Solar panel inspection device and inspection method

Abstract

Provided is an inspection device and an inspection method for a solar cell panel that is less susceptible to the effects of solar radiation conditions when using a photoluminescence (PL) inspection method. [Solution] Under sunlight irradiation, an open-state PL image is taken with the solar panel open, and a closed-state PL image is taken with the solar panel operating at the maximum power point under the control of a power conditioner, and a differential brightness value ΔPL is calculated from the difference image between the open-state PL image and the closed-state PL image. A pseudo FF value (ΔPL / (Voc×Isc)) is calculated by dividing this differential brightness value ΔPL by the open-circuit voltage value Voc and the short-circuit current specification value Isc, and the power generation performance of the solar panel is evaluated based on this pseudo FF value.

Description

[Technical field]

[0001] The present invention relates to an inspection device and an inspection method for a solar cell panel. [Background technology]

[0002] The presence or absence of defects in solar panels can be determined by inspections at the time of manufacture and shipment. However, solar panels that have already been installed and used as solar power generation systems may have different power generation performance due to deterioration or damage, breaks in internal circuits, short circuits in bypass circuits, etc., depending on the usage conditions. As solar power generation systems become more widespread and expand, there is an increasing need to efficiently determine the power generation performance of solar panels when maintaining, inspecting, or reusing solar panels.

[0003] For example, when reusing a solar cell module, it is necessary to understand the structure and electrical power generation performance of the solar cell module and determine whether it can be reused based on the results, but it requires a lot of effort and cost to remove the installed solar cell module, transport it to a building, etc. For this reason, for example, Patent Document 1 proposes a PL inspection method that uses photoluminescence (hereinafter also referred to as "PL"), which is one of the methods for inspecting the presence or absence of defects in solar cells under the irradiation of sunlight on solar cell modules installed outdoors. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6999911 Summary of the Invention [Problem to be solved by the invention]

[0005] The method of inspecting a solar cell panel disclosed in Patent Document 1 is capable of inspecting the presence or absence of defects in solar cells. However, even if a solar cell module in a string to be inspected has a defect in IV characteristics, for example, a solar cell module with a low open-circuit voltage value Voc as an IV characteristic, it can only be evaluated based on the difference in pixel brightness values ​​between an open-state PL image and a closed-state PL image (difference brightness value ΔPL). In addition, when evaluating a solar cell module in a different solar cell string, the conditions at the time of PL camera shooting, such as the difference in the amount of solar radiation, may differ, and accurate comparison and evaluation cannot be performed based only on the difference brightness value ΔPL.

[0006] The present invention has been made in consideration of these circumstances, and has as its object to provide an inspection device and method for solar cell panels that are less affected by solar radiation conditions when using a photoluminescence (PL) inspection method, which is one method of inspecting solar cells for defects in a solar power generation system. [Means for solving the problem]

[0007] In order to solve the above problem, a first technical means of the present invention is an inspection device for a solar cell panel connected via a switch to a power conditioner that performs maximum power point tracking (MPPT), the inspection device including an imaging means for imaging the solar cell panel, and a PL imaging device for generating an open state PL image captured by the imaging means in a state in which the switch is open and the solar cell panel is open under irradiation of sunlight, and a closed state PL image captured by the imaging means in a state in which the switch is closed and the solar cell panel operates at a maximum power point (MPP) under control of the power conditioner under irradiation of sunlight. the open state PL image and the closed state PL image are generated by a PL image generating means, a PL image for determination generating means for generating a PL image for determination consisting of a difference image between the open state PL image and the closed state PL image, a ΔPL calculation means for calculating a differential brightness value ΔPL of the solar cell panel from the PL image for determination, a voltage measuring means for measuring an open circuit voltage value Voc of the solar cell panel in a state where the switch is open and closed under irradiation by sunlight, and a pseudo FF value calculation means for calculating a pseudo FF value ΔPL / (Voc×Isc) from the short circuit current specification value Isc of the solar cell panel, the open circuit voltage value Voc, and the differential brightness value ΔPL.

