Photovoltaic module, flying vehicle

Abstract

To provide a photovoltaic module that has improved efficiency in supplying power through light irradiation, and an aircraft equipped with the photovoltaic module.SOLUTION: An optical element includes a photoelectric conversion element having a light-receiving surface and generating electricity when light is incident on the light-receiving surface, and an optical element having an incident surface located outside the light-receiving surface when viewed in a first direction perpendicular to the light-receiving surface of the photoelectric conversion element, and having a refractive portion that refracts at least a portion of the light incident on the incident surface so as to travel toward the light-receiving surface.SELECTED DRAWING: Figure 4A

Description

Technical Field

[0001] The present invention relates to a photovoltaic module and an aircraft equipped with the photovoltaic module.

Background Art

[0002] In recent years, remarkable technological developments have been made in aircraft, and various companies and research institutions are intensively studying and developing the improvement of aircraft performance and systems using aircraft. In particular, drones are applied in various fields such as transportation, high-place inspection, and video shooting.

[0003] Toward the realization of each aspect related to aircraft as described above, an aircraft such as a drone is expected to be able to maintain flight for a long time. As a method for realizing long-duration flight, for example, increasing the capacity of a battery for rotationally driving a propeller can be considered.

[0004] However, when mounting a large-capacity battery, a larger battery is required, which may lead to an increase in the weight of the entire aircraft. Therefore, with this method, instead of increasing the battery capacity, the power consumption per unit time increases, making it difficult to realize long-duration flight as a result. Thus, recently, a method of supplying power to an aircraft during flight has been proposed. Patent Document 1 and Patent Document 2 below disclose a system that uses a photoelectric conversion element mounted on an aircraft and a light source that irradiates light toward the aircraft while tracking the flight path of the aircraft to supply power using the photoelectric effect.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Here, the inventor who is researching a system using a flying object has been earnestly studying to achieve more efficient photovoltaic power supply. As a result, even if the flying object could accurately track and irradiate light, the inventor noticed that there is a relatively large amount of light that does not contribute to photovoltaic power generation.

[0007] More specifically, a photovoltaic conversion element mounted on a flying object inevitably has a portion where light for photovoltaic conversion is incident (hereinafter referred to as the "light-receiving surface") and a portion other than the light-receiving surface (hereinafter sometimes referred to as the "non-light-receiving surface") when viewed from the light source side. And the light emitted from the light source and incident on the non-light-receiving surface rather than the light-receiving surface is reflected, scattered, or absorbed on the non-light-receiving surface, so it hardly contributes to photovoltaic conversion.

[0008] That is, simply irradiating the light for power supply toward the light-receiving surface of the flying object will result in a relatively large amount of light that does not contribute to photovoltaic conversion, so the power supply efficiency of the entire system will be significantly lower than expected.

[0009] In view of the above problems, an object of the present invention is to provide a photovoltaic module with higher power supply efficiency by light irradiation and a flying object equipped with the photovoltaic module.

Means for Solving the Problems

[0010] The photovoltaic module of the present invention has a light-receiving surface and a photovoltaic conversion element that generates electricity when light is incident on the light-receiving surface, and an optical element having an incident surface located outside the light-receiving surface when viewed in a first direction orthogonal to the light-receiving surface of the photovoltaic conversion element, and having a refracting portion that refracts at least a part of the light incident on the incident surface so as to travel toward the light-receiving surface.

[0011] In the case of the photovoltaic module with the above configuration, if left as it is, part of the light that reaches the outside of the light-receiving surface of the photoelectric conversion element, that is, the non-light-receiving surface, is refracted by the optical element so as to travel toward the light-receiving surface. That is, in the photovoltaic module with the above configuration, since the amount of light incident on the light-receiving surface of the photoelectric conversion element increases, the power supply efficiency is enhanced compared with the conventional configuration.

[0012] In the above photovoltaic module, the refractive portion of the optical element may be constituted by a diffractive optical element.

[0013] Furthermore, in the above photovoltaic module, the refractive portion of the optical element may be constituted by a Fresnel lens.

[0014] Furthermore, in the above photovoltaic module, the optical element may include a first region and a second region including diffractive surfaces with different convergence points in the radial direction centered on the optical axis of the Fresnel lens.

