JP2017221010A - Power generation output acquisition method for solar cell module, and power generation output acquisition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power generation output acquisition method capable of acquiring power generation output of multiple solar cells modules efficiently in a short time.SOLUTION: A measurement system comprises: a measurement device 20 for measuring a power generation output property of a solar cell module; a power supply device 24 which applies a current/voltage for generating electroluminescence to the solar cell module; an imaging apparatus 22 for imaging the solar cell module being emitted by generating the electroluminescence; and a calculation device 26 for processing the picked-up image to calculate power generation output. Based on a ratio between a value relating to a light emission strength of a reference solar cell module 10A and a value relating to a light emission strength of the remaining solar cell modules, the calculation device calculates a power generation output value of the remaining solar cell modules or a value corresponding thereto.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power generation output acquisition method and a power generation output acquisition device that acquire power generation outputs of a plurality of solar cell modules connected in series and / or in parallel that constitute a solar power generation system, and in particular, a voltage and The present invention relates to a method and an apparatus for acquiring a power generation output of a solar cell module of a solar power generation system that is installed and in operation using electroluminescence (EL) generated by applying a current.

  Photovoltaic power generation system that receives light such as sunlight and generates power is a power generation method that uses solar energy, which is renewable energy, and in recent years, installation on the roof of ordinary houses and the roof of buildings has become widespread, Furthermore, the introduction of large-scale solar power generation systems such as so-called mega solar installed on a vast site is progressing, and many solar power generation systems are installed in a wide variety of places.

  A solar power generation system uses a solar cell module in which a plurality of solar cells are combined as a basic unit, and a plurality of solar cell modules are connected in series and / or in parallel according to the power generation output and the size of the installation location. A solar power generation system in which solar cell modules are arranged is constructed.

  The installed photovoltaic power generation system is subjected to maintenance inspection work when an abnormal state such as a decrease in power generation output occurs or periodically. Factors that decrease the power generation output include various factors such as the surface of the solar cell module being soiled and not receiving enough light such as sunlight, if a malfunction or failure occurs inside the solar cell module, aging, etc. However, at the time of maintenance inspection, an operator visits the installation location of the photovoltaic power generation system in order to specify the presence or absence of a defect or the cause and one of the many solar cell modules constituting the photovoltaic power generation system. The inspection and confirmation work of the sheet is performed, and the work for confirming the presence or absence of the abnormality is performed.

  As one of the detection methods for defects of the solar cell module, a bias voltage is applied to the solar cell module in the forward direction to generate electroluminescence (EL), and the sun is obtained from an image (EL image) obtained by photographing the light emission state. A method for identifying a defect in a battery module is known (Patent Documents 1 and 2).

International Publication No. 2006/059615 JP 2014-228517 A

  However, in large-scale photovoltaic power generation systems such as so-called mega solar modules and residential photovoltaic power generation systems in which a large number of solar cell modules are connected, the inspection and maintenance workers have to install all the solar cell modules one by one at the installation location. Performing inspection / confirmation work is very inefficient because it takes a lot of time and effort.

  In addition, the methods disclosed in Patent Documents 1 and 2 only evaluate by comparing the light emission intensity of EL images, and the relationship with the actual power generation output of the solar cell module cannot be grasped. I can't get a realistic figure.

  Furthermore, an actual large-scale photovoltaic power generation system is installed on a vast site exposed to wind and rain, and the surrounding environment varies depending on the location. However, it is difficult to accurately evaluate the power generation output by simply comparing only the emission intensity of EL images.

  Accordingly, an object of the present invention is to provide a solar cell module power generation output acquisition method and a power generation output acquisition device capable of efficiently acquiring the power generation outputs of a plurality of solar cell modules constituting an existing solar power generation system in a short time. Is to provide.

