JP6240634B2 - Bypass diode failure inspection system - Google Patents

Description

  The present invention relates to a failure inspection apparatus for a bypass diode, and is particularly suitable for application to a photovoltaic power generation system in which a plurality of solar battery modules each having a bypass diode connected in parallel for each one or a plurality of solar cells are connected in series. The present invention relates to a failure inspection apparatus for a bypass diode.

  As a solar cell array of a photovoltaic power generation system, a configuration in which a plurality of solar cell strings configured by a plurality of solar cell modules connected in series are connected in parallel is widely used. Moreover, as a solar cell module, the structure which has one or several solar cell connected in series (henceforth a solar cell cluster), and the bypass diode was connected in parallel for every solar cell cluster is used widely. Yes. In the bypass diode, current flows in each solar cell module due to a failure, a shadow, or the like, and a current flows when a situation in which a reverse bias is applied to the solar cell module occurs. By such an operation of the bypass diode, it is possible to prevent the solar cell module (solar cell cluster) to which the reverse bias is applied from being heated or damaged.

  When the solar cell cluster is operating normally, a reverse bias is applied to the bypass diode connected in parallel to the solar cell cluster due to the voltage generated in the solar cell cluster, and the bypass diode is in a non-conductive state. Therefore, for example, even when the bypass diode fails and is in an open state (hereinafter also referred to as an open failure), the solar cell cluster connected in parallel to the failed bypass diode operates normally. However, when the bypass diode fails and is in an open state, the above-described effect of the bypass diode cannot be obtained. For this reason, various methods for detecting abnormality of the bypass diode have been proposed.

  For example, Patent Document 1 listed below acquires the IV characteristic in the forward direction of the bypass diode at night when the solar cell module does not generate power, and the acquired pattern of the IV characteristic and the normal I A method for diagnosing whether or not a bypass diode has failed by comparing with a -V characteristic pattern is disclosed.

  Further, Patent Document 2 described below applies a constant current from the negative electrode of the solar cell module toward the positive electrode at night when the solar cell module does not generate power. Disclosed is a failure detection device that determines a failure of a bypass diode based on a potential difference between the two.

JP 2011-066632 A JP, 2014-011427, A

In a solar cell string of a recent solar cell array, a large number of solar cell clusters are connected in series, and the number of bypass diodes connected in one solar cell string may be close to 100. When a voltage is applied to such a solar cell string in the forward direction of the bypass diode, in order to pass a forward current, at least a voltage obtained by multiplying the forward voltage Vf of the bypass diode by the number of all diodes is used. It is necessary to apply. For example, when 30 series crystal strings are assumed, the number of bypass diodes is considered to be about 90. When the forward voltage Vf of the bypass diode is 1.0 V, a voltage of 90 V or more is applied. There is a need.

  When a voltage is applied in the forward direction of the bypass diode, when all the bypass diodes operate normally, substantially equal voltages are applied to both ends (between the cathode and the anode) of each bypass diode. On the other hand, when there is a bypass diode having an open failure among these bypass diodes, a voltage of about forward voltage Vf is applied to both ends of the normal bypass diode, and solar cells are applied to both ends of the failed bypass diode. Of the voltage applied to the string, a portion excluding the voltage applied to both ends of the normal bypass diode is applied. The voltage is applied in the reverse direction to the solar cell cluster connected in parallel with the failed bypass diode.

  When performing the fault inspection of the bypass diode using the apparatus having the ability to apply the voltage of about 100V as described above, if the number of bypass diodes included in the solar cell string to be inspected is about 90, Since the reverse voltage applied to the solar cell cluster connected in parallel with the bypass diode is about several volts, it does not become a big problem. However, it is difficult to recognize in advance the number of bypass diodes in a solar cell array in actual use installed on the roof of a building or the like, and the magnitude of the applied voltage cannot be adjusted in advance.

  If the number of bypass diodes included in the solar cell string to be inspected is small, and if the solar cell string to be inspected contains an open-failed bypass diode, most of the voltage applied to the solar cell string has failed. It will be applied to the solar cell cluster connected in parallel with the bypass diode. Therefore, in the configuration in which a large voltage is applied at the start of the inspection as in Patent Documents 1 and 2 described above, a large reverse voltage is applied to the solar cell cluster connected in parallel with the failed bypass diode. . In this case, the solar cell cluster may be damaged due to the application of the reverse voltage. When the solar cell array is caused to generate power without noticing such damage to the solar cell cluster, an event such as heating or ignition may occur in the damaged solar cell cluster (solar cell module).

