Patent ID: 12199559

DETAILED DESCRIPTION

FIG.1is a block diagram schematically showing a configuration of a solar power generation system1according to an aspect of the present invention. The solar power generation system1includes a string2, an inverter3, and a plurality of shut-off devices4ato4c.

The string2includes a plurality of solar cell modules5connected in series with each other. The string2in the present embodiment is composed of 16 solar cell modules5including the solar cell modules5ato5h. The string2includes a plurality of solar cell module groups each including the plurality of solar cell modules5.

Specifically, the string2includes a plurality of solar cell module groups in which the plurality of solar cell modules5are divided into three or more groups. The string2in the present embodiment includes solar cell module groups5A to5D in which the plurality of solar cell modules5are divided into four groups. In order to make the following explanation easier to understand, the solar cell module groups5A to5D will be described as groups5A to5D. The solar cell module5ais an example of a first solar cell module. The solar cell module5bis an example of a second solar cell module. The solar cell module5cis an example of a third solar cell module. The solar cell module5dis an example of the fourth solar cell module. The solar cell module5eis an example of the fifth solar cell module.

The group5A is connected to the group5B. The group5A includes at least the solar cell module5aand the solar cell module5bamong the plurality of solar cell modules5. The solar cell module5ais connected to the group5B. The solar cell module5bis connected to the solar cell module5a. As shown inFIG.1, the group5A in the present embodiment is composed of four solar cell modules5including the solar cell modules5aand5b.

The group5B is positioned between the group5A and the group5C and is connected to the group5A and the group5C. The group5B includes at least the solar cell module5cand the solar cell module5damong the plurality of solar cell modules5. The solar cell module5cis connected to the solar cell module5a. The solar cell module5dis connected to the group5C. The group5B in the present embodiment is composed of four solar cell modules5including the solar cell modules5c,5d, and two solar cell modules5disposed between the solar cell module5cand the solar cell module5d.

The group5C is positioned between the group5B and the group5D and is connected to the group5B and the group5D. The group5C includes at least the solar cell module5eand the solar cell module5famong the plurality of solar cell modules5. The solar cell module5eis connected to the solar cell module5d. The solar cell module5fis connected to the group5D. The group5C in the present embodiment is composed of four solar cell modules5including the solar cell modules5e,5f, and two solar cell modules5disposed between the solar cell module5eand the solar cell module5f.

The group5D is connected to the group5C. The group5D includes at least the solar cell module5gand the solar cell module5hamong the plurality of solar cell modules5. The solar cell module5gis connected to the solar cell module5f. The solar cell module5his connected to the solar cell module5g. The group5D in the present embodiment is composed of four solar cell modules5including the solar cell modules5gand5h.

That is, each of the solar cell module groups5A to5D in the present embodiment includes four solar cell modules5connected in series. The solar power generation system1may include a solar cell array in which a plurality of the strings2are connected in parallel.

The solar cell module5receives sunlight to generate electrical power, and outputs the generated electrical power to the inverter3. The open circuit voltage of the solar cell module5is, for example, 50V. The inverter3is connected to the string2via a power line6. The inverter3converts the DC power output from the solar cell module5ainto AC power. The inverter3is connected to a power system7and thereby supplies AC power to a commercial power system and a load device.

Specifically, the inverter3includes a DC/DC converter3a, a DC/AC inverter3b, and a control unit3c. The DC/DC converter3aconverts the voltage of the electrical power output from the solar cell modules5into a predetermined voltage that is input to the DC/AC inverter3b. The DC/AC inverter3bconverts the DC power output from the solar cell modules5into AC power via the DC/DC converter3a. The control unit3cincludes a CPU, a memory, and the like, and controls the DC/DC converter3aand the DC/AC inverter3b. Further, the control unit3coutputs a control signal to the shut-off devices4ato4cby power line communication.

The shut-off devices4ato4care disposed at a plurality of intermediate points of the string2and are configured to shut off a voltage output from the solar cell modules5in response to a control signal from the inverter3. The intermediate point here means an electric circuit to which the solar cell modules5are connected to each other. The shut-off devices4ato4care externally attached to the solar cell modules5.

The shut-off devices4ato4care not provided with a bypass diode. Therefore, when the voltage output from the solar cell module5ais shut off by the shut-off devices4ato4c, the voltage input to the inverter3is shut off.

The shut-off device4ashuts off the connection between the solar cell module5aand the solar cell module5cby shutting off the voltage output from the solar cell module5a. As a result, the connection between the group5A and the group5B are shut off. The shut-off device4ais connected to an electrical path8aand an electrical path8b. The electrical path8aconnects the solar cell module5aand the solar cell module5b. The electrical path8bconnects the solar cell module5aand the solar cell module5c. The shut-off device4ais driven by the electrical power generated by the solar cell module5a.