  In order to achieve the above object, a method for acquiring power generation output of a solar cell module according to the present invention is a power generation output acquisition method for estimating power generation output of a plurality of solar cell modules connected in series and / or in parallel. A measurement step of measuring the power generation output characteristic of one of the reference solar cell modules, and a current value and a voltage value set based on the power generation output characteristic measured in the measurement step, An imaging step of applying electroluminescence to the battery module to image a plurality of solar cell modules that emit light by electroluminescence, and a light emission intensity of each of the plurality of solar cell modules based on the image captured by the imaging step For the emission intensity of the one reference solar cell module. And calculating a power generation output value of each of the remaining solar cell modules or a value corresponding thereto based on a ratio of a value to the light emission intensity of each of the remaining solar cell modules among the plurality of solar cell modules And a process.

  In order to achieve the above object, a power generation output acquisition device for a solar cell module of the present invention is a power generation output acquisition device for acquiring power generation outputs of a plurality of solar cell modules connected in series and / or in parallel. Measuring means for measuring the power generation output characteristic of one of the reference solar cell modules, and a current value and a voltage value set based on the power generation output characteristic measured by the measurement means, Imaging means for applying electroluminescence to the battery module to photograph a plurality of solar cell modules that emit light by electroluminescence, and the emission intensity of each of the plurality of solar cell modules based on the images photographed by the photographing means For the emission intensity of the one reference solar cell module. And the power generation output value of each of the remaining solar cell modules or a value corresponding thereto is calculated based on the ratio of the value to the light emission intensity of each of the remaining solar cell modules among the plurality of previous positive battery modules. And an arithmetic means.

  According to the power generation output acquisition method and power generation output acquisition device of the solar cell module of the present invention, the solar power generation system is based on the electroluminescence photographed image data by measuring the power generation output characteristics of one reference solar cell module. It is possible to obtain the power generation output values of a large number of solar cell modules constituting the power generation, and to evaluate the power generation outputs of a large number of solar cell modules easily and in a short time. Enable implementation.

It is a figure which shows the structural example of a solar energy power generation system. It is a figure which shows the apparatus structural example for acquiring the electric power generation output of the solar energy power generation system in this invention. The example of the power generation output characteristic of the measured solar cell module is shown. It is a figure which shows the voltage value VEL and current value IEL selected from the measured electric power generation output characteristic (IV characteristic). It is an image example which image | photographed the solar cell module of the light emission state which electroluminescence (EL) generate | occur | produced. It is a flowchart of a calculation process. It is a figure for demonstrating the numerical value calculated | required by a calculating process. 6 is an example of image data obtained by binarizing the example of FIG. 5 with a threshold value. It is an image example which image | photographed three solar cell modules of the light emission state which EL generate | occur | produced. FIG. 10 is image data obtained by binarizing images corresponding to each of FIG. It is a table | surface which shows the calculated value containing the estimated electric power generation output value calculated | required from the binarized image data of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention.

  FIG. 1 is a diagram illustrating a configuration example of a photovoltaic power generation system. A photovoltaic power generation system is an existing photovoltaic power generation system that has already been installed, such as a large-scale photovoltaic power generation system called a so-called mega solar system and a residential photovoltaic power generation system. It has a configuration in which a plurality of combined solar cell modules 10 are connected. A solar cell string 12 in which a plurality of solar cell modules 10 are connected in series is formed, and further, a plurality of solar cell strings 12 are arranged in series or in parallel through a connection box 16 to constitute a solar cell array 14. The junction box 16 is a device that collects DC power generated by each solar cell string 12 using one solar cell string 12 as one line, and includes a switch 18, and further includes a backflow prevention element, a lightning arrester, and an output terminal. And various circuit elements. In the case of a large-scale photovoltaic power generation system in which a plurality of connection boxes 16 are arranged, a current collection box (not shown) that collects outputs from the plurality of connection boxes 16 may be further provided.

  The DC power collected in the connection box 16 is supplied to a power converter (power conditioner) (not shown), and the power converter converts the DC power into AC power and links it to the power system.