  If an occurrence of an open failure of a bypass diode is confirmed, if the solar cell module including the bypass diode is immediately replaced, it may not be a problem even if the solar cell cluster is damaged. . However, even if an open failure occurs in the bypass diode, the reverse voltage is applied to the solar cell cluster connected in parallel to the bypass diode in which the open failure occurs as a result of the current balance of each solar cell module being disturbed. As long as this does not occur, the solar cell array operates normally. For this reason, even when an open failure is found in the bypass diode, normally, the solar cell module or the like is not immediately replaced at the time when the bypass failure is found, and a response will be made later. In addition, power generation by the solar cell array is not prohibited until the countermeasure is taken. In addition, when the solar cell array is installed on the roof of a general house, for example, as disclosed in Patent Documents 1 and 2, when the bypass diode is inspected at night, the solar cell module or the like is immediately replaced. It is often difficult to perform work from the viewpoint of ensuring work safety and consideration for neighboring houses.

In the first place, even if a failure occurs in the inspection target, it is not preferable to deteriorate the inspection target in the inspection (change the state of the inspection target) itself, but even in view of the contents described above, In the failure inspection of the bypass diode, it is necessary to surely prevent the solar cell cluster from being damaged due to the inspection. In addition, in the above-mentioned patent documents 1 and 2, since such a problem is not recognized, it is difficult to cope with the problem.

  The present invention has been made in view of such a problem of the prior art, and is capable of detecting a failure of the bypass diode without damaging the parallel-connected solar cell clusters. An object is to provide an apparatus.

  In order to achieve the above object, the present invention employs the following technical means. First, the present invention provides a solar cell including a solar cell string in which a plurality of solar cell modules including one or a plurality of solar cells connected in series and a bypass diode connected in parallel with the solar cells are connected in series. It is assumed that a fault inspection device for a bypass diode in the array is used. The failure inspection apparatus for a bypass diode according to the present invention includes an anode side terminal, a cathode side terminal, a voltage source, a current detection unit, and a current interruption unit. The anode side terminal is connected to the negative electrode side of the solar cell string. The cathode side terminal is connected to the positive electrode side of the solar cell string. The voltage source applies a sweep voltage from the low voltage side to the high voltage side in the forward direction of the bypass diode included in the solar cell string to the solar cell string connected between the anode side terminal and the cathode side terminal. To do. The current detection unit detects the amount of current flowing through the solar cell string connected between the anode side terminal and the cathode side terminal. A current interrupting part interrupts | blocks the electric current which flows into a solar cell string, when the upper limit electric current amount designated beforehand is detected by the electric current detection part.

  In this bypass diode failure inspection apparatus, a sweep voltage from the low voltage side to the high voltage side is applied in the forward direction of the bypass diode included in the solar cell string. Therefore, even if an open fault bypass diode exists, a large reverse voltage is applied to the solar cells (solar cell clusters) connected in parallel to the bypass diode at the start of the inspection. Absent. In addition, when the amount of current flowing through the solar cell string in the process of applying the sweep voltage reaches a predetermined upper limit current amount, the current path is cut off, so that the solar connected in parallel to the open-failure bypass diode The voltage application can be stopped when a breakdown current caused by the reverse voltage flows through the battery cell (solar battery cluster). Therefore, it is possible to reliably prevent damage to the solar cells (solar cell clusters) connected in parallel to the open-failed bypass diode in the bypass diode inspection process.

  In the failure inspection apparatus for the bypass diode, a configuration in which the voltage source includes a battery, a booster, a capacitor, a voltage detector, and a variable resistor can be employed. The booster boosts the output voltage of the battery. The capacitor is charged by the output voltage of the booster. The voltage detector detects a voltage value between the anode side terminal and the cathode side terminal. The variable resistor is connected to the cathode side terminal and connected in series with the voltage value detection target by the voltage detection unit, and the resistance value is changed based on the detection result of the voltage detection unit, so that the charged capacitor is used. The above sweep voltage is applied between the anode side terminal and the cathode side terminal. With this configuration, it is possible to realize a portable bypass diode failure inspection device that is easy to carry outdoors. In this configuration, it is possible to adopt a configuration in which the variable resistor is configured by a transistor, and the current blocking unit blocks the current flowing through the solar cell string by turning the transistor off.

