JP2019122056A - Solar cell diagnostic device, solar cell diagnostic method, and solar power generation system - Google Patents

Abstract

To provide a solar cell diagnostic device, a solar cell diagnostic method, and a solar power generation system capable of diagnosing failures of a solar cell accurately even under output suppression control.SOLUTION: A solar cell diagnostic device stores, in advance, reference table 601 for storing combinations of a ratio J between a short circuit current and an operating current at a plurality of operating points of a solar battery cell, a slope δI/δV of current-voltage characteristics and a slope δP/δV of power-voltage characteristics, and finds the operating point of the solar battery cell (S68) based on a coincidence with any of the combinations of a ratio between the short-circuit current and the operating current in the solar battery cell to be set (S61), the slope δI/δV of the current-voltage characteristics calculated based on the ratio to be set and the measured operating current Iand operating voltage Vof the solar battery cell, and the slope δP/δV of the power-voltage characteristics, and the combinations at multiple operating points stored in the reference table.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a solar cell diagnostic device, a solar cell diagnostic method, and a solar power generation system.

  In Patent Document 1, in order to determine an abnormality such as deterioration or failure of a solar cell, the electric output value of the solar cell in a state that can be regarded as fine weather is accumulated, and the electric output value of the solar cell is almost the same. The method of evaluating the power generation performance of a photovoltaic power plant is described by comparing conditions. According to Patent Document 2, power generation amount higher than power generation equivalent amount in a specific evaluation time zone of a sample period which is a period serving as a reference of judgment with respect to power generation amount measured from a measuring instrument provided in a solar power generation system. A method is disclosed for extracting a considerable amount and determining a failure with the upper generation equivalent amount as a reference value.

JP, 2016-54632, A JP 2012-114108 A

  As a large-scale solar power plant has been introduced by measures based on the FIT (Feed-in Tariffs) system, the power plant of solar power plants is going to be controlled for system stabilization. In addition, there are many introductions of overloaded solar power plants in order to secure the daily power output. For this reason, it is not uncommon for a solar power plant where the time zone for operation with the generated power being restricted to a certain level or less reaches more than half a day. In a time zone in which the power is restricted to a certain level or less, that is, under power suppression control, the solar cell module is operated at an operating point out of the operating point (maximum power point) where the maximum power can be obtained. For this reason, degradation can not be determined even when compared with the reference power during output suppression. In addition, one measuring instrument such as a pyranometer installed at a power generation site is generally one at a large site, and can not be treated as a reference in consideration of fluctuations and the like.

  Furthermore, as the introduction of VPP (Virtual Power Plant) progresses, it is considered that the need for grasping how much the photovoltaic power generation with reduced output can be generated is also increasing.

  A solar cell diagnostic device that diagnoses a solar cell having a solar cell module in which a plurality of solar cells are connected in series according to an embodiment of the present invention includes a processor, a memory, and a plurality of operating points of the solar cells. Reference table storing combinations of short-circuit current and operating current ratio, slope of current-voltage characteristics and slope of power-voltage characteristics, and aid to store a solar cell diagnostic program read into a memory and executed by a processor The solar cell diagnostic program has an operating point detecting unit, and the operating point detecting unit has a ratio of the short circuit current to the operating current of the set solar battery cell, the set ratio and the set solar battery cell. The combination of the slope of the current-voltage characteristics and the slope of the power-voltage characteristics calculated based on the measured operating current and operating voltage, and stored in the reference table It was based on a match between any combination of a plurality of operating points to determine the operating point of the solar cell.

  Other problems and novel features will be apparent from the description of the present specification and the accompanying drawings.

  It is possible to diagnose the failure of the solar cell even under the output suppression control, and the diagnosis with high accuracy becomes possible.

