JP2018182994A - Diagnostic system and method for photovoltaic strings - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a diagnosis system for solar cell strings that without pasting temperature sensors on solar cell strings, diagnosis targets, is capable of performing performance diagnosis on the solar cell strings.SOLUTION: A measurement reference panel is installed under an insolation condition equivalent to that of a surface on which solar cell strings are installed. The measurement reference panel has a conversion characteristic and temperature characteristic equivalent to those of the solar cell strings. According to an instruction by a diagnosis device, I-V characteristics of the solar cell strings and measurement reference panel are measured simultaneously. On the basis of the I-V characteristics of the solar cell strings and measurement reference panel, a maximum output power value Pms of the solar cell strings and the maximum output power value Pmk of the measurement reference panel are calculated. On the basis of the maximum output power value Pms of the solar cell strings and the maximum output power value Pmk of the measurement reference panel, a rated output ratio Pms/Pmk is calculated. On the basis of the calculated rated output ratio Pms/Pmk, performance diagnosis on the solar cell strings is performed.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a diagnostic system and diagnostic method for performing performance diagnosis of solar cell strings performing solar power generation.

  In a solar power generation system, a plurality of solar cell modules installed on a plurality of solar radiation surfaces are connected in series to constitute a solar cell string, and a plurality of solar cell strings are further connected in parallel to organize a solar cell array An organized solar cell array is connected to the junction box and the power conditioner. The power conditioner is a component that reverses the generated power of the solar cell array as AC power with respect to the system power supply.

  In a solar power generation system, although the output of a solar cell array is designed in the area of input voltage and input current that is advantageous in terms of conversion efficiency of a power conditioner, power generation performance gradually declines with use. The power generation performance of the solar power system is also equivalent to the recovery of the long-term accumulated power generation for investment in the solar power system. Therefore, for solar cell modules that make up a solar cell array, it is common to provide long-term power guarantee such as 80% or more of nominal power ratio in 20 years after installation together with the initial nominal power value of solar cell modules in recent years It has become. Therefore, in the diagnosis of solar cell modules, it is desired not only to perform accurate performance diagnosis but also to reduce the cost of diagnosis associated with the increase in the number of output diagnoses, thus a low-cost performance diagnosis method under installation environment is required. The

Under such technical background, Patent Document 1 below discloses a characterization apparatus capable of performing failure diagnosis of solar cell strings in more detail. Specifically, in the method disclosed in Patent Document 1, the solar cell strings to be diagnosed are subjected to measurement of the amount of solar radiation with a pyranometer and temperature measurement of the solar cell strings with a thermometer. Then, the current-voltage characteristics of the solar cell strings are obtained based on the measurement results, and are further converted to a solar radiation amount of 1 kW / m ² as a reference condition and a module temperature of 25 ° C. Apart from these processes, the memory of the characteristic evaluation device stores a plurality of reference characteristics based on current-voltage characteristics corresponding to individual defects that may occur in the solar cell strings. The current-voltage characteristic converted to the reference state is compared with a plurality of reference characteristics read from the memory, and a reference characteristic approximating the converted current-voltage characteristic is selected from the plurality of reference characteristics and selected. Based on the determined reference characteristics, the failure of the solar cell strings is determined.

  The following Patent Document 2 and Non-Patent Documents 1 and 2 are documents related to performance diagnosis of solar cell strings. The contents of these documents will be appropriately referred to in the description of the embodiment.

Patent No. 5162737 gazette JP, 2015-159190, A

JIS C 8919-1995 Crystalline solar cell module outdoor power measurement method PVTEC (Photovoltaic Technology Research Association) News: March 2016 issue VOL. 72, Special Feature 2 “Improvement of solar cell outdoor measurement”

  In the method of Patent Document 1, it is necessary to measure the temperature of the solar cell strings. For this reason, it is necessary to paste a temperature sensor on the back of the solar cell strings. However, in the case of a solar cell array installed on a roof slope or a large outdoor gantry surface, the solar cell strings may need to be removed, and the temperature sensor could not be easily attached. For this reason, a method for performing performance diagnosis of solar cell strings without attaching a temperature sensor to the solar cell strings to be diagnosed has been desired.

  The present invention has been made in view of the above, and it is an object of the present invention to provide a solar cell strings diagnostic system capable of performing performance diagnosis of solar cell strings without attaching a temperature sensor to the solar cell strings to be diagnosed. With the goal.

  In order to solve the problems described above and to achieve the object, the present invention is a diagnostic system that performs performance diagnosis of solar cell strings that perform solar power generation. This diagnostic system has the conversion characteristics and temperature characteristics equivalent to solar cell strings, and measures the characteristics of the measurement reference panel installed under the solar radiation conditions equivalent to the installation surface of solar cell strings, and solar cell strings Based on the measurement results and calculation results of the first measurement device, the second measurement device that measures the characteristics of the measurement reference panel, and the first measurement device and the second measurement device, the performance diagnosis of the solar cell strings is performed And a diagnostic device. The first measuring device measures the current-voltage characteristics of the solar cell strings according to the measurement instruction from the diagnostic device, and based on the measured current-voltage characteristics, the maximum output power value which is the electric power value at the maximum output point of the solar cell strings. Calculate and send to the diagnostic device. The second measuring device measures the current-voltage characteristic of the measurement reference panel in accordance with the measurement instruction, calculates the maximum output power value of the measurement reference panel based on the measured current-voltage characteristic, and transmits it to the diagnostic device. The diagnostic device calculates a rated output ratio that is a ratio of the maximum output power value of the solar cell strings to the maximum output power value of the measurement reference panel, and performs performance diagnosis of the solar cell strings based on the calculated rated output ratio.

  According to the present invention, it is possible to perform performance diagnosis of solar cell strings without attaching a temperature sensor to the solar cell strings to be diagnosed.

