Solar power generation system

Abstract

To provide a photovoltaic power generation system capable of achieving both reduction in installation cost of breaker devices and improvement in safety, in a photovoltaic power generation system.SOLUTION: A photovoltaic power generation system comprises a string, an inverter, a first breaker device, and a second breaker device. The string includes a plurality of solar battery module groups connected in series to each other. The first breaker device is connected with a first cable way connecting between the plurality of solar battery module groups. The second breaker device is connected with a second cable way connecting between the plurality of solar battery module groups. The first breaker device disconnects the plurality of solar battery module groups connected with the first cable way from each other depending on a first control signal from the inverter. The second breaker device is connected with the first breaker device so that the bi-directional communication is possible by a communication method different from power line communication, and disconnects the plurality of solar battery module groups connected with the second cable way from each other depending on a second control signal output from the first breaker device.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] In the United States, for the purpose of protecting firefighters from electric shock and the like during emergencies such as fires, the introduction of a so-called rapid shutdown function that immediately stops power generation by a solar power generation system during emergencies is mandated by NEC (National Electrical Code). For example, Patent Document 1 discloses a solar power generation system that stops the output of power from a solar cell module to an inverter according to the operating state of the inverter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a solar power generation system, in order to further improve the safety of firefighters during a fire or the like, for example, it is preferable to install a cutoff device having a rapid shutdown function for each solar cell module. However, when a cutoff device is installed for each solar cell module, the installation cost of the cutoff device becomes high.

[0005] An object of the present invention is to provide a solar power generation system capable of achieving both reduction of the installation cost of a cutoff device and improvement of safety in a solar power generation system.

Means for Solving the Problems

[0006] A photovoltaic power generation system according to one aspect of the present invention comprises a string, an inverter, a first circuit breaker, and a second circuit breaker. The string includes a plurality of solar cell module groups connected in series with each other. Each of the plurality of solar cell module groups includes one or a plurality of solar cell modules connected in series. The inverter is connected to the string and converts the DC power output from the string into AC power. The first circuit breaker is connected to a first circuit that connects the plurality of solar cell module groups together. The second circuit breaker is connected to a second circuit that connects a plurality of solar cell module groups that are different from the plurality of solar cell module groups connected to the first circuit. The open-circuit voltage of each of the plurality of solar cell module groups in the string is less than or equal to a predetermined open-circuit voltage. The first circuit breaker disconnects the connections between the plurality of solar cell module groups connected to the first circuit in response to a first control signal from the inverter. The second circuit breaker is connected to the first circuit breaker in a bidirectional manner using a communication method different from power line communication and disconnects the connections between the plurality of solar cell module groups connected to the second circuit in response to a second control signal output from the first circuit breaker.

[0007] In this solar power generation system, the first and second circuit breakers are in a master-slave relationship. The second circuit breaker disconnects the connections between multiple solar cell module groups in response to the second control signal output from the first circuit breaker. This simplifies the configuration of the second circuit breaker, thereby reducing its installation cost. Furthermore, since the open-circuit voltage of each group of solar cell module is below a predetermined open-circuit voltage, a highly safe solar power generation system can be provided. In addition, the second control signal output from the first circuit breaker is output via a communication line using a communication method different from power line communication, making it less susceptible to noise compared to power line communication and enabling stable communication from the first to the second circuit breaker. Moreover, since the second circuit breaker is connected to the first circuit breaker in a bidirectional communication manner, it becomes possible, for example, to monitor the status of the second circuit breaker from the first circuit breaker.

[0008] The first circuit breaker may monitor the second circuit breaker based on a second status signal output from the second circuit breaker. In this case, the first circuit breaker can monitor whether the second circuit breaker is operating normally.

[0009] The first circuit breaker may output an abnormality signal if it determines that the second circuit breaker is malfunctioning based on the second status signal output from the second circuit breaker. In this case, the first circuit breaker can notify the inverter or the user of the malfunction in the second circuit breaker.

[0010] The first circuit breaker may determine that the second circuit breaker is malfunctioning when it detects that the output of the second status signal from the second circuit breaker has stopped. In this case, it becomes possible to detect the malfunction of the second circuit breaker with a simple configuration.

[0011] The second circuit breaker may be connected to the first circuit breaker via a single wire. In this case, the second circuit breaker can be connected to the first circuit breaker in a simple and inexpensive configuration, enabling bidirectional communication.

[0012] The second circuit breaker may include a switch that opens and closes the connections between multiple groups of solar cell modules connected to the second circuit. The second status signal output from the second circuit breaker may include information regarding the open / closed state of the switch. In this case, for example, the first circuit breaker can monitor whether the switch is operating normally.

[0013] The inverter may monitor the first circuit breaker based on a first status signal output from the first circuit breaker. In this case, the inverter can monitor whether the first circuit breaker is operating normally.

