Power device

The integration of a solar cell layer and a storage battery layer with a conductive substrate in the power device addresses the complexity and cost issues of existing technologies, achieving efficient energy utilization and simplified manufacturing.

WO2025094669A1PCT designated stage expired Publication Date: 2025-05-08PXP CORP +1
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Patent Information

Application Number
PCT/JP2024/036822
Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
Priority Date
2023-11-01
Filing Date
2024-10-16
Publication Date
2025-05-08

AI Technical Summary

Technical Problem

Existing power devices that integrate solar cells and storage batteries require complex wiring and control circuits, leading to increased costs and device size.

Method used

A power device design featuring a solar cell layer and a storage battery layer separated by a conductive substrate, eliminating the need for a control circuit by optimizing the voltage ratio between the solar cell and storage battery layers to between 0.58 and 0.84.

Benefits of technology

This design achieves high energy utilization efficiency and simplifies the device structure, eliminating the need for external control circuits and reducing manufacturing costs, while maintaining high power coupling efficiency.

✦ Generated by Eureka AI based on patent content.

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Abstract

Provided is a power device that has high energy utilization efficiency without requiring a control circuit for controlling power. Provided is a power device 100 comprising a solar cell layer PV that includes at least one solar cell, and a storage battery layer BT that is provided to the surface of the solar cell layer on the side opposite from a light-receiving surface of the solar cell layer and includes at least one storage battery, wherein an electroconductive substrate 201 serving as a common electrode between the solar cell layer PV and the storage battery layer BT is provided between the solar cell layer PV and the storage battery layer BT, and a voltage ratio, which is the ratio of the nominal voltage of the storage battery layer BT to the open voltage of the solar cell layer PV, is 0.58-0.84.
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Description

Power Devices

[0001] The present invention relates to power devices.

[0002] Solar cells are difficult to generate electricity due to bad weather or shadows, or during the night, so when they are used as a stable power source, they are used in conjunction with a power storage system. Patent Documents 1 to 3 describe technologies for integrating solar cells and storage batteries into a module.

[0003] U.S. Patent No. 8,704,078 U.S. Patent No. 4,481,265 U.S. Patent No. 4,740,431

[0004] The technology described in Patent Document 1 requires complicated wiring and a large number of components when connecting a solar cell and a storage battery, resulting in increased costs. Patent Document 2 describes a technology in which a storage battery is stacked on the same substrate as a solar cell, but the substrate still requires through-holes for wiring and a circuit for controlling power, resulting in a complex structure. Patent Document 3 describes a structure in which a solar cell and a storage battery share a common electrode on a conductive substrate. However, the device described in Patent Document 3 also simply integrates a solar cell and a storage battery, necessitating the installation of a separate external circuit for controlling power, resulting in a large device size.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a power device that does not require a control circuit for controlling power and has high energy utilization efficiency.

[0006] An electric power device according to one embodiment of the present disclosure is an electric power device including a solar cell layer including at least one solar cell, and a storage battery layer including at least one storage battery, the storage battery layer being provided on the surface opposite to the light-receiving surface of the solar cell layer, wherein a conductive substrate is provided between the solar cell layer and the storage battery layer to serve as a common electrode for the solar cell layer and the storage battery layer, and the voltage ratio, which is the ratio of the nominal voltage of the storage battery layer to the open-circuit voltage of the solar cell layer, is 0.58 to 0.84.

[0007] According to the present invention, it is possible to provide a power device that does not require a control circuit for controlling power and has high energy utilization efficiency.

[0008] 1 is a cross-sectional view of a power device according to the present embodiment; FIG. 2 is a cross-sectional view of another power device according to the present embodiment; FIG. 3 is a cross-sectional view of another power device according to the present embodiment; FIG. 4 is a cross-sectional view of another power device according to the present embodiment; FIG. 5 is a cross-sectional view of another power device according to the present embodiment; FIG. 6 is a diagram showing power coupling efficiency as a function of a state of charge and a voltage coupling ratio of a storage battery under standard test conditions for a solar cell; FIG. 7 is a diagram showing power coupling efficiency as a function of a state of charge and a voltage coupling ratio of a storage battery based on real environment data; FIG. 8 is a diagram showing power coupling efficiency as a function of a state of charge and a voltage coupling ratio of a storage battery based on real environment data; FIG. 9 is a diagram showing power coupling efficiency as a function of a state of charge and a voltage coupling ratio of a storage battery based on real environment data; FIG. 10 is a diagram showing power coupling efficiency as a function of a state of charge and a voltage coupling ratio of a storage battery based on real environment data; FIG. 10 shows the average charging current density of the battery as a function of the solar irradiance ratio and the voltage coupling ratio under standard test conditions for the solar cell excluding the solar irradiance.

