JP2023055882A - Storage battery-added photovoltaic power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage battery-added photovoltaic power generation system that can suppress potential induced degradation of a PV module using a switch of an electrification adjustment circuit provided between the PV module and a power conditioner and can prevent a contact point of the switch from being worn.

SOLUTION: A storage battery-added photovoltaic power generation system comprises: a storage battery 3 for storing power from a PV module 2 or a system power supply 15; and an electrification adjustment circuit 4 that is provided, between the PV module 2 and a power conditioner 5, on main electric paths La, Lb through which positive current flows when the PV module 2 is generating power and negative current flows when the PV module is generating no power. The electrification adjustment circuit 4 has a parallel circuit 6 on at least one of the main electric paths La, Lb, a switch 7 provided on one of the electric paths in the parallel circuit 6, and a diode 8 provided on the other of the electric paths, the diode 8 disposed so as to have a forward direction in which the negative current flows.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a storage-battery-equipped photovoltaic power generation system that includes a solar cell module and a storage battery that stores electric power from the solar cell module or a system power supply, and that suppresses a phenomenon in which the output of the solar cell module decreases.

2. Description of the Related Art Conventionally, a solar power generation system with a storage battery that makes effective use of a storage battery has been known. In this system, it is necessary to suppress PID (Potential Induced Degradation: performance deterioration phenomenon) in which the solar cell module deteriorates and the amount of power generated by the solar cell module deteriorates.

In the PID of this solar cell module, the potential difference between the protective glass substrate and the photoelectric conversion cells causes ions to diffuse from the glass substrate into the sealing material and move to the photoelectric conversion cells, resulting in performance degradation.

As a device for suppressing the above-mentioned performance deterioration phenomenon, based on the knowledge that the performance deterioration is caused by the application of high voltage from the power conditioner to the solar battery module when the solar battery module is not generating power, the solar battery module and the storage battery It is known to prevent the voltage from the inverter from being applied to the solar cell module by interrupting the electrical connection with the solar cell module (for example, Patent Document 1).

A conventional photovoltaic power generation system 51 shown in FIG. and a power conditioner 55 including an inverter 61 that converts the DC power from the solar cell module 52 and the storage battery 53 into AC power. The electrical connection between the solar module 52 and the storage battery 53 is switched 70 to prevent the high voltage from the inverter 61 from being applied to the solar module 52 that is not generating power, such as at night. shut off by This prevents the high voltage from the inverter 61 from being applied to the solar cell module 52 when the solar cell module 52 is not generating power, thereby suppressing the deterioration of its performance.

Japanese Patent No. 6148782

However, when the switch 70 is switched from when the solar cell module 52 is generating power (mainly during the daytime) to when it is not generating power (mainly during the nighttime), the moment the switch is turned on (closed) to off (open), An excessive voltage develops across switch 60 because the current is interrupted.

In this case, the contact of the switch 70 may be worn out due to excessive voltage when the switch is opened and closed, shortening the life of the switch 70 .

The present invention can suppress deterioration of the performance of the solar cell module by using the switch of the energization adjustment circuit provided between the solar cell module and the power conditioner, and can prevent wear of the contact of the switch. It is an object of the present invention to provide a photovoltaic power generation system with a storage battery that can

In order to achieve the above object, a solar power generation system with a storage battery according to the present invention comprises a solar cell module, a storage battery for storing electric power from the solar cell module or a system power supply, and an electric a power conditioner that is physically connected to convert DC power generated by the solar cell module; an energization adjustment circuit provided in a main electric circuit through which a current flows and a negative current flows when not generating power,
The energization adjusting circuit has a parallel circuit provided in at least one of the main electric paths, a switch provided in one electric path of the parallel circuit, and a diode provided in the other electric path, and the diode is connected in the forward direction. are arranged in the direction in which the negative current flows.

