WO2024157371A1 - Solar battery module and conversion device - Google Patents

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

Solar cell modules and conversion devices

The present invention relates to a solar cell module and a conversion device.

　In order to realize a carbon-neutral society, research and development into solar cells is progressing. Conventionally, technology has been provided for modularizing and arraying solar cells with a photoelectric conversion section that uses a single material (e.g., Si) for the photoelectric conversion of sunlight. In such general solar cells that use only Si, only a portion of the wavelengths of incident light are converted into electricity due to the optical absorption spectrum resulting from the band gap of the material. Therefore, in solar cells that use only Si, the optical absorption spectrum resulting from the band gap of the material means that all of the sunlight, which has a wide spectrum, cannot be efficiently absorbed and photoelectrically converted, limiting the efficiency of the module.

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, and that efficiently absorbs and photoelectrically converts sunlight with a wide spectrum (Non-Patent Document 1).

J. F. Geisz, R. M. France, K. L. 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, 2020], Internet <URL: https://doi.org/10.1038/s41560-020-0598-5>

However, there is a problem with tandem solar cells in that there is a limit to the materials that can be bonded as multi-junction compound semiconductors, and there is a limit to how much improvement can be made in photoelectric conversion efficiency.

The present invention has been made in consideration of the above, and aims to provide a solar cell module and conversion device that can improve photoelectric conversion efficiency.

In order to solve the above 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 respective predetermined wavelength band 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 smaller than the wavelength of the incident light, the plurality of structures being arranged to separate the incident light into each of the predetermined wavelength bands and focus the light on the solar cell corresponding to each wavelength band.

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.

The present invention provides a solar cell module and conversion device that can improve photoelectric conversion efficiency.

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

Below, the best mode for carrying out the present invention will be explained in detail with reference to the drawings. Note that in the following explanation, each figure 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 only the shape, size, and positional relationship exemplified in each figure. In addition, in the description of the drawings, the same parts are denoted by the same reference numerals.

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

For example, as shown in FIG. 1, the conversion device 10 according to the embodiment includes a solar cell module 1 having multiple 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.

[Solar cell module]
Next, a solar cell module 1 according to an embodiment will be described. FIG. 2 is a diagram showing an example of a cross section of a main part of a solar cell module according to an embodiment. In FIG. 2 and subsequent figures, 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 subsequent figures. The xy plane direction corresponds to the surface direction of the solar cell 110, the transparent layer 140, etc., which will be described later. Hereinafter, unless otherwise specified, "planar view" refers to viewing in the z-axis direction (e.g., the z-axis negative direction). "Side view" refers to viewing in the x-axis direction or the y-axis direction (e.g., the y-axis positive direction).

As shown in FIG. 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 microscopic structure 150 integrated on the solar cells 110-1 to 110-3. The solar cells 110-1 to 110-3 and the solar cell 110-4 described below are collectively referred to as solar cell 110.

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.

The solar cells 110-1 to 110-3 each have a p-type semiconductor layer 160-1 to 160-3 and an n-type semiconductor layer 170-1 to 170-3 as a photoelectric conversion unit. Each of the solar cells 110-1 to 110-3 has a material having a high light absorption rate in the corresponding wavelength bands _B1 , _B2 , and _B3 as a photoelectric conversion unit. An anti-reflection layer 180 is laminated on the n-type semiconductor layers 170-1 to 170-3. The solar cells 110-1 to 110-3 each 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.

Examples of materials constituting the photoelectric conversion unit include silicon-based materials such as x-Si and a-Si:H, compound semiconductors such as GaAs, InAs, GaInAs, Zn ₃ P ₂ , Cu ₂ S, CuInSe ₂ , CuIn _1-x GaxSe ₂ , InP, CdTe, and CdS, organic semiconductors, photocatalytic materials (such as titanium oxide), and dye-sensitized materials consisting of dye molecules.

