Solar power generation system and short circuit detection method for solar power generation system

Abstract

Provided is a solar power generation system that detects a short circuit of a series solar cell module. A solar power generation system (1) is provided with a solar cell string (10) to which M series solar cell modules (20) are connected, and a short circuit detection device (32). The M bottom-side solar cell sub-modules (22) form a series-connected bottom-side solar cell string (12), and the M top-side solar cell sub-modules (24) form a series-connected top-side solar cell string (14). The short-circuit detection device (32) measures the potential difference (Vps +) between the positive potential terminal of the bottom-side solar cell string (12) and the positive potential terminal of the top-side solar cell string (14), and measures the potential difference (Vps-) between the negative potential terminal of the bottom-side solar cell string (12) and the negative potential terminal of the top-side solar cell string (14). When the absolute value of the potential difference (Vps +) and the absolute value of the potential difference (Vps-) are greater than 0 V, a short circuit of the tandem solar cell module (20) is detected.

Description

Technical Field

[0001] This invention relates to a solar power generation system and a short-circuit detection method for a solar power generation system. Background Technology

[0002] A solar power generation system comprises: a solar cell string consisting of multiple solar cell modules connected in series; and a power conditioner (also known as a power conditioning system: PCS) that converts the direct current (DC) power from the solar cell string into the desired alternating current (AC) or direct current (DC) power. In such a solar power generation system, grounding faults sometimes occur in the circuitry of the solar cell string due to factors such as aging of the covered components.

[0003] As a known method for detecting ground faults, the self-biasing method is employed. For example, Patent Document 1 discloses a method for detecting the location of a ground fault in a solar cell string using the self-biasing method. Specifically, the positive terminal (P terminal) of the solar cell string is grounded through a sensing resistor, and the voltage across the sensing resistor to ground, i.e., the first voltage, is calculated. Conversely, the negative terminal (N terminal) of the solar cell string is grounded through the sensing resistor, and the voltage across the sensing resistor to ground, i.e., the second voltage, is calculated. Then, the presence and location of a ground fault are detected based on the first and second voltages.

[0004] In recent years, it has been known that tandem (multi-junction) solar cell modules are constructed by stacking photoelectric conversion layers with different band gaps to effectively utilize light across a wide wavelength range and improve the conversion efficiency of solar cell modules. Known photoelectric conversion layers include inorganic thin films such as crystalline silicon substrates and amorphous silicon thin films, organic thin films, and organic-inorganic hybrid thin films (e.g., perovskite thin films). For example, Patent Document 2 discloses a tandem solar cell module constructed by stacking two solar cell sub-modules, each comprising a different photoelectric conversion layer.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-101012

[0006] Patent Document 2: Japanese Patent Application Publication No. 2018-157176

[0007] When applying the above-mentioned series-connected solar cell module to the solar cell string of the above-mentioned solar power generation system, due to the voltage difference between the two types of solar cell sub-modules, it is considered to connect the two types of solar cell sub-modules (2 terminals) in series separately from the multiple series-connected solar cell modules (4 terminals).

[0008] In such a series-connected solar cell module, there are two possibilities for short circuits in the solar cell sub-modules. In a solar power generation system, it is required to have the function of detecting short circuits in multiple series-connected solar cell modules in the solar cell string. Summary of the Invention

[0009] The purpose of this invention is to provide a solar power generation system for detecting short circuits in series-connected solar cell modules and a method for detecting short circuits in a solar power generation system.

[0010] The solar power generation system of the present invention comprises: a solar cell string, which is formed by electrically connecting M four-terminal series-connected solar cell modules, each of the M four-terminal series-connected solar cell modules including a bottom-side solar cell sub-module and a top-side solar cell sub-module (M is an integer greater than or equal to 1); and a short-circuit detection device for detecting a short circuit between the bottom-side solar cell sub-module and the top-side solar cell module of any one of the M series-connected solar cell modules in the solar cell string. In the solar cell string, the M bottom-side solar cell sub-modules of the M series-connected solar cell modules form a bottom-side solar cell string connected in series or parallel, and the M top-side solar cell modules of the M series-connected solar cell modules form a top-side solar cell string connected in series or parallel. The aforementioned short-circuit detection device performs at least one of positive potential terminal measurement and negative potential terminal measurement. The positive potential terminal measurement is performed by electrically connecting the positive potential terminal of the bottom solar cell string to the positive potential terminal or the negative potential terminal of the top solar cell string to measure the potential difference Vps+ between these terminals. The negative potential terminal measurement is performed by electrically connecting the negative potential terminal of the bottom solar cell string to the negative potential terminal or the positive potential terminal of the top solar cell string to measure the potential difference Vps- between these terminals. If at least one of the absolute values ​​of the potential difference Vps+ and the absolute values ​​of the potential difference Vps- is greater than 0V, a short circuit is detected between the bottom solar cell submodule and the top solar cell submodule in any of the M series-connected solar cell modules.

