an embodiment includes a solar cell module 1 having a plurality of solar cells that generate power, a power conversion unit 2 that, for example, boosts the input voltage from the solar cell module 1 and supplies it to a secondary battery, and a secondary battery 3 that stores the power generated by the solar cell module 1.

[0014] [Solar cell module] Next, a solar cell module 1 according to an embodiment will be described. FIG. 2 is a diagram schematically illustrating an example of a cross section of a main part of a solar cell module according to an embodiment. From FIG. 2 onwards, a part of the solar cell module 1 will be described as a solar cell module 100. In addition, an xyz coordinate system is shown in the following figures. The xy plane direction corresponds to the surface direction of the solar cell 110, transparent layer 140, etc., which will be described later. Hereinafter, unless otherwise specified, "planar view" refers to a view in the z-axis direction (e.g., the negative z-axis direction). "Side view" refers to a view in the x-axis or y-axis direction (e.g., the positive y-axis direction).

[0015] 2, the solar cell module 100 has a plurality of solar cells 110-1 to 110-3, and a wavelength separation lens 120 (optical element) having a fine structure 150 integrated on the solar cells 110-1 to 110-3. The solar cells 110-1 to 110-3 and a solar cell 110-4 described later will be collectively referred to as solar cell 110.

[0016] Each of the solar cell units 110-1 to 110-3 absorbs light in a predetermined wavelength band and converts it into electricity. For example, the solar cell unit 110-1 absorbs light in wavelength band B1 and converts it into electricity. For example, the solar cell unit 110-2 absorbs light in wavelength band B2 and converts it into electricity. For example, the solar cell unit 110-3 absorbs light in wavelength band B3 and converts it into electricity.

[0017] Solar cells 110-1 to 110-3 have p-type semiconductor layers 160-1 to 160-3 and n-type semiconductor layers 170-1 to 170-3, respectively, as photoelectric conversion units. Each solar cell 110-1 to 110-3 has a material with high light absorptance in the corresponding wavelength bands B1, B2, and B3 as its photoelectric conversion unit. An anti-reflection layer 180 is stacked on the n-type semiconductor layers 170-1 to 170-3. Solar cells 110-1 to 110-3 also have a front electrode 190 connected to the n-type semiconductor layers 170-1 to 170-3 and a back electrode 200 connected to the p-type semiconductor layers 160-1 to 160-3.

[0018] The materials constituting the photoelectric conversion section include, for example, silicon-based materials such as x-Si and a-Si:H, GaAs, InAs, GaInAs, Zn3P2, Cu2S, CuInSe2, and CuIn. 1-x These include compound semiconductors such as GaxSe2, InP, CdTe, and CdS, organic semiconductors, photocatalytic materials (such as titanium oxide), and dye-sensitized materials consisting of dye molecules.

[0019] The wavelength separation lens 120 separates incident light (for example, sunlight) into wavelength bands (for example, wavelength bands B1, B2, B3) and focuses the light onto each of the solar cells 110-1 to 110-3. The wavelength separation lens 120 focuses wavelength band B1 of the incident light onto solar cell 110-1. The wavelength separation lens 120 focuses wavelength band B2 of the incident light onto solar cell 110-2. The wavelength separation lens 120 focuses wavelength band B3 of the incident light onto solar cell 110-3. The wavelength bands (B k ) correspond to bands obtained by arbitrarily dividing the spectral wavelength band of sunlight. Alternatively, the wavelength separating lens 120 may be designed so that the wavelength bands separated by the wavelength separating lens 120 match the absorption spectrum of an existing solar cell 110.

[0020] The wavelength separation lens 120 has a transparent layer 140 that covers the plurality of solar cells 110-1 to 110-3, and a plurality of columnar structures 150 that are arranged on the bottom surface of the transparent layer 140. The structures 150 are supported by the transparent layer 140 above.

[0021] The transparent layer 140 is a low-refractive-index transparent layer made of a material such as SiO2 (refractive index n=1.45). In Fig. 2, an example is shown in which the wavelength separation lens 120 is formed on the solar cell 1110 via the transparent layer 130 (for example, an air layer (refractive index n=1.00)), but the solar cell module 100 may be configured such that the transparent layer 140 covers the space between the wavelength separation lens 120 and the solar cell 110.

[0022] The plurality of structures 150 are arranged so as to separate incident light into each predetermined wavelength band and concentrate the light onto the solar cell 110-110-3 corresponding to each wavelength band. The plurality of structures 150 are arranged in the plane direction of the transparent layer 140 at a period equal to or less than the wavelength of the incident light. The plurality of structures 150 are made up of columnar structures of a constant height, and their in-plane shapes (upper and lower surfaces) have four-fold rotational symmetry. In this embodiment, the shape of the structures 150 is four-fold rotational symmetry to suppress the occurrence of polarization dependency.

[0023] Each of the plurality of structures 150 is made of a material such as TiO2 or SiN that has a refractive index higher than that of the transparent layers 130, 140. Each of the plurality of structures 150 is a columnar structure that imparts an optical phase delay amount to incident light according to the cross-sectional shape when the transparent layers 130, 140 are viewed in plan. The cross-sectional shape of the plurality of structures 150 is set according to an optical phase delay distribution for achieving light concentration on each of the solar cell units 110-1 to 110-3, and the structures 150 are arranged according to the optical phase delay distribution for achieving light concentration on each of the solar cell units 110-1 to 110-3.