The shut-off device4bshuts off the connection between the solar cell module5dand the solar cell module5eby shutting off the voltage output from the solar cell module5d. As a result, the connection between the group5B and the group5C are shut off. The shut-off device4bis connected to an electrical path8cand an electrical path8d. The electrical path8cconnects the solar cell module5connected to the solar cell module5din the group5B and the solar cell module5d. The electrical path8dconnects the solar cell module5dand the solar cell module5e. The shut-off device4bis driven by the electrical power generated by the solar cell module5d.

The shut-off device4cshuts off the connection between the solar cell module5fand the solar cell module5gby shutting off the voltage output from the solar cell module5f. As a result, the connection between the group5C and the group5D are shut off. The shut-off device4bis connected to an electrical path8eand an electrical path8f. The electrical path8econnects the solar cell module5connected to the solar cell module5fin the group5C and the solar cell module5f. The electrical path8fconnects the solar cell module5fand the solar cell module5g. The shut-off device4cis driven by the electrical power generated by the solar cell module5f.

FIG.2is a block diagram schematically showing a configuration of the shut-off device4a. The shut-off device4aincludes a regulator11, a signal receiving unit12, a relay control unit13, a relay14a, and a bypass circuit15.

The regulator11uses the electrical power generated by the solar cell module5aas a power source to generate a drive power source for driving the shut-off device4aand supplies the drive power source in a stable state to the shut-off device4a. Here, the regulator11uses only the electrical power generated by a single solar cell module5(solar cell module5a) to generate the drive power source for the shut-off device4a. Since the drive voltage range of the regulator11can be kept small, the manufacturing cost of the shut-off device4acan be reduced.

FIG.3is a circuit diagram schematically showing a configuration of the regulator11. The configuration of the regulator11is a well-known configuration, and includes input terminals21a,21b, output terminals22a,22b, a line filter23, capacitors24,25, a booster circuit26, a switching element27, a control circuit28, a transformer29, a diode30, a DC/DC converter31, a feedback circuit32and the like.

The signal receiving unit12receives a control signal from the control unit3cof the inverter3and outputs the received control signal to the relay control unit13. Specifically, the signal receiving unit12receives the control signal from the control unit3cof the inverter3via a signal detecting unit16that detects the control signal from the control unit3cof the inverter3.

On the basis of the signal output from the signal receiving unit12, the relay control unit13controls the current value flowing through the coil of the relay14ato control the opening and closing of the contacts of the relay14a. The relay14ais disposed in the electrical path8d.

The relay14ais, for example, a mechanical relay in which contacts are connected in series and is capable of opening and closing a high-voltage direct current. When the drive power is not supplied to the shut-off device4a, the contacts of the relay14are always in the open state. Therefore, when the shut-off device4ais not driven, the connection between the group5A and group5B is shut off.

The bypass circuit15is a circuit for allowing the signal receiving unit12to receive the control signal from the control unit3cwhen the shut-off device4ais in a shut-off state. When the voltage output from the solar cell module5ais shut off by the shut-off device4a, the signal receiving unit12can receive the control signal from the control unit3cvia the bypass circuit15.

Since the configurations of the shut-off device4band the shut-off device4care the same as those of the shut-off device4aexcept that the connected electrical path is different from the shut-off device4a, descriptions thereof will be omitted.

Next, an example of the operation modes of the shut-off devices4ato4cwill be described with reference toFIG.4. The operation modes of the shut-off devices4ato4cinclude three operation modes of a start mode, an active mode, and a safety mode. The safety mode includes a normal shut-off mode and an emergency safety shut-off mode.

Therefore, the shut-off devices4ato4coperate in four operation modes: a start mode, an active mode, a normal shut-off mode, and an emergency safety shut-off mode.

The start mode is a mode when sunlight starts to hit the solar cell modules5. At this time, each of the solar cell modules5receives sunlight to generate electrical power. Then, the shut-off device4ais driven by the drive power source generated by the regulator11from the electrical power generated by the solar cell module5a. When the shut-off device4ais driven and the relay control unit13receives the control signal from the control unit3cof the inverter3via the signal receiving unit12, the relay control unit13performs control so as to close the contacts of the relay14aas shown inFIG.5. Similarly, the shut-off device4bis driven by the electrical power generated by the solar cell module5d, and closes the contacts of the relay14bdisposed in the electrical path8din response to the control signal from the control unit3cof the inverter3. Similarly, the shut-off device4cis driven by the electrical power generated by the solar cell module5f, and closes the contacts of the relay14cdisposed in the electrical path8fin response to the control signal from the control unit3cof the inverter3. As a result, the groups5A to5D are connected via the shut-off devices4ato4c, and the electrical power generated by each solar cell module5including the solar cell modules5ato5his output to the inverter3.

The active mode is a state in which each of the solar cell modules5receives sunlight during the day to generate electricity, which is substantially the same as the start mode. Therefore, in the active mode, the groups5A to5D are in a connected state via the shut-off devices4ato4c, and the electrical power generated by each of the solar cell modules5is output to the inverter3.

