Solar power generation storage system and control method thereof

Abstract

A photovoltaic power generation charge / discharge device is provided that can realize a highly efficient system that utilizes all surplus power from photovoltaic power generation. [Solution] A solar power generation charging / discharging device 30 has a solar panel connection terminal T31, a storage battery connection terminal T36, a DC connection terminal T33, an MPPT charger CH31, a cutoff switch S31 and a backflow prevention diode D51 provided between the MPPT charger and the DC connection terminal, a bypass diode D31 provided in a circuit that supplies power directly from the solar panel connection terminal to the DC connection terminal, and a control circuit CU31 that controls the cutoff switch based on the state of the MPPT charger output and the output from the storage battery connection terminal, and controls the amount of power supplied from the storage battery connection terminal to the DC connection terminal and from the solar panel connection terminal to the storage battery connection terminal.

Description

[Technical Field]

[0001] The present invention relates to a photovoltaic power generation charging / discharging device that includes a storage battery and is connected to a solar panel to supply power to a load. [Background technology]

[0002] Surplus DC power generated by solar panels (PV) installed in ordinary homes is converted into AC power by a power conditioner (PCS), a charging and discharging device for solar power generation, and then connected to the power transmission grid, which is a commercial power grid.

[0003] Conventionally, in a power supply system equipped with a solar power generation charging / discharging device that converts the power generated by a solar panel from DC to AC and supplies it to a load, power is supplied from the solar power generation system to the load during the day, and a storage battery is charged with surplus power from the solar power generation system or a commercial power source, and power is supplied from the storage battery to the load at night (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7126243 Summary of the Invention [Problem to be solved by the invention]

[0005] The conventional power supply system described above is equipped with a circuit that automatically switches to commercial power even if the power conditioner (PCS) built into the battery fails. The PCS circuit includes two solar panels, a charge / discharge controller, a storage battery, and a bidirectional DC / DC converter. The two charge / discharge controllers and the bidirectional DC / DC converter are connected to the same DC bus. The DC bus is connected to an inverter / converter and linked to the commercial power source. The bidirectional DC / DC converter controls the charging and discharging of the storage battery, and the output of the two charge / discharge controllers and the bidirectional DC / DC converter are controlled to the same DC bus voltage. However, this power supply system suffers from problems such as power conversion loss due to the bidirectional DC / DC power supply, reducing efficiency. It also has a complex circuit configuration. Furthermore, the need to charge the storage battery from commercial power prevents full utilization of renewable energy. Furthermore, the need for switching between modes makes it difficult to ensure a stable power supply.

[0006] As policies related to the SDGs are being promoted, the use of renewable energy, including solar power generation systems, is being promoted. Systems that prioritize renewable energy and can be used outdoors, even in cold climates, are desirable. However, in conventional power supply systems, PCSs, which convert solar power into AC power, convert and output the power generated by solar panels independently of the charge capacity of surrounding batteries or the grid-connected power usage status (electrically connecting electricity from power generation equipment and storage batteries to general transmission and distribution lines). This results in individual, independent operation, or individual optimal operation. Furthermore, storage batteries cannot distinguish between solar panels and commercial power, so they always treat renewable energy and commercial power as a combined power, and are simply temporary energy storage systems that are not configured to fully utilize the renewable energy generation capacity. In the above-mentioned system, when electricity generated by renewable energy is sent to the grid, depending on the situation of the power generation and transmission volume on the grid side, if there is no room for acceptance, for example, the output of renewable energy is suppressed, which has the problem that renewable energy cannot be used effectively. [Means for solving the problem]

[0007] The present invention has been made in view of the above-mentioned problems, and has an object to provide a photovoltaic power generation charging / discharging device that can realize a highly efficient system that utilizes all surplus power generated by photovoltaic power generation.

[0008] A first aspect of the present invention is a solar panel power supply including a solar panel connection terminal connected to a solar panel, a storage battery connection terminal connected to a storage battery, and a DC connection terminal for supplying power to a specific load. an MPPT charger connected to the solar panel connection terminal to control the voltage and current output by the solar panel; a cutoff switch and a backflow prevention diode provided between the MPPT charger and the DC connection terminal; a bypass diode provided in a circuit that supplies power directly from the solar panel connection terminal to the DC connection terminal; a control circuit that controls the cutoff switch based on the state of the output of the MPPT charger and the output from the storage battery connection terminal, and controls the amount of power supplied from the storage battery connection terminal to the DC connection terminal and the amount of power supplied from the solar panel connection terminal to the storage battery connection terminal; and the control circuit comprises: When it is detected that the power output from the solar panel connection terminal exceeds a predetermined value, only the power that exceeds the predetermined value is output from the solar panel connection terminal to the storage battery connection terminal; The present invention provides a charging / discharging device for solar power generation, characterized in that when it detects that the power output from the solar panel connection terminal falls below a predetermined value, only the amount of power that falls below the predetermined value is output from the storage battery connection terminal to the DC connection terminal.

[0009] According to this aspect, a commercial power source is not used, and surplus solar power is efficiently stored in the storage battery, and when the power from the solar power generation becomes insufficient, the storage battery is discharged and supplied to the load, thereby realizing a highly efficient system that utilizes all surplus power from the solar power generation.

[0010] A second aspect of the present invention provides a photovoltaic power generation charging / discharging device including the photovoltaic power generation charging / discharging device of the first aspect of the present invention, characterized in that one or more photovoltaic power generation devices are connected to the solar panel connection terminal, and a DC / AC inverter is provided between the DC connection terminal and a specific load. By incorporating an efficient charging / discharging device, a highly efficient system that utilizes all surplus power from photovoltaic power generation can be realized without using a commercial power source.

[0011] Furthermore, it is preferable that an external power supply is provided between the DC connection terminal and the DC / AC inverter, and when the control circuit detects that the power output from the DC connection terminal falls below a predetermined value, the external power supply outputs only the power that falls below the predetermined value to the DC / AC inverter. Since the external power supply is located closer to the inverter than the solar power generation charging / discharging device, all surplus power from the solar power generation is used, resulting in high efficiency, and even when there is no solar power generation power and discharging from the storage battery is stopped, voltage changes can be reduced, resulting in a stable power supply.

[0012] It is also preferable that the photovoltaic power generation charging / discharging device includes a plurality of the photovoltaic power generation charging / discharging devices of the first aspect of the present invention, each having a photovoltaic power generation device connected to the solar panel connection terminal, and each DC connection terminal is connected to the external power supply and the DC / AC inverter via a single DC-BUS line. This allows all surplus power from photovoltaic power generation to be utilized, resulting in high efficiency, and also makes it possible to expand both the amount of photovoltaic power generation and the storage battery capacity.

[0013] Alternatively, it is preferable that the wiring connected to a plurality of photovoltaic power generation devices is combined into a single wiring, and that the wiring is redistributed and connected to the solar panel connection terminals of each of the photovoltaic power generation charging / discharging devices of the first aspect of the present invention, in which a plurality of devices are connected in parallel, and that the control circuits of all the photovoltaic power generation charging / discharging devices are collectively controlled and communicated with each other, and that each DC connection terminal is connected to the external power supply and the DC / AC inverter via a single DC-BUS line. This is highly efficient as it can fully utilize surplus power from photovoltaic power generation, and furthermore, it makes it possible to expand both the amount of photovoltaic power generation and the storage battery capacity, and it reduces the number of wirings, thereby reducing the material costs of the wires and the installation costs.

[0014] Furthermore, it is preferable that the control circuit performs synchronous operation with one of the photovoltaic power generation charging / discharging devices as a master photovoltaic power generation charging / discharging device and the other photovoltaic power generation charging / discharging devices as slaves, and that the MPPT charger has a switch for changing the maximum charging current value between three or more fixed levels, allowing it to be set according to local conditions.