[0015] As specific examples of the diffractive optical element, a diffraction grating having a plurality of grooves formed on the incident surface and a Fresnel lens divided into regions on concentric circles and formed such that the refraction angle varies according to the position where light is incident are assumed.

[0016] The diffractive optical element has a feature that it is relatively easy to configure it thinly without a large change in the overall thickness according to the desired refractive index like a lens or the like, so that it is easy to configure the element itself lightly. For this reason, when mounted on an aircraft, in particular, since it is required to reduce the weight of the entire photovoltaic module, it is preferable to adopt the photovoltaic module with the above configuration.

[0017] In the case of a Fresnel lens having only the first region, when viewed in the first direction, light within a certain range can be made to travel toward the light-receiving surface of the photoelectric conversion element, but light outside of this range may not be able to reach the light-receiving surface of the photoelectric conversion element. In particular, when the area where the power supply light is incident is large relative to the area of the light-receiving surface of the photoelectric conversion element, relatively more light is wasted.

[0018] Therefore, as described above, by providing a Fresnel lens including the first region and the second region, compared to a Fresnel lens having only the first region, more light traveling outside the light-receiving surface of the photoelectric conversion element can be made to travel toward the light-receiving surface.

[0019] Also, in the above photovoltaic module, The refractive portion of the optical element may have a polygonal shape when viewed in the first direction, and the diffractive optical element may be a diffraction grating.

[0020] Furthermore, in the above photovoltaic module, The refractive portion of the optical element may be configured to have a hexagonal shape when viewed in the first direction.

[0021] Light emitted from a light source and directly irradiated onto a predetermined surface generally tends to have a shape close to a circle. For this reason, it is preferable that the shape of the outer edge of the optical element when viewed in the optical axis direction (first direction) is circular or close to a circular shape. However, when the shape when viewed in the optical axis direction is circular or close to a circular shape, a gap is likely to occur between the optical element and other members or between optical elements, and light traveling toward the gap is likely to be wasted.

[0022] Therefore, considering the perspective of approaching the shape of the light incident on the incident surface and the perspective of arranging the optical elements without gaps, it is preferable that the outer edge of the optical element exhibits a polygonal shape when viewed in the first direction, more preferably a square shape or a hexagonal shape, and particularly preferably a hexagonal shape. Furthermore, a single optical component may be configured by combining a plurality of optical elements having different shapes.

[0023] The above photovoltaic module Regarding the first direction, the separation distance between the light-receiving surface of the photoelectric conversion element and the optical element may be 2.5 mm to 3.0 mm.

[0024] In the above photovoltaic module, Regarding the first direction, the thickness of the thickest part of the optical element may be 0.3 mm to 1.3 mm.

[0025] The refractive index of the optical element often depends on the size of the irregularities provided on the incident surface, the exit surface, or both surfaces of the optical element. In particular, when attempting to achieve a high refractive index, the irregularities formed on the incident surface or the exit surface of the optical element tend to become large, so there is a need to increase the thickness of the optical element in the first direction. Such circumstances lead to an increase in the weight of the optical element.

[0026] In addition, if a sufficient separation distance WD between the photoelectric conversion element and the optical element is ensured, the refractive index required for the optical element becomes relatively small, and the optical element can be configured to be relatively thin, so an increase in the weight of the optical element can be suppressed. However, if the separation distance is too large, the overall size of the photovoltaic module increases, and there is a need to control the refractive index to an extremely small value, which may cause problems with the processing accuracy of the optical element.

[0027] Considering these circumstances, the separation distance between the photoelectric conversion element and the optical element is preferably 2.5 mm to 3.0 mm, and more preferably 2.6 mm to 2.9 mm. Further, the thickness of the thickest portion in the first direction of the optical element is preferably 0.3 mm to 1.3 mm, and more preferably 0.4 mm to 1.2 mm. Note that the thickness of the optical element means the thickness of the portion through which light passes, and does not include portions such as those for simply fixing these elements.

[0028] In the above photovoltaic module, The optical element may have an AR coating layer formed on the light incident surface and the light exit surface.

[0029] With the above configuration, the amount of light reflected by the light incident surface and the light exit surface of the optical element can be suppressed, so that the power supply efficiency by light irradiation can be further increased. Note that the AR coating layer is preferably a layer having a structure and shape that reduces the reflectance with respect to the peak wavelength of light incident on the target surface to 1% or less.

