Photovoltaic power system

Abstract

This system provides a photovoltaic power system that suppresses malfunctions caused by self-consumption. [Solution] The photovoltaic system 1 is generally configured to include a photovoltaic element 2 that converts incident light energy into electrical energy and outputs power P1, a rechargeable battery 3 that is charged using the power P1 generated by the photovoltaic element 2, a grounding circuit 4 that grounds the photovoltaic element 2, a switching unit 5 that switches the electrical connection between the photovoltaic element 2 and the rechargeable battery 3, and the electrical connection between the photovoltaic element 2 and the grounding circuit 4, and a control unit 7 that controls the switching unit 5 to switch the electrical connection with the photovoltaic element 2 from the rechargeable battery 3 to the grounding circuit 4 when a stop condition for stopping the charging of the rechargeable battery 3 is met.

Description

Technical Field

[0001] The present invention relates to a photovoltaic power generation system.

Background Art

[0002] As a conventional technology, an independent power supply device is known, which includes a solar cell disposed on the outer top surface or side surface of a container, and a power storage device that stores electricity obtained from the solar cell and supplies the stored electricity to an external load such as a lighting device (for example, see Patent Document 1).

[0003] When the standby mode is selected or maintained, this independent power supply device stops discharging to the external load. Further, when the voltage of the power storage device becomes smaller than a predetermined lower limit voltage, charging from the solar cell to the power storage device is started, and when the voltage of the power storage device becomes equal to or higher than a predetermined upper limit voltage, charging from the solar cell to the power storage device is stopped.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] A solar cell inevitably has an internal resistance. As long as light is incident, the solar cell continues to generate electricity even if no load is connected, so power self-consumption due to the internal resistance occurs. Therefore, in the standby mode, when the conventional independent power supply device stops discharging to the external load and stops charging the storage battery, heat is generated due to self-consumption, and problems such as deterioration, failure, and fire occurrence of the solar cell may occur.

[0006] Therefore, an object of the present invention is to provide a photovoltaic power generation system that suppresses problems due to self-consumption. [Means for solving the problem]

[0007] One aspect of the present invention provides a photovoltaic system comprising: a photovoltaic element that converts incident light energy into electrical energy and outputs power; a rechargeable battery that is charged using the power generated by the photovoltaic element; a grounding circuit that grounds the photovoltaic element; a switching unit that switches the electrical connection between the photovoltaic element and the rechargeable battery, and the electrical connection between the photovoltaic element and the grounding circuit; and a control unit that controls the switching unit to switch the electrical connection between the photovoltaic element from the rechargeable battery to the grounding circuit when a stop condition for stopping the charging of the rechargeable battery is met. [Effects of the Invention]

[0008] According to the present invention, malfunctions caused by self-consumption can be suppressed. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a block diagram showing an example of the first circuit of a photovoltaic system according to an embodiment. [Figure 2] Figure 2 is a block diagram showing an example of a second circuit in the photovoltaic system according to the embodiment. [Figure 3] Figure 3 is a flowchart showing an example of the operation of a photovoltaic system according to an embodiment. [Modes for carrying out the invention]

[0010] (Summary of the embodiment) The photovoltaic system according to this embodiment is generally configured to include: a photovoltaic element that converts incident light energy into electrical energy and outputs power; a rechargeable battery that is charged using the power generated by the photovoltaic element; a grounding circuit that grounds the photovoltaic element; a switching unit that switches the electrical connection between the photovoltaic element and the rechargeable battery, and the electrical connection between the photovoltaic element and the grounding circuit; and a control unit that controls the switching unit to switch the electrical connection with the photovoltaic element from the rechargeable battery to the grounding circuit when a stop condition for stopping the charging of the rechargeable battery is met.

[0011] This photovoltaic system, when charging of the rechargeable battery is stopped, connects the photovoltaic element to a grounding circuit to consume the generated power, thereby suppressing malfunctions due to self-consumption compared to systems that do not employ this configuration.

[0012] [Embodiment] (Overview of Photovoltaic System 1) Figure 1 is a block diagram showing an example of the first circuit of the photovoltaic system according to the embodiment. Figure 2 is a block diagram showing an example of the second circuit of the photovoltaic system according to the embodiment. In Figures 1 and 2, the main signals and power flows are indicated by arrows.