[0008] The second technical means of the present invention is characterized in that, in the first technical means, the judgment PL image is generated from a plurality of the open state PL images and a plurality of the closed state PL images that are respectively captured.

[0009] A third technical means of the present invention is characterized in that, in the first or second technical means, it further comprises a power generation performance determination means for determining the power generation performance of the solar cell panel based on the pseudo FF value.

[0010] A fourth technical means of the present invention is the third technical means, characterized in that the power generation performance determination means determines the power generation performance by comparing the current pseudo FF value of the solar panel to be inspected with the past pseudo FF value of the solar panel to be inspected.

[0011] A fifth technical means of the present invention is characterized in that, in the third technical means, the power generation performance determination means determines the power generation performance by comparing the current pseudo FF value of the solar cell panel to be inspected with the current pseudo FF value of another solar cell panel having the same specifications as the solar cell panel to be inspected.

[0012] A sixth technical means of the present invention is an inspection method for a solar panel connected via a switch to a power conditioner that performs maximum power point tracking (MPPT), the method including an open-state PL image capturing step of capturing an open-state PL image of the solar panel in a state in which the switch is open under irradiation of sunlight, an open-state voltage value measuring step of measuring an open-state voltage value Voc of the solar panel in a state in which the switch is open under irradiation of sunlight, and a step of measuring an open-state voltage value Voc of the solar panel in a state in which the switch is closed under irradiation of sunlight and the solar panel is operated at a maximum power point (MPP) under the control of the power conditioner. The method includes a closed state PL image capturing process for capturing a closed state PL image of the solar cell panel, a judgment PL image generating process for generating a judgment PL image consisting of a difference image between the open state PL image and the closed state PL image, a ΔPL calculation process for calculating a differential brightness value ΔPL of the solar cell panel from the judgment PL image, and a pseudo FF value calculation process for calculating ΔPL / (Voc×Isc) as a pseudo FF value from the short circuit current specification value Isc of the solar cell panel, the open circuit voltage value Voc, and the differential brightness value ΔPL, and is characterized in that the power generation performance of the solar cell panel is judged based on the pseudo FF value.

[0013] The seventh technical means of the present invention is characterized in that, in the sixth technical means, the judgment PL image is generated from a plurality of the open state PL images and a plurality of the closed state PL images that are respectively captured.

[0014] The eighth technical means of the present invention is characterized in that, in the sixth or seventh technical means, the power generation performance of the solar cell panel is determined by comparing the current pseudo FF value of the solar cell panel to be inspected with the past pseudo FF value of the solar cell panel to be inspected.

[0015] The ninth technical means of the present invention is characterized in that, in the sixth or seventh technical means, the power generation performance of the solar cell panel is determined by comparing the current pseudo FF value of the solar cell panel being inspected with the current pseudo FF value of another solar cell panel having the same specifications as the solar cell panel being inspected. Effect of the Invention

[0016] According to the first and sixth technical means of the present invention, it is possible to inspect the power generation performance of a solar cell panel while the solar cell panel is installed and in operation, and it is possible to obtain an inspection device and inspection method for a solar cell panel that are less susceptible to the effects of solar radiation conditions.

[0017] According to the second and seventh technical means of the present invention, a determination PL image is generated from multiple open state PL images and multiple closed state PL images, thereby reducing the influence of changes in solar radiation between the time when the open state PL image and the time when the closed state PL image are captured.

[0018] According to the third technical means of the present invention, by setting the judgment conditions in advance, it is possible to automatically judge the power generation performance of the solar cell panel.

[0019] According to the fourth and eighth technical means of the present invention, the deterioration state of the solar panel to be inspected can be accurately known by comparing the pseudo FF value with that at the time of installation, for example. Also, by carrying out periodic inspections, the deterioration state over time can be known.