It is a schematic block diagram of a solar energy power generation system. It is an example of the time transition of the observed value of DC power. It is a current-voltage characteristic of the solar cell string group 1 in the time zone 201. It is a current-voltage characteristic of solar cell string group 1 in time slot 202. It is a figure which shows the current-voltage characteristic of a photovoltaic cell. It is a figure which shows the electric power-voltage characteristic of a photovoltaic cell. It is a figure which shows the equivalent circuit of a photovoltaic cell. It is a first flowchart for obtaining the ratio J. It is the 2nd flow chart which asks for ratio J. It is a figure which shows the temperature characteristic of the operating voltage of a photovoltaic cell. It is a failure diagnosis flow of a solar cell module. It is an example of GUI which displays the diagnostic result of a solar cell module. It is an example of GUI which displays the diagnostic result of a solar cell module. It is an example of hardware constitutions of an application server (solar cell diagnostic device).

  FIG. 1 is a diagram showing the configuration of a solar power generation system. The solar power generation system includes a solar cell string 1b in which a plurality of solar cell modules 1a are connected in series, a junction box 2 that bundles a plurality of solar cell strings 1b, a power conditioner 3 that bundles a plurality of junction boxes 2, a HUB 5, a PLC (Programmable Logic Controller 6 and transmission device 7. Data from the transmission device 7 is transmitted to the data center 4 via the network 8a. In the data center 4, the transmitted data is stored in the data server 41 through the physical switch 45 and the relay device 44. The application server 42 takes out stored data from the data server 41 and executes diagnosis and the like. The Web server 43 displays the diagnostic result and the like executed by the application server 42, and the diagnostic result can be confirmed by the PC terminal 9a and the portable terminal 9b through the firewall 46 and the network 8b.

  The junction box 2 is provided with a backflow prevention diode 21 for preventing current from flowing into the solar cell string 1b, and a fuse 22 and a circuit breaker 23 for interrupting the current path if a large current should flow. ing. The sum of the plurality of solar cell strings bundled by the connection box 2 is connected to one power conditioner 3. Here, a group of a plurality of solar cell strings connected to one power conditioner 3 is expressed as a solar cell string group 1.

The power conditioner 3 includes a current measurement device 31 that measures the DC current I _op of the solar cell string group 1 and a voltage measurement device 32 that measures the DC voltage V _op . The output of the solar cell string group 1 is controlled by the control unit 35 based on the control waveform generated by the control waveform generation unit 34 based on the DC current I _op sampled by the sampling processing unit 33 and the DC voltage V _op. Ru. The control unit 35 performs maximum power point tracking (MPPT) control or output suppression control. The MPPT control is control to extract the maximum power from the solar cell string group 1, and the output suppression control is control to maintain the power extracted from the solar cell string group 1 at a predetermined constant power. The direct current voltage and the direct current, which are boosted and lowered by the control unit 35, are converted into an alternating current by the direct current to alternating current conversion unit 36 and linked to the system. In addition, the value of the direct current (PCS current) I _op sampled by the sampling processing unit 33 and the value of the direct current voltage (PCS voltage) V _op are signals necessary for transmitting to the data center 4 in the signal conversion transmission device 37 A conversion is made.

  FIG. 2 shows an example of the time transition of the observed value of DC power output from the power conditioner 3 on a certain sunny day. In this example, while the MPPT control is performed in the time zone 201, the output suppression control is performed in the time zone 202, and the power output from the power conditioner 3 is kept constant. For the DC power transition (observed value) 210 indicated by a thick line, a DC power transition (predicted value) 211 that would have been output if MPPT control was performed in the time zone 202 is indicated by a dotted line. In the time zone 202, the difference 212 between the DC power transition (observed value) 210 and the DC power transition (predicted value) 211 is potential power.

  The current-voltage characteristic (I-V characteristic) of the solar cell string group 1 in the time zone 201 is shown to FIG. 3A. The IV characteristic I51 in low solar radiation and the I-V characteristic I52 in high solar radiation are shown. In the time zone 201, MPPT control is performed, and the operating point I 51 o and the operating point I 52 o are the operating points of the power conditioner 3 under the MPPT control. Under MPPT control, the ratio of the operating current I51a to the short circuit current I51b in low solar radiation and the ratio of the operating current I52a to the short circuit current I52b in high solar radiation are equal.