According to this configuration, a positive current flows from the solar cell module to the power conditioner when the solar cell module is generating power. Although the switch cuts off one electric path of the parallel circuit when no power is being generated, a negative current flows through the diode in the other electric path of the parallel circuit, and the solar cell module and the storage battery are always in an electrified state. A predetermined voltage that is lowered by a forward voltage drop of a diode is applied to the battery module. This reduced voltage is set to suppress deterioration of the solar cell module. That is, the PID (performance deterioration phenomenon) of the solar cell module PV can be suppressed to a certain extent by utilizing the forward voltage drop in the diode. In this case, it is possible to use the electric power of a storage battery that stores cheap late-night electric power for energization.

In the present invention, further comprising detecting means for detecting whether or not the solar cell module is generating power, the switch is turned on when the solar cell module is generating power to generate a positive current through one of the parallel circuits. , the switch is turned off when no power is being generated, and a negative current flows through the other electric path of the parallel circuit with the forward voltage dropped by the diode. In this case, the PID (performance deterioration phenomenon) of the solar cell module can be suppressed to a certain extent by easily utilizing the forward voltage drop in the diode.

Also, in the present invention, it is preferable that an overvoltage is generated in the switch when the switch is switched from on to off, and this is applied to the diode in the reverse direction to suppress the overvoltage to the reverse breakdown voltage.

According to this configuration, even if an excessive voltage occurs across the switch, the excessive voltage is applied as a reverse bias to the diode in the parallel circuit. For excessive voltage, the diode breaks down and reverse current flows. As the diode breaks down, the excessive voltage is suppressed to the reverse breakdown voltage of the diode, so that wear of the switch contacts can be prevented and the life of the switch can be lengthened.

Preferably, the energization adjustment circuit may further include a fuse in series with the diode in the parallel circuit. In this case, even if the diode fails and a high voltage is applied, the fuse cuts off the high voltage, so PID (performance deterioration phenomenon) of the solar cell module can be suppressed more safely.

In the present invention, an energization adjustment circuit having a parallel circuit of a switch and a diode is provided between the solar cell module and the power conditioner, and the forward voltage drop across the diode is utilized when the solar cell module is not generating power. Therefore, the PID (performance deterioration phenomenon) of the solar cell module can be suppressed to a certain extent. In addition, the life of the switch can be lengthened by preventing wear of the contact of the switch.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the photovoltaic power generation system with a storage battery which concerns on one Embodiment of this invention. It is a circuit diagram which shows the outline of the photovoltaic power generation system with a storage battery of FIG. (A) and (B) are circuit diagrams showing the operation of the photovoltaic power generation system with storage battery of the present invention. FIG. 2 is a circuit diagram showing the operation of the photovoltaic power generation system with a storage battery of the present invention; FIG. 3 is a circuit diagram showing another example of the photovoltaic power generation system with a storage battery according to the present invention; It is a circuit diagram which shows the conventional photovoltaic power generation system with a storage battery.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a photovoltaic power generation system 1 with a storage battery according to one embodiment of the present invention. This photovoltaic power generation system 1 includes a photovoltaic module (PV) 2, a storage battery 3, an energization adjustment circuit 4, and a power conditioner 5. The storage battery 3 is effectively used to suppress performance deterioration of the photovoltaic module 2. It is a plan.

FIG. 2 is a circuit diagram showing an outline of the photovoltaic power generation system 1 with a storage battery in FIG. The storage battery-equipped photovoltaic power generation system 1 of FIG. The DC power generated by the connected solar cell module 2 is converted into AC power (inverter 11) and supplied to the system power supply 15, and converted into DC power (DC/DC converter not shown) to be supplied to the storage battery. 3 and a power conditioner 5 that feeds the In the main electric lines La and Lb between the solar cell module 2 and the power conditioner 5, a positive current flows when the solar cell module 1 is generating power (mainly during the daytime), and a positive current flows when the solar cell module 1 is not generating power (mainly during the night). ) a negative current flows.