[0020] According to the fourth and eighth technical means of the present invention, since solar cell modules of the same specifications are usually used in a solar power generation system, it is possible to identify deteriorated solar cell modules even if the pseudo FF values ​​at the time of installation or in the past are not stored. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a diagram for explaining one configuration of a solar power generation system. [Diagram 2] 1 is a diagram showing an example of the configuration of a solar cell panel inspection device according to the present invention; [Diagram 3] FIG. 2 is a diagram for explaining the relationship between the IV characteristics of a solar cell and the pseudo FF value of the present invention. [Figure 4] 1 is a diagram for explaining an inspection flow in a solar cell panel inspection method according to the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, with reference to the drawings, a preferred embodiment of the solar cell panel inspection device and inspection method of the present invention will be described in the case where the inspection unit of the solar cell panel is a solar cell string. In the following description, configurations with the same reference numerals in different drawings are considered to be similar, and their description may be omitted. Note that the present invention is not limited to the examples of these embodiments, and includes all modifications within the scope of the matters described in the claims and within the scope of equivalents. In addition, as long as a combination of multiple embodiments is possible, the present invention includes any combination of the embodiments.

[0023] 1 is a diagram for explaining one configuration of a solar power generation system, which is the subject of the solar cell panel inspection device and inspection method of the present invention. In order to obtain a desired amount of power generation, the solar cell of the solar power generation system usually has a configuration of a solar cell module 11 unit by connecting multiple solar cell cells, and further has a configuration of a solar cell string 12 unit by combining multiple solar cell modules 11 and connecting them in series. Each solar cell module 11 has an internal circuit in which solar cell cells are connected in series, and a bypass circuit in which a bypass diode is connected in parallel to this internal circuit.

[0024] The solar cell strings 12 are further connected to a junction box 20 to aggregate power, thereby constituting a solar cell array 13. The solar cell arrays 13 are further connected to a power collection box 30 to aggregate power, and are connected to a power conditioner (PCS: Power Conditioning Subsystem) 40. In one configuration example shown in FIG. 1, three solar cell strings 12 constitute one solar cell array 13, and the three solar cell arrays 13 are connected to the power collection box 30. In the present invention, the term solar cell panel is used to collectively refer to a solar cell module 11 unit, a solar cell string 12 unit, a solar cell array 13 unit, or a collection of multiple solar cell arrays. The solar cell strings 12 and the solar cell arrays 13 are installed over a wide area, making it difficult to find an abnormal or deteriorated solar cell string 12 or solar cell array 13.

[0025] The junction box 20 is a device for collecting DC power generated by a plurality of solar cell strings 12, with each solar cell string 12 serving as one circuit. The junction box 20 has switches 21 provided for each solar cell string 12, and various circuit elements such as a backflow prevention element and a lightning arrester (not shown). Similarly, the current collection box 30 is a device for collecting DC power generated by a plurality of solar cell arrays 13, with each solar cell array 13 serving as one circuit. Like the junction box 20, the current collection box 30 has switches 31 provided for each solar cell array 13, and various circuit elements such as a backflow prevention element and a lightning arrester (not shown).

[0026] The DC power collected by the current collecting box 30 is output to the AC system by the PCS 40. The PCS 40 is a power converter for converting the DC power generated by the solar cell into AC power, and performs power conversion when the solar cell panel is irradiated with light such as sunlight. The PCS 40 controls the power passing through the PCS 40 by switching (on / off) a semiconductor switch to convert the DC power into AC power, and converts the power into AC power by maximum power point tracking (MPPT) to be described later, so that the DC power output by the solar cell panel is maximized. Note that the PCS 40 may be configured to be connected to a plurality of current collecting boxes 30 and collect power from the plurality of current collecting boxes 30, in which case a switch is provided for the output from each current collecting box 30.

[0027] Fig. 2 is a diagram showing an example of the configuration of a solar cell panel inspection device according to the present invention, and Fig. 2 shows a case where a solar cell string 12 is targeted as an inspection unit of a solar cell panel to be inspected. The inspection device includes a camera 50 as an imaging means for photographing the solar cell string 12, a voltmeter 60, and an inspection device main body 100 that processes the image of the solar cell string 12 photographed by the camera 50 to generate an image required for determining power generation performance and calculate a pseudo FF value.