  FIG. 2 is a diagram illustrating an apparatus configuration example for acquiring the power generation output of the photovoltaic power generation system according to the present invention. As a device configuration, a current for generating electroluminescence in the measuring device 20 that measures the power generation output characteristics of at least one reference solar cell module 10A, or in the solar cell module 10 (or in a solar cell string unit or a solar cell array unit). A power supply device 24 for applying voltage, a photographing device 22 for photographing the solar cell module 10 in a light emitting state by generation of electroluminescence (or a solar cell string unit or a solar cell array unit), and processing the captured image to generate power An arithmetic unit 26 that calculates the output is included. The computing device 26 is a general-purpose computer device that acquires and records the measurement data of the measuring device 20 and the image data of the imaging device 22, and further processes the image data by an image processing program, thereby calculating the power generation output. Execute. The following steps are performed using the apparatus configuration.

  (1) A measurement process in which the measurement device 20 measures the output characteristics of at least one reference solar cell module among a plurality of solar cell modules constituting the solar power generation system.

  (2) A photographing process in which a predetermined current / voltage is applied to all the target solar cell modules by the power supply device 24 to generate electroluminescence, and the light emitting state is photographed by the photographing device 22.

  (3) One reference solar in which a value related to the emission intensity of each of the plurality of solar cell modules is detected based on the photographed image, and the power generation output is measured in the measurement step among the plurality of solar cell modules. A calculation step of calculating the power generation output of each of the remaining solar cell modules or a value corresponding thereto by the calculation device based on the comparison between the value related to the light emission intensity of the battery module and the value related to the light emission intensity of each of the remaining solar cell modules. .

  Hereinafter, each step will be described.

<Measurement process>
The reference solar cell module 10A for measuring the power generation output characteristics may be any one of the plurality of solar cell modules, and a solar cell module that is easy to work with can be selected. In many cases, the plurality of solar cell modules constituting the solar power generation system are of the same type (the same manufacturer and the same model number), and any one solar cell module can be selected. It is not necessary to confirm the quality of the power generation output of the selected solar cell module. When the solar cell module is composed of a plurality of types, the power generation output characteristics are measured for each type. The solar cell module has a connector structure at the end of the cable extending from the terminal so that the solar cell string can be configured by connecting to an adjacent solar cell module. The connector of the selected solar cell module is pulled out and separated from the adjacent solar cell module, and the measuring device 20 for measuring the power generation output is connected to the connector, and the measurement is executed.

  The measurement of the power generation output characteristic is performed in a power generation state in which light such as sunlight is received, and can be measured in a short time by connecting the measuring device 20. In the present invention, the power generation output characteristics need only be measured by one solar cell module 10A selected as the reference solar cell module, and in the operation state where power is actually generated, the power generation of the remaining many solar cell modules is performed. Without interrupting power generation, the opportunity loss of power generation can be minimized.

  FIG. 3 shows an example of the measured power generation output characteristics of the reference solar cell module. The power generation output characteristic of the solar cell module is obtained as a correlation value representing the relationship between current (I) and voltage (V) output by power generation, and is also referred to as an IV characteristic. The measurement data of the power generation output characteristic is stored in the arithmetic device (computer device) 26.

<Photographing process>
After the measurement of the power generation output characteristics, in a state where there is no light such as sunlight and power generation is not performed, that is, at night, the solar cell module 10 to be inspected and maintained (a reference solar cell module 10A whose output characteristics have been measured in advance) Electroluminescence (hereinafter referred to as EL) is generated and the light emission state is photographed. EL is generated by applying a predetermined voltage and current to the solar cell module 10 using the power supply device 24, and the surface of the solar cell module 10 is imaged by the imaging device 22. The photographing device 22 is an ultraviolet photographing device that photographs ultraviolet rays generated by EL, for example, and the photographed image is stored in the arithmetic device 26 as digital data. The photographing may be performed not only for each solar cell module but also for each solar cell string or each solar cell array. A plurality of solar cell modules 10 that are subject to inspection and maintenance including the reference solar cell module 10A may be taken. Take a picture. In that case, a voltage and a current having a magnitude obtained by multiplying the voltage value VEL and the current value IEL for generating EL in one solar cell module by the number of solar cell modules included in the photographing range to be photographed at one time. It is applied by the power supply device 24.