  In the above configuration, the failure of the bypass diode included in the solar cell string based on the voltage value applied between the anode side terminal and the cathode side terminal by the voltage source and the current amount detected by the current detection unit It is also possible to employ a configuration that further includes a determination unit that determines whether or not there is any.

  According to the present invention, it is possible to detect a failure of the bypass diode without damaging the solar cell clusters connected in parallel. In addition, since it can be easily reduced in size and weight, it is possible to realize a portable failure inspection device suitable for failure inspection of bypass diodes provided in outdoor solar cell arrays in actual use. is there.

1 is a schematic configuration diagram showing a configuration of a failure inspection apparatus according to an embodiment of the present invention. 1 is a schematic configuration diagram showing a specific example of the configuration of a failure inspection apparatus according to an embodiment of the present invention. The schematic diagram which shows the failure inspection of the bypass diode in one Embodiment of this invention

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating a configuration of a failure inspection apparatus for a bypass diode according to an embodiment of the present invention. The solar cell array included in the photovoltaic power generation system in an actual use state has a configuration in which a plurality of solar cell strings are connected in parallel. In FIG. 1, only one solar cell string 110 is shown in the drawing. ing.

  First, the solar cell string 110 will be briefly described. As shown in FIG. 1, the solar cell string 110 has a configuration in which a plurality of solar cell modules are connected in series. FIG. 1 illustrates a configuration in which three solar cell modules 11, 12, and 13 are connected in series. Each solar cell module 11, 12, 13 has a configuration in which solar cell clusters 121, 122, 123 and bypass diodes 131, 132, 133 are connected in parallel. The solar battery clusters 121, 122, 123 are configured by one or a plurality of solar battery cells connected in series. Each bypass diode 131, 132, 133 has a cathode side (cathode side) connected to the positive side of the solar cell clusters 121, 122, 123, and an anode side (anode side) of the negative side of the solar cell clusters 121, 122, 123. Connected to each side.

  As is well known, the bypass diodes 131, 132, and 133 cause current imbalance in each of the solar cell modules 121, 122, and 123 due to a failure or a shadow, and a reverse bias is applied to any of the solar cell modules. When a situation occurs, it becomes conductive. For example, when the situation where a reverse bias is applied to the solar cell module 12 occurs, the bypass diode 132 included in the solar cell module 12 becomes conductive. The operation of the bypass diode 132 can prevent the solar cell module 12 (solar cell cluster 122) to which the reverse bias is applied from being heated or damaged.

  Next, the failure inspection apparatus 100 for the bypass diode will be described. As shown in FIG. 1, the failure inspection apparatus 100 includes an anode-side terminal 1 connected to the output terminal 111 on the negative electrode side of the solar cell string 110 (the anode side of the bypass diodes 131, 132, and 133), and the solar cell string 110. The cathode side terminal 2 connected to the output terminal 112 on the positive electrode side (the cathode side of the bypass diodes 131, 132, 133). A voltage source 3 that applies a sweep voltage to the solar cell string 110 connected between the anode side terminal 1 and the cathode side terminal 2 is connected to the anode side terminal 1 and the cathode side terminal 2. The sweep voltage applied by the voltage source 3 is a sweep voltage from the low voltage side to the high voltage side, and is applied in the forward direction of the bypass diodes 131, 132, and 133. The voltage source 3 starts applying the sweep voltage in accordance with an instruction from an operator who operates the failure inspection apparatus 100.

Moreover, the failure inspection apparatus 100 includes a current detection unit 4, a current interruption unit 5, and a determination unit 6. The current detection unit 4 detects the amount of current flowing through the solar cell string 110 connected between the anode side terminal 1 and the cathode side terminal 2. In this example, the current detection unit 4 includes a voltage source 3 and a cathode side terminal 2.
It is the structure which detects the electric current amount between. The method for detecting the amount of current is not particularly limited, and any known method can be employed. For example, it is possible to adopt a configuration in which a current detection resistor is interposed in the current flow path and the amount of current is detected based on a potential difference generated at both ends of the current detection resistor.

