KR101868433B1 - Photovoltaic power generation system with string block device for preventing solar module string accident - Google Patents

Abstract

Incorporating accidental spread of solar power generation (String block device which can prevent control of high voltage direct current power generated from solar module string to prevent accident spreading, fire spreading, accidental accident such as accident of electric shock to commercial power source) And a connection block provided with the STRING BLOCK DEVICE.
Wherein the connection module is installed between a solar module string connected in series with a plurality of solar modules and an inverter converting DC power output from the solar module string into AC power, And outputting the solar module string to the inverter, the connection panel comprising: a detector for collecting data for determining whether the solar module string is operating normally; And an operation unit for limiting a power output of the solar module string according to the normal operation of the solar module string by analyzing the data collected from the detector unit.

Description

TECHNICAL FIELD [0001] The present invention relates to a connection block for a photovoltaic power generation system having a string block device for preventing an accident of a string of photovoltaic modules, and a photovoltaic power generation system including the same,

A string block device (STRING BLOCK DEVICE) is applied to a grid-connected system composed of a solar module string, a connection panel, and an inverter to prevent an accident from spreading by selectively blocking an abnormal circuit during a solar power generation operation .

In general, solar power generation systems are being actively researched and developed in advanced countries as a countermeasure against global environmental problems and diversification of future energy sources, owing to the pollution and infinite qualities of solar energy.

Such a photovoltaic power generation system is classified into a stand-alone power generation system that stores generated power in a battery and supplies power at a required time according to the utilization method of the developed power, and a grid-type power generation system that supplies power to the load and supplies surplus power to the system Power generation system.

In recent years, grid-connected power generation systems have been spreading by minimizing the influence of distributed power systems, protecting system against accidents, and improving control technology of inverters.

The grid-connected power generation system includes a solar cell array unit including a plurality of solar cell strings in which a plurality of solar modules are connected in series, a connection unit for outputting the combined DC power output from the solar cell strings, And an inverter that converts the output DC power into AC power and supplies the AC power to a load or a commercial system.

At this time, a fuse, a reverse current prevention diode, a current transformer, and the like are installed in the connection module for improving power distribution efficiency and safety function.

In recent years, as the supply of photovoltaic power generation system has been rapidly increased, a remote management system for monitoring and monitoring the operation state of the whole photovoltaic power generation system has been actively introduced.

However, since the conventional monitoring system of the solar power generation system monitors the total generation voltage and current of the solar cell array unit, or monitors the generation voltage and current of each solar cell string, the solar cell modules in the solar cell string It is impossible to grasp the detailed abnormality such as a ground fault and a short circuit with respect to the solar cell array, and thus it takes a lot of time and cost to maintain and repair the solar cell array portion. In addition, when an abnormality occurs on the line installed in the connection panel to connect the solar cell array part and the inverter, considerable effort and time are consumed to check the faulty part and to repair it, .

For example, in a conventional solar module, power generation efficiency may deteriorate due to deterioration of the power generation state or damage of the module due to various obstacles, and in some cases, damage is spread to the adjacent module or the entire system. In such a damaged photovoltaic module with reduced power generation area, power generation capacity is reduced. If a module located within a string is damaged by such a module or external factors, it will adversely affect neighboring modules constituting the string through the serial connection with the module and cause a reduction in the power generation of the entire string.

If the power of a specific string decreases in a connection string connected with a plurality of strings, a load is generated in a reverse current prevention diode configured to prevent a reverse current flow in a connection half due to a difference from a generation amount of a normal string. As a result, not only damage to equipment but also fire and electric shock accidents occur, resulting in a considerable adverse effect on safety and power generation efficiency.

In addition, due to overcurrent, ground fault current due to short circuit of PV module input cable, continuous leakage current due to crack of PV module, connection failure in PV module, and occurrence of series arc due to faulty processing of wrong cable terminal Fire may also occur.

Meanwhile, as the photovoltaic power generation environment becomes larger and more farmed, the number of photovoltaic modules installed in one place is surging, and a management center monitors the status of photovoltaic devices in various regions, The number of modules managed by the center is in the range of thousands to tens of thousands. In particular, in order to cope with the abnormal situation of each module, the management center integrally manages the set relation of modules and strings that can be changed according to the status and situation of each of these modules, information of each module and old information, It is difficult to cope with a problem caused by a network situation or an error in inputting information.