The wavelength separation lens 120 separates the incident light (for example, sunlight) into wavelength bands (for example, wavelength bands B ₁ , B ₂ , B ₃ ) and focuses the light on each of the solar cell 110-1 to 110-3. The wavelength separation lens 120 focuses the wavelength band B ₁ of the incident light on the solar cell 110-1. The wavelength separation lens 120 focuses the wavelength band B ₂ of the incident light on the solar cell 110-2. The wavelength separation lens 120 focuses the wavelength band B ₃ of the incident light on the solar cell 110-3. The wavelength bands (B _k ) separated by the wavelength separation lens 120 correspond to bands obtained by arbitrarily dividing the spectral wavelength band of sunlight. Alternatively, the wavelength separation lens 120 may be designed so that the wavelength bands separated by the wavelength separation lens 120 are adapted to the absorption spectrum of the existing solar cell 110.

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

The transparent layer 140 is a low-refractive index transparent layer made of a material such as SiO ₂ (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 (e.g., an air layer (refractive index n=1.00)), but the solar cell module 100 may have a configuration in which the transparent layer 140 covers the space between the wavelength separation lens 120 and the solar cell 110.

The multiple structures 150 are arranged so as to separate the incident light into each of the predetermined wavelength bands and focus the light on the solar cell 110-110-3 corresponding to each wavelength band. The multiple structures 150 are arranged in the plane direction of the transparent layer 140 with a period equal to or less than the wavelength of the incident light. The multiple structures 150 are made of columnar structures of constant height, and their in-plane shapes (upper and lower surfaces) have four-fold rotational symmetry. In the embodiment, the occurrence of polarization dependency is suppressed by making the shape of the structures 150 four-fold rotational symmetry.

Each of the plurality of structures 150 is formed from a material such as _TiO2 or SiN having a refractive index higher than that of the transparent layers 130 and 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 and 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 realizing light concentration on each of the solar cell arrays 110-1 to 110-3, and the structures 150 are arranged according to an optical phase delay distribution for realizing light concentration on each of the solar cell arrays 110-1 to 110-3.

In this way, the solar cell module 100 separates the incident light into a plurality of wavelength bands (e.g., wavelength bands _B1 , _B2 , _B3 ) and receives the light with solar cell cells 110 (e.g., 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 and increases efficiency compared to conventional solar cell modules.

Each solar cell 110 (e.g., 110-1 to 110-3) may be 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 a conventional tandem solar cell, each solar cell 110 having an optical absorption spectrum corresponding to each of the separated wavelength bands can be used simultaneously. Therefore, compared to conventional solar cells, the solar cell module 100 can efficiently absorb and photoelectrically convert light in multiple wavelength bands, and compared to conventional tandem solar cells, the difficulty of fabrication can be significantly reduced, and fabrication costs can also be reduced.

There is no limitation on 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 on a plurality of solar cells 110. For example, the wavelength separation lens 120 focuses light of wavelength band _B1 on the solar cell 110-1, but when a solar cell 110-3 is disposed at the position of the solar cell 110-1, the wavelength separation lens 120 may be designed to focus light of wavelength band _B3 on the solar cell 110-3 instead of wavelength band _B1 . The wavelength separation lens 120 and the solar cell 110 may be arrayed, or may be composed of one wavelength separation lens 120 and a plurality of solar cells 110 as shown in FIG. 2.

[First Configuration Example]
Next, a solar cell module 100-1 having a first configuration example will be described. FIG. 3 is a diagram showing a schematic arrangement of solar cell cells 110 when the solar cell module 100-1 according to the embodiment is viewed in plan. 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 a-a' 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 FIG. 4 and FIG. 5, arrows typically indicate light incident on the solar cell module 100-1.

In the solar cell module 100-1, four solar cells having optical absorption spectra corresponding to the 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 Fig. 4 and Fig. 5, a wavelength separation lens 120-1 is arranged on the solar cells 110-1 to 110-4. Also, for example, one wavelength separation lens 120-1 may face the four solar cells 110-1 to 110-4 directly below it.