  The current interrupting unit 5 interrupts the current flowing through the solar cell string 110 when a predetermined upper limit current amount is detected by the current detecting unit 4. In this example, the current interrupting unit 5 is configured by an enhancement type N-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor) interposed between the current detecting unit 4 and the cathode side terminal 2. Yes. In this configuration, the current detection unit 4 inputs a voltage (for example, ground potential) for turning off the MOSFET to the gate of the MOSFET that is the current cutoff unit 5 when detecting a current having a predetermined upper limit current amount. As a result, the current flowing through the solar cell string 110 is instantaneously interrupted.

  The determination unit 6 includes a bypass included in the solar cell string 110 based on the voltage value applied between the anode side terminal 1 and the cathode side terminal 2 by the voltage source 3 and the amount of current detected by the current detection unit 4. The presence / absence of a failure in the diodes 131, 132, 133 is determined. A specific determination method will be described later.

  FIG. 2 is a schematic configuration diagram showing a more specific configuration of the failure inspection apparatus 100 of the present embodiment. In FIG. 2, the description of the solar cell string 110 to be inspected is omitted. As shown in FIG. 2, in the present embodiment, the voltage source 3 includes a battery 31, a booster 32, a capacitor 33, a voltage detector 34, and a variable resistor 35.

  The booster 32 boosts the output voltage of the battery 31. Although not particularly limited, in the example of FIG. 2, the booster 32 is configured by a booster coil (flyback DC-DC converter), and the battery 31 and the primary circuit are turned on and off on the primary side of the booster 32. A switch 36 for switching to a state is connected. As the battery 31, for example, a commercially available dry battery can be used.

  A capacitor 33 that is charged by the output voltage of the booster 32 is connected to the secondary side of the booster 32. Although not particularly limited, in this embodiment, the capacitor 33 is configured by an electrolytic capacitor, and the positive electrode side is connected to the anode side terminal 1 and the negative electrode side is connected to the cathode side terminal 2. In the fault inspection apparatus 100 according to the present embodiment, the capacitor 33 can be charged with a voltage of about 130 V so that a voltage of about 100 V can be output as the upper limit of the sweep voltage. Note that diodes 37 and 38 for backflow prevention are interposed between the boosting unit 32 and the positive electrode of the capacitor 33 and between the capacitor 33 and the anode side terminal 1, respectively.

  The voltage detector 34 detects a voltage value between the anode side terminal 1 and the cathode side terminal 2. In the present embodiment, as shown in FIG. 2, the voltage detection unit 34 is between a potential detection position provided in the vicinity of the anode side terminal 1 and a potential detection position provided in the vicinity of the cathode side terminal 2. Detect potential difference. The detection method of a voltage value is not specifically limited, A well-known arbitrary method is employable. In this configuration, the voltage value applied between the anode side terminal 1 and the cathode side terminal 2 by the voltage source 3 is notified to the determination unit 6 by the voltage detection unit 34.

The variable resistor 35 is connected to the cathode side terminal 2 and is connected in series with a voltage value detection target (that is, the solar cell string 110) by the voltage detection unit 34. The variable resistor 35 changes the resistance value based on the detection result of the voltage detector 34, thereby using the charge of the charged capacitor 33 to change the above sweep voltage between the anode side terminal 1 and the cathode side terminal 2. Apply between.
Although not particularly limited, in the present embodiment, the variable resistor 35 is configured by a MOSFET that is the current interrupting unit 5.

  In this configuration, before the application of the sweep voltage is started, the resistance value of the variable resistor 35 is maintained at infinity (the MOSFET is in an off state). At this time, the voltage applied by the voltage source 3 to the solar cell string 110 connected between the anode side terminal 1 and the cathode side terminal 2 is 0V. Although not particularly limited, in the present embodiment, the voltage detection unit 34 inputs the voltage (here, the ground potential) that turns off the MOSFET to the gate of the MOSFET that is the variable resistor 35, so that the state is realized. ing.