Patent Registration No. 10-1529476 (Date of Publication: June 29, 2015)

A STRING BLOCK DEVICE (STRING BLOCK DEVICE) is applied to a grid connection system composed of a solar module string, a connection panel, and an inverter to selectively prevent an abnormal circuit in the solar power generation operation, .

It is an object of the present invention to provide a solar module module, which is installed between a solar module string connected in series with a plurality of solar modules and an inverter which converts DC power outputted from the solar module string into AC power, And outputting DC power to the inverter, the connection panel comprising: a detector for collecting data for determining whether the solar module string is operating normally; And an operation unit for limiting the power output of the solar module string according to whether the solar module string is normally operated by analysis of the data collected from the detection unit.

The detecting unit includes a ground fault section detecting section for detecting a ground fault section of the solar module string, a leakage current detecting section for detecting a leakage current of the solar module string, a fault current detecting section for detecting a fault current of the solar module string, And a detection unit.

The detection unit may further include a temperature detection unit installed on a line connecting the solar module string and the connection unit to measure temperature.

The detection unit may further include a fire detection unit for detecting a fire in the connection unit.

The connection module according to the present invention may further include a control unit for limiting the power output of the connection module according to the normal operation of the connection module by analyzing the data collected from the detection module.

The alarm system may further include a solar module string by analyzing the data collected from the detector, and an alarm system for providing status information of the connection module.

On the other hand, in the connection panel according to the present invention, there are a plurality of the solar module strings, and the detection section is provided corresponding to the number of the solar module strings, and the operation section analyzes the data collected from the detection sections To selectively limit the output of the photovoltaic module string to non-normal operation depending on whether the solar module string is operating normally.

By applying a STRING BLOCK DEVICE according to the present invention to a photovoltaic power generation system, it is possible to prevent an accidental ripple (control of a high voltage DC power generated in a solar module string by selecting and blocking an abnormal circuit during a solar power generation operation It is possible to prevent accidents from spreading to commercial power, spreading of fire, accidental accidents such as electric shock accident).

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a solar power generation system,
FIG. 2 is a schematic view of a solar power generation system according to the present invention,
3 is a diagram illustrating an embodiment of a solar power generation system according to the present invention,
4 shows a connection panel of a solar power generation system according to the present invention.

Prior to the description of the present invention, the ground fault current detection method included in the technical idea of the present invention will be described as follows. The ground fault current detection method differs depending on the grounding method of the line. In general, 1) Neutral point direct grounding method and low resistance grounding method are used. 2) Ground fault current detection method using neutral point direct grounding method, low resistance grounding method, and high resistance grounding type neutral sensor CT (Current Sensor). 3) High-resistance grounding method, detection method using a non-grounding video current transformer. 4) low-resistance grounding system, and 3-wire CT using neutral point direct grounding system of low-voltage system.

The characteristics of each detection method are as follows. The residual circuit use detection method is generally adopted when the rated current is 400 A or less. However, since the magnitude of the ground fault current is determined according to the contact resistance of the low voltage direct line type neutral ground, It is difficult to obtain the magnitude of the ground voltage and the neutral point grounding resistance at the time of ground fault and the large current that can operate the ground fault point. For example, if the low-voltage line-to-line voltage is 440V and the neutral-point grounding resistance is 5Ω, and the contact resistance is ignored, the magnitude of the ground fault current is 440 / √3 ÷ 5 = 50.8 [A] Even if it is adjusted, ACB breaking current should be more than 60A, so the current in the above formula can not block ACB. The ground fault current detection method using the neutral grounding wire CT is a method of detecting the ground fault current by detecting the ground fault by grounding the neutral point in the 3-phase 4-wire type and installing the CT on the ground wire, thereby preventing malfunction due to the load unbalance current. , It is the most reasonable method to detect the ground fault current in the low-voltage path. Ground fault detection method using video current transformer The ground fault current of the line is about several hundred mA due to the detection method used for high resistance ground or non-grounded method. The 3-winding CT detection method utilizes a CT that has a separate winding to detect a ground fault current instead of a 2-winding CT that is generally used to change the current. In general, a low-resistance grounded system with a rated current exceeding 300 A It is mainly used, and the ratio of 3rd winding is always 100 / 5A. It is possible to adopt the neutral point direct method of the low pressure system, but the price of the device is expensive, so it is necessary to examine economical efficiency etc. when selecting.