The schematic diagram which shows the structure of the diagnostic system of the solar cell strings which concern on embodiment The circuit diagram which shows the detailed structure of the measuring apparatus in embodiment Block diagram showing the functional configuration of the diagnostic device in the embodiment Flow chart showing the operation of the main part of the diagnostic system according to the embodiment Figure showing an example of measurement results of IV characteristics The figure which shows an example of P curve which put output power value P (measurement I x measurement V value) in a row Diagram showing the relationship of diagnostic string output to measurement reference panel output Diagram showing the relationship between the rated output ratio Pms / Pmk to the measurement reference panel output Diagram showing time fluctuation of maximum output power value Pm in measurement reference panel Diagram showing the relationship of diagnostic strings output to solar radiation Figure showing the relationship between rated power ratio Pms / Pmk to solar radiation Diagram showing measurement example of panel temperature Figure showing a display example of aging of rated output ratio Pms / Pmk Figure showing an example of measurement results at diagnosis Figure showing an example of measurement results when measured using a thermoelectric solar actinometer The figure which shows the fluctuation | variation of the maximum output power value Pm of the solar cell module (measurement reference panel) obtained on the same solar radiation as the measurement result shown by FIG. 15 A block diagram showing an example of a hardware configuration for realizing the function of the diagnostic device in the embodiment

  In the present invention, as a performance diagnosis of a solar cell module, an output guarantee method in units of solar cell strings is disclosed. The method according to the present invention focuses on the fact that the power conditioner used in the photovoltaic power generation system generates power by performing maximum power point tracking control in order to use the power generation output of the solar cell at the maximum output point. It is. Specifically, the power value (hereinafter referred to as “maximum output power value”) Pm at the maximum output point of the solar cell strings is used. The output of the measurement reference panel equivalent to the output time response to solar radiation is used as the solar radiation amount reference as the measurement correspondence under varying solar radiation conditions. Hereinafter, a diagnostic system and a diagnostic method of a solar cell string according to an embodiment of the present invention will be described in detail based on the drawings. The present invention is not limited by the following embodiments.

Embodiment.
FIG. 1 is a schematic view showing the configuration of a solar cell strings diagnostic system (hereinafter simply referred to as “diagnostic system”) according to the embodiment. The diagnosis system 80 according to the embodiment mainly includes the diagnosis device 1, the measurement devices 2a and 2b, and the measurement reference panel 3.

  In FIG. 1, when solar cell strings (hereinafter referred to as “diagnosis strings”) 5a and 5b to be diagnosed are connected to the first measuring device and the measuring device 2a to perform the performance diagnosis of the diagnostic strings 5a and 5b. A configuration is shown in which the measurement reference panel 3 serving as a reference and the photoelectric all solar actinometer 4 having a solar radiation amount monitor function are connected to a measurement device 2b which is a second measurement device. The measuring device 2a is a device for measuring the characteristics of the diagnostic strings 5a and 5b, and FIG. 1 shows a connection at the time of measurement of the diagnostic strings 5a. The measuring device 2 b is a device that measures the characteristics of the measurement reference panel 3. In addition, both functions are the same, and when naming measurement apparatuses 2a and 2b generically, it describes with "the measurement apparatus 2."

  The measuring devices 2a and 2b and the diagnostic device 1 are connected by wireless or wired communication means. The diagnostic device 1 inputs information necessary for measurement, and transmits measurement instructions and setting information to the measurement devices 2a and 2b. The measuring devices 2 a and 2 b having received the measurement instruction and the setting information from the diagnostic device 1 transmit the measurement result and the calculation result to the diagnostic device 1. The diagnostic device 1 displays and records information necessary for performance diagnosis of the diagnostic strings 5a and 5b based on the measurement result and the calculation result, and carries out printing if necessary. The details of the function of the diagnostic device 1 and the details of the communication function between the diagnostic device 1 and the measuring device 2 will be described later.

  Further, in FIG. 1, the diagnostic strings 5 a and 5 b are connected to the power conditioner 7 via a junction box 6 provided with a switch 17 and a backflow prevention diode 18. The system power supply 8 is connected to the power conditioner 7. The measuring device 2a is connected to the input end side of the junction box 6, that is, the side to which the diagnostic strings 5a and 5b are connected. When connecting the diagnostic strings 5a, 5b and the measuring device 2a to the connection box 6, the switch 17 of the connection box 6 is open. That is, the electrical connection of the diagnostic strings 5a, 5b is switched from the power conditioner 7 side to the measuring device 2a side.

  Although FIG. 1 illustrates the diagnostic strings 5a and 5b in which eight solar cell modules are connected in series, the present invention is not limited to this configuration. That is, the series number of solar cell modules is arbitrary. Moreover, although the solar cell array provided with diagnostic strings 5a, 5b of 2 parallel is illustrated in FIG. 1, it is not limited to this structure. That is, the parallel number of diagnostic strings is arbitrary.

  A temperature sensor 15 is attached to the back surface of the measurement reference panel 3. The measurement reference panel 3 is installed on the installation surface of the diagnostic strings 5a, 5b.

The measurement reference panel 3 has a structure equivalent to the solar cell module used in the diagnostic strings 5a and 5b, and is configured using an equivalent solar cell. The measurement reference panel 3 has power values at the same or equivalent maximum power points as the diagnostic strings 5a and 5b, and temperature characteristics, spectral sensitivity characteristics, and heat radiation characteristics equivalent to each other. When such a measurement reference panel 3 is used, the diagnostic strings 5a and 5b and the measurement reference panel 3 have the same cell temperature under the amount of solar radiation and the wind speed which can be regarded as the same or the same. The measurement reference panel 3 has calibration output data under the reference conditions of the solar cell performance measurement by the solar simulator. A typical example of the reference condition is a solar radiation intensity of 1 kW / m ² and a cell temperature of 25 ° C. This reference condition is defined in the above non-patent document 1. If the temperature characteristics and temperature rise of the diagnostic strings 5a and 5b and the measurement reference panel 3 are the same, the temperature sensor 15 attached to the measurement reference panel 3 is not essential for diagnosis, and in FIG. It is described as a usage example for

  The manufacturer of the solar cell module can manufacture the measurement reference panel 3 with the small solar cell module specification, so that the measurement reference panel 3 can be provided at low cost. The manufacturer of the solar cell module may provide an installation jig that simulates the installation environment of the solar cell module for installing the measurement reference panel 3 together with the calibrated performance data. When the installation jig is used, it is not necessary to install the measurement reference panel 3 on the same plane as the installation surface of the diagnostic strings 5a and 5b, that is, the same solar radiation surface. Note that an example of the installation jig is disclosed in the above-mentioned Patent Document 2, so please refer to the contents of the Patent Document 2.