  On the other hand, the IV characteristic of the solar cell string group 1 in the time slot 202 is shown in FIG. 3B. The IV characteristic I53 in low solar radiation and the I-V characteristic I54 in high solar radiation are shown. The output suppression control is performed in the time zone 202, and the operating point I53o and the operating point I54o are operating points of the power conditioner 3 under the output suppression control. Under output suppression control, the ratio of the operating current I53a to the short circuit current I53b in low solar radiation and the ratio of the operating current I54a to the short circuit current I54b in high solar radiation are significantly different. That is, the ratio between the operating current and the short circuit current is substantially constant in the MPPT control, but is largely changed in the output suppression control. Focusing on this point, the ratio J of the operating current and the short circuit current is introduced as a variable for estimating the operating point of the solar battery cell.

The IV characteristic of a photovoltaic cell is shown to FIG. 4A, and the electric power-voltage characteristic (PV characteristic) of a photovoltaic cell is shown to FIG. 4B. The photovoltaic cell is assumed to be operating at an operating point 400, and the slope of the IV characteristic (∂I / ∂V) 401 and the slope of the PV characteristic (∂P / ∂V) 402 at that time are combined. Is shown. Further, as shown in FIG. 4A, the operating current of the solar cell at the operating point 400 is I _opa , and the operating voltage is V _opa . Further, the operating current when the operating voltage of the solar battery cell is zero is referred to as a short circuit current I _sca, and the operating voltage when the operating current of the solar battery cell is zero is referred to as the open circuit voltage V _oca . Also, _let J be the ratio of the short circuit current I _sca of the solar battery cell to the operating current I _opa .

  The equivalent circuit of the photovoltaic cell 11 is shown in FIG. The solar battery module 1 a can be represented as a plurality of solar battery cells 11 arranged in series and divided into bypass diodes 12. It is the solar cell string 1b that the solar cell modules 1a are further connected in series. The solar battery cell 11 can be represented as an equivalent circuit in which a series resistor 16 is connected in series to the current source 13, the pn junction diode 14, and the shunt resistor 15 connected in parallel. A current proportional to the amount of solar radiation is supplied from the current source 13. In addition, when any of the solar cells 11 in the solar cell module 1 a fails, the current path bypasses the bypass diode 12.

As shown in FIG. 1, the DC current and DC voltage of the solar cell string group 1 are measured in units of power conditioners. Therefore, _assuming that the DC current I _op and DC voltage V _{op of} the solar cell string group measured by the power conditioner 3, the operating current per solar cell at this time is I _opa (= I _op / N _str Note that N _str is the number of solar cell strings 1 b bundled in the power conditioner 3 (referred to as “the number of strings”), and the operating voltage is V _opa (= V _op / N _cell : N _cell is a solar cell The number of solar cells 11 connected in series in the string 1 b (referred to as “the number of cells”).

Here, the magnitude of the reverse saturation current I _s of the solar battery cell is expressed by (Equation 1).

Here, A is a saturation constant, -E _go is a band gap [eV] of silicon (material of solar battery cell), q is a load amount, n _f is a junction coefficient (diode performance index), k is a Boltzmann coefficient, T _a is the operating temperature [K] of the solar cell. By transforming (Equation 1), (Equation 2) is obtained.

Further, _assuming that the amount of current I ₁ flowing to the current source 13 and the amount I _{2 of} current flowing to the pn junction diode 14, the relationship of I _opa = I ₁ −I ₂ is established, specifically, .

In _equation (3), I _sca is converted to a function of I _opa using the definition of J (J = I _opa / I _sca ). By transforming (Equation 3), (Equation 4) is obtained.

By taking the difference between the left side and the right side of (Equation 2) and (Equation 4) respectively, I _s (Eq. 5), which is a relational expression from which I _s is eliminated, is obtained, and this is transformed to The equation (6) for calculating the operating temperature T _a is obtained.