[0030] The above photovoltaic module may include a holding member disposed between an element substrate on which a plurality of the photoelectric conversion elements are arranged on one main surface and the optical element, and holding the photoelectric conversion element and the optical element in a separated state.

[0031] The flying object of the present invention includes the above photovoltaic module, a drive mechanism connected to the photovoltaic module, and a propeller driven by the drive mechanism.

Effects of the Invention

[0032] According to the present invention, a photovoltaic module with higher power supply efficiency by light irradiation and a flying object equipped with the photovoltaic module are realized.

Brief Description of the Drawings

[0033]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4A

Figure 4B

Figure 5A

Figure 5B

Figure 6

Figure 7A

Figure 7B

Embodiments for Carrying Out the Invention

[0034] Hereinafter, the photovoltaic module and the flying object of the present invention will be described with reference to the drawings based on the photovoltaic power generation system using these. Note that each of the following drawings is schematically illustrated, and the dimensional ratios and the number of elements on the drawings do not necessarily match the actual dimensional ratios and the number.

[0035] [Photovoltaic Power Generation System 1] FIG. 1 is an overall view schematically showing an embodiment of the photovoltaic power generation system 1. As shown in FIG. 1, the photovoltaic power generation system 1 of the present embodiment includes a light source unit 2 and a flying object 3.

[0036] As shown in FIG. 1, the optical power supply system 1 is a system that maintains the flight of the flying object 3 by supplying power to the flying object 3 with the light L1 emitted from the light source unit 2. Since the optical power supply system 1 can keep the flying object 3 flying for a long time, for example, it is assumed to be applied to a monitoring system for the purpose of crime prevention or traffic information collection, a management system for forests or farmlands, etc.

[0037] Note that the operation mode of the flying object 3 may be a mode in which it stays in the irradiation area of the light L1 emitted from the light source unit 2 only during power supply, or a mode in which it always stays in the irradiation area of the light L1 emitted from the light source unit 2.

[0038] The light source unit 2 has a light source (not shown) accommodated therein, and is configured to emit the light L1 from the emission part 2a toward the flying object 3.

[0039] The light source mounted on the light source unit 2 in this embodiment is a semiconductor laser element. Since the height at which the flying object 3 flies is arbitrarily set, in some cases, it is also assumed that the flying object 3 maintains flight at a height of 100 m or more. Then, from the viewpoint of efficiently supplying power to the flying object 3, the light L1 is required to have high directivity. For this reason, the light L1 emitted from the light source unit 2 is preferably laser light.

[0040] Also, the light L1 may be any of ultraviolet light, visible light, and infrared light. However, considering the case where it is assumed to be emitted substantially constantly outdoors, etc., it is preferably visible light or infrared light that has relatively little influence on humans and animals.

[0041] Note that, for example, considering not to unnecessarily brighten the surroundings at night, etc., the light L1 is preferably infrared light. Also, when there are circumstances such as wanting to visually confirm whether the light L1 is being emitted or wanting to grasp from which position the light L1 is being emitted, the light L1 is preferably visible light.

[0042] Furthermore, the light source unit 2 may be configured to be able to change the installation location. For example, a plurality of dedicated attachments are fixed to the ground, and by attaching the light source unit 2 to an attachment at an arbitrary position, the power supply point of the flying object 3 can be changed, or it is fixed to the upper surface of a vehicle, and the power supply point of the flying object 3 is changed by the movement of the vehicle. Etc. are also assumed.

[0043] [Flying object 3] FIG. 2A is a cross-sectional view schematically showing the internal structure of the flying object 3 when viewed from the +Y side, and FIG. 2B is a cross-sectional view schematically showing the internal structure of the flying object 3 when viewed from the -Z side. The flying object 3 of the present embodiment is a drone including a main body portion 10, four propellers (11, 11, 11, 11), and two legs (12, 12) as shown in FIGS. 2A and 2B. Further, the main body portion 10 includes a photovoltaic module 20, a drive mechanism 30, and a camera 40.

[0044] Note that the flying object 3 is not limited to a drone as long as it is a flying object that flies by rotating a propeller by power or obtains a propulsive force and flies. For example, a hot air balloon equipped with a propeller is also assumed.