[0015] A third aspect of the present invention provides a control method for a solar power generation storage system according to the second aspect, wherein the control circuit performs synchronous operation of one of the solar power generation charging / discharging devices as a master and the other as slaves, detects the total input power and total output power of all the solar power generation charging / discharging devices, and varies the maximum charging current value for all the MPPT chargers so that the total input power is greater than the total output power. This control method is highly efficient because it can fully utilize surplus solar power generation, and further enables the expansion of both solar power generation and storage battery capacity, reduces the number of wirings, and reduces wiring material and installation costs. Furthermore, it minimizes voltage fluctuations even in facilities with large power generation capacity, enabling a stable power supply. Furthermore, it allows the capacity of each storage battery to be selected so as to fully use environmental energy. [Effects of the Invention]

[0016] According to the present invention, a highly efficient system that utilizes all surplus power generated by solar power generation can be realized. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram showing the configuration of a photovoltaic power generation charging / discharging device according to a first embodiment of the present invention. [Figure 2] This is an IV characteristic diagram of a 450W solar module. [Figure 3] This is an IV characteristic diagram of a 2.7kW solar module. [Figure 4] FIG. 3 is a diagram illustrating a static control method for the MPPT charger of the solar power generation charging / discharging device according to the first embodiment of the present invention. [Figure 5] FIG. 10 is a diagram showing the configuration of a solar power generation electricity storage system according to a second embodiment of the present invention. [Figure 6] FIG. 10 is a diagram showing the configuration of a solar power generation electricity storage system according to a third embodiment of the present invention. [Figure 7] FIG. 10 is a diagram showing set voltage values ​​and power conversion in a photovoltaic power generation charging / discharging device according to a third embodiment of the present invention. [Figure 8] FIG. 10 is a diagram showing the amount of solar power generation and the state of power usage in the solar power generation power storage system according to the third embodiment of the present invention. [Figure 9] FIG. 10 is a diagram showing the configuration of a solar power generation electricity storage system according to a fourth embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing the configuration of a solar power generation electricity storage system according to a fifth embodiment of the present invention. [Figure 11] FIG. 10 is a diagram showing the configuration of a solar power generation electricity storage system according to a sixth embodiment of the present invention. [Figure 12] FIG. 10 is an explanatory diagram of synchronous operation and charge control of an MPPT charger in a solar power generation power storage system according to a sixth embodiment of the present invention. [Figure 13] 13 is an example of a flow chart showing a control method in a solar power generation electricity storage system according to a sixth embodiment of the present invention, in which a PVV voltage is compared with a DCV voltage and a maximum charging constant current value is variably controlled. DETAILED DESCRIPTION OF THE INVENTION

[0018] Example 1 1 is a diagram showing the configuration of a solar power generation charging / discharging device according to a first embodiment of the present invention. The solar power generation charging / discharging device (30) of the first embodiment includes solar panel connection terminals (T31, T32) connected to a solar panel, storage battery connection terminals (T35, T36) connected to a storage battery (20), DC connection terminals (T33, T34) for supplying power to a specific load, an MPPT charger (CH31) connected to the solar panel connection terminal (T31) for controlling the voltage and current output by the solar panel, and a cutoff switch (S31) and a backflow prevention diode (B31) provided between the MPPT charger (CH31) and the DC connection terminal (T33). a bypass diode (D31) provided in a circuit that supplies power directly from the solar panel connection terminal (T31) to the DC connection terminal (T33); and a control circuit (CU31) that controls a cutoff switch (S31) based on the state of the output of the MPPT charger (CH31) and the output from the storage battery connection terminal (T35), and selects between power supply from the storage battery connection terminal (T35) to the DC connection terminal (T33) and power supply from the solar panel connection terminal (T31) to the storage battery connection terminal (T35).

[0019] Furthermore, in the solar power generation charging / discharging device (30) of Example 1, when the control circuit (CU31) detects that the power output from the solar panel connection terminal (T31) exceeds a predetermined value, only the power that exceeds the predetermined value is output from the solar panel connection terminal (T31) to the storage battery connection terminal (T35), and when the control circuit (CU31) detects that the power output from the solar panel connection terminal (T31) falls below the predetermined value, only the power that falls below the predetermined value is output from the storage battery connection terminal (T35) to the DC connection terminal (T33).

[0020] In the photovoltaic power generation charging / discharging device (30) of Example 1, power generated by the photovoltaic power generation device is input to an MPPT charger (CH31) from a solar panel connection terminal (T31) of the photovoltaic power generation charging / discharging device (30), i.e., a PV input terminal, and the output of the MPPT charger (CH31) is connected to the storage battery (20) and also to a backflow prevention diode (D32) via a cutoff switch (S31). The output of the backflow prevention diode (D32) is connected to an output terminal, which is a DC connection terminal (T33) of the charging / discharging device 30. The input from the solar panel connection terminal (T31) is connected to the output of the backflow prevention diode (D32) via a bypass diode (D31) and is output from the DC connection terminal (T33), which is a DC output terminal of the photovoltaic power generation charging / discharging device (30).

[0021] In the solar power generation charging / discharging device (30) of the first embodiment, the power input from the solar power generation device is input to an MPPT charger (CH31), and MPPT control is performed to charge the storage battery (20) connected to the storage battery connection terminal (T35), i.e., the battery input terminal, at a constant voltage / constant current.

[0022] The MPPT charger (CH31) is an MPPT charge / discharge controller used to store electricity from solar panels in a storage battery, and uses the maximum power point tracking (MPPT) method. MPPT chargers automatically determine the current and voltage values ​​that can be output with maximum efficiency. MPPT (Maximum Power Point Tracking) is a control method that automatically determines the optimal current x voltage value (maximum power point, or optimal operating point) that maximizes output when solar cells are generating electricity.

[0023] The output of the MPPT charger (CH31) and the input / output from the storage battery (20) intersect at the intersection P1 from the battery input terminal, which is the storage battery connection terminal (T35), and are connected to the circuit breaker (S31), and are output to the outside from the DC connection terminal (T33), i.e., the DC output terminal, via the backflow prevention diode (D32).

[0024] Therefore, in this case, the output from the DC output terminal, which is the DC connection terminal (T33), is the combined output of the MPPT charger (CH31) output and the storage battery (20), or when the output of the MPPT charger (CH31) is stopped, the output is from the storage battery (20) via the backflow prevention diode (D32).

[0025] Power for the control circuit (CU31) of the MPPT charger (CH31) is input from the same path as the intersection P1, and is supplied from the storage battery (20) even if there is no output from the MPPT charger (CH31). The cutoff switch (S31) is cut off when a BMS (battery management system) built into the storage battery (20) detects over-discharge or an abnormality of the storage battery and inputs an abnormality signal to the control circuit (CU31), and an ON / OFF signal that stops discharge from the storage battery (20) is input to the cutoff switch (S31).

[0026] Therefore, the output of the MPPT charger (CH31) and the output from the storage battery (20) pass through the intersection P1, the cutoff switch (S31) and the backflow prevention diode (D32) and are output as DC from the DC connection terminal (T33).

[0027] In the photovoltaic power generation charging / discharging device (30) of Example 1, the PV input terminal, which is the solar panel connection terminal (T31), is further connected to the DC connection terminal (T33) via the bypass diode (D31), and the output of photovoltaic power generation from the PV input terminal, which is the solar panel connection terminal (T31), is DC output only when it is higher than the output voltages of the MPPT charger (CH31) and the storage battery (20). The bypass diode (D31) functions to output a DC voltage depending on whether the voltage is high or low.

[0028] Therefore, in the solar power generation charging / discharging device (30) of the first embodiment, the power input from the solar power generation has two paths: the power that charges the storage battery (20) using the MPPT charger (CH31) and the power that is directly output via the bypass diode (D31). Also, when the voltage value input from the solar power generation is lower than the voltage value of the storage battery (20), DC is output from the storage battery (20) via the cutoff switch (S31) and the backflow prevention diode (D32).

[0029] Next, the MPPT charger (CH31) of the solar power generation charging / discharging device 30 of Example 1 will be described. Fig. 2 is an IV characteristic diagram of a 450 W solar module. Fig. 3 is an IV characteristic diagram of a 2.7 kW solar module. Figs. 2 and 3 show the relationship between the amount of power generation and the illuminance of the solar panel, with the difference being (1) 1000 W / m 2 , (2) 800 W / m 2 , (3) 600 W / m 2 , (4) 400 W / m 2 , (5) 200 W / m 2 2 shows an example of an IV curve characteristic, with the curves including circles indicating the I × V power values ​​for each of (1) to (5). FIG. 3 shows the IV characteristics when six 450W solar modules as shown in FIG. 2 are connected in series, resulting in a solar power generation IV characteristic with a solar power generation output of 450W x 6 series = 2700W = 2.7kW. In FIGS. 2 and 3, the dotted curves indicate the current value versus the voltage value, and the solid curves indicate the output value versus the voltage value. In FIG. 2, the maximum output is 450W, the maximum output operating voltage is 41V, and the maximum output operating current is 11A (see the circled portion of the solid line (1)). In FIG. 3, the maximum output is 2700W, the maximum output operating voltage is 246V, and the maximum output operating current is 11A (see the circled portion of the solid line (1)). The control circuit (CU31) controls the amount of power supplied from the storage battery connection terminal to the DC connection terminal, and also controls the amount of power supplied from the solar panel connection terminal to the storage battery connection terminal.