[0028] The camera 50 photographs the solar cell panel, and is not limited to any camera as long as it has sensitivity to the wavelength of PL light emitted from the solar cell. When a solar cell string is to be inspected, the camera 50 is preferably set at a position where it can photograph the entire solar cell string 12, but the position of the camera 50 may be configured to be movable so that the solar cell modules 11 included in the solar cell string 12 can be photographed one by one or multiple times. In addition, when the inspection target covers a large area such as a solar cell array 13, the camera 50 may be mounted on an unmanned aerial vehicle (drone).

[0029] In addition, it is desirable to provide an optical filter or a hood for the camera 50. For example, in the case of a silicon crystal solar cell, PL light, which is near-infrared light having a peak at 1150 nm, is generated, so it is desirable to use a bandpass filter as the optical filter, which does not transmit visible light but transmits near-infrared light with a wavelength of 1150 nm. In addition, by attaching a hood, noise such as diffuse reflection light entering the camera 50 can be significantly reduced.

[0030] The voltmeter 60 is for measuring the open-circuit voltage value Voc of the solar cell string 12, and the switch 21 is provided in the connection box 20 for each solar cell string 12 and is connected so that the open-circuit voltage value Voc of the solar cell string 12 can be measured when the switch 21 is in an open state. The switch 21 is controlled by a switch control means 108 of the inspection device main body 100, which will be described later.

[0031] The inspection device main body 100 has a function of calculating a pseudo FF value and judging the power generation performance of the solar cell based on the pseudo FF value as necessary. The inspection device main body 100 includes a CPU 110 and a storage unit 120 as hardware. The storage unit 120 is for storing various programs and data for operating the inspection device main body 100, the short circuit current specification value Isc, and pseudo FF values ​​121 calculated in the past and this time. The CPU 110 operates the programs stored in the storage unit 120 as a calculation device, thereby realizing various functions required for the inspection device main body 100. As examples of functional units that perform these functions, FIG. 2 shows a PL image generating means 101, a PL image generating means for judgment 102, a ΔPL calculating means 103, a voltage measuring means 104, a pseudo FF value calculating means 105, a power generation performance judging means 106, a display / alarm means 107, and a switch control means 108.

[0032] Each functional unit will be described below. The PL image generating means 101 controls the camera 50 to capture images of the photovoltaic string 12 in a state where the switch 21 is open and in a state where the switch 21 is closed, obtains captured images from the camera 50, and temporarily stores the captured images in the storage unit 120. In this description, an image captured of the photovoltaic string 12 in a state where the switch 21 is open is referred to as an "open state PL image", and an image captured of the photovoltaic string 12 in a state where the switch 21 is closed is referred to as a "closed state PL image".

[0033] The determination PL image generating means 102 generates a determination PL image consisting of a difference image between the luminance values ​​of each pixel of the open state PL images and the closed state PL images temporarily stored in the storage unit 120. When there are a plurality of open state PL images and a plurality of closed state PL images, an open state average PL image consisting of the average luminance values ​​of each pixel of the plurality of open state PL images and a closed state average PL image consisting of the average luminance values ​​of each pixel of the plurality of closed state PL images are generated, and a determination PL image consisting of a difference image between the luminance values ​​of each pixel of the open state average PL image and the closed state average PL image is generated. When obtaining the average or difference of the luminance values ​​of each pixel, an image recognition process is performed to calculate the average or difference between pixels at the same shooting position in the plurality of shot images.

[0034] The ΔPL calculation means 103 specifies the positions of the solar cells in the solar cell string 12 from the determination PL image generated by the determination PL image generation means 102, and calculates the differential luminance value ΔPL by counting the luminance values ​​of the pixels corresponding to the solar cells. The calculated differential luminance value ΔPL is temporarily stored in the storage unit 120.

[0035] The voltage measuring means 104 is for measuring the open circuit voltage value Voc of the photovoltaic string 12 by the voltmeter 60 when the switch 21 is in an open state, and the measured open circuit voltage value Voc is temporarily stored in the storage unit 120.