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described with reference to the accompanying drawings. In the drawings, components with the same reference numerals have the same or similar configurations.

[0010] 1 shows a cross-sectional view of a power device 100 according to this embodiment. The power device 100 has a solar cell layer PV, a conductive substrate 201, and a storage battery layer BT. The solar cell layer PV has a solar cell 101 and a solar cell 102. The storage battery layer BT has a storage battery 301, which is provided on the surface opposite to the light-receiving surface of the solar cell layer.

[0011] In the electric power device 100, the solar cells 101 and 102 receive light from the electrode 103 side and generate electricity. The storage battery 301 is charged with the generated electricity. When the solar cells 101 and 102 are not generating electricity, for example, due to bad weather, shadow, or nighttime, the electric power device 100 supplies power from the storage battery 301 to an external load.

[0012] The solar cell 101 is a perovskite solar cell having a transparent conductive film 1011, an electron transport layer 1012, a perovskite light absorbing layer 1013, and a hole transport layer 1014. The electron transport layer 1012 is a layer formed of an n-type semiconductor. The perovskite light absorbing layer 1013 is a light absorbing layer formed of a semiconductor having a perovskite structure, and various materials can be used as the material, including materials having a perovskite structure such as (Cs,FA)PbI3. The hole transport layer 1014 is a layer formed of a p-type semiconductor. In this embodiment, the band gap of the solar cell 101 is approximately 1.55 eV.

[0013] The solar cell 102 is a chalcopyrite solar cell having a transparent conductive film 1021, an electron transport layer 1022, a chalcopyrite light absorption layer 1023, and a hole transport layer 1024. The electron transport layer 1022 is a layer formed of an n-type semiconductor, and the chalcopyrite light absorption layer 1023 is a light absorption layer having a chalcopyrite structure, and various materials can be used as materials, including materials having a chalcopyrite structure such as Cu(In,Ga)(Se,S)2. The hole transport layer 1024 is a layer formed of a p-type semiconductor. In this embodiment, the band gap of the solar cell 102 is approximately 1.01 eV.

[0014] Since the solar cell 101 and the solar cell 102 use different wavelengths of light for power generation, more efficient power generation is possible by connecting the solar cell 101 and the solar cell 102 in series.

[0015] The electrode 103 is, for example, an electrode disposed on the solar cell 101 to extract electricity from the solar cell 101. The electrode 103 is a negative electrode. The electrode 103 is made of a conductive material, and for example, a metal material, an alloy material, or a transparent conductive material can be used. The solar cell 101 and the solar cell 102 are connected in series via a transparent conductive film 1021, and electricity generated in the solar cell 102 is extracted from the electrode 103 via the solar cell 101.

[0016] The conductive substrate 201 is provided between the solar cell 102 and the storage battery 301 and functions as a common electrode for the solar cell 102 and the storage battery 301. The conductive substrate 201 is a positive electrode. The conductive substrate 201 is, for example, a metal foil. Alternatively, the conductive substrate 201 may be a member formed by depositing a metal material on a substrate. The conductive substrate 201 may also be a member formed by bonding multiple conductive substrates (or metal foils, etc.). The solar cell layer PV and the storage battery layer BT may use a portion of the conductive substrate 201 as a common electrode, and the solar cell layer PV and the storage battery layer BT may have different areas. The solar cell 102 and the solar cell 101 are connected in series via a transparent conductive film 1021, and electricity generated by the solar cell 101 is extracted from the conductive substrate 201 via the solar cell 102.

[0017] The storage battery 301 is provided on the surface opposite to the light-receiving surface of the solar cells 101, 102. The storage battery 301 has a positive electrode layer (positive electrode composite layer) 3011 connected to the conductive substrate 201, an electrolyte layer 3012, a negative electrode layer (negative electrode composite layer) 3013, and an electrode 302. The storage battery 301 is, for example, an all-solid-state magnesium ion battery or an all-solid-state sodium ion battery. The electrode 302 is a negative electrode. The storage battery 301 shares a positive electrode with the solar cells 101, 102 and is connected to the electrode 103 through the electrode 302. In the power device 100, one storage battery 301 is used in the storage battery layer BT, but the storage battery layer BT may be composed of multiple storage batteries.