[0030] The MPPT charger (CH31) is designed to measure the power generation amount (1) of 1000W / m2 depending on the illuminance of the solar panel in the IV characteristics of the solar power generation module. 2 , (2) 800 W / m 2 , (3) 600 W / m2 , (4) 400 W / m 2 , (5) 200 W / m 2 The MPPT charger converts input power into output power for the battery by tracking the maximum power point (circle).

[0031] FIG. 4 illustrates a static control method for the MPPT charger of the solar power generation charging / discharging device according to the first embodiment of the present invention. The MPPT charger (CH31) controls charging of the storage battery by outputting a constant current and constant voltage of 174 V for charging currents of 3 A, 7 A, and 14 A. In FIG. 4, the MPPT charger's maximum charging voltage is 174 V and its over-discharge cutoff voltage is 130 V. FIG. 4 shows a charging curve obtained by charging the storage battery under this control, with the horizontal axis representing time. When the storage battery voltage is below the maximum charging voltage, charging is performed under constant voltage control (in the example of FIG. 4, a charging current of 7 A or 14 A can be selected). When the battery voltage reaches the maximum charging voltage, charging is switched from constant current control to constant voltage control. Under constant voltage control, the charging current gradually decreases in proportion to the charge amount (see the dashed line in FIG. 4). If the constant charging current is selected as 7A or 14A, the rechargeable battery power will be 1.2kW (≒7A x 174V) / 2.4kW.

[0032] According to the photovoltaic power generation charging / discharging device of the first embodiment of the present invention, a commercial power source is not used, and the surplus power generated by the photovoltaic power generation is efficiently stored in a storage battery, and when the power from the photovoltaic power generation becomes insufficient, the storage battery is discharged and supplied to the load, thereby realizing a highly efficient system that utilizes all the surplus power generated by the photovoltaic power generation.

[0033] <Example 2> Fig. 5 is a diagram showing the configuration of a solar power generation electricity storage system according to a second embodiment of the present invention. The solar power generation electricity storage system (80) of the second embodiment includes the solar power generation charging / discharging device (30) of the first embodiment shown in Fig. 1, one or more solar power generation devices (10) are connected to solar panel connection terminals (T31, T32), and a DC / AC inverter (40) is provided between the DC connection terminals (T33, T34) and a specific load.

[0034] The solar modules of the solar power generation device (10) are configured by connecting a plurality of single modules in series, and when the series-connected solar modules are connected in parallel, they are configured with backflow prevention diodes (D10, D11) that prevent backflow of current between the plurality of solar modules and backflow of current from the solar power generation charging / discharging device (30).

[0035] The solar power generation device (10) is connected to the input terminal, which is the solar panel connection terminal (T31) of the solar power generation charging / discharging device (30), and similarly, the DC / AC inverter (40) is connected to the output terminal, which is the DC connection terminal (T33).

[0036] In the solar power generation charging / discharging device (30), power from the solar power generation device (10) is input to a PV input terminal, which is a solar panel connection terminal (T31), passes through a bypass diode (D31), and is output from a DC output, which is a DC connection terminal (T33), to a DC / AC inverter (40). Also, power is input from the PV input, which is the solar panel connection terminal (T31), to an MPPT charger (CH31), and its output is connected to the storage battery (20), a cutoff switch (S31), a backflow prevention diode (D32), the bypass diode (D31), and is input to the DC / AC inverter (40).

[0037] Therefore, in the solar power generation power storage system (80) of the second embodiment, the MPPT charger (31) charges the storage battery (20), and power is supplied to the DC / AC inverter (40) from both the output via the backflow prevention diode (D32) and the output from the solar power generation device (10) via the bypass diode (D31).

[0038] When the output from the MPPT charger (CH31) and the storage battery (20) is higher than the voltage of the bypass diode (D31) from the PV input, which is the solar panel connection terminal (T31), the output is discharged via the backflow prevention diode (D32), and when the voltage of the bypass diode (D31) is higher than the voltage of the backflow prevention diode (D32), the output is discharged via the bypass diode (D31).

[0039] Therefore, in the solar power generation power storage system (80) of the second embodiment, the power from the solar power generation device (10) and the power from the storage battery (20) are separated by a bypass diode (D31) and supplied to the DC / AC inverter (40). The output of the DC / AC inverter (40) is connected to a specific load as an independent power source. The DC / AC inverter (40) may be a power conditioner connected to a grid.

[0040] According to the solar power generation power storage system (80) of the second embodiment, even if there is no power from sunlight (such as on a rainy day or at night when there is no solar power generation), power is automatically discharged from the storage battery. Therefore, in response to unstable power generated by solar power generation (such as a drop or rise in the solar power generation), power can be automatically supplied from the storage battery, and power can be continuously supplied to the DC / AC inverter.

[0041] According to the solar power generation electricity storage system of the second embodiment of the present invention, by incorporating an efficient charging / discharging device, a highly efficient system can be realized that utilizes all surplus power from solar power generation without using a commercial power source.

[0042] Example 3 Fig. 6 is a diagram showing the configuration of a solar power generation electricity storage system according to a third embodiment of the present invention. The solar power generation electricity storage system (81) of the third embodiment includes the solar power generation charging / discharging device (30) of the first embodiment shown in Fig. 1, has one or more solar power generation devices (10) connected to solar panel connection terminals (T31, T32), has an external power supply (50) provided between DC connection terminals (T33, T34) and a DC / AC inverter (40), and when a control circuit (CU31) detects that the power output from the DC connection terminal (T33) falls below a predetermined value, outputs only the power by which the power falls below the predetermined value from the external power supply (50) to the DC / AC inverter (40).

[0043] The solar power generation power storage system (81) of the third embodiment includes an external power supply (50) at the input of the DC / AC inverter (40). The external power supply (50) may be a commercial power supply, a generator, or a combination thereof. The power from the external power supply may be 100V AC or 200V AC.

[0044] The external power supply (50) performs AC / DC conversion to output DC. The input of the external power supply (50) and the output of the DC / AC inverter (40) may be of any type, such as a single-phase two-wire system, a single-phase three-wire system, or a three-phase three-wire system. By setting the voltage value to a set discharge stop voltage value during discharge from the storage battery (20), it is possible to supply power to the DC / AC inverter (40) using the DC output from the external power supply (50) even when there is no power from the solar power generation device (10) and discharge from the storage battery (20) has stopped.

[0045] In the solar power generation power storage system (81) of the third embodiment, the DC output voltage of the external power supply (50) is set to a discharge stop setting voltage. In the solar power generation power storage system (81) of the third embodiment, the voltage of the storage battery from a fully charged state to immediately before the discharge stops is higher than the output voltage of the external power supply (50), and therefore no output is generated from the external power supply (50) during that period. In addition, the outputs of the bypass diode (D31), the backflow prevention diode (D32), and the backflow prevention diode (D51) are connected to the input of the DC / AC inverter (40). Therefore, switching is performed such that the output voltages of the bypass diode (D31) and the backflow prevention diode (D32) gradually decrease relative to the voltage of the backflow prevention diode (D51), thereby gradually increasing the output from the backflow prevention diode (D51).

[0046] The solar power generation storage system (81) of Example 3 is a power supply system including a solar power generation device (10) equipped with a solar panel and a solar power generation charging / discharging device (30), a DC / AC inverter (40) connected to a storage battery (20), and an output from the storage battery (20) that performs DC / AC conversion via a backflow prevention diode (D51), a diode (isolation diode) that separates the output from the solar panel and the output from the storage battery between the output from the solar panel and the input to the DC / AC inverter, and an external power supply (50) (AC / DC) at the input to the DC / AC inverter that supplies power when the output from the solar power generation device (10) and the storage battery (20) stops.

[0047] The solar power generation electricity storage system (81) of the third embodiment can reduce voltage changes and supply stable power to the inverter (40).

[0048] The solar power generation power storage system (81) of the third embodiment is configured by adding an external power supply (50) to the solar power generation power storage system (80) of the second embodiment, and the input power is supplied from the external power supply (50), and the AC / DC converted DC output is connected to the input of the DC / AC inverter (40) via a backflow prevention diode (D51).

[0049] The output power of the external power supply (50) is supplied via a backflow prevention diode (D51) before the power of the solar power generation device (10) is exhausted and the capacity of the storage battery decreases to a discharge stop voltage, thereby preventing the output power of the DC / AC inverter (40) from being stopped.