  FIG. 4 is a diagram illustrating a voltage value VEL and a current value IEL selected from the measured power generation output characteristics (IV characteristics). In the applied voltage and current, the voltage value VEL and current value IEL for one solar cell module are the voltage value VEL and current value IEL appropriately selected from the power generation output characteristic curve measured in the measurement process, and the efficiency In order to generate the EL automatically, it is preferable to use the voltage value VEL and the current value IEL near the operating point at which the output of the solar cell module is maximum. The power value PEL is a power value obtained from the voltage value VEL and the current value IEL.

  FIG. 5 is an example of an image taken of a light emitting solar cell module in which EL is generated. As illustrated in FIG. 5, the EL may be photographed for each solar cell module subject to inspection and maintenance. For example, a plurality of solar cells such as a solar cell array unit that looks down on the whole. You may image | photograph a battery module as one image. By photographing a plurality of solar cell modules, the number of times of photographing is reduced and the photographing time is shortened.

  In addition, when EL is photographed, the insulation resistance values between the plus (+) electrode line and the ground and between the minus (−) electrode line and the ground of the solar cell module to be photographed are measured. This is for confirming whether or not leakage current is generated from the plus (+) electrode wire and the minus (−) electrode wire to the ground. When the leakage current is large, contact with the solar cell module may cause an electric shock in the human body or a fire in the combustible material, which is an indispensable work for confirming its soundness.

<Calculation process>
FIG. 6 is a flowchart of the calculation process. FIG. 6A is a calculation process for the image data of the reference solar cell module among the solar cell modules subject to inspection and maintenance. FIG. The calculation process with respect to the image data of remaining solar cell modules other than a reference | standard solar cell module is shown. The calculation process is executed by the calculation device 26. FIG. 7 is a diagram for explaining the numerical values obtained by the calculation process. FIG. 7A shows a plurality of n solar cell modules M1 to Mn (Mm: M2 to Mn−) to be subjected to maintenance and inspection. FIG. 7B is a table showing numerical values corresponding to the arrangement example of 1). In FIG. 7, the solar cell module M1 is a reference solar cell module.

  In FIG. 6A, among the captured image data, among the pixels in the captured image region of the reference solar cell module M1, the number of pixels equal to or greater than a predetermined threshold value for the light emission intensity (for example, luminance) is counted. The number C1 is acquired (S100). In FIG. 6B as well, pixels in the captured image area of solar image modules M2 to Mn that are subject to maintenance and inspection other than the reference solar cell module (referred to as target solar cell modules) among the captured image data. Among them, the number of pixels equal to or greater than a predetermined threshold for the emission intensity (for example, luminance) is counted, and the count numbers C2 to Cn are obtained (S200). The threshold value is for determining a reference of the emission intensity, and may be an arbitrary value. For pixel counting, a threshold value is automatically determined by using a function of existing image processing software (the threshold value may be manually set), and the number of pixels having a luminance equal to or higher than the threshold value is counted. Since there is a difference in the number of pixels constituting the image area per solar cell module depending on the shooting angle and distance, it is preferable to use a normalized value in order to correct the difference. For example, the ratio value of the count number with respect to the total number of pixels in the captured image area of each solar cell module is calculated as the normalized count numbers NC1 to NCn for the solar cell modules to be inspected and maintained (S102, S202). The value related to the emission intensity is not limited to the count number, and other index values such as a pixel area equal to or greater than a threshold value may be used.

  Then, as the power generation output (referred to as a reference power generation output value) P1 of the reference solar cell module M1, the power generation output obtained from the current value and the voltage value applied in the photographing process are associated, and the power generation output value of the reference solar cell module M1 It is stored as P1 (S104).

  For the target solar cell modules M2 to Mn, reference ratios R2 to Rn (= NC2 / NC1 to NCn / NC1) between the respective normalized count numbers NC2 to NCn and the normalized count number NC1 of the reference solar cell module M1 are calculated. Further, based on the reference ratios R2 to Rn, estimated values (referred to as estimated power generation output values) P2 to Pn of the power generation outputs of the target solar cell modules M2 to Mn are obtained (S206). Specifically, the target solar cell modules P2 to Pn are estimated by multiplying the reference ratios R2 to Rn obtained for the normalized count numbers NC2 to NCn of the target solar cell modules by the reference power generation output value P1. The power generation output values P2 to Pn can be obtained.