[0018] In the power device 100, the solar cell layer PV may include silicon solar cells, chalcopyrite solar cells, kesterite solar cells, cadmium telluride solar cells, or perovskite solar cells, or a combination of these cells.

[0019] Furthermore, in the solar cell layer PV, multiple solar cells may be connected in series. A power device 100A in which multiple solar cells are connected in series is shown in FIG. 2 . In the power device 100A, the solar cell layer PV includes solar cells 101, 101A, and 101B. The solar cells 101A and 101B are perovskite solar cells each including a transparent conductive film 1011A or 1011B, an electron transport layer 1012A or 1012B, a perovskite light absorption layer 1013A or 1013B, and a hole transport layer 1014A or 1014B. The solar cells 101A and 101B are each provided with an electrode 103A or 103B and a conductive base 201A or 201B. The solar cell 101A is connected in series with the solar cell 101 through the electrode 103A and the conductive base 201A. Solar cell 101B is connected in series with solar cell 101 and solar cell 101A through electrode 103A and conductive base 201B. Conductive base 201 is insulated from conductive bases 201A and 201B by insulator 401. Furthermore, solar cell layer PV may have a structure in which solar cells 101 and 102 are stacked as one set, and a plurality of sets are connected in series, as shown in FIG.

[0020] In the power device 100 and the power device 100A, the open-circuit voltage of the solar cell layer PV is the sum of the open-circuit voltages of the multiple solar cells. Here, the open-circuit voltage is the voltage across the positive and negative terminals of the solar cell when they are open-circuited under standard solar cell test conditions.

[0021] In the electric power device 100 and the electric power device 100A, the storage battery layer BT may include a storage battery such as an all-solid-state battery, a semi-solid-state battery, or a combination thereof. The all-solid-state battery or the semi-solid-state battery may include a proton battery, a lithium ion battery, a sodium ion battery, a potassium ion battery, a magnesium ion battery, a copper ion battery, or a silver ion battery, or a combination thereof.

[0022] In the storage battery layer BT, multiple storage batteries may be connected in series, as in the power device 100B shown in FIG. 3 . In the power device 100B, the storage battery layer BT includes a storage battery 301 and a storage battery 303. The storage battery 303 includes a positive electrode layer (positive electrode composite layer) 3031 connected to an electrode 302, an electrolyte layer 3032, a negative electrode layer (negative electrode composite layer) 3033, and an electrode 304. The electrode 304 is a negative electrode. In this case, the nominal voltage of the storage battery layer BT is the sum of the nominal voltages of the multiple storage batteries. Here, the nominal voltage refers to the average operating voltage when discharged under typical conditions, which refer to conditions of discharging from a fully charged state to a discharge termination state at 25°C and a discharge rate of 1C.

[0023] In addition, in the storage battery layer BT, multiple storage batteries may be connected in parallel, as in the power device 100C shown in FIG. 4 . In the power device 100C, the storage battery layer BT includes a storage battery 301 and a storage battery 303. The storage battery 303 includes a negative electrode layer (negative electrode composite layer) 3033 connected to the electrode 302, an electrolyte layer 3032, a positive electrode layer (positive electrode composite layer) 3031, and an electrode 304. The electrode 304 is a positive electrode. In this case, the nominal voltage of the storage battery layer BT is the average value of the nominal voltages of the multiple storage batteries.

[0024] In the power device 100, the open-circuit voltage of the solar cell layer PV can be set by changing the type and connection of the solar cells used in the solar cell layer PV. Furthermore, in the power device 100, the nominal voltage of the storage battery layer BT can be set by changing the type and connection of the storage battery used in the storage battery layer BT. More specifically, the open-circuit voltage can be increased by changing the light absorption layer material of the solar cell to a material with a wider band gap. For example, the band gap can be widened by using a material in which iodine is partially substituted with bromine in perovskite solar cells, or by using a material in which indium is partially substituted with gallium and a material in which selenium is partially substituted with sulfur in chalcopyrite solar cells. Furthermore, the open-circuit voltage can be increased by increasing the number of solar cells connected in series. Furthermore, the nominal voltage can be lowered by changing the type of storage battery from a sodium-ion battery or magnesium-ion battery to a proton battery, copper-ion battery, or silver-ion battery, and the nominal voltage can be increased by changing to a lithium-ion battery or potassium-ion battery. Furthermore, in each storage battery, the nominal voltage can be increased by using an oxide material for the positive electrode material, and decreased by using a sulfide material. The nominal voltage can be increased by using a metal element or carbon for the negative electrode material, and decreased by using an oxide or sulfide material. The nominal voltage can also be increased by increasing the number of storage batteries connected in series.