[0024] In this way, the solar cell module 100 separates incident light into multiple wavelength bands (for example, wavelength bands B1, B2, and B3), and receives the light with solar cell cells 110 (for example, 110-1 to 110-3) having light absorption spectra suited to each wavelength band. Therefore, the solar cell module 100 maximizes the amount of photoelectric conversion in each wavelength band, increasing efficiency compared to conventional solar cell modules.

[0025] Each solar cell 110 (for example, 110-1 to 110-3) may have a photoelectric conversion unit using a single material. Therefore, even if the solar cells 110 are made of materials that would be difficult to join together in conventional tandem solar cells, each solar cell 110 having an optical absorption spectrum corresponding to each of the separated wavelength bands can be used simultaneously. Therefore, the solar cell module 100 can efficiently absorb and photoelectrically convert light in multiple wavelength bands compared to conventional solar cells, and can also be fabricated with significantly less difficulty and at lower costs compared to conventional tandem solar cells.

[0026] There is no limit to the number of wavelength bands separated by the wavelength separation lens 120, as long as there is more than one. The wavelength separation lens 120 may also focus light of the same wavelength band onto multiple solar cells 110. For example, the wavelength separation lens 120 focuses light of wavelength band B1 onto solar cell 110-1, but when solar cell 110-3 is placed in the position of solar cell 110-1, the wavelength separation lens 120 may be designed to focus light of wavelength band B3 onto this solar cell 110-3 instead of wavelength band B1. The wavelength separation lens 120 and solar cell 110 may be arranged in an array, or may be composed of one wavelength separation lens 120 and multiple solar cell 110 as shown in FIG. 2.

[0027] [First configuration example] Next, a solar cell module 100-1 having a first configuration example will be described. Fig. 3 is a diagram schematically showing the arrangement of solar cells 110 when the solar cell module 100-1 according to the embodiment is viewed from above. Fig. 4 is a diagram showing an example of a cross section of the solar cell module 100-1 when viewed from the side along line aa' in Fig. 3. Fig. 5 is a diagram showing an example of a cross section of the solar cell module 100-1 when viewed from the side along line bb' in Fig. 3. In Figs. 4 and 5, arrows schematically indicate light incident on the solar cell module 100-1.

[0028] In the solar cell module 100-1, four solar cells having optical absorption spectra corresponding to wavelength bands B1, B2, B3, and B4, respectively, are arranged adjacent to each other as shown in Fig. 3 to form one unit (unit pattern) U1-1. Then, as shown in Figs. 4 and 5, a wavelength separation lens 120-1 is arranged above the solar cells 110-1 to 110-4. Alternatively, for example, one wavelength separation lens 120-1 may face the four solar cells 110-1 to 110-4 directly below it.

[0029] The solar cell 110-4 absorbs light in wavelength band B4 and converts it into electricity. The solar cell 110-4 has a p-type semiconductor layer 160-4 and an n-type semiconductor layer 170-4 as a photoelectric conversion unit, an anti-reflection layer 180 stacked on the n-type semiconductor layer 170-4, a front electrode 190 connected to the n-type semiconductor layer 170-4, and a back electrode 200 connected to the p-type semiconductor layer 160-4.

[0030] The wavelength separation lens 120-1 separates the incident light into wavelength bands B1, B2, B3, and B4, and collects the separated light onto the solar cells 110-1 to 110-4 having light absorption spectra suited to the respective wavelength bands B1, B2, B3, and B4.

[0031] The wavelength separation lens 120-1 focuses light in wavelength band B1 out of the incident light onto the solar cell 110-1. The wavelength separation lens 120-1 focuses light in wavelength band B2 out of the incident light onto the solar cell 110-2. The wavelength separation lens 120-1 focuses light in wavelength band B3 out of the incident light onto the solar cell 110-3. The wavelength separation lens 120-1 focuses light in wavelength band B4 out of the incident light onto the solar cell 110-4. The power generated by the solar cell cells 110-1 to 110-4 is output to the power conversion unit 2 via wiring connected to the back electrode 200 and the front electrode 190.

[0032] The wavelength separating lens 120-1 is provided so as to cover the solar cells 110-1 to 110-4. An example of the wavelength separating lens 120-1 is a metasurface. The metasurface is configured to include a plurality of microstructures (corresponding to the structures 150) having a width equal to or less than the wavelength of light. The metasurface may have a two-dimensional structure or a three-dimensional structure. The wavelength separating lens 120-1 can control the phase and light intensity according to the characteristics of light (wavelength, polarization, and angle of incidence) simply by changing the parameters of the structures 150. Furthermore, a three-dimensional structure offers greater design freedom than a two-dimensional structure.

[0033] The wavelength separation lens 120-1 has two functions: a wavelength separation function and a lens function. The wavelength separation function is to separate incident light into light of each wavelength band. The lens function is to focus light of each wavelength onto the corresponding pixel.

[0034] In this example, the wavelength separation function of wavelength separation lens 120-1 separates incident light into wavelength bands B1, B2, B3, and B4. The lens function of wavelength separation lens 120-1 condenses the light in wavelength bands B1, B2, B3, and B4 onto solar cells 110-1 to 110-4 corresponding to wavelength bands B1, B2, B3, and B4, respectively.

[0035] 6 to 9 are diagrams schematically showing the concentration of light onto solar cells 110-1 to 110-4 in solar cell module 100-1 shown in FIG.

[0036] In the solar cell module 100-1, as shown by the arrows in Fig. 6, the wavelength separation function and lens function of the wavelength separation lens 120-1 cause light in wavelength band B1 to be concentrated on the solar cell 110-1 corresponding to wavelength band B1. In this example, not only light from above (positive direction of the z-axis) the solar cell 110-1 but also light around the solar cell 110-1 is concentrated on the solar cell 110-1. In other words, the multiple structures 150 are arranged so that light in wavelength band B1 that is incident outside the region facing the solar cell 110-1 is also concentrated on the solar cell 110-1.