[0014] The inverter may output an abnormality signal if it determines that the first circuit breaker is malfunctioning in response to the first status signal. In this case, the inverter can notify the user or others of the malfunction in the first circuit breaker.

[0015] The first circuit breaker may, in response to a first control signal from the inverter, disconnect the connections between multiple solar cell module groups connected to the first circuit, and then output a second control signal to the second circuit breaker. In this case, the voltage related to the second circuit breaker can be reduced. This makes it possible to reduce the cost of the second circuit breaker.

[0016] Multiple groups of solar cell modules in a string may have an open-circuit voltage of 165V or less per group. In this case, a safer solar power generation system can be provided.

[0017] Multiple groups of solar modules in a string may include a first group. The first circuit breaker may be driven by the power generated by one or multiple solar modules connected in series belonging to the first group. In this case, for example, when installing the first circuit breaker in an existing solar power generation system, additional wiring connecting the inverter and the first circuit breaker can be omitted. This reduces the installation cost of the first circuit breaker. Furthermore, since the driving voltage range of the first circuit breaker can be kept small, the manufacturing cost of the first circuit breaker can be reduced.

[0018] Multiple groups of solar modules in a string may include a second group. The second circuit breaker may be driven by the power generated by one or multiple solar modules connected in series belonging to the second group. In this case, for example, when installing the second circuit breaker in an existing solar power generation system, additional wiring connecting the inverter and the second circuit breaker can be omitted. This reduces the installation cost of the second circuit breaker. Furthermore, since the driving voltage range of the second circuit breaker can be kept small, the manufacturing cost of the second circuit breaker can be reduced.

[0019] The inverter may output a first control signal to the first disconnector by power line communication. In this case, when installing the first disconnector in an existing solar power generation system, additional wiring for ensuring communication between the inverter and the first disconnector can be omitted, so the installation cost of the first disconnector can be suppressed.

[0020] The inverter may output a first control signal to the first disconnector by wireless communication. In this case, it becomes possible to output a first control signal to the first disconnector by remote operation.

[0021] [[ID=X]] At least one of a plurality of solar cell module groups of the string may include a plurality of solar cell modules connected in series. In this case, a plurality of solar cell modules can be disconnected by the first disconnector or the second disconnector.

[0022] The first disconnector may include a bypass diode connected in parallel to any one of a plurality of solar cell module groups. In this case, heat generation etc. of the solar cell module that has become unable to generate power can be suppressed, and a decrease in the power generation efficiency of the string can be suppressed.

[0023] The second disconnector may include a bypass diode connected in parallel to any one of a plurality of solar cell module groups. In this case, heat generation etc. of the solar cell module that has become unable to generate power can be suppressed, and a decrease in the power generation efficiency of the string can be suppressed.

Advantages of the Invention

[0024] According to the present invention, in a solar power generation system, it is possible to provide a solar power generation system that can achieve both reduction of the installation cost of a disconnector and improvement of safety.

Brief Description of the Drawings

[0025] [Figure 1] FIG. 1 is a block diagram schematically showing the configuration of a solar power generation system according to an aspect of the present invention. [Figure 2] FIG. 2 is a block diagram schematically showing the configuration of the first cutoff device. [Figure 3] FIG. 3 is a circuit diagram schematically showing the configuration of the regulator. [Figure 4] FIG. 4 is a block diagram schematically showing the configuration of the second cutoff device. [Figure 5] FIG. 5 is a diagram for explaining an example of the operation mode of the cutoff device. [Figure 6] FIG. 6 is a block diagram schematically showing the configuration of a photovoltaic power generation system according to another embodiment. [Figure 7] FIG. 7 is a block diagram schematically showing the configuration of a photovoltaic power generation system according to another embodiment. [Figure 8] FIG. 8 is a block diagram schematically showing the configuration of a photovoltaic power generation system according to another embodiment. [Figure 9] FIG. 9 is a block diagram schematically showing the configuration of a photovoltaic power generation system according to another embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0026] FIG. 1 is a block diagram schematically showing the configuration of a photovoltaic power generation system 1 according to one aspect of the present invention. The photovoltaic power generation system 1 includes a string 2, an inverter 3, a first cutoff device 4, and a plurality of second cutoff devices 5.

[0027] The string 2 includes a plurality of solar cell module groups 6A to 6H connected in series with each other. The plurality of solar cell module groups 6A to 6H include one or a plurality of solar cell modules 6 connected in series. That is, the string 2 includes a plurality (16 in this embodiment) of solar cell modules 6 connected in series with each other. Note that the photovoltaic power generation system 1 may include a solar cell array in which a plurality of strings 2 are connected in parallel.