[0025] The following describes the relationship between the open-circuit voltage of the solar cell layer PV composed of the solar cells 101 and 102 and the nominal voltage of the storage battery layer BT. In the power device 100, the voltage ratio (voltage coupling ratio) between the open-circuit voltage of the solar cell layer PV and the nominal voltage of the storage battery layer (storage battery 301) is set to a value between 0.58 and 0.84.

[0026] In the power device 100, the open-circuit voltage of the solar cell layer PV formed by the solar cells 101 and 102 is approximately 1.81 V. Furthermore, when the storage battery 301 is an all-solid-state magnesium ion battery, the nominal voltage of the storage battery layer BT is approximately 1.15 V. In this case, the voltage coupling ratio is 0.64. When the storage battery 301 is an all-solid-state sodium ion battery, the nominal voltage of the storage battery layer BT is approximately 1.48 V. In this case, the voltage coupling ratio is 0.82. In this way, in the power device 100, the voltage coupling ratio can be set by setting the open-circuit voltage of the solar cell layer PV and the nominal voltage of the storage battery layer BT.

[0027] The solar cells and storage batteries used in the solar cell layer PV and the storage battery layer BT can be combined in a manner different from the example shown in Figure 1. For example, when a lithium ion battery or a potassium ion battery with a relatively high nominal voltage is used in the storage battery layer BT, the solar cell layer PV can be configured by connecting three solar cells, each with solar cells 101 and 102 connected in tandem, in series, and the storage battery layer BT can be configured by a single lithium ion battery or potassium ion battery, thereby appropriately adjusting the voltage coupling ratio. Furthermore, when a proton battery, copper ion battery, or silver ion battery with a relatively low nominal voltage is used in the storage battery layer, the solar cell layer PV can be configured by providing one solar cell with solar cells 101 and 102 connected in tandem, and the storage battery layer BT can be configured by connecting two or three storage batteries in series, thereby appropriately adjusting the voltage coupling ratio.

[0028] Example 1 Example 1 will be described with reference to Figures 5, 6A, 6B, 6C, and 6D. Figure 5 shows the results of a numerical simulation of the voltage coupling ratio of the power device 100 and the power coupling efficiency relative to the state of charge of the storage battery layer BT under standard test conditions (STC) for solar cells. The standard test conditions are an air mass (AM) of 1.5, a temperature of 25°C, and a solar radiation intensity of 1 kW / m. 2The power coupling efficiency is defined as the ratio of the power supplied to the storage battery and the external load to the power generated at the optimum operating point of the solar cell.

[0029] The results shown in FIG. 5 are obtained under standard test conditions for solar cells when no external load is connected to the power device 100 and all of the power generated by the solar cell layer PV is supplied to the storage battery layer BT.

[0030] As shown in Fig. 5, when the voltage coupling ratio is between 0.58 and 0.84, the power coupling efficiency is generally 80% or more in various states of charge. Note that the voltage coupling ratio at which the power coupling efficiency is generally 80% or more may be determined to be between 0.58 and 0.82 by averaging the voltage coupling ratios shown in Fig. 6.

[0031] Furthermore, when the voltage coupling ratio is 0.63 to 0.79, the power coupling efficiency is generally 90% or higher. For example, when the voltage coupling ratio is 0.63, the average power coupling efficiency in each state of charge is 90%, and when the voltage coupling ratio is 0.79, the average power coupling efficiency in each state of charge is 91%.

[0032] Furthermore, when the voltage coupling ratio is 0.68 to 0.74, the power coupling efficiency is generally 95% or higher. For example, when the voltage coupling ratio is 0.68, the average power coupling efficiency at each state of charge is 95%, and when the voltage coupling ratio is 0.74, the average power coupling efficiency at each state of charge is 97%.