Thus, it becomes possible to calculate the operating temperature of the solar cell from the measured operating voltage V _opa of the solar cell and the operating current I _opa .

On the other hand, (Expression 7) is obtained by substituting (Expression 1) into I _s of ( _Expression 3).

  From (Equation 7), ∂I / ∂V is obtained by (Equation 8).

Further, since P = I _opa · V _opa , _∂ P / _∂ V can be obtained by ( _Equation 9).

Thus, the inclination ∂I / ∂V of the I-V characteristic of the solar cell and the inclination ∂P / ∂V of the P-V characteristic of the solar cell are respectively given by (Equation 8) and (Equation 9) uniquely determined once the operating temperature T _a of the solar cell as. Further, the operating temperature T _a can be expressed as a function of the ratio J between the short-circuit current I _sca of the solar cell and the operating current I _opa as shown in ( _Equation 6). In this embodiment, a ratio J matching the ∂I / ∂V and ∂P / ∂V at the operating point from the operating current I _opa calculated from the output of the power conditioner and the operating voltage V _opa , ie, the solar cell Can be determined at which operating point of the IV characteristics. If the ratio J is obtained, it is possible to calculate the operating temperature T _a by equation (6).

  A solar cell diagnostic system is realized using the above relationship. FIG. 12 shows an example of the hardware configuration of the application server 42 (solar cell diagnostic device) that implements the solar cell diagnostic system. The server 42 includes a processor 421, a main storage 422, an auxiliary storage 423, an input / output interface 424, a display interface 425, and a network interface 426, which are coupled by a bus 427. The input / output interface 424 is connected to an input device 429 such as a keyboard or a mouse, and the display interface 425 is connected to the display 428 to realize a GUI. The network interface 426 is an interface for connecting to the network 8. The auxiliary storage 423 is usually composed of a nonvolatile memory such as an HDD or a flash memory, and stores a program executed by the server 42 and data to be processed by the program. The main memory 422 is constituted by a RAM, and temporarily stores a program, data necessary for executing the program, and the like according to an instruction of the processor 421. The processor 421 executes the program loaded from the auxiliary storage 423 to the main storage 422.

  The auxiliary storage 423 stores measured data 4231 acquired from the data server 41, specifications of a solar battery cell 4232 required for diagnosis, other data, a solar cell diagnostic program 4233, and other programs. The solar cell diagnostic program 4233 includes an operating point detection unit 4233a, a failure detection unit 4233b, and a potential power calculation unit 4233c as its main parts. The operating point detector 4233a detects the operating point of the solar battery cell by obtaining the ratio J, and the details will be described with reference to FIGS. The failure detection unit 4233b detects a failure of the solar battery cell from the information of the operating point obtained by the operating point detection unit 4233a, and the details will be described with reference to FIG. Potential power calculation unit 4233c calculates the amount of power generation assumed when performing MPPT control based on the operating conditions of solar cell string group 1 obtained by operating point detection unit 4233a and failure detection unit 4233b, and Potential power is calculated by comparison.

FIG. 6 shows a first flowchart for obtaining the ratio J. The calculation of the ratio J corresponds to the main processing of the operating point detection unit 4233a. The application server 42 stores in advance in the auxiliary storage 423 a reference table 601 for storing values of ∂I / ∂V and values of ∂P / ∂V corresponding to the ratio J. Here, I-V characteristics of a solar cell is considered to vary depending on the operating temperature T _a of the solar cell, the operating temperature T _a is provided a reference table 601a~c for each predetermined range.