[0028] Multiple solar cell module groups 6A to 6H have an open-circuit voltage below a predetermined open-circuit voltage for each group. The predetermined open-circuit voltage is, for example, 165V. That is, string 2 is divided into multiple solar cell module groups such that the open-circuit voltage for each group is 165V or less. The open-circuit voltage of solar cell module 6 is, for example, 50V. Hereafter, solar cell module groups 6A to 6H may be referred to as groups 6A to 6H.

[0029] Each of groups 6A, 6C, 6E, and 6G contains one solar cell module 6. Each of groups 6B, 6D, 6F, and 6H contains three solar cell modules 6 connected in series with each other. Therefore, the open-circuit voltage of groups 6A, 6C, 6E, and 6G is 50V, and the open-circuit voltage of groups 6B, 6D, 6F, and 6H is 150V.

[0030] Groups 6A to 6H are arranged alphabetically from group 6A to group 6H and connected to each other in series. Each of groups 6A to 6H includes an anode terminal and a cathode terminal. The anode terminal of each group 6A to 6H is the anode terminal of the solar cell module 6 belonging to each group 6A to 6H that is closest to the anode of the inverter 3. The cathode terminal of each group 6A to 6H is the cathode terminal of the solar cell module 6 belonging to each group 6A to 6H that is furthest from the anode of the inverter 3.

[0031] For example, the anode terminal of group 6A is connected to the anode terminal of the solar cell module 6 of group 6A. The anode terminal of group 6A is connected to the anode terminal of inverter 3. The anode terminal of group 6A is connected to the cathode terminal of the solar cell module 6 of group 6A. The anode terminal of group 6A is connected to the anode terminal of group 6B.

[0032] For example, the anode terminal of group 6B is connected to the anode terminal of the solar cell module 6 that is closest to group 6A among the solar cell modules 6 belonging to group 6B. The cathode terminal of group 6B is connected to the cathode terminal of the solar cell module 6 that is furthest from group 6A among the solar cell modules 6 belonging to group 6B. The cathode terminal of group 6B is connected to the anode terminal of group 6C.

[0033] The cathode terminal of group 6C is connected to the anode terminal of group 6D. The cathode terminal of group 6D is connected to the anode terminal of group 6E. The cathode terminal of group 6E is connected to the anode terminal of group 6F. The cathode terminal of group 6F is connected to the anode terminal of group 6G. The cathode terminal of group 6G is connected to the anode terminal of group 6H. The cathode terminal of group 6H is connected to the cathode terminal of inverter 3.

[0034] The solar cell module 6 generates electricity from sunlight and outputs the generated electricity to the inverter 3. The inverter 3 is connected to string 2 via power lines. The inverter 3 converts the DC power output from the solar cell modules 6 of string 2 into AC power. The inverter 3 is connected to the power grid 7 and supplies the AC power to the commercial power grid and load devices.

[0035] In detail, the inverter 3 includes a DC / DC converter 3a, a DC / AC inverter 3b, and a control unit 3c. The DC / DC converter 3a converts the voltage of the power output from the solar cell module 6 to a predetermined voltage and inputs it to the DC / AC inverter 3b. The DC / AC inverter 3b converts the DC power output from the solar cell module 6 to AC power via the DC / DC converter 3a. The control unit 3c includes a CPU and memory, and controls the DC / DC converter 3a and the DC / AC inverter 3b. The control unit 3c also outputs a first control signal to the first circuit breaker 4 via power line communication.

[0036] The first circuit breaker 4 is connected to the circuits connecting groups 6A to 6H. In this embodiment, the first circuit breaker 4 is connected to the circuit 8a connecting group 6A and group 6B, and to the circuit 8b connecting inverter 3 and group 6A. The first circuit breaker 4 disconnects the connection between group 6A and group 6B, and the connection between inverter 3 and group 6A, in response to a first control signal from inverter 3.

[0037] The first circuit breaker 4 outputs a second control signal to the multiple second circuit breakers 5 via a communication line 10 connected to the first circuit breaker 4 and the multiple second circuit breakers 5, using a communication method different from power line communication. The first circuit breaker 4 outputs the second control signal to the multiple second circuit breakers 5 using a serial communication method such as LIN (Local Interconnect Network) communication or SPI (Serial Peripheral Interface) communication. The first circuit breaker 4 disconnects the connection between group 6A and group 6B, and the connection between inverter 3 and group 6A, before outputting the second control signal to the multiple second circuit breakers 5. The first circuit breaker 4 is connected to each of the multiple second circuit breakers 5 via the communication line 10.

[0038] The first circuit breaker 4 and the multiple second circuit breakers 5 are in a master-slave relationship. The first circuit breaker 4 functions as the master to the multiple second circuit breakers 5, and the multiple second circuit breakers 5 function as slaves to the first circuit breaker 4. In other words, the first circuit breaker 4 controls the multiple second circuit breakers 5.

[0039] Figure 2 is a schematic block diagram showing the configuration of the first circuit breaker 4. The first circuit breaker 4 includes a regulator 41, a signal receiving unit 42, a control unit 43, a relay 44, and a bypass circuit 45.