[0037] In the solar cell module 100-1, the wavelength separation function and lens function of the wavelength separation lens 120-1 cause light in wavelength band B2 to be concentrated on the solar cell 110-2 corresponding to wavelength band B2, as shown by the arrows in Fig. 7. The multiple structures 150 are arranged so that light in wavelength band B2 that is incident outside the region facing the solar cell 110-2 is also concentrated on the solar cell 110-2.

[0038] In the solar cell module 100-1, the wavelength separation function and lens function of the wavelength separation lens 120-1 cause light in wavelength band B3 to be concentrated on the solar cell 110-3 corresponding to wavelength band B3, as shown by the arrows in Fig. 8. The multiple structures 150 are arranged so that light in wavelength band B3 that is incident outside the region facing the solar cell 110-3 is also concentrated on the solar cell 110-3.

[0039] In the solar cell module 100-1, the wavelength separation function and lens function of the wavelength separation lens 120-1 cause light in wavelength band B4 to be concentrated on the solar cell 110-4 corresponding to wavelength band B4, as shown by the arrows in Fig. 9. The multiple structures 150 are arranged so that light in wavelength band B4 that is incident outside the region facing the solar cell 110-4 is also concentrated on the solar cell 110-4.

[0040] By arranging multiple structures 150 in this manner, the solar cell module 100-1 can receive a greater amount of light than when only light in the wavelength bands B1, B2, B3, and B4 of the incident light in the opposing areas of the solar cells 110-1 to 110-4 is concentrated onto the solar cells 110-1 to 110-4.

[0041] The wavelength separation lens 120-1 may focus light of the same wavelength band on multiple solar cells 110. The wavelength separation lens 120-1 focuses light of wavelength band B2 on solar cell 110-2, but when solar cell 110-4 is placed at the position of solar cell 110-2, the lens may be designed to focus light of wavelength band B4 on this solar cell 110-4 instead of wavelength band B2.

[0042] [Second configuration example] Next, a solar cell module 100-2 having a second configuration example will be described. Fig. 10 is a diagram schematically showing the arrangement of solar cells 110 when the solar cell module 100-2 according to the embodiment is viewed from above. Fig. 11 is a diagram showing an example of a cross section of the solar cell module 100-2 when viewed from the side along line cc' in Fig. 10. In Fig. 11, arrows schematically show light incident on the solar cell module 100-2.

[0043] In the solar cell module 100-2, three solar cells having light absorption spectra corresponding to wavelength bands B1, B2, and B3, respectively, are arranged in parallel to form one unit U1-2 as shown in Fig. 10. Then, as shown in Fig. 11, a wavelength separation lens 120-2 is arranged above the solar cells 110-1 to 110-3. For example, one wavelength separation lens 120-2 may face the three solar cells 110-1 to 110-3 directly below it.

[0044] The wavelength separation lens 120-2 separates the incident light into wavelength bands B1, B2, and B3, and focuses the separated light onto the solar cells 110-1 to 110-3 having light absorption spectra suited to the respective wavelength bands B1, B2, and B3.

[0045] The wavelength separation lens 120-2 focuses light in wavelength band B1 out of the incident light onto the solar cell 110-1. The wavelength separation lens 120-2 focuses light in wavelength band B2 out of the incident light onto the solar cell 110-2. The wavelength separation lens 120-2 focuses light in wavelength band B3 out of the incident light onto the solar cell 110-3. The power generated by the solar cells 110-1 to 110-3 is output to the power conversion unit 2 via wiring connected to the back electrode 200 and the front electrode 190.

[0046] The wavelength separation lens 120-2 is provided so as to cover the solar cells 110-1 to 110-3. An example of the wavelength separation lens 120-2 is a metasurface.

[0047] The wavelength separation lens 120-2 has two functions: a wavelength separation function and a lens function. In this example, the wavelength separation function of the wavelength separation lens 120-2 separates incident light into wavelength bands B1, B2, and B3. The lens function of the wavelength separation lens 120-2 condenses the light in the wavelength bands B1, B2, and B3 onto the solar cells 110-1 to 110-3 corresponding to the wavelength bands B1, B2, and B3, respectively.

[0048] 12 to 14 are diagrams schematically showing the concentration of light onto solar cells 110-1 to 110-3 in solar cell module 100-2 shown in FIG.

[0049] In the solar cell module 100-2, light in wavelength band B1 is concentrated on the solar cell 110-1 corresponding to wavelength band B1, as shown by the arrows in Fig. 12. In this example, not only light from above (positive direction of the z-axis) the solar cell 110-1 but also light around the solar cell 110-1 is concentrated on the solar cell 110-1. The multiple structures 150 are arranged so that light in wavelength band B1 that is incident outside the region facing the solar cell 110-1 is also concentrated on the solar cell 110-1.

[0050] In the solar cell module 100-2, light in wavelength band B2 is concentrated on the solar cell 110-2 corresponding to wavelength band B2, as shown by the arrows in Fig. 13. The multiple structures 150 are arranged so that light in wavelength band B2 that is incident outside the region facing the solar cell 110-2 is also concentrated on the solar cell 110-2.

[0051] In the solar cell module 100-2, light in wavelength band B3 is concentrated on the solar cell 110-3 corresponding to wavelength band B3, as shown by the arrows in Fig. 14. The multiple structures 150 are arranged so that light in wavelength band B3 that is incident outside the region facing the solar cell 110-3 is also concentrated on the solar cell 110-3.