The solar cell 110-4 absorbs light in the 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 is laminated on the n-type semiconductor layer 170-4, and has 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.

The wavelength separation lens 120-1 separates the incident light into wavelength bands B ₁ , B ₂ , B ₃ , and B ₄ and focuses the separated light onto the solar cells 110-1 to 110-4 having optical absorption spectra suited to the respective wavelength bands B ₁ , B ₂ , B ₃ , and B ₄ .

The wavelength separation lens 120-1 focuses light in wavelength band _B1 from the incident light onto the solar cell 110-1. The wavelength separation lens 120-1 focuses light in wavelength band _B2 from the incident light onto the solar cell 110-2. The wavelength separation lens 120-1 focuses light in wavelength band _B3 from the incident light onto the solar cell 110-3. The wavelength separation lens 120-1 focuses light in wavelength band _B4 from 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.

The wavelength separation lens 120-1 is provided so as to cover the solar cell 110-1 to 110-4. An example of the wavelength separation lens 120-1 is a metasurface. The metasurface is composed of multiple microstructures (corresponding to the structure 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 separation lens 120-1 can control the phase and light intensity according to the characteristics of the light (wavelength, polarization, and angle of incidence) simply by changing the parameters of this structure 150. Furthermore, a three-dimensional structure provides greater design freedom than a two-dimensional structure.

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

In this example, the wavelength separation function of the wavelength separation lens 120-1 separates the incident light into wavelength bands _B1 , _B2 , _B3 , and _B4 . The light in the wavelength bands _B1 , _B2 , _B3 , and _B4 is focused on the solar cell 110-1 to 110-4 corresponding to the wavelength bands _B1 , _B2 , _B3 , and _B4 , respectively, by the lens function of the wavelength separation lens 120-1.

FIGS. 6 to 9 are schematic diagrams showing the concentration of light onto solar cells 110-1 to 110-4 in the solar cell module 100-1 shown in FIG. 3.

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 allow light in wavelength band _B1 to be concentrated on the solar cell 110-1 corresponding to the wavelength band _B1 . In this example, not only light above the solar cell 110-1 (positive direction of the z-axis) but also light around the solar cell 110-1 is concentrated on the solar cell 110-1. That is, 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.

7, 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 . 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.

In the solar cell module 100-1, the wavelength separation function and lens function of the wavelength separation lens 120-1 concentrate light in wavelength band _B3 on the solar cell 110-3 corresponding to wavelength band _B3 , as shown by the arrow 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.

9, 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 . 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.

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 with the solar cells 110-1 to 110-4 is concentrated onto the solar cells 110-1 to 110-4.

The wavelength separation lens 120-1 may focus light of the same wavelength band on a plurality of solar cells 110. The wavelength separation lens 120-1 focuses light of wavelength band _B2 on the solar cell 110-2, but when the solar cell 110-4 is disposed at the position of the solar cell 110-2, the lens may be designed to focus light of wavelength band _B4 on the solar cell 110-4 instead of wavelength band _B2 .

[Second Configuration Example]
Next, a solar cell module 100-2 having a second configuration example will be described. Fig. 10 is a diagram showing a schematic arrangement of solar cells 110 when the solar cell module 100-2 according to the embodiment is viewed in plan. 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 c-c' in Fig. 10. In Fig. 11, arrows typically indicate light incident on the solar cell module 100-2.

In the solar cell module 100-2, three solar cells having light absorption spectra corresponding to the wavelength bands _B1 , _B2 , and _B3 , respectively, are arranged in parallel as shown in Fig. 10 to form one unit U1-2. 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.

The wavelength separation lens 120-2 separates the incident light into wavelength bands B ₁ , B ₂ , and B ₃ and focuses the separated light onto the solar cells 110-1 to 110-3 having optical absorption spectra suited to the respective wavelength bands B ₁ , B ₂ , and B ₃ .