[0011] The short-circuit detection method for a solar power generation system according to this invention includes a solar cell string, which is formed by electrically connecting M four-terminal series-connected solar cell modules. Each of the M four-terminal series-connected solar cell modules includes a bottom-side solar cell sub-module and a top-side solar cell sub-module. In the solar cell string, the M bottom-side solar cell sub-modules of the M series-connected solar cell modules form a bottom-side solar cell string connected in series or parallel, and the M top-side solar cell sub-modules of the M series-connected solar cell modules form a top-side solar cell string connected in series or parallel (M is an integer greater than or equal to 1). The short-circuit detection method performs at least one of positive potential terminal measurement and negative potential terminal measurement. The positive potential terminal measurement involves connecting the positive potential terminal of the bottom-side solar cell string to the top-side solar cell string. The potential difference Vps+ between the positive or negative terminals of the top solar cell string is measured by electrically connecting them. The negative terminal measurement is performed by electrically connecting the negative terminal of the bottom solar cell string to the negative or positive terminal of the top solar cell string to measure the potential difference Vps- between them. If at least one of the absolute values ​​of the potential difference Vps+ and Vps- is greater than 0V, a short circuit between the bottom solar cell submodule and the top solar cell submodule in any of the M series-connected solar cell modules is detected.

[0012] According to the present invention, a short circuit in a series-connected solar cell module can be detected in a solar power generation system. Attached Figure Description

[0013] Figure 1 This is a schematic diagram showing the configuration of the solar power generation system according to the first embodiment.

[0014] Figure 2 It means Figure 1 A schematic diagram of the configuration of the short-circuit detection device 32 in the power regulator 30 of the solar power generation system 1 shown.

[0015] Figure 3 It means Figure 1 A diagram of solar cell strings in a solar power generation system.

[0016] Figure 4 It means Figure 1 A diagram of solar cell strings in a solar power generation system.

[0017] Figure 5 It means Figure 1 A diagram of solar cell strings in a solar power generation system.

[0018] Figure 6 It means Figure 1 A diagram of solar cell strings in a solar power generation system.

[0019] Figure 7 This is a schematic diagram showing the configuration of the solar power generation system according to the second embodiment.

[0020] Figure 8 It means Figure 7 A diagram of solar cell strings in a solar power generation system.

[0021] Figure 9 It means Figure 7 A diagram of solar cell strings in a solar power generation system. Detailed Implementation

[0022] Hereinafter, an example of an embodiment of the present invention will be described with reference to the accompanying drawings. Furthermore, the same or equivalent parts will be labeled with the same reference numerals in all the drawings. Additionally, for convenience, there are cases where shaded lines, component reference numerals, etc., are omitted; however, in such cases, refer to the other drawings.

[0023] [First Implementation Method]

[0024] (Solar power generation system)

[0025] Figure 1 This is a schematic diagram illustrating the configuration of the solar power generation system according to the first embodiment. (Example) Figure 1 As shown, the solar power generation system 1 includes a solar cell string 10 and a power conditioning system (PCS) 30.

[0026] The solar cell string 10 includes M solar cell modules 20 (M is an integer greater than or equal to 1) electrically connected between two positive potential terminals P and two negative potential terminals N. Furthermore, hereinafter, when referring to each of the M solar cell modules 20, it is sometimes referred to as the m-th solar cell module from the positive potential terminal P side of the solar cell string 10 (m is an integer greater than or equal to 1 and less than or equal to M).

[0027] Solar cell module 20 is a series-connected solar cell module formed by stacking a bottom-side solar cell sub-module 22 and a top-side solar cell sub-module 24. It is a 4-terminal solar cell module. In solar cell module 20, the bottom-side solar cell sub-module 22 and the top-side solar cell module 24 are electrically insulated.

[0028] In the solar cell string 10, M bottom solar cell sub-modules 22 of the M solar cell modules 20 form a bottom solar cell string 12 connected in series between a positive potential terminal P and a negative potential terminal N, and M top solar cell sub-modules 24 of the M solar cell modules 20 form a top solar cell string 14 connected in series between another positive potential terminal P and another negative potential terminal N.

[0029] The bottom solar cell submodule 22 includes multiple solar cell units (or solar cell panels) connected in series, and the top solar cell submodule 24 includes multiple solar cell units (or solar cell panels) connected in series.