The normal shut-off mode is a mode when the solar cell modules5are not receiving sunlight during nighttime or due to the influence of the weather such as rain. Therefore, in the normal shut-off mode, electrical power is not generated by the solar cell modules5, and drive power source is not supplied from the solar cell module5ato the shut-off device4a. Similarly, drive power source is not supplied to the shut-off device4band the shut-off device4c. Therefore, in the normal shut-off mode, the connection between the solar cell module groups5A to5D is shut off. In the present embodiment, electrical power is supplied to the inverter3from the AC power supply, and the control signal is always output from the control unit3cof the inverter3except in the emergency safety shut-off mode.

In the normal shut-off mode, for example, when the power generation of the solar cell module5ais unstable due to unstable weather or the like, the relay operate on/off in response to the electrical power supplied by the solar cell module5a.

The emergency safety shut-off mode is a mode in which the connections between the groups5A to5D are shut off during the start mode or the active mode to stop the output of electrical power from the solar cell modules5to the inverter3. In the present embodiment, as shown inFIG.1, an operation switch35is connected to the inverter3, and when the operation switch35is operated while the shut-off devices4ato4care in the start mode or the active mode, the shut-off devices4ato4cswitch the operation mode to the emergency safety shut-off mode.

Specifically, when the operation switch35is operated, the control unit3cstops the output of the control signal. When the signal detecting unit16detects that the control signal has been stopped for a certain period, as shown inFIG.1, all the contacts of the relay14ato14care opened via the signal receiving unit12and the relay control unit13. As a result, the voltage output from all the solar cell modules5is shut off, and the connections between the groups5A to5D are shut off.

In the solar power generation system1having the above configuration, when the operation mode of the shut-off devices4ato4cis the emergency safety shut-off mode, the shut-off devices4ato4ccan shut off the plurality of solar cell modules5. As a result, the installation cost of the shut-off device can be reduced as compared with the case where the shut-off device is installed for each of the solar cell modules5. Further, it is possible to provide a solar power generation system having higher safety than the case where the solar cell module5aand the inverter3are shut off in the string2unit. Specifically, when the open circuit voltage each of the solar cell modules5is 50 V, the open circuit voltage for each of the solar cell module groups5A to5D in the present embodiment is 200 V, and the open circuit voltage of the string2becomes 800 V. Accordingly, if the solar cell modules5continue to generate power after the connection between the solar cell module groups5A to5D is shut off, the voltage of the solar cell module groups5A to5D becomes 200V at the maximum, and the safety is higher than when the connection with the inverter3is shut off in the string2unit.

Further, in the solar power generation system1, it is possible to secure communication between the drive power supply of the shut-off devices4ato4cand the inverter3by using the power line6. As a result, for example, when the shut-off devices4ato4care installed in an existing solar power generation system, additional wiring for connecting the inverter3and the shut-off devices4ato4cis not required. Therefore, it is possible to reduce the installation cost when installing the shut-off devices4ato4cin an existing solar power generation system.

Further, since the shut-off devices4ato4cmay be connected to one solar cell module5, the wiring is shorter and simpler than the case where the shut-off devices4ato4care connected across a plurality of solar cell modules5. As a result, for example, it is possible to reduce the installation cost when installing the shut-off devices4ato4cin an existing solar power generation system, and to perform the construction with high flexibility.

Further, since the bypass diode is omitted in the shut-off devices4ato4c, the manufacturing cost of the shut-off devices4ato4ccan be reduced.

Further, the bypass circuit15in the shut-off devices4ato4cenables the operation mode of the shut-off devices4ato4cto be switched from the emergency safety shut-off mode to the start mode according to the control signal of the control unit3c.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, with various modifications being possible without departing from the gist of the invention.

In the above embodiment, each of the groups5A to5D includes four solar cell modules5, but the number of the solar cell modules5is not limited to the above embodiment. Further, each of the groups5A to5D does not necessarily include the same number of solar cell modules5. For example, group5A may include four solar cell modules5and group5B may include five solar cell modules5.

In the embodiment, the string2includes four groups5A-5D, but the number of groups is not limited to the embodiment. For example, string2may include five groups. Further, the arrangement and the number of the shut-off devices4ato4care not limited to the above-described embodiment.

In the above-described embodiment, switching to the emergency safety shut-off mode is performed by operating the operation switch35, but switching from the start mode or the active mode to the emergency safety shut-off mode is not limited to the above-described embodiment. For example, the solar power generation system1may be provided with a sensor that detects the output state of the solar cell modules5. The control unit3cof the inverter3may stop the output of the control signal when an abnormality is detected from the output state of the solar cell modules5detected by the sensor, and shut-off devices4ato4cmay shut off the connections between the groups5A to5D. Alternatively, when a fire alarm communicator or a fire alarm is connected to the inverter3, the inverter3may stop the output of the control signal when the inverter receives a signal from the fire alarm communicator or fire alarm, and the shut-off devices4ato4cmay shut off the connections between the groups5A to5D.

REFERENCE NUMERALS

1Solar power generation system2String3Inverter4a-4cShut-off device5A-5D Solar cell module group5Solar cell module6Power line8a-8fElectrical path12Signal receiving unit15Bypass circuit