[0040] The regulator 41 generates a power supply to drive the first circuit breaker 4 using the power generated by the solar cell module 6, and supplies a stable power supply to the first circuit breaker 4. Here, the power supply for the first circuit breaker 4 is generated using only the power generated by the solar cell module 6 of group 6A.

[0041] Figure 3 is a schematic circuit diagram showing the configuration of regulator 41. The configuration of regulator 41 is a well-known configuration and includes input terminals 21a, 21b, output terminals 22a, 22b, line filter 23, capacitors 24, 25, boost circuit 26, switching element 27, control circuit 28, transformer 29, diode 30, DC / DC converter 31, feedback circuit 32, etc.

[0042] The signal receiving unit 42 receives a first control signal from the control unit 3c of the inverter 3 and outputs the received first control signal to the control unit 43. More specifically, the signal receiving unit 42 receives the first control signal from the control unit 3c of the inverter 3 via a signal detection unit 46 that detects the first control signal from the control unit 3c of the inverter 3.

[0043] The control unit 43 includes a CPU, memory, etc. Based on the signal output from the signal receiving unit 42, the control unit 43 controls the current flowing through the coil of the relay 44 to open and close the contacts of the relay 44. The relay 44 is, for example, a mechanical relay capable of switching high-voltage DC current.

[0044] The control unit 43 outputs a second control signal to a plurality of second circuit breakers 5 via the communication line 10 using a communication method different from power line communication. The control unit 43 outputs the second control signal to the plurality of second circuit breakers 5 after disconnecting the connection between group 6A and group 6B. The control unit 43 determines whether the connection between group 6A and group 6B has been disconnected, for example, by monitoring the voltage between the contacts of the relay 44.

[0045] The relay 44 includes a first switching unit 44a and a second switching unit 44b. The first switching unit 44a is located in the circuit 8b. The first switching unit 44a switches the connection between the inverter 3 and group 6A. The first switching unit 44a is connected to the anode terminal of group 6A and the anode terminal of the inverter 3. The second switching unit 44b is located in the circuit 8a. The second switching unit 44b switches the connection between group 6A and group 6B. The second switching unit 44b is connected to the cathode terminal of group 6A and the anode terminal of group 6B. In this embodiment, the first switching unit 44a may be omitted.

[0046] When the first circuit breaker 4 is not supplied with power from the regulator 41, the first switch 44a and the second switch 44b are always open. Therefore, when the first circuit breaker 4 is not driven, the connection between the inverter 3 and group 6A, and the connection between group 6A and group 6B are disconnected.

[0047] The bypass circuit 45 is a circuit that allows the signal receiving unit 42 to receive the first control signal from the control unit 3c when the first circuit breaker 4 is in the tripped state. When the circuits 8a and 8b are tripped by the first circuit breaker 4, the signal receiving unit 42 can receive the first control signal from the control unit 3c via the bypass circuit 45.

[0048] The multiple second circuit breakers 5 are connected to circuits 8c to 8h that connect groups 6C to 6H, which are different from groups 6A and 6B connected to circuit 8a. The multiple second circuit breakers 5 are connected to the first circuit breaker 4 via a communication line 10, for example, in a serial communication manner, enabling bidirectional communication. The second circuit breakers 5 are connected to the first circuit breaker 4 with a single line. That is, the second circuit breakers 5 are connected to the first circuit breaker 4 with a single communication line 10. The multiple second circuit breakers 5 interrupt the connections between groups 6C to 6H in response to a second control signal output from the first circuit breaker 4 via the communication line 10. In this embodiment, the multiple second circuit breakers 5 include three second circuit breakers 5a to 5c.

[0049] The second circuit breaker 5a is connected to the circuit 8c connecting group 6B and group 6C, and to the circuit 8d connecting group 6C and group 6D. The second circuit breaker 5b is connected to the circuit 8e connecting group 6D and group 6E, and to the circuit 8f connecting group 6E and group 6F. The second circuit breaker 5c is connected to the circuit 8g connecting group 6F and group 6G, and to the circuit 8h connecting group 6G and group 6H.

[0050] Figure 4 is a schematic block diagram showing the configuration of the second circuit breaker 5a. The second circuit breaker 5a includes a regulator 51, a control unit 53, a relay 54, and a bypass circuit 55.

[0051] The regulator 51 generates a drive power supply to drive the second circuit breaker 5a using the power generated by the solar cell module 6, and supplies a stable drive power supply to the second circuit breaker 5a. Here, the drive power supply for the first circuit breaker 4 is generated using only the power generated by the solar cell module 6 of group 6C. The configuration of the regulator 51 is the same as that of the regulator 41 of the first circuit breaker 4, so a detailed explanation is omitted.