  When the sweep start instruction by the operator is input, the voltage detection unit 34 decreases the resistance value of the variable resistor 35 by inputting a gradually increasing positive voltage to the gate of the MOSFET. Thereby, a sweep voltage gradually increasing from 0V is applied to the solar cell string 110 connected between the anode side terminal 1 and the cathode side terminal 2. In particular, in this configuration, the voltage detection unit 34 realizes voltage sweep at a constant speed by setting the magnitude of the positive voltage input to the gate of the MOSFET according to the voltage value detected by itself. In addition, in this configuration, sweeping at a relatively high speed of about several hundred msec is possible. When the MOSFET is operated as the variable resistor 35, the linear region of the MOSFET is used.

  Further, as described above, in the present embodiment, the MOSFET that constitutes the variable resistor 35 and the MOSFET that is the current cutoff unit 5 are constituted by the same MOSFET. Even in such a configuration, when the current detection unit 4 detects a current having a predetermined upper limit current amount, the current detection unit 4 does not depend on the voltage value input to the gate of the MOSFET by the voltage detection unit 34. It is possible to cut off the current flowing through the solar cell string 110 by inputting a voltage (here, ground potential) for turning the MOSFET off.

  When the inspection of the solar cell string 110 is performed using the failure inspection apparatus 100 according to the present embodiment, the negative electrode side output terminal 111 of the solar cell string 110 is connected to the anode side terminal 1 and the positive electrode side output terminal 112 is connected. The cathode side terminal 2 is connected. The electrical connection between the failure inspection apparatus 100 and one solar cell string 110 to be inspected is, for example, installed between a solar cell array and a power conditioner, and electric wiring connected to each solar cell string 110 is connected. This can be easily realized by using a collecting unit (collecting box) to be aggregated. In addition, the inspection of the bypass diodes 131, 132, and 133 by the failure inspection apparatus 100 is performed under a situation where the solar cell string 110 is not generating power, such as at night.

  When the connection is completed, the switch 36 is repeatedly switched on and off in accordance with an instruction from the operator, and the capacitor 33 is charged. When charging of the capacitor 33 is completed, switching of the switch 36 between on and off is stopped. The completion of charging of the capacitor 33 can be detected by the duration of the on / off switching operation of the switch 36, the potential difference between the positive electrode and the negative electrode of the capacitor 33, and the like. The completion of charging is preferably notified to the operator by any method that can be recognized by the operator, such as lighting of a charging completion lamp or generation of a charging completion sound.

  After the charging is completed, the voltage detector 34 changes the resistance value of the variable resistor 35 as described above in accordance with an instruction from the operator, and applies a sweep voltage to the solar cell string 110. Note that the application of the sweep voltage may be started automatically after the charging of the capacitor 33 is completed without obtaining an instruction from the operator. Although not particularly limited, in the present embodiment, the switch 36 of the primary circuit of the booster 32 is maintained in the OFF state while the sweep voltage is applied between the anode side terminal 1 and the cathode side terminal 2. The Thereby, the electric current detection part 4 and the voltage detection part 34 can acquire an electrical property more stably.

  FIG. 3 is a schematic diagram illustrating an example of a current detected when a sweep voltage is applied. In FIG. 3, the horizontal axis corresponds to the sweep voltage (voltage value detected by the voltage detection unit 34), and the vertical axis corresponds to the amount of current detected by the current detection unit 4. FIG. 3 illustrates a case where the number of bypass diodes included in the solar cell string 110 is relatively small (see FIG. 1).

  In FIG. 3, the solid line corresponds to the case where each bypass diode 131, 132, 133 is normal. The broken line corresponds to the case where any of the bypass diodes 131, 132, 133 has an open failure, and the solar cells connected in parallel to the failed bypass diode are of the front contact type. The dotted line corresponds to the case where any of the bypass diodes 131, 132, 133 has an open failure and the solar cells connected in parallel to the failed bypass diode are of the back contact type. As is well known, the front contact type has a structure in which one output electrode exists on the front surface side of the solar battery cell and the other output electrode exists on the back surface side of the solar battery cell. The back contact type has a structure in which both output electrodes are present on the back side of the solar battery cell. In this example, the upper limit current amount preset in the current detector 4 is 0.1A.

  When the bypass diodes 131, 132, and 133 are normal, a voltage is evenly applied between the anode and the cathode of each bypass diode 131, 132, and 133. 3, when the forward voltage Vf is applied between the anode and cathode of each of the bypass diodes 131, 132, and 133 (that is, applied between the anode side terminal 1 and the cathode side terminal 2). When the voltage is three times the forward voltage Vf), each of the bypass diodes 131, 132, 133 is turned on, and the forward current starts to flow rapidly. For example, when the forward voltage Vf of each bypass diode 131, 132, 133 is 1.0V, the detection current in the current detection unit 4 starts to flow when the sweep voltage exceeds 3.0V.