As shown in FIG. 1, the direct current (PCS current) I _op and the direct current voltage (PCS voltage) V _op measured by the power conditioner 3 are temporarily stored in the data server 41, and the application server 42 is the data server 41. These data are taken out from and stored in the auxiliary storage (step S60). In order to determine J, an initial value (for example, 0.985) is set (step S61). From the PCS current I _op and the PCS voltage V _op , an operating current I _opa per photovoltaic cell and an operating voltage V _opa are determined (step S 62). The operating temperature T _a , ∂I / ∂V, ∂P / ∂V are calculated when J is a predetermined set value in accordance with the equations (6), (8), and (9) described above Steps S63 to S65). The combination (T _a , ∂ I / ∂ V, ∂ P / ∂ V, J) obtained in this way (step S 66) is compared with the reference table 601, and it is determined whether there is a matching combination in the reference table 601 Are compared (step S67). Note that "coincidence" in this case does not require that the numerical values be exactly the same, and the difference between the values of ∂I / ∂V and ∂P / ∂V in the reference table 601 is not more than a predetermined value. If it is, it may be determined that they match. If there is a matching combination in the reference table 601, the ratio J is determined (step S68). If not, the setting value of the ratio J is changed, and the operating temperature T _a and ∂I / ∂V are again set. , ∂P / ∂V are calculated (step S69).

In the example of FIG. 6, since the reference table 601 is provided for each operating temperature T _a, there is a tendency that the storage capacity of the reference table 601 is increased. In the flowchart of FIG. 7, the reference table to be stored in advance is a reference table at 1.0 kW / m ² of solar radiation and normal temperature (298 K), and the operating current per photovoltaic cell obtained from the PCS current I _op and PCS voltage V _{op opa} , the operating voltage V _opa is once converted into the operating current and the operating voltage at normal temperature, and ∂I / ∂V and ∂P / ∂V obtained from the values are compared with the reference table at normal temperature.

A second flowchart for obtaining the ratio J shown in FIG. 7 will be described. Similar to the flowchart of FIG. 6, the data of the PCS current I _op and the PCS voltage V _op are taken out from the data server 41 (step S70), and an initial value of J (eg 0.985) is set (step S71). The operating current I _opa per solar battery cell and the operating voltage V _opa are determined from the _op and PCS voltage V _op (step S 72), and the operating temperature T when J is a predetermined set value according to ( _Expression 6) calculating the _a (step S73).

Here, the specification of the solar cell module is generally defined as a value at 1.0 kW / m ^{2 of} solar radiation and normal temperature (298 K), so the measured value is converted to a value under this condition. First calculates the assumed solar radiation amount p _a (step S74). Current _{I 1} flowing through the current source 13 shown in FIG. 5 is proportional to the solar _radiation, with the relationship _{I 1 = I sca = p a} · I sc0. In addition, I _sc0 is a short circuit current in the case of solar radiation 1.0 kW / m ² . Here, the definition of the ratio J, because it is I _sca = I _opa / J, holds _{I opa / J = p a ·} I sc0. Therefore, it is possible to calculate the _{p a = (I opa / J} ) / assumed solar radiation p _a the relationship of I _sc0.

Then the measured value (operating current in solar radiation p _a I _opa, operating voltage V _opa) converting solar radiation 1.0 kW / ^{m 2} operating current at I _op0, the operating voltage V _op0 (step S75). Since the ratio J is the ratio of the short circuit current of the solar battery cell to the operating current, I _op0 = I _sc0 · J is satisfied. Further, V _op0 can be expressed by ( _Equation 10) as in ( _Equation 4).

By taking the difference between the left side and the right side of (Equation 4) and (Equation 10), (Equation 11), which is a relational expression in which I _s is eliminated, is obtained. Based on ( _Equation 11), V _op0 can be determined.

Further, the operating current I _op0 and the operating voltage V _op0 are _converted into the operating current I ′ _op0 and the operating voltage V ′ _op0 at normal temperature (298 K) (step S76). As a specification of the solar cell module, generally operating current, the temperature dependency of the operating voltage is defined, the operating temperature T _a and the operating current of the calculated solar cells, based on the temperature dependency of the operating voltage, operating current I ' _op0 ' can be converted to the operating voltage _V'op0 . Alternatively, the operating voltage V ' _op0 can also be determined based on the temperature characteristics of the operating voltage of the solar battery cell. The temperature characteristic of the operating voltage of a photovoltaic cell is shown in FIG. The vertical axis represents a direct current voltage (V) per solar cell, and the horizontal axis represents a temperature (T) of the solar cell. The temperature characteristic 800 of the operating voltage is known to exhibit a linear characteristic. In the case of silicon solar cells, ∂V / 約 T is about -2mV / K. From the relationship shown in FIG. 8, the relationship of equation 12 is derived.