[0052] By arranging multiple structures 150 in this manner, the solar cell module 100-2 can receive a greater amount of light than when only light in wavelength bands B1, B2, and B3 of incident light in the opposing areas of the solar cells 110-1 to 110-3 is concentrated onto the solar cells 110-1 to 110-3.

[0053] The wavelength separation lens 120-2 may focus light of the same wavelength band on multiple solar cells 110. The wavelength separation lens 120-2 focuses light of wavelength band B1 on solar cell 110-1, but when solar cell 110-3 is placed at the position of solar cell 110-1, the lens may be designed to focus light of wavelength band B3 on solar cell 110-3 instead of wavelength band B1.

[0054] [Example of wavelength separation lens structure] 2, the wavelength separation lens 120 is formed on the bottom surface of the transparent layer 140, but this is not limiting. Figures 15 to 24 are diagrams schematically showing other examples of a part of the cross section of the wavelength separation lens 120 according to the embodiment.

[0055] 15, the structure 150 may be formed on the upper surface of the transparent layer 140. In this case, the structure 150 is supported on the upper surface of the transparent layer 140. The transparent layer above the structure 150 may be air or a protective layer such as a resin, and the transparent layer 140 may be made of a single material or may be made of multiple layers of materials.

[0056] As shown in wavelength separation lens 120B in Fig. 16 and wavelength separation lens 120C in Fig. 17, the structure 150 may be formed of multiple layers along the stacking direction of the transparent layer 140. When the structure 150 is configured of multiple layers, the design parameters can be increased by the amount of the increase in layers compared to when the structure 150 is a single layer, which increases the light control ability and enables more efficient wavelength band separation.

[0057] In the wavelength separation lens 120B, one layer of structures 150-1 and 150-2 is formed on the upper surface of the transparent layer 140 and one layer of structures 150-2 is formed inside the transparent layer 140. In the wavelength separation lens 120C, a total of three layers of structures 150-1 to 150-3 are formed: one layer on the upper surface of the transparent layer 140 and two layers inside the transparent layer 140. The structure 150-1 is supported on the upper surface of the lower transparent layer 140. The material of the structures 150-1 to 150-3 may be the same within a layer or may be the same for all layers. Furthermore, the material of the structures 150-1 to 150-3 may be different for each location and / or for each layer. The height, cross-sectional shape, and dimensions of the structures 150-1 to 150-3 may be the same within a layer and / or for all layers, or may be different for each location and / or for each layer.

[0058] 18, wavelength separating lens 120E in FIG. 19, and wavelength separating lens 120G in FIG. 20, the structures 150 may be formed inside the transparent layer 140. In the wavelength separating lens 120D, a single layer of structures 150 is formed inside the transparent layer 140. In the wavelength separating lens 120E, two layers of structures 150-1 and 150-2 are formed inside the transparent layer 140. In the wavelength separating lens 120G, three layers of structures 150-1 to 150-3 are formed inside the transparent layer 140.

[0059] 21 and 22, the structures 150 may be formed on the bottom surface of the transparent layer 140 and inside the transparent layer 140. In the wavelength separating lens 120H, structures 150-1 and 150-2 are formed on the bottom surface of the transparent layer 140 and inside the transparent layer 140, respectively. In the wavelength separating lens 120I, structures 150-1 to 150-3 are formed in a total of three layers: one layer on the bottom surface of the transparent layer 140 and two layers inside the transparent layer 140. The structures 150-2 of the wavelength separating lens 120H and 150-3 of the wavelength separating lens 120I are supported by the transparent layer 140 above.

[0060] 23 and 24, the structures 150 may be formed on the top and bottom surfaces of the transparent layer 140. In the wavelength separating lens 120J, structures 150-1 and 150-2 are formed on the top and bottom surfaces of the transparent layer 140, respectively. In the wavelength separating lens 120K, structures 150-1 to 150-3 are formed on the top surface of the transparent layer 140, the bottom surface of the transparent layer 140, and inside the transparent layer 140, respectively. The structures 150-1 of the wavelength separating lens 120J and the wavelength separating lens 120K are supported by the transparent layer 140 below. The structures 150-2 of the wavelength separating lens 120J and the structure 150-3 of the wavelength separating lens 120K are supported by the transparent layer 140 above.

[0061] The region between the wavelength separation lens 120 and the solar cell 110 may be filled with an air layer, or they may be connected via a transparent layer.

[0062] [Method of realizing wavelength separation lens] Next, a method for realizing the wavelength separation lens 120-2 in the second configuration example, in which the structure 150 has two layers, will be described.

[0063] To realize the wavelength separation lens 120-2 having different focusing positions depending on the wavelength band of the incident light, it is necessary to realize a structure that gives different optical wavefronts for each wavelength band.

[0064] Therefore, the wavelength separation lens 120 is realized by utilizing the wavelength dispersion characteristics of the amount of optical phase delay that the fine columnar structures (structures 150) give to incident light.

[0065] The structure 150 of each layer is formed from a material such as TiO2 or SiN having a refractive index n1 higher than the refractive index n0 of the transparent layers 130 and 140 surrounding the structure 150. From the viewpoint of ease of fabrication, the structure 150 is formed from a material such as TiO2 or SiN having a height (length in the z-axis direction) h layer A structure having a constant thickness in the plane is preferable. Note that the structures 150 may have different heights for each layer.