The wavelength separation lens 120-2 focuses light in wavelength band _B1 from the incident light onto the solar cell 110-1. The wavelength separation lens 120-2 focuses light in wavelength band _B2 from the incident light onto the solar cell 110-2. The wavelength separation lens 120-2 focuses light in wavelength band _B3 from 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.

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

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 the incident light into wavelength bands _B1 , _B2 , and _B3 . The light in the wavelength bands _B1 , _B2 , and _B3 is focused on the solar cell 110-1 to 110-3 corresponding to the wavelength bands _B1 , _B2 , and _B3 , respectively, by the lens function of the wavelength separation lens 120-2.

FIGS. 12 to 14 are schematic diagrams showing the concentration of light onto solar cells 110-1 to 110-3 in the solar cell module 100-2 shown in FIG. 10.

In the solar cell module 100-2, as shown by the arrows in Fig. 12, light in wavelength band _B1 is concentrated on the solar cell 110-1 corresponding to wavelength band _B1 . In this example, not only light above the solar cell 110-1 (positive direction of the z-axis) 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.

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.

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.

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 the wavelength bands _B1 , _B2 , and _B3 of the incident light in the opposing areas with the solar cells 110-1 to 110-3 is concentrated onto the solar cells 110-1 to 110-3.

The wavelength separation lens 120-2 may focus light of the same wavelength band on a plurality of solar cells 110. The wavelength separation lens 120-2 focuses light of wavelength band _B1 on the solar cell 110-1, but when the solar cell 110-3 is disposed at the position of the solar cell 110-1, the lens may be designed to focus light of wavelength band _B3 on the solar cell 110-3 instead of wavelength band _B1 .

[Structural example of wavelength separation lens]
2, the wavelength separation lens 120 is formed on the bottom surface of the transparent layer 140, but this is not limited to this. Figures 15 to 24 are diagrams each showing a schematic view of another example of a part of a cross section of the wavelength separation lens 120 according to the embodiment.

As shown in the wavelength separation lens 120A in FIG. 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.

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

In the wavelength separation lens 120B, structures 150-1 and 150-2 are formed on the upper surface of the transparent layer 140 and inside the transparent layer 140, respectively. In the wavelength separation lens 120C, structures 150-1 to 150-3 are formed in a total of three layers, one layer on the upper surface of the transparent layer 140 and two layers inside the transparent layer 140. Structure 150-1 is supported on the upper surface of the lower transparent layer 140. The material of structures 150-1 to 150-3 may be the same within a layer, or may be the same in all layers. The material of 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 structures 150-1 to 150-3 may be the same within a layer and/or in all layers, or may be different for each location and/or for each layer.

Also, as shown in wavelength separation lens 120D in FIG. 18, wavelength separation lens 120E in FIG. 19, and wavelength separation lens 120G in FIG. 20, the structure 150 may be formed inside the transparent layer 140. In wavelength separation lens 120D, one layer of structure 150 is formed inside the transparent layer 140. In wavelength separation lens 120E, two layers of structures 150-1 and 150-2 are formed inside the transparent layer 140. In wavelength separation lens 120G, three layers of structures 150-1 to 150-3 are formed inside the transparent layer 140.

Furthermore, as shown in the wavelength separation lens 120H in FIG. 21 and the wavelength separation lens 120I in FIG. 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 separation 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 separation 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 separation lens 120H and 150-3 of the wavelength separation lens 120I are supported by the transparent layer 140 above.

Also, as shown in the wavelength separation lens 120J of FIG. 23 and the wavelength separation lens 120K of FIG. 24, the structures 150 may be formed on the top and bottom surfaces of the transparent layer 140. In the wavelength separation lens 120J, structures 150-1 and 150-2 are formed on the top surface and bottom surface of the transparent layer 140, respectively. In the wavelength separation 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 separation lens 120J and the wavelength separation lens 120K are supported by the transparent layer 140 below. The structures 150-2 of the wavelength separation lens 120J and the structures 150-3 of the wavelength separation lens 120K are supported by the transparent layer 140 above.