The more accurate value of _V'op0 can be determined using the relationship of ( _Equation 12).

Thus, the values of the operating current I ' _op0 and the operating voltage V' _op0 converted to the solar radiation 1.0 kW / m ² and the normal temperature 298 K can be obtained from the measured values. In accordance with the equations (8) and (9) described above, JI / ∂V and ∂P / ∂V are calculated when J is a predetermined set value (steps S77 to S78). The combination (∂I / ∂V, ∂P / ∂V, J) obtained in this way (step S79) is compared with the reference table 701, and whether there is a matching combination in the reference table 701 is compared. (Step S80). Note that “coincidence” in this case also does not require that the numerical values be exactly the same, and the difference with the values of ∂I / ∂V, ∂P / ∂V in the reference table 701 is less than or equal to a predetermined value, respectively. It may be determined that there is a match in a certain case. If there is a matching combination in the reference table 701, the ratio J is determined (step S81). If not, the setting value of the ratio J is changed, and ∂I / ∂V, ∂P / ∂ again. V is calculated (step S82).

FIG. 9 is a flow of failure diagnosis of the solar cell module, and shows the process executed by the failure detection unit 4233b. Operating temperature T _a and J obtained in the flow of FIG. 6 or FIG. 7, with the solar radiation amount p _a, calculates the operating voltage and current at maximum power point (operating point during MPPT control), for the power of the voltage Check if change ∂P / ∂V = 0. As shown in FIG. 3A, _Jmpp at the maximum power point is constant regardless of solar radiation, and is defined in the specification of the solar cell module. For example, it is _assumed that the value is _Jmpp = 0.93 (step S90). 6 or parameters obtained in FIG. 7 (operating temperature T _a, J, p _a solar radiation amount) was used to calculate the reverse saturation current I _s (step S91), and the operating current I _mpp at the maximum power point V _mpp is calculated (step S92). According to the equations (8) and (9) described above, ∂I / ∂V and ∂P / ∂V at the maximum power point are calculated (steps S93 to S94).

Here, if the result obtained in FIG. 6 or FIG. 7 is correct, ∂P / ∂V = 0 should be established at the maximum power point, and this is confirmed (step S95). If ∂P / ∂V = 0, the number of cells N _cell has an error, that is, it is assumed that the solar cell module includes a broken solar cell, and the number of cells N _cell is reset (step S96) Return to the point ** in FIG. 6 or FIG. 7 and start over from the calculation of J. When ∂P / ∂V = 0, the diagnosis flow of the present embodiment converges, and the number of failures in the solar cell can be determined from the cell number N _{cell at} this time (step S97).

  FIG. 10 is a GUI (Graphical User Interface) for displaying the diagnosis result according to the present embodiment by the Web server. The diagnosis result is displayed on the display screen of the Web server or the display screen of the PC terminal 9a or the portable terminal 9b. The diagnosis result is displayed in PCS units, and items such as PCS ID 100, latest diagnosis date and time 101, ideal current 102, measured current 103, failure loss 104, assumed solar radiation amount 105, and assumed temperature 106 are displayed. Since the estimated solar radiation amount 105 and the estimated temperature 106 are calculated in the diagnosis flow of this embodiment, for example, the amount of current when operating at the maximum power point as the ideal current 102 is calculated from these, and the power conditioner is actually It may be made to be able to compare with the measurement current 103 measured by the current measurement device 3. Further, since the number of failures of solar cells can be determined by the flow of FIG. 9, for example, the ratio of the number of failure solar cells to the number of solar cells connected to one power conditioner 3 is displayed as failure loss 104 It is also good. If there is a failure loss, it is desirable to display in an easily visible form such as changing the background color as in line 107. Alternatively, the amount of solar radiation 108 measured by a pyranometer installed at the site may be displayed.