[0066] The bottom and top surfaces of the structure 150 have a four-fold rotational symmetry shape. This shape suppresses the occurrence of polarization dependence.

[0067] The structure 150 can be considered as an optical waveguide that confines and propagates light due to the refractive index difference from the transparent layers 130 and 140. Therefore, when light is incident from the upper surface side of the structure 150, the light propagates while being strongly confined within the structure 150, and undergoes a phase delay effect determined by the effective refractive index n eff of the optical waveguide, and is output from the bottom surface side of the structure 150.

[0068] Specifically, when the phase of the light propagating through the length of the thickness of the transparent layer 140 is used as a reference, the optical phase delay amount φ layer by each layer of the structure 150 is expressed by Equation (1), where λ is the wavelength of the light in vacuum.

[0069]

Equation

[0070] This optical phase delay amount φ layer varies depending on the wavelength λ of the light. Therefore, in the same structure 150, different optical phase delay amounts φ layer can be given according to the wavelength band of the light.

[0071] Furthermore, the effective refractive index n eff of the optical waveguide is known to strongly depend on the cross-sectional shape of the structure 150, and takes values of n0 < n eff < n1.

[0072] Also, the effective refractive index n eff of the optical waveguide varies depending on the wavelength λ of the light, and the degree of variation strongly depends on the cross-sectional shape of the structure 150.

[0073] Therefore, by using the columnar structure 150 with various cross-sectional shapes, the phase delay amount φ layerIt is possible to set a wide variety of combinations.

[0074] By appropriately arranging these multiple structures 150 in the surface direction of the transparent layer 140, it becomes possible to form a spatial phase distribution (optical phase delay amount distribution) that differs for each wavelength, and by making the spatial phase distribution a distribution that corresponds to the lens, it becomes possible to newly design and realize a wavelength separation lens 120 that has different focusing positions depending on the wavelength band.

[0075] The arrangement period P of the structures 150 is set to λ 1 / λ 2 , which is the shortest center wavelength of the desired light receiving wavelength band, in order to prevent the light diffraction phenomenon that causes a decrease in efficiency. min Then, it is desirable to set it as shown in formula (2): where n0 is the refractive index of the transparent layer 140 located on the transmission side.

[0076]

number

[0077] Next, we will explain the advantages of multi-layering the structure 150. In the case of a single-layer structure 150, the height h1 of the single-layer structure 150 is equal to the optical phase delay amount φ layer Since it is preferable that the wavelength of the light having a center wavelength of 2π or more is λ , the desired center wavelength in the wavelength range on the longest wavelength side of the wavelength range to be separated is λ . r In this case, it is desirable to set it as in equation (3).

[0078]

number

[0079] In the visible light region, when n1 is the refractive index of SiN of the structure 150 and n0 is the refractive index of SiO2 of the transparent layers 130 and 140, the height h1 of the single-layer structure 150 is preferably 1060 nm or more.

[0080] In this case, if the arrangement period P of each structure 150 is set to be equal to or less than the shortest wavelength in the transparent material, for example, 280 nm or less when λ is 410 nm and n0 is the refractive index of SiO2, the aspect ratio of the structure 150 needs to be 3.8 or more.

[0081] The cross-sectional dimension of the actual structure 150 is made smaller than the structural period P in order to reduce optical coupling between adjacent structures 150. If the maximum dimension is 200 nm, the aspect ratio will be 5.3 or more. Furthermore, the effective refractive index n eff Some structures 150 have been used with smaller cross-sectional dimensions for control purposes, with a minimum of 80 nm resulting in an aspect ratio of approximately 13.3.

[0082] To fabricate such a fine structure with a high aspect ratio using a conventional semiconductor process, generally, advanced fabrication techniques are required.

[0083] In contrast, by dividing the structure 150 into multiple layers in the height direction, the required optical phase delay amount φ layer While ensuring this, the aspect ratio of the fine structure 150 can be reduced.

[0084] For example, in the visible light region, when two layers of the structure 150 are formed, n1 is the refractive index of SiN of the structure 150, n0 is the refractive index of SiO2 of the transparent layer 140, and the height h of the structure 150 of each layer is 1,2 The thickness can be about half that of a single layer, for example, 530 nm or less. Therefore, the aspect ratio can be reduced to about half. Similarly, when a three-layer structure 150 is formed, the aspect ratio can be reduced to one-third.

[0085] Furthermore, the cross-sectional dimensions of each structure 150 divided by layering do not need to be the same as before division, and may be different for each layer.

[0086] At this time, as is clear from the above formula, by forming the structure 150 into multiple layers, neff The wavelength dispersion and the optical phase delay amount φ corresponding to the wavelength λ of light can be arbitrarily changed by changing the cross-sectional dimensions. layer This makes it possible to set a wider variety of combinations, thereby improving wavelength separation efficiency and light collection efficiency.

[0087] [Structure] The following describes the shape of the structure 150 in the wavelength separation lens 120 in the second configuration example when the structure 150 has two layers. Note that other configuration examples can also be configured using similar design guidelines.

[0088] Figures 25 to 30 are diagrams showing an example of the schematic configuration of the structure 150 shown in Figure 2. Figure 25 is a side view of the structure 150 which has a square shape when viewed from above. Figure 26 is a bottom view of the structure 150 shown in Figure 25. In this example, a case where incident light is in the visible light region will be described.

[0089] The structure 160 is a columnar structure extending in the z-axis direction, and is formed in the transparent layer 140 (for example, SiO2 (refractive index n eff The structure 150 is formed on the bottom surface of a silicon nitride (refractive index n1=1.45). The material of the structure 150 is SiN (refractive index n1=2.05). The sides and bottom of the structure 150 are air (refractive index n0=1.0).