[0030] Examples of solar cell units in the bottom-side solar cell submodule 22 and the top-side solar cell submodule 24 include thin-film solar cell units such as amorphous silicon or perovskite solar cells, which use inorganic semiconductor thin films, organic semiconductor thin films, or organic-inorganic hybrid semiconductor thin films as photoelectric conversion layers, or crystalline silicon solar cell units that use crystalline silicon substrates as photoelectric conversion layers. For example, if the bottom-side solar cell submodule 22 is a module that includes crystalline silicon solar cell units and the top-side solar cell submodule 24 is a module that includes perovskite solar cell units, then a wider wavelength range of light can be effectively utilized, which is preferable.

[0031] The power conditioner 30 converts the DC power from the bottom solar cell string 12 in the solar cell string 10 into the desired AC or DC power, and converts the DC power from the top solar cell string 14 in the solar cell string 10 into the desired AC or DC power, and synthesizes these converted powers. The power conditioner 30 may have a Maximum Power Point Tracking (MPPT) function that tracks the optimal operating point (maximum power point) of the output power of the bottom solar cell string 12 in the solar cell string 10, or it may have a Maximum Power Point Tracking (MPPT) function that tracks the optimal operating point (maximum power point) of the output power of the top solar cell string 14 in the solar cell string 10. The power conditioner 30 includes a short-circuit detection device 32.

[0032] Figure 2 It means Figure 1 A schematic diagram of the configuration of the short-circuit detection device 32 in the power regulator 30 of the solar power generation system 1 shown. Figure 2The short-circuit detection device 32 shown detects the presence or absence of a short circuit between the bottom solar cell sub-module 22 and the top solar cell sub-module 24 in any one of the solar cell modules 20 of the solar cell string 10. Furthermore, the short-circuit detection device 32 determines (infers) the location of the short circuit between the bottom solar cell sub-module 22 and the top solar cell module 24 in any one of the solar cell modules 20 of the solar cell string 10. The short-circuit detection device 32 includes two ground fault detection circuits, a voltmeter Vps, a control unit 35, a storage unit 36, a communication unit 37, and a display unit 38.

[0033] The two ground fault detection circuits are, for example, ground fault detection circuits using a known self-biasing method (see, for example, Patent Document 1). Alternatively, the two ground fault detection circuits in the short-circuit detection device 32 can also utilize the ground fault detection circuit provided in the power regulator 30.

[0034] For example, a ground fault detection circuit includes: a resistor R having one end connected to the positive potential terminal P of the bottom solar cell string 12 in the solar cell string 10; a resistor R having one end connected to the negative potential terminal N of the bottom solar cell string 12 in the solar cell string 10; a voltmeter Vs; and a switch SW that selectively connects the voltmeter Vs to either of the other ends of the two resistors R. Thus, the ground fault detection circuit grounds the positive potential terminal P of the bottom solar cell string 12 through the resistor R and calculates the voltage to ground across the resistor R, i.e., voltage Vs+. Similarly, the ground fault detection circuit grounds the negative potential terminal N of the bottom solar cell string 12 through the resistor R and calculates the voltage to ground across the resistor R, i.e., voltage Vs-. Then, the ground fault detection circuit detects the presence and location of a ground fault in the bottom solar cell string 12 based on voltages Vs+ and Vs-.

[0035] Similarly, for example, another ground fault detection circuit includes: a resistor R having one end connected to the positive potential terminal P of the top solar cell string 14 in the solar cell string 10; a resistor R having one end connected to the negative potential terminal N of the top solar cell string 14 in the solar cell string 10; a voltmeter Vp; and a switch SW that selectively connects the voltmeter Vp to either of the other ends of the two resistors R. Thus, the ground fault detection circuit grounds the positive potential terminal P of the top solar cell string 14 through the resistor R and calculates the voltage to ground across the resistor R, i.e., voltage Vp+. Additionally, the ground fault detection circuit grounds the negative potential terminal N of the top solar cell string 14 through the resistor R and calculates the voltage to ground across the resistor R, i.e., voltage Vp-. Then, the ground fault detection circuit detects the presence and location of a ground fault in the top solar cell string 14 based on voltages Vp+ and Vp-.

[0036] The control unit 35 performs overall control of the short-circuit detection device 32. The control unit 35 of the short-circuit detection device 32 may be composed of a processing unit such as a CPU (Central Processing Unit), DSP (Digital Signal Processor), or FPGA (Field-Programmable Gate Array). The various functions of the control unit 35 of the short-circuit detection device 32 are implemented, for example, by executing predefined software (programs, application programs) stored in the storage unit 36. The various functions of the control unit 35 of the short-circuit detection device 32 can be implemented through a combination of hardware and software, or solely through hardware (electronic circuitry).