  On the other hand, when any of the bypass diodes 131, 132, 133 has an open failure, no current flows through the failed bypass diode. As a result, most of the voltage applied between the anode-side terminal 1 and the cathode-side terminal 2 (applied voltage −2 × Vf) is applied as a reverse voltage to the solar cell cluster connected in parallel to the failed bypass diode. The For example, in FIG. 1, when the bypass diode 132 has an open failure, a reverse voltage of 98 V is applied to the solar cell cluster 122 when the sweep voltage reaches 100 V.

  As can be understood from FIG. 3, when the solar cells constituting the solar cell cluster 122 are of the front contact type, an N-type high concentration impurity region and a P-type high concentration impurity region that realize an ohmic contact between the output electrode and the semiconductor. However, since it is provided apart from the front surface side and the back surface side of the solar battery cell, a reverse current does not flow even when a reverse voltage of 98 V is applied. Further, when the solar battery cells constituting the solar battery cluster 122 are of the back contact type, the N-type high-concentration impurity region and the P-type high-concentration impurity region that realize the ohmic contact between the output electrode and the semiconductor are formed in the solar battery cell. Since it is provided adjacent on the back side, it can be understood that a reverse current flows when the reverse voltage exceeds 20V. Therefore, when a reverse voltage of 98 V is applied to the solar battery cluster 122, a reverse breakdown may occur and the solar battery cell may be damaged.

  However, in the fault inspection apparatus 100 according to the present embodiment, when the upper limit current amount (here, 0.1 A) designated in advance by the current detection unit 4 is reached, the MOSFET that is the current cutoff unit 5 is turned off. Therefore, damage to the solar battery cell can be reliably prevented.

  The determination unit 6 determines whether there is a failure in the bypass diode by utilizing the above difference in the amount of current detected by the current detection unit 4 when the sweep voltage is applied. That is, the voltage value detected by the voltage detection unit 34 when the current detection unit 4 detects the start of forward current flow (for example, 1 mA forward current), and the current detection unit 4 reaches the upper limit current amount. When the difference from the voltage value detected by the voltage detection unit 34 when detected is relatively small (for example, less than 10 V, depending on the magnitude of the upper limit current value), the determination unit 6 is replaced with a bypass diode. It is determined that there is no failure. The voltage detection unit 34 detects the voltage value detected by the voltage detection unit 34 when the current detection unit 4 detects the start of forward current flow, and the voltage detection unit 34 when the current detection unit 4 detects arrival of the upper limit current amount. When the difference from the voltage value detected by the above is relatively large (for example, 10 V or more), or when the upper limit current amount is not detected during the voltage sweep, the determination unit 6 determines whether any bypass diode is present. Judge that it is broken. The notification of the determination result can be recognized by the operator, such as a message display indicating that there is a failure on the display included in the failure inspection apparatus 100, lighting or blinking of a lamp indicating that there is a failure, and issuing an alarm indicating that there is a failure. It can be implemented in any manner. Moreover, what is necessary is just to specify the solar cell module containing the failed bypass diode by test | inspecting individually about each solar cell module which belongs to the solar cell string by which the failure of the bypass diode was detected, for example.

  In the above description, the determination unit 6 is configured to determine the presence or absence of a failure of the bypass diode based on the voltage-current characteristics acquired for a single solar cell string. The structure which determines the presence or absence of a failure based on the relative comparison of the voltage-current characteristic of the some solar cell string to comprise may be sufficient. For example, the determination unit 6 compares the voltage-current characteristics acquired for each of the plurality of solar battery strings constituting the solar battery array, and the bypass diode fails in the solar battery string that shows characteristics different from other voltage-current characteristics. The structure which determines with there may be sufficient.