[0036] The pseudo FF value calculation means 105 calculates a pseudo FF value, which will be described later, from the differential luminance value ΔPL, the open circuit voltage value Voc, and the short circuit current specification value Isc stored in the storage unit 120, and stores the calculated pseudo FF value of each photovoltaic string 12 in the storage unit 120 as a pseudo FF value 121. The calculated pseudo FF value is also transmitted to the display / warning means 107, which displays it on a display panel or the like. A maintenance inspector can determine which photovoltaic string 12 has deteriorated by looking at the pseudo FF value for each photovoltaic string 12 displayed on a display panel or the like.

[0037] The power generation performance determination means 106 automatically performs performance evaluation of the photovoltaic string 12 to be inspected, and performs the evaluation by either or both of the following two methods. The first method is performed by comparing the current pseudo FF value of the photovoltaic string 12 to be inspected with the past pseudo FF value. It is preferable that the past pseudo FF value is obtained as an initial performance check when the photovoltaic string 12 is installed and stored in the storage unit 120 as an initial pseudo FF value. The second method is performed by comparing the current pseudo FF value of the photovoltaic string 12 to be inspected with the current pseudo FF value of another photovoltaic string 12 having the same specifications as the photovoltaic string 12 to be inspected. In the case of an existing photovoltaic panel, data of the initial pseudo FF value may not be available, and in that case, the second method can be used.

[0038] In both the first and second methods, if the pseudo FF value obtained in the current test is equal to or smaller than a predetermined ratio of the pseudo FF value to be compared, or is equal to or smaller than a predetermined magnitude, the power generation performance determination means 106 determines that the photovoltaic string 12 being tested is degraded. The determination result is transmitted to the display / warning means 107.

[0039] The display / warning means 107 displays the pseudo FF value for each photovoltaic string 12 sent from the pseudo FF value calculation means 105 and the performance judgment result for each photovoltaic string 12 sent from the power generation performance judgment means 106. Furthermore, when the performance judgment result for the photovoltaic string 12 sent from the power generation performance judgment means 106 is evaluated as being deteriorated, the display / warning means 107 issues a warning to a maintenance inspector as necessary.

[0040] The switch control means 108 controls the opening and closing operation of the switch 21 for each solar cell string 12 provided in the connection box 20, or the switch 31 for each solar cell array 13 provided in the current collection box 30. The switch control means 108 cooperates with the PL image generation means 101 to open and close the switch 21 so that the PL image generation means 101 can obtain an open state PL image and a closed state PL image, and cooperates with the voltage measurement means 104 to open and close the switch 21 so that the voltage measurement means 104 can measure the open voltage value Voc of the solar cell string 12.

[0041] Next, the pseudo FF value of the present invention will be described. Fig. 3 is a diagram for explaining the relationship between the IV characteristics of a solar cell and the pseudo FF value of the present invention.

[0042] A solar cell is a junction between an n-type semiconductor, in which electrons are the main carriers, and a p-type semiconductor, in which holes are the main carriers. A depletion layer containing neither electrons nor holes is formed at the junction between the two, and the p-side of this depletion layer is negatively charged, while the n-side is negatively charged, resulting in a diffusion potential difference. When light with an energy greater than the forbidden band width is irradiated onto the depletion layer, an excess of electron-hole pairs is generated, and the generated electron-hole pairs are separated by the diffusion potential difference, causing the n-side to be negatively charged and the p-side to be positively charged, resulting in a voltage appearing at both ends. Then, a current is extracted to the outside through electrodes provided on both the n-type and p-type semiconductors. Meanwhile, when the generated electron-hole pairs recombine, light is generated, and this generated light is photoluminescence (PL).

[0043] In a normal solar cell string 12, when the switch 21 is open, carriers in the solar cell are not extracted to the outside as a current, so the carrier density is high and the PL emission due to the recombination of electron-hole pairs is also strong. When the switch 21 is closed, the carrier density in the solar cell is low due to the current flow, so the PL emission is weak or does not occur. On the other hand, in a solar cell string 12 that has a defect such as a break in the internal circuit or a short circuit such as soldering of a bypass circuit, the PL emission is about the same whether the switch 21 is open or closed.