  FIG. 2 is a circuit diagram showing a detailed configuration of the measuring device 2 in the embodiment. In FIG. 2, together with the measuring device 2 b to which the measurement reference panel 3 is connected, the photoelectric climax radiation actinometer 4 connected to the measuring device 2 b and the diagnostic device 1 to which the measurement result and the calculation result of the measuring device 2 b are transmitted And are shown. The diagnostic device 1 performs performance diagnosis of the diagnostic strings 5a and 5b based on the measurement results and calculation results of the measurement devices 2a and 2b.

  As illustrated, the measuring device 2 b is configured by using the charge switch 11, the load capacitor 12, the capacitance switching switch 13, the discharge resistor 14, and the resistors 20 to 23 as circuit elements. The measuring device 2 b further includes a control unit 9. The function of the control unit 9 is divided into a communication block 9a and a control block 9b.

  The load capacitor 12 is a capacitive element used to measure the current-voltage characteristic (hereinafter referred to as “I-V characteristic”) of the measurement reference panel 3. The electrical connection between the measurement reference panel 3 and the load capacitor 12 can be switched by the charge switch 11 and the capacity changeover switch 13. By closing at least one of the charge switch 11 and the two capacity changeover switches 13, a circuit is formed in which at least one of the load capacitors 12 is charged from the measurement reference panel 3. The control block 9 b performs opening and closing of the charge switch 11 and the capacity changeover switch 13.

  The discharge resistor 14 is a discharge resistor for discharging the charge stored in the load capacitor 12. It is not necessary to separate the discharge resistance 14 even during non-measurement and during measurement of the IV characteristic by setting the resistance to a high resistance value so as to reduce the measurement error. Therefore, since the switch for separating is not required, the configuration for connecting the discharge resistor 14 to the circuit becomes simple.

  C1 and C2 are capacitance values of the load capacitor 12. The I-V characteristic sweep time can be changed by switching the capacitance value of the load capacitor 12 inserted in the charge path between C1 and C2. The IV characteristic sweep time is the ON time of the charge switch 11 when measuring the maximum output power value Pm of the measurement reference panel 3, in other words, the connection time of the load capacitor 12 in the charge path.

Examples of I-V characteristic sweep times assumed in the configuration of the present embodiment are 50 msec and 200 msec. Here, in Non-Patent Document 2, when the I-V characteristic sweep time is 100 msec to 200 msec, utilizing the fact that the frequency of solar radiation fluctuation is within ± 0.4% is 90%, the irradiance 300 W / ^{m 2} or more, reporting is the possible performance diagnosis in about sweep time 200 msec. An I-V characteristic sweep time of 200 msec is included in the scope of this report content. With the configuration of the present embodiment, an I-V characteristic sweep time of 200 msec can be selected by selecting a combination of capacitance values of C1 and C2.

  The charging curve at the time of I-V characteristic measurement changes the charging time depending on the output current value of the diagnostic strings and the load capacitor capacity. For this reason, by selecting the capacitor capacity according to the amount of solar radiation, the sweep time can be shortened with respect to the variation of the amount of solar radiation. With the configuration of the present embodiment, an I-V characteristic sweep time of 50 msec can be selected by selecting a combination of capacitance values of C1 and C2.

  In addition, when changing a capacitor capacity according to the amount of solar radiation, it is preferable to make the time constant at the time of each IV characteristic measurement of measurement standard panel 3 and diagnostic strings 5a and 5b correspond. By matching the time constants, it is possible to improve the accuracy of performance diagnosis with respect to solar radiation variation.

  The measuring device 2b measures the IV characteristic by charging the capacitor charging voltage V charged in the load capacitor 12, the charging current I when charging the load capacitor 12, and the radiation of the photoelectric solar eclipse meter 4. Measure the illuminance LX. The capacitor charging voltage V is obtained by applying to the control block 9 b a divided voltage by the resistor 22 of the resistors 21 and 22 connected in series. The charging current I is obtained by applying a voltage generated at one end of the resistor 23 to the control block 9 b. The irradiance LX is obtained by applying a voltage generated at one end of the resistor 20 to the control block 9b. The control block 9 b has a high speed AD converter not shown. The high-speed AD converter performs AD conversion of the capacitor charging voltage V, the charging current I, and the irradiance LX at high speed on the order of several microseconds in one measurement sweep. The control block 9b calculates the IV characteristic and the amount of solar radiation based on the AD converted digital value. The control block 9 b calculates the power from the measurement result of the IV characteristic and extracts the maximum output power value Pm. The calculation result of the control block 9b is transmitted to the diagnostic device 1 through the communication block 9a.

  Next, the function of the diagnostic device 1 will be described. FIG. 3 is a block diagram showing a functional configuration of the diagnostic device 1. The diagnostic device 1 includes a data input unit 33, a storage unit 34, a display unit 35, an arithmetic unit 37, a communication unit 38, and a control unit 39. Each part in the diagnostic device 1 is connected by a bus 40.

  The data input unit 33 uses various devices including a keyboard and a pointing device, and inputs and sets various information to the diagnostic device 1. The storage unit 34 stores the input information input to the diagnostic device 1 and various types of information calculated by the calculation unit 37. The display unit 35 displays various information including a display screen in each process in the diagnostic device 1 and input information from the outside.

  The computing unit 37 performs various computing processes in the diagnostic process in the diagnostic device 1. The communication unit 38 transmits and receives necessary information to and from the measuring device 2 by wireless or wired communication means. The control unit 39 controls the entire units in the diagnostic device 1.

  Next, (1) information input and display of diagnostic strings to be diagnosed, and (2) characteristic measurement of diagnostic strings, with respect to the function of the diagnostic apparatus 1 viewed from the evaluator including the administrator or service person who performs performance diagnosis of diagnostic strings. And (3) divided into three categories of display, recording and printing of diagnostic results.