  As described above, in the fault inspection apparatus 100, the sweep voltage from the low voltage side to the high voltage side is applied in the forward direction of the bypass diodes 131, 132, and 133 included in the solar cell string 110. Therefore, even if an open-failed bypass diode exists, a large reverse voltage is not applied to the solar cell cluster connected in parallel to the bypass diode at the start of the inspection. In addition, when the amount of current flowing through the solar cell string in the process of applying the sweep voltage reaches a predetermined upper limit current amount, the current path is cut off, so that the solar connected in parallel to the open-failure bypass diode The voltage application can be stopped when a breakdown current due to the reverse voltage flows through the battery cluster. Therefore, in the inspection process of the bypass diode, it is possible to reliably prevent the solar cell cluster connected in parallel to the open failure bypass diode from being damaged. In addition, since a relatively large voltage can be output, it is possible to reliably perform a failure test on a recent solar cell string in which many bypass diodes are connected in series.

  In addition, since the failure inspection apparatus 100 can be operated with the battery 31, a portable failure inspection apparatus that can be easily carried outdoors can be realized. Therefore, it is possible to easily perform a failure inspection on a solar cell array that is actually used and installed on the roof of a building.

  The above-described embodiments do not limit the technical scope of the present invention, and various modifications and applications other than those already described are possible within the scope of the present invention. For example, in the above embodiment, as a particularly preferable mode, the determination unit 6 is provided. However, the determination unit 6 is not essential. For example, only the measurement result may be displayed on a display included in the failure inspection apparatus 100, and an operator or the like may determine whether or not there is a failure from the display.

  In the above embodiment, as a particularly preferable form, the variable resistor 35 and the current interrupting unit 5 are configured by the same MOSFET. However, the variable resistor 35 and the current interrupting unit 5 can be configured by individual transistors or the like. It is.

  Furthermore, the circuit configuration of the voltage source 3 shown in FIG. 2 is an example of a particularly preferable aspect, and does not exclude the adoption of other configurations. It is possible to change arbitrarily within the range where the effects of the present invention are exhibited, and it is also possible to adopt other circuit configurations that exhibit the same action.

  According to the present invention, it is possible to detect a failure of the bypass diode without damaging the solar cell clusters connected in parallel, which is useful as a failure inspection device for the bypass diode.

DESCRIPTION OF SYMBOLS 1 Anode side terminal 2 Cathode side terminal 3 Voltage source 4 Current detection part 5 Current interruption part 6 Judgment part 11, 12, 13 Solar cell module 31 Battery 32 Boosting part 33 Capacitor 34 Voltage detection part 35 Variable resistance 100 Fault inspection apparatus 110 Sun Battery string 111 Negative electrode side output terminal 112 Positive electrode side output terminal 121, 122, 123 Bypass diode 131, 132, 133 Solar cell cluster

Claims (3)

A bypass diode in a solar cell array including a solar cell string in which a plurality of solar cell modules including one or a plurality of solar cells connected in series and a bypass diode connected in parallel to the solar cells are connected in series A fault inspection device,
An anode side terminal connected to the negative electrode side of the solar cell string;
A cathode side terminal connected to a positive electrode side of the solar cell string;
A voltage source for applying a sweep voltage from the low voltage side to the high voltage side in the forward direction of the bypass diode to the solar cell string connected between the anode side terminal and the cathode side terminal;
A current detector for detecting the amount of current flowing through the solar cell string connected between the anode side terminal and the cathode side terminal;
A current interrupting unit configured to interrupt a current flowing through the solar cell string when a predetermined upper limit current amount is detected by the current detection unit;
With
The voltage source is
Battery,
A booster for boosting the output voltage of the battery;
A capacitor charged by the output voltage of the booster;
A voltage detector for detecting a voltage value between the anode side terminal and the cathode side terminal;
Connected to the cathode side terminal or the anode side terminal and connected in series with the voltage value detection target by the voltage detection unit, and changing the resistance value based on the detection result of the voltage detection unit, the charging A variable resistor that applies the sweep voltage between the anode-side terminal and the cathode-side terminal by a capacitor that is formed;
A failure inspection apparatus for a bypass diode. Wherein the variable resistance is a transistor, the current blocking unit blocks the current flowing through the solar cell string by the transistor in the OFF state, failure detection device of the bypass diode of claim 1, wherein. Based on the voltage value applied between the anode side terminal and the cathode side terminal by the voltage source and the amount of current detected by the current detection unit, the failure of the bypass diode included in the solar cell string The failure inspection apparatus for a bypass diode according to claim 1, further comprising a determination unit that determines presence or absence.

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