[0037] The storage unit 36 ​​stores the prescribed software (program, application program) executed by the control unit 35 of the short-circuit detection device 32. Additionally, the storage unit 36 ​​stores the measured voltage values ​​of the bottom-side solar cell sub-module 22 and the top-side solar cell sub-module 24 in each solar cell module 20, which have been measured beforehand. Furthermore, the storage unit 36 ​​stores the number M of the solar cell modules 20. The storage unit 36 ​​is composed of rewritable memory such as ROM (Read Only Memory), HDD (Hard Disk Drive), or SSD (Solid State Drive).

[0038] The communication section 37 is an interface for communicating information with the outside world in accordance with communication standards such as wired LAN and wireless LAN.

[0039] Display unit 38 is, for example, a notification unit that notifies maintenance managers of information. Display unit 38 may be composed of, for example, a liquid crystal display or an organic EL display.

[0040] In addition, a portion of the short circuit detection device 32, such as a portion of the control unit 35, storage unit 36, communication unit 37, and display unit 38, may also be disposed outside the short circuit detection device 32, such as in the power regulator 30 or a host device connected to the power regulator 30.

[0041] (Short-circuit detection method)

[0042] The following is for reference Figures 1-4 The short-circuit detection method for the solar cell string 10 based on the short-circuit detection device 32 in the short-circuit detection method of the solar power generation system according to the first embodiment will be described. Figure 3 and Figure 4 It means Figure 1 A diagram of solar cell strings in a solar power generation system.

[0043] First, such as Figure 3 As shown, the short-circuit detection device 32 connects the positive potential terminal P of the bottom solar cell string 12 and the positive potential terminal P of the top solar cell string 14 in the solar cell string 10 via a resistor R and a voltmeter Vps to measure the potential difference Vps+ between these terminals P and P (positive potential terminal measurement).

[0044] Next, as Figure 4 As shown, the short-circuit detection device 32 connects the negative potential terminal N of the bottom solar cell string 12 and the negative potential terminal N of the top solar cell string 14 in the solar cell string 10 via a resistor R and a voltmeter Vps to measure the potential difference Vps- (negative potential terminal measurement) between these terminals N and N. Furthermore, if it is possible to detect the presence or absence of a short circuit but not the location of the short circuit, it is sufficient to perform at least one of the positive potential terminal measurement and the negative potential terminal measurement.

[0045] Next, the short-circuit detection device 32 detects the presence or absence of a short circuit between the bottom solar cell sub-module 22 and the top solar cell sub-module 24 in any one of the solar cell modules 20 of the solar cell string 10 based on at least one of the potential difference Vps+ and the potential difference Vps-. Specifically, if at least one of the absolute values ​​of the potential difference Vps+ and the potential difference Vps- is 0V, the short-circuit detection device 32 determines that there is no short circuit between the bottom solar cell sub-module 22 and the top solar cell module 24 in any one of the solar cell modules 20 in the solar cell string 10.

[0046] On the other hand, if at least one of the absolute values ​​of the potential difference Vps+ and the absolute values ​​of the potential difference Vps- is greater than 0V, the short circuit detection device 32 detects a short circuit between the bottom solar cell sub-module 22 and the top solar cell sub-module 24 in any one of the solar cell modules 20 of the solar cell string 10.

[0047] Here, for example, if the voltage of each solar cell module 20 is known in advance through factory inspection, the location of a short circuit in the solar cell string 10 can be deduced. Specifically, the short circuit detection device 32 determines the location of a short circuit in the solar cell string 10 based on the potential difference Vps+, the potential difference Vps-, and the measured values ​​of the voltages of the bottom solar cell sub-module 22 and the top solar cell sub-module 24 in each solar cell module 20, which are stored in advance in the storage unit 36.

[0048] On the other hand, even without knowing the voltage of each solar cell module 20, the location of a short circuit in the solar cell string 10 can be inferred from the ratio of the absolute value of the potential difference Vps+ to the absolute value of the potential difference Vps-. Specifically, the short circuit detection device 32 can also calculate the ratio of the absolute value of the potential difference Vps+ to the absolute value of the potential difference Vps-, and output the calculated ratio as a reference for the short circuit location in the solar cell string 10 to the maintenance manager. The calculated ratio can be transmitted by the communication unit 37 or displayed by the display unit 38.

[0049] The following uses Figure 3 and Figure 4 Let's illustrate with a specific example. Figure 3 and Figure 4 In this configuration, the number M of solar cell modules 20 in solar cell string 10 is 5. Specifically, the number M of bottom solar cell sub-modules 22 in bottom solar cell string 12 is 5, and the number M of top solar cell modules 24 in top solar cell string 14 is 5. Furthermore, the bottom solar cell sub-module 22 and the top solar cell module 24 in the second solar cell module 20 starting from the positive potential terminal P side of solar cell string 10 are short-circuited.