[0052] The control unit 53 includes a CPU, memory, etc. The control unit 53 controls the current flowing through the coil of the relay 54 in response to the second control signal from the first circuit breaker 4, thereby controlling the opening and closing of the contacts of the relay 54. The relay 54 is, for example, a mechanical relay capable of switching high-voltage DC current. The relay 54 is an example of a switching unit. The control unit 53 receives the second control signal from the first circuit breaker 4 via a communication interface (not shown) connected to the communication line 10, and opens the contacts of the relay 54. In detail, when the control unit 53 receives the second control signal from the first circuit breaker 4, it outputs a command signal to a relay control unit (not shown) to open the contacts of the relay 54. The relay control unit receives the command signal from the control unit 53 and opens the contacts of the relay 54. The control unit 53 feeds back to the first circuit breaker 4 via the communication line 10 that it has outputted a command signal to the relay control unit to open the contacts of the relay 54.

[0053] Relay 54 includes a third switching unit 54a and a fourth switching unit 54b. The third switching unit 54a is located in the circuit 8c. The third switching unit 54a opens and closes the connection between group 6B and group 6C. The third switching unit 54a is connected to the cathode terminal of group 6B and the anode terminal of group 6C. The fourth switching unit 54b is located in the circuit 8e. The fourth switching unit 54b opens and closes the connection between group 6D and group 6E. The fourth switching unit 54b is connected to the cathode terminal of group 6C and the anode terminal of group 6D.

[0054] When the second circuit breaker 5a is not supplied with power from the regulator 51, the third switch 54a and the fourth switch 54b are always open. Therefore, when the second circuit breaker 5a is not driven, the connection between group 6B and group 6C, and the connection between group 6C and group 6D are disconnected.

[0055] The bypass circuit 55 is a circuit that allows the signal receiving unit 42 of the first circuit breaker 4 to receive the first control signal from the control unit 3c via power line communication when the second circuit breaker 5 is in an interrupted state. By providing the bypass circuit 55, it becomes possible to continue power line communication.

[0056] The relay 54 of the second circuit breaker 5b opens and closes the connection between group 6D and group 6E, and between group 6E and 6F. The relay 54 of the second circuit breaker 5c opens and closes the connection between group 6F and group 6G, and between group 6G and group 6H. The second circuit breakers 5b and 5c have the same configuration as the second circuit breaker 5a, except that the circuits they connect to are different, so a detailed explanation is omitted.

[0057] The first circuit breaker 4 monitors the second circuit breakers 5a to 5c based on the status signals output from the second circuit breakers 5a to 5c. If the first circuit breaker 4 determines that the second circuit breakers 5a to 5c are malfunctioning based on the status signals output from the second circuit breakers 5a to 5c, it outputs a malfunction signal to the inverter 3. When the inverter 3 receives the malfunction signal, the inverter 3 notifies the inverter 3 via the display unit 34 connected to the inverter 3 that the second circuit breakers 5a to 5c are malfunctioning.

[0058] The status signals output from the second circuit breakers 5a to 5c are, for example, feedback to the first circuit breaker 4 in response to the control unit 53 outputting a command signal to the relay control unit after receiving the second control signal. If there is no feedback from the second circuit breakers 5a to 5c, the first circuit breaker 4 determines that the second circuit breakers 5a to 5c are malfunctioning.

[0059] Next, an example of the operating modes of the first circuit breaker 4 and the multiple second circuit breakers 5 will be described with reference to Figure 5. The operating modes of the first circuit breaker 4 and the multiple second circuit breakers 5 include three operating modes: start mode, active mode, and safety mode. The safety mode includes a normal circuit breaker mode and an emergency safety circuit breaker mode. Therefore, the first circuit breaker 4 and the multiple second circuit breakers 5 operate in four operating modes: start mode, active mode, normal circuit breaker mode, and emergency safety circuit breaker mode.

[0060] The start mode is the mode when sunlight begins to hit the solar cell module 6. At this time, the solar cell module 6 generates electricity from the sunlight. The first circuit breaker 4 is then driven by the power supply generated by the regulator 41 from the electricity generated by the solar cell module 6. When the first circuit breaker 4 is driven and the control unit 43 receives the first control signal from the control unit 3c of the inverter 3 via the signal receiving unit 42, the control unit 43 controls the first switching unit 44a and the second switching unit 44b of the relay 44 to close.

[0061] Similarly, the second circuit breaker 5a is driven by a power supply generated by the regulator 51 of the second circuit breaker 5a from the power generated by the solar cell module 6. When the second circuit breaker 5a is driven and the control unit 53 receives a command signal from the first circuit breaker 4 that is different from the second control signal, for example, the control unit 53 controls the third switching section 54a and the fourth switching section 54b of the relay 54 to close. The second circuit breakers 5b and 5c behave similarly to the second circuit breaker 5a. As a result, groups 6A to 6H are connected in string 2 via the first circuit breaker 4 and the second circuit breakers 5a to 5c, and the power generated by the solar cell module 6 is output to the inverter 3.