(1) Information input and display of diagnostic strings to be diagnosed (a) If the diagnostic strings to be diagnosed are of a new system, the following information is registered in the database.
-Identification name of diagnostic system-Placement of diagnostic strings, identification name and series-parallel configuration-Solar cell module type name constituting diagnostic strings-Module rated value (short circuit current, open voltage, maximum output, maximum output operating voltage) according to the database , Obtain the maximum output operating current), calculate and display the rated value of each string ・ Display the measured solar radiation condition and sweep time set for each solar cell type used by the database (b) Diagnostic strings already registered system In the case of the above, the registration data is recalled and the revision such as the panel expansion is implemented.
(C) If the diagnostic strings are of the measurement system for investigation, register information to that effect.

(2) Characteristic measurement of diagnostic strings This function has the following three modes.
(A) Solar radiation determination mode Whether or not the output determination condition is satisfied during the measurement time interval according to the type of solar cell array to be targeted, specifically, the amount of solar radiation and the measurement determined according to the solar cell type In order to determine whether or not the amount of solar radiation fluctuation is satisfied, the illuminance is preliminarily measured and displayed in the measurement time width.
(B) Measurement mode (b-1) Setting mode-Set the target system and diagnostic string name, and display the guarantee rating of the diagnostic string-Set the measuring device number and measuring time-Measuring device number (illuminometer, reference cell, Registration of measurement device) ・ Set measurement time zone so that a wide range of solar radiation condition can be obtained by the solar radiation judgment result. (B-2) Measurement display mode ・ Start and stop of measurement ・ Display change of data during measurement ・ Measured Display of IV characteristics · Solar radiation Pm characteristics display

(3) Display, recording and printing of diagnostic results (a) Display and printing of currently measured data-Using only data that meets the regular judgment conditions, graph the output characteristics of diagnostic strings with respect to solar radiation and rated guaranteed output lines・ Display the ratio of the measured output to the rated output under the standard condition of the solar cell module with the average value and the fluctuation range ・ Reduce the judgment condition by relaxing the judgment accuracy, increase the measured data, and diagnose the solar radiation amount Display the output characteristics of the strings and the rated guaranteed output line as a graph ・ Display the ratio of the measured output to the rated output under the standard condition of the solar cell module as average value and fluctuation range (b) Data storage and reference to past records ・ Diagnostic object Record of system configuration and diagnosis result ・ Refer and update past records of existing system ・ Print of measurement result and data registration of measurement result (c) Past registration Display and printing of data ・ Viewing and printing of past diagnosis results ・ Transition data table of past diagnosis results browsing and printing

When the diagnostic device 1 operates as described above, the communication block 9 a of the measurement device 2 receives the following information from the diagnostic device 1.
(A) Setting data-Load capacitor setting-Voltage range and current range setting (b) Measurement start instruction (c) Data transmission instruction-Device data transmission instruction-Operation status transmission instruction-Measurement data transmission instruction

The communication block 9 a of the measuring device 2 transmits the following information to the diagnostic device 1.
・ Device data ・ Operation status ・ Measurement data

The control block 9b of the measuring device 2 operates as follows.
・ Switch switching control ・ Self-diagnosis control of equipment power etc. ・ Device information and measurement data management ・ I-V characteristic measurement ・ Solar radiation measurement ・ Power calculation and Pm extraction ・ Device loss correction calculation

  Next, the main part operation | movement of the diagnostic system 80 which concerns on embodiment is demonstrated with reference to the drawing of FIGS. 1-4 suitably. FIG. 4 is a flowchart showing the operation of the main part of the diagnostic system 80 according to the embodiment.

  First, in step S101, the measurement reference panel 3 is installed under a solar radiation condition equivalent to the installation surface of the diagnostic strings 5a and 5b to be diagnosed. As described above, the measurement reference panel 3 has conversion characteristics and temperature characteristics equivalent to the diagnostic strings 5a and 5b to be diagnosed. In step S102, the measurement time is set by the diagnostic device 1. In step S103, the IV characteristics of the diagnostic strings 5a and 5b and the measurement reference panel 3 are simultaneously measured according to the instruction of the diagnostic device 1. In the process of step S103, the measurement of the IV characteristic is started according to the measurement instruction from the diagnostic device 1, and the measurement is performed during the measurement time instructed from the diagnostic device 1.

  In step S104, based on the diagnostic strings 5a and 5b calculated in step S103 and the IV characteristics of the measurement reference panel 3, the maximum output power value Pms of the diagnosis strings 5a and 5b and the maximum output power of the measurement reference panel 3 The value Pmk is calculated. In step S105, based on the maximum output power value Pms of the diagnostic strings 5a and 5b calculated in step S104 and the maximum output power value Pmk of the measurement reference panel 3, the ratio of the maximum output power value Pms to the maximum output power value Pmk A certain rated output ratio Pms / Pmk is calculated. In step S106, performance diagnosis of the diagnostic strings 5a and 5b is performed based on the rated output ratio Pms / Pmk calculated in step S105.

  The processes of steps S101 to S106 described above will be supplemented with reference to the drawings of FIGS. 5 to 16 as appropriate. FIG. 5 is a view showing an example of the measurement result of the IV characteristic. FIG. 6 is a view showing an example of a P curve in which output power values P (measurement I × measurement V value) are connected. As shown in FIG. 6, a Pmax point is extracted from the P value at the time of load capacitor entry at the initial stage of measurement, that is, the part excluding the P value of the bounce part near measurement value 1, and the Pms value and Pmk at the time of measurement solar radiation It will be a value. FIG. 7 is a diagram showing the relationship between diagnostic string output and measurement reference panel output. FIG. 8 is a diagram showing the relationship of the rated output ratio Pms / Pmk to the measurement reference panel output. FIG. 9 is a diagram showing time fluctuation of the maximum output power value Pm in the measurement reference panel 3. FIG. 10 is a diagram showing the relationship of diagnostic strings output to the amount of solar radiation. FIG. 11 is a diagram showing the relationship between the rated output ratio Pms / Pmk and the amount of solar radiation. FIG. 12 is a diagram showing an example of measurement of the panel temperature. FIG. 13 is a view showing a display example of aging of the rated output ratio Pms / Pmk. FIG. 14 is a diagram showing an example of measurement results at the time of diagnosis. FIG. 15 is a diagram showing an example of the measurement result when the measurement is performed using a thermoelectric global actinometer. FIG. 16 is a diagram showing the fluctuation of the maximum output power value Pm of the solar cell module (measurement reference panel) obtained under the same solar radiation as the measurement result shown in FIG.