  Further, in the output suppression control time zone, the potential power amount may be displayed as shown in FIG. For example, items such as PCS · ID 110, output control value 111, output suppression value 112, total capacity 113, PV output 114, potential electric energy (ΔP) 115 are displayed. The output control value 111 is an output value instructed to each power conditioner, and the output suppression value 112 corresponds to the output value of the entire site, that is, the sum of the output control values 111. The total capacity 113 displays the power generation capacity originally owned by the site. The PV output 114 is an actual power value output from each power conditioner. The potential power calculation unit 4233c calculates how much power value can be obtained by operating at the maximum power point, and calculating and displaying each potential power amount by taking the difference from the actual output value 114. It will be possible.

1: Solar cell string group, 1a: Solar cell module, 1b: Solar cell string, 2: Connection box, 21: Backflow prevention diode, 22: Fuse, 23: Circuit breaker, 3: Power conditioner, 31: Current measurement device , 32: voltage measuring device, 33: sampling processing unit, 34: control waveform generation unit, 35: control unit, 36: DC / AC conversion unit, 37: signal conversion transmission device, 4: data center, 41: data server, 42: Application server, 43: Web server, 44: Relay device, 45: Physical switch, 46: Firewall, 5: HUB, 6: PLC, 7: Transmission device, 8: Network, 9a: PC terminal, 9b: Mobile terminal .

Claims (15)