  The inventor conducted an experiment to compare a reference power generation output value obtained by actual measurement and an estimated power generation output value obtained by the above-described calculation with respect to a plurality of existing solar cell modules, as shown in Examples described later. Were confirmed to match with high accuracy. Since the estimated power generation output value is calculated as a ratio with the reference power generation output value, even if the power generation output value of the reference solar power generation module is relatively lower than the power generation output value of the remaining solar power generation modules, high accuracy is obtained. Estimation is possible.

  Further, information on the rated power generation output value RP is obtained from the rated specification information of the solar cell module, and a rating ratio Z1 (P1 / RP) of the reference power generation output value P1 of the reference solar cell module M1 with respect to the rated power generation output value RP is obtained ( S106) For the target solar cell modules M2 to Mn, the rated ratios Z2 to Zn (P2 / RP to Pn / RP) of the power generation outputs P2 to Pn of the target solar cell modules M2 to Mn with respect to the rated power generation output value RP are obtained ( S208). By comparison with the rated power generation output value RP, it is possible to grasp the secular change of the power generation output value of each solar cell module. Further, by periodically carrying out the present invention, it is possible to accumulate aging data and evaluate changes in the power generation output of the solar cell module. For example, when the reduction amount of the power generation output of some solar cell modules is larger than the power generation output of many other solar cell modules, the solar cell module can be determined as defective. In comparison between the rated power generation output value RP and the power generation output value P, a difference value may be used as a comparison value instead of or in addition to the rating ratio Z.

<Example>
The inventor conducted an experiment to compare the reference power generation output value obtained by actual measurement and the estimated power generation output value obtained by the above-described calculation for the existing solar cell module (same manufacturer, same model number).

  About the said measurement process, the output characteristic of three existing solar cell modules in the applicant's site where an inventor works was measured with the measuring apparatus. FIG. 8 is a diagram showing measurement results of the output characteristics. “Reference” shown in FIG. 8 is an output characteristic of the reference solar cell module selected from the three solar cell modules, and the output characteristics of the remaining two solar cell modules are “target 1”, “target”. 2 ”. The output characteristics of “target 1” and “target 2” are measured for comparison with estimated power generation output values obtained by a calculation process described later. In FIG. 8, the current values of “reference”, “target 1”, and “target 2” at an applied voltage of 20 V are 8.60 A, 8.33 A, and 6.81 A, respectively, and thus the measured power generation outputs are 172.0 W and 166.6 W, respectively. 136.2W.

  About the said imaging | photography process, the predetermined electric current and voltage were applied to three solar cell modules including a reference | standard solar cell module, thereby generating electroluminescence, and image | photographed the light emission state. FIG. 9 is an image example in which three solar cell modules in a light emitting state in which EL is generated are photographed. FIG. 9A is a reference solar cell module, and FIG. 9B and FIG. This is an image of the solar cell modules “Target 1” and “Target 2”. FIG. 9A is the same as the image of FIG.

  In the calculation step, estimated power generation output values of the remaining solar cell modules “target 1” and “target 2” were calculated based on the captured images. FIGS. 10A, 10B, and 10C are image data obtained by binarizing images corresponding to FIGS. 9A, 9B, and 9C with threshold values. FIG. 11 is a table showing calculation values including estimated power generation output values obtained from the binarized image data. Here, based on this calculation, the power generation output values of the target 1 and the target 2 are 172 × 0.971 = 167 for the target 1 and 172 × 0.797 = 137 for the target 2.

  The estimated power generation output values of the solar cell modules of “Target 1” and “Target 2” at an applied voltage of 20 V are 167 W and 137 W, respectively, and the power generation output values actually measured in the measurement process are 166.6 W and 136.2 W, respectively. Since they are almost the same, we were able to confirm that the estimation was possible with high accuracy. Moreover, in the image which image | photographed EL, when there exists an area | region where emitted light intensity is relatively low among the image areas of a solar cell module, a local malfunction can also be determined. For example, by generating data obtained by binarizing the distribution of light emission intensity using the threshold value for counting the above-described count number, a defective portion can be clearly identified. For example, as shown in FIG. 10C, it is possible to determine the presence or absence of a local defective area (a portion surrounded by a dotted line) having a relatively low light emission intensity.