  In step S101, the measurement reference panel 3 is installed under the solar radiation condition equivalent to the installation surface of the diagnostic strings 5a, 5b. Here, the meaning of "equivalent" means that the measurement reference panel 3 is installed on the installation surface of the diagnostic strings 5a, 5b or the level adjustment function, the azimuth adjustment function, and the solar radiation surface as disclosed in Patent Document 2. It means installing on the measurement reference panel holding surface of the measurement stand with angle adjustment function.

  If the measurement reference panel 3 is installed under the equivalent solar radiation condition to the installation surface of the diagnostic strings 5a, 5b, the measurement reference panel 3 reaches the same temperature as the diagnostic strings 5a, 5b. In addition, since the measurement reference panel 3 and the diagnostic strings 5a and 5b are designed such that the spectral sensitivity characteristics and the temperature characteristics and thermal time constants of the conversion output and the like match, the solar radiation illuminance and the ambient temperature The rated power ratio Pms / Pmk in the measurement of the diagnostic strings 5a and 5b and the measurement reference panel 3 is constant even for environmental conditions including the conditions, and the measurement of the solar radiation illuminance, the measurement of the measurement reference panel temperature, or the diagnostic strings 5a , 5b is reduced.

As described above, the measurement reference panel 3 has calibration output data under the reference conditions of the solar cell performance measurement by the solar simulator or the like. Therefore, if the panel temperature which is the temperature of the measurement reference panel 3 is measured by the temperature sensor 15, the reference temperature is obtained by the panel temperature and the temperature characteristic value of the measurement reference panel 3 with respect to the measurement output of the diagnostic strings 5a and 5b. It is also possible to perform correction calculation to the above and also to convert the output value of the measurement reference panel 3 into a solar radiation illuminance value (kW / m ² ) equivalent to the amount of solar radiation.

Further, at the time of performance diagnosis, the outputs of the diagnostic strings 5a and 5b and the output of the measurement reference panel 3 are simultaneously measured in an outdoor environment where the amount of solar radiation fluctuates. FIG. 5 is an example of the measurement result of the IV characteristic. Specifically, it is an I-V charging curve when the load capacitor 12 is connected, and is obtained from measurement data when the solar illuminance is 300 kW / m ² . In FIG. 5, K1 is a waveform of the capacitor charging voltage V, and K2 is a waveform of the charging current I. In step S103, a waveform representing the IV characteristic as shown in FIG. 5 is acquired for both the measurement reference panel 3 and the diagnostic strings 5a and 5b.

  If an IV characteristic as shown in FIG. 5 can be measured, a P curve (measurement I value × measurement V value) as shown in FIG. 6 is calculated from measurement data which is the basis of the IV characteristic. Ru. From the P curve, the Pmax point serving as the maximum output power point can be extracted from the portion excluding the P value at the time of load capacitor entry at the initial stage of measurement, and the Pms value and Pmk value at the time of measurement solar radiation can be obtained.

  It is assumed that measurement of each output of the diagnostic strings 5a, 5b and the measurement reference panel 3 is performed n times (n is an integer of 2 or more) under time-series, ie, fluctuating solar radiation conditions. Also, each measurement is called a measurement point, the maximum output of the diagnostic strings 5a and 5b at the measurement point 1 is "Pms1", the maximum output of the measurement reference panel 3 at the measurement point 1 is "Pmk1", and the diagnostic strings at the measurement point n The maximum output of 5a and 5b is denoted as "Pmsn", and the maximum output of the measurement reference panel 3 at the measurement point n is denoted as "Pmkn".

  If the maximum output power values Pms1 to Pmsn and the maximum output power values Pmk1 to Pmkn are obtained, n rated output ratios Pms1 / Pmk1 to Pmsn / Pmkn are calculated. In the case of the present embodiment, the measurement reference panel 3 having conversion characteristics and temperature characteristics equivalent to the diagnostic strings 5a and 5b is used. For this reason, the rated output ratio does not depend on the changing solar radiation condition, and becomes constant magnification when there is no measurement error. A specific example will be described below.

  Assuming that the nominal maximum output of the measurement reference panel 3 is 230 (W), the nominal maximum output of the diagnostic strings 5a, 5b is 230 (when the diagnostic strings 5a, 5b are configured in series with the same output module 8). It becomes × 8 times W), that is, 230 (W) × 8 = 1840 (W). In the case of this example, the rated output ratio = 8 is a reference line of the output rating. In FIG. 7, a curve K3 is obtained by plotting the measured values when the measurement reference panel output which is the maximum output of the measurement reference panel 3 is taken along the horizontal axis and the diagnostic strings output which is the maximum output of the diagnostic strings 5a, 5b is taken along the vertical axis. And a straight line K4 representing a linear regression equation of the measured values. The linear regression equation representing the straight line K4 is represented by "y = 8.0201x + 2E-05", where x is the horizontal axis and y is the vertical axis. The slope of the linear regression equation "8.0201" represents the rated output ratio. In the example of FIG. 7, it can be understood that the maximum output power value Pm substantially matches the theoretical value “8”, and no deterioration in performance is observed.

  The linear regression equation of the rated output ratio is calculated based on a plurality of measurement results obtained from the maximum output power value Pmk of the measurement reference panel 3 and the maximum output power value Pms of the solar cell strings 5a and 5b. can do. In FIG. 7, since the horizontal axis is the maximum output power value Pmk of the measurement reference panel 3, the difference between the plot distribution of the maximum output power value Pmk and the linear regression line is easy to visually judge as a measurement error . Alternatively, the standard deviation value of the difference from the linear regression equation at each measurement point may be determined, and the determined standard deviation value may be analyzed by output band or the like to diagnose the determination accuracy numerically. By providing such a function, it is possible to quantitatively evaluate the determination accuracy.