[0062] The active mode is the state in which the solar cell module 6 generates electricity by receiving sunlight during the day, and is essentially the same as the start mode. Therefore, in the active mode, groups 6A to 6H are connected via the first circuit breaker 4 and the second circuit breakers 5a to 5c, and the power generated by the solar cell module 6 is output to the inverter 3.

[0063] The normal shutdown mode is the mode used when the solar cell module 6 is not receiving sunlight due to nighttime or weather conditions such as rain. Therefore, in the normal shutdown mode, the solar cell module 6 is not generating power, and no power supply is being supplied from the solar cell module 6 to the first shutdown device 4 and the second shutdown devices 5a to 5c. For this reason, in the normal shutdown mode, the first and second switching sections 44a and 44b of the first shutdown device 4, and the third and fourth switching sections 54a and 54b of the second shutdown devices 5a to 5c are all open. In this embodiment, power is supplied to the inverter 3 from an AC power source, and the first control signal is always output from the control unit 3c of the inverter 3, except in the emergency safety shutdown mode.

[0064] In normal shutoff mode, if the power generation of, for example, the solar cell module 6 of group 6A is unstable due to unstable weather conditions, the relay 54 will turn on / off according to the power supplied from the solar cell module 6 of group 6A. Also, if the power generation of, for example, the solar cell module 6 of group 6C is unstable, the relay 54 will turn on / off according to the power supplied from the solar cell module 6 of group 6C.

[0065] The emergency safety shutdown mode is a mode in which the power output from the solar cell module 6 to the inverter 3 is stopped by shutting off the circuits 8a to 8h during the start mode or active mode. In this embodiment, as shown in Figure 1, the operation switch 35 is connected to the inverter 3, and when the operation switch 35 is operated while the first circuit breaker 4 is in the start mode or active mode, the operating mode of the first circuit breaker 4 is switched to the emergency safety shutdown mode.

[0066] In detail, when the operation switch 35 is operated, the control unit 3c stops outputting the first control signal. When the signal detection unit 46 detects that the first control signal has stopped at a certain period of time, the first switching unit 44a and the second switching unit 44b of the relay 44 are opened via the signal receiving unit 42 and the control unit 43. This disconnects the connection between group 6A and group 6B, and the connection between inverter 3 and group 6A, stopping the output of power from the solar cell module 6 to inverter 3. At this time, after opening the first switching unit 44a and the second switching unit 44b of the relay 44, the first disconnector 4 outputs the second control signal to the second disconnectors 5a to 5c via the communication line 10. The second disconnectors 5a to 5c receive the second control signal from the first disconnector 4 and disconnect the connections between groups 6C to 6H. As a result, all groups 6A to 6H are separated from each other, and the open-circuit voltage of string 2 is divided to 165V or less. The control unit 53 of the second circuit breakers 5a to 5c receives a second control signal from the first circuit breaker 4 and feeds back to the first circuit breaker 4 that it has output a command signal to the relay control unit to open the contacts of the relay 54. If the first circuit breaker 4 does not receive feedback from the second circuit breakers 5a to 5c, it determines that the second circuit breakers 5a to 5c are malfunctioning and outputs an abnormality signal to the inverter 3.

[0067] In the solar power generation system 1 with the above configuration, the first circuit breaker 4 and the second circuit breakers 5a to 5c are in a master-slave relationship, and the second circuit breakers 5a to 5c disconnect the connections between multiple solar cell module groups 6B to 6H in accordance with the second control signal output from the first circuit breaker 4. As a result, functions such as the signal receiving unit 42 and the signal detection unit 46 can be omitted in the second circuit breakers 5a to 5c. Consequently, the configuration of the second circuit breakers 5a to 5c can be simplified, and the installation cost of multiple second circuit breakers 5 can be reduced.

[0068] Furthermore, since the open-circuit voltage of each of the multiple solar cell module groups 6A to 6H is 165V or less, a highly safe solar power generation system can be provided. In addition, the second control signal output from the first circuit breaker 4 is output via the communication line 10 using a communication method different from power line communication, so it is less susceptible to noise compared to power line communication, enabling stable communication from the first circuit breaker 4 to the multiple second circuit breakers 5.

[0069] Furthermore, in the above-described photovoltaic power generation system 1, after the connection between group 6A and group 6B is interrupted by the first interruption device 4, the connections between multiple solar cell module groups 6B to 6H are interrupted by the second interruption devices 5a to 5c, thereby reducing the voltage related to the second interruption devices 5a to 5c. This makes it possible to reduce the cost of the second interruption devices 5a to 5c.