[0045] In the following description, the direction in which the light L1 is incident on the flying object 3 is defined as the Z direction, the direction in which the photovoltaic module 20 and the camera 40 are arranged, that is, the front-rear direction of the flying object 3 is defined as the Y direction, and the direction orthogonal to the Y direction and the Z direction, that is, the width direction of the flying object 3 is defined as the X direction. Note that the Z direction corresponds to the first direction.

[0046] In addition, in this specification, when expressing a direction, when distinguishing between positive and negative directions, it is described with positive and negative signs such as "+Z direction" and "-Z direction". When expressing a direction without distinguishing between positive and negative directions, it is simply described as "Z direction".

[0047] As shown in FIG. 2A, the main body 10 houses a photoelectric module 20 and a drive mechanism 30 inside, and an opening 10a for taking in light L1 from the outside is formed on the -Z side surface. Note that, as shown in FIG. 2B, a camera 40 for photographing the ground from above is mounted on the main body 10, but the camera 40 does not necessarily have to be mounted.

[0048] The propeller 11 is connected to the drive mechanism 30, and by controlling the rotation speed, the flying object 3 is made to float. Note that the flying object 3 in the present embodiment is provided with four propellers 11, but the number of propellers 11 can be arbitrary as long as it can fly without problems.

[0049] Also, the flying object 3 is provided only with the propellers 11 arranged to rotate on the XY plane. However, as long as it can fly without problems, the direction in which the propellers 11 are mounted can be arbitrary, and the directions of the plurality of mounted propellers 11 do not have to be the same.

[0050] The leg 12 is a member that supports the main body 10 when the flying object 3 lands. The shape and number of the legs 12 can be arbitrary, and even if there is a separate support member for supporting the flying object 3 during landing, the legs 12 do not necessarily have to be provided.

[0051] [Photoelectric Module 20] FIG. 3 is a schematic cross-sectional view of the photoelectric module 20 when viewed in the Y direction. FIG. 4A is a schematic view of the photoelectric module 20 when viewed from the -Z side, and FIG. 4B is a view showing the state where the optical component 23 is removed from FIG. 4A. FIG. 5A is a schematic view of one optical element 23a when viewed from the -Z side, and FIG. 5B is a schematic cross-sectional view of one optical element 23a and a corresponding one photoelectric conversion element 21 when viewed in the Y direction. In FIG. 5A, a part of the outer edge of the photoelectric conversion element 21 that can be seen through the transparent optical element 23a is shown by a broken line.

[0052] In FIG. 4B, the outer edge of the optical element 23a is virtually illustrated by a dotted line so as to easily understand the arrangement relationship between the photoelectric conversion element 21 and the optical element 23a. As shown in FIGS. 3 to 4B, the photovoltaic module 20 of the present embodiment includes a plurality of photoelectric conversion elements 21, an element substrate 22, optical components 23, and a plurality of holding members 24.

[0053] The photovoltaic module 20 is schematically shown in FIG. 2A and is electrically connected to the drive mechanism 30. When irradiated with the light L1, the photovoltaic module 20 is configured to supply the power generated in the photoelectric conversion element 21 to the drive mechanism 30.

[0054] The photoelectric conversion elements 21 of the present embodiment are arranged on the main surface on the +Z side of the element substrate 22 such that the light receiving surface 21a on which the photoelectric effect occurs by receiving the light L1 is parallel to the XY plane. Note that the outer edge of the photoelectric conversion element 21 in the present embodiment is 3.0 mm□ and the light receiving surface 21a is 2.2 mm□ when viewed from the Z direction.

[0055] The photoelectric conversion element 21 may be any element that generates the photoelectric effect by receiving light and can supply power to an object. The photoelectric conversion element 21 is, for example, a photodiode or a phototransistor (hereinafter, these may be collectively referred to as a "photo cell").

[0056] Note that the photoelectric conversion element 21 in this embodiment is an element composed of a GaN-based photodiode that exhibits relatively high sensitivity to light within the wavelength range of 375 nm to 450 nm. However, the photoelectric conversion element 21 is not limited to this. For example, an InGaP-based photocell exhibits relatively high sensitivity to light within the wavelength range of 500 nm to 630 nm, a GaAs-based photocell exhibits relatively high sensitivity to light within the wavelength range of 700 nm to 850 nm, an InGaAs-based photocell exhibits relatively high sensitivity to light within the wavelength range of 1,000 nm to 1,200 nm, and an InP-based photocell exhibits relatively high sensitivity to light within the wavelength range of 1,300 nm to 1,600 nm. That is, the wavelength of the light L1 emitted from the light source unit 2 can be appropriately selected according to the type of element employed in the photoelectric conversion element 21. Conversely, the type of the photoelectric conversion element 21 can be appropriately selected according to the light L1 emitted from the light source unit 2.