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

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

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

The wavelength separation lens 120 is realized by utilizing the wavelength dispersion characteristics of the amount of optical phase delay that the fine columnar structure (structure 150) imparts to the incident light.

The structures 150 of each layer are 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 the difficulty of fabrication, the structure 150 is preferably a structure having a constant height (length in the z-axis direction) _hlayer within the plane. Note that the height of the structure 150 may differ for each layer.

The bottom and top surfaces of the structure 150 have a four-fold rotationally symmetric shape. This shape suppresses the occurrence of polarization dependency.

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

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

This optical phase delay amount φ _layer differs depending on the wavelength λ of the light, so that the same structure 150 can impart different optical phase delay amounts φ _layer depending on the wavelength band of the light.

Furthermore, it is known that the effective refractive index _neff of the optical waveguide is greatly dependent on the cross-sectional shape of the structure 150, and has a value of _n0 < _neff < _n1 .

Moreover, the effective refractive index n _eff of the optical waveguide also differs depending on the wavelength λ of the light, and the degree of this differs greatly depending on the cross-sectional shape of the structure 150 .

Therefore, by using the columnar structures 150 having various cross-sectional shapes, it is possible to set various combinations of the phase delay amount φ _layer according to the wavelength λ of light.

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

In order to prevent the light diffraction phenomenon that causes a decrease in efficiency, it is desirable to set the arrangement period P of the structures 150 as shown in formula (2), where λ _min is the shortest central wavelength of the desired light receiving wavelength band. Note that n ₀ is the refractive index of the transparent layer 140 located on the transmission side.

Next, we will explain the advantages of multi-layering the structure 150. In the case of a single-layer structure 150, it is preferable that the height _h1 of the single-layer structure 150 has an optical phase delay amount φ _layer of 2π or more, so that it is preferable to set it as shown in formula (3) when the desired center wavelength in the wavelength range on the longest wavelength side of the wavelength range to be separated is _λr .

In the case of the visible light region, when _n1 is the refractive index of the SiN of the structure 150 and _n0 is the refractive index of the _SiO2 of the transparent layers 130 and 140, it is desirable that the height _h1 of the single-layer structure 150 be 1060 nm or more.

In this case, if the arrangement period P of each structure 150 is set to be equal to or shorter 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 , then it is necessary to set the aspect ratio of the structures 150 to 3.8 or more.

The cross-sectional dimension of the actual structure 150 is made smaller than the structural period P in order to reduce optical coupling with adjacent structures 150, and so if the maximum dimension is 200 nm, the aspect ratio will be 5.3 or more. Furthermore, some structures 150 having smaller cross-sectional dimensions are used in order to control the effective refractive index n _eff of the optical waveguide, and if the minimum is 80 nm, the aspect ratio will be about 13.3.

　In order to fabricate such high aspect ratio microstructures using conventional semiconductor processes, advanced fabrication techniques are generally required.

In contrast, by dividing the structure 150 into a plurality of layers in the height direction, the aspect ratio of the fine structure 150 can be suppressed while ensuring the required optical phase delay amount φ _layer in the sum of the layers.

For example, in the case of the visible light region, when a two-layer structure 150 is formed with n ₁ being the refractive index of the SiN of the structure 150 and n ₀ being the refractive index of the SiO ₂ of the transparent layer 140, the height h _{1, 2} of the structure 150 of each layer can be about half that of a one-layer structure, for example, 530 nm or less. Therefore, the aspect ratio can be reduced to about half. Also, when a three-layer structure 150 is formed, the aspect ratio can be reduced to one-third in the same manner.

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.