It is recommended to use the CT for ground fault detection on the neutral wire grounding line because if the CT ratio is large, the ground fault current detected during the ground fault becomes less than the minimum correction value of the OCB built-in OCGR and the ACB can not block the fault current in case of a ground fault, Ground fault current is detected by using appropriate ratio of CT to the ground wire.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

The connection panel of the present invention can not control the high voltage DC power generated in the solar module string 100 in the photovoltaic generation system 1000 as shown in FIG. (STRING BLOCK DEVICE, hereinafter, referred to as SBD 200) that can prevent the occurrence of an accident such as spread, fire spread, electric shock, and the like.

Specifically, a plurality of solar modules 110 and 120 are provided in series between the solar module string 100 and the inverter 400 for converting DC power output from the solar module string 100 into AC power, A connection panel (300) for a photovoltaic power generation system for outputting direct current power output from a solar module string (100) to the inverter (400), the connection panel (300) comprising data for determining whether the solar cell module string And an operation unit for limiting the power output of the solar module string 100 according to the normal operation of the solar module string 100 by analyzing the data collected from the detector unit 210. [ (250).

In this case, the number of the solar module strings 100 may be plural, and the detection unit 210 may be provided corresponding to the number of the solar module strings 100. The operation unit 250 selectively outputs the output of the solar module string 100 that is not normal operation according to whether the solar module string 100 is operated normally by analyzing the data collected from the detection units 210 Can be limited.

The detection unit 210 and the operation unit 250 constitute the SBD 200. The detection unit 210 of the SBD 200 collects data for determining whether the solar module string 100 is operating normally And may be provided in the solar module string 100 and the connection module 300 in order to achieve the same. The detection unit 210 includes a ground fault section detection unit for detecting a ground fault section of the solar module string 100, a leakage current detection unit for detecting a leakage current of the solar module string 100 and the connection unit 300, A temperature detection unit installed on a line connecting the solar module string 100 and the connection unit 300 to measure the temperature, a temperature detection unit for detecting temperature of the connection string 300, And a fire detection unit for detecting a fire of the vehicle.

The connection unit 300 further includes a control unit 310 that limits the power output of the connection unit according to whether the connection unit 300 is operated normally by analyzing the data collected from the detection unit 210. [

The control unit 310 may perform a function of analyzing data collected from the detection unit 210. 2 to 3, the controller 310 performs a function of analyzing data collected from the detector 210. On the other hand, the control unit 310 of the connection unit 300 performs a function of the general access unit 300 The SBD 200 may perform a function of separately providing a control unit and analyzing data collected from the detection unit 210. [

On the other hand, the connection module 300 may include an alarm system (not shown) to provide status information of the solar module string 100 and the connection module 300 by analysis of the data collected from the detection module 210 have. Such an alarm system can be guided by applying a step-by-step risk, for example, a safety mode, a warning mode, and a dangerous mode.

In the case of the safety mode, it means that the solar power generation system 1000 is normally operated, and can be displayed as green light. The warning mode means that the abnormal circuit occurred in the measurement data and the corresponding circuit is blocked through the SBD (200) and can be displayed as red light. The dangerous mode may be a fire situation. In this case, the termination of the solar power generation system 1000 and the opening of the connection DC main breaker, the last connection to the SBD 200, .

Meanwhile, the solar power generation system 1000 of the present invention includes the connection panel 300 as described above.

4 is a block diagram of a STRING BLOCK DEVICE (hereinafter referred to as "SBD 200") applied to a grid connection system composed of a solar module string 100, a connection board 300 and an inverter 400, A solar cell system 1000 having a function of preventing an accident from spreading is provided. In the solar cell system 1000, the connection panel 300 is most frequently exposed to fire and accidents, It is possible to prevent the spread of the fire and the electric shock accident by opening the inlet and outlet of the connection unit 300 in order to prevent the accident from spreading. The cause of fire in solar power generation is generally caused by overcurrent, ground fault current, reverse current prevention diode and insulation breakdown due to temperature short circuit due to short-circuit of the solar cell lead-in cable, insulation breakdown due to continuous leakage current caused by crack of solar cell, 4, the present invention is a method for detecting such phenomena, including a ground fault section detection sensor 211, a leakage detection section A sensor 212, an arc detection sensor 213, and a line temperature detection sensor 214. The sensor value detected by these sensors is processed to allow the SBD 200 to operate when it is greater than a predetermined value .