[0013] As shown in Figures 1 and 2, the photovoltaic system 1 is generally configured to include a photovoltaic element 2 that converts incident light energy into electrical energy and outputs power P1, a rechargeable battery 3 that is charged using the power P1 generated by the photovoltaic element 2, a grounding circuit 4 that grounds the photovoltaic element 2, a switching unit 5 that switches the electrical connection between the photovoltaic element 2 and the rechargeable battery 3, and the electrical connection between the photovoltaic element 2 and the grounding circuit 4, and a control unit 7 that controls the switching unit 5 to switch the electrical connection with the photovoltaic element 2 from the rechargeable battery 3 to the grounding circuit 4 when a stop condition for stopping the charging of the rechargeable battery 3 is met.

[0014] The control unit 7 is configured to use the condition that the rechargeable battery 3 is charged to a predetermined capacity as a stop condition, and when this stop condition is satisfied, control the switching unit 5 to electrically connect the photovoltaic element 2 and the grounding circuit 4.

[0015] Further, the control unit 7 is configured to use the condition that an abnormality has occurred in the charging of the rechargeable battery 3 as a stop condition, and when any one of these stop conditions is satisfied, control the switching unit 5 to electrically connect the photovoltaic element 2 and the grounding circuit 4.

[0016] That is, the control unit 7 is configured to control the switching unit 5 to electrically connect the photovoltaic element 2 and the grounding circuit 4 when either one of the conditions that the rechargeable battery 3 is charged to a predetermined capacity and that an abnormality has occurred in the charging of the rechargeable battery 3 is satisfied.

[0017] As a modification, when the rechargeable battery 3 is configured to be removable, the control unit 7 is configured to use the condition that the rechargeable battery 3 has been removed as a stop condition, and when any one of these stop conditions is satisfied, control the switching unit 5 to electrically connect the photovoltaic element 2 and the grounding circuit 4. Therefore, in this modification, the control unit 7 is configured to control the switching unit 5 to electrically connect the photovoltaic element 2 and the grounding circuit 4 when either one of the conditions that the rechargeable battery 3 is charged to a predetermined capacity, that an abnormality has occurred in the charging of the rechargeable battery 3, and that the rechargeable battery 3 has been removed is satisfied.

[0018] When charging the rechargeable battery 3, the photovoltaic power generation system 1 forms a first electric circuit R1 as shown in FIG. 1. When not charging the rechargeable battery 3, the photovoltaic power generation system 1 forms a second electric circuit R2 as shown in FIG. 2.

[0019] As shown in FIGS. 1 and 2, the photovoltaic power generation system 1 drives the load 8 by the power P3 of the rechargeable battery 3 in any case of the first electric circuit R1 and the second electric circuit R2, but is not limited thereto.

[0020] (Configuration of the Photovoltaic Element 2) The photovoltaic element 2 is schematically configured to include a plurality of cells that convert the light energy of light 9, such as sunlight, into electrical energy. The photovoltaic system 1 may be configured to include a plurality of photovoltaic elements 2.

[0021] For the photovoltaic element 2, for example, an organic solar cell, a silicon solar cell, a compound solar cell, an organic-inorganic hybrid solar cell, or the like can be used.

[0022] The photovoltaic element 2 of the present embodiment is, as an example, a perovskite solar cell. The perovskite solar cell is an organic-inorganic hybrid solar cell, is manufactured from a material having a perovskite structure, and is lightweight and excellent in flexibility.

[0023] (Configuration of the rechargeable battery 3) The rechargeable battery 3 is, for example, a lead-acid battery, a nickel-metal hydride battery, a lithium-ion battery, a NAS battery, or the like. The rechargeable battery 3 of the present embodiment is, as an example, a lithium-ion battery. The photovoltaic system 1 may, for example, include a plurality of rechargeable batteries 3, or the rechargeable battery 3 may be removable.

[0024] As shown in FIG. 1, the rechargeable battery 3 is connected to the control unit 7. The rechargeable battery 3 is charged by the power P2 input via the control unit 7. In the case where the photovoltaic system 1 does not have a function for the control unit 7 to control charging, the photovoltaic system 1 may be configured to include a charging circuit for controlling charging between the rechargeable battery 3 and the control unit 7.

[0025] (Configuration of the grounding circuit 4) The grounding circuit 4 is a circuit that causes the power P1 generated by the photovoltaic element 2 to flow to the ground (earth) and be consumed. That is, when the charging of the rechargeable battery 3 is stopped, the photovoltaic system 1 does not self-consume the power P1 generated by the photovoltaic element 2, but causes it to flow to the ground (earth) and be consumed by the grounding circuit 4.