At this time, as is clear from the above formula, by forming the structure 150 into a plurality of layers, n _eff and its wavelength dispersion can be arbitrarily changed by the cross-sectional dimensions for each layer of the structure 150. That is, when the structure 150 is formed into a plurality of layers, it becomes possible to set a wider variety of combinations of the optical phase delay amount φ _layer according to the wavelength λ of light, compared with the case where the structure 150 is a single layer, and it becomes possible to improve the wavelength separation efficiency and the light collection efficiency.

[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 with similar design guidelines.

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

The structure 160 is a columnar structure extending in the z-axis direction, and is formed on the bottom surface of the transparent layer 140 (e.g., _SiO2 (refractive index _neff = 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).

The arrangement period of the structures 160 is denoted by P. It is desirable to set the arrangement period P as shown in formula (2) so that no diffracted light occurs on the transmission side. Here, the shortest wavelength λ _min of the light receiving wavelength band is set to 410 nm, n ₀ is set to 1.45, and the arrangement period P is set to 280 nm.

The height h _layer (length in the z-axis direction) of the structure 150 is constant. The height h _layer is preferably such 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. If the number of layers is L and the desired center wavelength in the wavelength range on the longest wavelength side of the wavelength range to be separated is λ _r , it is desirable to set the height h _layer as shown in formula (4).

Here, L=2, and from equation (4), the height of each layer is h _1,2 =850 nm.

By designing the cross-sectional shape of the structure 160 and its dimensional parameters (width of the structure), it is possible to realize various combinations of different phase values at multiple wavelengths.

In this case, as is clear from formula (1), by changing the cross-sectional shape and dimensional parameters for each layer, the effective refractive index _neff and wavelength dispersion of the optical waveguide can be changed for each layer.

Furthermore, when the structure 150 has multiple layers, considering the optical phase delay amount φ _layer as the sum of each layer makes it possible to have a wider variety of combinations of phase values, which leads to an increased degree of freedom in designing different lens functions for each wavelength range.

The cross-sectional shape of the structure 150 is preferably a four-fold rotationally symmetric shape in order 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 formed by rotating a columnar structure having a square with a cross and square holes by 45° in-plane, as shown in FIGS. 27 to 30.

In addition, in Figures 27 to 30, a columnar structure having a square with a cross-shaped and square hole is rotated by 45° in-plane as the cross-sectional shape of the structure 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 the designed spatial phase distribution can be easily reproduced.

When the structure 150 is made up of 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 a layer, it is desirable to set the distance to about the wavelength or less. Also, the structures 150 for each layer may be connected. In other words, the distance between layers may be zero.

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

[Design example 1 of wavelength separation lens]
Next, a design example of the wavelength separation lens will be described. In this example, for example, the wavelength separation lens 120-1 of the solar cell module 100-1 of the first configuration example shown in Figures 3 to 6 is assumed. The number of wavelength band divisions of the wavelength separation lens 120-1 is 4. Note that the same design as below can be applied to other numbers of wavelength divisions.

In lens design, the cross-sectional shape and arrangement of the structure 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 or multiple layered columnar structure 150. In this example, a structure 150 composed of SiN is used, and by utilizing the wavelength dispersion characteristics of the optical phase delay, a different phase distribution is designed for each central wavelength of each wavelength band from 400 nm to 1200 nm, resulting in the wavelength separation lens 120-1.

The ideal optical phase delay distribution of unit U1-1 (solar cell 110-1 to 110-4) is shown. FIG. 32 is a diagram showing an ideal optical phase delay distribution when the central wavelength is 500 nm. FIG. 33 is a diagram showing an ideal optical phase delay distribution when the central wavelength is 650 nm. FIG. 34 is a diagram showing an ideal optical phase delay distribution when the central wavelength is 800 nm. FIG. 35 is a diagram showing an ideal optical phase delay distribution when the central wavelength is 1000 nm. Note that in FIG. 32 to FIG. 35, the central positions of the four solar cell 110-1 to 110-4 (unit U1-1) correspond to x=0, y=0.