A solar cell diagnostic device for diagnosing a solar cell having a solar cell module in which a plurality of solar cells are connected in series, comprising:
A processor,
With memory
A reference table for storing combinations of the ratio of the short circuit current to the operating current, the slope of the current-voltage characteristic and the slope of the power-voltage characteristic at a plurality of operating points of the solar cell, and read into the memory by the processor And auxiliary memory for storing a solar cell diagnostic program to be executed;
The solar cell diagnostic program has an operating point detection unit,
The operating point detection unit calculates a current based on the set ratio of the short circuit current to the operating current of the solar battery cell, the set ratio and the measured operating current and the operating voltage of the solar battery cell. The solar cell diagnostic device which calculates | requires the operating point of the said photovoltaic cell based on agreement with the inclination of voltage characteristics, and the combination of inclination of electric power-voltage characteristics, and either of the combinations in the some operating point memorize | stored in the said reference table. In claim 1,
The operating point detection unit calculates the operating temperature of the solar cell based on the set ratio, and the solar cell based on the operating temperature and the measured operating current and operating voltage of the solar cell. The solar cell diagnostic device which calculates the inclination of the current-voltage characteristic of, and the inclination of a power-voltage characteristic. In claim 1,
The reference table has a plurality of tables according to the operating temperature of the solar battery cell, and for each of the plurality of tables, a ratio of a short circuit current to an operating current at a plurality of operating points of the solar battery cell, a current -A solar cell diagnostic device that stores combinations of slopes of voltage characteristics and slopes of power-voltage characteristics. In claim 1,
The reference table is a ratio of a short circuit current to an operating current at a plurality of operating points of the solar battery cell, a slope of current-voltage characteristics, and a slope of power-voltage characteristics at a predetermined amount of solar radiation and a predetermined operating temperature. Solar cell diagnostic device that stores combinations. In claim 4,
The operating point detection unit calculates the operating temperature and the estimated solar radiation amount of the solar battery cell based on the set ratio, and the calculated operating temperature of the solar battery cell and the estimated solar radiation amount of the solar battery cell A solar cell diagnostic device for calculating a slope of current-voltage characteristics and a slope of power-voltage characteristics of the solar battery cell at the predetermined amount of solar radiation and the predetermined operating temperature based on the measured operating current and the operating voltage . In claim 1,
The solar cell diagnostic program has a failure detection unit,
The solar cell module according to claim 1, wherein the failure detection unit determines whether the solar battery module includes a broken solar battery cell based on whether a slope of a power-voltage characteristic at a maximum power point of the solar battery cell is zero. Battery diagnostic device. In claim 6,
The failure detection unit determines the maximum power point of the solar battery cell according to the ratio of the short circuit current to the operating current at the operating point of the solar battery cell determined by the operating point detection unit and the operating temperature of the solar battery cell. Calculating an operating current and an operating voltage at the maximum power point, and calculating a slope of a power-voltage characteristic at the maximum power point of the solar battery cell based on the operating current and the operating voltage at the calculated maximum power point;
When the calculated inclination of the power-voltage characteristic is not 0, the solar cell module is assumed to include a broken solar cell, and the operating point detector recalculates the operating point of the solar cell. Diagnostic device. In claim 6,
The solar cell diagnostic program has a potential power calculation unit,
The said latent electric power calculation part calculates the amount of power generation assumed when the photovoltaic cell contained in the said solar cell implements MPPT control, The solar cell diagnostic apparatus which calculates potential electric power by comparing with an actual value. A solar cell string in which solar cell modules in which a plurality of solar cells are connected in series are connected in series;
A solar cell string group having a plurality of the solar cell strings connected in parallel;
A power conditioner to which the solar cell string group is connected;
And the solar cell diagnostic device according to any one of claims 1 to 8.
The power conditioner includes a current measurement device that measures a direct current output from the solar cell string group, and a voltage measurement device that measures a DC voltage output from the solar cell string group.
The said solar cell diagnostic apparatus is a solar power generation system which calculates the operating current and operating voltage of the said photovoltaic cell based on the direct current value and DC voltage value which were measured by the said power conditioner. In claim 9,
The power conditioner includes a control unit that performs MPPT control or output suppression control, and a DC / AC conversion unit.
The control unit steps up or down the output from the solar cell string group,
The said DC-AC conversion part converts the output from the said photovoltaic cell string group pressure | voltage-risen or pressure-reduced by the said control part into alternating current. A solar cell diagnostic method for diagnosing a solar cell having a solar cell module in which a plurality of solar cells are connected in series, comprising:
Storing in advance a reference table storing combinations of the ratio of the short circuit current to the operating current at the plurality of operating points of the solar battery cell, the slope of the current-voltage characteristic and the slope of the power-voltage characteristic;
Set the ratio of the short circuit current of the solar battery cell to the operating current,
A combination of the slope of the current-voltage characteristic and the slope of the power-voltage characteristic calculated based on the set ratio and the measured operating current and operating voltage of the solar battery cell, and a plurality of stored in the reference table The solar cell diagnostic method which calculates | requires the operating point of the said photovoltaic cell based on agreement with either of the combinations in an operating point. In claim 11,
The operating temperature of the solar cell is calculated based on the set ratio, and the slope of the current-voltage characteristic of the solar cell based on the operating temperature and the measured operating current and operating voltage of the solar cell, A solar cell diagnostic method for calculating a slope of power-voltage characteristics. In claim 11,
The solar cell diagnostic method which determines whether the solar cell module contains the malfunctioning photovoltaic cell based on whether the inclination of the electric power-voltage characteristic in the maximum electric power point of the said photovoltaic cell becomes zero. In claim 13,
The operating current and operating voltage at the maximum power point of the solar cell are calculated from the ratio of the short circuit current to the operating current at the operating point of the solar cell and the operating temperature of the solar cell, and the calculated maximum Based on the operating current and the operating voltage at the power point, the slope of the power-voltage characteristic at the maximum power point of the solar battery cell is calculated;
The solar cell diagnostic method which recalculates the operating point of the solar cell as the solar cell module includes a broken solar cell if the inclination of the calculated power-voltage characteristic is not zero. In claim 13,
The solar cell diagnostic method which calculates potential electric power by calculating the electric power generation amount assumed when the photovoltaic cell contained in the said solar cell implements MPPT control, and comparing with an actual value.

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