[0070] Furthermore, the first circuit breaker 4 is connected to the second circuit breakers 5a to 5c in a bidirectional manner, and monitors the second circuit breakers 5a to 5c based on the status signals output from the second circuit breakers 5a to 5c. As a result, when the operation switch 35 is operated, the first circuit breaker 4 can detect that the second circuit breakers 5a to 5c are operating normally, thus providing a more secure solar power generation system 1.

[0071] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention.

[0072] The number of groups of multiple solar cell module groups is not limited to the embodiment described above. String 2 only needs to be divided into multiple solar cell module groups such that the open-circuit voltage of each group is 165V or less. For example, as shown in Figure 6, each of the multiple solar cell module groups 6A to 6F may include three directly connected solar cell modules 6. That is, the multiple solar cell module groups may be divided by the first circuit breaker 4 and multiple second circuit breakers 5 so that each of the multiple solar cell module groups includes three solar cell modules 6 connected in series.

[0073] Furthermore, as shown in Figure 7, one second circuit breaker 5 may be provided for each of the multiple solar cell module groups, excluding the group to which the first circuit breaker 4 is connected (in this case, group 6A).

[0074] As shown in Figure 8, the first interruption device 4 may include a bypass diode 48 connected in parallel to any of the multiple solar cell module groups. In the example shown in Figure 8, the bypass diode 48 is electrically connected in parallel to group 6A. The bypass diode 48 includes an anode connected to the cathode terminal of group 6A and a cathode connected to the anode terminal of group 6A. Similarly, the multiple second interruption devices 5 may include a bypass diode 58 connected in parallel to any of the multiple solar cell module groups. In the example shown in Figure 8, the bypass diode 58 is electrically connected in parallel to both group 6C and group 6E.

[0075] In the above embodiment, the relay 44 of the first circuit breaker 4 had two contacts, a first switching section 44a and a second switching section 44b. However, as shown in Figure 9, the relay 44 may be composed of two relays, each having a single contact. That is, the control unit 43 of the first circuit breaker 4 may be configured to independently control the opening and closing of the first switching section 44a and the second switching section 44b. Similarly, in a plurality of second circuit breakers 5, the control unit 53 may be configured to independently control the third switching section 54a and the fourth switching section 54b of the relay 54.

[0076] In the above embodiment, the first circuit breaker 4 was connected to the circuit 8a connecting group 6A and group 6B, and to the circuit 8b connecting the inverter 3 and group 6A. However, the arrangement of the first circuit breaker 4 and the multiple second circuit breakers 5 may be swapped. For example, the first circuit breaker 4 may be connected to the circuit 8c and the circuit 8d, and the second circuit breaker 5a may be connected to the circuit 8a and the circuit 8b.

[0077] In the above embodiment, the first control signal was output to the first circuit breaker 4 by power line communication, but as shown in Figure 8, the first control signal may be output to the first circuit breaker 4 by wireless communication such as Wi-Fi (registered trademark). Alternatively, the inverter 3 and the first circuit breaker 4 may be configured to communicate with each other by wireless communication. For example, the first circuit breaker 4 may output an abnormal signal to the inverter 3 by wireless communication. Alternatively, the first circuit breaker 4 may be configured to output an abnormal signal to the user's mobile terminal by wireless communication.

[0078] In the above embodiment, the first blocker 4 determined that the second blockers 5a to 5c were abnormal if there was no feedback from them. However, the first blocker 4's determination of abnormality in the second blockers 5a to 5c is not limited to the above embodiment. For example, the first blocker 4 may periodically communicate with the second blockers 5a to 5c, and if there is no communication response from the second blockers 5a to 5c (i.e., the periodic communication is interrupted), the first blocker 4 may determine that the second blockers 5a to 5c are abnormal.

[0079] The status signals output from the second circuit breakers 5a to 5c are not limited to the above embodiment. The status signals output from the second circuit breakers 5a to 5c may include at least one of the voltage, current, or open / closed state of the relay 54 of the second circuit breakers 5a to 5c. The first circuit breaker 4 may determine that the second circuit breakers 5a to 5c are abnormal based on the information regarding the open / closed state of the relay 54, or it may detect welding of the relay 54 by monitoring the voltage between the contacts of the relay 54 based on the status signal and determine that the second circuit breakers 5a to 5c are abnormal. Furthermore, the status signals output from the second circuit breakers 5a to 5c may include information indicating that the second circuit breakers 5a to 5c are abnormal. In other words, the second circuit breakers 5a to 5c are configured to detect their own abnormalities by monitoring their own voltage, etc. That's fine.

[0080] The second circuit breakers 5a to 5c may be connected to the first circuit breaker 4 by two communication lines. In other words, the second circuit breakers 5a to 5c may be configured to communicate with the first circuit breaker 4 at all times.