[0050] In addition, the voltages of the bottom solar cell sub-module 22 and the top solar cell sub-module 24 in the m-th solar cell module 20, starting from the positive potential terminal P side of the solar cell string 10, are as follows.

[0051] m=1

[0052] The voltage of the top-side solar cell sub-module 24 is 33V.

[0053] The voltage of the bottom solar cell sub-module 22 is 10V.

[0054] m=2

[0055] The voltage of the top-side solar cell module 24 is 20V / 10V ( / indicates a short circuit position).

[0056] The voltage of the bottom solar cell module 22 is 4V / 8V ( / indicates a short circuit position).

[0057] m=3

[0058] The voltage of the top-side solar cell sub-module 24 is 31V.

[0059] The voltage of the bottom solar cell sub-module 22 is 11V.

[0060] m=4

[0061] The voltage of the top-side solar cell sub-module 24 is 34V.

[0062] The voltage of the bottom solar cell sub-module 22 is 13V.

[0063] m=5

[0064] The voltage of the top-side solar cell sub-module 24 is 32V.

[0065] The voltage of the bottom solar cell sub-module 22 is 11V.

[0066] according to Figure 3 and Figure 4 The potential difference Vps+ and potential difference Vps- are measured as follows.

[0067] Vps+=(33V+20V)-(10V+4V)=39V

[0068] Vps-=(-32V-34V-31V-10V)-(-11V-13V-11V-8V)=-64V

[0069] Therefore, the absolute values ​​of the potential difference Vps+ and Vps- are greater than 0V, so the short circuit detection device 32 detects a short circuit between the bottom solar cell sub-module 22 and the top solar cell sub-module 24 in any one of the solar cell modules 20 of the solar cell string 10.

[0070] Here, for example, if the voltage of each solar cell module 20 is known in advance through factory inspection, the location of a short circuit in the solar cell string 10 can be deduced. Specifically, based on the measured voltage values ​​of the bottom solar cell sub-module 22 and the top solar cell sub-module 24 in each solar cell module 20 stored in the storage unit 36 ​​in advance, the location of a short circuit in the m=2 solar cell modules 20 of the solar cell string 10 can be deduced based on the absolute value of the potential difference Vps+. Furthermore, based on the measured voltage values ​​of the bottom solar cell sub-module 22 and the top solar cell sub-module 24 in each solar cell module 20 stored in the storage unit 36 ​​in advance, the location of a short circuit in the m=2 solar cell modules 20 of the solar cell string 10 can be deduced based on the absolute value of the potential difference Vps-. In this way, the short circuit detection device 32 determines the location of a short circuit in the solar cell string 10. Moreover, the short circuit detection device 32 can also determine the short circuit location of a unit within the solar cell module 20 of the solar cell string 10.

[0071] On the other hand, without knowing the voltage of each solar cell module 20, the location of a short circuit in the solar cell string 10 can be inferred from the ratio of the absolute value of the potential difference Vps+ to the absolute value of the potential difference Vps-. Specifically, the short circuit detection device 32 calculates the ratio of the absolute value of the potential difference Vps+ to the absolute value of the potential difference Vps-: |Vps+| / (|Vps+|+|Vps-|). For example, if it is assumed that the voltages of each solar cell module 20 are approximately the same, it can be inferred that:

[0072] • When this ratio is less than 0.2, a short circuit exists in the solar cell module 20 with m=1.

[0073] • When the ratio is greater than or equal to 0.2 and less than 0.4, a short circuit exists in the solar cell module 20 with m = 2.

[0074] • When the ratio is greater than or equal to 0.4 but less than 0.6, a short circuit exists in the solar cell module 20 with m=3.

[0075] • When the ratio is greater than or equal to 0.6 but less than 0.8, a short circuit exists in the solar cell module 20 with m=4.

[0076] When the ratio is 0.8 or higher but less than 1.0, a short circuit exists in the solar cell module 20 with m = 5. In this way, the location of the short circuit in the solar cell string 10 can be deduced. Furthermore, the location of the short circuit within the cells of the solar cell module 20 in the solar cell string 10 can also be deduced.

[0077] In this way, the short-circuit detection device 32 can also output the calculated ratio |Vps+| / (|Vps+|+|Vps-|) as a reference for the short-circuit position in the solar cell string 10 to the maintenance manager. Furthermore, the short-circuit detection device 32 can also output the calculated ratio |Vps+| / (|Vps+|+|Vps-|) as a percentage.

[0078] Similarly, the short-circuit detection device 32 can also calculate the ratio of the absolute value of the potential difference Vps+ to the absolute value of the potential difference Vps-, |Vps-| / (|Vps+|+|Vps-|), and output the calculated ratio |Vps-| / (|Vps+|+|Vps-|) as a reference for the short-circuit position in the solar cell string 10 to the maintenance manager. Furthermore, the short-circuit detection device 32 can also output the calculated ratio |Vps-| / (|Vps+|+|Vps-|) as a percentage.