[0090] The arrangement period of the structures 160 is defined as P. The arrangement period P is preferably set as shown in formula (2) so that diffracted light does not occur on the transmission side. Here, the shortest wavelength λ of the received wavelength band is min is set to 410 nm, n0 is set to 1.45, and the arrangement period P is set to 280 nm.

[0091] Height h of structure 150 layer The height h (length in the z-axis direction) is constant. layerIn this case, it is preferable that the structure 150 has an optical phase delay (phase value) of 2π or more with respect to the incident light, i.e., the light traveling along the z-axis direction. Let the number of layers be L, and let λ be the desired center wavelength in the wavelength range on the longest wavelength side of the wavelength range to be separated. r Then, the height h layer It is desirable to set it as shown in equation (4).

[0092]

number

[0093] Here, L=2, and from equation (4), the height of each floor h 1,2 = 850 nm.

[0094] By designing the cross-sectional shape of the structure 160 and its dimensional parameters (width of the structure), various combinations of different phase values ​​can be realized at multiple wavelengths.

[0095] In this case, as is clear from equation (1), by changing the cross-sectional shape and dimension parameters for each layer, the effective refractive index n eff The value of and chromatic dispersion can be varied.

[0096] In addition, when the structure 150 has a plurality of layers, the optical phase delay amount φ layer Considering this, a wider variety of combinations of phase values ​​becomes possible, leading to an increase in the degree of freedom in designing lens functions that differ for each wavelength range.

[0097] The cross-sectional shape of the structure 150 is preferably a four-fold rotationally symmetric shape so as to avoid polarization dependency. Fig. 27 is a side view of the structure 150 which has an X-shape when viewed in a plane. Fig. 28 is a plan view of the structure 150 shown in Fig. 27. Fig. 29 is a side view of the structure 150 which has a hollow diamond shape when viewed in a plane. Fig. 30 is a plan view of the structure 150 shown in Fig. 29. The cross-sectional shape of the structure 150 may be an X-shape or a hollow diamond shape, which is obtained by rotating a columnar structure having a cross shape and a square with a square hole by 45° in-plane, as shown in Figs. 27 to 30.

[0098] 27 to 30, a columnar structure having a square with a cross-shaped and square hole rotated by 45° in-plane is used as the cross-sectional shape of the structures 150, which has the effect of weakening the optical coupling with adjacent structures 150 compared to a structure that is not rotated. Even when various structures 150 are arranged periodically, the optical properties of each structure 150 are not affected by the adjacent structures 150, and this has the effect of making it easy to reproduce the designed spatial phase distribution.

[0099] When the structure 150 has multiple layers, the distance between each layer can be set arbitrarily, but considering multiple reflections between layers and the dissipation and radiation of light after passing through the layers, it is desirable to set the distance to approximately the wavelength or less. Furthermore, the structures 150 in each layer may be connected. In other words, the distance between layers may be zero.

[0100] The cross-sectional shape of the structure 150 is not limited to the shapes shown in Fig. 26, Fig. 28, and Fig. 30. Fig. 31 is a diagram showing examples of the cross-sectional shape of the structure 150 shown in Fig. 2. The wavelength separation lens 120 may employ structures 160 having various cross-sectional shapes as exemplified in Fig. 31. The exemplified shapes are, for example, four-fold rotationally symmetric shapes obtained by combining and rotating various square, cross, and circular shapes.

[0101] [Wavelength separation lens design example 1] Next, a design example of a wavelength separation lens will be described. In this example, for example, a wavelength separation lens 120-1 of a solar cell module 100-1 of a first configuration example shown in Figs. 3 to 6 is assumed. The number of wavelength band divisions of the wavelength separation lens 120-1 is four. Note that a similar design to the following can also be applied to other numbers of wavelength divisions.

[0102] In lens design, the cross-sectional shape and arrangement of the structures 150 are designed to achieve an ideal optical phase delay distribution (phase distribution). In the example described below, a lens phase distribution with a different focal point for each wavelength band is designed and realized with a single-layer or multi-layer columnar structure 150. In this example, a structure 150 made of SiN is used, and by utilizing the wavelength dispersion characteristics of the optical phase delay, a different phase distribution is designed for each center wavelength of each wavelength band from 400 nm to 1200 nm, thereby realizing a wavelength separation lens 120-1.

[0103] The figures show ideal optical phase delay distributions for unit U1-1 (solar cell 110-1 to 110-4). Fig. 32 shows an ideal optical phase delay distribution when the central wavelength is 500 nm. Fig. 33 shows an ideal optical phase delay distribution when the central wavelength is 650 nm. Fig. 34 shows an ideal optical phase delay distribution when the central wavelength is 800 nm. Fig. 35 shows an ideal optical phase delay distribution when the central wavelength is 1000 nm. In Figs. 32 to 35, the central positions of the four solar cell 110-1 to 110-4 (unit U1-1) correspond to x=0, y=0.

[0104] The parameters of the design example are as follows: Solar cell size: 15mm x 15mm Focal length: 15mm Center wavelength of each wavelength band: Wavelength band B1: 500 nm, Wavelength band B2: 650 nm, Wavelength band B3: 800 nm, Wavelength band B4: 1000 nm

[0105] If the ideal optical phase delay distribution is φ, then φ is expressed by the following equation (5).

[0106]

number

[0107] In the above equation (5), λ d is the center wavelength (design wavelength). x f , y f and z f is the focusing position. n2 is the refractive index of the lower transparent layers 130, 140. C is an arbitrary constant.