[0026] As a variation, if the photovoltaic system 1 is mounted on an aircraft or vehicle, the grounding circuit 4 may be configured using a so-called chassis ground, such as the aircraft fuselage or vehicle body, as the ground (GND). The grounding circuit 4 may also be configured to adjust the power value flowing to the aircraft fuselage or vehicle body using resistors or the like.

[0027] (Configuration of switching unit 5) As shown in Figures 1 and 2, the switching unit 5 is positioned between the photovoltaic element 2 and the control unit 7. The switching unit 5 is configured to include, for example, a MOSFET (metal-oxide-semiconductor field-effect transistor). The switching unit 5 switches the circuit for the power P1 generated by the photovoltaic element 2 based on the control signal S output from the control unit 7. In Figures 1 and 2, solid lines indicate electrically connected circuits, and dotted lines indicate electrically unconnected circuits.

[0028] (Configuration of memory unit 6) The memory unit 6 is, for example, a semiconductor memory, but it may be any other memory device. This memory unit 6 stores a threshold value 60. This threshold value 60 is a voltage value that indicates a predetermined capacity. For example, if the voltage of the rechargeable battery 3 when fully charged is aV and the predetermined capacity is b%, then the threshold value 60 is given by a × b / 100 (V). For example, if the rechargeable battery 3 can be charged to 98%, then the threshold value 60 will be a × 0.98 (V). The threshold value 60 may also be determined by converting the voltage of the rechargeable battery 3 to its capacity. As a variation, the threshold value 60 may be configured to change according to the rechargeable capacity of the rechargeable battery 3.

[0029] (Configuration of the control unit 7) The control unit 7 is a microcomputer composed of, for example, a CPU (Central Processing Unit) that performs calculations and processing on acquired data according to a stored program, and semiconductor memory such as RAM (Random Access Memory) and ROM (Read Only Memory). The ROM stores, for example, the program necessary for the control unit 7 to operate. The RAM is used, for example, as a storage area to temporarily store calculation results.

[0030] As shown in Figure 1, the control unit 7 is electrically connected to the rechargeable battery 3. The control unit 7 is configured to control the charging of the rechargeable battery 3. In a modified configuration, if the rechargeable battery 3 is removable, the control unit 7 has a function to detect whether the rechargeable battery 3 is connected or disconnected.

[0031] The control unit 7 converts the power P1 generated by the photovoltaic element 2 into power P2 suitable for charging and charges the rechargeable battery 3. The control unit 7 is also configured to detect charging abnormalities. If a charging abnormality is detected, the control unit 7 switches the circuit from the first circuit R1 to the second circuit R2. This detection of charging abnormalities includes, for example, detecting a malfunction in the rechargeable battery 3 or detecting overcharging of the rechargeable battery 3.

[0032] Furthermore, as shown in Figure 1, the control unit 7 is configured to acquire a voltage V from the rechargeable battery 3 and compare it with a threshold value 60. When the voltage V of the rechargeable battery 3 is less than the threshold value 60, the control unit 7 outputs a control signal S to the switching unit 5 to switch from the second circuit R2 to the first circuit R1. Also, when the voltage V of the rechargeable battery 3 becomes equal to or greater than the threshold value 60, the control unit 7 outputs a control signal S to the switching unit 5 to switch from the first circuit R1 to the second circuit R2.

[0033] (Regarding the first circuit R1 and the second circuit R2) The first circuit R1 is a circuit that passes through the photovoltaic element 2, the switching unit 5, the control unit 7, and the rechargeable battery 3. This first circuit R1 is the circuit that charges the rechargeable battery 3.

[0034] The second circuit R2 is a circuit that passes through the photovoltaic element 2, the switching unit 5, and the grounding circuit 4. This second circuit R2 is a circuit that prevents the power P1 generated by the photovoltaic element 2 from being consumed by itself.

[0035] An example of the operation of the photovoltaic system 1 of this embodiment will be described below with reference to the flowchart in Figure 3.

[0036] (operation) The control unit 7 of the photovoltaic system 1 outputs a control signal S to the switching unit 5 to form the first circuit R1, and starts charging the rechargeable battery 3 based on the power P1 generated by the photovoltaic element 2 (Step 1). The control unit 7 monitors the voltage V of the rechargeable battery 3.