  Further, by using the rated output ratios Pms1 / Pmk1 to Pmsn / Pmkn obtained by the measurement, it is possible to express the degree of deterioration with respect to the rated output. In the above example, if the output of the diagnostic strings 5a, 5b is degraded by 10%, the nominal output of the diagnostic strings 5a, 5b under the reference conditions is 230 × 0.9 × 8 = 1,656 (W) is there. At this time, the rated output ratio with respect to the measurement reference panel 3 is 1656/230 = 7.2, and the deterioration degree with respect to the rated output is calculated as 7.2 times / 8 times = 0.9 (90%). As described above, since the degree of deterioration with respect to the rated output can be clearly represented numerically, the evaluator's understanding is facilitated. In addition, if an error variation between the linear regression equation obtained from the data of the rated output ratio and each measurement point is used as a determination index of the measurement error, quantitative judgment to the rated output ratio becomes easy.

  In addition, when diagnosing diagnostic strings 5a, 5b, it may be preferable to operate the diagnostic apparatus 1 and to implement a several times IV measurement time slot | zone. The output ratio is confirmed from the diagnosis graphs of FIGS. 7 and 8 using the graph display function of the diagnostic device 1. When the measurement variation is large, the amount of change in solar radiation is confirmed, and the presence or absence of a shadow effect on the surface of the solar cell module is confirmed. The diagnostic device 1 has a function of displaying time fluctuation of the maximum output power value Pm in the measurement reference panel 3 as shown in FIG. The time variation of the maximum output power value Pm represents the time variation of the amount of solar radiation. Therefore, when the time change of the amount of solar radiation is severe, it is preferable to change the diagnosis time zone to make a diagnosis so as to ensure the necessary diagnostic accuracy.

  FIG. 8 is a graph in which the vertical axis of FIG. 7 is changed to the rated output ratio. According to the example of FIG. 8, even if the output of the measurement reference panel 3 changes with the amount of solar radiation, it is shown that the rated output ratio is constant at 90%. That is, even under conditions in which the weather is cloudy and the amount of solar radiation has changed, a suitable load capacitor corresponding to the amount of solar radiation is selected, and if power measurement can be performed for a short time, linearity maintenance can be expected. The use of the display function shown in FIG. 8 has the effect of facilitating performance diagnosis in an outdoor environment where the variation of the amount of solar radiation is large.

  Note that the maximum output power value Pmk of the measured reference panel 3 is determined to determine the magnitude of the power measurement error or noise amount, and the minimum output level tolerance determination level is set, or the rated output ratio fluctuates. By adopting a method of filtering data in a large time zone, it is also possible to obtain an effect that it is easy to determine the output deterioration due to the measurement area limitation.

  Moreover, although the horizontal axis in FIGS. 7 and 8 uses the maximum output power value Pm obtained from the measurement of the measurement reference panel 3, as shown in FIG. 10 and FIG. It may be changed to To change the maximum output power value Pm of the measurement reference panel 3 to the amount of solar radiation, the temperature characteristics of the maximum output power value Pm of the measurement reference panel 3 and the measurement data of the panel temperature measured by the temperature sensor 15 may be used . FIG. 12 shows an example of measuring the panel temperature. The amount of solar radiation can be determined by converting it to an output value at a reference temperature of 25 ° C. based on the temperature characteristic of the maximum output power value Pm and the measurement data of the panel temperature. Moreover, it is also easy to use for verification of whether there is a problem in the measuring apparatus 2b by comparing the conversion solar radiation value and the illuminance measurement value of the sunshine meter 4.

  In FIG. 10, K5 is a curve plotting the diagnostic string output, K6 is a curve representing the guarantee rate of the diagnostic strings, and an example of the guarantee rate of 80% is shown.

The guarantee power Psg of diagnostic strings is generally determined at a guarantee rate according to the set number of years at a solar illuminance of 1 kW / m ² and a cell temperature of 25 ° C., which is a typical example of standard conditions of solar cell performance measurement. is there. The strings guaranteed power value Psgn with respect to the measurement output Pkn of the measurement reference panel 3 can be calculated using the following equation.

  Psgn = Pkn × (Ps × N / Pk) × G (1)

The meanings of the symbols and formulas shown in the above equation (1) are as follows.
N: Number of serial modules of diagnostic strings Ps: Maximum nominal power of solar cell module (W / piece)
Pk: Measurement standard panel nominal maximum output (W / piece)
G: Output power guarantee ratio at set aging Ps × N / Pk: Nominal power ratio

  Further, in FIG. 8, the horizontal axis is the measurement output Pkn of the measurement reference panel 3 and the vertical axis is the rated output ratio, so a line representing the 80% guarantee rate is a straight line parallel to the horizontal axis. For this reason, using the graph of FIG. 8 makes it possible to perform quantitative evaluation easily and quickly.

  The amount of data can be reduced by storing the diagnostic result by the diagnostic device 1 as a Pm point data group for the amount of solar radiation without storing long-term I-V measurement data. The Pm point data group is a collection of a plurality of maximum output power values Pm obtained from the measurement. The Pm point data group for the amount of solar radiation is preferably stored together with system information such as the identification name of the diagnostic system, the system installation location, and the measurement date and time. In addition to these, it is more preferable to simultaneously store system environment information such as an ambient environment photograph that affects the shadow along with the transition of output performance over several decades. Further, by holding the data of the average value of the rated output ratio and displaying as shown in FIG. 13, it is possible to visibly clearly indicate the aged deterioration rate with respect to the rating of the diagnostic strings 5a, 5b. Furthermore, by providing the display function and printing function of the registration table in which the measurement results at the time of diagnosis as shown in FIG. 14 are provided, the application to the maintenance plan of the solar cell array becomes easy.