[0044] In this embodiment, the difference in brightness ΔPL, which is the difference in brightness of PL light emitted from the solar cell string 12 when the switch 21 is open and closed, is used, but since some solar cell modules 11 in the solar cell string 12 have a low open circuit voltage value Voc as an IV characteristic, and the conditions at the time of camera photography, such as differences in the amount of solar radiation, are different, an accurate comparison evaluation with other solar cell strings 12 cannot be performed by evaluation based only on the difference in brightness ΔPL. For this reason, in the present invention, the solar cell string 12 is evaluated by quantifying it using a pseudo FF value that applies a fill factor (FF), which is an index of the IV characteristic, using the open circuit voltage value Voc and the short circuit current specification value Isc.

[0045] 3, point (a) indicates the operating point of the photovoltaic string 12 when the switch 21 is opened, and point (b) indicates the operating point when the photovoltaic string 12 is operated at the maximum power point by maximum power point tracking (MPPT). The voltage value at point (a) where no current is applied is the open voltage value Voc, and the PL luminance value (light emission intensity) PL(a) at point (a) is greater than the PL luminance value (light emission intensity) PL(b) in the current-applied state.

[0046] The FF value, which is an index of the electrical characteristics in the IV characteristic, can be expressed by the following equation using the maximum generated power value P (MPP), the open circuit voltage value Voc, and the short circuit current value Isc'. FF value = P(MPP) / (Voc×Isc')

[0047] On the other hand, since the differential luminance value ΔPL, which is the difference between the PL luminance value PL(a) and the PL luminance value PL(b), is a variable of the same dimension as the maximum power generation value P (MPP), in the present invention, the pseudo FF value is calculated using the following equation. Pseudo FF value = ΔPL / (Voc × Isc) Here, since it is difficult to obtain the short-circuit current value Isc' in practice, the short-circuit current specification value Isc obtained from the specification values ​​of the solar cell module 11 of the target solar cell string 12 is used.

[0048] In a photovoltaic power generation system, normally, the photovoltaic modules 11 with the same specifications are used, so that the FF values ​​of normal photovoltaic strings 12 are the same. Similarly, the pseudo FF values ​​of normal photovoltaic strings 12 are also the same, so that the photovoltaic strings 12 in the entire photovoltaic power generation system can be accurately compared and evaluated. Therefore, by comparing the pseudo FF value obtained by the inspection with the pseudo FF value at the time of installation of the photovoltaic string 12 to be inspected, or with the pseudo FF values ​​of other photovoltaic strings with the same specifications at the time of inspection, it is possible to evaluate and determine the superiority or inferiority of the power generation performance.

[0049] Next, a method for inspecting a solar panel will be described. Fig. 4 is a diagram for explaining an inspection flow in the method for inspecting a solar panel according to the present invention, and the procedure of the method for inspecting a solar panel will be described with reference to the configuration example in Fig. 2.

[0050] The inspection of the solar cell panel is performed in a state where the solar cell string 12 is irradiated with sunlight L. First, in step S1, the switch control means 108 opens the switch 21 connected to the solar cell string 12 to be inspected, and connects it to the voltmeter 60 so that the terminal voltage of the solar cell string 12 can be measured.

[0051] Next, moving to step S2, the PL image generating means 101 operates the camera 50 to capture an image of the entire solar cell string 12, and records the captured image in the storage unit 120 (step S3). The camera 50 is set up in advance so that it can capture an image of the entire solar cell string 12, but if the camera 50 cannot capture an image of the entire solar cell string 12 in one shot, the solar cell modules 11 may be captured in multiple images or one at a time. The processes from step S2 to step S3 constitute an open-state PL image capturing process for generating an open-state PL image.

[0052] Next, the process proceeds to step S4, where the processes from step S2 to step S3 are repeated N times (for example, 50 times). This is because, in order to obtain a PL image for determination as a difference image for which luminance can be counted in subsequent processes, it is necessary to obtain a clearer PL image from multiple captured images. Next, the process proceeds to step S5, where the voltage measurement means 104 obtains the open circuit voltage value Voc measured by the voltmeter 60 and stores it in the memory unit 120. The process in step S5 constitutes the open circuit voltage value measurement step.