[0050] Therefore, the solar power generation electricity storage system (81) of the third embodiment continues to operate the DC / AC inverter (40) with the power from the external power supply (50).

[0051] FIG. 7 is a diagram illustrating set voltage values ​​and power conversion in a solar power generation charging / discharging device according to a third embodiment of the present invention. FIG. 7 illustrates a specific example of control voltage settings in a solar power generation storage system (81) according to the third embodiment. In FIG. 7, the output voltage of DC 100 V to DC 320 V generated from 5.4 kW solar power generation power (10) passes through an MPPT charger (31) and a bypass diode (D31) and is input to a DC / AC inverter (40). Note that in FIG. 7, the 5.4 kW generated power of the solar power generation device is obtained by configuring 6 series x 2 parallel 450 W solar modules shown in FIG. 2, with a maximum output operating voltage of 246 V and a maximum output operating current of 11 A. In FIG. 7, the capacity of the storage battery (20) is 4.8 kWh, with a nominal voltage of DC 160 V and a nominal current of DC 30 A. These are merely examples and are not limited to the above values.

[0052] The solar power (5.4 kW) input to the MPPT charger (31) is charged into the storage battery (20) under MPPT control. The charging curve at this time is shown in Figure 4. Charging is performed under constant current and constant voltage control, with the charging current set to 14 A and the maximum charging voltage of the MPPT charger set to 174 V. In this case, the amount of charging power is 2.4 kW (≒ 14 A x 174 V).

[0053] On the other hand, the solar power generation (power generation amount: 5.4 kW) is input to the DC / AC inverter (40) via the bypass diode (D31). Here, the solar power generation amount of 5.4 kW is charged by the 2.4 kW MPPT charger (31), and the power of 3.0 kW (5.4 kW - 2.4 kW) obtained by subtracting the 2.4 kW charged by the MPPT charger (31) from the solar power generation amount of 5.4 kW is input to the DC / AC inverter (40) via the bypass diode (D31).

[0054] Therefore, in the solar power generation power storage system (81) of Example 3, when the amount of power generated by solar power generation of 5.4 kW varies depending on the illuminance during the day, if the amount of power generated is 2.4 kW or less, it is converted into charging power by the MPPT charger (31), and the sum of this charging power and the discharge power from the storage battery (20) is input to the DC / AC inverter (40) via the cutoff switch (S31) and the backflow prevention diode (D32). Also, power generated by a power output of 2.4 kW or more is input to the DC / AC inverter (40) via the bypass diode (D31), and is DC / AC converted to AC, and AC 200 V is supplied to the specific load, and surplus power remaining after subtracting the power supplied to the specific load from the solar power generation power is charged to the storage battery (20) via the MPPT charger (31).

[0055] In the solar power generation power storage system (81) of the third embodiment, the condition for discharging from the storage battery (20) is that power is output via the cutoff switch (S31) and the backflow prevention diode (D32) when the output voltage of the bypass diode (D31) becomes lower than the output voltage from the storage battery (20). That is, when the solar power generation power is equal to or lower than 2.4 kW of charging power of the MPPT charger (31), the storage battery (20) is discharged.

[0056] According to FIG. 7, the charging voltage of the storage battery (20) is DC 130V to DC 174V, and the storage battery voltage is in the voltage range of 130V to 174V.

[0057] In this embodiment, charging is controlled by constant current and constant voltage control, as shown in Fig. 7. Therefore, when the voltage supplied from the solar power generation system (10) via the bypass diode (D31) is higher than the above-mentioned storage battery voltage, the output of the bypass diode (D31) is given priority, and when the voltage is lower than the above-mentioned storage battery voltage, the output from the storage battery (20) via the breaker (S31) and the backflow prevention diode (D32) is given priority and supplied to the DC / AC inverter (40).

[0058] The storage battery (20) has a storage battery capacity of 4800Wh (4.8kWh), a nominal voltage of 160V, and a nominal current of 30A.

[0059] Power input from the external power supply (50) is AC / DC converted, and in the example of FIG. 7, DC 150V is input to the DC / AC inverter (40). The function of this external power supply (50) is that when the output from the solar power generation system (10) and the output voltage from the storage battery via the cutoff switch (S31) and the backflow prevention diode (D32) drop below DC 150V, the output from the external power supply (50) is given priority and input to the DC / AC inverter (40). In FIG. 7, the maximum charging voltage of the MPPT charger is set to 174V, the over-discharge stop voltage is set to 130V (the voltage value at which the cutoff switch (S31) switches from ON to OFF), and the power conversion capacity of the MPPT charger is 2.4kW (≈14A×174V). In FIG. 7, the voltage output from the external power supply is DC 150V, and when the voltage output from the solar power generation system and the voltage discharged from the storage battery drop below the voltage output from the external power supply, power supply from the external power supply is automatically started.

[0060] 8 is a diagram showing the amount of solar power generation and the state of power usage in a solar power generation storage system according to a third embodiment of the present invention. When the amount of solar power generation decreases or becomes zero (such as at night) or when the storage battery capacity decreases and the storage battery voltage becomes equal to or lower than DC 150 V of the external power supply (50), power from the external power supply (50) is input to the DC / AC inverter (40), and power can be supplied from the DC / AC inverter (40) to the fixed load without interruption. The DC 150 V voltage of the external power supply (50) is set within a voltage range equal to or higher than the over-discharge stop voltage (DC 130 V) of the storage battery and equal to or lower than the maximum charging voltage.

[0061] As shown in FIG. 8, an example of daily power usage with specific control voltage settings is shown. For example, at midnight, there is no solar power generation because it is nighttime, and the storage battery voltage is below DC 150. Therefore, power is supplied from the external power source (50) to the DC / AC inverter (40), and AC 200V / 2kW is output to the specific load. At 6:00, solar power generation begins, and the amount of power generated gradually increases. As the output power of the external power source (50) gradually decreases, the output of the external power source (50) becomes 0W and switches to solar-generated power when the solar power generation is in the range of 2kW to 2.4kW. When the amount of solar power generation exceeds 2.4kW, assuming that the amount of power used by the DC / AC inverter (40) is 2kW, power greater than this power is charged to the storage battery (20) as charging power. Then, in the evening after 3:00PM, the amount of solar power generation decreases. When the solar power generation is in the range of 2kW to 2.4kW, the power stored during the day begins to be discharged from the storage battery (20). As the solar power generation decreases, the discharged power from the storage battery (20) increases as the solar power generation power decreases. In this embodiment, at 5:00 PM, the DC / AC inverter (40) operates with 100% of the power discharged from the storage battery (20). The time for which the storage battery (20) can be discharged is determined by the storage battery capacity. For example, if the storage battery capacity is 4.8 kWh, in this embodiment, the storage battery can operate for 2 hours at a 2 kW output. Therefore, after 7:00 PM, when the storage battery voltage falls below DC 150 V, which is the output voltage from the external power supply (50), the discharge power from the storage battery gradually decreases, and the output power of the external power supply (50) increases, so that the DC / AC inverter (40) continues to output 2 kW using the power of the power supply (50).

[0062] According to this embodiment, the power storage system automatically switches between photovoltaic power generation power, storage battery power, and power from an external power source (50) from a commercial power source or a generator input (referred to as external power) at each voltage value.

[0063] In the solar power generation power storage system (81) of the third embodiment, charging from the solar power generation device (10) is performed by an MPPT charger (CH31), but discharging is performed by a backflow prevention diode (D32) via a cutoff switch (S31), resulting in highly efficient discharging without the need for power conversion. A bypass diode (D31) is provided between the output of the solar power generation device (10) and the output of the backflow prevention diode (D32). Therefore, surplus power (power not used for purposes other than charging) remaining after subtracting charging power from the amount of solar power generation is input to the DC / AC inverter (40), allowing all of the solar power to be utilized. Therefore, according to this embodiment, highly efficient discharging from the storage battery is achieved, thereby realizing a highly efficient system that fully utilizes surplus solar power generation.