  In addition, in order to verify whether the solar radiation fluctuation | variation generate | occur | produced largely during measurement, it is preferable to use the photoelectric whole solar actinometer illustrated also in this Embodiment. The photoelectric whole solar actinometer is faster in time response than the output responses of the diagnostic strings 5a and 5b. By monitoring the amount of solar radiation using a photoelectric whole solar irradiator, the amount of solar radiation at the measurement time point in the IV characteristics of the measurement reference panel 3 and the diagnostic strings 5a, 5b, and the variation of the amount of solar radiation Confirmation is possible. Although photoelectric solar actinometers are effective for monitoring solar radiation, they have thermal time constant differences with solar cell modules, and when the solar spectrum changes seasonally or temporally, various solar cell modules are unique. The difference between the spectral sensitivity and the spectral sensitivity is an error factor. This is also the reason why the measurement reference panel 3 is used as a measurement reference in the judgment of the output performance under the variable solar radiation of the solar cell module.

  FIG. 15: is an example of the measurement result at the time of measuring using a solar ephemeris of a thermoelectric type whose time responsiveness is 15 seconds. Further, FIG. 16 is a waveform in which the value of the maximum output power value Pm obtained under the same solar radiation as the measurement result shown in FIG. 15 is plotted. The time response of the measurement reference panel 3 used in the measurement of FIG. 16 is 1 msec, and the I-V characteristic sweep time is 50 msec.

  According to the measurement results in FIG. 15 and FIG. 16, it is determined that the global ephemeris with low time response is not suitable for measuring the amount of solar radiation, and a thermoelectric global ephemeris is used as a substitute for the measurement reference panel 3 It can be understood that it is inappropriate to

  Also, the influence of the sudden solar radiation fluctuation or the panel temperature fluctuation due to the wind is that the measurement plot points are not arranged on a straight line. For this reason, a data filtering method such as performing averaging data processing on the measurement results, setting the minimum power value as the measurement suitability for the measured power value, or setting the power change rate limit between measurements It is preferable to add the judgment by.

  The present invention is not limited to the example of the embodiment described above. In the present embodiment, the case of carrying out by the inexpensive capacitor load method was illustrated in the measurement of the IV characteristic, but an electronic load method, an XY recorder method, and a bias power supply method can be adopted. In addition, even when the diagnostic strings 5a and 5b are installed in a wide area, installing a plurality of measurement reference panels facilitates the construction of a diagnostic system with a small error.

  Finally, a hardware configuration for realizing the function of the diagnostic device 1 in the embodiment will be described with reference to the drawing of FIG. FIG. 17 is a block diagram showing an example of a hardware configuration that implements the function of the diagnostic device 1 according to the embodiment.

  The processing executed in the diagnostic device 1 in the above-described embodiment can be realized by executing the diagnostic program storing the processing procedure in the diagnostic device 1 by the computer device 100 shown in FIG. The computer apparatus 100 is suitably an integrated personal computer having a communication function, a display function, and a recording function that can be operated outdoors, such as a tablet computer. In addition, the computer device 100 has a diagnostic program in which the processing procedure of the diagnostic device 1 is described, and an operation screen, a registration screen, a communication control screen, and a measurement for establishing cooperation with the measuring device, the printer and the cloud server. A support program that enables display of results and graphs can be installed.

  As shown in FIG. 17, the computer device 100 is represented by a display device 101 represented by an LCD (Liquid Crystal Display), an input device 102 such as a keyboard and a pointing device, a CPU 103 for performing computations, and a ROM (Read Only Memory). Nonvolatile memory 104, volatile memory 105 represented by RAM (Random Access Memory), display memory 106 for storing a display screen to be displayed on the display device 101, and removable external memory represented by flash memory. The external memory interface 107, which is an interface, and the communication interface 108 for communicating with the measuring device 2 are connected via the bus 109.

  A program including a diagnostic program and a support program is stored in the non-volatile memory 104. The program is loaded into the volatile memory 105 and executed by the CPU 103. The program is recorded on a recording medium readable by the computer device 100. Examples of recording media are a hard disk, a CD (Compact Disk) -ROM, a MO (Magneto-Optical disk), and a DVD (Digital Versatile Disk or Digital Video Disk). The diagnostic program can also be distributed via a network such as the Internet. In this case, the program is stored on the non-volatile memory 104 from the information processing terminal connected via the communication interface 108.

  As described above, according to the diagnostic system according to the present embodiment, the installation condition equivalent to the solar cell strings is set for the calibrated measurement reference panel to be compared for each of the solar cell strings constituting the solar cell array. By measuring the maximum output power value Pm value simultaneously and performing output ratio diagnosis based on each Pm value, even if it is placed in the room, the temperature measurement of the solar cell strings is unnecessary, and the efficiency is outdoors It is possible to obtain a diagnostic system capable of comprehensive data recording and analytical judgment.

  Further, in the diagnostic system according to the present embodiment, if the measurement reference panel is configured to be equivalent to the solar cell module configuring the solar cell strings, the solar cell module manufacturer is used for manufacturing assurance along with ease of manufacture. It becomes possible to supply a measurement reference panel with traceability by a solar simulator calibrated according to the spectral sensitivity characteristic of the solar cell module.

  Further, in the diagnostic system according to the present embodiment, the diagnostic device uses a measurement reference panel that matches the solar cell strings to be diagnosed, thereby providing a versatile configuration, various spectral sensitivities, and various temperature characteristics. It is possible to obtain the measurement accuracy confirmation of the manufacturer output guarantee value with high accuracy for the solar cell module type having.

  In addition, it is possible to obtain a plurality of irradiance illuminance points from sunshine conditions in which the measurement diagnosis date is not fine and fluctuates in the diagnostic system according to the present embodiment, and IV characteristic data extending over several tens of megabytes obtained By converting the data into a Pm point data group, it is possible to reduce the amount of data to several tens of kbytes and to make it possible to easily hold long-term periodic inspection data for several decades from the initial characteristics. .