[0053] Next, the process proceeds to step S6, where the switch 21 connected to the photovoltaic string 12 to be inspected is closed by the switch control means 108. As a result, the photovoltaic string 12 is operated under maximum power point tracking control by the PCS 40, and is operated at point (b) in the IV characteristic shown in FIG.

[0054] Next, the process proceeds to step S7, where the PL image generating means 101 operates the camera 50 to capture an image of the entire solar cell string 12, and records the captured image in the storage unit 120 (step S8). If the camera 50 cannot capture an image of the entire solar cell string 12 in one shot, the solar cell modules 11 may be captured in multiple images or one at a time, as in step S2. Next, the process proceeds to step S9, where the process from step S7 to step S8 is repeated N times (e.g., 50 times). This is for the same reason as in the case of obtaining an open state PL image. The process from step S7 to step S8 constitutes a closed state PL image capturing process for generating a closed state PL image.

[0055] Next, the process proceeds to step S10, where the determination PL image generating means 102 generates a determination PL image consisting of a difference image between the open state PL image and the closed state PL image temporarily stored in the storage unit 120. When there are a plurality of open state PL images and a plurality of closed state PL images, the determination PL image, which is a difference image, is generated based on an average image obtained by averaging the luminance value of each pixel as described above. The process in step S10 corresponds to a determination PL image generating step. Next, the process proceeds to step S11, where the ΔPL calculation means 103 identifies the position of the solar cell in the solar cell string 12 from the determination PL image generated by the determination PL image generating means 102, counts the luminance value of the pixel corresponding to the solar cell, calculates the differential luminance value ΔPL, and stores the calculated differential luminance value ΔPL in the storage unit 120. The process in step S11 corresponds to a ΔPL calculation step.

[0056] Next, proceeding to step S12, the pseudo FF value calculation means 105 reads out the short circuit current specification value Isc stored in the storage unit 120, and also reads out the open circuit voltage value Voc and the differential luminance value ΔPL stored in the storage unit 120, and calculates the pseudo FF value (=ΔPL / (Voc×Isc)) in step S13. The calculated pseudo FF value is transmitted to the display / warning means 107 in step S14 and is displayed on a display panel or the like. Here, when calculating the pseudo FF value of the solar cell strings 12 constituted by solar cell modules 11 of the same specification, the short circuit current specification value Isc will be the same value in the calculation formula, and therefore, for example, the value can be treated as 1. The process in step S13 is a pseudo FF value calculation step.

[0057] The series of processes can end at step S14, but if the power generation performance of the solar panel is to be automatically determined, the process proceeds from step S14 to step S15, where the power generation performance determination means 106 evaluates the performance of the solar cell string 12 that is the subject of this inspection. The power generation performance can be evaluated by either or both of the two methods described above, and a method selected in advance can be used. The result of the determination made by the power generation performance determination means 106 is sent to the display / warning means 107 in step S16 and is displayed on a display panel or the like.

[0058] In this embodiment, performance evaluation is performed on a solar cell string 12 basis operated by a switch 21. If it is desired to identify a solar cell module 11 in the solar cell string 12 whose performance has deteriorated, a differential brightness value ΔPL is calculated on a solar cell module 11 basis using a judgment PL image, which is a differential image between an open state PL image and a closed state PL image, and the obtained differential brightness value ΔPL is compared with the differential brightness value ΔPL of other solar cell modules of the same specifications to determine the performance deterioration of the solar cell module 11.

[0059] In the above, in this embodiment, the inspection is performed in units of the solar cell string 12 as the inspection target, but the present invention can evaluate the power generation performance in units of switch operation (solar cell string units or solar cell array units). When the inspection is performed in units of the solar cell array 13 as the inspection target, the switch control means 108 controls the opening and closing of each switch 31 of the current collection box 30, while the PL image generation means processes the captured image for each solar cell array 13, and the voltage measurement means 104 measures the open voltage value Voc for each solar cell array 13. Then, the pseudo FF value calculation means 105 calculates the pseudo FF value for each solar cell array 13. [Explanation of symbols]