[0057] The element substrate 22 is a plate-shaped member on which the photoelectric conversion element 21 is placed on the main surface. The element substrate 22 in this embodiment is an aluminum nitride (AlN) substrate, but it may be, for example, a resin substrate, a glass substrate, a diamond substrate, or the like. Note that the element substrate 22 may be, for example, a substrate for crystal growth to form the photoelectric conversion element 21, which is a semiconductor element, and may be, for example, a sapphire substrate or a silicon carbide (SiC) substrate.

[0058] As shown in FIG. 4A, the optical component 23 has optical elements 23a whose outer edges exhibit a hexagonal shape closely arranged on the XY plane when viewed in the Z direction, and the whole is in a honeycomb shape. Then, as shown in FIG. 4B, the plurality of photoelectric conversion elements 21 are arranged at positions corresponding to each of the optical elements 23a on the -Z side main surface on the element substrate 22.

[0059] The optical component 23 of this embodiment has AR coating layers (23q1, 23q2) made of a dielectric multilayer film formed on the light incident surface 23p1 and the light exit surface 23p2 to suppress reflection of the incident light L1. The AR coating layers (23q1, 23q2) may be formed not only by a dielectric multilayer film but also, for example, by attaching a commercially available anti-reflection film, forming a dielectric multilayer film, forming a fine structure, or roughening the surface of the element substrate 22. Whether to form the AR coating layers (23q1, 23q2) on the light incident surface 23p1 and the light exit surface 23p2 of the optical component 23 is arbitrary.

[0060] Also, the thickness A1 of the thickest part of the optical element 23a (optical component 23) in the Z direction in this embodiment is 0.5 mm. For the reasons described above, the thickness A1 of the thickest part of the optical element 23a (optical component 23) in the Z direction is preferably 0.3 mm to 1.3 mm, and more preferably 0.4 mm to 1.2 mm. Note that the thickness of the optical element 23a (optical component 23) means the thickness of the part through which the light L1 passes, as described above, and does not include parts for simply fixing these elements.

[0061] As shown in FIGS. 4B and 5A, in the optical element 23a, when viewed in the Z direction, in the part of the incident surface 23p located outside the light receiving surface 21a of the photoelectric conversion element 21, a plurality of grooves 23d parallel to each side of the outer edge are formed in the radial direction, and a refractive part 23b is formed as a diffraction grating, which is a kind of diffractive optical element. And a light transmitting part 23c is formed in the region inside the refractive part 23b.

[0062] As shown in FIG. 5B, the refractive part 23b diffracts the incident light L1 on the light incident surface 23p1 into diffracted light L2, and makes a part of the diffracted light L2 travel toward the light receiving surface 21a of the photoelectric conversion element 21.

[0063] Since the light-transmitting portion 23c is a portion that allows the light L1 to pass through, from the viewpoint of further suppressing absorption by the optical element 23a, it may be a simple hole. Also, when viewed in the Z direction, the shape of the outer edge of the optical element 23a and the shape of the light-transmitting portion 23c are arbitrary. However, from the viewpoint of arranging without gaps, the shape of the outer edge of the optical element 23a preferably has a polygonal shape.

[0064] As the material constituting the optical element 23a, any material that is transparent to the light L1 may be used, for example, glass, resin, or the like. Also, the optical component 23 may be formed as an aggregate of optical elements 23a, or may be integrally formed by processing the surface shape of the optical component 23.

[0065] The holding member 24 is disposed between the element substrate 22 and the optical element 23a, and is a member for holding the element substrate 22 and the optical element 23a in a separated state. The length of the holding member 24 in the present embodiment, that is, the separation distance WD between the photoelectric conversion element 21 and the optical element 23a, is 2.8 mm.