[0033] Figures 6A to 6D show numerical simulation results of the voltage coupling ratio of the power device 100 and the power coupling efficiency versus the state of charge of the battery layer BT, using a module installed horizontally on the ground in Tokyo and actual measurements of AM, temperature, and solar radiation intensity for each season of the year (spring, summer, fall, and winter). In Figures 6A to 6D, the power coupling efficiency is calculated using the integrated value from sunrise to sunset. As a year-round trend, the voltage coupling ratio, at which the power coupling efficiency increases, tends to shift to values ​​higher than those in spring and summer as the solar elevation and temperature decrease. In Figures 6A to 6D, when the voltage coupling ratio is between 0.58 and 0.84, the power coupling efficiency is generally 80% or higher at various states of charge. Furthermore, when the voltage coupling ratio is between 0.68 and 0.79, the power coupling efficiency is generally 90% or higher. Furthermore, when the voltage coupling ratio is around 0.74, the power coupling efficiency is generally 95% or more.

[0034] A high power coupling efficiency means that more power generated by the solar cell layer PV is supplied to the storage battery layer BT. In this way, by appropriately adjusting the voltage coupling ratio, it is possible to efficiently charge the storage batteries in the storage battery layer BT without providing a separate control circuit.

[0035] Example 2 Example 2 will be described with reference to Figures 7, 8A, 8B, 8C, and 8D. Figure 7 shows the results of a numerical simulation of the power coupling efficiency as a function of the voltage coupling ratio of the power device 100 and the resistance value of the load connected to the power device 100 under standard solar cell test conditions. In Figure 7 and the following Figures 8A, 8B, 8C, and 8D, the power coupling efficiency is calculated as an average value when the state of charge is changed from 5 to 95%. The numerical value corresponding to the case without load in Figure 7 corresponds to the average value shown in the bottom row of Figure 6.

[0036] As shown in Fig. 7, when the voltage coupling ratio is between 0.63 and 0.89, the power coupling efficiency is generally 80% or more in various states of charge. Note that the voltage coupling ratio at which the power coupling efficiency is generally 80% or more may be determined to be between 0.60 and 0.87 by averaging the voltage coupling ratios shown in Fig. 7.

[0037] Furthermore, when the voltage coupling ratio is between 0.74 and 0.84, the power coupling efficiency is generally 90% or higher. For example, when the voltage coupling ratio is 0.74, the average power coupling efficiency is 92%, and when the voltage coupling ratio is 0.84, the average power coupling efficiency is 91%.

[0038] Furthermore, when the voltage coupling ratio is around 0.79, the power coupling efficiency is 95% or more. When the voltage coupling ratio is 0.79, the average value of the power coupling efficiency is 95%.

[0039] 8A to 8D show numerical simulation results of the voltage coupling ratio of the power device 100 and the power coupling efficiency versus the resistance value of the load connected to the power device 100, respectively, using a module installed horizontally on the ground in Tokyo and actual measured values ​​of AM, temperature, and solar radiation intensity for each season of the year (spring, summer, autumn, and winter). In FIGS. 8A to 8D, the power coupling efficiency is calculated using an integrated value from sunrise to sunset. As a trend throughout the year, similar to the examples shown in FIGS. 6A to 6D, the voltage coupling ratio, at which the power coupling efficiency increases, tends to shift to values ​​higher than those in spring and summer in autumn and winter, when the solar altitude and temperature decrease.

[0040] 8A to 8C, when the voltage coupling ratio is between 0.60 and 0.87, the power coupling efficiency is approximately 80% or higher. When the voltage coupling ratio is between 0.72 and 0.82, the power coupling efficiency is approximately 90% or higher. When the voltage coupling ratio is around 0.79, the power coupling efficiency is approximately 95% or higher.

[0041] Considering the winter conditions shown in Figure 8D, when the voltage coupling ratio is between 0.63 and 0.89, the power coupling efficiency is approximately 80% or higher. Furthermore, when the voltage coupling ratio is between 0.79 and 0.84, the power coupling efficiency is approximately 90% or higher. Furthermore, when the voltage coupling ratio is around 0.84, the power coupling efficiency is approximately 95% or higher. Also, Figures 7, 8A, 8B, 8C, and 8D show that the power coupling efficiency increases when the load resistance is high.

[0042] In this way, even when a load is connected, by appropriately adjusting the voltage coupling ratio, it is possible to efficiently charge the storage batteries in the storage battery layer BT without providing a separate control circuit.

[0043] Example 3 will be described with reference to Fig. 9. Fig. 9 shows simulation results of the average current density of the current flowing from the solar cell layer PV to the storage battery layer BT with respect to the voltage coupling ratio and the solar irradiance ratio of the power device 100 under standard test conditions for the solar cell excluding the solar irradiance. The solar irradiance ratio is the ratio of the actual solar irradiance to the solar irradiance under the standard test conditions.