[0064] In the solar power generation power storage system of the third embodiment of the present invention, a solar power generation charging / discharging device (30) is connected to a solar power generation device (10) and has two paths: a path for charging a storage battery (20) and a bypass diode (D31) between the input and output of the solar power generation charging / discharging device (30). The solar power generation charging / discharging device (30) is provided with an MPPT charger (CH31) that performs MPPT control of solar power generation power to charge the storage battery (30). On the other hand, power is output from a connection point between the MPPT charger (CH31) and the storage battery (30) via a cutoff switch (S31) and a backflow prevention diode (D32). An AC output that is input to a DC / AC inverter (40) from an intersection P1 of a first output from the storage battery (30) and a second output of the bypass diode (D31) and converted into DC / AC is supplied to a specific load. A third DC output from an external power source (50) is input to the DC / AC inverter (40). Therefore, The first storage battery output, the second photovoltaic power generation output, and the third external power supply output are each connected by a diode and input to the DC / AC inverter (40), and the storage battery system automatically makes available to the DC / AC inverter power in the order of the second output > the first output > the third output, starting with the highest voltage. Therefore, according to this embodiment, the solar power generation power is automatically supplied to the DC / AC inverter and simultaneously supplied to charge the storage battery, or is automatically supplied only for charging. When the voltage generated by sunlight is lower than the voltage of the storage battery, the storage battery is automatically discharged. When the capacity of the storage battery decreases, automatic switching is performed from the external power supply to the DC / AC inverter. This eliminates the need for a complex control circuit for switching between the various power sources, and the power switching is not a sudden ON / OFF method but a gradual change in the amount of power, thereby enabling the construction of a low-stress, low-noise, and low-cost system with no transient power loss.

[0065] According to the solar power generation storage system of Example 3 of the present invention, the external power supply is located closer to the inverter than the solar power generation charging / discharging device, so there is no commercial power supply within the solar power generation charging / discharging device, and all surplus power from solar power generation is used, making it highly efficient.Even when there is no power from solar power generation and discharging from the storage battery has stopped, voltage changes can be reduced, making it possible to provide a stable power supply.

[0066] Example 4 FIG. 9 is a diagram showing the configuration of a solar power generation storage system according to a fourth embodiment of the present invention. The solar power generation storage system (82) according to the fourth embodiment includes a plurality of solar power generation charging / discharging devices (30) according to the first embodiment, each having a solar power generation device connected to its solar panel connection terminal (T31-1 to T31-4), and each DC connection terminal is connected to an external power source (50) and a DC / AC inverter (40) via a single DC-BUS line (70). The DC-BUS line (70) is a DC-BUS line for supplying power to the inverter. The external power source (50) may be a commercial power source, a generator, or a combination of these. The power from the external power source may be 100V AC or 200V AC. The external power source (50) outputs DC by AC / DC conversion.

[0067] In the solar power generation power storage system (82) of the fourth embodiment, the solar power generation device (100) is configured as four circuits for 2.7 kW solar power, and each 2.7 kW of solar power is connected to the solar power generation charging / discharging device (30-33) of the first embodiment. Each of the solar power generation charging / discharging devices (30-33) is connected to a storage battery (20-23). ​​The output terminals, which are DC connection terminals (T33), of the solar power generation charging / discharging devices (30-33) are connected to the same DC bus line (70) and are connected to a backflow prevention diode (D51) of the external power supply (50) and a DC / AC inverter (40). FIG. 3 shows the solar power generation IV characteristics of one 2.7 kW solar power generation circuit of this embodiment.

[0068] The input of the external power supply (50) and the output of the DC / AC inverter (40) are not limited to single-phase two-wire, single-phase three-wire, or three-phase three-wire. The solar power generation power storage system (82) of the fourth embodiment is a power storage system that can be freely configured with multiple solar power generation charging / discharging devices (four devices are shown in FIG. 9 ) and can expand the solar power generation capacity and storage battery capacity. That is, according to this embodiment, the number of solar power generation charging / discharging devices can be freely set as needed, allowing for flexible design of the solar power generation amount and storage battery capacity. Furthermore, the storage batteries (20-23) are preferentially discharged starting from the battery with the higher battery voltage (i.e., the higher capacity). This has the advantage that the voltage drops as the battery voltages converge to the same voltage (i.e., the capacity of each battery is approximately the same). Therefore, even if there is variation in the charge capacity of each storage battery due to solar power generation, discharging from the storage batteries can reduce the variation in the capacity of each storage battery.

[0069] The solar power generation storage system (82) of the fourth embodiment realizes expansion of the storage system by connecting a solar power generation device (100) consisting of a solar string, which is a circuit unit in which solar panels are connected in series, to multiple inputs of each solar power generation charging / discharging device (30-33), and connecting the outputs of the multiple solar power generation charging / discharging devices (30-33) in parallel.

[0070] In conventional solar power generation energy storage systems, expansion requires the installation of multiple batteries and bidirectional DC / DC converters. The capacity of the multiple installed storage batteries is unbalanced because each battery discharges using a DC / DC power supply. Furthermore, repeated charging and discharging in this state can cause the discharge stops of each storage battery at different times. This creates the possibility of a mixture of discharging and non-discharging storage batteries, making it necessary to manage and control the capacity of each storage battery individually. If a storage battery cannot be discharged, it becomes necessary to consider the dischargeable current and manage overcurrent, which complicates the control method and increases the cost of the control circuit.

[0071] According to the solar power generation energy storage system (82) of the fourth embodiment, during discharge, the output via the cutoff switch (S31) and the backflow prevention diode (D32) is on the same DC bus line (70), and therefore, when there is a high capacity (high battery voltage) and a low capacity (low battery voltage), the capacity of the battery with the higher capacity decreases first and reaches the same voltage value as the battery voltage of the battery with the lower capacity. Therefore, in the solar power generation energy storage system (82) of the fourth embodiment, discharge progresses and the voltage values ​​automatically become uniform, thereby discharging while reducing capacity variations.

[0072] The solar power generation energy storage system (82) of Example 4 has a circuit system in which the imbalance in the capacities of the multiple storage batteries is equalized by discharging the multiple storage batteries, and does not require individual discharge control to reduce the capacity variation of the multiple storage batteries. The multiple storage batteries can be operated up to the discharge stop voltage without stopping any of them, and the control circuit that manages the discharge of the multiple storage batteries can be simplified. This simplifies the entire energy storage system and is expected to reduce costs.

[0073] According to this embodiment, the capacity of each storage battery is equalized by discharging, so even if charging and discharging are repeated, the variation in capacity of each storage battery does not increase, and stable charging and discharging operation is possible.

[0074] In this embodiment, the output from one unit of photovoltaic power generation device (100) is input to a photovoltaic power generation charging / discharging device (30), and a plurality of pairs of photovoltaic power generation devices and photovoltaic power generation charging / discharging devices are input in parallel, and the outputs of the plurality of photovoltaic power generation charging / discharging devices are connected to the same DC bus line, and two paths, each with a bypass diode (D31), are provided between the input and output of the photovoltaic power generation charging / discharging device, and the photovoltaic power generation charging / discharging device charges the storage battery (20) with solar-generated power via a path equipped with a control circuit for performing MPPT control, while output is made from a connection point between the MPPT charger (CH31) and the storage battery (20) via a cutoff switch (S31) and a backflow prevention diode (D32), and a first output from the storage battery (20) and a second output of the bypass diode (D31) are connected to a DC-BUS line (70), and the outputs of the plurality of photovoltaic power generation charging / discharging devices are all connected to the DC-BUS line (70), and the AC output that is input to a DC / AC inverter (40) and converted to DC / AC is supplied to a specific load. and a third DC output from an external power source (50) generated by external power is input to the DC / AC inverter (40). Therefore, according to this embodiment, the first storage battery output is output from the plurality of photovoltaic power generation charging / discharging devices, and the plurality of second photovoltaic power generation outputs and the third external power supply output are connected by diodes and input to the DC / AC inverter (40). Of these three output voltages, the outputs are automatically made available to the DC / AC inverter in the order of higher voltage, i.e., the second plurality of photovoltaic power generation outputs > the first plurality of storage batteries > the third external power supply output. The photovoltaic power is automatically supplied to the DC / AC inverter and to charge the storage battery simultaneously, or is automatically supplied only for charging. When the voltage generated by sunlight is lower than the voltage of the storage battery, the storage battery is automatically discharged. When the capacity of the storage battery decreases, control is performed to automatically switch from the external power source to the DC / AC inverter. Therefore, no complex control circuit is required for switching between the various power sources, and one or any number of photovoltaic power generation charging / discharging devices can be easily configured. For example, by installing n storage systems, each pairing a solar power generation capacity of 2.7 kW with a storage battery (for example, a capacity of 4.8 kW), the solar power generation and storage battery capacities can be expanded n times. Note that this embodiment also achieves the effects of the solar power generation storage system of embodiment 3.