[0079] According to the above-described short-circuit detection method for solar cell string 10 based on short-circuit detection device 32, it is possible to detect not only 1-point short circuit but also 2-point short circuit. Figure 5and Figure 6 It means Figure 1 A diagram showing the solar cell strings in a solar power generation system. Figure 5 and Figure 6 In Figure 3 and Figure 4 Based on this, the bottom solar cell sub-module 22 and the top solar cell module 24 in the fifth solar cell module 20, starting from the positive potential terminal P side of the solar cell string 10, are also short-circuited. The voltages of the bottom solar cell sub-module 22 and the top solar cell module 24 in the solar cell module 20 with m=5 are as follows.

[0080] m=5

[0081] The voltage of the top-side solar cell module 24 is 7V / 25V ( / indicates a short circuit position).

[0082] The voltage of the bottom solar cell module 22 is 9V / 2V ( / indicates a short circuit position).

[0083] according to Figure 5 and Figure 6 The potential difference Vps+ and potential difference Vps- are measured as follows.

[0084] Vps(+)=(33V+20V)-(10V+4V)=39V

[0085] Vps(-)=(-25V)-(-2V)=-23V

[0086] Here, for example, if the number M of solar cell modules 20 and the voltage of each solar cell module 20 are known in advance through factory inspection, the presence or absence of a two-point short circuit in the solar cell string 10 can be detected. Specifically, based on the number M of solar cell modules 20 stored in advance in the storage unit 36 ​​and the measured values ​​of the voltages of the bottom-side solar cell sub-modules 22 and the top-side solar cell sub-modules 24 in each solar cell module 20, if the sum of the absolute values ​​of the potential difference Vps+ and the absolute values ​​of the potential difference Vps- is less than the sum of the measured values ​​of m = 1 to 5, the short circuit detection device 32 can detect a two-point short circuit in the solar cell string 10.

[0087] Furthermore, based on the measured voltage values ​​of the bottom-side solar cell sub-modules 22 and top-side solar cell sub-modules 24 in each solar cell module 20 pre-stored in the storage unit 36, the device can infer the location of a first short circuit in the solar cell module 20 with m=2 in the solar cell string 10 based on the absolute value of the potential difference Vps+. Additionally, based on the measured voltage values ​​of the bottom-side solar cell sub-modules 22 and top-side solar cell sub-modules 24 in each solar cell module 20 pre-stored in the storage unit 36, the device can infer the location of a second short circuit in the solar cell module 20 with m=5 in the solar cell string 10 based on the absolute value of the potential difference Vps-. In this way, the short circuit detection device 32 determines the locations of two short circuits in the solar cell string 10. Furthermore, the short circuit detection device 32 can also determine the locations of two short circuits within the cells of the solar cell module 20 in the solar cell string 10.

[0088] As explained above, according to the solar power generation system 1 and the short circuit detection method of the solar power generation system of the first embodiment, it is possible to detect whether there is a short circuit between the bottom solar cell sub-module 22 and the top solar cell sub-module 24 in any one of the multiple series-connected solar cell modules 20 of the solar cell string 10, and to determine (infer) the location of the short circuit.

[0089] [Second Implementation]

[0090] (Solar power generation system)

[0091] In the first embodiment, the configuration of connecting M top-side solar cell sub-modules 24 of the M solar cell modules 20 in the top-side solar cell string 14 of the solar cell string 10 in series was described. In the second embodiment, the configuration of connecting M top-side solar cell sub-modules 24 of the M solar cell modules 20 in the top-side solar cell string 14 of the solar cell string 10 in parallel was described. Furthermore, the configuration of connecting M bottom-side solar cell sub-modules 22 of the M solar cell modules 20 in the bottom-side solar cell string 12 of the solar cell string 10 in parallel is omitted from the description, but it can also be considered in the same way.

[0092] Figure 7 This is a schematic diagram illustrating the configuration of the solar power generation system according to the second embodiment. Figure 1 Compared to the solar power generation system 1 of the first embodiment shown, Figure 7 The connection configuration of the top solar cell string 14 in the solar cell string 10 of the second embodiment of the solar power generation system 1 is different. Other configurations of the solar power generation system 1 in the second embodiment are the same as those in the solar power generation system 1 of the first embodiment.

[0093] like Figure 7 As shown, in the solar cell string 10, M top-side solar cell sub-modules 24 of the M solar cell modules 20 constitute a top-side solar cell string 14 connected in parallel between another positive potential terminal P and another negative potential terminal N.