[0044] In the power device 100, when the solar cell layer PV receives a sufficient amount of light and generates power, current flows from the solar cell layer PV to the storage battery layer BT, charging the storage battery in the storage battery layer BT. As shown in FIG. 9 , when the solar irradiance ratio changes from 1.000 to 0.010, some of the average current density values ​​become negative. This indicates that current flows from the storage battery layer BT to the solar cell layer PV, i.e., a reverse current occurs. The occurrence of a reverse current when the solar irradiance decreases means that the power charged in the storage battery in the storage battery layer BT during the day is naturally consumed at night.

[0045] As shown in FIG. 9 , when the voltage coupling ratio is between 0.58 and 0.84, the reverse current can be suppressed to a few percent of the current during power generation. More specifically, by setting the voltage coupling ratio between 0.58 and 0.82, the reverse current can be suppressed to approximately 1% of the current during power generation. Therefore, even if a reverse current occurs at night, the storage battery can be kept fully charged and power can be maintained. While a backflow prevention diode can be considered to prevent reverse current, the power device 100 does not require a backflow prevention diode by setting the voltage coupling ratio to 0.58 to 0.84. This allows the power device 100 to be manufactured with a simple structure and at low cost.

[0046] <Summary> Based on the results shown in Examples 1, 2, and 3, by setting the voltage coupling ratio between the solar cell layer PV and the storage battery layer BT between 0.60 and 0.82, the power device 100 does not require an external charge / discharge control circuit or a reverse current prevention diode. This allows the power device 100 to be manufactured with a simple structure and low cost, and further enables high power coupling efficiency. The power device 100 can automatically supply power from the storage battery layer BT when the solar cell layer PV is unable to generate power. Therefore, by installing the power device 100 on the roof, window, wall, or other surface of a building, a mobile object such as a vehicle, or an aircraft that is particularly susceptible to shadows, solar energy can be utilized while maintaining a simple structure. Alternatively, the power device 100 can be used as an independent power source for street lights or display devices. The power device 100 can also be used as a power source for mobile devices and devices in space or the stratosphere.

[0047] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The elements of the embodiments, as well as their arrangement, materials, conditions, shapes, sizes, etc., are not limited to those illustrated and can be modified as appropriate. Furthermore, configurations shown in different embodiments can be partially substituted or combined with each other.

[0048] 100, 100A, 100B, 100C...power device, 101,102...solar cell, 103...electrode, 201...conductive substrate, 301...storage battery, PV...solar cell layer, BT...storage battery layer

Claims

1. A power device comprising a solar cell layer including at least one solar cell, and a storage battery layer including at least one storage battery provided on the surface of the solar cell layer opposite the light-receiving surface, wherein a conductive substrate is provided between the solar cell layer and the storage battery layer to serve as a common electrode for the solar cell layer and the storage battery layer, and a voltage ratio, which is the ratio of the open circuit voltage of the solar cell layer to the nominal voltage of the storage battery layer, is 0.58 to 0.

84.

2. A power device according to claim 1, wherein said voltage ratio is between 0.60 and 0.

82.

3. A power device according to claim 1, wherein when a load is connected to said power device, said voltage ratio is between 0.63 and 0.

82.

4. A power device according to claim 1, wherein when a load is connected to said power device, said voltage ratio is between 0.74 and 0.

82.

5. A power device according to claim 1, wherein the solar cell layer has a plurality of solar cells connected in series, and the open circuit voltage of the solar cell layer is the sum of the open circuit voltages of the plurality of solar cells.

6. The power device of claim 1, wherein the at least one solar cell comprises a silicon solar cell, a chalcopyrite solar cell, a kesterite solar cell, a cadmium telluride solar cell, or a perovskite solar cell, or a combination thereof.

7. A power device according to claim 1, wherein the battery layer has a plurality of batteries connected in series, and the nominal voltage of the battery layer is the sum of the nominal voltages of each of the plurality of batteries.

8. The power device according to claim 1, wherein the battery layer has a plurality of batteries connected in parallel, and the nominal voltage of the battery layer is an average value of the nominal voltages of each of the plurality of batteries.

9. The power device according to claim 1, wherein the at least one storage battery comprises a solid-state battery or a semi-solid-state battery, or a combination thereof.

10. The power device according to claim 9, wherein the all-solid-state battery or the semi-solid-state battery comprises a proton battery, a lithium ion battery, a sodium ion battery, a potassium ion battery, a magnesium ion battery, a copper ion battery, or a silver ion battery, or a combination thereof.

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