The main electric lines La and Lb are provided with an energization adjustment circuit 4. The energization adjustment circuit 4 is provided with, for example, parallel circuits 6a and 6b for each of the main electric lines La and Lb. are provided with switches 7a and 7b, and the other electric path is provided with diodes 8a and 8b.

The diodes 8a and 8b are arranged with the forward direction being the direction in which the negative current flows in the main electrical paths La and Lb when the solar cell module 2 is not generating power. That is, the diode 8a of the main electric line La has its cathode (K) connected to the solar cell module 2 side and the anode (A) connected to the power conditioner 5 side, and the diode 8b of the main electric line Lb has its anode (A) connected to the sun. It is connected to the battery module 2 side, and the cathode (K) is connected to the power conditioner 5 side. Fuses 9a and 9b are provided in series with the diodes 8a and 8b, respectively.

A detecting means 12 is further provided for detecting whether or not the solar cell module 2 is generating power, for example, by its output voltage. A control circuit 10 is also provided for performing ON/OFF control of the switches 7a and 7b according to the power generation state of the solar cell module 2 and for controlling the entire system. The DC power of the storage battery 3 is converted into AC power by the inverter 11 and supplied to the system power supply 15 and the load 13 .

When the solar cell module 2 is generating power, the switches 7a and 7b are turned on and a positive current flows. flows.

As shown in FIG. 3A, when the solar cell module 2 is generating electricity (mainly in the daytime), the switch 7a of the main electric line La and the switch 7b of the main electric line Lb are turned on (closed), and the main electric line La is turned on (closed). A positive current PA flows from the battery module 2 to the power conditioner 5 and from the power conditioner 5 to the solar cell module 2 in the main electric line Lb. Thereby, the DC power generated by the solar cell module 2 is supplied to the power conditioner 5 .

As shown in FIG. 3B, when the solar cell module 2 is not generating power (mainly at night), the switches 7a and 7b are turned off (opened), and the power conditioner 5 is connected to the solar cell module 2 in the main electric line La. , a negative current NA flows from the solar cell module 2 to the power conditioner 5 through the diodes 8a and 8b in the main electric line Lb. As a result, a voltage forward-dropped by the diodes 8 a and 8 b is applied to the solar cell module 2 .

Thus, when the solar cell module 2 is not generating electricity, the switch 7a cuts off one of the electric paths of the parallel circuit 6a, while the other electric path of the parallel circuit 6a is energized by the diode 8a. Moreover, although the switch 7b cuts off one of the electric paths of the parallel circuit 6b, the other electric path of the parallel circuit 6b is energized by the diode 8b, so that the solar cell module 2 and the storage battery 3 are always energized. A predetermined voltage is applied to the solar cell module 2, the voltage being lowered by the forward voltage drop of the diodes 8a and 8b.

This lowered voltage is set to a value that can suppress performance deterioration of the solar cell module 2 . That is, PID (performance deterioration phenomenon) of the solar cell module 2 can be suppressed to a certain extent by utilizing the forward voltage drop in the diodes 8a and 8b. In this respect, it differs from the conventional technology in which the main electric circuit between the solar cell module and the power conditioner is simply cut off. In this case, it is possible not only to supply the electric power of the storage battery 3 storing inexpensive late-night electric power to the load 13, but also to use it for energizing the forward voltage drop.

In addition, by providing fuses 9a and 9b in series with diodes 8a and 8b in parallel circuits 6a and 6b, even if diodes 8a and 8b fail and a high voltage is applied, the fuses 9a and 9b will shut off the voltage, making it safer. PID (performance deterioration phenomenon) of the solar cell module can be suppressed. This has the effect of enhancing safety not found in the prior art.

As shown in FIGS. 3A and 3B, when the switches 7a and 7b are switched from on to off, an excessive voltage is generated in the switches 7a and 7b, which is applied to the diodes 8a and 8b in the reverse direction, The excessive voltage is suppressed to the reverse breakdown voltage.