The parameters of the design example are as follows:
Solar cell size: 15mm x 15mm
Focal length: 15mm
Central wavelengths of each wavelength band: Wavelength band _B1 : 500 nm, Wavelength band _B2 : 650 nm, Wavelength band _B3 : 800 nm, Wavelength band _B4 : 1000 nm

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

In the above equation (5), λ _d is the central wavelength (design wavelength), x _f , y _f and z _f are the focusing positions, n ₂ is the refractive index of the lower transparent layers 130 and 140, and C is an arbitrary constant.

32 to 35, a phase distribution was set that provides the following light collection positions for wavelength bands _B1 , _B2 , _B3 , and _B4 in accordance with the positions of the four solar cells 110-1 to 110-4. Note that the central positions of the four solar cells 110-1 to 110-4 (unit U1-1) correspond to x=0, y=0.
Wavelength band _B1 : _xf = +7.5 mm, _yf = -7.5 mm, _zf = 15 mm
Wavelength band _B2 : _xf = +7.5 mm, _yf = +7.5 mm, _zf = 15 mm
Wavelength band _B3 : _xf = -7.5 mm, _yf = -7.5 mm, _zf = 15 mm
Wavelength band _B4 : _xf = -7.5 mm, _yf = +7.5 mm, _zf = 15 mm

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 central wavelength is symmetrical (together with adjacent lenses) in the left and right directions and up and down around the focusing position. The constant C may be optimized for each wavelength so that the error in the phase distribution is minimized.

Then, from the amount of optical phase delay at each wavelength that the composition structure has, the structure that best matches the phase distribution of the above four wavelengths, i.e., the structure 150 with 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.

[Design example 2 of wavelength separation lens]
Next, another design example of the wavelength separation lens will be described. In this example, for example, the wavelength separation lens 120-2 of the solar cell module 100-2 of the second configuration example shown in Figures 10 and 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 wavelength division numbers.

In lens design, the cross-sectional shape and arrangement of the structure 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 or multiple layered columnar structure 150. In this example, a structure 150 composed of SiN is used, and by utilizing the wavelength dispersion characteristics of the optical phase delay, a different phase distribution is designed for each central wavelength of each wavelength band from 400 nm to 1200 nm, and wavelength separation lens 120-2 is realized.

The ideal optical phase delay distribution of unit U1-2 (solar cell 110-1 to 110-3) is shown. Figure 36 is a diagram showing the ideal optical phase delay distribution when the central wavelength is 500 nm. Figure 37 is a diagram showing the ideal optical phase delay distribution when the central wavelength is 650 nm. Figure 38 is a diagram showing the ideal optical phase delay distribution when the central wavelength is 1000 nm. Note that in Figures 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.

The parameters of the design example are as follows:
Solar cell size: 15mm x 15mm
Focal length: 30mm
Central wavelengths of each wavelength band: Wavelength band _B1 : 500 nm, Wavelength band _B2 : 650 nm, Wavelength band _B3 : 1000 nm

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

In the above equation (6), λ _d is the central wavelength (design wavelength), x _f , y _f and z _f are the focusing positions, n ₂ is the refractive index of the lower transparent layers 130 and 140, and C is an arbitrary constant.

36 to 38, a phase distribution was set that provides the following light collection positions for wavelength bands _B1 , _B2 , and _B3 in accordance with the positions of three solar cells 110-1 to 110-3. Note that the central positions of the four solar cells 110-1 to 110-3 (unit U1-2) correspond to x=0, y=0.
Wavelength band B ₁ : x _f = -15 mm, y _f = 0 mm, z _f = 30 mm
Wavelength band _B2 : _xf = 0 mm, _yf = 0 mm, _zf = 30 mm
Wavelength band _B3 : _xf = +15 mm, _yf = 0 mm, _zf = 30 mm

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 central wavelength is symmetrical (together with adjacent lenses) in the left and right directions and up and down around the focusing position. The constant C may be optimized for each wavelength so that the error in the phase distribution is minimized.