[0094] For example, perovskite-based and other thin-film solar cell submodules are composed of multiple thin-film solar cell units. These units are segmented on a substrate in a first direction (integration direction) and extended along a second direction intersecting the first direction, and are integrated by being connected in series. In this case, the solar cell submodule has a relatively high voltage, and therefore, sometimes the solar cell submodules are connected in parallel in a solar cell string.

[0095] (Short-circuit detection method)

[0096] In the second embodiment, similar to the first embodiment, a short circuit in the solar cell string 10 can be detected by the short circuit detection device 32. Figure 8 and Figure 9 It means Figure 7 A diagram of solar cell strings in a solar power generation system.

[0097] First, such as Figure 8 As shown, the short-circuit detection device 32 connects the positive potential terminal P of the bottom solar cell string 12 and the positive potential terminal P of the top solar cell string 14 in the solar cell string 10 via a resistor R and a voltmeter Vps to measure the potential difference Vps+ between these terminals P and P (positive potential terminal measurement).

[0098] Next, as Figure 9 As shown, the short-circuit detection device 32 connects the negative potential terminal N of the bottom solar cell string 12 and the negative potential terminal N of the top solar cell string 14 in the solar cell string 10 via a resistor R and a voltmeter Vps to measure the potential difference Vps- (negative potential terminal measurement) between these terminals N and N. Furthermore, in the case of only detecting the presence or absence of a short circuit as described above, it is sufficient to perform at least one of the positive potential terminal measurement and the negative potential terminal measurement.

[0099] Next, the short-circuit detection device 32 detects the presence or absence of a short circuit between the bottom solar cell sub-module 22 and the top solar cell sub-module 24 in any one of the solar cell modules 20 of the solar cell string 10 based on at least one of the potential difference Vps+ and the potential difference Vps-. Specifically, if at least one of the absolute values ​​of the potential difference Vps+ and the potential difference Vps- is 0V, the short-circuit detection device 32 determines that there is no short circuit between the bottom solar cell sub-module 22 and the top solar cell module 24 in any one of the solar cell modules 20 of the solar cell string 10.

[0100] On the other hand, if at least one of the absolute values ​​of the potential difference Vps+ and the absolute values ​​of the potential difference Vps- is greater than 0V, the short circuit detection device 32 detects a short circuit between the bottom solar cell sub-module 22 and the top solar cell sub-module 24 in any one of the solar cell modules 20 of the solar cell string 10.

[0101] according to Figure 8 and Figure 9 The potential difference Vps+ and potential difference Vps- are measured as follows.

[0102] Vps+=(20V)-(10V+4V)=6V

[0103] Vps-=(-10V)-(-11V-13V-11V-8V)=33V

[0104] Therefore, the absolute values ​​of the potential difference Vps+ and Vps- are greater than 0V, so the short circuit detection device 32 detects a short circuit between the bottom solar cell sub-module 22 and the top solar cell sub-module 24 in any one of the solar cell modules 20 of the solar cell string 10.

[0105] In this way, even when multiple series-connected solar cell modules 20 in the solar cell string 10 are connected in parallel, it is possible to detect whether there is a short circuit between the bottom solar cell sub-module 22 and the top solar cell sub-module 24 in any one of the multiple series-connected solar cell modules 20 in the solar cell string 10.

[0106] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments and various modifications and variations are possible. For example, in the above embodiments, the short-circuit detection device 32 and the short-circuit detection method exemplify a method in which the positive potential terminal P of the bottom solar cell string 12 and the positive potential terminal P of the top solar cell string 14 in the solar cell string 10 are electrically connected via a resistor R and a voltmeter Vps to measure the potential difference Vps+ (positive potential terminal measurement) between these terminals P and P. However, the present invention is not limited to this, and the short-circuit detection device 32 and the short-circuit detection method may also involve a method in which the positive potential terminal P of the bottom solar cell string 12 and the negative potential terminal N of the top solar cell string 14 in the solar cell string 10 are electrically connected via a resistor R and a voltmeter Vps to measure the potential difference Vps+ (positive potential terminal measurement) between these terminals P and N.

[0107] Furthermore, in the above embodiments, an example is illustrated in the short-circuit detection device 32 and the short-circuit detection method, in which the negative potential terminal N of the bottom solar cell string 12 and the negative potential terminal N of the top solar cell string 14 in the solar cell string 10 are electrically connected via a resistor R and a voltmeter Vps to measure the potential difference Vps- (negative potential terminal measurement) between these terminals N and N. However, the present invention is not limited to this, and the short-circuit detection device 32 and the short-circuit detection method may also measure the potential difference Vps- (negative potential terminal measurement) between these terminals N and P via a resistor R and a voltmeter Vps.