[0075] According to the solar power generation storage system of Example 4 of the present invention, there is no commercial power source in the solar power generation charging / discharging device, and all surplus power from solar power generation can be utilized, making it highly efficient, and furthermore, both the amount of solar power generation and the storage battery capacity can be expanded.

[0076] <Example 5> Fig. 10 is a diagram showing the configuration of a solar power generation energy storage system according to a fifth embodiment of the present invention. In the solar power generation energy storage system (83) of the fifth embodiment, the wiring connected to a plurality of solar power generation devices (100) (four circuits of solar power generation devices in Fig. 10) is combined into a single wiring (P100), and the wiring is redistributed (P30-33) from the single wiring and connected to the solar panel connection terminals (T31-1-4) of the solar power generation charging / discharging devices (30-33) of the first embodiment, which are connected in parallel, and the control circuits of all the solar power generation charging / discharging devices (30-33) are collectively controlled and communicated with each other, and the DC connection terminals (T33-1-4) are connected to an external power source (50) and a DC / AC inverter (40) via a single DC-BUS line (70).

[0077] Although the solar power generation storage system (82) of the fourth embodiment described above can also reduce costs considerably, in the fourth embodiment, it is necessary to wire each of the four circuits of the solar power generation device (100) to the input of the solar power generation charging / discharging devices (30-33). Therefore, if there is a distance between the solar power generation device (100) and the solar power generation charging / discharging devices (30-33) installed, or if the number of circuits of the solar power generation device (100) and the solar power generation charging / discharging devices (30-33) installed is large, it is necessary to wire a power line for each solar power generation charging / discharging device. Therefore, the amount of wiring for the power lines connecting the solar power generation device (100) consisting of a solar string and the inputs of each of the solar power generation charging / discharging devices (30-33) increases. Therefore, although all surplus power from solar power generation can be utilized and both the solar power generation amount and the storage battery capacity can be expanded with high efficiency, wiring costs and installation costs are still required. In the solar power generation storage system (83) of the fifth embodiment, the solar power generation device (100) consisting of a solar string is wired, and the inputs of the solar power generation charge / discharge devices (30 to 33) are also wired, with two positive and negative poles connecting between them. Therefore, in the solar power generation storage system (83) of the fifth embodiment, the number of power lines can be significantly reduced, enabling further cost reduction.

[0078] In the solar power generation power storage system (83) of the fifth embodiment, the 2.7 kW solar power generation circuits of the solar power generation device (100) are connected together, and the MPPT chargers (CH31-1 to CH31-4) of the solar power generation charging / discharging devices (30 to 33) are connected in parallel. That is, this embodiment is a power storage system in which the number of power lines wired to the inputs of the solar power generation charging / discharging devices (30 to 33) is reduced. In addition, in the solar power generation power storage system (83) of the fifth embodiment, the output terminals, which are DC connection terminals (T33-1 to T33-4) of the solar power generation charging / discharging devices (30 to 33), are connected to the same DC bus line (70) and are connected to a backflow prevention diode (D51) and a DC / AC inverter (40) of the external power supply (50), and the solar power generation charging / discharging devices (30 to 33) are connected to each other by communication lines and controlled in synchronous operation. Furthermore, in this embodiment, the communication line is connected to a computer (60), for example, a PC (personal computer), for setting charging control conditions and discharging control for the MPPT chargers (CH31-1 to CH31-4).

[0079] The solar power storage system (83) of the fifth embodiment reduces the number of wires between the solar power generation device (100) and the solar power generation charging / discharging devices (30-33) compared to the solar power generation storage system (82) of the fourth embodiment, thereby enabling further reduction in the cost of wire materials and installation costs (installation costs, etc.). In the solar power generation storage system (82) of the fourth embodiment, the solar power generation device (100) and the solar power generation charging / discharging devices (30-33) require eight wires (two poles, + / -, x four circuits), whereas in the solar power generation storage system (83) of the fifth embodiment, the solar power generation device (100) and the solar power generation charging / discharging devices (30-33) can be connected with two wires (two poles, + / -, x two circuits), thereby minimizing the number of power lines.

[0080] In the solar power generation storage system (83) of the fifth embodiment, the four circuits of the solar power generation device (100) are wired together into one, and from there to the solar power generation charging / discharging devices (30 to 33) are connected with two cables, a positive pole and a negative pole, and the input terminals, which are the solar panel connection terminals (T31-1 to T31-4) of the solar power generation charging / discharging devices, are connected in parallel, thereby minimizing the wiring cables.

[0081] In the solar power generation power storage system (83) of the fifth embodiment, the power generation amount (P100) of the solar power generation device (100) is equal to P30+P31+P32+P33, and the MPPT charger performs synchronous operation control (MPPT control) at the maximum power point (P100) of the solar power generation device (100).

[0082] The solar power generation energy storage system of Example 5 of the present invention does not have a commercial power source within the solar power generation charging / discharging device, and is highly efficient as it can utilize all surplus power from solar power generation. Furthermore, it is possible to expand the amount of solar power generation and the storage battery capacity, and it is possible to reduce the number of wirings, and it is also possible to reduce the material costs of the wiring and the installation costs.

[0083] Example 6 Fig. 11 is a diagram showing the configuration of a solar power generation electricity storage system according to a sixth embodiment of the present invention. In the solar power generation electricity storage system (84) of the sixth embodiment, control circuits (CU31-1 to CU31-4) perform synchronous operation in which one of the solar power generation charging / discharging devices (30 to 33) for charging / discharging is the master solar power generation charging / discharging device (CH31-1 in the example of Fig. 11) and the other solar power generation charging / discharging devices (CH31-2 to 4 in the example of Fig. 11) are slaves, detect the total input power and total output power to all the solar power generation charging / discharging devices (30 to 33), and vary the maximum charging current values ​​for all MPPT chargers (CH31-1 to 4) so ​​that the total input power is greater than the total output power.

[0084] In the solar power generation electricity storage system (82) of the fifth embodiment and the solar power generation electricity storage system (83) of the sixth embodiment, the output of the solar power generation device (100) and the input of the solar power generation charge / discharge devices (30-33) are connected to the same DC-BUS line (70). If the maximum power point control method of each MPPT charger of multiple solar power generation charging / discharging devices is controlled individually, depending on the amount of power generated by the solar power generation device, i.e., when the amount of solar power generation (P100) falls below the input power (P30+P31+P32+P33) of the solar power generation charging / discharging device, there is a risk that the MPPT chargers will compete for power, resulting in unbalanced charging and uneven charging rates of the storage batteries, resulting in a power imbalance operating state, which may cause a decrease in the solar power generation tracking efficiency (tracking efficiency of approximately 50%) in maximum power point control (MPPT control), and may prevent highly efficient power conversion that effectively tracks unstable fluctuations in solar power generation. However, the solar power generation storage system (83) of Example 6 minimizes such power imbalance operation as follows.

[0085] In the solar power generation power storage system (83) of Example 6, a plurality of solar power generation charging / discharging devices (30-33) are connected by communication lines, one of a plurality of MPPT chargers (CH31-1 to 4) serves as a master, and the others serve as slaves, with the same maximum charging current and maximum charging voltage settings, and maximum power point control (MPPT control) is performed by the other MPPT chargers (CH31-2 to 4 in the example of FIG. 11) in synchronization with the master MPPT charger (CH31-1 in the example of FIG. 11). That is, in this example, the MPPT control of the master and the charging control settings for the storage battery (such as the maximum charging current and maximum constant charging voltage) are operated synchronously with the same settings.

[0086] In this embodiment, when the amount of solar power generation (P100) falls below the input power (P30+P31+P32+P33) of the solar power generation charging / discharging devices (30-33), the input power (P30+P31+P32+P33) is controlled to be less than the amount of solar power generation (P100). This can minimize the occurrence of power competition among the MPPT chargers, resulting in unbalanced charging and an operating state with unbalanced power.

[0087] A voltage comparison is performed between the voltage PVV of the solar power generation device (100) and the output voltage DCV of the solar power generation charging / discharging devices (30 to 33), and control is performed to adjust the maximum charging current (Icc) of the MPPT chargers (CH31-1 to 4) of the solar power generation charging / discharging devices (30 to 33) so that "solar voltage PVV>output voltage DCV of the solar power generation charging / discharging devices."

[0088] In this embodiment, synchronous operation is controlled by CAN communication (Controller Area Network communication) between the master and slave. Any device that does not receive CAN communication will stop operating.