As shown in FIG. 4, when the switches 7a and 7b are switched from when the solar cell module 2 is generating power (mainly during the day) to when it is not generating power (mainly at night), the switch is switched on (closed) to off. Since the current is interrupted at the moment of (open), an excessive voltage is generated across the switches 7a and 7b. In that case, an overvoltage is applied as a reverse bias to the diodes 8a, 8b of the parallel circuits 6a, 6b. Diodes 8a, 8b break down in response to excessive voltages and reverse current flows. As the diodes 8a and 8b break down, the excessive voltage is suppressed to the reverse breakdown voltage of the diodes 8a and 8b.

As described above, the contacts of the switches 7a and 7b may be worn out due to excessive voltage when the switches are opened and closed, shortening the life of the switches 7a and 7b. Therefore, it has the effect of preventing wear of the contacts of the switches 7a and 7b and prolonging their life. This makes it possible to solve the problems of the prior art.
When the overvoltage disappears, the state shown in FIGS. 3A and 3B is restored.

FIG. 5 shows another example of a photovoltaic power generation system 1A with a storage battery. In this other example, unlike FIG. 1 in which parallel circuits 6a and 6b are provided for both main electric lines La and Lb, respectively, parallel circuit 6 is provided only for main electric line La. A switch 7 is provided on one electric path of the parallel circuit 6, and a diode 8 and a fuse 9 are provided on the other electric path. Note that the parallel circuit 6 may be provided only in the main electric line Lb. Other configurations are the same as those in FIG.

In this case as well, when the solar cell module 2 is not generating power, the forward voltage drop in the diode 8 can be used to suppress the PID (performance deterioration phenomenon) of the solar cell module 2 to a certain extent.

In each of the above embodiments, the detection means 12 for detecting the output voltage of the solar cell module 2 is used in order to detect whether or not the solar cell module 2 is generating power. The amount of sunlight irradiation may be detected, or the time period during which sufficient power generation is performed may be measured.

When detecting the irradiation amount of the sunlight, for example, an illuminance sensor may be used to detect the period during which the sunlight is irradiated. Moreover, when measuring the time zone in which sufficient power generation is performed, for example, a timer may be used to measure the time zone in which power generation is performed according to the season.

The present invention is not limited to the above embodiments, and various additions, changes, or deletions are possible without departing from the scope of the present invention. Accordingly, such are also included within the scope of this invention.

1, 1A: Photovoltaic power generation system with storage battery 2: Solar cell module 3: Storage battery 4: Power regulation circuit 5: Power conditioner 6, 6a, 6b: Parallel circuit 7, 7a, 7b: Switch 8, 8a, 8b: Diode 9, 9a, 9b: fuse 10: control unit 11: inverter 12: detection means 13: load 15: system power supply La, Lb: main electric circuit

Claims (4)

A solar cell module, a storage battery for storing power from the solar cell module or a grid power supply, and power electrically connected to the solar cell module and the storage battery for converting DC power generated by the solar cell module. Between the conditioner, the solar cell module, and the power conditioner, a main electric circuit is provided in which a positive current flows when the solar cell module is generating power and a negative current flows when the solar module is not generating power. and an energization adjustment circuit,
The energization adjustment circuit includes a parallel circuit provided in at least one of the main electric paths, a switch provided in one electric path of the parallel circuit, and a diode provided in the other electric path,
The solar power generation system with a storage battery, wherein the forward direction of the diode is arranged in the direction in which the negative current flows. 2. The system according to claim 1, further comprising detecting means for detecting whether the solar cell module is generating power,
When the solar cell module is generating power, the switch is turned on so that a positive current flows through one of the parallel circuits. A photovoltaic system with a storage battery in which a negative current flows through the other side. 3. The photovoltaic power generation with a storage battery according to claim 2, wherein an overvoltage is generated in the switch when the switch is switched from on to off, and this is applied to the diode in the reverse direction to suppress the overvoltage to a reverse breakdown voltage. system. In claim 1,
The photovoltaic power generation system with a storage battery, wherein the energization adjustment circuit is further provided with a fuse in series with the diode in the parallel circuit.

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