  The configuration described in the above embodiment shows an example of the content of the present invention, and a part of the configuration of the diagnostic system may be incorporated into a junction box or a power conditioner, or another known configuration. It is also possible to combine with the technology, and it is also possible to omit or change part of the configuration without departing from the scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 Diagnostic device, 2, 2a, 2b measuring device, 3 Measurement reference panel, 4 photoelectric whole solar radiation detector, 5a, 5b diagnostic strings, 6 connection box, 7 power conditioner, 9, 39 control part, 9a communication block, 9b control block, 11 charge switch, 12 load capacitor, 13 capacity changeover switch, 14 discharge resistance, 15 temperature sensor, 17 switch, 18 backflow prevention diode, 20, 21, 22, 23 resistance, 33 data input section, 34 memory Unit, 35 display unit, 37 operation unit, 38 communication unit, 40 bus, 80 diagnostic system, 100 computer device, 101 display device, 102 input device, 103 CPU, 104 nonvolatile memory, 105 volatile memory, 106 display memory , 107 external memory interface, 108 communication interface Vinegar, 109 bus.

Claims (14)

A diagnostic system for performing performance diagnosis of solar cell strings performing solar power generation, comprising:
A measurement reference panel having conversion characteristics and temperature characteristics equivalent to the solar cell strings and installed under solar radiation conditions equivalent to the installation surface of the solar cell strings;
A first measuring device for measuring the characteristics of the solar cell strings;
A second measuring device for measuring the characteristics of the measurement reference panel;
A diagnostic device that performs performance diagnosis of the solar cell strings based on measurement results and calculation results of the first measurement device and the second measurement device;
Equipped with
The first measuring device measures the current-voltage characteristics of the solar cell strings according to the measurement instruction from the diagnostic device, and the maximum power value at the maximum output point of the solar cell strings based on the measured current-voltage characteristics Calculating an output power value and sending it to the diagnostic device;
The second measuring device measures the current-voltage characteristic of the measurement reference panel in accordance with the measurement instruction, calculates the maximum output power value of the measurement reference panel based on the measured current-voltage characteristic, and transmits it to the diagnostic device And
The diagnostic device calculates a rated output ratio, which is a ratio of the maximum output power value of the solar cell strings to the maximum output power value of the measurement reference panel, and the solar cell strings are calculated based on the calculated rated output ratio. A diagnostic system of solar cell strings characterized by performing performance diagnosis of the present invention.   The solar apparatus according to claim 1, wherein the diagnostic device uses a plurality of calculated rated output ratios and performs a performance diagnosis on the rated guaranteed output of the solar cell strings with reference to the output of the measurement reference panel. Battery Strings Diagnostic System.   The solar cell according to claim 1 or 2, wherein the time constant when measuring the current-voltage characteristic of the measurement reference panel matches the time constant when measuring the current-voltage characteristic of the solar cell strings. Strings diagnostic system.   The solar cell strings diagnostic system according to any one of claims 1 to 3, wherein the diagnostic device has a function of displaying a plurality of the rated power ratios on a graph together with a nominal power ratio.   The said diagnostic apparatus has a function which displays the graph which plotted the said rated output ratio in each measurement point, The diagnostic system of the solar cell strings in any one of Claim 1 to 3 characterized by the above-mentioned. A temperature sensor is provided to measure the temperature of the measurement reference panel,
The diagnostic device is characterized in that the maximum output power value of the measurement reference panel is converted into the amount of solar radiation at a reference temperature based on the panel temperature detected by the temperature sensor and the temperature characteristic of the measurement reference panel. The diagnostic system of the solar cell strings according to any one of claims 1 to 5.   The solar cell strings diagnostic system according to claim 6, wherein the diagnostic device has a function of graphically displaying the maximum output power value and the rated output ratio of the solar cell strings with respect to the amount of solar radiation. When setting the sweep time when measuring the current-voltage characteristic,
The diagnostic device is a linear regression equation of the rated output ratio based on a plurality of measurement results obtained from the maximum output power value of the measurement reference panel and the maximum output power value of the solar cell strings. The solar cell strings diagnostic system according to any one of claims 1 to 7, wherein the diagnostic system determination accuracy is prepared based on the linear regression equation.   The solar cell strings according to claim 8, wherein the diagnostic device determines a standard deviation value of the difference between the measurement points and the linear regression equation, and diagnoses the determination accuracy from the determined standard deviation value. Diagnostic system.   A photoelectric pyranometer for measuring the amount of solar radiation is provided, and based on the measured amount of solar radiation, provided in the first and second measuring devices, the capacity of the load capacitor used at the time of measuring the current-voltage characteristic is determined The diagnostic system of the solar cell strings in any one of the Claims 1 to 9 characterized by doing.   The solar cell strings diagnostic system according to claim 10, wherein a discharge resistance is always connected in parallel with the load capacitor when measuring the current-voltage characteristics.   The data used for calculation of the said rated output ratio is filtered by setting the acceptance | permission determination level of the minimum output level with respect to the largest output power value of the said measurement reference | standard panel, The data used in calculation of the said rated output ratio is any The diagnostic system of the solar cell strings according to claim 1.   13. The device according to claim 1, wherein the first and second measuring devices extract the maximum output power value and transmit it to the diagnostic device each time of one measurement sweep. Solar cell strings diagnostic system as described. The performance diagnosis of the solar cell strings is performed using a measurement reference panel which has conversion characteristics and temperature characteristics equivalent to the solar cell strings to be diagnosed and which is installed under a solar radiation condition equivalent to the installation surface of the solar cell strings. A diagnostic method to
A first step of measuring a current-voltage characteristic of the solar cell strings and calculating a maximum output power value which is a power value at a maximum output point of the solar cell strings based on the measured current-voltage characteristics;
A second step of measuring current-voltage characteristics of the measurement reference panel and calculating a maximum output power value of the measurement reference panel based on the measured current-voltage characteristics;
Third, calculating a rated output ratio which is a ratio of the maximum output power value of the solar cell strings obtained in the first step to the maximum output power value of the measurement reference panel obtained in the second step Step and
A fourth step of performing performance diagnosis of the solar cell strings based on the rated output ratio calculated in the third step;
A method of diagnosing solar cell strings, comprising:

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