[0037] The control unit 7 compares the voltage V of the rechargeable battery 3 with the threshold value 60 obtained from the memory unit 6. If the stop condition for stopping the charging of the rechargeable battery 3 is not met (Step 2: No), the control unit 7 continues charging (Step 3) and proceeds to Step 2.

[0038] Here, if the stop condition is met in step 2 (Step 2: Yes), the control unit 7 outputs a control signal S to the switching unit 5, electrically connects the photovoltaic element 2 to the grounding circuit 4, switches from the first circuit R1 to the second circuit R2 (Step 4), and proceeds to step 2 to monitor the voltage V of the rechargeable battery 3.

[0039] (Effects of the embodiment) The photovoltaic system 1 according to this embodiment can suppress malfunctions due to self-consumption. Specifically, when the photovoltaic system 1 stops charging the rechargeable battery 3, it connects the photovoltaic element 2 and the grounding circuit 4 to consume the generated power P1 in order to prevent self-consumption. Therefore, compared to a configuration that does not employ this setting, malfunctions due to self-consumption can be suppressed.

[0040] In photovoltaic system 1, since the photovoltaic element 2 is a perovskite solar cell that is sensitive to heat, malfunctions of the photovoltaic element 2 caused by heat can be suppressed compared to when self-consumption is not suppressed. Furthermore, because photovoltaic system 1 can suppress malfunctions of the photovoltaic element 2 due to self-consumption, it is possible to construct a system that takes advantage of the characteristics of perovskite solar cells, such as flexibility and high power generation efficiency.

[0041] The photovoltaic system 1 can consume the power P1 generated by the photovoltaic element 2 via the grounding circuit 4. Compared to a configuration that includes a load device such as a motor as a dedicated load to consume power when charging stops, this system can suppress malfunctions of the photovoltaic element 2 due to self-consumption without compromising the system's lightweight nature. Furthermore, the photovoltaic system 1 can reduce manufacturing costs compared to a configuration that includes the aforementioned load device.

[0042] The photovoltaic system 1 according to the above-described embodiments and modifications may, for example, be partially implemented by a computer program, an ASIC (Application Specific Integrated Circuit), and an FPGA (Field Programmable Gate Array), depending on the application.

[0043] Although several embodiments and modifications of the present invention have been described above, these embodiments and modifications are merely examples and do not limit the invention as defined in the claims. These novel embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Furthermore, not all combinations of features described in these embodiments and modifications are necessarily essential for solving the problem of the invention. Moreover, these embodiments and modifications are included in the scope and spirit of the invention, as well as in the invention described in the claims and its equivalents. [Explanation of Symbols]

[0044] 1...Photovoltaic system, 2...Photovoltaic element, 3...Rechargeable battery, 4...Grounding circuit, 5...Switching unit, 6...Memory unit, 7...Control unit, 8...Load, 9...Light, 60...Threshold, R1...First circuit, R2...Second circuit

Claims

1. A photovoltaic element that converts incident light energy into electrical energy to output power, A rechargeable battery that is charged using the power generated by the photovoltaic element, A grounding circuit for grounding the photovoltaic element, A switching unit that switches the electrical connection between the photovoltaic element and the rechargeable battery, and the electrical connection between the photovoltaic element and the grounding circuit, When the stop condition for stopping the charging of the rechargeable battery is met, the control unit controls the switching unit to switch the electrical connection with the photovoltaic element from the rechargeable battery to the grounding circuit, Equipped with a photovoltaic system.

2. The control unit sets the stop condition as the rechargeable battery being charged to a predetermined capacity, and when this stop condition is met, it controls the switching unit to electrically connect the photovoltaic element and the grounding circuit. The photovoltaic system according to claim 1.

3. The control unit further uses the occurrence of an abnormality in the charging of the rechargeable battery as a stop condition, and when any one of these stop conditions is met, it controls the switching unit to electrically connect the photovoltaic element and the grounding circuit. The photovoltaic system according to claim 1.

4. The rechargeable battery is configured to be removable, The control unit further uses the removal of the rechargeable battery as the stop condition, and when any one of these stop conditions is met, controls the switching unit to electrically connect the photovoltaic element and the grounding circuit. The photovoltaic system according to claim 1.

5. The aforementioned photovoltaic element is a perovskite solar cell. The photovoltaic system according to any one of claims 1 to 4.

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