4, the SBD 200 functions to shut off the input power when an abnormality occurs. The control unit 310 controls the SBD 200, and the sensor values input to the control unit 310 are input to the solar module The leakage current detection unit 211 detects the leakage current flowing through the insulation resistance and detects the leakage current flowing through the insulation resistance, The leakage current value is amplified through the circuit board to obtain a signal. The micro current value is input to the control unit 310. When the arc detection sensor 213 generates a spark light arc, the detection signal is input to the control unit 310 through the arc / temperature detection unit, In the method of measuring the insulation resistance, a DC voltage generating unit generates a voltage, an insulation resistance is transmitted from the measurement unit to the control unit 310, Lt; / RTI > The controller 310 controls all of the above situations and operates the wiring breaker (MCCB) to interrupt power when an abnormal signal such as a leakage current or a fire is detected.

More specifically, the function of the SBD 200 will be described as follows: 1) The insulation resistance standard range of the insulation resistance measuring solar cell module is set to 40 M / m < 2 >, and when the solar cell module string voltage (0 V) After the insulation resistance is measured three times in the generator and the insulation resistance measuring part, the minimum value is stored in the control part and the operation of the SBD (200) is determined. 2) The leakage current measurement function can not measure the insulation resistance of the solar cell module string in the live state. Therefore, the leakage current using the leakage detection sensor 212 of FIG. 4 is monitored, Only the string is selectively cut off by the operation unit 250 of the SBD 200, and the pulse current generation unit and the detection unit are operated to detect the ground fault period, and in the control unit, the manager instructs the ground fault period 3) Solar cell string incoming circuit The series arc and temperature measurement function is a function of the incoming arc detection sensor 213 of the solar cell string and the line temperature detection sensor 213 of the solar cell string. The arc thermometer side part 214 is provided to determine whether or not an arc is generated and measure the temperature of the incoming circuit to selectively open an abnormal string circuit in the SBD 200 to prevent an accident caused by a short arc, By monitoring the frequency waveform of each solar cell string circuit, it is judged whether or not an arc is generated. When the waveform change is suddenly changed, the input value is transmitted to the controller, so that the SBD 200 senses an accident and opens it selectively. 4) The step-by-step method of risk application shows that the safety status is normal operation of the power generation system and the green light is on and the warning status is the abnormal status of the measurement data. The abnormal circuit selection open red light is turned on and displayed in the display unit 200. [ The danger step is constituted in such a manner that the power generation system is stopped, the connection half DC main breaker is opened, the SBD is opened last time, and the yellow light is lit and displayed.