[0108] 32 to 35, a phase distribution was set to provide the following light collection positions for wavelength bands B1, B2, B3, and B4, respectively, in accordance with the positions of four solar cell units 110-1 to 110-4. The center positions of the four solar cell units 110-1 to 110-4 (unit U1-1) correspond to x=0, y=0. Wavelength band B1:x f =+7.5mm, y f =-7.5mm, z f =15mm Wavelength band B2:x f =+7.5mm, y f =+7.5mm, z f =15mm Wavelength band B3:x f =-7.5mm, y f =-7.5mm, z f =15mm Wavelength band B4:x f =-7.5mm, y f =+7.5mm, z f =15mm

[0109] φ is converted to fall within the range of 0 to 2π. For example, -0.5π and 2.5π are converted to 1.5π and 0.5π, respectively. The boundary region of the phase distribution is set so that the phase distribution of the lens at each center wavelength is symmetrical (to the left and right, up and down) around the focusing position (together with adjacent lenses). The constant C may be optimized for each wavelength to minimize the error in the phase distribution.

[0110] Then, based on the amount of optical phase delay at each wavelength possessed by the composition structure, the structure that best matches the phase distribution of the above four wavelengths, i.e., the structure 150 that has the smallest phase error, can be selected and placed for each position. In this case, the structural pattern on each cell has two-fold rotational symmetry due to the number of wavelength band divisions and the symmetry of the phase distribution.

[0111] [Wavelength separation lens design example 2] Next, another design example of the wavelength separation lens will be described. In this example, for example, a wavelength separation lens 120-2 of the solar cell module 100-2 of the second configuration example shown in Fig. 10 and Fig. 11 is assumed. The number of wavelength band divisions of the wavelength separation lens 120-2 is 3. Note that the same design as below can be applied to other numbers of wavelength divisions.

[0112] In lens design, the cross-sectional shape and arrangement of the structures 150 are designed to achieve an ideal optical phase delay distribution (phase distribution). In the example described below, a lens phase distribution with a different focal point for each wavelength band is designed and realized with a single-layer or multi-layer columnar structure 150. In this example, a structure 150 made of SiN is used, and by utilizing the wavelength dispersion characteristics of the optical phase delay, a different phase distribution is designed for each center wavelength of each wavelength band from 400 nm to 1200 nm, thereby realizing a wavelength separation lens 120-2.

[0113] Fig. 36 shows an ideal optical phase delay distribution for unit U1-2 (solar cell 110-1 to 110-3). Fig. 36 is a diagram showing an ideal optical phase delay distribution when the central wavelength is 500 nm. Fig. 37 is a diagram showing an ideal optical phase delay distribution when the central wavelength is 650 nm. Fig. 38 is a diagram showing an ideal optical phase delay distribution when the central wavelength is 1000 nm. In Figs. 36 to 38, the central positions of the three solar cell 110-1 to 110-3 (unit U1-2) correspond to x=0, y=0.

[0114] The parameters of the design example are as follows: Solar cell size: 15mm x 15mm Focal length: 30mm Center wavelength of each wavelength band: Wavelength band B1: 500 nm, Wavelength band B2: 650 nm, Wavelength band B3: 1000 nm

[0115] If the ideal optical phase delay distribution is φ, φ is expressed by the following equation (6).

[0116]

number

[0117] In the above equation (6), λ d is the center wavelength (design wavelength). x f , y f and z f is the focusing position. n2 is the refractive index of the lower transparent layers 130, 140. C is an arbitrary constant.

[0118] 36 to 38, a phase distribution was set that provides the following light collection positions for wavelength bands B1, B2, and B3, respectively, in accordance with the positions of the three solar cell units 110-1 to 110-3. The center position of the four solar cell units 110-1 to 110-3 (unit U1-2) corresponds to x=0, y=0. Wavelength band B1:x f =-15mm, y f =0mm, z f =30mm Wavelength band B2:x f =0mm, y f =0mm, z f =30mm Wavelength band B3:x f =+15mm, y f =0mm, z f =30mm

[0119] φ is converted to fall within the range of 0 to 2π. For example, -0.5π and 2.5π are converted to 1.5π and 0.5π, respectively. The boundary region of the phase distribution is set so that the lens phase distribution at each center wavelength is symmetrical (to the left and right, up and down) around the focusing position (together with adjacent lenses). The constant C may be optimized for each wavelength to minimize the phase distribution error.

[0120] Then, based on the phase delay amount at each wavelength of the composition structure, the structure that best matches the phase distribution of the above three wavelengths, i.e., the structure 150 that has the smallest phase error, can be selected and placed for each position. In this case, the structural pattern on each cell will be vertically symmetrical due to the number of wavelength band divisions and the symmetry of the phase distribution.

[0121] [Effects of the embodiment] A conventional solar cell will be described. Fig. 39 is a diagram schematically showing an example of a cross section of a main part of a conventional solar cell module. Fig. 39 shows a solar cell module having a photoelectric conversion unit using only a single material (e.g., Si). Fig. 40 is a diagram schematically showing the wavelength dependency of the light intensity radiated / absorbed by the solar cell module shown in Fig. 39. Curve C1 in Fig. 40 shows the spectrum of sunlight.

[0122] As shown in Figure 40, in a solar cell module having a photoelectric conversion section using only a single material, the efficiency of the module is limited because only a portion of the wavelengths of incident sunlight are photoelectrically converted due to the light absorption spectrum derived from the band gap of the material (see region R11).