[0089] Electric power (P100) from the solar power generation device (100) is input to the MPPT chargers (CH31-1 to CH31-4) of the solar power generation charging / discharging devices (30 to 33), and the solar power generation charging / discharging devices (30 to 33) are connected to each other by communication lines, and the MPPT chargers (CH31-1 to CH31-4) perform maximum power point control (MPPT control) for solar power generation, and perform synchronous operation with the same set values ​​for maximum charging current value and maximum charging constant voltage value. Various set values ​​are set by communication from a computer (60) such as a PC.

[0090] FIG. 12 is an explanatory diagram of synchronous operation and charging control of MPPT chargers in a solar power generation power storage system according to a sixth embodiment of the present invention. The synchronous operation method and MPPT charging method of the MPPT chargers in the solar power generation power storage system according to the sixth embodiment are control methods relating to synchronous operation of MPPT chargers (CH31-1 to 4) of multiple solar power generation charging / discharging devices (30 to 33) connected in parallel to the same DC-BUS line of the solar power generation system. FIG. 12 shows an example of charging control of the MPPT chargers (CH31-1 to 4). As described above, in this embodiment, power from the solar power generation device (100) is input to the MPPT chargers (CH31-1 to 4) of the solar power generation charging / discharging devices (30 to 33). In this embodiment, the voltage (PVV) of the solar power generation device (100) and the DC output voltage (DCV) of the solar power generation charge / discharge devices (30-33) are detected during synchronous operation of maximum power point control (MPPT control) of solar power generation, and the maximum charging current value (Icc) is varied so that PVV is greater than DCV. This variable control can significantly improve the solar power generation power tracking efficiency (tracking efficiency > 91%).

[0091] FIG. 13 shows an example of a flow chart of a control method in a solar power generation electricity storage system according to a sixth embodiment of the present invention, in which the PVV voltage is compared with the DCV voltage and the maximum constant charging current value is variably controlled.

[0092] The continuous detection timer for voltage value comparison is set, for example, to timer T1 = 3 min and judgment time T2 = 2 sec. Icc (maximum constant charging current) is set, for example, to Imax = 14 A, Imid = 7 A, and Imin = 3 A. The continuous detection timer value and maximum charging current values ​​Imax, Imid, and Imin can be set on a PC, and there is no limit to the number of variables for the maximum charging current value. Note that it is preferable to increase the number of current value steps and provide finer current changes to perform near-linear control. This allows the amount of charging energy to be optimized. In addition, this embodiment will be described using an example of four MPPT chargers, CH31-1 to CH31-4, operating synchronously, but there is no limit to the number of units, as long as it is more than two.

[0093] {charging} An example of charging control for the MPPT charger (CH31-1 to 4) is the following four steps.

[0094] (Step 1) First, in controlling the MPPT chargers (CH31-1 to CH31-4) of multiple photovoltaic power generation charging / discharging devices (30 to 33), one is selected as the master and the others as slaves. By measuring the voltages of all photovoltaic power generation charging / discharging devices in order, the MPPT charger with the lowest battery voltage is detected and selected as the master. The storage battery connected to the MPPT charger of the photovoltaic power generation charging / discharging device with the lowest battery voltage is given priority for charging, thereby controlling constant current charging for the longest time. As described below, in this embodiment, power control is performed on the slave side using the same output setting value (constant voltage / constant current) as the master. The control program installed in the controlling PC stores the number of the photovoltaic power generation charging / discharging device to be designated as the master in the PC's memory. For example, if Batt. No. 3 has the lowest power, "3" is entered into "X" in Figure 13, and the photovoltaic power generation charging / discharging device of Batt. No. 3 becomes the "Master."

[0095] (Step 2) Each MPPT charger controlled by a PC transmits the power control value of the MPPT control tracking value (maximum power point) detected by the master to the slave MPPT charger, and operates in sync with the master MPPT charger. This allows charging to make the most of the solar power generated.

[0096] (Step 3) Charging is performed by setting the Icc (charging current value), and the Icc can be changed and set in three stages depending on the relationship between the PV input voltage (PVV) and the DC output voltage (DCV).

[0097] (Step 3-1) First, the charging current value (Icc) is set to Imin (for example, 3A).

[0098] Initially, timer T1 is not set, and the PV input voltage (PVV) and DC output voltage (DCV) are immediately detected and compared. If "PVV > DCV" continues for a determination time T2 (for example, 2 seconds), proceed to step 3-2 without setting T1.

[0099] If the detection results of the PV input voltage (PVV) and DC output voltage (DCV) do not remain "PVV > DCV" for a continuous period of time T2, i.e., if "PVV ≦ DCV" is detected even once during T2, the process returns to step 1 while continuing charging at Imin. If "PVV > DCV" does not remain continuously for a continuous period of time T2, steps 1 to 3-1 are repeated. In other words, the master and all slave MPPT chargers continue to charge at the minimum charging current value Imin. If the voltage of the other storage battery becomes lower, the master is changed at step 1 after returning to step 1.

[0100] If returning to step 3-1 after step 3-2, timer T1 is set to 3 minutes, so after charging at Imin for T1 (for example, 3 minutes at 3A) using the master and all slave MPPT chargers, the PV input voltage (PVV) and DC output voltage (DCV) are detected and compared. If "PVV > DCV" is maintained continuously for the determination time T2 (for example, 2 seconds), the process proceeds to step 3-2 with T1 set. If "PVV > DCV" is not maintained continuously for T2, that is, if "PVV ≦ DCV" is detected even once during T2, timer T1 is set to 3 minutes and the process returns to step 3-1 again.

[0101] (Step 3-2) Set the charging current value (Icc) to the Imid value (for example, 7A).

[0102] If T1 is not set, the PV input voltage (PVV) and DC output voltage (DCV) are immediately detected and compared. If "PVV > DCV" is maintained continuously for a determination time T2 (for example, 2 seconds), proceed to step 3-3 without setting T1.

[0103] If the detection results of the PV input voltage (PVV) and DC output voltage (DCV) do not become "PVV > DCV" continuously for T2, that is, if "PVV ≦ DCV" is detected even once during T2, set T1 (for example, 3 minutes) and return to step 3-1.

[0104] If you return to step 3-1 after step 3-2 and proceed to step 3-2, or if you return to step 3-2 after step 3-3, timer T1 is set to 3 minutes, so after charging at Imid for T1 (for example, 3 minutes at 7A) using the master and all slave MPPT chargers, the PV input voltage (PVV) and DC output voltage (DCV) are detected and compared. If PVV > DCV is maintained continuously for the determination time T2 (for example, 2 seconds), proceed to step 3-3 with T1 set. If PVV > DCV is not maintained continuously for T2, that is, if PVV <= DCV is detected even once during T2, the timer is set to T1 = 3 minutes and return to step 3-1.

[0105] (Step 3-3) The charging current value (Icc) is set to the Imax value (for example, 14A).

[0106] If T1 is not set, the PV input voltage (PVV) and DC output voltage (DCV) are immediately detected and compared. If PVV > DCV continues for a determination time T2 (for example, 2 seconds), set T1 and repeat step 3-3.

[0107] If the detection results of the PV input voltage (PVV) and DC output voltage (DCV) do not continuously satisfy "PVV > DCV" for T2, that is, if "PVV ≦ DCV" is detected even once during T2, the timer is set to T1 = 3 minutes and the process returns to step 3-2.

[0108] If you return to step 3-2 after step 3-3 and proceed up to step 3-3, or if you return to step 3-3 again after step 3-3, timer T1 is set to 3 minutes, so after charging at Imax for T1 (for example, 3 minutes at 14A) using the master and all slave MPPT chargers, the PV input voltage (PVV) and DC output voltage (DCV) are detected and compared. If PVV > DCV is maintained for a continuous period of time T2 (for example, 2 seconds), step 3-3 is repeated with T1 set. If PVV > DCV is not maintained for a continuous period of time T2, that is, if PVV <= DCV is detected even once during T2, the timer is set to T1 = 3 minutes and the process returns to step 3-2.

[0109] According to the solar power generation energy storage system of Example 6 of the present invention, the problem of reduced solar power generation tracking efficiency due to power imbalance operation of an MPPT charger connected in parallel to the same DC bus line of a solar power generation system can be significantly improved (from about 50% to 91% or more) by variably controlling the charging power of the MPPT charger to always ensure that the solar power generation voltage (PVV voltage) is greater than the output voltage (DCV voltage) of the solar power generation charging / discharging device. According to this example, the tracking efficiency of the MPPT chargers can be maximized even when charging in parallel.