5 is a view for explaining a process of detecting a leakage current and limiting a direct current power output to the inverter according to whether leakage current is detected or not in the present invention. Referring to FIG. 5, the solar power generation system 1000 'includes a plurality of solar cell arrays 110' connected in parallel, a DC voltage generated in each solar cell array 110 ' , An inverter 130 'for converting the supplied DC voltage into an AC voltage, and a monitoring device 140' for monitoring the overall operation state of the solar power generation system 1000 ' . According to FIG. 5, a plurality of solar cell arrays 110 'are connected in parallel. The solar cell array 110 'is a circuit in which a plurality of solar cell modules are connected in series and combined to satisfy a predetermined output voltage. Each of the solar cell modules has a plurality of solar cells connected in series. The solar cell array 110 'generates a direct current voltage and generates a current. The generated current flows along the closed circuit between the solar cell array 110 ', the connection panel 120' and the inverter 130 '. The current generated in the solar cell array 110 'can be divided into an input current supplied to the inverter 130' and an output current passed through the inverter 130 '. The connection panel 120 'merges the DC voltages generated in the plurality of solar cell arrays 110' and supplies the combined DC voltages to the inverter 130 '. The connection unit 120 'includes a fuse 121' connected in series to each output terminal of the solar cell array 110 ', a reverse voltage prevention unit 122' connected in series to each fuse 121 ' A leakage current detection sensor 125 'connected to the output terminal of the leakage current detection sensor 125', an amplifier 126 'amplifying the induced voltage induced in the leakage current detection sensor 125' And a connected operation unit 250. The connection unit 120 'measures the output terminal current of the voltage measurement unit 123' and the reverse voltage prevention unit 122 'that measure the voltage between the fuse 121' and the reverse voltage prevention unit 122 ' And a controller 127 'for transmitting the state between the solar cell array 110' and the inverter 130 'to an external monitoring device 140'. The fuse 121 'is connected in series to the respective output terminals of the plurality of solar cell arrays 110'. The fuse 121 'will be short-circuited if a DC current exceeding the specified value is input. Accordingly, the fuse 121 'prevents the overcurrent from being drawn into the connection board 120', thereby protecting the circuit of the connection board 120 '. The reverse voltage prevention portion 122 'is connected in series to each fuse 121' for individually protecting the solar cell array 110 '. The reverse voltage prevention portion 122 'allows the current to flow only in one direction and not to flow in the reverse direction. Accordingly, the reverse voltage prevention unit 122 'protects the solar cell array 110' from the abnormal current flow. The voltage measuring unit 123 'measures an individual voltage between the fuse 121' and the reverse voltage prevention unit 122. Each voltage value measured at the voltage measuring unit 123 'is transmitted to the monitoring device 140' via the controller 127 '. The manager can monitor the amount of power generated by each solar cell array 110 'by monitoring each voltage value transmitted to the monitoring device 140'. Therefore, it is possible to confirm the abnormality of the solar power generation system 1000 'and the amount of power generation in real time. It is also possible to determine whether each fuse 121 'is short-circuited and whether each of the reverse voltage prevention units 122' is abnormal. The current measuring unit 124 'measures the output terminal current of the reverse voltage prevention unit 122'. The current value measured by the current measuring unit 124 'is transmitted to the monitoring device 140' through the controller 127 '. The leakage current detection sensor 125 'detects a ground fault and a leakage current by measuring a magnetic flux generated according to a difference in current between an input current supplied to the inverter 130' and an output current outputted through the inverter 130 ' . Specifically, the solar cell array 110 'generates a DC voltage and generates a current according to a simplified diagram for explaining the operation of the ground fault and leakage current detection device. The generated current flows along the closed circuit between the solar cell array 110 'and the inverter 130'. The generated current can be divided into an input current supplied to the inverter 130 'and an output current passed through the inverter 130'. Here, if there is no ground fault and leakage current in the closed circuit between the solar cell array 110 'and the inverter 130', the input current and the output current are equal and no magnetic flux is generated around the leakage current detection sensor 125 '. However, if there is a ground fault and a leakage current in the closed circuit between the solar cell array 110 and the inverter 130, the input current and the output current are different, and a magnetic flux is generated around the leakage current detection sensor 125 '. Therefore, the leakage current detection sensor 125 'detects that a ground fault and leakage current have occurred in the closed circuit between the solar cell array 110' and the inverter 130 'due to the occurrence of the magnetic flux. The leakage current detection sensor 125 'induces the induced voltage through the magnetic flux generated around the leakage current detection sensor 125'. The amplifier 126 'amplifies the induced induced voltage. The amplified voltage cuts off the actuating part 250 through the control device 127 'to cut off the closed circuit. Also, the controller 127 'transmits the information that disconnects the operation unit 250 to the monitoring device 140' according to the occurrence of the ground fault and the leakage current. Therefore, when the ground fault and leakage current occur, the photovoltaic power generation system 1000 'can be quickly stopped to secure safety. In addition, the photovoltaic system 1000 'can be protected against ground and leakage currents. The control device 127 'transmits information such as the voltage value measured by the voltage measuring unit 123', the current value measured by the current measuring unit 124 ', and the operation state of the operation unit 250 to an external monitoring device 140 '. Although not shown, a fire alarm, a motion detection sensor, and the like may be added to the inside of the connection panel 120 'so as to be monitored by the monitoring device 140'. The control device 127 'also controls the ON / OFF operation of the operation unit 250 according to the control signal of the monitoring device 140'. The inverter 130 'is supplied with the DC voltage generated from the plurality of solar cell arrays 110' through the connection panel 120 '. The inverter 130 'converts the supplied DC voltage into an AC voltage. The AC voltage converted in the inverter 130 'is supplied to the load using the AC voltage.