[0066] When a structure for holding the element substrate 22 and the optical element 23a is formed inside the main body portion 10 of the flying object 3, the holding member 24 may not be provided. However, regarding the separation distance WD between the photoelectric conversion element 21 and the optical element 23a, a preferable range may be specified depending on the characteristics and shape of the optical element 23a. In such a case, it is preferable to provide the holding member 24 so that the separation distance WD can be maintained substantially constant with the photoelectric power generation module 20 alone.

[0067] Specifically, as described above, the separation distance WD between the photoelectric conversion element 21 and the optical element 23a is preferably 2.5 mm to 3.0 mm, and more preferably 2.6 mm to 2.9 mm. As the photoelectric power generation module 20, it is preferable to provide a holding member 24 whose length is adjusted so as to more surely keep the separation distance WD within this range.

[0068] [Drive mechanism 30] The drive mechanism 30 is electrically connected to the photovoltaic module 20, and in the photovoltaic module 20, the electric power generated by receiving the light L1 is supplied. Then, when the drive mechanism 30 is supplied with electric power from the photovoltaic module 20, it drives at a predetermined rotational speed of the propeller 11 according to the operation to be executed or the set operation mode.

[0069] The drive mechanism 30 is composed of, for example, an electric circuit that generates a drive electric signal and a motor that rotates the propeller 11 based on the generated electric signal. Note that the drive mechanism 30 may be provided with a control circuit such as a microcomputer or a CPU instead of or in addition to the electric circuit. Further, the drive mechanism 30 may be equipped with a memory in which information regarding the control mode is stored.

[0070] In the photovoltaic module 20 having the above configuration, when it proceeds as it is, a part of the light L1 that reaches the outside of the light-receiving surface 21a of the photoelectric conversion element 21 is refracted by the optical element 23a so as to proceed to the light-receiving surface 21a. That is, in the photovoltaic module 20 having the above configuration, since the amount of light incident on the light-receiving surface 21a of the photoelectric conversion element 21 increases, the power supply efficiency is improved as compared with the conventional configuration.

[0071] [Alternative Embodiment] Hereinafter, an alternative embodiment will be described.

[0072] 〈1〉 FIG. 6 is a schematic drawing when the photovoltaic module 20 in the alternative embodiment is viewed from the -Z side. FIG. 7A is a schematic drawing when one optical element 23a in the alternative embodiment is viewed from the -Z side, and FIG. 7B is a schematic drawing when one optical element 23a in the alternative embodiment and a corresponding one photoelectric conversion element 21 are viewed in the Y direction. The photovoltaic module 20 in the alternative embodiment includes an optical element 23a having a rectangular shape in the outer edge shape when viewed in the Z direction, as shown in FIGS. 6 and 7A.

[0073] Further, as shown in FIG. 7B, in another embodiment, the optical element 23a has a refractive portion 23b formed as a Fresnel lens, which is a type of diffractive optical element. Also, as shown in FIG. 7B, in the refractive portion 23b, a first region 23b1 and a second region 23b2 are formed, in which diffractive surfaces with different convergence points are formed. Therefore, in FIGS. 6 and 7A, instead of a groove, a boundary 23e with a changing inclination angle with respect to the XY plane of the incident surface is illustrated.

[0074] Here, as shown in FIG. 7B, the boundary 23e is formed on the light-emitting surface 23p2 on the +Z side of the optical element 23a. Therefore, the boundary 23e illustrated in FIG. 7A shows the shape as seen through the transparent optical element 23a. Along with this, in FIG. 7A, the outer edge (short dashed line) of the photoelectric conversion element 21 and the outer edge (short dashed line) of the light-receiving surface 21a of the photoelectric conversion element 21, as seen through the transparent optical element 23a, are illustrated.

[0075] Also, in the present embodiment, in order to prevent the light (L3, L4) refracted at the light-emitting surface 23p2 of the refractive portion 23b from being reflected away from the photoelectric conversion element 21 by the boundary 23e, the boundary 23e is preferably formed on the light-emitting surface 23p2.

[0076] Furthermore, a Fresnel lens generally has the characteristic of condensing light. Therefore, in order to achieve a uniform illuminance distribution on the light-receiving surface 21a of the photoelectric conversion element 21, it is preferable that the light (L3, L4) refracted in the refractive portion 23b and directed toward the photoelectric conversion element 21 is configured to be condensed toward the central portion side of the light-receiving surface 21a. For this reason, as shown in FIG. 7A, the optical element 23a of the present embodiment is formed in such a size that the outer edge of the light-transmitting portion 23c fits inside the outer edge of the light-receiving surface 21a of the photoelectric conversion element 21 when viewed in the Z direction.