[0123] Fig. 41 is a diagram schematically showing another example of a cross section of a main part of a conventional solar cell module. Fig. 41 shows a tandem solar cell module having a photoelectric conversion section using a multi-junction compound semiconductor in which multiple materials with different bandgaps are stacked. Fig. 42 is a diagram schematically showing the wavelength dependence of the light intensity emitted / absorbed by the solar cell module shown in Fig. 41. Curve C1 in Fig. 42 shows the spectrum of sunlight.

[0124] As shown in Figure 42, a tandem solar cell module can absorb and photoelectrically convert light of almost all wavelengths of incident sunlight (see regions R21 to R23), but the absorption rate of light in the long wavelength band, as in region R23, is low, and there is a limit to the improvement of photoelectric conversion efficiency. Furthermore, in tandem solar cells, there are only a limited number of materials that can be joined as multi-junction compound semiconductors, and they are also difficult to fabricate.

[0125] FIG. 43 is a diagram schematically illustrating the wavelength dependence of the light intensity emitted / absorbed by the solar cell module 100 shown in FIG. 2. As shown in FIG. 43, the solar cell module 100 according to the embodiment can absorb and photoelectrically convert light of almost all wavelengths of incident sunlight (see regions R1 to R3). Furthermore, the solar cell module 100 is expected to have improved photoelectric conversion efficiency compared to a tandem solar cell module because it has fewer material restrictions. For example, the solar cell module 100 may be able to select a material for the photoelectric conversion section that has better absorption characteristics at long wavelengths, even though this is difficult to use in a tandem solar cell module. In this case, as shown in region R23, it is believed that the solar cell module 100 will have a higher absorptivity for light in the long wavelength band than a tandem solar cell module, and thus achieve a higher photoelectric conversion efficiency.

[0126] This is because wavelength separation lens 120 separates all incident light into wavelength bands and focuses the light onto each solar cell 110-1 to 110-3 corresponding to each wavelength band, thereby increasing absorption efficiency over a wide range of the sunlight spectrum. Therefore, solar cell module 100 can increase the total photoelectric conversion amount compared to solar cell modules and tandem solar cell modules having conventional photoelectric conversion units made of a single material.

[0127] Furthermore, in the solar cell module 100, each solar cell 110 may have a photoelectric conversion section using a single material suited to each wavelength band. Therefore, the solar cell module 100 makes it possible to simultaneously use solar cell cells 110 each made of materials that would be difficult to join together in a tandem solar cell, and is expected to maximize photoelectric conversion efficiency by using a material that can more efficiently absorb and convert sunlight into electricity in the photoelectric conversion section.

[0128] Furthermore, in the solar cell module 100, each solar cell 110 can be a photoelectric conversion unit using a single material that is suited to each wavelength band, which significantly reduces the difficulty of fabrication compared to tandem solar cells, leading to reduced fabrication costs.

[0129] Furthermore, in the solar cell module 100, when the structure 150 of the wavelength separation lens 120 has a multi-layer structure, the design parameters can be increased by the amount of the increase in layers compared to when the structure 150 has a single-layer structure, thereby increasing the light control ability and enabling more efficient wavelength band separation.

[0130] There is no limit to the number of wavelength bands that can be separated in the solar cell module 100, and any number of wavelength bands will provide the desired effect. Furthermore, the solar cell module 100 allows light of the same wavelength band to be concentrated onto multiple solar cells 110, allowing for a high degree of freedom in design.

[0131] 1 and the like is also one aspect of the present disclosure. The conversion device 10 according to the embodiment includes the solar cell module 100 described above, and therefore, compared to conventional conversion devices, the photoelectric conversion efficiency can be improved and the manufacturing cost can be reduced. [Explanation of symbols]

[0132] 1,100,100-1,100-2 Solar Cell Module 2 Power conversion section 3 Secondary battery 10. Conversion Device 110, 110-1 to 110-4 solar cell 120, 120-1, 120-2 wavelength separation lens 130,140 transparent layer 150,150-1~150-3 structure 160-1~160-4 p-type semiconductor layer 170-1 to 170-4 n-type semiconductor layer 180 Anti-reflection layer 190 Surface electrode 200 Back electrode

Claims

1. a plurality of solar cells, each of which absorbs light in a predetermined wavelength band set for it and converts it into electricity; an optical element including: a transparent layer covering the plurality of solar cells; and a plurality of structures arranged on or within the transparent layer in a plane direction of the transparent layer at a period equal to or less than the wavelength of incident light, the plurality of structures being arranged so as to separate the incident light into predetermined wavelength bands and collect the light onto the solar cells corresponding to each wavelength band; and The solar cell module is characterized in that the plurality of structures are formed in a plurality of layers on or within the transparent layer along a stacking direction of the transparent layer.

2. each of the plurality of structures is a columnar structure having a refractive index higher than a refractive index of the transparent layer and imparting an optical phase delay amount to incident light according to a cross-sectional shape of the transparent layer when viewed in a plane; 2. The solar cell module according to claim 1, wherein the plurality of structures have cross-sectional shapes set in accordance with an optical phase delay distribution for achieving the light concentration, and are arranged in accordance with the optical phase delay distribution for achieving the light concentration.

3. 2. The solar cell module according to claim 1, wherein the cross-sectional shape of each of the plurality of structures is a four-fold rotationally symmetric shape.

4. The solar cell module according to any one of claims 1 to 3, a secondary battery that stores power; a power conversion unit that boosts an input voltage from the solar cell module and supplies the boosted voltage to the secondary battery; A conversion device comprising:

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