The monitoring device 140 'monitors the operation state and abnormality of the solar power generation system 1000' from the outside. The monitoring device 140 'collectively monitors the information transmitted from the controller 127' installed in the connection panel 120 'and the information transmitted from the inverter 130', and allows the administrator to grasp the information remotely. That is, the overall operation state of the solar power generation system 1000 'is monitored. The monitoring device 140 'can also widely manage a plurality of connection units 120' and a plurality of inverters 130 '. The monitoring device 140 'provides information such as current power generation amount, accumulation amount, operation information of each connection panel 120', operation information of each inverter 130 ', abnormal condition occurrence signal, etc. to the manager. The administrator can identify and manage the current operation status with the provided information. Therefore, the administrator can prevent the quick recovery according to the abnormal operation and the recurrence of similar accidents. The monitoring device 140 'is connected to the wireless terminal through a communication network (not shown). The manager can check the real-time status of the solar power generation system 1000 'from the outside through the wireless terminal. Also, when the solar power generation system 1000 'stops operating due to a ground fault and a leakage current, the monitoring system 140' notifies an administrator's wireless terminal of an error occurrence message. With such a configuration, the operation of the photovoltaic power generation system 1000 'can be quickly interrupted when a ground fault or a short circuit is generated, thereby securing safety, thereby preventing the risk of human accidents in advance. In addition, the management efficiency of the photovoltaic power generation system 1000 'can be improved by quickly judging and managing the abnormality of the photovoltaic power generation system 1000'.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

100: Solar module string
200: SBD
300: Connection board
400: Inverter

Claims (9)

A plurality of photovoltaic modules are connected in series between a solar module string connected in series and an inverter for converting DC power output from the solar module string into AC power and outputting DC power output from the solar module string to the inverter 1. A connection panel for a solar power generation system,
A detector for collecting data for determining whether the solar module string is operating normally;
An operation unit for limiting the power output of the solar module string according to the normal operation of the solar module string by analysis of the data collected from the detection unit; And
An alarm system for providing status information of a solar module string and a connection module by analyzing data collected from the detection unit; And
And a controller for limiting the power output of the connection module according to whether the connection module is normally operated by analyzing the data collected from the detection module,
Wherein the plurality of solar module strings are provided in correspondence with the number of the solar module strings,
The solar module string includes a ground fault section detection sensor, a leakage detection sensor, an arc detection sensor, and a line temperature detection sensor. The sensor module processes the sensor value detected by the sensors, And a SBD (String Block Device) composed of the detection unit and the operation unit performing the function,
Wherein the detecting unit comprises: a ground fault section detecting section for detecting a ground fault section of the photovoltaic module string; a leakage current detecting section for detecting a leakage current of the photovoltaic module string and the connecting section; A temperature detecting unit installed on a line connecting the solar module string and the connection module to measure temperature, and a fire detector for detecting a fire in the connection module,
The operation unit is connected in series to an output terminal of the detection unit to selectively limit the output of the solar module string that is not normal operation according to the normal operation of the solar module string by analyzing the data collected from the detection units,
The control unit analyzes the data collected from the detection unit and operates the circuit breaker to cut off power when an abnormal signal is generated due to the leakage current,
The alarm system is divided into a safety mode, a warning mode, and a danger mode by applying a step-by-step risk diagram.
In the safety mode, the solar power generation system is normally operated,
The warning mode indicates a state where an abnormal circuit is generated in the measurement data and the corresponding circuit is blocked through the SDB (String Block Device) and is displayed as red light.
The dangerous mode may be a state in which a fire has occurred. In this case, the operation of the photovoltaic power generation system is suspended, the connection main circuit DC main breaker is opened, all circuits connected to the SBD are opened, half.
delete delete delete delete delete delete A photovoltaic power generation system comprising a connection panel of claim 1.
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