  In the present invention, by measuring the output characteristics of one solar cell module during daylight hours when solar radiation is being generated, and photographing the solar cell module in which EL is generated at night when power generation is not performed. In addition to minimizing power generation opportunity loss, it is possible to estimate the power generation output of solar cell modules subject to maintenance and inspection with high accuracy, and to efficiently evaluate the power generation output of many solar cell modules in a short time. It becomes like this.

  In the above description, the arithmetic processing such as the count number and the power generation output value has been described in units of solar cell modules. However, the present invention is not limited to units of solar cell modules. For example, solar cells configured by connecting a plurality of solar cell modules in series. The calculation may be performed in units of strings and in units of solar cell arrays configured by connecting a plurality of solar cell strings in parallel. In that case, what is necessary is just to multiply a connected power generation output value by the specification of one solar cell module.

  The present invention is not limited to the above-described embodiment, and there are design changes within a range that does not depart from the gist including various modifications and corrections that can be conceived by those having ordinary knowledge in the field of the present invention. Of course, it is included in the present invention.

  10: solar cell module, 10A: reference solar cell module, 12: solar cell string, 14: solar cell array, 16: junction box, 20: measuring device, 22: photographing device, 24: power supply device, 26: arithmetic device

Claims (6)

In a power generation output acquisition method for acquiring power generation outputs of a plurality of solar cell modules connected in series and / or in parallel,
A measurement step of measuring the power generation output characteristic of one reference solar cell module among the plurality of solar cell modules;
A plurality of solar cells emitting light by electroluminescence by applying current and voltage of current values and voltage values set based on the power generation output characteristics measured in the measurement step to a plurality of solar cell modules to generate electroluminescence. A shooting process for shooting the module;
Based on the image photographed in the photographing step, a value related to the light emission intensity of each of the plurality of solar cell modules is obtained, and a value related to the light emission intensity of the one reference solar cell module and the remaining of the plurality of solar cell modules A power generation output acquisition method comprising: a calculation step of calculating a power generation output value of each of the remaining solar cell modules or a value corresponding to the power generation output value of each of the remaining solar cell modules based on a ratio to a value relating to the emission intensity of each solar cell module.   2. The power generation output acquisition according to claim 1, wherein the value related to the light emission intensity is the number of pixels having a light emission intensity equal to or higher than a predetermined threshold among the pixels constituting each image region of the plurality of solar cell modules. Method.   The current value of the current and voltage applied in the photographing step and the value of the power generation output of the one reference solar cell module obtained from the voltage value are multiplied by the ratio, and each of the remaining solar cell modules is The power generation output acquisition method according to claim 1 or 2, wherein a power generation output value is calculated.   The calculation step includes calculating a comparison value between the rated power generation output value of the solar cell module and each of the power generation output values of the plurality of solar cell modules calculated in the calculation step. The power generation output acquisition method according to any one of the above.   4. The method according to claim 1, wherein the measuring step is performed during the day when the solar cell module is generating power, and the photographing step is performed at night when the solar cell module is not generating power. The power generation output acquisition method according to one. In the power generation output acquisition device for acquiring the power generation output of a plurality of solar cell modules connected in series and / or in parallel,
Measuring means for measuring the power generation output characteristics of one reference solar cell module among the plurality of solar cell modules;
A plurality of solar cells emitting light by electroluminescence by applying current and voltage of current value and voltage value set based on the power generation output characteristics measured by the measuring means to a plurality of solar cell modules to generate electroluminescence. Photographing means for photographing the module;
Based on the image photographed by the photographing means, a value related to the emission intensity of each of the plurality of solar cell modules is obtained, and a value related to the emission intensity of the one reference solar cell module and the remaining of the plurality of solar cell modules A power generation output acquisition device comprising: a calculation means for calculating a power generation output value of each of the remaining solar cell modules or a value corresponding to the power generation output value of each of the remaining solar cell modules based on a ratio to a value relating to the emission intensity of each solar cell module.