[0108] Even in these methods, as described above, it is possible to detect the presence or absence of a short circuit between the bottom solar cell submodule 22 and the top solar cell submodule 24 in any one of the multiple series-connected solar cell modules 20 of the solar cell string 10 based on at least one of the potential difference Vps+ and the potential difference Vps-, and to determine (infer) the location of the short circuit.

[0109] Explanation of reference numerals in the attached figures

[0110] 1…Solar power generation system; 10…Solar cell string; 12…Bottom-side solar cell string; 14…Top-side solar cell string; 20…Solar cell module; 22…Bottom-side solar cell sub-module; 24…Top-side solar cell sub-module; 30…Power regulator; 32…Short circuit detection device; 35…Control unit; 36…Storage unit; 37…Communication unit; 38…Display unit; R…Resistor; SW…Switch.

Claims

1. A solar power generation system, characterized in that, have: A solar cell string is formed by electrically connecting M four-terminal series-connected solar cell modules. Each of the M four-terminal series-connected solar cell modules includes a bottom-side solar cell sub-module and a top-side solar cell sub-module. Here, M is an integer greater than or equal to 1. and A short-circuit detection device detects a short circuit between the bottom-side solar cell submodule and the top-side solar cell module in any one of the M series-connected solar cell modules in the solar cell string. In the solar cell string, The M bottom-side solar cell sub-modules in the M series-connected solar cell modules constitute a bottom-side solar cell string connected in series or parallel. The M top-side solar cell sub-modules in the M series-connected solar cell modules constitute a top-side solar cell string connected in series or parallel. The short-circuit detection device performs at least one of the following measurements: positive potential terminal measurement and negative potential terminal measurement. The positive potential terminal measurement is performed by electrically connecting the positive potential terminal of the bottom solar cell string to the positive potential terminal or negative potential terminal of the top solar cell string to measure the potential difference Vps+ between these terminals. The negative potential terminal measurement is performed by electrically connecting the negative potential terminal of the bottom solar cell string to the negative potential terminal or positive potential terminal of the top solar cell string to measure the potential difference Vps between these terminals. If at least one of the absolute values ​​of the potential difference Vps+ and Vps- is greater than 0V, a short circuit between the bottom solar cell submodule and the top solar cell submodule in any of the M series-connected solar cell modules is detected.

2. The solar power generation system according to claim 1, characterized in that, The short-circuit detection device has a storage unit that stores the measured values ​​of the voltages of the M bottom-side solar cell sub-modules and the M top-side solar cell sub-modules, which have been measured in advance. The short-circuit detection device determines the location of the short circuit in the solar cell string based on the potential difference Vps+, the potential difference Vps-, and the measured values ​​pre-stored in the storage unit.

3. The solar power generation system according to claim 1, characterized in that, The short-circuit detection device determines the location of a short circuit in the solar cell string based on the ratio of the absolute value of the potential difference Vps+ to the absolute value of the potential difference Vps-.

4. A short-circuit detection method for a solar power generation system, wherein the solar power generation system comprises a solar cell string, the solar cell string being formed by electrically connecting M four-terminal series-connected solar cell modules, each of the M four-terminal series-connected solar cell modules including a bottom-side solar cell sub-module and a top-side solar cell sub-module. In the solar cell string, The M bottom-side solar cell sub-modules in the M series-connected solar cell modules constitute a bottom-side solar cell string connected in series or parallel. The M top-side solar cell sub-modules in the M series-connected solar cell modules constitute a top-side solar cell string connected in series or parallel. The short-circuit detection method for the solar power generation system is characterized by the following: Here, M is an integer greater than or equal to 1. Perform at least one of the measurements of the positive potential terminal and the negative potential terminal. The positive potential terminal measurement is performed by electrically connecting the positive potential terminal of the bottom solar cell string to the positive potential terminal or negative potential terminal of the top solar cell string to measure the potential difference Vps+ between these terminals. The negative potential terminal measurement is performed by electrically connecting the negative potential terminal of the bottom solar cell string to the negative potential terminal or positive potential terminal of the top solar cell string to measure the potential difference Vps between these terminals. If at least one of the absolute values ​​of the potential difference Vps+ and Vps- is greater than 0V, a short circuit between the bottom solar cell submodule and the top solar cell submodule in any of the M series-connected solar cell modules is detected.

5. The short-circuit detection method for a solar power generation system according to claim 4, characterized in that, The system stores the pre-measured voltage values ​​of the M bottom-side solar cell sub-modules and the M top-side solar cell sub-modules. The location of the short circuit in the solar cell string is determined based on the potential difference Vps+, the potential difference Vps-, and the pre-stored measured values.

6. The short-circuit detection method for a solar power generation system according to claim 4, characterized in that, The location of the short circuit in the solar cell string is determined based on the ratio of the absolute value of the potential difference Vps+ to the absolute value of the potential difference Vps-.

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