[0081] The first circuit breaker 4 may output a status signal to the inverter 3 via power line communication or wireless communication. The inverter 3 may monitor the first circuit breaker 4 based on the status signal output from the first circuit breaker 4. If the inverter 3 determines that the first circuit breaker 4 is abnormal based on the status signal output from the first circuit breaker 4, it may output an abnormality signal to the display unit 34 or the user's mobile terminal to notify that the first circuit breaker 4 is abnormal. The status signal output from the first circuit breaker 4 may contain the same information as the status signals output from the second circuit breakers 5a to 5c. The status signal output from the first circuit breaker 4 may, for example, be feedback to the inverter in response to the output of a command signal to the relay 44 after receiving the first control signal, or it may include at least one of the voltage, current, or open / closed state of the relay 44 of the first circuit breaker 4, or it may include information indicating that the first circuit breaker 4 is abnormal. [Industrial applicability]

[0082] According to the present invention, it is possible to provide a solar power generation system that can achieve both a reduction in the installation cost of the shut-off device and an improvement in safety in a solar power generation system. [Explanation of symbols]

[0083] 1. Solar power generation system 2 strings 3 Inverter 4. First circuit breaker 5a~5c 2nd cutoff device 6. Solar cell modules 6A~6H Solar Panel Module Group 54 Relay (an example of an opening / closing mechanism)

Claims

1. A string comprising multiple groups of solar cell modules, each containing one or more solar cell modules connected in series, and each group of solar cell modules connected in series with respect to the others, An inverter connected to the string, which converts the DC power output from the string into AC power, A first circuit breaker connected to a first circuit that connects the multiple solar cell module groups, A second circuit breaker connected to a second circuit that connects multiple solar cell module groups that are different from the multiple solar cell module groups connected to the first circuit, Equipped with, The plurality of solar cell module groups in the string have an open-circuit voltage that is less than or equal to a predetermined open-circuit voltage for each group. The first circuit breaker disconnects the connections between the multiple solar cell module groups connected to the first circuit in response to a first control signal from the inverter, and monitors the second circuit breaker based on a second status signal output from the second circuit breaker. The second circuit breaker is connected to the first circuit breaker in a manner that allows bidirectional communication using a communication method different from power line communication, and disconnects the connections between the multiple solar cell module groups connected to the second circuit in accordance with the second control signal output from the first circuit breaker. Solar power generation system.

2. If the first circuit breaker determines that the second circuit breaker is malfunctioning in response to the second status signal, it outputs an abnormality signal. The photovoltaic power generation system according to claim 1.

3. When the first circuit breaker detects that the output of the second status signal has stopped, it determines that the second circuit breaker is malfunctioning. The solar power generation system according to claim 2.

4. The second circuit breaker is connected to the first circuit breaker by a single wire. A solar power generation system according to any one of claims 1 to 3.

5. The second circuit breaker includes an opening / closing unit that opens and closes the connections between the plurality of solar cell module groups connected to the second circuit, The second status signal includes information regarding the open / closed state of the opening / closing part, A solar power generation system according to any one of claims 1 to 4.

6. The inverter monitors the first circuit breaker based on a first status signal output from the first circuit breaker. A solar power generation system according to any one of claims 1 to 5.

7. The inverter, when it determines that the first circuit breaker is malfunctioning in response to the first status signal, outputs an abnormality signal. The solar power generation system according to claim 6.

8. The first circuit breaker disconnects the connections between the plurality of solar cell module groups connected to the first circuit in response to the first control signal from the inverter, and then outputs the second control signal to the second circuit breaker. A solar power generation system according to any one of claims 1 to 7.

9. The plurality of solar cell module groups in the string have an open-circuit voltage of 165V or less for each group. A solar power generation system according to any one of claims 1 to 8.

10. The plurality of solar cell module groups in the string include a first group, The first circuit breaker is driven by the power generated by one or more of the solar cell modules connected in series belonging to the first group. A solar power generation system according to any one of claims 1 to 9.

11. The plurality of solar cell module groups in the string include a second group, The second circuit breaker is driven by the power generated by one or more of the solar cell modules connected in series belonging to the second group. A solar power generation system according to any one of claims 1 to 9.

12. The inverter outputs the first control signal to the first circuit breaker via power line communication. A solar power generation system according to any one of claims 1 to 11.

13. The inverter outputs the first control signal to the first circuit breaker via wireless communication. A solar power generation system according to any one of claims 1 to 12.

14. At least one of the plurality of solar cell module groups of the string includes a plurality of solar cell modules connected in series, A solar power generation system according to any one of claims 1 to 13.

15. The photovoltaic power generation system according to any one of claims 1 to 14, wherein the first interruption device includes a bypass diode connected in parallel to any of the plurality of solar cell module groups.

16. The photovoltaic power generation system according to any one of claims 1 to 15, wherein the second circuit breaker includes a bypass diode connected in parallel to any of the plurality of solar cell module groups.

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