[0110] In order to maximize the solar power generation tracking efficiency of the MPPT charger connected in parallel, in this embodiment, the charging current is reduced and the charging power of the solar power generation charging / discharging device is lowered so that the solar power generation voltage (PVV voltage) is greater than the output voltage (DCV voltage) of the solar power generation charging / discharging device, thereby controlling so that the PVV voltage is greater than the DCV voltage.

[0111] {discharge} Regarding discharge from the storage battery, the PVV and DCV are monitored and optimal discharge control is used to discharge only the amount of power that is insufficient from solar power generation. This prevents unnecessary discharge and also optimizes the lifespan of the storage battery. When the DCV is less than the power required by the load (for example, 2kW), the storage battery is discharged from an external power source without being controlled by a PC, taking into account the voltage balance and efficiency of the storage battery.

[0112] Furthermore, by connecting a solar power generation charging / discharging device (including storage battery connection) that can make the most of the power generated by solar power generation, DC / AC conversion is performed using a DC / AC inverter to output AC power to an independent power source, and even if solar power generation stops and the capacity of the storage battery decreases, an external power source, which is an AC / DC power source that utilizes commercial power or external power from a generator, can be used as the input power for the DC / AC inverter.In addition, each of these power utilizations enables linear power conversion using diode connections in the order of solar power generation power > storage battery power > external power source, realizing a solar storage independent power source system that can supply stable AC power with a simple control circuit that does not require a power switching circuit.

[0113] According to the solar power generation storage system of Example 6 of the present invention, there is no commercial power source within the solar power generation charging / discharging device, and all surplus power from solar power generation can be utilized, making it highly efficient. Furthermore, it is possible to expand the amount of solar power generation and the storage battery capacity, and it is possible to reduce the amount of wiring, i.e., to minimize the number of power lines installed, and to reduce the material costs and installation costs of the wiring. Furthermore, it is possible to reduce voltage changes even in facilities with large power generation, allowing for a stable power supply, and it is also possible to select the capacity of each storage battery so as to use up environmental energy.

[0114] In this embodiment, the maximum charging current value of the MPPT charger is automatically controlled. However, when the control circuit performs synchronous operation with one of the photovoltaic power generation charging / discharging devices as the master photovoltaic power generation charging / discharging device and the other photovoltaic power generation charging / discharging devices as slaves, the maximum charging current value may be fixed instead of the automatic control described above depending on the local sunlight conditions. The photovoltaic power generation charging / discharging device may also be provided with a switch to select three or more fixed values ​​(e.g., 3 A, 7 A, 14 A) for the maximum charging current value of the MPPT charger. Furthermore, the switch may be used to select between three or more fixed values ​​(e.g., 3 A, 7 A, 14 A) and automatic control. In locations where the amount of photovoltaic power generation is large and PVV > DCV can be achieved with just a fixed setting without varying the maximum charging current value, a fixed maximum charging current value can be used, allowing for simple setting according to local conditions.

[0115] In any of the photovoltaic power generation charging / discharging devices of Example 1 and Examples 2 to 6, renewable energy can be used preferentially and outdoors in cold climates. Furthermore, this example uses Japanese-made lithium-ion batteries with excellent low-temperature characteristics, making it suitable for outdoor use in colder climates. According to this example, no power conversion loss occurs due to the bidirectional DC / DC power supply, and efficiency does not decrease. Furthermore, the circuit configuration is simple and failures are unlikely to occur. A stable supply of power is possible without the need for operation switching. Surplus power can be stored in a storage battery, making it possible to effectively utilize renewable energy regardless of the status of power generation and transmission volume on the grid side.

[0116] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. [Explanation of symbols]

[0117] 10, 100 Solar power generation equipment D10, D11 reverse current prevention diodes 20, 21, 22, 23 Storage battery 30, 31, 32, 33 Solar power generation charging and discharging device CH31, CH31-1~4 MPPT charger CU31 control circuit D31 Bypass diode D32 Reverse current prevention diode T31, T31-1~4, T32 solar panel connection terminal T33, T33-1~4, T34 DC connection terminal T35, T36 battery connection terminal S31 Cut-off switch 40 DC / AC inverter 50 External power supply D51 Reverse current prevention diode 60 Computer 70 DC-BUS Line 80, 81, 82, 83 Solar power generation storage system P1 intersection

Claims

1. (A) A solar panel connection terminal connected to a solar panel, a storage battery connection terminal connected to a storage battery, and a DC connection terminal for supplying power to a specific load; an MPPT charger connected to the solar panel connection terminal and controlling the voltage and current output by the solar panel; a cutoff switch and a backflow prevention diode provided between the MPPT charger and the DC connection terminal; a bypass diode provided in a circuit that supplies power directly from the solar panel connection terminal to the DC connection terminal; a control circuit that controls the cutoff switch based on the state of the output of the MPPT charger and the output from the storage battery connection terminal, and controls the amount of power supplied from the storage battery connection terminal to the DC connection terminal and from the solar panel connection terminal to the storage battery connection terminal; and The control circuit When it is detected that the power output from the solar panel connection terminal exceeds a predetermined value, only the power that exceeds the predetermined value is output from the solar panel connection terminal to the storage battery connection terminal; When it is detected that the power output from the solar panel connection terminal falls below a predetermined value, only the power that falls below the predetermined value is output from the storage battery connection terminal to the DC connection terminal. Including a solar power generation charging and discharging device, (B) one or more solar power generation devices are connected to the solar panel connection terminal, and a DC / AC inverter is provided between the DC connection terminal and a specific load; (C) A solar power generation energy storage system, wherein an external power supply is provided between the DC connection terminal and the DC / AC inverter, and when the control circuit detects that the power output from the DC connection terminal falls below a predetermined value, the external power supply outputs only the power by which the power falls below the predetermined value to the DC / AC inverter, (D) A solar power generation storage system including a plurality of the solar power generation charging / discharging devices, each connected to the external power supply and the DC / AC inverter via a single DC-BUS line from its DC connection terminal.

2. (A) A solar panel connection terminal connected to a solar panel, a storage battery connection terminal connected to a storage battery, and a DC connection terminal for supplying power to a specific load; an MPPT charger connected to the solar panel connection terminal and controlling the voltage and current output by the solar panel; a cutoff switch and a backflow prevention diode provided between the MPPT charger and the DC connection terminal; a bypass diode provided in a circuit that supplies power directly from the solar panel connection terminal to the DC connection terminal; a control circuit that controls the cutoff switch based on the state of the output of the MPPT charger and the output from the storage battery connection terminal, and controls the amount of power supplied from the storage battery connection terminal to the DC connection terminal and from the solar panel connection terminal to the storage battery connection terminal; and The control circuit When it is detected that the power output from the solar panel connection terminal exceeds a predetermined value, only the power that exceeds the predetermined value is output from the solar panel connection terminal to the storage battery connection terminal; When it is detected that the power output from the solar panel connection terminal falls below a predetermined value, only the power that falls below the predetermined value is output from the storage battery connection terminal to the DC connection terminal. Including a solar power generation charging and discharging device, (B) one or more solar power generation devices are connected to the solar panel connection terminal, and a DC / AC inverter is provided between the DC connection terminal and a specific load; (C) A solar power generation energy storage system, wherein an external power supply is provided between the DC connection terminal and the DC / AC inverter, and when the control circuit detects that the power output from the DC connection terminal falls below a predetermined value, the external power supply outputs only the power by which the power falls below the predetermined value to the DC / AC inverter, (E) A solar power generation energy storage system characterized in that the wiring connected to a plurality of solar power generation devices is combined into a single wiring, and the wiring is redistributed and connected to the solar panel connection terminals of each of the solar power generation charging / discharging devices, which are connected in parallel, and the control circuits of all the solar power generation charging / discharging devices are collectively controlled and communicated with, and each DC connection terminal is connected to the external power source and the DC / AC inverter via a single DC-BUS line.

3. 3. The solar power generation energy storage system according to claim 2, wherein the control circuit performs synchronous operation with one of the solar power generation charging / discharging devices as a master solar power generation charging / discharging device and the other solar power generation charging / discharging devices as slaves, and is provided with a changeover switch for changing over three or more fixed values ​​for the maximum charging current value of the MPPT charger.

4. A control method for a solar power generation storage system as described in claim 2, characterized in that the control circuit performs synchronous operation of the solar power generation charging / discharging devices, with one of the solar power generation charging / discharging devices being a master solar power generation charging / discharging device and the other solar power generation charging / discharging devices being slaves, detects the total input power and total output power to all of the solar power generation charging / discharging devices, and varies the maximum charging current value for all of the MPPT chargers so that the total input power is greater than the total output power.

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