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

[Effects of the embodiment]
A conventional solar cell will be described. Fig. 39 is a diagram showing a schematic 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 part using only a single material (e.g., Si). Fig. 40 is a diagram showing a schematic diagram of 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.

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 resulting from the band gap of the material (see region R11).

Figure 41 is a diagram that shows a schematic diagram of another example of a cross section of a main part of a conventional solar cell module. Figure 41 shows a tandem solar cell module having a photoelectric conversion section that uses a multi-junction compound semiconductor in which multiple materials with different bandgaps are stacked. Figure 42 is a diagram that shows a schematic diagram of the wavelength dependence of the light intensity radiated/absorbed by the solar cell module shown in Figure 41. Curve C1 in Figure 42 shows the spectrum of sunlight.

As shown in Figure 42, a tandem solar cell module can absorb and photoelectrically convert 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 how much the photoelectric conversion efficiency can be improved. In addition, with tandem solar cells, the materials that can be bonded as multi-junction compound semiconductors are limited, and they are difficult to fabricate.

Figure 43 is a diagram showing the wavelength dependency of the light intensity radiated/absorbed by the solar cell module 100 shown in Figure 2. As shown in Figure 43, the solar cell module 100 according to the embodiment can absorb and photoelectrically convert 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 because it has fewer material constraints than a tandem solar cell module. 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 it is difficult to use this material in a tandem solar cell module. In this case, as shown in region R23, it is believed that the absorption rate of long wavelength band light is also higher than that of a tandem solar cell module, and high photoelectric conversion efficiency can be achieved.

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

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, with the solar cell module 100, solar cells 110 each made of materials that would be difficult to join together in a tandem solar cell can be used simultaneously, and it is expected that the photoelectric conversion efficiency can be maximized by using a material that can more efficiently absorb and convert sunlight into electricity in the photoelectric conversion section.

In addition, in the solar cell module 100, each solar cell 110 can be a photoelectric conversion unit using a single material that is suitable for each wavelength band, making it much easier to fabricate than a tandem solar cell, leading to reduced manufacturing costs.

In addition, when the structure 150 of the wavelength separation lens 120 of the solar cell module 100 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, which increases the light control and allows for more efficient wavelength band separation.

In the solar cell module 100, there is no limit to the number of wavelength bands that can be separated, and the effect can be achieved as long as there are multiple bands. In addition, in the solar cell module 100, light of the same wavelength band may be concentrated on multiple solar cell cells 110, allowing for a high degree of freedom in design.

The conversion device 10 described with reference to FIG. 1 etc. is also one aspect of the present disclosure. The conversion device 10 according to the embodiment has the solar cell module 100 described above, and therefore has improved photoelectric conversion efficiency and reduced manufacturing costs compared to the conventional technology.

LIST OF SYMBOLS 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 to 150-3 Structure 160-1 to 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 (5)

A plurality of solar cells, each of which absorbs light in a respective predetermined wavelength band 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 shorter than the wavelength of incident light, the plurality of structures being arranged so as to separate the incident light into each of predetermined wavelength bands and concentrate the light on the solar cells corresponding to each wavelength band;
A solar cell module comprising: 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 plan view;
The solar cell module according to claim 1 , wherein the plurality of structures have cross-sectional shapes set according to an optical phase delay distribution for achieving the light concentration, and are arranged according to the optical phase delay distribution for achieving the light concentration. The solar cell module according to claim 1, characterized in that the cross-sectional shape of each of the plurality of structures is a four-fold rotationally symmetric shape. The solar cell module according to claim 1, characterized in that the multiple structures are formed in multiple layers on or within the transparent layer along the stacking direction of the transparent layer. A solar cell module according to any one of claims 1 to 4,
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:

Images