[0060] 11...Solar cell module 12...Solar cell string 13…Solar cell array 20…Connection box 21...Switch 30…Current collector box 31...Switch 50…Camera 60…Voltmeter 100...Inspection device main body 101...PL image generation means 102...Judgment PL image generation means 103...ΔPL calculation means 104...Voltage measuring means 105...Pseudo FF value calculation means 106...Power generation performance determination means 107...Alarm means 108...switch control means 110…CPU 120...Storage section 121…Pseudo FF value

Claims

1. An inspection device for a solar panel connected via a switch to a power conditioner that performs maximum power point tracking (MPPT), An imaging means for imaging the solar panel; a PL image generating means for generating an open-state PL image captured by the imaging means in a state in which the switch is open and the solar cell panel is open under irradiation of sunlight, and a closed-state PL image captured by the imaging means in a state in which the switch is closed and the solar cell panel is operated at a maximum power point (MPP) under control of the power conditioner under irradiation of sunlight; a determination PL image generating means for generating a determination PL image formed of a difference image between the open state PL image and the closed state PL image; a ΔPL calculation means for calculating a differential luminance value ΔPL of the solar cell panel from the determination PL image; a voltage measuring means for measuring an open circuit voltage value Voc of the solar cell panel in an open state when the switch is opened under irradiation of sunlight; a pseudo FF value calculation means for calculating a pseudo FF value ΔPL / (Voc×Isc) from the short circuit current specification value Isc of the solar cell panel, the open circuit voltage value Voc, and the differential luminance value ΔPL; A solar cell panel inspection device comprising:

2. 2. The solar cell panel inspection device according to claim 1, wherein the determination PL image is generated from a plurality of the open state PL images and a plurality of the closed state PL images that are respectively captured.

3. 3. The solar cell panel inspection device according to claim 1, further comprising a power generation performance determination means for determining a power generation performance of the solar cell panel based on the pseudo FF value.

4. 4. The solar cell panel inspection device according to claim 3, wherein the power generation performance determination means determines the power generation performance by comparing the current pseudo FF value of the solar cell panel to be inspected with the past pseudo FF value of the solar cell panel to be inspected.

5. 4. The solar cell panel inspection device according to claim 3, wherein the power generation performance determination means determines the power generation performance by comparing the current pseudo FF value of the solar cell panel to be inspected with the current pseudo FF value of another solar cell panel having the same specifications as the solar cell panel to be inspected.

6. A method for inspecting a solar panel connected via a switch to a power conditioner that performs maximum power point tracking (MPPT), comprising: an open-state PL image capturing step of capturing an open-state PL image of the solar cell panel in an open state with the switch being opened under irradiation of sunlight; an open circuit voltage value measuring step of measuring an open circuit voltage value Voc of the solar cell panel in an open state in which the switch is opened under irradiation of sunlight; A closed-state PL image capturing process for capturing a closed-state PL image of the solar cell panel under irradiation of sunlight with the switch closed and the power conditioner operating at a maximum power point (MPP) by control; a determination PL image generating step of generating a determination PL image consisting of a difference image between the open state PL image and the closed state PL image; a ΔPL calculation step of calculating a differential luminance value ΔPL of the solar cell panel from the determination PL image; a pseudo FF value calculation step of calculating ΔPL / (Voc×Isc) as a pseudo FF value from the short circuit current specification value Isc of the solar cell panel, the open circuit voltage value Voc, and the differential luminance value ΔPL, A method for inspecting a solar cell panel, comprising determining a power generation performance of the solar cell panel based on the pseudo FF value.

7. 7. The method for inspecting a solar panel according to claim 6, wherein the determination PL image is generated from a plurality of the open state PL images and a plurality of the closed state PL images that are respectively captured.

8. 8. The method for inspecting a solar cell panel according to claim 6 or 7, characterized in that the power generation performance of the solar cell panel is determined by comparing the current pseudo FF value of the solar cell panel to be inspected with the past pseudo FF value of the solar cell panel to be inspected.

9. 8. The method for inspecting a solar cell panel according to claim 6 or 7, characterized in that the power generation performance of the solar cell panel is determined by comparing the current pseudo FF value of the solar cell panel to be inspected with the current pseudo FF value of another solar cell panel having the same specifications as the solar cell panel to be inspected.

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