[0077] The light L1 incident on the first region 23b1 travels as the first converging light L3 toward the light-receiving surface 21a of the photoelectric conversion element 21, as shown in FIG. 7B. The light L1 incident on the second region 23b2 travels as the second converging light L4 toward the light-receiving surface 21a of the photoelectric conversion element 21, as shown in FIG. 7B.

[0078] By forming the second region 23b2, when the entire refracting portion 23b was the first region 23b1, at least a part of the light that does not reach the light-receiving surface 21a of the photoelectric conversion element 21, such as the virtual light L5 shown as virtual light in FIG. 7B, will travel toward the photoelectric conversion element 21.

[0079] That is, with the above configuration, the power generation module 20 can improve the efficiency of power supply by light irradiation. Note that the relationship between the first region 23b1 and the second region 23b2 may be realized by adjusting the angles of refraction by the diffraction grating respectively.

[0080] In addition, even if the entire light incident surface 23p1 of the optical element 23a is configured as the first region 23b1, when power supply sufficient to maintain flight is possible, the second region 23b2 does not have to be formed on the light incident surface 23p1 of the optical element 23a.

[0081] 〈2〉 The configurations of the flying object 3 and the power generation module 20 described above are merely examples, and the present invention is not limited to the configurations shown in the drawings.

Description of Reference Numerals

[0082] 1: Photoelectric power supply system 2: Light source unit 3: Flying object 10: Main body portion 10a: Opening 11: Propeller 12: Leg portion 20: Power generation module 21: Photoelectric conversion element 21a: Light-receiving surface 22: Element substrate 23: Optical component 23a: Optical element 23b: Refractive part 23b1: First region 23b2: Second region 23c: Light-transmitting part 23d: Groove 23e: Boundary 23p1: Light incident surface 23p2: Light exit surface 23q1, 23q2: AR coating layer 24: Holding member 30: Driving mechanism 40: Camera L1: Light L2: Diffracted light L3: First converging light L4: Second converging light L5: Virtual light

Claims

1. A photoelectric conversion element having a light receiving surface and generating electricity when light is incident on the light receiving surface; a first direction perpendicular to the light receiving surface of the photoelectric conversion element, and an optical element having an incident surface located outside the light receiving surface, the optical element having a refractive portion that refracts at least a portion of the light incident on the incident surface so that it travels toward the light receiving surface.

2. 2. The photovoltaic module according to claim 1, wherein the refractive portion of the optical element is formed of a diffractive optical element.

3. 3. The photovoltaic module according to claim 2, wherein the refractive portion of the optical element is formed of a Fresnel lens.

4. The photovoltaic module according to claim 3, characterized in that the optical element has, in a radial direction centered on the optical axis of the Fresnel lens, a first region and a second region outside the first region, the second region including a diffractive surface having a different convergence point.

5. The photovoltaic module according to claim 2, characterized in that the refractive portion of the optical element has an outer edge having a polygonal shape when viewed in the first direction, and the diffractive optical element is a diffraction grating.

6. The photovoltaic module according to claim 5 , wherein the refractive portion of the optical element has an outer edge that is hexagonal when viewed in the first direction.

7. 2. The photovoltaic module according to claim 1, wherein the distance between the light receiving surface of the photoelectric conversion element and the optical element in the first direction is 2.5 mm to 3.0 mm.

8. The photovoltaic module according to claim 1, wherein the optical element has a thickness of 0.3 mm to 1.3 mm at its thickest portion in the first direction.

9. 2. The photovoltaic module according to claim 1, wherein the optical element has an AR coating layer formed on a light incident surface and a light exit surface.

10. The photovoltaic module according to claim 1, further comprising a holding member disposed between an element substrate having a plurality of the photoelectric conversion elements arranged on one main surface thereof and the optical element, the holding member holding the photoelectric conversion elements and the optical element in a spaced-apart state.

11. A photovoltaic module according to any one of claims 1 to 10; a drive mechanism connected to the photovoltaic module; and a propeller driven by the drive mechanism.

Images